Growth Of Xenograft Tumors In Mice Research Articles

Shikonin reduces M2 macrophage population in ovarian cancer by repressing exosome production and the exosomal galectin 3-mediated β-catenin activation

BackgroundShikonin (SK), a naphthoquinone with anti-tumor effects, has been found to decrease production of tumor-associated exosomes (exo). This study aims to verify the treatment effect of SK on ovarian cancer (OC) cells, especially on the production of exo and their subsequent effect on macrophage polarization.MethodsOC cells SKOV3 and A2780 were treated with SK. The exo were isolated from OC cells with or without SK treatment, termed OC exo and SK OC exo, respectively. These exo were used to treat PMA-induced THP-1 cells (M0 macrophages). M2 polarization of macrophages was determined by measuring the M2 specific cell surface markers CD163 and CD206 as well as the secretion of M2 cytokine IL-10. The functions of galectin 3 (LGALS3/GAL3) and β-catenin in macrophage polarization were determined by gain- or loss-of-function assays. CB-17 SCID mice were subcutaneously injected with SKOV3 cells to generate xenograft tumors, followed by OC exo or SK OC exo treatment for in vivo experiments.ResultsSK suppressed viability, migration and invasion, and apoptosis resistance of OC cells in vitro. Compared to OC exo, SK OC exo reduced the M2 polarization of macrophages. Regarding the mechanism, SK reduced exo production in cancer cells, and it decreased the protein level of GAL3 in exo and recipient macrophages, leading to decreased β-catenin activation. M2 polarization of macrophages was restored by LGALS3 overexpression but decreased again by the β-catenin inhibitor FH535. Compared to OC exo, the SK OC exo treatment reduced the xenograft tumor growth in mice, and it decreased the M2 macrophage infiltration within tumor tissues.ConclusionThis study suggests that SK reduces M2 macrophage population in OC by repressing exo production and blocking exosomal GAL3-mediated β-catenin activation.

A next-generation BRAF inhibitor overcomes resistance to BRAF inhibition in patients with BRAF-mutant cancers using pharmacokinetics-informed dose escalation.

RAF inhibitors have transformed treatment for BRAF V600-mutant cancer patients, but clinical benefit is limited by adaptive induction of ERK signaling, genetic alterations that induce BRAF V600 dimerization, and poor brain penetration. Next-generation pan-RAF dimer inhibitors are limited by narrow therapeutic index. PF-07799933 (ARRY-440) is a brain-penetrant, selective, pan-mutant BRAF inhibitor. PF-07799933 inhibited signaling in vitro, disrupted endogenous mutant-BRAF:wild-type-CRAF dimers, and spared wild-type ERK signaling. PF-07799933 ± binimetinib inhibited growth of mouse xenograft tumors driven by mutant BRAF that functions as dimers and by BRAF V600E with acquired resistance to current RAF inhibitors. We treated patients with treatment-refractory BRAF-mutant solid tumors in a first-in-human clinical trial (NCT05355701) that utilized a novel, flexible, pharmacokinetics-informed dose escalation design that allowed rapid achievement of PF-07799933 efficacious concentrations. PF-07799933 ± binimetinib was well-tolerated and resulted in multiple confirmed responses, systemically and in the brain, in BRAF-mutant cancer patients refractory to approved RAF inhibitors.

Manzamine A reduces androgen receptor transcription and synthesis by blocking E2F8-DNA interactions and effectively inhibits prostate tumor growth in mice.

The androgen receptor (AR) is the main driver in the development of castration-resistant prostate cancer, where the emergence of AR splice variants leads to treatment-resistant disease. Through detailed molecular studies of the marine alkaloid manzamine A (MA), we identified transcription factor E2F8 as a previously unknown regulator of AR transcription that prevents AR synthesis in prostate cancer cells. MA significantly inhibited the growth of various prostate cancer cell lines and was highly effective in inhibiting xenograft tumor growth in mice without any pathophysiological perturbations in major organs. MA suppressed the full-length AR (AR-FL), its spliced variant AR-V7, and the AR-regulated prostate-specific antigen (PSA; also known as KLK3) and human kallikrein 2 (hK2; also known as KLK2) genes. RNA sequencing (RNA-seq) analysis and protein modeling studies revealed E2F8 interactions with DNA as a potential novel target of MA, suppressing AR transcription and its synthesis. This novel mechanism of blocking AR biogenesis via E2F8 may provide an opportunity to control therapy-resistant prostate cancer over the currently used AR antagonists designed to target different parts of the AR gene.

