Pro-survival Pathways Research Articles

SCAMP1 silencing inhibits proliferation by attenuating multiple pro-survival signaling pathways in gastric cancer.

Secretory carrier-associated membrane protein 1 (SCAMP1) is the most universally expressed member of the SCAMP family, and its ability to facilitate endocytosis was demonstrated approximately two decades ago. Nevertheless, its roles in cancer biology are largely unknown, although its expression is significantly increased in most cancer types. Herein, we examined the expression of SCAMP1 in gastric cancer (GC) tissues and found that it was aberrantly increased and positively correlated with tumor size and lymph node metastasis. More importantly, increased SCAMP1 expression was associated with poor prognosis in patients with GC. Functional experiments demonstrated that SCAMP1 knockdown markedly suppressed the proliferation of GC cells in vitro and in vivo. RNA sequencing assays demonstrated that SCAMP1 knockdown altered the expression profile of GC cells, and a significant portion of the altered genes were enriched in receptor tyrosine kinases and their related downstream signaling pathways. Immunoblotting confirmed that the Akt/MAPK/Stat signaling pathway was strongly attenuated in GC cells with SCAMP1 depletion. Taken together, these results demonstrated that SCAMP1 drives hyperproliferation in GC cells, thus suggesting that further investigation into the mechanisms and translational value of SCAMP1 in treating patients with GC is warranted.

Chemotherapy Resistance in Cancer: Mechanism and Roadmap to Evade Exploring Apoptosis

Chemotherapy resistance indicates the non-responsiveness of cancer cells to the cytotoxic and inhibitory effects of chemo drugs attributed to either intrinsic or extrinsic resistance mechanisms in cancer cells. Studies so far indicate that drug resistance can be triggered by a multitude of factors such as the over-expression of drug efflux pumps, DNA repair mechanisms, modifications in the drug target such as point mutations and gene amplification, over-expression of anti-apoptotic proteins and down-regulation of pro-apoptotic signals, presence of cancer stem cells and immune-suppressive cells, excessive cytokine production, tumor heterogeneity, epigenetic changes, activation of alternate pro-survival signaling pathways, etc. Both host and tumor-related factors can contribute to therapy resistance. Currently, chemo resistance poses the foremost setback in the successful treatment of cancer, and it exerts significant stress on the available medical resources. Besides the costs associated with the treatment, patients go through severe emotional and physical trauma. Chemotherapy resistance is also a major contributor to accelerated metastasis and invasion. Dose-escalation is not always practical since the associated side effects may increase apart from increasing the treatment costs. Several studies are ongoing to address this issue productively, such as therapeutic molecules designed to restore the apoptotic machinery. Site-specific delivery of pro-apoptotic agents such as small molecules, antibodies, peptides, etc. targeting the apoptosis pathway is also thoroughly studied. Moreover, the efficacy of combination strategies is also a topic of research.

Pharmacological Targeting of Senescence with Senolytics as a New Therapeutic Strategy for Neurodegeneration.

Cellular senescence is a state of permanent cell-cycle arrest. Early in life, senescence has a physiologic role in tumor suppression and wound healing. However, gradually, as these senescent cells accumulate over the lifespan of an organism, they contribute to inflammation and the progression of age-related diseases, including neurodegeneration. Targeting senescent cells using a class of drugs known as "senolytics" holds great promise for the management of Alzheimer's and Parkinson's disease. Already, several senolytic compounds have been shown to ameliorate cognitive deficits across several preclinical models of neurodegeneration. Most of these senolytics (e.g., dasatinib) are repurposed clinical or experimental anticancer drugs, which trigger apoptosis of senescent cells by interfering with pro-survival pathways. However, outside of their senolytic function, many first-generation senolytics also have other less appreciated neuroprotective effects, such as potent antioxidant and anti-inflammatory activity. In addition, some senolytic drugs may also have negative dose-limiting toxicities, including thrombocytopenia. In this review, we discuss the various biologic pathways targeted by the leading senolytic drugs, namely dasatinib, quercetin, fisetin, and navitoclax. We further evaluate the clinical transability of these compounds for neurodegeneration, assessing their adverse effects, pharmacokinetic properties, and chemical structure. SIGNIFICANCE STATEMENT: Currently, there are no effective disease-modifying treatments for the most prevalent neurodegenerative disorders, including Alzheimer's and Parkinson's disease. Some of the drugs currently available for treating these diseases are associated with unwanted side-effects and/or become less efficacious with time. Therefore, researchers have begun to explore new innovative treatments for these belligerent diseases, including senolytic drugs. These agents lead to the apoptosis of senescent cells thereby preventing their deleterious role in neurodegeneration.

Comparison of the blood immune repertoire with clinical features in chronic lymphocytic leukemia patients treated with chemoimmunotherapy or ibrutinib.

Chronic lymphocytic leukemia (CLL) is characterized by the accumulation of CD19+ CD5+ clonal B lymphocytes in the blood, bone marrow, and peripheral lymphoid organs. Treatment options for patients range from historical chemoimmunotherapy (CIT) to small molecule inhibitors targeting pro-survival pathways in leukemic B cells, such as the Bruton's tyrosine kinase inhibitor ibrutinib (IBR). Using biobanked blood samples obtained pre-therapy and at standard response evaluation timepoints, we performed an in-depth evaluation of the blood innate and adaptive immune compartments between pentostatin-based CIT and IBR and looked for correlations with clinical sequelae. CD4+ conventional T cells and CD8+ cytotoxic T cells responded similarly to CIT and IBR, although exhaustion status differed. Both treatments dramatically increased the prevalence and functional status of monocyte, dendritic cell, and natural killer cell subsets. As expected, both regimens reduced clonal B cell levels however, we observed no substantial recovery of normal B cells. Although improvements in most immune subsets were observed with CIT and IBR at response evaluation, both patient groups remained susceptible to infections and secondary malignancies during the study.

