Aggressive Cell Lines Research Articles

Trpm8 Expression in Human and Mouse Castration Resistant Prostate Adenocarcinoma Paves the Way for the Preclinical Development of TRPM8-Based Targeted Therapies.

Metastatic prostate cancer (mPCa) is one of the leading causes of cancer-related mortality in both the US and Europe. Androgen deprivation is the first-line therapy for mPCa; however, resistance to therapy inevitably occurs and the disease progresses to the castration resistant stage, which is uncurable. A definition of novel targeted therapies is necessary for the establishment of innovative and more effective protocols of personalized oncology. We employed genetically engineered mouse models of PCa and human samples to characterize the expression of the TRPM8 cation channel in both hormone naïve and castration resistant tumors. We show that Trpm8 expression marks both indolent (Pten-null) and aggressive (Pten/Trp53 double-null and TRAMP) mouse prostate adenocarcinomas. Importantly, both mouse and human castration-resistant PCa preserve TRPM8 protein expression. Finally, we tested the effect of TRPM8 agonist D-3263 administration in combination with enzalutamide or docetaxel on the viability of aggressive mouse PCa cell lines. Our data demonstrate that D-3263 substantially enhances the pro-apoptotic activity of enzalutamide and docetaxel in TRAMP-C1 e TRAMP-C2 PCa cell lines. To conclude, this study provides the basis for pre-clinical in vivo testing of TRPM8 targeting as a novel strategy to implement the efficacy of standard-of-care treatments for advanced PCa.

Different Susceptibilities of Human Melanoma Cell Lines to G2/M Blockage and Cell Death Activation in Response to the Estrogen Receptor β agonist LY500307.

Background: Gender differences in melanoma incidence, metastasis formation and disease progression are increasingly evident in epidemiological studies, with women showing significantly better survival than men. Among factors possibly underlying the disparities, sex hormones seem to play a key role. Nonetheless, functional mechanisms are still unclear, except for the antitumor ability of Estrogen Receptor (ER) β, whose expression determination has often been suggested for melanoma prognosis. In this study, we aimed at evaluating the molecular mechanisms and functional effects associated with ERβ signaling by using its agonist LY500307.Methods: We evaluated the antitumor effect of the specific synthetic ERβ agonist LY500307 on some human melanoma cell lines, selected for different genetic background, expression levels of ERs and tumor progression. The expression of α and β estrogen receptors was investigated taking advantage of The Cancer Genome Atlas database and confirmed on some selected melanoma cell lines. The biological effects of LY500307 were determined in vitro looking at melanoma cell proliferation, cell cycle profiles and migration demonstrating by western blot the involvement of some pathway specific markers. The LY500307-dependent induction of cell death was also analyzed by flow cytometry and western blot analysis of caspase 3 and poly adenosine diphosphate-ribose polymerase (PARP).Results: A significant decrease in the expression of both ERs, even more pronounced for ERα, has been found in patients with metastatic NRAS mutation. Treatment with LY500307 significantly reduced the proliferation of melanoma cells showing a cell cycle arrest at the G2/M boundary phase and promoting apoptosis with different sensitivities associated with disease stage and mutation. Indeed, the ERβ agonist affects melanoma migration, inducing a reversion of the epithelial-mesenchymal transition, more evident in a low aggressive primary melanoma cell line.Conclusion: These results demonstrate the capability of LY500307 to reduce melanoma malignancy, counteracting cell viability and dissemination, overall suggesting a possible future use of LY500307 in personalized combined therapy.

Selection of Cancer Stem Cell-Targeting Agents Using Bacteriophage Display.

There is a growing need to develop tumor targeting agents for aggressive cancers. Aggressive cancers frequently relapse and are resistant to various therapies. Cancer stem cells (CSCs) are believed to be the cause of relapse and the aggressive nature of many cancers. Targeting CSCs could lead to novel diagnostic and treatment options. Bacteriophage (phage) display is a powerful tool developed by George Smith in 1985 to aid in the discovery of CSC targeting agents. Phage display selections are typically performed in vitro against an immobilized target. There are inherent disadvantages with this technique that can be circumvented by performing phage display selections in vivo. However, in vivo phage display selections present new challenges. A combination of both in vitro and in vivo selections, however, can take advantage of both selection methods. In this chapter, we discuss in detail how to isolate a CSC like population of cells from an aggressive cancer cell line, perform in vivo and in vitro phage display selections against the CSCs, and then characterize the resulting phage/peptides for further use as a diagnostic and therapeutic tool.

Increased Expression of Flightless I in Cutaneous Squamous Cell Carcinoma Affects Wnt/β-Catenin Signaling Pathway.