Abstract 462: Developing the miR-888 cluster as a therapeutic target for prostate cancer

Abstract Prostate Cancer (PCa) is a serious health crisis in the United States. 20% of men diagnosed with PCa will progress to fast-growing, advanced disease. There are no curative treatment options for PCa that has spread to distant sites and the 5-year survival rate for metastatic disease remains 30%. Recognizing the need for better PCa therapeutics, we are developing novel anti-microRNA delivery reagents targeted against the noncoding RNA miR-888 cluster to block prostate tumor progression. Our lab identified these oncomiRs in a biomarker discovery screen as elevated in human metastatic PCa cell lines and prostatic fluids from patients with high-grade PCa. We noted that over-expression of miR-888 cluster members (miR-888, miR-891a) promoted prostate cell growth and induced invasiveness in vitro. miR-888 and miR-891a also accelerated xenograft tumor growth in mice. Treatment of aggressive PCa cells in culture with synthetic antisense inhibitors against individual cluster members reversed these growth and invasion phenotypes, highlighting their clinical potential. We are testing pH Low Insertion Peptide (pHLIP)-Peptide Nucleic Acid (PNA)-based antimiR conjugates against miR-888 and miR-891a. The delivery vehicle pHLIP is a 36-amino acid peptide that at low pH (< pH 6.5) adopts an alpha-helical conformational change and facilitates the insertion of its C-terminus across lipid bilayers to transport conjugated anti-miRNA cargo into cells. When administered systemically, pHLIP effectively targets solid tumors with acidic microenvironments. We found that these reagents are readily internalized by human PCa cells cultured at pH 6.0 and in prostate xenograft tumors when delivered systemically in mice. Treatment significantly repressed miR-888 and miR-891a and acted to slow prostate cell growth in vitro. We are currently moving these studies into mouse prostate models. Furthermore, we are investigating the downstream signaling pathways for the miR-888 cluster. Our work indicates that the miR-888 cluster network coordinates the repression of the Tissue Inhibitors of Metalloproteinase (TIMP) and SMAD4 anti-metastatic pathways to drive extracellular matrix degradation and prostate cell invasion, and as a consequence, induces matrix metalloproteinase (MMP) activity. Expression profiling arrays and luciferase reporter assays indicated that multiple members of the miR-888 cluster co-suppress TIMPs in the prostate and similarly elevate multiple MMPs as well as cadherins, fibronectin and heparinase, and co-modulated several immune response genes. We are currently studying the consequence of various CRISPR-mediated miR-888 cluster deletions to understand how this non-coding RNA cluster functionally overlaps to promote aggressive PCa. This work will establish new clinical tools for aggressive PCa and optimize patient treatment management. Citation Format: Katherine Routon, Trevor Fachko, Vishal Kasina, Raman Bahal, Aurora Esquela Kerscher. Developing the miR-888 cluster as a therapeutic target for prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 462.

Efficacy and delivery strategies of the dual Rac/Cdc42 inhibitor MBQ-167 in HER2 overexpressing breast cancer

Trastuzumab and trastuzumab-based treatments are the standard of care for breast cancer patients who overexpress the human epidermal growth factor receptor 2 (HER2). However, patients often develop resistance to trastuzumab via signaling from alternative growth factor receptors that converge to activate guanine nucleotide exchange factors (GEFs) that in turn activate the Rho GTPases Rac and Cdc42. Since Rac and Cdc42 have been implicated in high tumor grade and therapy resistance, inhibiting the activity of Rac and Cdc42 is a rational strategy to overcome HER2-targeted therapy resistance. Therefore, our group developed MBQ-167, a dual Rac/Cdc42 inhibitor with IC50s of 103 nM and 78 nM for Rac and Cdc42, respectively, which is highly effective in reducing cell and tumor growth and metastasis in breast cancer cell and mouse models. Herein, we created a trastuzumab resistant variant of the SKBR3 HER2 positive breast cancer cell line and show that Rac activation is a central mechanism in trastuzumab resistance. Next, we tested the potential of targeting MBQ-167 to HER2 overexpressing trastuzumab-resistant cell lines in vitro, and show that MBQ-167, but not trastuzumab, reduces cell viability and induces apoptosis. When MBQ-167 was targeted to mammary fatpad tumors established from HER2 overexpressing cells via immunoliposomes functionalized with trastuzumab, MBQ-167 and MBQ-167-loaded liposomes show equal efficacy in reducing the viability of trastuzumab-resistant cells, inhibiting tumor growth in mouse xenografts, and reducing metastasis to lungs and liver. This study demonstrates the efficacy of MBQ-167 as an alternative therapeutic in HER2 overexpressing cancers, delivered either in free form or in liposomes.