Deciphering the Immune Microenvironment in Waldenstrom's Macroglobulinemia

Recent studies have demonstrated the occurrence of somatic mutations of MYD88 and CXCR4 as key players in Waldenstrom's Macroglobulinemia (WM) pathogenesis and disease progression. Despite the significant improvement in the knowledge of the molecular mechanisms supporting WM biology whether immunosuppressive mechanisms could contribute to WM pathogenesis remains unexplored. We interrogated the transcriptome signatures of the bone marrow (BM) microenvironment of WM patients (n:22) as compared to healthy individuals (n:10), we found a significant enrichment for a Treg-signature, and for CD40/CD40L signaling-related genes (FDR <0.001; P <0.01). These findings were confirmed using a transgenic murine lymphoplasmacytic/WM model, where the BM immune microenvironment showed an increased number of infiltrating CD4+ T lymphocytes over CD8+ T cells. Further characterization of the T-cell compartment revealed the presence of abundant CD4+CD25+FoxP3+ Treg cells, with respect to control mice. Murine WM cells recruited a significantly higher number of more abundant Ki67+Treg cells, as compared to B lymphocytes from healthy mice. Collectively, these results suggest that immunosuppressive Treg cells may play in supporting WM disease biology. These findings prompted us to focus on Tregs and their role in supporting WM pathogenesis. We performed bulk RNA sequencing of Tregs isolated from both WM patients (n:14) and healthy donors/HD (n:8); showing a peculiar transcriptome signature characterizing WM-derived Tregs as compared to their normal cellular counterpart. WM patient-derived Tregs presented with transcriptome profiling enriched for FOXP3-target genes and to Treg induction, as compared to healthy donor-derived Tregs; with WM-Tregs showing a significant enrichment for genes related to interferon- and TNFα-related genes via NF-kB. The functional impact of Treg in WM biology was next studied. We observed a significantly higher ability of WM cells to favor both induction and expansion of CD4+CD25+FoxP3+ Tregs, as compared to HD-derived CD19+ B-cells; paralleled by a significantly higher increase of Ki67-positive Treg induced by WM cells as compared to HD-derived CD19+ B-cells. Same results were obtained using WM primary cells. Data were further corroborated by demonstrating significant enrichment of several pro-proliferative- and pro-survival pathways in WM-Tregs, versus HD-counterpart, including MAPK- and PI3K/AKT-related genes. To gain insight into the potential molecular mechanisms responsible for the observed Treg induction in WM, we performed scRNAseq using the whole cell population harvested at the end of the induction assay. We evaluated the B-T-cell interactions at single cell level, adopting a B->T cross-talk model; and identified a set of four high-priority genes (CD40, TNF, TNFSF14, ICAM2): although all of them were expressed in B cells, only the expression of CD40 was maximal and virtually restricted to the B clusters, with the other three genes showing a more diffuse pattern. Importantly, CD40-ligand was shown to be the interactor expressed within the Treg cell compartment. Given the identified CD40/CD40L axis as a potential regulator of the WM cell/Treg cross-talk, we used the CD40/CD40L inhibitor DRI-C21045; and found a significant decrease in Treg induction and Treg proliferation. Halting CD40/CD40L interaction inhibited Treg induction and growth, also within the context of CXCR4-mutated WM, supported by inhibition of p-AKT and p-ERK in Treg cells. CD40/CD40L blockade led to inhibition of WM cell growth. Overall our studies have demonstrated the existence of a Treg-mediated immunosuppressive phenotype in WM, which can be therapeutically reversed by blocking the CD40L/CD40 axis to inhibit WM cell growth.

Interplay between Inflammatory Microenvironment and RUNX1-Mediated Transcriptomic Changes Drives Defective Hematopoiesis in Familial Platelet Disorder

Background: Familial platelet disorder (FPD) is caused by germline loss-of-function mutations in RUNX1 an essential transcription factor regulating hematopoiesis. The absence of functional RUNX1 leads to mild-to-moderate thrombocytopenia, platelet dysfunction, and increased bleeding in FPD patients. In ~40% of cases, the patients progress to overt leukemia at median age of 33 years through unknown mechanisms. FPD patients also present with skin allergy and eczema which are associated with systematic elevation of cytokines. Given the well-established connection between inflammation and leukemia initiation and progression, we sought to investigate whether inflammatory stress play a role in regulating abnormal hematopoiesis and eventually cause clonal evolution in FPD. Methods: We acquired bone marrow cells from FPD patients who had not developed leukemia yet. We then compared FPD bone marrow hematopoietic stem and progenitors (HSPCs) with healthy progenitors using in vitro differentiation and colony formation assays. For comprehensive mechanistic evaluation, we performed 10x single-cell RNA sequencing (scRNA-seq) on FPD (n=10) and healthy (n=4) bone marrow cells, analyzing >100,000 cells using Seruat package. We evaluated cytokine levels in bone marrow fluid and peripheral blood using 65-plex Luminex assay. The impact of the inflammatory cytokines and intervention strategies were tested using in vitro differentiation and colony formation assays. The results were validated in vivo using mice with germline Runx1 mutation. Results: We identified that FPD progenitors are impaired in megakaryocytic (>2.0-fold, p<0.05) and erythroid differentiation with increased myeloid differentiation (>1.7-fold, p<0.05) compared to healthy control. In addition, FPD HSPCs show increased myeloid colony formation (>1.6-fold, p<0.05) and serial replating ability. scRNA-seq identified 18 cell clusters and pseudotime analysis revealed higher percentage of FPD cells differentiating towards monocytes, supporting enhanced myeloid differentiation. The pathway enrichment analysis of differentially expressed genes in HSC cluster revealed upregulation of inflammatory (TNFα via NF-kB) and pro-survival pathways (PI3K/AKT/mTOR). Accordingly, cytokine profiling revealed upregulation of numerous cytokines and chemokines in FPD compared to healthy samples including TNFα, CXCL8, CCL24, CCL2, and IL1β (>2.5 to 1000-fold, p<0.05), secreted by progenitors, monocytes, and MSCs. Further, under inflammatory stress mediated by TNFα, CXCL8, CCL24, CCL2, and IL1β, FPD HSPCs exhibited resistant to growth suppression and have increased myeloid colony formation. However, pharmacological inhibition of individual cytokines only partially rescued the differentiation defects, possibly due to compensatory effects of each cytokine. Phospho-flow analysis revealed that increased cytokine levels leads to the activation of PI3K/mTOR and JAK signaling that we also found upregulated using scRNA-seq analysis. Interestingly, inhibition of mTORi (rapamycin and AZD2014), PI3Ki (idelalisib), and JAKi (ruxolitinib) showed an increase in percentage of megakaryocytes (up to 2-fold, p<0.05) and a decrease in monocytes (up to 0.6-fold change, p<0.05). Also, inhibition of these pathways in FPD reduced cytokines levels. In line with human FPD data, in vivo treatment of Runx1 R188Q/+ mouse with ruxolitinib suppressed myeloid differentiation with no effects on megakaryocytes, while rapamycin resulted in significantly increased platelet activation compared to untreated mice (>1.7-fold, p<0.05) and a reduction of monocytes (<0.5-fold, p<0.05), suggesting mTOR inhibition might be an effective intervention strategy. Conclusion: FPD HSPCs manifest defective megakaryopoiesis with increased myelopoiesis. The elevated autocrine and paracrine inflammatory stress is an early event in FPD, driving myeloid differentiation. This inflammatory stress mediates activation of PI3K/mTOR and JAK signaling, leading to augmented myeloid differentiation. Consequently, the observed FPD phenotypes are the result of combined transcriptional changes and inflammatory stress. Targeting inflammatory and pro-survival signaling at an early stage might mitigate hematopoietic defects and delay disease evolution in FPD. Our results advance mechanistic understanding and hold significant clinical implications.

