Molecular landscape for risk prediction and personalized therapeutics of castration-resistant prostate cancer: at a glance.

Prostate cancer (PCa) is commonly occurred with high incidence in men worldwide, and many patients will be eventually suffered from the dilemma of castration-resistance with the time of disease progression. Castration-resistant PCa (CRPC) is an advanced subtype of PCa with heterogeneous carcinogenesis, resulting in poor prognosis and difficulties in therapy. Currently, disorders in androgen receptor (AR)-related signaling are widely acknowledged as the leading cause of CRPC development, and some non-AR-based strategies are also proposed for CRPC clinical analyses. The initiation of CRPC is a consequence of abnormal interaction and regulation among molecules and pathways at multi-biological levels. In this study, CRPC-associated genes, RNAs, proteins, and metabolites were manually collected and integrated by a comprehensive literature review, and they were functionally classified and compared based on the role during CRPC evolution, i.e., drivers, suppressors, and biomarkers, etc. Finally, translational perspectives for data-driven and artificial intelligence-powered CRPC systems biology analysis were discussed to highlight the significance of novel molecule-based approaches for CRPC precision medicine and holistic healthcare.

Rare histologic transformation of a CTNNB1 (ß-catenin) mutated prostate cancer with aggressive clinical course.

BACKGROUND: Catenin (Cadherin-Associated Protein), Beta 1 (CTNNB1) genomic alterations are rare in prostate cancer (PCa). Gain-of-function mutations lead to overexpression of ß-catenin, with consequent hyperactivation of the Wnt/ß-catenin signaling pathway, implicated in PCa progression and treatment resistance. To date, successful targeted treatment options for Wnt/ß-catenin - driven PCa are lacking. METHODS: We report a rare histologic transformation of a CTNNB1 (ß-catenin) mutated metastatic castration resistant prostate cancer (mCRPC), clinically characterized by highly aggressive disease course. We histologically and molecularly characterized the liver metastatic tumor samples, as well as successfully generated patient-derived organoids (PDOs) and patient-derived xenograft (PDX) from a liver metastasis. We used the generated cell models for further molecular characterization and drug response assays. RESULTS: Immunohistochemistry of liver metastatic biopsies and PDX tumor showed lack of expression of typical PCa (e.g., AR, PSA, PSAP, ERG) or neuroendocrine markers (synaptophysin), compatible with double-negative CRPC, but was positive for nuclear ß-catenin expression, keratin 7 and 34ßE12. ERG rearrangement was confirmed by fluorescent in situ hybridization (FISH). Drug response assays confirmed, in line with the clinical disease course, lack of sensitivity to common drugs used in mCRPC (e.g., enzalutamide, docetaxel). The casein kinase 1 (CK1) inhibitor IC261 and the tankyrase 1/2 inhibitor G700-LK showed modest activity. Moreover, despite harbouring a CTNNB1 mutation, PDOs were largely insensitive to SMARCA2/4- targeting PROTAC degraders and inhibitor. CONCLUSIONS: The reported CTNNB1-mutated mCRPC case highlights the potential challenges of double-negative CRPC diagnosis and underlines the relevance of further translational research to enable successful targeted treatment of rare molecular subtypes of mCRPC.

PROTACs targeting androgen receptor signaling: Potential therapeutic agents for castration-resistant prostate cancer.

After the initial androgen deprivation therapy (ADT), part of the prostate cancer may continuously deteriorate into castration-resistant prostate cancer (CRPC). The majority of patients suffer from the localized illness at primary diagnosis that could rapidly assault other organs. This disease stage is referred as metastatic castration-resistant prostate cancer (mCRPC). Surgery and radiation are still the treatment of CRPC, but have some adverse effects such as urinary symptoms and sexual dysfunction. Hormonal castration therapy interfering androgen receptor (AR) signaling pathway is indispensable for most advanced prostate cancer patients, and the first- and second-generation of novel AR inhibitors could effectively cure hormone sensitive prostate cancer (HSPC). However, the resistance to these chemical agents is inevitable, so many of patients may experience relapses. The resistance to AR inhibitor mainly involves AR mutation, splice variant formation and amplification, which indicates the important role in CRPC. Proteolysis-targeting chimera (PROTAC), a potent technique to degrade targeted protein, has recently undergone extensive development as a biological tool and therapeutic drug. This technique has the potential to become the next generation of antitumor therapeutics as it could overcome the shortcomings of conventional small molecule inhibitors. In this review, we summarize the molecular mechanisms on PROTACs targeting AR signaling for CRPC, hoping to provide insights into drug development and clinical medication.