Cutaneous squamous cell carcinoma (cSCC) accounts for 25% of cutaneous malignancies diagnosed in Caucasian populations. Surgical removal in combination with radiation and chemotherapy are effective treatments for cSCC. Nevertheless, the aggressive metastatic forms of cSCC still have a relatively poor patient outcome. Studies have linked actin cytoskeletal dynamics and the Wnt/β-catenin signaling pathway as important modulators of cSCC pathogenesis. Previous studies have also shown that the actin-remodeling protein Flightless (Flii) is a negative regulator of cSCC. The aim of this study was to investigate if the functional effects of Flii on cSCC involve the Wnt/β-catenin signaling pathway. Flii knockdown was performed using siRNA in a human late stage aggressive metastatic cSCC cell line (MET-1) alongside analysis of Flii genetic murine models of 3-methylcholanthrene induced cSCC. Flii was increased in a MET-1 cSCC cell line and reducing Flii expression led to fewer PCNA positive cells and a concomitant reduction in cellular proliferation and symmetrical division. Knockdown of Flii led to decreased β-catenin and a decrease in the expression of the downstream effector of β-catenin signaling protein SOX9. 3-Methylcholanthrene (MCA)-induced cSCC in Flii overexpressing mice showed increased markers of cancer metastasis including talin and keratin-14 and a significant increase in SOX9 alongside a reduction in Flii associated protein (Flap-1). Taken together, this study demonstrates a role for Flii in regulating proteins involved in cSCC proliferation and tumor progression and suggests a potential role for Flii in aggressive metastatic cSCC.

Development of a Prognostic Model Based on the Identification of EMT-Related lncRNAs in Triple-Negative Breast Cancer.

Background Triple-negative breast cancer (TNBC) remains the most incurable subtype of breast cancer owing to high heterogeneity, aggressive nature, and lack of treatment options. It is generally acknowledged that epithelial-mesenchymal transition (EMT) is the key step in tumor metastasis. Methods With the application of TCGA and GEO databases, we identified EMT-related lncRNAs by the Cox univariate regression analysis. Optimum risk scores were calculated and used to divide TNBC patients into high-/low-risk subgroups by the median value using the Lasso regression analysis. The Kaplan–Meier and ROC curve analyses were applied for model validation. Then, we assessed the risk model from multi-omic aspects including immune infiltration, drug sensitivity, mutability spectrum, signaling pathways, and clinical indicators. We also analyzed the expression pattern of lncRNAs involved in the model using qRT-PCR in TNBC cell lines and constructed the ceRNA network. Results The risk model was composed of EMT-related long noncoding RNAs (lncRNAs), which seemed to be valuable in the prognostic prediction of TNBC patients. The model could act as an independent prognostic factor of TNBC and showed a robust prognostic ability in the stratification analysis. Further investigation demonstrated that the expression of lncRNAs was different between high aggressive and low aggressive TNBC cell lines, as well as TNBC patients. Conclusions Together, our study successfully established a risk model with great accuracy and efficacy in the prognostic prediction of TNBC patients.

Circular RNA circHERC4 as a novel oncogenic driver to promote tumor metastasis via the miR-556-5p/CTBP2/E-cadherin axis in colorectal cancer

BackgroundThe main cause of death in colorectal cancer patients is metastasis. Accumulating evidences suggest that circRNA plays pivotal roles in cancer initiation and development. However, the underlying molecular mechanisms of circRNAs that orchestrate cancer metastasis remain vague and need further clarification.MethodsTwo paired CRC and adjacent normal tissues were used to screen the upregulated circRNAs by circRNA-seq; then, cell invasion assay was applied to confirm the functional invasion-related circRNAs. According to the above methods, circHERC4 (hsa_circ_0007113) was selected for further research. Next, we investigated the clinical significance of circHERC4 in a large cohort of patients with CRC. The oncogenic activity of circHERC4 was investigated in both CRC cell lines and animal xenograft studies. Finally, we explored the molecular mechanisms underlying circHERC4 as a malignant driver.ResultsWe demonstrated that circHERC4 was aberrantly elevated in CRC tissues (P < 0.001), and was positively associated with lymph node metastasis and advanced tumor grade (P < 0.01). Notably, the expression of circHERC4 was associated with worse survival in patients with CRC. Silencing of circHERC4 significantly inhibited the proliferation and migration of two highly aggressive CRC cell lines and reduced liver and lung metastasis in vivo. Mechanistically, we revealed that circHERC4 inactivated the tumor suppressor, miR-556-5p, leading to the activation of CTBP2/E-cadherin pathway which promotes tumor metastasis in CRC.ConclusionsCircHERC4 exerts critical roles in promoting tumor aggressiveness through miR-556-5p/CTBP2/E-cadherin pathway and is a prognostic biomarker of the disease, suggesting that circHERC4 may serve as an exploitable therapeutic target for patients with CRC.

Antioxidant and antibacterial activities of Artemisia absinthium and Citrus paradisi extracts repress viability of aggressive liver cancer cell line.