Enhancement of Mitochondrial Membrane Potential and Pro-Survival Pathways with Azole Compound C7 Resulting in Expansion of Hematopoietic Stem and Progenitor Cells

Ex-vivo expansion of hematopoietic stem & progenitor cells (HSPC) could improve hematopoietic recovery and reduce post-transplant complications, especially for umbilical cord blood (UCB) grafts where limited total cell numbers result in delayed engraftment. Freshly-thawed UCB mononucleated cells (MNCs) or purified CD34 + cells were cultured in animal component free medium supplemented with C7 and a basal cytokine cocktail. The effects of the expansion protocol were measured with phenotypic, in-vitro, and in-vivo functional assays. A range of molecular techniques were also performed to elucidate the mechanisms of action of C7. In previous studies, expansion cultures initiated with UCB-MNCs and supplemented with C7 resulted in significant expansions of UCB HSPC over 11 days and these grafts demonstrated elevated and sustained multi-lineage engraftment of human cells in primary NSG mice (Bari et al., 2018). In UCB-CD34+ enriched cultures, the addition of C7 to a basal cytokine cocktail also boosted absolute CD45+CD34(BR)+CD38-CD45RA- progenitor expansion by 283±29.4 fold over 11 days which was 1.86±0.12 fold higher than control cultures (p<0.001; n=6). Furthermore, C7 induced significant expansion of primitive HSPC in UCB-MNC defined by phenotype CD45+CD34(BR)+CD38-CD45RA-CD90+CD49f+ by more than 633±8.5 fold, which is 7.5±0.16 fold higher compared to control cultures (p<0.01; n=3). The addition of C7 to CD34+ cells from mobilized peripheral blood (PB) and bone marrow (BM) also resulted in a significant expansion of HSPCs (p<0.05; n=3) (Fig 1A). When expanded UCB-CD34+ were engrafted in NSG mice, NSG PB analysis at week 3 and week 28 post-transplantation showed significantly higher (p<0.01) human CD45+ cell engraftment in C7 expanded graft (16.4%±2.6) than cytokine expanded graft (7.8%±0.9). NSG BM analysis at week 31 also exhibited similar trends for human CD45+ cell engraftment in C7 expanded grafts with multilineage reconstitution (p<0.01; n=6). Significantly enhanced CD45+ cell viability (p<0.01; n=3) was observed in C7 cultures compared to control cultures. Mitochondrial health was also improved as confirmed by lower mitochondrial superoxides and higher mitochondrial membrane potential in C7-cultured UCB-MNCs (p<0.05; n=3) that is reflective of reduced reactive oxygen species (ROS) (Fig 1B). As C7 is a chemical analogue of a p38 inhibitor (SB203580), p-p38 (T180/Y182) was significantly reduced in C7-expanded CD34+ culture compared to controls. Significant increases in HIF-1α in C7 expanded CD34+ cells were also observed, potentially indicative of a hypoxic state induced by C7 to benefit HSPC together with reduced levels of ROS. Kinase inhibition profiling studies on C7 identified CK1δ, a kinase involved in Wnt and p53 signalling pathways, as one of the activation targets directly activated by C7. CK1δ was boosted in C7-expanded cells and this was further validated with western blots on C7 expanded pooled CD34+. CK1δ plays a putative role in p53 activation which is stipulated to promote HSC quiescence favouring long-term maintenance of HSPCs. Western blot analysis also revealed that p53 and BCL-2 were increased with C7 expanded CD34+. GSK3β was also boosted in C7 expanded pooled CD34+ cultures possibly as a result of CK1δ signalling leading to increased proliferation via the Wnt signalling pathway. Multiple safety studies were conducted on C7 to ensure its safety in clinical applications. This included the BIOMAP phenotypic safety and toxicology tests on human primary cells, AMES test and fluctuation assays for bacteria and SAFETYscan47 TM In Vitro Pharmacological Profiling for biochemical safety, all of which were negative for any cytotoxicity or off-targets associated with acute toxicity. No changes were detected in cytogenetics and fluorescence in situ hybridization with UCB-MNC for major leukemia-related genetics as well when they were cultured with C7. As a small molecule capable of significant HSPC expansion from both UCB and PB sources, C7 is promising for the future of HSPC transplantation. The mechanism behind C7 is likely to be a multi-pronged one with p38 inhibition, increase in HIF-1α, CK1δ activation, improved mitochondrial health, and induction of pro-survival pathways for expanding HSPC populations.