Cyclin-dependent kinase 12 deficiency reprogrammes cellular metabolism to alleviate ferroptosis potential and promote the progression of castration-resistant prostate cancer.

BACKGROUND: Cyclin-dependent kinase 12 (CDK12)-deficient prostate cancer defines a subtype of castration-resistant prostate cancer (CRPC) with a poor prognosis. Current therapy, including PARP inhibitors, shows minimal treatment efficacy for this subtype of CRPC, and the underlying mechanism remains elusive. METHODS: Based on bioinformatics analysis, we evaluated the relationship between CDK12 deficiency and prostate cancer patient's prognosis and treatment resistance. Furthermore, we used CRISPR-Cas9 technology and mass spectrometry-based metabolomic profiling to reveal the metabolic characteristics of CDK12-deficient CRPC. To elucidate the specific mechanisms of CDK12 deficiency-mediated CRPC metabolic reprogramming, we utilized cell RNA-seq profiling and other molecular biology techniques, including cellular reactive oxygen species probes, mitochondrial function assays, ChIP-qPCR and RNA stability analyses, to clarify the role of CDK12 in regulating mitochondrial function and its contribution to ferroptosis. Finally, through in vitro drug sensitivity testing and in vivo experiments in mice, we identified the therapeutic effects of the electron transport chain (ETC) inhibitor IACS-010759 on CDK12-deficient CRPC. RESULTS: CDK12-deficient prostate cancers reprogramme cellular energy metabolism to support their aggressive progression. In particular, CDK12 deficiency enhanced the mitochondrial respiratory chain for electronic transfer and ATP synthesis to create a ferroptosis potential in CRPC cells. However, CDK12 deficiency downregulated ACSL4 expression, which counteracts the lipid oxidation stress, leading to the escape of CRPC cells from ferroptosis. Furthermore, targeting the ETC substantially inhibited the proliferation of CDK12-deficient CRPC cells in vitro and in vivo, suggesting a potential new target for the therapy of CDK12-deficient prostate cancer. CONCLUSIONS: Our findings show that energy and lipid metabolism in CDK12-deficient CRPC work together to drive CRPC progression and provide a metabolic insight into the worse prognosis of CDK12-deficient prostate cancer patients. KEY POINTS: CDK12 deficiency promotes castration-resistant prostate cancer (CRPC) progression by reprogramming cellular metabolism. CDK12 deficiency in CRPC leads to a more active mitochondrial electron transport chain (ETC), ensuring efficient cell energy supply. CDK12 phosphorylates RNA Pol II to ensure the transcription of ACSL4 to regulate ferroptosis. Mitochondrial ETC inhibitors exhibit better selectivity for CDK12-deficient CRPC cells, offering a promising new therapeutic approach for this subtype of CRPC patients.

Patient-derived castration-resistant prostate cancer model revealed CTBP2 upregulation mediated by OCT1 and androgen receptor.

BACKGROUND: Prostate cancer is dependent on androgen receptor (AR) signaling, and androgen deprivation therapy (ADT) has proven effective in targeting prostate cancer. However, castration-resistant prostate cancer (CRPC) eventually emerges. AR signaling inhibitors (ARSI) have been also used, but resistance to these agents develops due to genetic AR alterations and epigenetic dysregulation. METHODS: In this study, we investigated the role of OCT1, a member of the OCT family, in an AR-positive CRPC patient-derived xenograft established from a patient with resistance to ARSI and chemotherapy. We conducted a genome-wide analysis chromatin immunoprecipitation followed by sequencing and bioinformatic analyses using public database. RESULTS: Genome-wide analysis of OCT1 target genes in PDX 201.1 A revealed distinct OCT1 binding sites compared to treatment-naïve cells. Bioinformatic analyses revealed that OCT1-regulated genes were associated with cell migration and immune system regulation. In particular, C-terminal Binding Protein 2 (CTBP2), an OCT1/AR target gene, was correlated with poor prognosis and immunosuppressive effects in the tumor microenvironment. Metascape revealed that CTBP2 knockdown affects genes related to the immune response to bacteria. Furthermore, TISIDB analysis suggested the relationship between CTBP2 expression and immune cell infiltration in prostate cancer, suggesting that it may contribute to immune evasion in CRPC. CONCLUSIONS: Our findings shed light on the genome-wide network of OCT1 and AR in AR-positive CRPC and highlight the potential role of CTBP2 in immune response and tumor progression. Targeting CTBP2 may represent a promising therapeutic approach for aggressive AR-positive CRPC. Further validation will be required to explore novel therapeutic strategies for CRPC management.

