Prostate Cancer Cell Growth Research Articles

Cell division cycle 42 effector protein 4 inhibits prostate cancer progression by suppressing ERK signaling pathway.

Prostate cancer (PCa) is the most common malignancy among men worldwide. The cell division cycle 42 effector protein 4 (CDC42EP4) functions downstream of CDC42, yet its role and molecular mechanisms in PCa remain unexplored. This study aimed to elucidate the role of CDC42EP4 in the progression of PCa and its underlying mechanisms. Bioinformatical analysis indicated that CDC42EP4 expression was significantly lower in PCa tissue compared to normal prostate tissue. Cellular phenotyping analysis suggested that CDC42EP4 markedly inhibited the proliferation, migration, and invasion of PCa cells. Xenograft tumor assays further demonstrated that CDC42EP4 suppressed the growth of PCa cells in vivo. Mechanistically, the study established that CDC42EP4 inhibited the ERK pathway in PCa cells. Additionally, the ERK pathway inhibitor PD0325901 was employed, revealing that PD0325901 significantly nullified the effects of CDC42EP4 on PCa cell proliferation, migration, and invasion. Collectively, our findings demonstrate that CDC42EP4 acts as a critical tumor suppressor gene, inhibiting PCa cell proliferation, migration, and invasion through the ERK pathway, thereby presenting potential targets for PCa therapy.

Prostate transmembrane androgen inducible protein 1 (PMEPA1): regulation and clinical implications.

Prostate transmembrane androgen inducible protein 1 (PMEPA1) can promote or inhibit prostate cancer cell growth based on the cancer cell response to the androgen receptor (AR). Further, it can be upregulated by transforming growth factor (TGF), which downregulates transforming growth factor-β (TGF-β) signaling by interfering with R-Smad phosphorylation to facilitate TGF-β receptor degradation. Studies have indicated the increased expression of PMEPA1 in some solid tumors and its functioning as a regulator of multiple signaling pathways. This review highlights the multiple potential signaling pathways associated with PMEPA1 and the role of the PMEPA1 gene in regulating prognosis, including transcriptional regulation and epithelial mesenchymal transition (EMT). Moreover, the relevant implications in and outside tumors, for example, as a biomarker and its potential functions in lysosomes have also been discussed.

First-line talazoparib with enzalutamide in HRR-deficient metastatic castration-resistant prostate cancer: the phase 3 TALAPRO-2 trial

Preclinical evidence has suggested an interplay between the androgen receptor, which largely drives the growth of prostate cancer cells, and poly(ADP-ribose) polymerase. This association provides a rationale for their co-inhibition for the treatment of metastatic castration-resistant prostate cancer (mCRPC), an area of unmet medical need. The phase 3 TALAPRO-2 study investigated combining the poly(ADP-ribose) polymerase inhibitor talazoparib with enzalutamide versus enzalutamide alone as first-line treatment of mCRPC. Patients were prospectively assessed for tumor alterations in DNA damage response genes involved in homologous recombination repair (HRR). Two cohorts were enrolled sequentially: an all-comers cohort that was enrolled first (cohort 1; N = 805 (169 were HRR-deficient)), followed by an HRR-deficient-only cohort (cohort 2; N = 230). We present results from the alpha-controlled primary analysis for the combined HRR-deficient population (N = 399). Patients were randomized in a 1:1 ratio to talazoparib or placebo, plus enzalutamide. The primary endpoint, radiographic progression-free survival, was met (median not reached at the time of the analysis for the talazoparib group versus 13.8 months for the placebo group; hazard ratio, 0.45; 95% confidence interval, 0.33 to 0.61; P < 0.0001). Data for overall survival, a key secondary endpoint, are immature but favor talazoparib (hazard ratio, 0.69; 95% confidence interval, 0.46 to 1.03; P = 0.07). Common adverse events in the talazoparib group were anemia, fatigue and neutropenia. Combining talazoparib with enzalutamide significantly improved radiographic progression-free survival in patients with mCRPC harboring HRR gene alterations, supporting talazoparib plus enzalutamide as a potential first-line treatment for these patients. ClinicalTrials.gov Identifier: NCT03395197.