Oligomannose-Type Glycans in the Antigen Binding Site Identify Origin and Prognosis of Diffuse Large B Cell Lymphoma

The acquisition of N-glycosylation sites (AGS) in the complementarity-determining region (CDR) of the tumor immunoglobulin (Ig) is an early clonal requirement of classic follicular lymphoma (FL). In FL, the AGS are occupied by oligomannose-type glycans, which mediate lymphoma Ig interaction with the microenvironmental lectin dendritic cell-specific intercellular adhesion molecule-3-grabbing nonintegrin (DC-SIGN). This interaction induces a persistent low-level signal, favouring adhesion and ultimately survival and growth of the lymphoma cells in their protected environment . Oligomannose-type glycans can also occupy the CDR-located AGS of a subset of germinal-centre B cell-like (GCB) diffuse large B-cell lymphomas (DLBCL) but the consequences of AGS in DLBCL are less known. We determined the frequency, distribution, and composition of the glycan structures occupying the AGS in DLBCL using a discovery-validation approach with two large independent international public cohorts (BCC, dataset ID: EGAD00001003783; NCI accession phs001444.v1.p1), following our RNAseq Ig assembly pipeline (Ig-Seq-R) and high-resolution mass-spectrometry. Glycan types were compared to our FL cohort (12 samples) and correlated with DLBCL cell of origin (COO), genetic, clinical characteristics and outcome. The full IGHV-IGHD-IGHJ-IGHC transcript sequences were obtained from 251 DLBCL of the BCC, and 339 of the NCI cohort. Sample distribution by COO, clinical or molecular features, LymphGen subtype, progression-free survival (PFS) and overall survival (OS) were not different from the extended public cohorts. AGS were observed in 48-55% GCB-DLBCL, with 84-85% of them located in the CDR. Overall, frequency of CDR-located AGS contrasted dramatically between GCB-DLBCL (41-46%) and activated B-cell like (ABC)-DLBCL (7-10%). Also, within GCB-DLBCL, CDR-located AGS associated mostly with the EZB subtype (68-73%). However, only 66-61% EZB were AGS+ve, all of which were CDR+ve, while the remaining 34-39% had no AGS (AGS-ve EZB). The glycan structures of the synthetic F(ab)s from 35 AGS+ve DLBCL and 12 FL were analyzed by site-specific mass spectrometry. The DLBCL comprised 12 AGS+ve EZB and 23 AGS+ve non-EZB (14 CDR+ve, 9 located in the framework region). Glycan analysis revealed that all AGS+ve EZB and FL were invariably occupied by oligomannose-type glycans (Ig-Mann+ve DLBCL). In contrast, the other AGS+ve DLBCL were not occupied by oligomannose type glycans. They were either occupied by complex glycans (the remaining non-EZB GCB-DLBCL) or not occupied (preferentially the ABC-DLBCL), irrespective of AGS location. These data indicated that CDR+ve EZB Ig were universally and exclusively Ig-Mann+ve DLBCL, share the COO of FL, and have likely been influenced by an environmental driver distinct from the other GCB-DLBCL and ABC-DLBCL. We compared the clinical behavior of Ig-Mann+ve DLBCL versus other DLBCL subtypes including AGS-ve EZB and the other non-EZB GCB-DLBCL and ABC-DLBCL. In both the BCC and NCI cohorts, Ig-Mann+ve DLBCL status identified the subset with the worst PFS and OS of all GCB-DLBCL, not different from ABC-DLBCL (Figure 1A). This contrasted with the other GCB-DLBCL (AGS-ve/EZB and AGS+ve/non-EZB), which all shared an extremely good PFS and OS (Figure 1A). Univariate and multivariate analyses revealed that Ig-Mann+ve status was an independent prognostic factor for PFS and OS (Figure 1B). Gene expression profile analysis revealed that Ig-Mann+ve status associated with an enrichment of MYC, PI3K-Akt-mTORC1, pro-survival, and cell cycle pathways, while proinflammatory and apoptotic pathways were decreased in the Ig-Mann+ve DLBCL compared to AGS-ve/EZB and AGS+ve/non-EZB, independently of MYC translocations and double-hit signature. These data indicate identical COO of a EZB subset with FL cells, and point to a highly selective chronic environmental pressure on Ig-Mann+ve DLBCL negatively affecting patients survival. The combination of Ig gene analysis with the lymphGen classification can predict Ig glycan structure and provide a new fundamental approach to identifying the most aggressive GCB-DLBCL subtype, and the precise environmental tumour interaction (DC-SIGN:Ig-Mann) to intercept therapeutically early in the natural history of Ig-Mann+ve DLBCL.

Addiction to Small Gtpase ARF6-Mediated Sphingolipid Homeostasis By AML but Not the Host

Background Cancer cells' unique metabolic demand has emerged as a promising therapeutic target in Acute Myeloid Leukemia (AML). The vesicular trafficking and signaling gatekeeper, ADP-Ribosylation Factor 6 (ARF6), belongs to the RAS superfamily of small GTPases and has been shown to regulate the homeostasis of lipids such as PIP2, phosphatidic acids, and cholesterol. Here we describe AML cells' unusual addiction to ARF6-mediated sphingolipid homeostasis and its clinical significance. Experiments and Results ARF6 knockdown (KD) or CRISPR-mediated ARF6 knockout (KO) inhibited the proliferation of AML cell lines, THP-1 and MV4-11, as well as the colony formation of primary AML CD34 + cells. Surprisingly, Tamoxifen-induced whole body KO of Arf6 in adult Arf6 f/f;Rosa-CreERT 2 mice led to healthy and grossly normal mice with a normal lifespan. Adult mice lacking ARF6 show no abnormality in complete blood count, urine test, or histology. Hence, ARF6 is genetically indispensable for AML, but not for the host. To confirm AML's addition to ARF6 in vivo, we introduced Arf6 KO in an MLL-AF9-induced AML model in C57BL6/J mice. We are currently following up with the disease progression between Arf6-KO AML group and control AML group, and expect to obtain results before the 2023 ASH meeting. After discovering that ARF6 is genetically necessary for AML but not needed for the host, we analyzed its clinical significance. Since ARF6 mutations are not detected in AML samples, we focused on analyzing its expression. With univariate analysis, we show that high ARF6 expression (top 50%) is significantly associated with worse overall survival (OS) and worse disease-free survival (DFS) of AML patients in the TCGA-NEJM-2013 (TCGA) cohort (N=200) and the Münchner Leukämielabor (MLL) cohort (N=579). In multi-variate analysis, high ARF6 expression is significantly associated with worse OS in the BeatAML cohort (N=562) and shows a trend towards worse OS and DFS in the TCGA cohort. Following a hypothesis-driven approach, we investigated the role of ARF6 in regulating sphingolipid homeostasis by HPLC-MS lipidomic analyses of AML cells (THP-1) with or without ARF6 depletion. Lipidomic profiles revealed that ARF6 KD led to an increase of the overall ceramide/sphingomyelin ratio, suggesting a defect in sphingolipid homeostasis. We then analyzed the expression of sphingolipid metabolic enzymes and observed that ARF6 KD downregulated sphingomyelin synthase 1 and 2 (SGMS1 and SGMS2) expression, hindering ceramide-to-sphingomyelin conversion. Supporting this, we found a positive linear correlation between ARF6 and SGMS1/2 expression among the patients in TCGA cohort, confirming their correlation. High expression of the ARF6 effectors SGMS1/2 is also associated with worse OS and DFS in the TCGA cohort and the MLL cohort in univariate analysis, resembling that of ARF6. Downstream of ceramide accumulation, ARF6 KD inhibited the pro-survival AKT pathway, confirming the pro-apoptotic roles of ceramide in cancers. The anti-proliferative effect of ARF6 depletion can be rescued by sphingomyelinase inhibitor GW4869 (blocking ceramide production) or by expressing a constitutively active form of AKT (AKT1 E17K). To pharmacologically target ARF6, we developed two generations of ARF6 small molecular inhibitor pro-drugs, named NAV-2729 and A6-4471. NAV-2729 and A6-4471 showed high specificity to ARF6 without inhibiting other small GTPases, with in vitro IC 50 in the lower μM range. Both NAV-2729 and A6-4471 inhibited AML cell line proliferation and reduced primary AML cell colony formation in lower μM range. Cord blood normal CD34 + cells are not sensitive to ARF6 inhibitors, but non-specific toxicity was observed at higher concentrations. When tested in vivo with THP-1 xenografts in NSG mice, both inhibitors reduced circulating AML cells without obvious toxicity to the host. Conclusion ARF6 is necessary for AML proliferation and its higher expression is associated with worse patient survival. However, ARF6 is dispensable for normal host physiology. Mechanistically, ARF6 maintains critical ceramide/sphingomyelin balance in AML by regulating SGMS1/2 expression. Pharmacologically inhibiting ARF6 suppressed AML proliferation in vitro and in vivo in a genotype-agnostic fashion. Our study implicates ARF6 as a potentially actionable and safe target in AML.

