Abstract Background: Prostate cancer (PCa) is the second most frequently diagnosed malignancy among men. While multiple protein markers have been implicated in PCa, findings from conventional studies are often inconsistent due to methodological limitations such as selection bias and uncontrolled confounding. The proteome-wide association study (PWAS) design leverages genetic instruments to identify protein biomarkers with potential causal roles in diseases. Although candidate causal proteins in blood have been identified for PCa in our previous work, few studies have focused on prostate tissue. Methods: We conducted the first prostate tissue-based PWAS using data from the PRACTICAL/ELLIPSE consortia, comprising 122,188 PCa cases and 604,640 controls. Proteomic and genomic data were generated from 201 frozen prostate tissue samples without PCa, quantifying 11,575 proteins. We used data of 195 unrelated subjects for model building. Prediction models for protein abundance were built using nearby unambiguous SNPs of potentially associated variants, applying BLUP, LASSO, elastic net, and top1 methods. Association testing was performed for genetically predicted protein levels with PCa risk and aggressiveness. For one of the identified proteins eIF4G1, we performed knockdown of its gene expression in androgen-sensitive (LNCaP), enzalutamide-resistant LNCaP (NO-LNCaP-ENZR), and castration-resistant (22RV1) PCa cell lines, and investigated the effects on multiple phenotypes. Survival analysis was also performed using TCGA primary PCa RNA-seq data. Results: A total of 1,034 protein models achieved cross-validated R2 > 0.01 and were retained for association testing. Fifty-six proteins showed significant associations with PCa risk, including 18 associated with advanced disease and seven distinguishing advanced from non-advanced cases. One of the top novel proteins, EIF4G1, is required for the initial steps of translation. Disrupting eIF4F complex activity via EIF4G1 knockdown reduced cell proliferation, colony formation, and spheroid culture growth, and decreased cell migration and invasion. EIF4G1 knockdown also sensitized LNCaP cells to enzalutamide treatment and inhibited clonogenic potential of enzalutamide-resistant cells. Pharmacological inhibition of eIF4F with SBI-756 reproduced these effects and induced G1 phase cell cycle arrest. Polysome profiling revealed decreased mRNA loading onto polysomes, indicating that knockdown of EIF4G1 impaired cap-dependent translation. Elevated expression of EIF4G1 in tumors was also associated with shorter disease-specific survival. Conclusions: Our study reveals novel prostate tissue proteins putatively causally linked to PCa risk and aggressiveness. Our functional work suggests that a novel protein, eIF4G1, presents a new target for limiting PCa progression and overcoming therapy resistance. Citation Format: Jingjing Zhu, Pramod KC, Sweaty Koul, Yijun Tian, Hua Zhong, Thomas G. Beach, Hyeyoon Kim, Athena A. Schepmoes, Karl K. Weitz, Tyler Sagendorf, Tao Liu, Maarit I. Tiirikainen, Lucio Miele, Nicholas Mancuso, Timothy R. Rebbeck, David V. Conti, Christopher A. Haiman, the PRACTICAL/ELLIPSE consortium, Chong Wu, Liang Wang, Hari K. Koul, Lang Wu. Uncovering causal protein markers in prostate tissue for prostate cancer: A proteome-wide association study and functional validation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 6322.