LSD1 inhibitor hinders the demethylation of FOXA1 to inhibit prostate cancer progression

Abnormal activation of androgen receptor (AR) occurs in prostate cancer (PC) progression and metastasis. Lysine-specific demethylase 1 (LSD1), the first demethylating enzyme, regulates AR-mediated transcriptional activity. Considering the effect of Forkhead box protein A1 (FOXA1) on the expression of AR, estrogen receptor (ER) and tumor suppressor genes, this study investigated the demethylation of FOXA1 upon treatment with LSD1 inhibitors and assessed the biological behaviors of PC cells. PC cells were cultured and infected with viruses. After transient transfection, CWR22-RV1-Cas9 cells were selected by puromycin with expression of LSD1 detected by Western blot. Apart from measurement of formaldehyde production, immunoprecipitation and chromatin immunoprecipitation (ChIP) were performed, followed by ATAC-seq detection, and Western blot. The data indicated the association between LSD1-binding sites and high levels of FOXA1. LSD1 inhibitor treatment resulted in a dramatic decline in overall FOXA1 binding, significantly reducing chromosomal accessibility and also increasing lysine-methylated FOXA1 level, but it failed to affect H3K4me2 levels at LSD1-FOXA1 occupied sites. Overexpression of LSD1-WT obtained reverse outcome. Besides, LSD1 inhibition diminished binding of FOXA1 and restored lysine-methylation of FOXA1 in methylation-deficient cells with mutant K270R. Moreover, silencing of LSD1 suppressed CWR22-RV1 tumor growth, resulting in increased H3K4me2 and decreased AR-FL/V7 gene expression. K270me is demethylated by LSD1. LSD1 inhibitor disrupts FOXA1 chromatin association, blocks FOXA1 K270-demethylation and hinders AR binding, thereby suppressing PC cell growth.

Resistomycin Suppresses Prostate Cancer Cell Growth by Instigating Oxidative Stress, Mitochondrial Apoptosis, and Cell Cycle Arrest

Globally, prostate cancer is among the most threatening and leading causes of death in men. This study, therefore, aimed to search for an ideal antitumor strategy with high efficacy, low drug resistance, and no or few adverse effects. Resistomycin is a natural antibiotic derived from marine actinomycetes, and it possesses various biological activities. Prostate cancer cells (PC3) were treated with resistomycin (IC12.5: 0.65 or IC25: 1.3 µg/mL) or 5-fluorouracil (5-FU; IC25: 7 µg/mL) for 24 h. MTT assay and flow cytometry were utilized to assess cell viability and apoptosis. Oxidative stress, apoptotic-related markers, and cell cycle were also assessed. The results revealed that the IC50 of resistomycin and 5-FU on PC3 cells were 2.63 µg/mL and 14.44 µg/mL, respectively. Furthermore, treated cells with the high dose of resistomycin showed an increased number of apoptotic cells compared to those treated with the lower dose. Remarkable induction of reactive oxygen species generation and lactate dehydrogenase (LDH) leakage with high malondialdehyde (MDA), carbonyl protein (CP), and 8-hydroxyguanosine (8-OHdG) contents were observed in resistomycin-treated cells. In addition, marked declines in glutathione (GSH), superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) in PC3 cells subjected to resistomycin therapy were observed. Resistomycin triggered observable cell apoptosis by increasing Bax, caspase-3, and cytosolic cytochrome c levels and decreasing Bcl-2 levels. In addition, notable downregulation of proliferating cell nuclear antigen (PCNA) and cyclin D1 was observed in resistomycin-treated cancerous cells. According to this evaluation, the antitumor potential of resistomycin, in a concentration-dependent manner, in prostate cancer cells was achieved by triggering oxidative stress, mitochondrial apoptosis, and cell cycle arrest in cancer cells. In conclusion, our investigation suggests that resistomycin can be considered a starting point for developing new chemotherapeutic agents for human prostate cancer.