Quantitative MYD88 L265P Analysis Represents a Powerful Tool for Assessing Disease Response and Evaluating Clinical Trial Performance in Waldenstrom's Macroglobulinemia

Serum IgM measurements represent the current standard for assessing changes in disease burden in Waldenström's Macroglobulinemia (WM). Many agents used to treat WM can significantly affect serum IgM levels without impacting the underlying burden of clonal lymphoplasmacytic cells thereby producing discordant findings. Such agents can raise (CD20-directed monoclonal antibodies, IMiDs), or lower (BTK-, proteasome-, MTOR- inhibitors) serum IgM levels, and impact categorical response assessment. Somatic mutations in MYD88 are found in 95-97% of WM patients, and support tumor growth through activation of multiple pro-survival pathways that include HCK/BTK, SYK and ERK. Nearly all MYD88 mutations in WM are of the L265P variant. Previous studies by us and others have shown that serial quantitative measurements of both bone marrow (BM) and peripheral blood (PB) MYD88 L265P (c.978 T>C) by allele-specific PCR can be used to assess changes in underlying BM disease burden (Blood 121:2051-2058; Leukemia 28:1698-1704). However, the utility of using quantitative allele-specific MYD88 L265P (qMYD88 L265P) analysis has not been studied in prospective clinical trials. As such, we performed a comprehensive study of qMYD88 L265P response assessment utilizing BM and PB CD19-selected tissue across 5 prospective clinical studies in WM: Ixazomib, Dexamethasone and Rituximab (IDR; NCT02400437) Ibrutinib monotherapy (IBR; NCT02604511); Venetoclax monotherapy (VEN; NCT02677324); Ibrutinib plus Ulocuplomab (IBR/ULO; NCT03225716); and Ibrutinib plus Venetoclax (IBR/VEN; NCT04273139). Changes in MYD88 L265P ΔCt were assessed as reported above with ΔCt = Mutant Ct - Wild-type Ct, and higher ΔCt values indicating a lower mutant allele burden, with each ΔCt unit reduction representing a 50% decrease in mutant MYD88 L265P burden. Changes in MYD88 L265P ΔCt were compared to changes in underlying BM disease burden and categorical response assessment using the current (IWWM-11) response criteria (Semin Hematol. 60:97-106). Across all five trials, BM (r=0.52; p<0.001) and PB (r=0.43; p<0.001) MYD88 L265P ΔCt changes from baseline were highly correlated at best response with corresponding changes in underlying BM disease burden determined by repeat BM biopsies. As shown in Fig. 1, comparing changes from baseline in BM MYD88 L265P ΔCt assessments across studies showed marked differences, with greatest reductions observed in patients treated with IBR/VEN, IDR, and VEN alone, than for those treated with IBR alone or IBR/ULO. Similar findings were also observed for corresponding PB MYD88 L265P ΔCt assessments from baseline, with changes in PB MYD88 L265P ΔCt strongly correlating with those of BM MYD88 L265P ΔCt findings across all 5 clinical trials (r=0.67; p<0.001), thereby signifying the ability to use PB MYD88 L265P ΔCt assessments to evaluate treatment responses. We next compared findings from BM and PB MYD88 L265P ΔCt to changes from baseline in serum IgM levels across all 5 trials. At best response, major categorical responses denoted by >50% reduction in serum IgM using IWWM-11 criteria showed commensurate decreases in BM and PB MYD88 L265P ΔCt from baseline in patients receiving IBR/VEN, IDR and VEN alone ( Fig. 2). In contrast, minimal changes in BM and PB MYD88 L265P ΔCt from baseline were observed at best response for most major responders on IBR or IBR/ULO, including individuals who achieved very good partial responses denoted by >90% decrease in IgM by IWWM-11 criteria. In this first prospective evaluation of BM and PB qMYD88 L265P response assessment, we show that both BM and PB L265P qMYD88 analysis can provide more accurate assessment of treatment related changes in disease burden over the current standard of IgM response assessment alone, and can be used to more robustly evaluate clinical trial performance byidentifying treatments or regimens that produce more meaningful tumor reductions in WM patients.

Prosurvival Pathway Protects From Clostridioides difficile Toxin-Mediated Cell Death.