Numerous reports show that herbal medicines can be utilized in the treatment of different liver disorders. In this study, antioxidant, antibacterial, and anticancer activities of individual as well as combined 80% ethanolic extracts of Artemisia absinthium leaves and Citrus paradisi peels were investigated. Values of total phenolic contents (TPC), total flavonoid contents (TFC), DPPH-radical scavenging activity, and ferric reducing antioxidant power (FRAP) were measured to explore the antioxidant capacity. To assess antibacterial activity, four bacterial strains (Escherichia coli, Staphylococcus aureus, Salmonella enterica, and Klebsiella pneumoniae) were used. Anticancer activity was assessed on Huh-7 (liver cancer) and Vero (non-cancerous) cell lines. FRAP activity of combined plants extract was higher as compared to their individual effect; the trend did not hold in the case of DPPH-radical scavenging activity. Antibacterial activity of combined extracts by disk diffusion method was observed only against E.coli. MTT results indicated that both plants had a cytotoxic effect on Huh-7 cell line but did not show any effect on Vero cell line. Our data showed a strong negative correlation between the amount of TPC, TFC, & DPPH radicals-scavenging activity and viability of Huh-7 cell line.However, no effect was shown on the non-cancerous cell line. The ethanolic extracts of Artemisia absinthium leaves and Citrus paradisi peels can be used against liver cancer because of their antioxidant, antibacterial, and anticancer activities.

A Novel Aggressive NK Cell Leukemia Cell Line and Mouse Model for Evaluation of Therapeutic Candidates

Introduction: Aggressive nature killer-cell leukemia (ANKL) is a rare, highly lethal and disseminated malignancy derived from NK cells. Patients are most commonly young to middle aged adults who present with constitutional symptoms and often have organomegaly, hemophagocytosis, and multiorgan failure. Most cases are refractory to therapy and the median survival is less than 2 months despite multiagent chemotherapy. Development model systems and novel targeted therapeutic agents remains an urgent issue. In this study we established a cell line and a NOD-scid IL2Rgammanull(NSG) mouse model of ANKL, which represented the primary malignant cells. We characterized the molecular features of this model and explored new targeted agents against it.Methods: Primary tumor cells were cultured ex vivo in the presence of human IL-2 and then injected into a NSG mouse. Flow cytometry, immunohistochemistry (IHC), CISH-EBER were used to confirm the engraftment and to compare the pathologic features of engrafted tumor cells with the primary sample. Karyotyping and oligonucleotide/single nucleotide polymorphism microarray analyses were performed to compare the established cell line CCANKL with primary tumor cells. Selective inhibitors targeting anti-apoptotic BCL-2 family members and a CD6-targeted antibody drug conjugate (ADC) were tested for their treatment efficacies in this model.Results: Leukemic peripheral blood from a 31-year old woman with relapsed ANKL demonstrated a hyperleukocytosis in which NK cells accounted for 88% of cells. Immunophenotyping showed the malignant cells expressed CD2, 7, 38, 45 and 56, and lacked CD3, 4, 5, 8, 10, 11b, 13, 14, 16, 19, 20, 22, 33, 34, 57, 64, 65, 117, HLADR and Kappa or Lambda immunoglobulin light chain. IHC of an involved lymph node showed the presence of EBV (EBER in situ hybridization) and a proliferative index of 70%. Isolated PBMC were cultured ex vivo and serially passaged as a cell line (CCANKL) in the presence of human IL2. CCANKL cells successfully engrafted in NSG mice and displayed splenomegaly. IHC and Immunophenotyping data confirmed both CCANKL cells and engrafted cells in NSG mice represented primary tumor cells. Both the primary PBMC and CCANKL cells had similar, abnormal karyotypes of 46,XX,dup(1)(q21q42), del(6)(q15q25)[1]/46,idem,der(20)t(7;20)(q11.2;q13.1)[9] and 46,XX,del(6)(q15q25),der(20)t(7;20)(q11.2;q13.1),add(22)(p11.1)[10], respectively. Microarray analysis of both primary tumor cells and CCANKL confirmed some of the karyotypic findings, but also revealed additional abnormalities, in particular for the CCANKL cell line. There were also some differences for the copy number changes and regions of loss of heterozygosity observed between the primary tumor cells and CCANKL. Abnormalities involving 1q, 6q and 7p have been reported in association with aggressive NK cell leukemia.Both immunoblotting and IHC revealed expression of anti-apoptotic proteins of BCL-xL, MCL-1 and pro-apoptotic BIM in CCANKL cells and NSG-engrafted tumors, while BCL-2 was positive in cultured cells by Western blotting but not detectable in engrafted tissue via IHC. Expression level of BCL-xl was stable but there were enhanced expression of MCL-1 and BIM during 72-hour starvation of IL2 in cultured CCANKL cells. Single agent of venetoclax, BCL-xl inhibitor (A-1331852), and CDK9 inhibitor (A-1592668), at range of 1 - 1000 nM, had no detectable (BCL-2), mild (BCL-xL), and strong (CDK9) killing activities against CCANKL cells.We further confirmed expression of CD6, a surface glycoprotein expressed on most T-cells and a subset of NK cells, by IHC and flow cytometry in CCANKL and also tested a novel CD6-targeted ADC. Compared to naked anti-CD6 IgG and isotype control, CD6-ADC was capable of inducing apoptosis in CCANKL cells. Administration of either anti-CD6 IgG or CD6-ADC (4 mg/kg) on the same day as inoculation of CCANKL cells in NSG mice blocked engraftment of these malignant cells in NSG mice. The 2 nd ANKL case tested by IHC showed positive of CD6 in malignant cells.Conclusion: A novel aggressive NK cell leukemia cell line and a NSG mouse model were established. The in vitro data support further investigation of the expression features of BCL-2 family proteins in ANKL cases and in vivo evaluation for the efficiency of anti-apoptotic protein inhibitors in this aggressive disease. Further studies targeting CD6 in ANKL is warranted. DisclosuresLin: Takeda Pharma: Consultancy, Research Funding. Phillips: AbbVie Inc.: Current Employment, Current equity holder in publicly-traded company. Hsi: AbbVie Inc, Eli Lilly: Research Funding.