Glucocorticoid treatment influences prostate cancer cell growth and the tumor microenvironment via altered glucocorticoid receptor signaling in prostate fibroblasts

Despite significant therapeutic advances in recent years, treatment of metastatic prostate cancer (PCa) remains palliative, owing to the inevitable occurrence of drug resistance. There is increasing evidence that epithelial glucocorticoid receptor (GR) signaling and changes in the tumor-microenvironment (TME) play important roles in this process. Since glucocorticoids (GCs) are used as concomitant medications in the course of PCa treatment, it is essential to investigate the impact of GCs on stromal GR signaling in the TME. Therefore, general GR mRNA and protein expression was assessed in radical prostatectomy specimens and metastatic lesions. Elevated stromal GR signaling after GC treatment resulted in altered GR-target gene, soluble protein expression, and in a morphology change of immortalized and primary isolated cancer-associated fibroblasts (CAFs). Subsequently, these changes affected proliferation, colony formation, and 3D-spheroid growth of multiple epithelial PCa cell models. Altered expression of extra-cellular matrix (ECM) and adhesion-related proteins led to an ECM remodeling. Notably, androgen receptor pathway inhibitor treatments did not affect CAF viability. Our findings demonstrate that GC-mediated elevated GR signaling has a major impact on the CAF secretome and the ECM architecture. GC-treated fibroblasts significantly influence epithelial tumor cell growth and must be considered in future therapeutic strategies.

A novel intronic circular RNA circFGFR1int2 up-regulates FGFR1 by recruiting transcriptional activators P65/FUS and suppressing miR-4687-5p to promote prostate cancer progression

Fibroblast growth factor receptor 1 (FGFR1) is a core component of the FGFs/FGFR pathway that activates multiple signalling pathways, including ERK1/2, PI3K/AKT, PLCγ, and NF-κB. Aberrant expression of FGFR1 due to gene amplification, chromosome rearrangement, point mutation, and epigenetic deregulations, have been reported in various cancers. FGFR1 overexpression has also been reported in prostate cancer (PCa), but the underlining mechanisms are not clear. Here we report a novel circular RNA, circFGFR1int2, derived from intron 2 of FGFR1 gene, which is overexpressed in PCa and associated with tumor progression. Importantly, we show that circFGFR1int2 facilitates FGFR1 transcription by recruiting transcription activators P65/FUS and by interacting with FGFR1 promoter. Moreover, we show that circFGFR1int2 suppresses post-transcriptional inhibitory effects of miR-4687-5p on FGFR1 mRNA. These mechanisms synergistically promote PCa cell growth, migration, and invasion. Overexpression of circFGFR1int2 is significantly correlated with higher tumor grade, Gleason score, and PSA level, and is a significant unfavorable prognosticator for CRPC-free survival (CFS) (RR = 3.277, 95% confidence interval: 1.192–9.009; P = 0.021). These findings unravelled novel mechanisms controlling FGFR1 gene expression by intronic circRNA and its potential clinicopathological utility as a diagnostic or therapeutic target.Graphic

Methylation of the epigenetic JMJD2D protein by SET7/9 promotes prostate tumorigenesis.

How the function of the JMJD2D epigenetic regulator is regulated or whether it plays a role in prostate cancer has remained elusive. We found that JMJD2D was overexpressed in prostate tumors, stimulated prostate cancer cell growth and became methylated by SET7/9 on K427. Mutation of this lysine residue in JMJD2D reduced the ability of DU145 prostate cancer cells to grow, invade and form tumors and elicited extensive transcriptomic changes. This included downregulation of CBLC, a ubiquitin ligase gene with hitherto unknown functions in prostate cancer, and upregulation of PLAGL1, a transcription factor with reported tumor suppressive characteristics in the prostate. Bioinformatic analyses indicated that CBLC expression was elevated in prostate tumors. Further, downregulation of CBLC largely phenocopied the effects of the K427 mutation on DU145 cells. In sum, these data have unveiled a novel mode of regulation of JMJD2D through lysine methylation, illustrated how this can affect oncogenic properties by influencing expression of the CBLC gene, and established a pro-tumorigenic role for CBLC in the prostate. A corollary is that JMJD2D and CBLC inhibitors could have therapeutic benefits in the treatment of prostate and possibly other cancers.