Abstract Background: The Hippo-YAP/TAZ-TEAD signaling axis is frequently upregulated in many cancers, including subsets of prostate cancer (PCa). However, its role in therapy resistance remains incompletely understood. In this study, we investigated the therapeutic potential of targeting YAP/TAZ-TEAD signaling in PCa, with an emphasis on androgen-independent and enzalutamide-resistant disease. Methods: LNCaP, PC3, and DU145 cells were obtained from ATCC. Enzalutamide-resistant lines (LNCaP-ENZR/PCaNO1 and C4-2-ENZR/PCaNO2) were generated by culturing LNCaP and C4-2 cells with 5 µM enzalutamide for >6 months. mRNA expression was quantified by qRT-PCR, and protein levels were examined by western blotting. Anti-tumor effects of YAP/TAZ-TEAD inhibitors (GNE-7883, K-975) were assessed using IncuCyte live-cell imaging for proliferation; long-term survival was measured by colony formation assays. Cell migration and invasion were evaluated using scratch-wound healing and Matrigel transwell assays, respectively. Results: Androgen-independent PCa cells (PC3 and DU145) exhibited marked upregulation of YAP/TAZ-TEAD transcriptional targets compared to LNCaP cells. Enzalutamide-resistant PCaNO1 and PCaNO2 cells displayed strong induction of YAP/TAZ-TEAD target genes and increased YAP1, TAZ, and TEAD protein levels relative to parental controls. Enzalutamide resistance was also associated with elevated PD-L1 expression. Pharmacologic inhibition of YAP/TAZ-TEAD signaling significantly suppressed cell growth and proliferation, and reduced colony formation, migration, and invasion across PCa models. Ongoing experiments are assessing the impact of YAP/TAZ-TEAD inhibition on PD-L1 regulation. Conclusion: YAP/TAZ-TEAD inhibitors effectively block proliferation and invasiveness of prostate cancer cells, including enzalutamide-resistant models. These findings support YAP/TAZ-TEAD signaling as a promising therapeutic vulnerability and potential strategy to overcome therapy resistance in subsets of advanced prostate cancer. Citation Format: Vandana Mohan, Sweaty Koul, Mousa Vatanmakanian, Santosh Lamichhane, Praveen K. Jaiswal, Hari K. Koul. Exploring the therapeutic vulnerability of castration-resistant prostate cancer via Hippo-YAP/TAZ-TEAD signaling [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 574.

Prostate cancer results in over 35,000 deaths in USA, annually. Enzalutamide (ENZ) treatment enhances overall patient survival. The development of ENZ-R is marked by adaptive cellular mechanisms, including cellular plasticity and the emergence of CRPC-NEPC and CRPC-DNPC phenotypes. The role of epigenetic mechanisms in CRPC remains less understood. Recent studies, including those from our laboratory, have pointed to increased expression and activity of DNA methyltransferases (DNMTs) and the PRC2 component EZH2 during prostate cancer progression. However, the direct role of DNMTs in ENZ-R has not been thoroughly evaluated. In this study, we explored the potential of DNMT inhibitors and EZH2 inhibitors to sensitize prostate cancer cells to enzalutamide. Enzalutamide-resistant (LNCaP-ENZ-R) cells were developed by maintaining the cells in a medium containing 5 μM ENZ for a minimum of six months, while Short-term treatment with ENZ was conducted for 72h. Where indicated DNMTi (5-AZA-dC) and EZH2i (GSK-126 ) and Enz were used at 5uM concentrations. Proliferation was assessed using Incucyte. Colony formation and cell migration were assessed. Protein and mRNA level were determined by western blot and RT-PCR techniques. We observed that treatment of PCa cells with ENZ increased levels of DNMTs in both short-term (treatment of the LNCaP cells for 72 h) and established ENZ resistant (LNCaP-ENZ-R) cells. We also observed a gradual transformation from epithelial morphology to neuroendocrine phenotype in ENZ-R cells, characterized by spindle-shaped and elongated structures in LNCaP-ENZ-R cells. Moreover, in ENZ-R cells AR levels did not change but AR target (PDEF, PSA, and KRT18) were significantly downregulated, while markers associated with EMT (Snail) and NEPC (CHGA and enolase) were upregulated. Treatment of the cells with a DNMT inhibitor (5-AZA-dC) resulted in a decrease in DNMT levels in both ENZ-sensitive and -resistant cells. EZH2 expression showed no notable changes in either ENZ-sensitive or -resistant cells, however, H3K27me3 levels were increased with ENZ treatment. Additionally, LNCaP cells were sensitive to DNMTs and EZH2 inhibitors, and inhibiting both DNMTs and EZH2 substantially inhibited the growth and proliferation ENZ-sensitive as well as of ENZ-R-PCa cells. We also observed that treatment with inhibitors of DNMT and EZH2 decreased the scratch wound closure and clonogenic activity of PCa cells. Overall, our findings reveal that the DNA and histone methylation pathways play an important role in prostate cancer and development of ENZ-Resistance, and that targeting these epigenetic regulators by small molecule inhibitors, may help overcome therapy resistance in PCa. Supported in part by: Funds from VA Merit Award: I01BX005351, NIH/NCI RO1: CA242839, and LSUHSC, NOLA. Santosh Lamichhane, Brandon E. Burow, Sweaty Koul, Hari K. Koul. Epigenetic drivers of enzalutamide resistance in prostate cancer: targeting of DNMTs and EZH2 as therapeutic strategies to overcome enzalutamide resistance in prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 2756.