The Sumoylation Inhibitor TAK-981 in Combination with the CD19-Targeting Antibody Tafasitamab Shows Enhanced Anti-Tumor Activity in Preclinical B-Cell Lymphoma Models

IntroductionTAK-981 is a first-in-class small molecule inhibitor of the SUMO activating enzyme currently in Phase I/II clinical trials. TAK-981 has been shown to increase NK cell activation and M1 macrophage polarization via upregulation of Type I interferon (IFN) signaling, leading to enhanced antibody-dependent cellular cytotoxicity (ADCC) and antibody-dependent cellular phagocytosis (ADCP) in combination with rituximab (Nakamura 2019, AACR).Tafasitamab (MOR208) is a CD19-targeting antibody with enhanced Fc effector function mediating ADCC, ADCP and direct cytotoxic activities against B-lymphoma cells. Based on the Phase II clinical study L-MIND (Salles et al., 2020 and Duell et al., 2021), tafasitamab in combination with lenalidomide received accelerated approval by the Food and Drug Administration for the treatment of transplant-ineligible adult patients with relapsed or refractory (R/R) diffuse large B-cell lymphoma (DLBCL).Due to the potential for TAK-981 to enhance the activity of tafasitamab via activation of innate effector cells, we aimed to investigate the effects of this drug combination on ADCC, ADCP and tumor cell viability in vitro. Additionally, combinatorial activity of TAK-981 plus tafasitamab was evaluated in lymphoma xenograft models.MethodsA panel of 9 aggressive lymphoma cell lines was analyzed (7 DLBCL and 2 Burkitt lymphoma). For ADCC, PBMC effector cells from healthy human donors were pre-treated with 0.1 or 1 µM TAK-981 or dimethyl sulfoxide (DMSO) control for 24 hours. Tumor cells were incubated with/without 1 nM tafasitamab in the presence of TAK-981 pretreated PBMCs at effector-to-target (E:T) ratios of 5:1 to 10:1 for 2 hours. Degranulation of NK cells was determined via CD107a surface expression after co-incubation of TAK-981 pre-treated PBMCs with tumor cells and 0.1 or 10 nM tafasitamab for 3 hours. Cytokine levels in the supernatant were investigated upon incubation of PBMCs with lymphoma cells, 1 µM TAK-981 and/or 10 nM tafasitamab for 24 hours. For the ADCP assays, in vitro differentiated macrophages were treated with 1 µM TAK-981 for 24 hours. Next, macrophages were incubated with lymphoma cells and 1 or 10 nM tafasitamab at an E:T ratio of 2:1 for 3 hours. For cell viability assays, tumor cells were treated with 1-1000 nM TAK-981 and/or 5 nM tafasitamab for 24 hours in the absence of effector cells. Cytotoxicity, phagocytosis, degranulation and cytokine release were analyzed by flow cytometry. Cell viability was assessed by determination of ATP levels. For in vivo analysis, effects of TAK-981 (7.5 mg/kg IV twice weekly) in combination with tafasitamab (3, 10 or 20 mg/kg IP twice weekly) on tumor growth were evaluated in Daudi and WSU-DLCL2 xenograft models of Burkitt lymphoma and DLBCL grown in SCID mice.ResultsIn ADCC experiments, increased cytotoxicity was observed upon combination treatment with TAK-981 and tafasitamab compared to the respective mono treatments in 5/8 tested lymphoma cell lines (Daudi, SU-DHL-2, SU-DHL-6, TMD8, OCI-LY10). Moreover, TAK-981 plus tafasitamab enhanced degranulation of NK cells and cytokine release compared to mono treatments. In ADCP assays, combination of TAK-981 and tafasitamab resulted in increased phagocytosis rates in comparison to mono treatments in 2/2 tested cell lines (Daudi, Ramos). Cell viability analysis revealed a combination benefit by increased direct cytotoxic effects against SU-DHL-6 cells. Finally, TAK-981 and tafasitamab were investigated in Daudi and WSU-DLCL2 xenograft models with 3 weeks of dosing. In the Daudi model, the combination treatments of TAK-981 with 10 or 20 mg/kg tafasitamab performed better than either treatment alone, and in the WSU-DLCL2 model, the combination treatments of TAK-981 with 3, 10 or 20 mg/kg tafasitamab performed better than the single agent treatments.ConclusionsThe combination of TAK-981 with tafasitamab significantly enhanced anti-tumor effects compared to the respective monotherapies in vitro and in vivo. These preclinical data support a clinical evaluation of this drug combination in patients with lymphoma including aggressive subtypes such as Burkitt lymphoma and DLBCL.The study was funded by MorphoSys AG and Takeda Development Center Americas, Inc. DisclosuresPatra-Kneuer: MorphoSys AG: Current Employment. Nakamura: Takeda Development Center Americas, Inc.: Current Employment. Song: Takeda Pharmaceuticals International Co.: Current Employment. Grossman: Takeda Development Center, Cambridge MA: Current Employment. Polzer: MorphoSys: Current Employment. Ginzel: MorphoSys: Current Employment. Steidl: MorphoSys AG: Current Employment. Berger: Takeda Development Center Americas, Inc.: Current Employment. Proscurshim: Takeda Pharmaceuticals: Current Employment, Current holder of individual stocks in a privately-held company. Heitmüller: MorphoSys AG: Current Employment.