MT1G, an emerging ferroptosis-related gene: A novel prognostic biomarker and indicator of immunotherapy sensitivity in prostate cancer.

Prostate cancer is a leading cause of cancer-related deaths in men worldwide. Despite advances in treatment strategies, there is still a need for novel therapeutic targets and approaches. Ferroptosis has emerged as a critical process in the development and progression of several cancers, including prostate cancer (PCA). In this study, we investigate the role of MT1G, a gene implicated in immune responses and ferroptosis, in the pathogenesis of PCA. Our objective is to elucidate its prognostic significance and its impact on the tumor microenvironment, while exploring its potential in enhancing the sensitivity to immune checkpoint inhibitor (ICI) therapy. We utilized a combination of in silico analysis and experimental techniques to investigate the role of MT1G in PCA. First, we analyzed large-scale genomic datasets to assess the expression pattern and prognostic significance of MT1G in PCA patients. Subsequently, we performed functional assays to explore the impact of MT1G in PCA and its potential involvement in modulating immune responses. In addition, we conducted in vivo experiments to evaluate the effect of MT1G on tumor growth and response to ICI therapy. Our analysis revealed that MT1G expression is significantly downregulated in PCA tissues compared to normal prostate tissues and is associated with poor prognosis. Furthermore, MT1G overexpression inhibited the growth of PCA cells in vitro and in vivo. Importantly, we found that MT1G regulates the tumor microenvironment by modulating immune cell infiltration and inhibiting immunosuppressive factors. Furthermore, our study reveals a significant correlation between MT1G expression levels and the response to immune checkpoint inhibitor (ICI) therapy in prostate cancer (PCA) patients, as MT1G upregulation leads to an increase in PDL-1 expression. These findings underscore the potential of MT1G as a promising predictive biomarker for ICI therapy response in PCA patients. Our study elucidates the pivotal role played by MT1G in the pathogenesis of prostate cancer (PCA) and its profound implications for prognosis. Moreover, it raises the intriguing possibility that MT1G could pave the way for novel therapeutic approaches in PCA treatment. This potential arises from its ability to orchestrate immune infiltration within the tumor microenvironment, consequently enhancing sensitivity to immune checkpoint inhibitor (ICI) therapy. Therefore, our findings hold substantial promise for advancing our comprehension of PCA and exploring innovative therapeutic strategies.

Targeting DGAT1 inhibits prostate cancer cells growth by inducing autophagy flux blockage via oxidative stress.

Impaired macroautophagy/autophagy flux has been implicated in the treatment of prostate cancer (PCa). However, the mechanism underlying autophagy dysregulation in PCa remains unknown. In the current study, we investigated the role of diacylglycerol acyltransferases 1 (DGAT1) and its potential effects on cellular energy homeostasis and autophagy flux in PCa. The results of immunohistochemical staining suggested that DGAT1 expression was positively corrected with tumor stage and node metastasis, indicating DGAT1 is an important factor involved in the development and progression of PCa. Furthermore, targeting DGAT1 remarkably inhibited cell proliferation in vitro and suppressed PCa growth in xenograft models by triggering severe oxidative stress and subsequently autophagy flux blockage. Mechanically, DGAT1 promoted PCa progression by maintaining cellular energy homeostasis, preserving mitochondrial function, protecting against reactive oxygen species, and subsequently promoting autophagy flux via regulating lipid droplet formation. Moreover, we found that fenofibrate exhibits as an upstream regulator of DGAT1. Fenofibrate performed its anti-PCa effect involved the aforementioned mechanisms, and partially dependent on the regulation of DGAT1. Collectively. These findings indicate that DGAT1 regulates PCa lipid droplets formation and is essential for PCa progression. Targeting DGAT1 might be a promising method to control the development and progression of PCa. Schematic representation of DGAT1 affects autophagy flux by regulating lipid homeostasis and maintaining mitochondrial function in prostate cancer (PCa). PCa is characterized up-regulation of DGAT1, leading to the translocation of free fatty acids into lipid droplets, thereby preventing PCa cell from lipotoxicity. Inhibition of DGAT1 suppresses growth of PCa by inducing oxidative stress and subsequently autophagy flux blockage. Further, the current results revealed that fenofibrate exhibits as an upstream regulator of DGAT1, and fenofibrate plays an anti-PCa role partially dependent on the regulation of DGAT1, suggesting a potential therapeutic approach to ameliorate this refractory tumor.