Abstract Introduction: The prostate cancer (PCa) microenvironment plays a pivotal role in modulating immune responses, potentially impacting disease progression and treatment outcomes. SPDEF, a transcription factor, has been implicated in PCa progression, yet its influence on the tumor immune microenvironment remains incompletely understood. Methods: To comprehensively evaluate the impact of SPDEF-mediated changes in the PCa microenvironment on immune cells, we employed multiple experimental approaches. Firstly, utilizing the ProcartaPlex Human Cytokine & Chemokine Panel 1 16plex assay, we analyzed cytokine and chemokine alterations in cell culture supernatants from various PCa cell line models—PC3-VC, PC3-SPDEF, RC77/T-VC, RC77/T-SPDEF, LNCaP-VC, and LNCaP-shSPDEF. Subsequently, human primary T cells were exposed to PCa cell-derived conditioned media to assess their proliferation and activation status, using IncuCyte cell imaging and flow cytometry, respectively. Results: Our ProcartaPlex assay validated transcriptomic observations from RNA-seq experiment, confirming elevated cytokine/chemokine levels in SPDEF-overexpressing models and decreased levels in SPDEF-suppressed conditions. Notably, T cell proliferation assays demonstrated increased proliferation in response to SPDEF-overexpressing PCa conditional media and diminished proliferation in SPDEF-suppressed conditions. Moreover, SPDEF downregulation led to decreased proliferation in both CD4+ and CD8+ T cells. Assessing CD8+ T cell activation markers revealed varying impacts on IFN-γ expression, showing reduced levels in LNCaP-shSPDEF but inconclusive effects in PC3-SPDEF overexpression models. Conclusions: These findings highlight the complex interplay between SPDEF alterations in the PCa microenvironment and immune cell behavior, particularly T cell proliferation and activation. The observed effects underscore the complexity of SPDEF-mediated alterations on immune responses within the tumor milieu. Further investigations into the divergent effects of SPDEF on T cell dynamics are warranted to elucidate the precise mechanisms governing these interactions, potentially offering insights into novel therapeutic targets for PCa. Citation Format: Mousa K. Vatanmakanian, Maria Sanchez-Pino, Guanyi K. Zhang, Sweaty Koul, Ramesh T. Puttalingaiah, Mathew Dean, Dorota K. Wyczechowska, Augusto Ochoa, Hari K Koul. Modulation of Prostate Cancer Microenvironment and Immune Responses by SPDEF [abstract]. In: Proceedings of the 17th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2024 Sep 21-24; Los Angeles, CA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2024;33(9 Suppl):Abstract nr C118.

During the last five decades, there has been tremendous development in our understanding of cancer biology and the development of new and novel therapeutics to target cancer. However, despite these advances, cancer remains the second leading cause of death across the globe. Most cancer deaths are attributed to the development of resistance to current therapies. There is an urgent and unmet need to address cancer therapy resistance. Tetrandrine, a bis-benzyl iso-quinoline, has shown a promising role as an anti-cancer agent. Recent work from our laboratory and others suggests that tetrandrine and its derivatives could be an excellent adjuvant to the current arsenal of anti-cancer drugs. Herein, we provide an overview of resistance mechanisms to current therapeutics and review the existing literature on the anti-cancer effects of tetrandrine and its potential use for overcoming therapy resistance in cancer.