Dual FDG/PSMA PET imaging to predict lesion-based progression of mCRPC during PSMA-RLT.

Candidates for prostate-specific membrane antigen (PSMA)-targeted radioligand therapy (RLT) of metastatic castration-resistant prostate cancer (mCRPC) frequently have "mismatch" lesions with pronounced 18-fluorodeoxyglucose ([18F]FDG) but attenuated PSMA ligand uptake on positron emission tomography (PET). However, no quantitative criteria yet exist to identify mismatch lesions and predict their response to RLT. To define such criteria, we retrospectively analyzed 267 randomly-selected glucometabolic mCRPC metastases from 22 patients. On baseline PET, we determined [18F]FDG and [68Ga]Ga-PSMA-11 maximum standardized uptake value (SUVmax), and calculated the [18F]FDG SUVmax/[68Ga]Ga-PSMA-11 SUVmax quotient (FPQ). From follow-up [18F]FDG PET after two lutetium-177-PSMA-617 RLT cycles, we evaluated the treatment response and categorized the lesions into three subgroups (partial remission, stable disease, progression) based on change in [18F]FDG SUVmax. Lastly, we compared the baseline PET variables in progressing versus non-progressing lesions. Variables differing significantly, and a score incorporating them, were assessed via receiver operator characteristic (ROC) curve analysis, regarding ability to predict lesional progression, with area under the curve (AUC) as metric. Cut-offs with optimal sensitivity and specificity were determined using the maximum value of Youden's index. Fifty-one of 267 lesions (19.1%) progressed, 102/267 (38.2%) manifested stable disease, and 114/267 (42.7%) partially responded after two RLT cycles. At baseline, median [68Ga]Ga-PSMA-11 SUVmax was significantly lower (p < 0.001), median FPQ significantly higher (p < 0.001), and median [18F]FDG SUVmax similar in progressing versus non-progressing lesions. [68Ga]Ga-PSMA-11 SUVmax and FPQ showed predictive power regarding progression (AUCs: 0.89, 0.90). An introduced clinical score combining both further improved predictive performance (AUC: 0.94). Optimal cut-offs to foretell progression were: [68Ga]Ga-PSMA-11 SUVmax < 11.09 (88.2% sensitivity, 81.9% specificity), FPQ ≥ 0.92 (90.2% sensitivity, 78.7% specificity), clinical score ≥ 6/9 points (88.2% sensitivity, 87.5% specificity). At baseline, a low [68 Ga]Ga-PSMA-11 SUVmax and a high FPQ predict early lesional progression under RLT; [18F]FDG SUVmax does not. A score combining [68 Ga]Ga-PSMA-11 SUVmax and FPQ predicts early lesional progression even more effectively and might therefore be useful to quantitatively identify mismatch lesions.

Aberrant Super-Enhancer Landscape in Enzalutamide-Resistant Prostate Cancer Cells.

Background: Castration-resistant prostate cancer (CRPC), which has developed resistance to next-generation antiandrogens, such as enzalutamide (Enz), is a lethal disease. Furthermore, transcriptional regulation by super enhancers (SEs) is crucial for the growth and spread of prostate cancer, as well as drug resistance. The functions of SEs, a significant class of noncoding DNA cis-regulatory elements, have been the subject of numerous recent studies in the field of cancer research. Materials and Methods: The goal of this research was to identify SEs associated with Enz resistance in C4-2B cells using chromatin immunoprecipitation sequencing and cleavage under targets and tagmentation (CUT&Tag). Using HOMER analysis to predict protein/gene-binding motifs, we identified master transcription factors (TFs) that may bind to SE sites. Using small interfering RNA, WST-1 assays, and qRT-PCR, we then confirmed the associations between TFs of SEs and Enz resistance. Results: A total of 999 SEs were screened from C4-2B EnzR cells in total. Incorporating analysis with RNA-seq data revealed 41 SEs to be strongly associated with the promotion of Enz resistance. In addition, we finally predicted that master TFs bind to SE-binding regions. Subsequently, we selected zinc finger protein 467 (ZFP467) and SMAD family member 3 to confirm the functional connections of master TFs with Enz resistance through SEs (ZNF467). Conclusions: In this study, SMAD3 and ZNF467 were found to be closely related to Enz-resistant CRPC. Our research uncovered a sizable group of SEs linked to Enz resistance in prostate cancer, dissected the mechanisms underlying SE Enz resistance, and shed light on potential clinical uses for SEs.