Synergistic effect of docetaxel combined with a novel multi-target inhibitor CUDC-101 on inhibiting human prostate cancer

Histone deacetylases (HDACs) are commonly overexpressed in several types of human cancers, including prostate cancer (PCa). Histone deacetylase inhibitors (HDACis) are emerging as promising tools for cancer therapy. However, there is still a need to understand their anti-tumor effects and the mechanisms underlying their action. In our study, we investigated the effects of co-treatment with CUDC-101 and docetaxel (DTX) on cell growth, clonogenicity, invasion and migration of PCa cells both in vitro, and in a xenograft mouse model. We found that the combination of CUDC-101 and DTX significantly reduced tumor growth, as evidenced by lower tumor weight and volumes. Moreover, apoptotic cell death was increased in the combination group compared to either drug alone or control. Mechanistically, we observed that the combined treatment of CUDC-101 with DTX suppressed the progression of PCa cell lines through the AKT and ERK1/2 signaling pathways. Additionally, this combination treatment reversed EMT by modulating the expression of key markers such as E-cadherin, vimentin, Snail and MMP-9. To conclude, these results demonstrated that the combination of CUDC-101 with DTX had a synergistic and significantly improved anti-carcinogenic effect. This combination may serve as a potential strategy for clinical treatment and prognosis improvement in PCa.

Prognostic and therapeutic potential of senescent stromal fibroblasts in prostate cancer.

The stromal component of the tumour microenvironment in primary and metastatic prostate cancer can influence and promote disease progression. Within the prostatic stroma, fibroblasts are one of the most prevalent cell types associated with precancerous and cancerous lesions; they have a vital role in the structural composition, organization and integrity of the extracellular matrix. Fibroblasts within the tumour microenvironment can undergo cellular senescence, which is a stable arrest of cell growth and a phenomenon that is emerging as a recognized hallmark of cancer. Supporting the idea that cellular senescence has a pro-tumorigenic role, a subset of senescent cells exhibits a senescence-associated secretory phenotype (SASP), which, along with increased inflammation, can promote prostate cancer cell growth and survival. These cellular characteristics make targeting senescent cells and/or modulating SASP attractive as a potential preventive or therapeutic option for prostate cancer.

Cyclosporin A inhibits prostate cancer growth through suppression of E2F8 transcription factor in a MELK‑dependent manner.

The treatment of advanced prostate cancer remains a formidable challenge due to the limited availability of effective treatment options. Therefore, it is imperative to identify promising druggable targets that provide substantial clinical benefits and to develop effective treatment strategies to overcome therapeutic resistance. Cyclosporin A (CsA) showed an anticancer effect on prostate cancer in cultured cell and xenograft models. E2F8 was identified as a master transcription factor that regulated a clinically significant CsA specific gene signature. The expression of E2F8 increased during prostate cancer progression and high levels of E2F8 expression are associated with a poor prognosis in patients with prostate cancer. MELK was identified as a crucial upstream regulator of E2F8 expression through the transcriptional regulatory network and Bayesian network analyses. Knockdown of E2F8 or MELK inhibited cell growth and colony formation in prostate cancer cells. High expression levels of E2F8 and androgen receptor (AR) are associated with a worse prognosis in patients with prostate cancer compared with low levels of both genes. The inhibition of E2F8 improved the response to AR blockade therapy. These results suggested that CsA has potential as an effective anticancer treatment for prostate cancer, while also revealing the oncogenic role of E2F8 and its association with clinical outcomes in prostate cancer. These results provided valuable insight into the development of therapeutic and diagnostic approaches for prostate cancer.