Background: The Hippo TEAD-transcriptional regulators YAP1 and TAZ play essential role in cancer cell growth and metastasis. However, the function of YAP1 and TAZ in prostate cancer is not well characterized. We discovered that expression of PDEF is decreased during prostate cancer progression and re-expression of PDEF limits prostate cancer metastasis in part by promoting luminal epithelial phenotype, but mechanisms of PDEF action are not completely understood. In the present study, we evaluated the effects of the SPDEF on YAP1/TAZ levels and expression of YAP1/TAZ regulated genes in prostate cancer (PCa) cells. We also evaluated expression of SPDEF, YAP1, TAZ and YAPTAZZ-Tead regulated genes in clinical cohorts of prostate cancer patients. Material & Method: Prostate cancer (PC3 and DU145) cells were transfected with PDEF or respective vector control. shRNA was used to knock down SPDEF in AR positive and androgen responsive LNCaP cells. Protein levels were analyzed by western blotting. Gene expression was monitored by microarray analysis/RNA seq and confirmed by RTPCR assays. Cell migration and invasion were measured by scratch wound healing and by trans well migration though Matrigel assays respectively. We analyzed publicly available gene expression data in several prostate cancer cohorts. Results: We observed that the two well-characterized metastatic PCa cells (PC3 and DU145 cells) express both YAP1 and TAZ, but do not express SPDEF. Expression of PDEF in PC3 and DU145 cells resulted in an increased phospho-YAP1 and phospho-TAZ protein levels and inhibition of YAP1/TAZ target genes, as compared to the respective vector control, directly demonstrating that PDEF plays a critical role in modulating YAP1/TAZ-TEAD transcriptional activity, and by extension in the regulation of the Hippo pathway. Analysis of publicly available PCa data sets revealed a significant increase in TAZ mRNA levels in prostate cancer tissues as compared to normal prostate tissues (p=4.95E-08). Furthermore, we also found a significant gradual increase in TAZ mRNA expression and concomitant decrease in YAP1 mRNA during disease progression and metastasis and in neuroendocrine PCa. Conclusions: Taken together these data suggest that SPDEF limits prostate cancer metastasis in part by targeting YAP1/TAZ driven transcriptional output. Citation Format: Hari K. Koul, Praveen K. Jaiswal, Suman Mohajan, Mousa Vatanmakanian, Fengtian Wang, Sweaty Koul. PDEF restricts prostate cancer cellular plasticity in part by modulating YAP1/TAZ-TEAD transcriptional network [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 1457.

Background: Prostate cancer (PCa) in African American (AA) men has an earlier onset, more aggressiveness with higher metastasis and mortality rate than in Caucasian men. SAM-pointed domain-containing Ets-like factor (SPDEF) has been identified as a possible suppressor of metastasis in castration-resistant prostate cancer (CRPC) in earlier investigations. Ongoing studies in our lab are focused on deciphering the role of SPDEF in PCa progression and metastasis with special emphasis on PCa in AA men. We discovered that SPDEF expression is lost in RCC7/T cells, and re-expression of SPDEF limits metastatic properties of these cells, however, the regulatory mechanisms underlying the loss of SPDEF have not been elucidated. In the current study, we investigated the role of epigenetic modulators (DNA methylation and histone modifications) in driving the loss of SPDEF. Methods: We analyzed publicly available data sets from TCGA (GDC TCGA Prostate Cancer, and TCGA Prostate Cancer (PRAD) for DNA methylation using Xena UCSC genome browser (https://xena.ucsc.edu/). We also analyzed histone ChIP-seq data from PCa cell lines using cistrome project (http://cistrome.org/db/#/). RCC7/T cells were grown in DMEM and maintained at 37°C in a humidified incubator. We used bisulfite sequencing (BSP) to examine DNA methylation in SPDEF gene in SPDEF proficient (LNCaP) and deficient (RCC7/T) cells. We also employed the ChIP-qPCR to reveal the active and repressive key histone marks (H3K4me3, H3K27ac, and H3K27me3) across the SPDEF gene. Results: In the clinical cohorts, SPDEF expression showed an inverse correlation with the degree of DNA methylation and expression of the epigenetic writer enzymes such as DNMT1 and EZH2. Our results revealed that the CpG islands in SPDEF gene are hyper-methylated in RCC7/T cells compared to LNCaP cells. Our analysis of the data from the cistrome project revealed an elevated enhancer repressive mark H3K27me3 (marked by EZH2) and a decreased promoter active mark, H3K4me3, in PC3 cells as compared with less metastatic LNCaP cells. Our results from ChIP-qPCR confirmed these findings. Moreover, we observed the methylation profiles in RCC7/T cells were similar to those of PC3 cells. Additionally, combination treatment with 5-aza-2-deoxycytidine (DNMT inhibitor) and GSK-126 (EZH2 inhibitor) increased the PDEF expressions levels and also restricted colony formation, migration and invasion in RCC7/T cells. Conclusion: Overall, these findings reveal an inverse correlation between expression of epigenetic writers (DNMT1 and EZH2) and SPDEF expression in PCa. Our results also suggest that SPDEF expression in PCa is regulated in part by epigenetic modifications, and that combined inhibition of DNMT1 and EZH2 may offer a therapeutic benefit in subsets of PCa patients including in AA men. Acknowledgements: These studies were funded in part by NIH/NCI-7R01CA242839 (HK) and unrestricted funds from the LSU-LCMC Cancer Center, School of Medicine -LSUHSC, New Orleans (HK). Grateful to LCU-LCMC Genomics core for DNA sequencing Citation Format: Mousa Vatanmakanian, Sweaty Koul, Thangavel Chellappagounder, Hari K. Koul. Epigenetic regulation of SPDEF gene in RCC7/T cells, a line of malignant African-American prostate epithelial cells [abstract]. In: Proceedings of the 15th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2022 Sep 16-19; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2022;31(1 Suppl):Abstract nr A081.