CYB561 supports the neuroendocrine phenotype in castration-resistant prostate cancer.

Castration-resistant prostate cancer (CRPC) is associated with resistance to androgen deprivation therapy, and an increase in the population of neuroendocrine (NE) differentiated cells. It is hypothesized that NE differentiated cells secrete neuropeptides that support androgen-independent tumor growth and induce aggressiveness of adjacent proliferating tumor cells through a paracrine mechanism. The cytochrome b561 (CYB561) gene, which codes for a secretory vesicle transmembrane protein, is constitutively expressed in NE cells and highly expressed in CRPC. CYB561 is involved in the α-amidation-dependent activation of neuropeptides, and contributes to regulating iron metabolism which is often dysregulated in cancer. These findings led us to hypothesize that CYB561 may be a key player in the NE differentiation process that drives the progression and maintenance of the highly aggressive NE phenotype in CRPC. In our study, we found that CYB561 expression is upregulated in metastatic and NE prostate cancer (NEPC) tumors and cell lines compared to normal prostate epithelia, and that its expression is independent of androgen regulation. Knockdown of CYB561 in androgen-deprived LNCaP cells dampened NE differentiation potential and transdifferentiation-induced increase in iron levels. In NEPC PC-3 cells, depletion of CYB561 reduced the secretion of growth-promoting factors, lowered intracellular ferrous iron concentration, and mitigated the highly aggressive nature of these cells in complementary assays for cancer hallmarks. These findings demonstrate the role of CYB561 in facilitating transdifferentiation and maintenance of NE phenotype in CRPC through its involvement in neuropeptide biosynthesis and iron metabolism pathways.

Role of MicroRNA-21 in Prostate Cancer Progression and Metastasis: Molecular Mechanisms to Therapeutic Targets.

The role of noncoding RNA has made remarkable progress in understanding progression, metastasis, and metastatic castration-resistant prostate cancer (mCRPC). A better understanding of the miRNAs has enhanced our knowledge of their targeting mainly at the therapy level in solid tumors, such as prostate cancer (PCa). microRNAs (miRNAs) belong to a class of endogenous RNA that deficit encoded proteins. Therefore, the role of miRNAs has been well-coined in the progression and development of PCa. miR-21 has a dual nature in its work both as a tumor suppressor and oncogenic role, but most of the recent studies showed that miR-21 is a tumor promoter and also is involved in castration-resistant prostate cancer (CRPC). Upregulation of miR-21 suppresses programmed cell death and inducing metastasis and castration resistant in PCa. miR-21 is involved in the different stages, such as proliferation, angiogenesis, migration, and invasion, and plays an important role in the progression, metastasis, and advanced stages of PCa. Recently, various studies directly linked the role of high levels of miR-21 with a poor therapeutic response in the patient of PCa. In the present review, we have explained the molecular mechanisms/pathways of miR-21 in PCa progression, metastasis, and castration resistant and summarized the role of miR-21 in diagnosis and therapeutic levels in PCa. In addition, we have spotlighted the recent therapeutic strategies for targeting different stages of PCa.

Stem cell dynamics and cellular heterogeneity across lineage subtypes of castrate-resistant prostate cancer.