Targeting aberrant sialylation and fucosylation in prostate cancer cells using potent metabolic inhibitors.

Aberrant glycosylation is a hallmark of cancer and is not just a consequence, but also a driver of a malignant phenotype. In prostate cancer, changes in fucosylated and sialylated glycans are common and this has important implications for tumor progression, metastasis, and immune evasion. Glycans hold huge translational potential and new therapies targeting tumor-associated glycans are currently being tested in clinical trials for several tumor types. Inhibitors targeting fucosylation and sialylation have been developed and show promise for cancer treatment, but translational development is hampered by safety issues related to systemic adverse effects. Recently, potent metabolic inhibitors of sialylation and fucosylation were designed that reach higher effective concentrations within the cell, thereby rendering them useful tools to study sialylation and fucosylation as potential candidates for therapeutic testing. Here, we investigated the effects of global metabolic inhibitors of fucosylation and sialylation in the context of prostate cancer progression. We find that these inhibitors effectively shut down the synthesis of sialylated and fucosylated glycans to remodel the prostate cancer glycome with only minor apparent side effects on other glycan types. Our results demonstrate that treatment with inhibitors targeting fucosylation or sialylation decreases prostate cancer cell growth and downregulates the expression of genes and proteins important in the trajectory of disease progression. We anticipate our findings will lead to the broader use of metabolic inhibitors to explore the role of fucosylated and sialylated glycans in prostate tumor pathology and may pave the way for the development of new therapies for prostate cancer.

Assessing the Potential of Small Peptides for Altering Expression Levels of the Iron-Regulatory Genes FTH1 and TFRC and Enhancing Androgen Receptor Inhibitor Activity in In Vitro Prostate Cancer Models.

Recent research highlights the key role of iron dyshomeostasis in the pathogenesis of prostate cancer (PCa). PCa cells are heavily dependent on bioavailable iron, which frequently results in the reprogramming of iron uptake and storage pathways. Although advanced-stage PCa is currently incurable, bioactive peptides capable of modulating key iron-regulatory genes may constitute a means of exploiting a metabolic adaptation necessary for tumor growth. Recent annual increases in PCa incidence have been reported, highlighting the urgent need for novel treatments. We examined the ability of LNCaP, PC3, VCaP, and VCaP-EnzR cells to form colonies in the presence of androgen receptor inhibitors (ARI) and a series of iron-gene modulating oligopeptides (FT-001-FT-008). The viability of colonies following treatment was determined with clonogenic assays, and the expression levels of FTH1 (ferritin heavy chain 1) and TFRC (transferrin receptor) were determined with quantitative polymerase chain reaction (PCR). Peptides and ARIs combined significantly reduced PCa cell growth across all phenotypes, of which two peptides were the most effective. Colony growth suppression generally correlated with the magnitude of concurrent increases in FTH1 and decreases in TFRC expression for all cells. The results of this study provide preliminary insight into a novel approach at targeting iron dysmetabolism and sensitizing PCa cells to established cancer treatments.

AKAP2-anchored protein phosphatase 1 controls prostatic neuroendocrine carcinoma cell migration and invasion