Alteration of miR-362-5p and miR-454-3p expression elicits diverse responses in breast cancer cell lines.

The heterogeneity of breast tumors presents a challenge in disease management, necessitating an understanding of the molecular mechanisms driving breast tumorigenesis. Aberrant expression of microRNAs is known to promote tumor growth and progression. Our previous RNA-sequencing dataset revealed the upregulation of miR-362-5p and miR-454-3p in breast tumors. We investigated potential role of miR-362-5p and miR-454-3p in breast cancer using MDAMB231 and MCF7 cell lines. The expression of miR-362-5p and miR-454-3p were altered in MCF7 and MDAMB231 using mimics and inhibitors. The effect on cell viability, cell cycle progression and migration was assessed using Alamar blue assay, flow cytometry and wound healing assay. Further, the expression of potential target genes were measured using real-time PCR. Our results indicated that an increased expression of miR-362-5p promoted cell growth and survival in MCF7, but decreased cell migration. In contrast, miR-362-5p overexpression reduced cancer cell growth, survival and migration in MDAMB231. Overexpression of miR-454-3p was oncogenic in both cell lines but suppressed migration in the aggressive cell line MDAMB231. Two microRNAs, miR-362-5p and miR-454-3p, were evaluated for functional activity in breast cancer cell lines and they showed increased proliferative signals and tumorigenic properties.

Normal Skin Cells Increase Aggressiveness of Cutaneous Melanoma by Promoting Epithelial-to-Mesenchymal Transition via Nodal and Wnt Activity.

Melanoma is a lethal form of skin cancer triggered by genetic and environmental factors. Excision of early-stage, poorly aggressive melanoma often leads to a successful outcome; however, left undiagnosed these lesions can progress to metastatic disease. This research investigates whether the exposure of poorly aggressive melanoma to certain normal skin cells can explain how non-metastatic melanoma becomes more aggressive while still confined to the skin. To this end, we used a serial co-culture approach to sequentially expose cells from two different, poorly aggressive human melanoma cell lines against normal cells of the skin beginning with normal melanocytes, then epidermal keratinocytes, and finally dermal fibroblasts. Protein extraction of melanoma cells occurred at each step of the co-culture sequence for western blot (WB) analysis. In addition, morphological and functional changes were assessed to detect differences between the serially co-cultured melanoma cells and non-co-cultured cells. Results show that the co-cultured melanoma cells assumed a more mesenchymal morphology and displayed a significant increase in proliferation and invasiveness compared to control or reference cells. WB analysis of protein from the co-cultured melanoma cells showed increased expression of Snail and decreased levels of E-cadherin suggesting that epithelial-to-mesenchymal transition (EMT) is occurring in these co-cultured cells. Additional WB analysis showed increased levels of Nodal protein and signaling and signs of increased Wnt activity in the co-cultured melanoma cells compared to reference cells. These data suggest that interaction between poorly aggressive melanoma cells with normal cells of the skin may regulate the transition from localized, poorly aggressive melanoma to invasive, metastatic disease via Nodal and/or Wnt induced EMT.