There is an urgent need for new nonantibiotic-based treatment strategies for Clostridioides difficile infection. C. difficile toxin B (TcdB) is a virulent factor that is essential for causing disease. Here, we investigated whether a survival-signaling pathway could protect against TcdB. We found significant increase in caspase-3 apoptotic activity in intestinal epithelial cells of mice exposed to TcdB. Subsequently, activation of the MIF-CD74-Akt prosurvival signaling pathway blocked TcdB-induced caspase-3 activity and intestinal epithelial cell death. This brief report provides proof-of-concept that targeting prosurvival pathways may represent a unique antibiotic-independent strategy for protecting against C. difficile toxin-mediated cell death.

Unveiling the potential effects of acetylsalicylic acid: insights into regeneration in endometrial stem cells

BackgroundAlthough acetylsalicylic acid has been widely used for decades to treat and prevent various diseases, its potential effects on endometrial receptivity and subsequent pregnancy rates are still controversial due to conflicting data: many reports have shown positive effects of acetylsalicylic acid, whereas others have found that it has no effect. Furthermore, the direct effects of acetylsalicylic acid on various functions of normal endometrial cells, especially endometrial stem cells, and their underlying molecular mechanisms have not yet been proven. Recently, studies have revealed that a reduced number of active stem/progenitor cells within endometrial tissue limits cyclic endometrial regeneration and subsequently decreases pregnancy success rates, suggesting that endometrial stem cells play a critical role in endometrial regeneration and subsequent endometrial receptivity.MethodsWe assessed whether aspirin treatment can inhibit various endometrial stem cell functions related to regenerative capacity, such as self-renewal, migration, pluripotency/stemness, and differentiation capacity, in vitro. Next, we evaluated whether SERPINB2 regulates the effects of aspirin on endometrial stem cell functions by depleting SERPINB2 expression with specific shRNA targeting SERPINB2. To further investigate whether aspirin also inhibits various endometrial stem cell functions in vivo, aspirin was administered daily to mice through intraperitoneal (i.p.) injection for 7 days.ResultsIn addition to its previously identified roles, to the best of our knowledge, we found for the first time that acetylsalicylic acid directly inhibits various human endometrial stem cell functions related to regenerative capacity (i.e., self-renewal, migration, differentiation, and capacity) through its novel target gene SERPINB2 in vitro. Acetylsalicylic acid exerts its function by suppressing well-known prosurvival pathways, such as Akt and/or ERK1/2 signaling, through a SERPINB2 signaling cascade. Moreover, we also found that acetylsalicylic acid markedly inhibits regenerative capacity-related functions in endometrial stem cells within tissue.ConclusionsWe have found that acetylsalicylic acid has diverse effects on various endometrial stem cell functions related to regenerative capacity. Our findings are a critical step toward the development of more effective therapeutic strategies to increase the chances of successful pregnancy.B6n3mChCCDtcpomxEHNgX-Video

The Significance of Cathepsin B in Mediating Radiation Resistance in Colon Carcinoma Cell Line (Caco-2).

Cathepsins (Caths) are lysosomal proteases that participate in various physiological and pathological processes. Accumulating evidence suggests that caths play a multifaceted role in cancer progression and radiotherapy resistance responses. Their proteolytic activity influences the tumor's response to radiation by affecting oxygenation, nutrient availability, and immune cell infiltration within the tumor microenvironment. Cathepsin-mediated DNA repair mechanisms can promote radioresistance in cancer cells, limiting the efficacy of radiotherapy. Additionally, caths have been associated with the activation of prosurvival signaling pathways, such as PI3K/Akt and NF-κB, which can confer resistance to radiation-induced cell death. However, the effectiveness of radiotherapy can be limited by intrinsic or acquired resistance mechanisms in cancer cells. In this study, the regulation and expression of cathepsin B (cath B) in the colon carcinoma cell line (caco-2) before and after exposure to radiation were investigated. Cells were exposed to escalating ionizing radiation doses (2 Gy, 4 Gy, 6 Gy, 8 Gy, and 10 Gy). Analysis of protein expression, in vitro labeling using activity-based probes DCG04, and cath B pull-down revealed a radiation-induced up-regulation of cathepsin B in a dose-independent manner. Proteolytic inhibition of cathepsin B by cathepsin B specific inhibitor CA074 has increased the cytotoxic effect and cell death due to ionizing irradiation treatment in caco-2 cells. Similar results were also obtained after cathepsin B knockout by CRISPR CAS9. Furthermore, upon exposure to radiation treatment, the inhibition of cath B led to a significant upregulation in the expression of the proapoptotic protein BAX, while it induced a significant reduction in the expression of the antiapoptotic protein BCL-2. These results showed that cathepsin B could contribute to ionizing radiation resistance, and the abolishment of cathepsin B, either by inhibition of its proteolytic activity or expression, has increased the caco-2 cells susceptibility to ionizing irradiation.