To resist lineage-dependent therapies such as androgen receptor inhibition, prostate luminal epithelial adenocarcinoma cells often adopt a stem-like state resulting in lineage plasticity and phenotypic heterogeneity. Castrate-resistant prostate adenocarcinoma can transition to neuroendocrine (NE) and occasionally to amphicrine, co-expressed luminal and NE, phenotypes. We developed castrate-resistant prostate cancer (CRPC) patient-derived organoid models that preserve heterogeneity of the originating tumor, including an amphicrine model displaying a range of luminal and NE phenotypes. To gain biological insight and to identify potential treatment targets within heterogeneous tumor cell populations, we assessed the lineage hierarchy and molecular characteristics of various CRPC tumor subpopulations. Transcriptionally similar stem/progenitor (St/Pr) cells were identified for all lineage populations. Lineage tracing in amphicrine CRPC showed that heterogeneity originated from distinct subclones of infrequent St/Pr cells that produced mainly quiescent differentiated amphicrine progeny. By contrast, adenocarcinoma CRPC progeny originated from St/Pr cells and self-renewing differentiated luminal cells. Neuroendocrine prostate cancer (NEPC) was composed almost exclusively of self-renewing St/Pr cells. Amphicrine subpopulations were enriched for secretory luminal, mesenchymal, and enzalutamide treatment persistent signatures that characterize clinical progression. Finally, the amphicrine St/Pr subpopulation was specifically depleted with an AURKA inhibitor, which blocked tumor growth. These data illuminate distinct stem cell (SC) characteristics for subtype-specific CRPC in addition to demonstrating a context for targeting differentiation-competent prostate SCs.

PDIA2 has a dual function in promoting androgen deprivation therapy induced venous thrombosis events and castrate resistant prostate cancer progression.

Androgen deprivation therapy (ADT) is the first line of treatment for metastatic prostate cancer (PCa) that effectively delays the tumor progression. However, it also increases the risk of venous thrombosis event (VTE) in patients, a leading cause of mortality. How a pro-thrombotic cascade is induced by ADT remains poorly understood. Here, we report that protein disulfide isomerase A2 (PDIA2) is upregulated in PCa cells to promote VTE formation and enhance PCa cells resistant to ADT. Using various in vitro and in vivo models, we demonstrated a dual function of PDIA2 that enhances tumor-mediated pro-coagulation activity via tumor-derived extracellular vehicles (EVs). It also stimulates PCa cell proliferation, colony formation, and xenograft growth androgen-independently. Mechanistically, PDIA2 activates the tissue factor (TF) on EVs through its isomerase activity, which subsequently triggers a pro-thrombotic cascade in the blood. Additionally, TF-containing EVs can activate the Src kinase inside PCa cells to enhance the AR signaling ligand independently. Androgen deprivation does not alter PDIA2 expression in PCa cells but enhances PDIA2 translocation to the cell membrane and EVs via suppressing the clathrin-dependent endocytic process. Co-recruitment of AR and FOXA1 to the PDIA2 promoter is required for PDIA2 transcription under androgen-deprived conditions. Importantly, blocking PDIA2 isomerase activity suppresses the pro-coagulation activity of patient plasma, PCa cell, and xenograft samples as well as castrate-resistant PCa xenograft growth. These results demonstrate that PDIA2 promotes VTE and tumor progression via activating TF from tumor-derived EVs. They rationalize pharmacological inhibition of PDIA2 to suppress ADT-induced VTE and castrate-resistant tumor progression.

Development and Characterisation of a New Patient-Derived Xenograft Model of AR-Negative Metastatic Castration-Resistant Prostate Cancer.

As the treatment landscape for prostate cancer gradually evolves, the frequency of treatment-induced neuroendocrine prostate cancer (NEPC) and double-negative prostate cancer (DNPC) that is deficient for androgen receptor (AR) and neuroendocrine (NE) markers has increased. These prostate cancer subtypes are typically refractory to AR-directed therapies and exhibit poor clinical outcomes. Only a small range of NEPC/DNPC models exist, limiting our molecular understanding of this disease and hindering our ability to perform preclinical trials exploring novel therapies to treat NEPC/DNPC that are urgently needed in the clinic. Here, we report the development of the CU-PC01 PDX model that represents AR-negative mCRPC with PTEN/RB/PSMA loss and CTNN1B/TP53/BRCA2 genetic variants. The CU-PC01 model lacks classic NE markers, with only focal and/or weak expression of chromogranin A, INSM1 and CD56. Collectively, these findings are most consistent with a DNPC phenotype. Ex vivo and in vivo preclinical studies revealed that CU-PC01 PDX tumours are resistant to mCRPC standard-of-care treatments enzalutamide and docetaxel, mirroring the donor patient's treatment response. Furthermore, short-term CU-PC01 tumour explant cultures indicate this model is initially sensitive to PARP inhibition with olaparib. Thus, the CU-PC01 PDX model provides a valuable opportunity to study AR-negative mCRPC biology and to discover new treatment avenues for this hard-to-treat disease.