Neuroblastoma xenograft models demonstrate the therapeutic potential of 177Lu-octreotate

BackgroundNeuroblastoma (NB) is one of the most frequently diagnosed tumors in infants. NB is a neuroendocrine tumor type with various characteristics and features, and with diverse outcome. The most malignant NBs have a 5-year survival rate of only 40–50%, indicating the need for novel and improved treatment options. 177Lu-octreotate is routinely administered for treatment of neuroendocrine tumors overexpressing somatostatin receptors (SSTR). The aim of this study was to examine the biodistribution of 177Lu-octreotate in mice bearing aggressive human NB cell lines, in order to evaluate the potential usefulness of 177Lu-octreotate for treatment of NB.MethodsBALB/c nude mice bearing CLB-BAR, CLB-GE or IMR-32 tumor xenografts (n = 5–7/group) were i.v. injected with 0.15 MBq, 1.5 MBq or 15 MBq 177Lu-octreotate and sacrificed 1 h, 24 h, 48 h and 168 h after administration. The radioactivity concentration was determined for collected tissue samples, tumor-to-normal-tissue activity concentration ratios (T/N) and mean absorbed dose for each tissue were calculated. Immunohistochemical (IHC) staining for SSTR1–5, and Ki67 were carried out for tumor xenografts from the three cell lines.ResultsHigh 177Lu concentration levels and T/N values were observed in all NB tumors, with the highest for CLB-GE tumor xenografts (72%IA/g 24 h p.i.; 1.5 MBq 177Lu-octreotate). The mean absorbed dose to the tumor was 6.8 Gy, 54 Gy and 29 Gy for CLB-BAR, CLB-GE and IMR-32, respectively, p.i. of 15 MBq 177Lu-octreotate. Receptor saturation was clearly observed in CLB-BAR, resulting in higher concentration levels in the tumor when lower activity levels where administered. IHC staining demonstrated highest expression of SSTR2 in CLB-GE, followed by CLB-BAR and IMR-32.ConclusionT/N values for all three human NB tumor xenograft types investigated were high relative to previously investigated neuroendocrine tumor types. The results indicate a clear potential of 177Lu-octreotate as a therapeutic alternative for metastatic NB.

Anti-CD19 CAR T Cells That Secrete a Biparatopic Anti-CLEC12A Bridging Protein Have Potent Activity Against Highly Aggressive Acute Myeloid Leukemia In Vitro and In Vivo.

Refractory acute myeloid leukemia (AML) remains an incurable malignancy despite the clinical use of novel targeted therapies, new antibody-based therapies, and cellular therapeutics. Here, we describe the preclinical development of a novel cell therapy that targets the antigen CLEC12A with a biparatopic bridging protein. Bridging proteins are designed as "CAR-T cell engagers," with a CAR-targeted protein fused to antigen binding domains derived from antibodies. Here, we created a CD19-anti-CLEC12A bridging protein that binds to CAR19 T cells and to the antigen CLEC12A. Biparatopic targeting increases the potency of bridging protein-mediated cytotoxicity by CAR19 T cells. Using CAR19 T cells that secrete the bridging protein we demonstrate potent activity against aggressive leukemic cell lines in vivo This CAR-engager platform is facile and modular, as illustrated by activity of a dual-antigen bridging protein targeting CLEC12A and CD33, designed to counter tumor heterogeneity and antigen escape, and created without the need for extensive CAR T-cell genetic engineering. CAR19 T cells provide an optimal cell therapy platform with well-understood inherent persistence and fitness characteristics.

Abstract 1238: Treating estrogen receptor (ER)-negative and triple-negative breast cancer by targeting STAT3 signaling with putative STAT3 inhibitors

Abstract Approximately 20% to a quarter of breast cancer cases are estrogen receptor (ER)-negative breast cancer (ENBC), including the most aggressive subtype, triple-negative breast cancer (TNBC), which spreads early and shows poor prognosis. ENBCs do not respond to selective ER modulators such as tamoxifen. Therefore, there is an urgent need for non-ER-based therapies for ENBC. Recently, STAT3 was found to play an important role in maintaining cancer stem cells in vitro and in mouse models of human cancers. In addition, during mammary carcinogenesis, STAT3 is highly activated in mammary epithelial cells involving in mammary epithelial cell transformation, tumor initiation, progression, and metastasis. STAT3 has been traditionally considered as non-targetable or undruggable, and there is currently a lack of FDA-approved STAT3 inhibitors for clinical use. We recently developed a putative STAT3 inhibitor, HJC0152, and a series of HJC0152-based analogues as orally bioavailable STAT3 inhibitors. These small molecules have been evaluated and a number of them showed low micro-molar potency in inhibiting the proliferation of a panel of breast cancer cell lines. Compound JMX0804 showed improved anti-proliferative effects against the highly aggressive TNBC cell line MDA-MB-231 and other ER+ and ER- breast cancer cell lines in comparison to HJC0152. JMX0804 inhibited STAT3 phosphorylation at the Tyr705 residue and induced apoptosis in MDA-MB-231 cells. In vivo, mice treated with JMX0804 at a 10 mg/kg dose via i.p. showed reduced growth of xenograft tumors arisen from MDA-MB-231 cells, with minimal impact on general health and body weight. Our current research supports the notion that JMX0804 suppresses breast cancer growth by inhibiting breast cancer cell proliferation and inducing apoptosis via mediating STAT3 signaling. JMX0804 is currently undergoing further characterization for breast cancer metastasis and mechanisms of action as well as optimization to improve drug properties including potency and safety profile. This work is supported by NIH/NCI grant R01 CA231150. Citation Format: Hyejin Kim, Doerte R. Fricke, Jimin Xu, Haiying Chen, Jia Zhou, Qiang Shen. Treating estrogen receptor (ER)-negative and triple-negative breast cancer by targeting STAT3 signaling with putative STAT3 inhibitors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1238.