Cytokine Release Syndrome Results in Reduced AML Killing By CD123 CAR T Cells

Background: Chimeric antigen receptor (CAR) T cells have repeatedly demonstrated capacity to induce high rates of response and durable remissions for B cell cancers. In contrast, CAR T cells for the treatment of acute myeloid leukemia (AML) have not yet achieved this impact. We previously demonstrated that CD123 is expressed on AML blasts at high frequency, thus making it an attractive target antigen for AML-directed CAR T cells. Methods and Results: We conducted a pilot study of CD123-directed CAR T cells (CART-123) in adults with relapsed or refractory AML. The primary objective was safety with a secondary objective of anti-leukemia efficacy. Twenty-two subjects were screened, and 20 were eligible for the trial. Fludarabine and cyclophosphamide were used for lymphodepletion (LD). Twelve subjects were infused with CART-123. There were two treatment-related deaths due to cytokine release syndrome (CRS) and infection. Four subjects (33%) achieved complete response with incomplete count recovery (CRi), three subjects had progressive disease, and five had stable disease. Of the four who achieved CRi, one subject remains alive in remission after a relapse and subsequent consolidative hematopoietic stem cell transplant (HSCT). One other subject is alive after HSCT following CART-123 failure. There was evidence of CAR T cell expansion and ten subjects (83%) experienced clinical CRS ranging from Grade I to Grade V. There was no neurotoxicity. To address the apparent paradox of high rates of CART-123 bioactivity (clinical CRS and in vivo expansion) co-occurring with low rates of response, we hypothesized that cytokines produced during CRS may undermine the anti-AML effect of CART cells. We obtained serum drawn from trial subjects at baseline (prior to LD chemotherapy) or during CRS. Serum drawn during CRS promotes primary AML survival in cell culture, while matched baseline serum from the same subjects does not. Individual cytokines secreted during CRS that signal through receptors expressed on myeloid progenitors (such as GM-CSF and Flt3 ligand) reproduced this survival advantage in primary AML blasts when tested at physiologically relevant levels. In contrast, these cytokines did not produce a pro-survival effect in primary patient B-ALL blasts. Crucially, candidate myeloid-acting cytokines, as well as serum drawn during the peak of clinical CRS, promoted resistance of AML to killing by CART-123 in vitro. Using scRNAseq of bone marrow aspirates from subjects on this clinical trial, we found that GM-CSF and FLT3L were most frequently expressed by CD4+ T cells. Exposure of primary AML samples to CRS cytokines led to upregulation of signaling (e.g. JAK/STAT5) and pro-survival pathways. In previous work in B-ALL, we showed that relative resistance to killing can translate to a functional deficit in CART-19 due to development of exhaustion in the CART cells. We similarly find that that exposure to GM-CSF reduces AML blast sensitivity to CART-123, and that the persistence of antigen leads to exhaustion in CART cells (Figure 1). Specifically, co-incubation of CART-123 cells and cytokine-exposed primary AML blasts leads to increased populations of PD-1+/CD39+/CTLA4+/LAG3+ CAR T cells, consistent with an exhaustion phenotype. Finally, we found that anti-apoptotic effects of cytokines can be prevented, and CART-123 killing of AML can be restored, via ruxolitinib blockade of JAK/STAT signaling in both in vitro and in vivo settings. Significance: Our work reveals CRS as active in undermining CART-123 lethality first by promoting survival of AML, and subsequently by exhausting CAR T cells. This is in stark contrast to its role in lymphoid malignancies and underscores biological differences in myeloid versus lymphoid neoplasms. These results highlight a need to tailor therapy to limit cytokine effects on AML blasts to improve outcomes with AML-directed CAR T cell therapy.

The Molecular Pathway of p75 Neurotrophin Receptor (p75NTR) in Parkinson's Disease: The Way of New Inroads.

Parkinson's disease (PD) is a chronic and progressive neurodegenerative disease of the brain. PD is characterized by motor and non-motor symptoms. The p75 neurotrophin receptor (p75NTR) is a functional receptor for different growth factors including pro-brain derived neurotrophic factor (pro-BDNF), neurotrophin 3 (NT-3), and neurotrophin 4 (NT-4). Consequently, this review aimed to illustrate the detrimental and beneficial role of p75NTR in PD. Diverse studies showed that p75NTR and its downstream signaling are intricate in the pathogenesis of PD. Nevertheless, pro-apoptotic and pro-survival pathways mediated by p75NTR in PD were not fully clarified. Of note, p75NTR plays a critical role in the regulation of dopaminergic neuronal survival and apoptosis in the CNS. Particularly, p75NTR can induce selective apoptosis of dopaminergic neurons and progression of PD. In addition, p75NTR signaling inhibits the expression of transcription factors which are essential for the survival of dopaminergic neurons. Also, p75NTR expression is connected with the severity of dopaminergic neuronal injury. These verdicts implicate p75NTR signaling in the pathogenesis of PD, though the underlying mechanistic pathways remain not elucidated. Collectively, the p75NTR signaling pathway induces a double-sword effect either detrimental or beneficial depending on the ligands and status of PD neuropathology. Therefore, p75NTR signaling seems to be protective via phosphoinositide 3-kinase (PI3K)/AKT and Bcl-2 and harmful via activation of JNK, caspase 3, nuclear factor kappa B (NF-κB), and RhoA pathways.

OR05-06 Histone Deacetylase Inhibitor, Panobinostat, In Combination With A Smac-mimetic For The Treatment Of Ovarian Granulosa Cell Tumours

Abstract Disclosure: S. Chu: None. A. Carolan: None. C. Giatrakis: None. T. Nguyen: None. M. Alexiadis: None. T. Yu: None. J. Silke: None. P.J. Fuller: None. Background: Granulosa cell tumours (GCT) are uncommon ovarian cancers characterised by an indolent clinical course and significant late recurrence rates. Aside from invasive surgery, there are limited therapeutic options, highlighting the need for targeted therapies. Our laboratory has previously shown that targeting X-linked Inhibitor of Apoptosis Protein (XIAP) using small molecule inhibitors known as Smac-mimetics (SM) in combination with other compounds, is a compelling therapeutic strategy in GCT. XIAP inhibition sensitises cancer cells to anti-cancer therapies through the regulation of key pro-survival pathways, namely NFκB. Methods: High-throughput screening (HTS) using established drug libraries was performed in a GCT-derived cell line (KGN) and a transformed non-luteinized granulosa cell line (hGrC1), following pre-treatment with the SM, Compound A (CmpdA; 500nM). Drug combination hits were defined as a greater than> 80% reduction in viability compared to CmpdA monotherapy alone. Subsequent validation studies were conducted to measure the effects on cell proliferation, apoptosis, and NFκB transactivation. The impact of the combination therapy was assessed by RNA-seq analysis to identify differentially expressed genes, significant pathways, and functional enrichment. Results: Here we report the use of a histone deacetylase inhibitor (HDACi), panobinostat, in combination with CmpdA, as a potential treatment for GCT. Using cell proliferation and viability assays, we demonstrated that 100nM panobinostat acts synergistically with 500nM CmpdA to significantly decrease cell proliferation and increase apoptosis, as demonstrated by increased caspase 3/7 activity. Apoptotic pathways were further assessed using flow cytometry. A potential mechanism of action for the compounds was tested using real-time PCR and luciferase reporter assays. In KGN cells, panobinostat demonstrated increased NFκB activity and TNFα expression, which decreased when combined with CmpdA, suggesting that there is enhanced activation of the extrinsic pathway of apoptosis. Transcriptomic analysis showed the top significantly enriched pathways related to mechanisms of cancer pathogenesis. In particular, we observed significant downregulation of SIRT1, a non-classical Class III HDAC that is potentially important in GCT tumorigenesis through its interactions with the FOXL2 transcription factor, affecting cancer pathways such as cell senescence, proliferation, and apoptosis. Conclusion: We present a promising combination therapeutic strategy for GCT that reduced cell proliferation, increased apoptosis, and reduced inflammatory gene expression. Further studies are now needed to confirm and translate these findings, and to identify the links between SIRT1, and the pathognomonic FOXL2C134W mutation of GCT. Presentation: Thursday, June 15, 2023

Cerebroprotective Effect of 17β-Estradiol Replacement Therapy in Ovariectomy-Induced Post-Menopausal Rats Subjected to Ischemic Stroke: Role of MAPK/ERK1/2 Pathway and PI3K-Independent Akt Activation.