Cafestol inhibits colon cancer cell proliferation and tumor growth in xenograft mice by activating LKB1/AMPK/ULK1-dependent autophagy

Chemotherapy failure in colorectal cancer patients is the major cause of recurrence and poor prognosis. As a result, there is an urgent need to develop drugs that have a good chemotherapy effect while also being extremely safe. In this study, we found cafestol inhibited colon cancer growth and HCT116 proliferation in vivo and in vitro, and improved the composition of intestinal flora. Further metabolomic data showed that autophagy and AMPK pathways were involved in the process of cafestol's anti-colon cancer effects. The functional validation studies revealed that cafestol increased autophagy vesicles and LC3B-II levels. The autophagic flux induced by cafestol was prevented by using BafA1. The autophagy inhibitor 3-MA blocked the cafestol-induced increase in LC3B-II and cell proliferation inhibition. Then we found that cafestol induced the increased expressions of LKB1, AMPK, ULK1, p-LKB1, p-AMPK, and p-ULK1 proteins in vivo and in vitro. Using the siRNA targeted to the Lkb1 gene, the levels of AMPK, ULK1, and LC3B-II were suppressed under cafestol treatment. These results indicated that the effect of cafestol is through regulating LKB1/AMPK/ULK1 pathway-mediated autophagic death. Finally, a correlation matrix of the microbiome and autophagy-related proteins was conducted. We found that cafestol-induced autophagic protein expression was positively correlated with the beneficial intestinal bacteria (Muribaculaceae, Bacteroides, Prevotellacece, and Alloprevotella) and negatively correlated with the hazardous bacteria. Conclusions: This study found that cafestol inhibited colon cancer in vitro and in vivo by the mechanism that may be related to LKB1/AMPK/ULK1 pathway-mediated autophagic cell death and improved intestinal microenvironment.

Flavokawain C inhibits proliferation and migration of liver cancer cells through FAK/PI3K/AKT signaling pathway

PurposeThis study investigated the potential applicability and the underlying mechanisms of flavokawain C, a natural compound derived from kava extracts, in liver cancer treatment.MethodsDrug distribution experiment used to demonstrate the preferential tissues enrichment of flavokawain C. Cell proliferation, apoptosis and migration effect of flavokawain C were determined by MTT, colony formation, EdU staining, cell adhesion, transwell, flow cytometry and western blot assay. The mechanism was explored by comet assay, immunofluorescence assay, RNA-seq-based Kyoto encyclopedia of genes and genomes analysis, molecular dynamics, bioinformatics analysis and western blot assay. The anticancer effect of flavokawain C was further confirmed by xenograft tumor model.ResultsThe studies first demonstrated the preferential enrichment of flavokawain C within liver tissues in vivo. The findings demonstrated that flavokawain C significantly inhibited proliferation and migration of liver cancer cells, induced cellular apoptosis, and triggered intense DNA damage along with strong DNA damage response. The findings from RNA-seq-based KEGG analysis, molecular dynamics, bioinformatics analysis, and western blot assay mechanistically indicated that treatment with flavokawain C notably suppressed the FAK/PI3K/AKT signaling pathway in liver cancer cells. This effect was attributed to the induction of gene changes and the binding of flavokawain C to the ATP sites of FAK and PI3K, resulting in the inhibition of their phosphorylation. Additionally, flavokawain C also displayed the strong capacity to inhibit Huh-7-derived xenograft tumor growth in mice with minimal adverse effects.ConclusionsThese findings identified that flavokawain C is a promising anticancer agent for liver cancer treatment.

STC2 is a potential biomarker of hepatocellular carcinoma with its expression being upregulated in Nrf1α-deficient cells, but downregulated in Nrf2-deficient cells

Nrf1 (encoded by Nfe2l1) and Nrf2 (encoded by Nfe2l2), as two key members of the CNC-bZIP transcription factor, exhibit significant functional differences in their pathophysiology. Our previous findings demonstrated that loss of Nrf1α (i.e., a full-length isoform of Nrf1) promotes HepG2-derived tumor growth in xenograft mice, but malgrowth of the xenograft tumor is significantly suppressed by knockout of Nrf2. To gain insights into the mechanism underlying such marked distinctions in their pathologic phenotypes, we mined transcriptome data from liver cancer in the TCGA database to establish a prognostic model and calculate predicted risk scores for each cell line. The results revealed that knockout of Nrf1α markedly increased the risk score in HepG2 cells, whereas the risk score was reduced by knockout of Nrf2. Notably, stanniocalcin 2 (STC2), a biomarker associated with liver cancer, that is upexpressed in hepatocellular carcinoma (HCC) tissues with a reduction in the overall survival ratio of those patients. We observed increased expression levels of STC2 in Nrf1α−/− cells but decreased expression in Nrf2−/− cells. These findings suggested that STC2 may play a role in mediating the distinction between Nrf1α−/− and Nrf2−/−. Such potential function of STC2 was further corroborated through a series of experiments combined with transcriptomic sequencing. The results revealed that STC2 functions as a dominant tumor-promoter, because the STC2-leading increases in clonogenicity of hepatoma cells and malgrowth of relevant xenograft tumor were almost completely abolished in STC2−/− cells. Together, these demonstrate that STC2 could be paved as a potential therapeutic target, albeit as a diagnostic marker, for HCC.