Abstract 1486: Inhibition of host PI3K-gamma modulates anti-tumor immunity in poorly immunogenic HNSCC

Abstract HNSCC is the 6th most common cancer, with around 650,000 new cases yearly. Gain of function mutations in the PI3K pathway are common in HNSCC, and inhibition of the PI3K p110γ subunit has shown promise in HNSCC treatment. However, given that PI3K p110γ plays an important role in myeloid and lymphoid immune cell function, it is essential to understand how PI3K p110γ inhibition affects the anti-tumor immune response independent of tumor cells. To elucidate PI3K p110γ function in HNSCC, we employed an orthotopic mouse model using poorly immunogenic and aggressive cell line MOC2 on Pik3cg-/- mice. We observed that wild-type and Pik3cg-/- mice displayed similar rates of HNSCC tumor growth and metastasis after 20 days post tumor injection. T cell infiltration and intrinsic T cell responses to MOC2 oral tumors were comparable between wild-type and Pik3cg-/- mice. Interestingly, the immune response of tumor-bearing Pik3cg-/- mice was marked by increased anti-tumor cytotoxic molecules (IFN-γ, IL-17, PD-1) by T cells, and immune checkpoint marker (PD-L1) expression by myeloid cells compared to tumor bearing wild type mice. Taken together, our findings demonstrate that inhibition of PI3K p110γ modulates tumor associated immune cells, which likely potentiates HNSCC treatment when used in combination with selective PD-L1 inhibitors. Citation Format: Kelvin Anderson, Nathan Ryan, Anastasia Alkhimovitch, Arham Siddiqui, Steve Oghumu. Inhibition of host PI3K-gamma modulates anti-tumor immunity in poorly immunogenic HNSCC [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1486.

Atovaquone Suppresses the Growth of Metastatic Triple-Negative Breast Tumors in Lungs and Brain by Inhibiting Integrin/FAK Signaling Axis.

Triple-negative breast cancer (TNBC) is considered to be the most aggressive and malignant neoplasm and is highly metastatic in nature. In the current study, we investigated the anti-metastatic potential of atovaquone, a protozoal drug prescribed for Pneumocystis pneumonia. We showed that atovaquone induced apoptosis and reduced the survival of several aggressive metastatic TNBC cell lines including metastatic patient-derived cells by reducing the expression of integrin α6, integrin β4, FAK, Src, and Vimentin. In order to study the efficacy of atovaquone in suppressing metastasized breast tumor cells in brain and lungs, we performed three in vivo experiments. We demonstrated that oral administration of 50 mg/kg of atovaquone suppressed MDA-MB-231 breast tumor growth by 90% in lungs in an intravenous metastatic tumor model. Anti-metastatic effect of atovaquone was further determined by intracardiac injection of 4T1-luc breast tumor cells into the left ventricle of mouse heart. Our results showed that atovaquone treatment suppressed the growth of metastatic tumors in lungs, liver and brain by 70%, 50% and 30% respectively. In an intracranial model, the growth of HCC1806-luc brain tumors in atovaquone treated mice was about 55% less than that of control. Taken together, our results indicate the anti-metastatic effects of atovaquone in vitro and in vivo in various breast tumor metastasis models.

Edelfosine nanoemulsions inhibit tumor growth of triple negative breast cancer in zebrafish xenograft model

Triple negative breast cancer (TNBC) is known for being very aggressive, heterogeneous and highly metastatic. The standard of care treatment is still chemotherapy, with adjacent toxicity and low efficacy, highlighting the need for alternative and more effective therapeutic strategies. Edelfosine, an alkyl-lysophospholipid, has proved to be a promising therapy for several cancer types, upon delivery in lipid nanoparticles. Therefore, the objective of this work was to explore the potential of edelfosine for the treatment of TNBC. Edelfosine nanoemulsions (ET-NEs) composed by edelfosine, Miglyol 812 and phosphatidylcholine as excipients, due to their good safety profile, presented an average size of about 120 nm and a neutral zeta potential, and were stable in biorelevant media. The ability of ET-NEs to interrupt tumor growth in TNBC was demonstrated both in vitro, using a highly aggressive and invasive TNBC cell line, and in vivo, using zebrafish embryos. Importantly, ET-NEs were able to penetrate through the skin barrier of MDA-MB 231 xenografted zebrafish embryos, into the yolk sac, leading to an effective decrease of highly aggressive and invasive tumoral cells’ proliferation. Altogether the results demonstrate the potential of ET-NEs for the development of new therapeutic approaches for TNBC.

Polyphenolic Compounds of Crataegus Berry, Leaf, and Flower Extracts Affect Viability and Invasive Potential of Human Glioblastoma Cells.