A resource-based mechanistic framework for castration-resistant prostate cancer (CRPC).

Cancer therapy often leads to the selective elimination of drug-sensitive cells from the tumour. This can favour the growth of cells resistant to the therapeutic agent, ultimately causing a tumour relapse. Castration-resistant prostate cancer (CRPC) is a well-characterised instance of this phenomenon. In CRPC, after systemic androgen deprivation therapy (ADT), a subset of drug-resistant cancer cells autonomously produce testosterone, thus enabling tumour regrowth. A previous theoretical study has shown that such a tumour relapse can be delayed by inhibiting the growth of drug-resistant cells using biotic competition from drug-sensitive cells. In this context, the centrality of resource dynamics to intra-tumour competition in the CRPC system indicates clear scope for the construction of theoretical models that can explicitly incorporate the underlying mechanisms of tumour ecology. In the current study, we use a modified logistic framework to model cell-cell interactions in terms of the production and consumption of resources. Our results show that steady state composition of CRPC can be understood as a composite function of the availability and utilisation efficiency of two resources-oxygen and testosterone. In particular, we show that the effect of changing resource availability or use efficiency is conditioned by their general abundance regimes. Testosterone typically functions in trace amounts and thus affects steady state behaviour of the CRPC system differently from oxygen, which is usually available at higher levels. Our data thus indicate that explicit consideration of resource dynamics can produce novel and useful mechanistic understanding of CRPC. Furthermore, such a modelling approach also incorporates variables into the system's description that can be directly measured in a clinical context. This is therefore a promising avenue of research in cancer ecology that could lead to therapeutic approaches that are more clearly rooted in the biology of CRPC.

Role of extracellular vesicles in castration-resistant prostate cancer.

Prostate cancer (PCa) is a common health threat to men worldwide, and castration-resistant PCa (CRPC) is the leading cause of PCa-related deaths. Extracellular vesicles (EVs) are lipid bilayer compartments secreted by living cells that are important mediators of intercellular communication. EVs regulate the biological processes of recipient cells by transmitting heterogeneous cargoes, contributing to CRPC occurrence, progression, and drug resistance. These EVs originate not only from malignant cells, but also from various cell types within the tumor microenvironment. EVs are widely dispersed throughout diverse biological fluids and are attractive biomarkers derived from noninvasive liquid biopsy techniques. EV quantities and cargoes have been tested as potential biomarkers for CRPC diagnosis, progression, drug resistance, and prognosis; however, technical barriers to their clinical application continue to exist. Furthermore, exogenous EVs may provide tools for new therapies for CRPC. This review summarizes the current evidence on the role of EVs in CRPC.

Microwave hyperthermia enhances radiosensitization by decreasing DNA repair efficiency and inducing oxidative stress in PC3 prostatic adenocarcinoma cells.

PURPOSE: Radiotherapy (RT) is the primary treatment for prostate cancer (PCa); however, the emergence of castration-resistant prostate cancer (CRPC) often leads to treatment failure and cancer-related deaths. In this study, we aimed to explore the use of microwave hyperthermia (MW-HT) to sensitize PCa to RT and investigate the underlying molecular mechanisms. METHODS: We developed a dedicated MW-HT heating setup, created an in vitro and in vivo MW-HT + RT treatment model for CRPC. We evaluated PC3 cell proliferation using CCK-8, colony experiments, DAPI staining, comet assay and ROS detection method. We also monitored nude mouse models of PCa during treatment, measured tumor weight, and calculated the tumor inhibition rate. Western blotting was used to detect DNA damage repair protein expression in PC3 cells and transplanted tumors. RESULTS: Compared to control, PC3 cell survival and clone formation rates decreased in RT + MW-HT group, demonstrating significant increase in apoptosis, ROS levels, and DNA damage. Lower tumor volumes and weights were observed in treatment groups. Ki-67 expression level was reduced in all treatment groups, with significant decrease in RT + MW-HT groups. The most significant apoptosis induction was confirmed in RT + MW-HT group by TUNEL staining. Protein expression levels of DNA-PKcs, ATM, ATR, and P53/P21 signaling pathways significantly decreased in RT + MW-HT groups. CONCLUSION: MW-HT + RT treatment significantly inhibited DNA damage repair by downregulating DNA-PKcs, ATM, ATR, and P53/P21 signaling pathways, leading to increased ROS levels, aggravate DNA damage, apoptosis, and necrosis in PC3 cells, a well-established model of CRPC.