Prostate cancer (PC) is the second leading cause of cancer-related death in men. The growth of primary prostate cancer cells relies on circulating androgens and thus the standard therapy for the treatment of localized and advanced PC is the androgen deprivation therapy. Prostatic neuroendocrine carcinoma (PNEC) is an aggressive and highly metastatic subtype of prostate cancer, which displays poor prognosis and high lethality. Most of PNECs develop from prostate adenocarcinoma in response to androgen deprivation therapy, however the mechanisms involved in this transition and in the elevated biological aggressiveness of PNECs are poorly defined. Our current findings indicate that AKAP2 expression is dramatically upregulated in PNECs as compared to non-cancerous prostate tissues. Using a PNEC cell model, we could show that AKAP2 is localized both intracellularly and at the cell periphery where it colocalizes with F-actin. AKAP2 and F-actin interact directly through a newly identified actin-binding domain located on AKAP2. RNAi-mediated silencing of AKAP2 promotes the phosphorylation and deactivation of cofilin, a protein involved in actin turnover. This effect correlates with a significant reduction in cell migration and invasion. Co-immunoprecipitation experiments and proximity ligation assays revealed that AKAP2 forms a complex with the catalytic subunit of protein phosphatase 1 (PP1) in PNECs. Importantly, AKAP2-mediated anchoring of PP1 to the actin cytoskeleton regulates cofilin dephosphorylation and activation, which, in turn, enhances F-actin dynamics and favors migration and invasion. In conclusion, this study identified AKAP2 as an anchoring protein overexpressed in PNECs that controls cancer cell invasive properties by regulating cofilin phosphorylation.

Identification of the mitochondrial protein POLRMT as a potential therapeutic target of prostate cancer

RNA polymerase mitochondria (POLRMT) is essential for mitochondrial transcription machinery and other mitochondrial functions. Its expression and potential functions in prostate cancer were explored here. The Cancer Genome Atlas prostate cancer cohort (TCGA PRAD) shows that POLRMT mRNA expression is upregulated in prostate cancer tissues and POLRMT upregulation is correlated with poor patients’ survival. POLRMT mRNA and protein levels were upregulated in local prostate cancer tissues and different primary/immortalized prostate cancer cells. Genetic depletion of POLRMT, using viral shRNA or CRISPR/Cas9 gene editing methods, impaired mitochondrial functions in prostate cancer cells, leading to mitochondrial depolarization, oxidative stress, mitochondria complex I inhibition, and ATP depletion. Moreover, POLRMT depletion resulted in robust inhibition of prostate cancer cell viability, proliferation, and migration, and provoked apoptosis. Conversely, prostate cancer cell proliferation, migration, and ATP contents were strengthened following ectopic POLRMT overexpression. In vivo, intratumoral injection of POLRMT shRNA adeno-associated virus impeded prostate cancer xenograft growth in nude mice. POLRMT silencing, oxidative stress, and ATP depletion were detected in POLRMT shRNA-treated prostate cancer xenograft tissues. IMT1 (inhibitor of mitochondrial transcription 1), the first-in-class POLRMT inhibitor, inhibited prostate cancer cell growth in vitro and in vivo. Together, overexpressed POLRMT is an important mitochondrial protein for prostate cancer cell growth, representing a novel and promising diagnostic and therapeutic oncotarget.

THU476 Role Of Mitochondrial Sirtuins 3 And 5 On Glutamine Addiction In Prostate Cancer Cell

Abstract Disclosure: K.M. Hasan: None. T.C. Friedman: None. W. Chen: None. Myc-transformed and hypoxic cancer cells are sensitive to glutamine deprivation. Reprogramming to glutamine addiction helps to maintain the TCA cycle pool and anaplerosis that provide cancer cells energy and various macromolecules critical for rapid proliferation. However, the mechanism of glutamine addiction has yet to be fully understood. Here we explore the effect of mitochondrial sirtuins (Sirt3 and Sirt5) on glutamine metabolism in prostate cancer (PCa) cell. We used lentiviral-based knockdown or overexpression methods to examine the effect of Sirt3 and Sirt5 on the growth and proliferation of PC3 and LnCap cells. Cells were grown in both regular or glutamine-free liquid and soft agar media to investigate the effect of Sirt3 and Sirt5 on anchorage-dependent or independent growth, respectively. Cells after the knockdown of Sirt3 and Sirt5 were also grown in media supplemented with cell permeable dimethyl ketoglutarate (DMK), an alternative to ketoglutarate to continue the TCA cycle in the absence of active glutamine metabolism. We showed that anchorage-independent growth (AIG) of PCa cells relied on mitochondrial sirtuins (mtSirts). Inhibition of Sirt3 and Sirt5 activity impaired AIG, and the inhibitory effect was rescued by supplying DMK, suggesting the impact of mtSirts on glutamine metabolism. Most intriguing, our results demonstrated that Sirt3 overexpression enhanced AIG, which can be suppressed by knockdown glutamate dehydrogenase (GDH), suggesting that Sirt3 upregulated glutamine metabolism through GDH activation. Indeed, we found that silencing of Sirt3 and Sirt5 induced the acetylation of GDH and decreased the GDH activity. In agreement, we further observed that glutamine was essential for AIG of prostate cancer cells, and the addition of DMK in a glutamine-free medium rescued the growth, implying that PCa cells are addicted to glutamine. Finally, we showed that the knockdown of Sirt3 and Sirt5 impaired the tumorigenicity of PC3 cells in vivo mouse xenograft model. Thus, we concluded that sirtuins-mediated GDH regulation is a crucial process in the metabolic adaptation of PCa cells that can be a therapeutic target. Presentation: Thursday, June 15, 2023