IntroductionProstate cancer (PCa) presents a significant health challenge in men, with a substantial number of deaths attributed to metastatic castration resistant PCa (mCRPC). Moreover, African American men experience disproportionately high mortality rates due to PCa. This study delves into the pivotal role of SPDEF, a prostate specific Ets transcription factor, and its regulation by DNA methylation in the context of PCa progression.MethodsWe performed Epigenetic reprogramming using daily treatment with non-toxic dose of 5Aza-2-deoxycytidine (5Aza-dC) for two weeks to assess its impact on PDEF expression in prostate cancer cells. Next, we conducted functional studies on reprogrammed cells, including cell migration (wound-healing assay), invasion (Boyden-Chamber test), and proliferation (MTT assay) to comprehensively evaluate the consequences of altered PDEF expression. We used bisulfite sequencing (BSP) to examine DNA methylation at SPDEF promoter. Simultaneously, we utilized siRNA-mediated targeting of key DNMTs (DNMT1, DNMT3A, and DNMT3B) to elucidate their specific role in regulating PDEF. We measured mRNA and protein expressions using qRT-PCR and immune-blotting techniques, respectively.ResultsIn this report, we observed that: a) there is a gradual decrease in SPDEF expression with a concomitant increase in methylated CpG sites within the SPDEF gene during prostate cancer progression from lower to higher Gleason grade; b) Expression of DNMT’s (DNMT1, 3a and 3b) is increased during prostate cancer progression, and there is an inverse correlation between SPDEF and DNMT expression; c) SPDEF levels are decreased in RC77/T, a line of PCa cells from African American origin similar to PC3 and DU145 cells (CRPC cells), as compared to LNCaP cells , a line of androgen dependent cells,; d) the 5′ CpG island of SPDEF gene are hypermethylated in SPDEF-negative CRPC ( PC3, DU145 and RC77/T) cell lines but the same regions are hypomethylated in SPDEF-positive castrate sensitive (LNCaP) cell line ; (e) expression of SPDEF in PCa cells lacking SPDEF decreases cell migration and invasion, but has no significant effect on cell proliferation, and; (f) treatment with the demethylating agent, 5-aza-2′-deoxycytidine, or silencing of the DNMT’s by siRNA, partially restores SPDEF expression in SPDEF-negative PCa cell lines, and decreases cell migration and invasion.DiscussionThese results indicate hypermethylation is a prevalent mechanism for decreasing SPDEF expression during prostate cancer progression. The data demonstrate that loss of SPDEF expression in prostate cancer cells, a critical step in cellular plasticity, results from a potentially reversible process of aberrant DNA methylation. These studies suggest DMNT activity as a potential therapeutic vulnerability that can be exploited for limiting cellular plasticity, tumor progression, and therapy resistance in prostate cancer.