Blocking lipid synthesis induces DNA damage in prostate cancer and increases cell death caused by PARP inhibition.

Androgen deprivation therapy (ADT) is the primary treatment for prostate cancer; however, resistance to ADT invariably develops, leading to castration-resistant prostate cancer (CRPC). Prostate cancer progression is marked by increased de novo synthesis of fatty acids due to overexpression of fatty acid synthase (FASN), making this enzyme a therapeutic target for prostate cancer. Inhibition of FASN results in increased intracellular amounts of ceramides and sphingomyelin, leading to DNA damage through the formation of DNA double-strand breaks and cell death. We found that combining a FASNi with the poly-ADP ribose polymerase (PARP) inhibitor olaparib, which induces cell death by blocking DNA damage repair, resulted in a more pronounced reduction in cell growth than that caused by either drug alone. Human CRPC organoids treated with a combination of PARP and FASNi were smaller, had decreased cell proliferation, and showed increased apoptosis and necrosis. Together, these data indicate that targeting FASN increases the therapeutic efficacy of PARP inhibitors by impairing DNA damage repair, suggesting that combination therapies should be explored for CRPC.

Predicting abiraterone efficacy in advanced prostate cancer: Insights from marker of proliferation Ki67.

BACKGROUND: KI67 is a well-known biomarker reflecting cell proliferation. We aim to elucidate the predictive role of KI67 in the efficacy of abiraterone for patients with advanced prostate cancer (PCa). METHODS: Clinicopathological data of 152 men with metastatic PCa, who received abiraterone therapy were retrospectively collected. The KI67 positivity was examined by immunohistochemistry using the prostate biopsy specimen. The predictive value of KI67 on the therapeutic efficacy of abiraterone was explored using Kaplan-Meier curve and Cox regression analysis. The endpoints included prostate-specific antigen (PSA) progression-free survival (PSA-PFS), radiographic PFS (rPFS), and overall survival (OS). RESULTS: In total, 85/152 (55.9%) and 67/152 (44.1%) cases, respectively, received abiraterone at metastatic hormone-sensitive (mHSPC) and castration-resistant PCa (mCRPC) stage. The median KI67 positivity was 20% (interquartile range: 10%-30%). Overall, KI67 rate was not correlated with PSA response. Notably, an elevated KI67-positive rate strongly correlated with unfavorable abiraterone efficacy, with KI67 ≥ 30% and KI67 ≥ 20% identified as the optimal cutoffs for prognosis differentiation in mHSPC (median PSA-PFS: 11.43 Mo vs. 26.43 Mo, p < 0.001; median rPFS: 16.63 Mo vs. 31.90 Mo, p = 0.003; median OS: 21.77 Mo vs. not reach, p = 0.005) and mCRPC (median PSA-PFS: 7.17 Mo vs. 12.20 Mo, p = 0.029; median rPFS: 11.67 Mo vs. 16.47 Mo, p = 0.012; median OS: 21.67 Mo vs. not reach, p = 0.073) patients, respectively. Multivariate analysis supported the independent predictive value of KI67 on abiraterone efficacy. In subgroup analysis, an elevated KI67 expression was consistently associated with unfavorable outcomes in the majority of subgroups. Furthermore, data from another cohort of 79 PCa patients with RNA information showed that those with KI67 RNA levels above the median had a significantly shorter OS than those below the median (17.71 vs. 30.72 Mo, p = 0.035). CONCLUSIONS: This study highlights KI67 positivity in prostate biopsy as a strong predictor of abiraterone efficacy in advanced PCa. These insights will assist clinicians in anticipating clinical outcomes and refining treatment decisions for PCa patients.

Co-targeting BET, CBP, and p300 inhibits neuroendocrine signalling in androgen receptor-null prostate cancer.