THU551 Glycoprotein-NMB (GPNMB) Is A Potential Lymphangioleiomyomatosis (LAM) Therapeutic Target And Biomarker

Abstract Disclosure: E. Gibbons: None. S.R. Hammes: None. Lymphangioleiomyomatosis (LAM) is a rare, progressive, destructive cystic lung disease affecting almost exclusively female-sexed individuals. Mutations in the tuberous sclerosis (TSC1 or TSC2) genes constitutively activate the mTORC1 pathway, promoting hyperproliferation of smooth muscle cells, creating small tumors throughout the lungs. These tumors, through largely unknown mechanisms, result in the formation of large cysts that replace normal alveolar space. Inhibition of mTORC1 with Sirolimus slows but does not stop LAM progression; therefore, there is a need for new LAM treatment options and biomarkers. Due to LAM’s estrogen sensitivity, female specificity, and metastatic nature, we previously proposed LAM cells originate from the uterine myometrium. We therefore designed a uterine-specific TSC2-null mouse model where all the mice generate uterine tumors characteristic of LAM and half develop lung metastases, suggesting that indeed LAM tumors may be derived from the uterus. Using bulk RNASeq analysis of uterine tissue from our mouse model, when focusing on genes regulated by estrogen and TSC2, we discovered increased expression of melanocytic markers, including Glycoprotein Non-Metastatic Melanoma Protein B (GPNMB), a known oncogenic protein in other cancers. GPNMB was not only highly expressed in our mouse model; it was also expressed intracellularly and on the cell surface of TSC2-null cell lines and in LAM tumor cells from patient lungs and uteri. Notably, the extracellular domain of GPNMB was released from the surface of TSC2-null cell lines, suggesting that the ectodomain may also be released from TSC2-null cells in LAM patients. Here we show that, GPNMB protein and mRNA expression increased when the cells were serum starved, mimicking conditions of a tumor microenvironment. This increase was dependent on mTORC1 signaling and mRNA transcription. Knocking down GPNMB expression by siRNA had minimal effects on TSC2-null cells pro-tumorigenic functions in vitro aside from decreasing invasion. However, knocking out GPNMB in TSC2-null cells using CRISPR/Cas9 significantly decreased mouse xenograft tumor growth. Additionally, treating mice with a GPNMB antibody drug conjugate abrogated xenograft growth, highlighting GPNMB’s potential as a therapeutic target. Also, GPNMB’s ectodomain was released from the cell surface of TSC2-null cells by the proteases Adam10 and 17. Of note, the ectodomain is implicated in mediating GPNMB’s effects on tumor growth, suggesting that Adam10/17 inhibition may mitigate TSC2-null tumor growth. Importantly, the GPNMB ectodomain is a potential serum biomarker of LAM, as there was a significant increase in GPNMB ectodomain levels in patient serum as compared with healthy controls. Furthermore, serum GPNMB levels decreased in most patients after Sirolimus treatment, implicating GPNMB as a potential marker for responsiveness to treatment. Presentation: Thursday, June 15, 2023

LncRNA RP11-58O9.2 predicts poor prognosis and promotes progression of non-small cell lung cancer.

Long non-coding RNAs (lncRNAs) play a crucial role in non-small cell lung cancer (NSCLC). This study aimed to investigate the novel biomarker, lncRNA RP11-58O9.2, in patients with NSCLC. RP11-58O9.2 expression in NSCLC cells and tissues was detected by reverse transcription-quantitative polymerase chain reaction. Patient survival was analyzed in relation to RP11-58O9.2 expression levels. RP11-58O9.2 expression was knocked down and endogenous expression was verified in two NSCLC cell lines. Cell proliferation was then assessed by Cell Counting Kit-8 and colony-formation assays, and cell invasion and migration were assessed by Transwell and wound-healing assays, respectively. In vivo experiments were performed in mice, and the combination of RP11-58O9.2 and miR-6749-3p was predicted by miRanda. RP11-58O9.2 was highly expressed in NSCLC cell lines and tissues, and was associated with advanced stage, lymphatic metastasis, and differentiation group. High RP11-58O9.2 levels were also associated with shorter survival. RP11-58O9.2 knockdown inhibited the proliferation, invasion, and migration of lung cancer cells, and tumor growth in mouse xenografts in vivo. RP11-58O9.2 may target and regulate miR-6749-3p. LncRNA RP11-58O9.2 is associated with NSCLC prognosis and promotes lung cancer progression. Further studies are needed to investigate the mechanisms and the regulatory association between RP11-58O9.2 and miR-6749-3p.

FOXP2 suppresses the proliferation, invasion, and aerobic glycolysis of hepatocellular carcinoma cells by regulating the KDM5A/FBP1 axis.