Despite the overwhelming advances in the understanding of the pathogenesis of stroke, a devastating disease affecting millions of people worldwide, currently there are only a limited number of effective treatments available. Preclinical and clinical studies show that stroke is a sexually dimorphic disorder, affecting males and females differently. Strong experimental evidence indicates that estrogen may play a role in this difference and that exogenous 17β-estradiol (E2) is neuroprotective against stroke in both male and female rodents. However, the molecular mechanisms by which E2 intervenes in ischemia-induced cell death, revealing these sex differences, remain unclear. The present study was aimed to determine, in female rats, the molecular mechanisms of two well-known pro-survival signaling pathways, MAPK/ERK1/2 and PI3K/Akt, that mediate E2 neuroprotection in response to acute ischemic stroke. E2 pretreatment reduced brain damage and attenuated apoptotic cell death in ovariectomized female rats after an ischemic insult. Moreover, E2 decreased phosphorylation of ERK1/2 and prevented ischemia/reperfusion-induced dephosphorylation of both Akt and the pro-apoptotic protein, BAD. However, MAPK/ERK1/2 inhibitor PD98059, but not the PI3K inhibitor LY294002, attenuated E2 neuroprotection. Thus, these results suggested that E2 pretreatment in ovariectomized female rats modulates MAPK/ERK1/2 and activates Akt independently of PI3K to promote cerebroprotection in ischemic stroke. A better understanding of the mechanisms and the influence of E2 in the female sex paves the way for the design of future successful hormone replacement therapies.

Idiopathic pulmonary fibrosis (IPF): disease pathophysiology, targets, and potential therapeutic interventions.

Idiopathic pulmonary fibrosis (IPF) is a progressive, degenerative pulmonary condition. Transforming growth factor (TGF)-β, platelet-derived growth factor (PDGF), and tumor necrosis factor-α (TNF-α) are the major modulators of IPF that mediate myofibroblast differentiation and promote fibrotic remodeling of the lung. Cigarette smoke, asbestos fiber, drugs, and radiation are known to favor fibrotic remodeling of the lungs. Oxidative stress in the endoplasmic reticulum (ER) also leads to protein misfolding and promotes ER stress, which is predominant in IPF. This phenomenon further results in excess reactive oxygen species (ROS) aggregation, increasing oxidative stress. During protein folding in the ER, thiol groups on the cysteine residue are oxidized and disulfide bonds are formed, which leads to the production of hydrogen peroxide (H2O2) as a by-product. With the accumulation of misfolded proteins in the ER, multiple signaling cascades are initiated by the cell, collectively termed as the unfolded protein response (UPR). UPR also induces ROS production within the ER and mitochondria and promotes both pro-apoptotic and pro-survival pathways. The prevalence of post-COVID-19 pulmonary fibrosis (PCPF) is 44.9%, along with an alarming increase in "Coronavirus Disease 2019" (COVID-19) comorbidities. Fibrotic airway remodeling and declined lung function are the common endpoints of SARS-CoV-2 infection and IPF. Flavonoids are available in our dietary supplements and exhibit medicinal properties. Apigenin is a flavonoid found in plants, including chamomile, thyme, parsley, garlic, guava, and broccoli, and regulates several cellular functions, such as oxidative stress, ER stress, and fibrotic responses. In this study, we focus on the IPF and COVID-19 pathogenesis and the potential role of Apigenin in addressing disease progression.

The Apoptosis Inhibitor Protein Survivin Is a Critical Cytoprotective Resistor against Silica-Based Nanotoxicity.

Exposure to nanoparticles is inevitable as they become widely used in industry, cosmetics, and foods. However, knowledge of their (patho)physiological effects on biological entry routes of the human body and their underlying molecular mechanisms is still fragmented. Here, we examined the molecular effects of amorphous silica nanoparticles (aSiNPs) on cell lines mimicking the alveolar-capillary barrier of the lung. After state-of-the-art characterization of the used aSiNPs and the cell model, we performed cell viability-based assays and a protein analysis to determine the aSiNP-induced cell toxicity and underlying signaling mechanisms. We revealed that aSiNPs induce apoptosis in a dose-, time-, and size-dependent manner. aSiNP-induced toxicity involves the inhibition of pro-survival pathways, such as PI3K/AKT and ERK signaling, correlating with reduced expression of the anti-apoptotic protein Survivin on the protein and transcriptional levels. Furthermore, induced Survivin overexpression mediated resistance against aSiNP-toxicity. Thus, we present the first experimental evidence suggesting Survivin as a critical cytoprotective resistor against silica-based nanotoxicity, which may also play a role in responses to other NPs. Although Survivin's relevance as a biomarker for nanotoxicity needs to be demonstrated in vivo, our data give general impetus to investigate the pharmacological modulation of Survivin`s functions to attenuate the harmful effects of acute or chronic inhalative NP exposure.

Regulation and role of the PP2A-B56 holoenzyme family in cancer.

Protein phosphatase 2A (PP2A) inactivation is common in cancer, leading to sustained activation of pro-survival and growth-promoting pathways. PP2A consists of a scaffolding A-subunit, a catalytic C-subunit, and a regulatory B-subunit. The functional complexity of PP2A holoenzymes arises mainly through the vast repertoire of regulatory B-subunits, which determine both their substrate specificity and their subcellular localization. Therefore, a major challenge for developing more effective therapeutic strategies for cancer is to identify the specific PP2A complexes to be targeted. Of note, the development of small molecules specifically directed at PP2A-B56α has opened new therapeutic avenues in both solid and hematological tumors. Here, we focus on the B56/PR61 family of PP2A regulatory subunits, which have a central role in directing PP2A tumor suppressor activity. We provide an overview of the mechanisms controlling the formation and regulation of these complexes, the pathways they control, and the mechanisms underlying their deregulation in cancer.