There are diverse phenotypes of castration-resistant prostate cancer, including neuroendocrine disease, that vary in their sensitivity to drug treatment. The efficacy of BET and CBP/p300 inhibitors in prostate cancer is attributed, at least in part, to their ability to decrease androgen receptor (AR) signalling. However, the activity of BET and CBP/p300 inhibitors in prostate cancers that lack the AR is unclear. In this study, we showed that BRD4, CBP, and p300 were co-expressed in AR-positive and AR-null prostate cancer. A combined inhibitor of these three proteins, NEO2734, reduced the growth of both AR-positive and AR-null organoids, as measured by changes in viability, size, and composition. NEO2734 treatment caused consistent transcriptional downregulation of cell cycle pathways. In neuroendocrine models, NEO2734 treatment reduced ASCL1 levels and other neuroendocrine markers, and reduced tumour growth in vivo. Collectively, these results show that epigenome-targeted inhibitors cause decreased growth and phenotype-dependent disruption of lineage regulators in neuroendocrine prostate cancer, warranting further development of compounds with this activity in the clinic. © 2024 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

Co-targeting SKP2 and KDM5B inhibits prostate cancer progression by abrogating AKT signaling with induction of senescence and apoptosis.

BACKGROUND: Prostate cancer (PCa) is the second-leading cause of cancer mortalities in the United States and is the most commonly diagnosed malignancy in men. While androgen deprivation therapy (ADT) is the first-line treatment option to initial responses, most PCa patients invariably develop castration-resistant PCa (CRPC). Therefore, novel and effective treatment strategies are needed. The goal of this study was to evaluate the anticancer effects of the combination of two small molecule inhibitors, SZL-P1-41 (SKP2 inhibitor) and PBIT (KDM5B inhibitor), on PCa suppression and to delineate the underlying molecular mechanisms. METHODS: Human CRPC cell lines, C4-2B and PC3 cells, were treated with small molecular inhibitors alone or in combination, to assess effects on cell proliferation, migration, senescence, and apoptosis. RESULTS: SKP2 and KDM5B showed an inverse regulation at the translational level in PCa cells. Cells deficient in SKP2 showed an increase in KDM5B protein level, compared to that in cells expressing SKP2. By contrast, cells deficient in KDM5B showed an increase in SKP2 protein level, compared to that in cells with KDM5B intact. The stability of SKP2 protein was prolonged in KDM5B depleted cells as measured by cycloheximide chase assay. Cells deficient in KDM5B were more vulnerable to SKP2 inhibition, showing a twofold greater reduction in proliferation compared to cells with KDM5B intact (p < 0.05). More importantly, combined inhibition of KDM5B and SKP2 significantly decreased proliferation and migration of PCa cells as compared to untreated controls (p < 0.005). Mechanistically, combined inhibition of KDM5B and SKP2 in PCa cells abrogated AKT activation, resulting in an induction of both cellular senescence and apoptosis, which was measured via Western blot analysis and senescence-associated ß-galactosidase (SA-ß-Gal) staining. CONCLUSIONS: Combined inhibition of KDM5B and SKP2 was more effective at inhibiting proliferation and migration of CRPC cells, and this regimen would be an ideal therapeutic approach of controlling CRPC malignancy.

AR-V7 expression facilitates accelerated G2/M phase transition in castration-resistant prostate cancer.

The emergence of AR-V7, a truncated isoform of AR upon androgen deprivation therapy treatment, leads to the development of castration resistant prostate cancer (CRPC). Understanding mechanisms that regulate AR-V7 expression is critical for developing newer therapeutic strategies. In this study, we have investigated the regulation of AR-V7 during cell cycle and identified a distinct pattern of periodic fluctuation, peaking during G2/M phase. This fluctuation correlates with the expression of Cdc-2 like kinase 1 (CLK1) and phosphorylated serine/arginine-rich splicing factor 1 (p-SRSF1) during these phases, pointing towards their role in AR-V7 generation. Functional assays reveal that CLK1 knockdown prolongs the S phase, leading to altered cell cycle distribution and increased accumulation of AR-V7 and pSRSF1 in G1/S phase. Conversely, CLK1 overexpression rescues AR-V7 and p-SRSF1 levels in the G2/M phase, consistent with observed cell cycle alterations upon AR-V7 knockdown and overexpression in CRPC cells. Furthermore, overexpression of kinase-deficient CLK1 mutant leads to diminished AR-V7 levels during G2/M, underlining the essential contribution of CLK1's kinase activity in modulating AR-V7 expression. Collectively, our findings, for the first time, show periodic regulation of AR-V7 expression, its effect on cell cycle progression and the critical role of CLK1-pSRSF1 axis in modulating AR-V7 expression throughout the cell cycle.