The Warburg effect is the preference of cancer cells to use glycolysis rather than oxidative phosphorylation to generate energy. Accumulating evidence suggests that aerobic glycolysis is widespread in hepatocellular carcinoma (HCC) and closely related to tumorigenesis. The purpose of this study was to investigate the role and mechanism of forkhead box P2 (FOXP2) in aerobic glycolysis and tumorigenesis in HCC. Here, we found that FOXP2 was lower expressed in HCC tissues and cells than in nontumor tissues and normal hepatocytes. Overexpression of FOXP2 suppressed cell proliferation and invasion of HCC cells and promoted cell apoptosis in vitro, and hindered the growth of mouse xenograft tumors in vivo. Further researches showed that FOXP2 inhibited the Warburg effect in HCC cells. Moreover, we demonstrated that FOXP2 up-regulated the expression of fructose-1, 6-diphosphatase (FBP1), and the inhibitory effect of FOXP2 on glycolysis was dependent on FBP1. Mechanistically, as a transcription factor, FOXP2 negatively regulated the transcription of lysine-specific demethylase 5A (KDM5A), and then blocked KDM5A-induced H3K4me3 demethylation in FBP1 promoter region, thereby promoting the expression of FBP1. Consistently, overexpressing KDM5A or silencing FBP1 effectively reversed the inhibitory effect of FOXP2 on HCC progression. Together, our findings revealed the mechanistic role of the FOXP2/KDM5A/FBP1 axis in glycolysis and malignant progression of HCC cells, providing a potential molecular target for the therapy of HCC.

Auranofin inhibits the occurrence of colorectal cancer by promoting mTOR-dependent autophagy and inhibiting epithelial-mesenchymal transformation.

Colorectal cancer (CRC) is one of the world's most common and deadly cancers. According to GLOBOCAN2020's global incidence rate and mortality estimates, CRC is the third main cause of cancer and the second leading cause of cancer-related deaths worldwide. The US Food and Drug Administration has approved auranofin for the treatment of rheumatoid arthritis. It is a gold-containing chemical that inhibits thioredoxin reductase. Auranofin has a number of biological activities, including anticancer activity, although it has not been researched extensively in CRC, and the mechanism of action on CRC cells is still unknown. The goal of this research was to see how Auranofin affected CRC cells in vivo and in vitro . The two chemical libraries were tested for drugs that make CRC cells more responsive. The CCK-8 technique was used to determine the cell survival rate. The invasion, migration, and proliferation of cells were assessed using a transwell test and a colony cloning experiment. An electron microscope was used to observe autophagosome formation. Western blotting was also used to determine the degree of expression of related proteins in cells. Auranofin's tumor-suppressing properties were further tested in a xenograft tumor model of human SW620 CRC cells. Auranofin dramatically reduced the occurrence of CRC by decreasing the proliferation, migration, and invasion of CRC cells, according to our findings. Through a mTOR-dependent mechanism, auranofin inhibits the epithelial-mesenchymal transition (EMT) and induces autophagy in CRC cells. Finally, in-vivo tests revealed that auranofin suppressed tumor growth in xenograft mice while causing no harm. In summary, auranofin suppresses CRC cell growth, invasion, and migration. Auranofin inhibits the occurrence and progression of CRC by decreasing EMT and inducing autophagy in CRC cells via a mTOR-dependent mechanism. These findings suggest that auranofin could be a potential chemotherapeutic medication for the treatment of human CRC.

Exosome-Mediated Activation of the Prostasin-Matriptase Serine Protease Cascade in B Lymphoma Cells.

Prostasin and matriptase are extracellular membrane serine proteases with opposing effects in solid epithelial tumors. Matriptase is an oncoprotein that promotes tumor initiation and progression, and prostasin is a tumor suppressor that reduces tumor invasion and metastasis. Previous studies have shown that a subgroup of Burkitt lymphoma have high levels of ectopic matriptase expression but no prostasin. Reducing the matriptase level via small interfering RNAs in B lymphoma cells impeded tumor xenograft growth in mice. Here, we report a novel approach to matriptase regulation in B cancer cells by prostasin via exosomes to initiate a prostasin-matriptase protease activation cascade. The activation and shedding of matriptase were monitored by measuring its quantity and trypsin-like serine protease activity in conditioned media. Sustained activation of the protease cascade in the cells was achieved by the stable expression of prostasin. The B cancer cells with prostasin expression presented phenotypes consistent with its tumor suppressor role, such as reduced growth and increased apoptosis. Prostasin exosomes could be developed as an agent to initiate the prostasin-matriptase cascade for treating B lymphoma with further studies in animal models.