Sennoside A induces autophagic death of prostate cancer via inactivation of PI3K/AKT/mTOR axis.

Prostate cancer (PC) is the most common malignancy in male reproductive system. Sennoside A (SA) is an anthraquinone active ingredient extracted from Rheum officinale Baill., which exerts anti-tumor activity on different tumors. In the present study, the toxicity of SA on PC3 and DU 145 cells was detected via CCK-8. The effects of SA on growth, apoptosis, and autophagy were determined through CCK-8, Hoechst stain, flow cytometry, western blot, and immunofluorescence examinations. An in vivo experiment was performed in xenografted mice with intraperitoneal introduction of 10mg/kg SA and validated via TUNEL, immunohistochemistry and western blot. The results showed that SA inhibited the cell viability with a IC50 value of 52.36 and 67.48 µM in DU 145 and PC3 cells respectively, and enhanced the apoptosis of PC3 and DU 145 cells. Additionally, SA elevated the relative LC3B expression, and the relative protein expression of LC3II/LC3I and Beclin-1, but diminished the P62 protein expression. The relative protein level of p-PI3K/PI3K, p-AKT/AKT and p-mTOR/mTOR was reduced with SA treatment, which was verified by the 740 Y-P application. The 740 Y-P treatments also restored the SA-induced the cell viability, apoptosis rate and relative LC3B expression. Meanwhile, SA inhibited the growth of PC cell and the relative protein level of PI3K/AKT/mTOR axis in vivo. Taken together, SA regulated the proliferation, apoptosis and autophagy via inactivating the PI3K/AKT/mTOR axis in PC.

RNA Interference against ATP as a Gene Therapy Approach for Prostate Cancer.

Chemotherapeutic agents targeting energy metabolism have not achieved satisfactory results in different types of tumors. Herein, we developed an RNA interference (RNAi) method against adenosine triphosphate (ATP) by constructing an interfering plasmid-expressing ATP-binding RNA aptamer, which notably inhibited the growth of prostate cancer cells through diminishing the availability of cytoplasmic ATP and impairing the homeostasis of energy metabolism, and both glycolysis and oxidative phosphorylation were suppressed after RNAi treatment. Further identifying the mechanism underlying the effects of ATP aptamer, we surprisingly found that it markedly reduced the activity of membrane ionic channels and membrane potential which led to the dysfunction of mitochondria, such as the decrease of mitochondrial number, reduction in the respiration rate, and decline of mitochondrial membrane potential and ATP production. Meanwhile, the shortage of ATP impeded the formation of lamellipodia that are essential for the movement of cells, consequently resulting in a significant reduction of cell migration. Both the downregulation of the phosphorylation of AMP-activated protein kinase (AMPK) and endoplasmic reticulum kinase (ERK) and diminishing of lamellipodium formation led to cell apoptosis as well as the inhibition of angiogenesis and invasion. In conclusion, as the first RNAi modality targeting the blocking of ATP consumption, the present method can disturb the respiratory chain and ATP pool, which provides a novel regime for tumor therapies..