Objective: WW domain containing transcription regulator 1 (TAZ/WWTR1), one of the two downstream effectors of the Hippo pathway, is known to regulate cancer cell proliferation, migration and apoptosis by acting as a transcriptional co-activator. Recently, we described altered expression of yes-associated protein (YAP1) (a paralog of TAZ) in prostate cancer. However, the expression and function of TAZ and its regulation in prostate cancer is not well characterized. In the present study, we profiled expression patterns of TAZ in clinical data sets of PCa and evaluated the effects of PDEF on TAZ phosphorylation in prostate cancer (PCa) cells in culture. Material & Method: We analyzed the publicly available PCa datasets through Ualcan and c-Bioportal webservers. We transfected prostate cancer PC3 cells with PDEF or respective vector control. Protein levels of TAZ were analyzed by western blotting. Global changes in gene expression were analyzed using Affymetrix arrays followed by Gene Set Enrichment analysis. Results: Our analysis of publicly available PCa patient data in TCGA dataset, revealed a significant increase in TAZ mRNA levels in prostate cancer tissues as compared to normal prostate tissues (p=4.95E-08). Furthermore, we also found a significant gradual increase in TAZ mRNA expression during disease progression and metastasis. Our analysis of data sets in c-Bio portal revealed that patients with neuroendocrine PCa harbor much higher levels of TAZ mRNA as compared to CRPC phenotype. We also observed a negative correlation between PDEF and TAZ expression in CRPC/NEPC data set. We observed that the PC3 cells transfected with PDEF (PDEF-PC3) showed an increased phospho-TAZ as compared to the respective PC3 vector control (VC-PC3) suggesting that PDEF plays a critical role in modulating TAZ activity an important effector in Hippo signaling. Conclusions: These results provide first direct demonstration of elevated expression of TAZ in PCa, suggesting potential role of TAZ in prostate cancer. We also show for the first time increased TAZ phosphorylation in PCa cells by PDEF. Taken together with our recent work, our data suggest that PDEF modulates Hippo signaling by targeting both YAP1 and TAZ in PCa. Citation Format: Praveen K. Jaiswal, Suman Mohajan, Sweaty Koul, Hari K. Koul. Over-expression of WW domain containing transcription regulator 1 (TAZ/WWTR1) in prostate cancer and its modulation by prostate-derived ETS factor (PDEF) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1471.

In transitional cell carcinoma, the most common form of bladder cancer, overexpression of the matrix metalloproteinases MMP-2 and MMP-9 offers prognostic value as markers of disease-specific survival. These molecules have been implicated in metastasis of bladder cancer, but the underlying mechanisms through which they are controlled are poorly defined. In this study, we investigated a role of p38 mitogen-activated protein kinase (MAPK) in this process, using bladder cancer cell lines HTB9 and HTB5 that were derived from different tumor stages. p38 MAPK modulated MMP-2/9 mRNA levels at the levels of transcript stability and MMP-2/9 activity along with invasive capacity. We defined a downstream effector of p38 MAPK, MAPK-activated protein kinase 2 (MAPKAPK2), that was associated with MMP-2/9 activation. Ectopic expression of wild-type or constitutively active forms of MAPKAPK2 increased MMP-2/9 activities and invasive capacity. Conversely, p38 MAPK inhibition blocked the MAPKAPK2-mediated increase in MMP-2/9 activities and the invasive capacity of the cancer cells. Our findings implicate p38 MAPK and MAPKAPK2 in mediating bladder cancer invasion via regulation of MMP-2 and MMP-9 at the level of mRNA stability.

Objective: Deregulation of the translation initiation machinery is one of the critical steps for oncogenic mRNA translation in tumor cells. Eukaryotic translation initiation factor 4 gamma 1 (EIF4G1) is a crucial scaffold of translation initiation complex (EIF4F). Our recent studies suggest a role for EIF4G1 in multiple tumor types including prostate cancer progression. In the present study, we tested the unknown function of EIF4G1 in Enzalutamide resistant prostate cancer cells. Methods: We used enzalutamide resistant C4-2B (C4-2BENZR) and parental C4-2B cells for the current study. For the functional studies, we used shRNA targeting the EIF4G1 and pharmacological EIF4G-EIF4E complex inhibitor (4EGI-1). The functional assays such as clonogenic, cell proliferation, cell viability, trans-well migration/invasion, and prostasphere formation were performed. To further expand in vitro findings we employed, in-vivo tumor xenograft model derived from enzalutamide resistance C4-2B cells. Results: We found a higher level of EIF4G1 protein in ENZ resistance (C4-2B ENZR) cell lines as compared to parental C4-2B cell lines. Furthermore, knockdown of EIF4G1 by shRNA or treatment with 4EGI-1 inhibitor impaired the clonogenic potential, prostasphere formation, cell viability/proliferation, and cell migration/invasion in C4-2B ENZR cell line, suggesting a critical role of EIF4G1 in modulating enzalutamide resistance in CRPC cells. C4-2BENZR subcutaneous tumor xenograft treated with
combination of 4EGI-1 and ENZ were significantly reduced the tumor volume. Moreover 4EGI-1 sensitized ENZ Resistance C4-2B cells to Enzalutamide treatment in tumor xenograft model. Conclusions: Overall, the findings suggest that EIF4G1 could serve as a novel therapeutic target in overcoming therapeutic resistance to current treatments in PCa. Citation Format: Praveen K. Jaiswal, Sweaty Koul, Saikolappan Sankaralingam, Hari K. Koul. Therapeutic targeting of eukaryotic translation initiation factor 4 gamma 1 (EIF4G1) in enzalutamide resistant (ENZR) prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 396.