Endometrium-derived mesenchymal stem cells suppress progression of endometrial cancer via the DKK1-Wnt/β-catenin signaling pathway

BackgroundMesenchymal stem cell (MSC) therapy is an attractive treatment option for various cancers. Whether MSCs can be used to treat well-differentiated endometrial cancer (EC) remains unclear. The aim of this study is to explore the potential therapeutic effects of MSCs on EC and the underlying mechanisms.MethodsThe effects of adipose-derived MSCs (AD-MSCs), umbilical-cord-derived MSCs (UC-MSCs), and endometrium-derived MSCs (eMSCs) on the malignant behaviors of EC cells were explored via in vitro and in vivo experiments. Three EC models, including patient-derived EC organoid lines, EC cell lines, and EC xenograft model in female BALB/C nude mice, were used for this study. The effects of MSCs on EC cell proliferation, apoptosis, migration, and the growth of xenograft tumors were evaluated. The potential mechanisms by which eMSCs inhibit EC cell proliferation and stemness were explored by regulating DKK1 expression in eMSCs or Wnt signaling in EC cells.ResultsOur results showed that eMSCs had the highest inhibitory effect on EC cell viability, and EC xenograft tumor growth in mice compared to AD-MSCs and UC-MSCs. Conditioned medium (CM) obtained from eMSCs significantly suppressed the sphere-forming ability and stemness-related gene expression of EC cells. In comparison to AD-MSCs and UC-MSCs, eMSCs had the highest level of Dickkopf-related protein 1 (DKK1) secretion. Mechanistically, eMSCs inhibited Wnt/β-catenin signaling in EC cells via secretion of DKK1, and eMSCs suppressed EC cell viability and stemness through DKK1-Wnt/β-catenin signaling. Additionally, the combination of eMSCs and medroxyprogesterone acetate (MPA) significantly inhibited the viability of EC organoids and EC cells compared with eMSCs or MPA alone.ConclusionsThe eMSCs, but not AD-MSCs or UC-MSCs, could suppress the malignant behaviors of EC both in vivo and in vitro via inhibiting the Wnt/β-catenin signaling pathway by secreting DKK1. The combination of eMSCs and MPA effectively inhibited EC growth, indicating that eMSCs may potentially be a new therapeutic strategy for young EC patients desiring for fertility preservation.

Circ_0003356 suppresses gastric cancer growth through targeting the miR-668-3p/SOCS3 axis.

Circular RNAs (circRNAs) have attracted extensive attention as therapeutic targets in gastric cancer (GC). Circ_0003356 is known to be downregulated in GC tissues, but its cellular function and mechanisms remain undefined. To investigate the role of circ_0003356 in GC at the molecular and cellular level. Circ_0003356, miR-668-3p, and SOCS3 expression were assessed via quantitative real time-polymerase chain reaction (qRT-PCR). Wound healing, EdU, CCK-8, flow cytometry and transwell assays were used to analyze the migration, proliferation, viability, apoptosis and invasion of GC cells. The subcellular localization of circ_0003356 was monitored using fluorescence in situ hybridization. The interaction of circ_0003356 with miR-668-3p was confirmed using RIP-qRT-PCR, RNA pull-down, and dual luciferase reporter assays. We observed protein levels of genes via western blot. We injected AGS cells into the upper back of mice and performed immunohistochemistry staining for examining E-cadherin, N-cadherin, Ki67, and SOCS3 expressions. TUNEL staining was performed for the assessment of apoptosis in mouse tumor tissues. Circ_0003356 and SOCS3 expression was downregulated in GC cells, whilst miR-668-3p was upregulated. Exogenous circ_0003356 expression and miR-668-3p silencing suppressed the migration, viability, proliferation, epithelial to mesenchy-mal transition (EMT) and invasion of GC cells and enhanced apoptosis. Circ_0003356 overexpression impaired tumor growth in xenograft mice. Targeting of miR-668-3p by circ_0003356 was confirmed through binding assays and SOCS3 was identified as a downstream target of miR-668-3p. The impacts of circ_0003356 on cell proliferation, apoptosis, migration, invasion and EMT were reversed by miR-668-3p up-regulation or SOCS3 down-regulation in GC cells. Circ_0003356 impaired GC development through its interaction with the miR-668-3p/SOCS3 axis.

SCARA5 in bone marrow stromal cell-derived exosomes inhibits colorectal cancer progression by inactivating the PI3K/Akt pathway

Colorectal cancer (CRC) is the fourth most frequently diagnosed cancer worldwide. Bone marrow stromal cells (BMSCs) play an essential role in tumor development by secreting exosomes. Scavenger receptor class A member 5 (SCARA5) is a newly identified tumor suppressor. This study aimed to investigate the effects of BMSCs-derived exosomes (BMSCs-Exos) on CRC development and to explore their regulatory mechanisms. BMSCs-Exos showed an oval-shaped, bilayer membrane structure. BMSCs-Exos inhibited growth and motility of CRC cells, while BMSCs-Exos with SCARA5 knockdown significantly promoted cell proliferation and movement. Exosomal SCARA5 also effectively suppressed colorectal tumor growth in mouse xenografts. Further analysis revealed that exosomal SCARA5 inhibited the phosphorylation of protein kinase B and phosphoinositide 3-kinase in both CRC cells and tumors. In conclusion, SCARA5 in BMSCs-Exos inhibited CRC progression by inactivating PI3K/Akt, thus suggesting the potential clinical application of SCARA5-containing BMSCs-Exos for CRC treatment.