Crataegus contains numerous health-promoting compounds that are also proposed to have anti-cancer properties. Herein, we aimed at a contemporaneous evaluation of the effects of polyphenol-rich extracts of berries, leaves, and flowers of six Crataegus species on the viability and invasive potential on the highly aggressive human glioblastoma U87MG cell line. The treatment with the extracts evoked cytotoxic effects, with the strongest in the berry extracts. All extracts not only promoted the apoptosis-related cleavage of poly (ADP-ribose) polymerase 1 (PARP1) but also substantially inhibited the activity of pro-survival kinases, focal adhesion kinase (FAK), and protein kinase B (PKB; also known as Akt), thus indicating the suppression of proliferative and invasive potentials of the examined glioblastoma cells. The qualitative and quantitative characterization of the extracts’ content was also performed and revealed that amongst 37 polyphenolic compounds identified in the examined Crataegus extracts, the majority (29) was detected in berries; the leaf and flower extracts, exerting milder cytotoxic effects, contained only 14 and 13 compounds, respectively. The highest polyphenol content was found in the berries of C. laevigata x rhipidophylla x monogyna, in which flavan-3-ols and phenolic acids predominated. Our results demonstrated that a high content of polyphenolic compounds correlated with the extract cytotoxicity, and especially berries were a valuable source of compounds with anti-cancer potential. This might be a promising option for the development of an effective therapeutic strategy against highly malignant glioblastomas in the future.

Evofosfamide Is Effective against Pediatric Aggressive Glioma Cell Lines in Hypoxic Conditions and Potentiates the Effect of Cytotoxic Chemotherapy and Ionizing Radiations.

Simple SummaryDespite many therapeutic approaches attempted over the last years, the prognosis of children with high-grade glioma or diffuse intrinsic pontine glioma remains dismal. Hypoxia-activated prodrugs (HAPs) were developed to target hypoxic areas within solid tumors as gliomas. Evofosfamide (Evo) is a 2nd generation HAP exhibiting significant preclinical and clinical activities against adult glioblastoma. We thus investigated the potential of Evo in six pediatric glioma cell lines. Interestingly, we showed that the growth of all cell lines was inhibited by Evo, mainly under hypoxia as expected. We also evidenced a significant synergism between Evo and three drugs widely used in pediatric oncology. Finally, Evo appeared able to potentiate the effect of ionizing radiations. Since these tumors are highly hypoxic and Evo appears effective in hypoxic glioma cells as a single drug and in combination with radio- and chemotherapy, hypoxia-activated prodrugs could represent a promising therapeutic option for children with brain tumors.Hypoxia is a hallmark of many solid tumors and is associated with resistance to anticancer treatments. Hypoxia-activated prodrugs (HAPs) were developed to target the hypoxic regions of these tumors. Among 2nd generation HAPs, Evofosfamide (Evo, also known as TH-302) exhibits preclinical and clinical activities against adult glioblastoma. In this study, we evaluated its potential in the field of pediatric neuro-oncology. We assessed the efficacy of Evo in vitro as a single drug, or in combination with SN38, doxorubicin, and etoposide, against three pediatric high-grade glioma (pHGG) and three diffuse intrinsic pontine glioma (DIPG) cell lines under hypoxic conditions. We also investigated radio-sensitizing effects using clonogenic assays. Evo inhibited the growth of all cell lines, mainly under hypoxia. We also highlighted a significant synergism between Evo and doxorubicin, SN38, or etoposide. Finally, Evo radio-sensitized the pHGG cell line tested, both with fractionated and single-dose irradiation schedules. Altogether, we report here the first preclinical proof of evidence about Evofosfamide efficiency against hypoxic pHGG and DIPG cells. Since such tumors are highly hypoxic, and Evo potentiates the effect of ionizing radiation and chemotherapy, it appears as a promising therapeutic strategy for children with brain tumors.

Cannabidiol Treatment Results in a Common Gene Expression Response Across Aggressive Cancer Cells from Various Origins.

Background: We previously reported that cannabidiol (CBD), a cannabinoid with a low toxicity profile, downregulated the expression of the prometastatic gene inhibitor of DNA binding 1 (ID1) in cancer cells, leading to inhibition of tumor progression in vivo. While CBD is broadly used, including in the self-medication of cancer patients, and CBD-based therapies are undergoing clinical evaluation for cancer treatment, its mechanisms of action are still poorly understood. Methods: In this study, using microarray analysis and Western blot analysis for validation, we attempted to identify the full spectrum of genes regulated by CBD across various aggressive cancer cell lines, including the breast, brain, head and neck, and prostate. Results: We confirmed that ID1 was a major target downregulated by CBD and also discovered that CBD inhibited FOXM1 (Forkhead box M1), a transcriptional activator involved in cell proliferation, while simultaneously upregulating GDF15 (growth differentiation factor 15), a cytokine associated with tissue differentiation. Conclusion: Our results suggest that, by modulating expression of shared key cancer-driving genes, CBD could represent a promising nontoxic therapeutic for treating tumors of various origins.