Androgen receptor (AR) signaling is involved in the development and progression of prostate cancer. Tumor microvasculature contributes to continual exposure of prostate cancer cells to hypoxia-reoxygenation, however, the role of hypoxia-reoxygenation in prostate cancer progression and modulation of AR signaling is not understood. In this study, we evaluated the effects of hypoxia-reoxygenation in LNCaP cells, a line of hormone responsive human prostate cancer cells. Our results demonstrate that hypoxia-reoxygenation resulted in increased survival, higher clonogenicity and enhanced invasiveness of these cells. Moreover, hypoxia-reoxygenation was associated with an increased AR activity independent of androgens as well as increased hypoxia inducible factor (HIF-1alpha) levels and activity. We also observed that the activation of p38 mitogen-activated protein (MAP) kinase pathway was an early response to hypoxia, and inhibition of p38 MAP kinase pathway by variety of approaches abolished hypoxia-reoxygenation induced increased AR activity as well as increased survival, clonogenicity and invasiveness. These results demonstrate a critical role for hypoxia-induced p38 MAP kinase pathway in androgen-independent AR activation in prostate cancer cells, and suggest that hypoxia-reoxygenation may select for aggressive androgen-independent prostate cancer phenotype.

The landscape of decoding the cancer intelligence systems which dictate the shape and architect of the tumor cells are challenging and very complex. The genetic alterations due to various external or internal insult allow tumor cells to evolve from the adverse conditions where reprograming the molecular mechanisms allowed some cells to sustain self-renewal and differentiation capability like stem cells, called cancer stem cells (CSCs). Epigenetic changes and disruption of redox balance have been known for their roles in cancer development and progression; however, their functions in genetic reprograming in context to cancer and CSCs have not been explored in detail. This chapter has shown some light in this area describing how ROS induced chromatin remodeling rewrite the code leading to CSCs emergence.

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/our-business/policies/article-withdrawal). This article is being retracted following correspondence from an Investigation Committee at the University of Colorado Denver. An internal investigation into this manuscript by the University of Colorado Denver, found evidence that there was image manipulation and that these actions warrant retraction to correct the scientific record. Bands on blot obscured or removed, apparent when the images are enhanced (Fig 4A p21 band "C" at 24hr, Fig 4B p21 band "C" at 24hr, and Fig 4B Cyclin A band "10" at 48 hr).

Background Current treatments against triple-negative breast cancer (TNBC) are ineffective due to the high rate of metastasis and therapy resistance. There is, therefore, a pressing need for novel and efficacious therapies against TNBC. The basal-like TNBC has a poor prognosis and a high metastasis rate compared to the luminal-like breast cancer subtypes. Here, set to determine the role of Sam Pointed Domain Ets Transcription Factor also known as Prostate-Derived Ets Factor (SPDEF/PDEF), in TNBC. Methods Clinical data were extracted from the METABRIC breast cancer project, hosted at the TCGA database. MDA-MB-231 and MDA 231-LM2-4175 cells were stably transfected with PDEF/control pBABE retroviral vectors. Cell migration/invasion assays were done to explore the effects of PDEF expression on the motility of TNBC cells. Proliferation was measured under 2D and 3D culture conditions. qRT-PCR and immunoblot were performed to visualize gene and protein expression. Data were graphed and analyzed using Graph Pad Prism Software 8 using one-way ANOVA and the unpaired two-tailed Student's t-test. All data were evaluated in triplicate against vector control cells. Results Basal gene and protein expression screening revealed that the expression of PDEF is significantly lower in highly metastatic breast cancer cells compared to the non-metastatic ones. Data analysis from clinical breast cancer METABRIC cohort revealed the loss of PDEF is associated with tumor metastasis, tumor grade, and poor patient survival. PDEF is lost in highly metastatic and therapy resistant TNBC cells. Re-expression of PDEF diminished cell migration and invasion in TNBC cells. Decreased migration and invasion in response to PDEF was not a result of decreased cell growth and proliferation or increased cell death but a result of suppression of EMT markers in TNBC cells. Conclusions PDEF expression inhibits cell migration and invasion partially by down-regulating EMT-related protein markers, suggesting a critical role for PDEF in suppressing TNBC cell metastasis.