Extracellular vesicular lncRNA FAL1 promotes hepatocellular carcinoma cell proliferation and invasion by inducing macrophage M2 polarization.

Current evidence finds that circulating exosomal lncRNA focally amplified lncRNA on chromosome 1 (FAL1) promotes the progression of hepatocellular carcinoma (HCC). However, the underlying mechanism of serum extracellular vesicular FAL1 in HCC progression remains elusive. Here, we extracted extracellular vesicles (EVs) from serum samples of HCC patients and healthy volunteers, and found that FAL1 was highly enriched in the serum EVs of HCC patients. Then, macrophages were treated with EVs alone or together with small interfering RNA against FAL1 (si-FAL1). The data indicated that FAL1-enriched EVs induced macrophage M2 polarization, while silencing FAL1 in macrophages antagonized the role of EVs. Moreover, HepG2 cells were co-cultured with the conditioned macrophages, and co-culturing with EVs-incubated macrophages promoted HepG2 cell proliferation, invasion, cell cycle progression, and colony formation, and inhibited cell apoptosis and sorafenib sensitivity, while interfering FAL1 in macrophages reversed these effects. Consistently, ectopic expression of FAL1 in macrophages also induced macrophage M2 polarization, and co-culture of FAL1-overexpressing macrophages with HepG2 cells facilitated the malignant progression of HepG2 cells. Furthermore, co-culturing HepG2 cells with EVs-incubated macrophages activated the Wnt/β-catenin signaling pathway, and treatment with a Wnt/β-catenin pathway inhibitor IWP-2 partially neutralized the effect of EVs-incubated macrophages on HepG2 cell malignant behaviors. Additionally, FAL1 enriched EVs-incubated macrophages markedly increased mouse xenograft tumor growth. In conclusion, extracellular vesicular lncRNA FAL1 promotes macrophage M2 polarization and further activates the Wnt/β-catenin signaling pathway in HCC cells, thus promoting HCC progression.

Abstract 2600: BBOX1 is a novel tumor suppressor in kidney cancer

Abstract Renal cell carcinoma (RCC) is a common type of cancer with a steady increase in new cases and deaths for the past several decades while its development is not fully understood. We previously identified the γ-butyrobetaine hydroxylase 1 (BBOX1), a member of the 2-oxoglutarate dependent dioxygenase family whereas functionally uncharacterized previously in human cancers, plays a vital oncogenic role in triple-negative breast cancer. However, the role of BBOX1 in other cancers such as kidney cancer remains unclear. We found that BBOX1 is a highly context-dependent enzyme, reflected by its expression only detected in a few organs such as kidney. Intriguingly, according to our immunohistochemistry staining results and the data from The Human Protein Atlas database, BBOX1 is only expressed in the proximal tubule cells where clear cell RCC (ccRCC, the most common form of kidney cancer) derives from, indicating a connection of BBOX1 with kidney malignant transformation. In this study, we investigated the BBOX1 mRNA and protein expression in paired normal and tumor ccRCC patient samples from the UTSW Kidney Cancer Specialized Program of Research Excellence (SPORE) program, as well as patient data from The Cancer Genome Atlas (TCGA) or Clinical Proteomic Tumor Analysis Consortium (CPTAC), which consistently showed that BBOX1 is remarkably downregulated in the ccRCC patient tumors compared to normal kidneys, and its low expression associates with worse prognosis in ccRCC patients. Furthermore, expression of BBOX1 was highly presented in the human primary renal proximal tubule epithelial cells (RPTEC) while robustly suppressed after malignant transformation of the RPTEC cells. These data suggest a pathological loss of BBOX1 during RCC progression. Restoration of BBOX1 in multiple human ccRCC cell lines suppressed xenograft tumor growth in mice but not in the 2D in vitro growth with normal tissue culture conditions, suggesting BBOX1 plays an important role in ccRCC tumor development. By comparing the gene expression profiles from transcriptomics analyses in the control or BBOX1 overexpression samples either from xenograft tumors or cells grown in normal 2D culture, we found that BBOX1 suppresses the mTORC1 signaling only in the in vivo condition. Interestingly, we could recapitulate this phenomenon by culturing the control or BBOX1 overexpression ccRCC cells in a physiologic medium but not the standard cell culture medium. These data suggested BBOX1 may regulate the mTORC1 signaling depending on the nutrient status of the tumor cells. Overall, we identified BBOX1 as a novel tumor suppressor in ccRCC. Citation Format: Chengheng Liao, Liwei Jia, Hua Zhong, Lianxin Hu, Payal Kapur, James Brugarolas, Qing Zhang. BBOX1 is a novel tumor suppressor in kidney cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2600.

Abstract 2531: FCN-683, a novel second-generation BCL-2 inhibitor, is highly potent, selective and efficacious against clinically relevant venetoclax-resistant mutations

Abstract B-cell lymphoma 2 (BCL-2) is a member of the anti-apoptotic BCL-2 family and is dysregulated in B-cell malignancies, including chronic lymphocytic leukemia (CLL)/small lymphocytic lymphoma (SLL), acute myeloid leukemia (AML) and Non-Hodgkin’s lymphoma. Venetoclax (VEN), also known as ABT-199, is the only BCL-2 inhibitor approved by FDA for treating CLL/SLL and AML. VEN is a BH3-mimetic drug competitively inhibits BCL-2 by binding to the hydrophobic groove and thereby displacing proapoptotic proteins and inducing apoptosis. Despite high effectiveness of the initial treatment, most patients treated with VEN eventually relapse or develop resistance. An important resistance mechanism is acquisition of BCL-2 G101V mutation, detected in about 50% of CLL patients 19-42 months after receiving VEN. Other resistance mutations identified clinically so far include D103, A113G, R129L, and V156D, etc. Overcoming VEN-resistant Bcl-2 mutations represent an unmet medical need. Here, we introduce a novel and selective second-generation oral BCL-2 inhibitor, FCN-683, with sub-nano or single nanomolar affinity to BCL-2 and VEN-resistant BCL-2 mutations including G101V, D103E/V/Y, F104L, A113G, R129L and V156D. FCN-683 showed much higher affinity to BCL-2 than BCL-xL, suggesting its good potential to avoid BCL-xL-linked thrombocytopenia. FCN-683 exhibited comparable or superior anti-proliferation activities compared with VEN in various BCL-2-addicted human B-cell lymphoma cells, including DOHH2 follicular lymphoma cells, Toledo diffuse large B-cell lymphoma cells, and RS4;11 acute lymphoblastic leukemia cells, while sparing BCL-xL-dependent cells. Of note, FCN-683 displayed potent anti-proliferative activities against a panel of genetically engineered RS4;11 cells ectopically expressing VEN-resistant BCL-2 mutants such as G101V, D103 or several other mutants above-mentioned, outperforming VEN. Correspondingly, FCN-683 significantly inhibited tumor growth in mice xenografts derived from human B-cell lymphomas harboring BCL-2 or various VEN-resistant BCL-2 mutations and its anti-tumor efficacy was much superior to VEN. In non-clinical studies, FCN-683 possessed excellent pharmacokinetic (PK) properties comparable to VEN. Preferable safety profiles of FCN-683 were shown with no potential hERG inhibitory effect and less drug-drug interaction potential, as evidenced by no inhibitory effect (IC50 >50 μM) on CYP2C9 enzyme compared with VEN (IC50 1.05 μM). Together, FCN-683 is highly potent, selective and highly efficacious against a variety of clinically relevant VEN-resistance BCL-2 mutations in vitro and in vivo and exhibits favorable PK and safety profiles, highlighting its therapeutic potential to become an effective therapeutic approach for VEN-naïve or -resistant BCL-2-addicted B-cell malignancies. Citation Format: Shu (Sophie) Lin, Hongbin Liu, Rui Tan, Weipeng Zhang, Chengxi He, Yue Rong, Zhuo Huang, Jinhua Yu, Yunling Wang, Yangli Qi, Xingdong Zhao, Lihua Jiang, Yanxin Liu, Xilei Wang, Zongyao Zou, Jing Sun, Yuwei Gao, Weibo Wang, Xiaohui Guan, Yifang Wu. FCN-683, a novel second-generation BCL-2 inhibitor, is highly potent, selective and efficacious against clinically relevant venetoclax-resistant mutations [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2531.

PM2.5 promotes lung cancer progression through activation of the AhR-TMPRSS2-IL18 pathway.

Particulate matter 2.5 (PM2.5) is a risk factor for lung cancer. In this study, we investigated the molecular mechanisms of PM2.5 exposure on lung cancer progression. We found that short-term exposure to PM2.5 for 24 h activated the EGFR pathway in lung cancer cells (EGFR wild-type and mutant), while long-term exposure of lung cancer cells to PM2.5 for 90 days persistently promoted EGFR activation, cell proliferation, anchorage-independent growth, and tumor growth in a xenograft mouse model in EGFR-driven H1975 cancer cells. We showed that PM2.5 activated AhR to translocate into the nucleus and promoted EGFR activation. AhR further interacted with the promoter of TMPRSS2, thereby upregulating TMPRSS2 and IL18 expression to promote cancer progression. Depletion of TMPRSS2 in lung cancer cells suppressed anchorage-independent growth and xenograft tumor growth in mice. The expression levels of TMPRSS2 were found to correlate with nuclear AhR expression and with cancer stage in lung cancer patient tissue. Long-term exposure to PM2.5 could promote tumor progression in lung cancer through activation of EGFR and AhR to enhance the TMPRSS2-IL18 pathway.