Preclinical and Clinical Research Models of Prostate Cancer: A Brief Overview

A novel lncRNA FLJ promotes castration resistance in prostate cancer through AR mediated autophagy

BACKGROUND

Progression to castration resistance is the leading cause of death in prostate cancer patients. Long non-coding RNAs (lncRNAs) have recently become a focal point in the regulation of cancer development. However, few lncRNAs associated with castration-resistant prostate cancer (CRPC) have been reported.

METHODS

Firstly, we explore the CRPC associated lncRNAs by RNA sequencing and validated using quantitative polymerase chain reaction (qRT-PCR) and RNA fluorescence in situ hybridization (RNA-FISH). The clinical significance of FLJ was evaluated in a collected cancer cohort. Functional loss assays were performed to assess the effects of FLJ on CRPC cells both in vitro and in vivo. The regulatory mechanism of FLJ was investigated using immunohistochemistry (IHC), qRT-PCR, dual-luciferase reporter assays, and chromatin immunoprecipitation (ChIP) assays.

RESULTS

FLJ is highly expressed in CRPC and is associated with higher stages and Gleason scores in prostate cancer. FLJ is strongly positively correlated with androgen receptor (AR), which acts as a transcription factor and directly binds to the FLJ promoter region to enhance its transcription. Knockdown of FLJ inhibits CRPC cell proliferation and increases sensitivity to castration and enzalutamide (ENZA) in vitro. Mechanistically, FLJ promotes castration resistance in prostate cancer cells by inhibiting AR nuclear import and cytoplasmic protein degradation, thereby activating the androgen-independent AR signaling pathway. Importantly, in vivo experiments showed that FLJ knockdown inhibited tumor growth and enhanced the therapeutic effect of ENZA.

CONCLUSIONS

This study identifies a novel regulatory mechanism by which lncRNA FLJ promotes CRPC progression. Sustained AR activation in CRPC acts as a transcription factor to upregulate FLJ expression. FLJ circumvents the traditional androgen-dependent survival mechanism by inhibiting AR nuclear entry and cytoplasmic protein degradation, thereby activating the AR signaling pathway. Targeting the FLJ-AR signaling axis may represent a novel therapeutic strategy for patients with castration-resistant prostate cancer.

Altered expression and localization of nuclear envelope proteins in a prostate cancer cell system

BACKGROUND

The nuclear envelope (NE), which is composed of the outer and inner nuclear membranes, the nuclear pore complex and the nuclear lamina, regulates a plethora of cellular processes, including those that restrict cancer development (genomic stability, cell cycle regulation, and cell migration). Thus, impaired NE is functionally related to tumorigenesis, and monitoring of NE alterations is used to diagnose cancer. However, the chronology of NE changes occurring during cancer evolution and the connection between them remained to be precisely defined, due to the lack of appropriate cell models.

METHODS

The expression and subcellular localization of NE proteins (lamins A/C and B1 and the inner nuclear membrane proteins emerin and β-dystroglycan [β-DG]) during prostate cancer progression were analyzed, using confocal microscopy and western blot assays, and a prostate cancer cell system comprising RWPE-1 epithelial prostate cells and several prostate cancer cell lines with different invasiveness.

RESULTS

Deformed nuclei and the mislocalization and low expression of lamin A/C, lamin B1, and emerin became more prominent as the invasiveness of the prostate cancer lines increased. Suppression of lamin A/C expression was an early event during prostate cancer evolution, while a more extensive deregulation of NE proteins, including β-DG, occurred in metastatic prostate cells.

CONCLUSIONS

The RWPE-1 cell line-based system was found to be suitable for the correlation of NE impairment with prostate cancer invasiveness and determination of the chronology of NE alterations during prostate carcinogenesis. Further study of this cell system would help to identify biomarkers for prostate cancer prognosis and diagnosis.

Reproducible preclinical models of androgen receptor driven human prostate cancer bone metastasis

BACKGROUND

Preclinical models recapitulating the metastatic phenotypes are essential for developing the next-generation therapies for metastatic prostate cancer (mPC). We aimed to establish a cohort of clinically relevant mPC models, particularly androgen receptor positive (AR+) bone metastasis models, from LuCaP patient-derived xenografts (PDX) that reflect the heterogeneity and complexity of mPC.

METHODS

PDX tumors were dissociated into single cells, modified to express luciferase, and were inoculated into NSG mice via intracardiac injection. The progression of metastases was monitored by bioluminescent imaging. Histological phenotypes of metastases were characterized by immunohistochemistry and immunofluorescence staining. Castration responses were further investigated in two AR-positive models.

RESULTS

Our PDX-derived metastasis (PDM) model collection comprises three AR+ adenocarcinomas (ARPC) and one AR- neuroendocrine carcinoma (NEPC). All ARPC models developed bone metastases with either an osteoblastic, osteolytic, or mixed phenotype, while the NEPC model mainly developed brain metastasis. Different mechanisms of castration resistance were observed in two AR+ PDM models with distinct genotypes, such as combined loss of TP53 and RB1 in one model and expression of AR splice variant 7 (AR-V7) expression in another model. Intriguingly, the castration-resistant tumors displayed inter- and intra-tumor as well as organ-specific heterogeneity in lineage specification.

CONCLUSION

Genetically diverse PDM models provide a clinically relevant system for biomarker identification and personalized medicine in metastatic castration-resistant prostate cancer.

Organoids: An Emerging Precision Medicine Model for Prostate Cancer Research

Prostate cancer (PCa) has been known as the most prevalent cancer disease and the second leading cause of cancer mortality in men almost all over the globe. There is an urgent need for establishment of PCa models that can recapitulate the progress of genomic landscapes and molecular alterations during development and progression of this disease. Notably, several organoid models have been developed for assessing the complex interaction between PCa and its surrounding microenvironment. In recent years, PCa organoids have been emerged as powerful in vitro 3D model systems that recapitulate the molecular features (such as genomic/epigenomic changes and tumor microenvironment) of PCa metastatic tumors. In addition, application of organoid technology in mechanistic studies (i.e., for understanding cellular/subcellular and molecular alterations) and translational medicine has been recognized as a promising approach for facilitating the development of potential biomarkers and novel therapeutic strategies. In this review, we summarize the application of PCa organoids in the high-throughput screening and establishment of relevant xenografts for developing novel therapeutics for metastatic, castration resistant, and neuroendocrine PCa. These organoid-based studies are expected to expand our knowledge from basic research to clinical applications for PCa diseases. Furthermore, we also highlight the optimization of PCa cultures and establishment of promising 3D organoid models for in vitro and in vivo investigations, ultimately facilitating mechanistic studies and development of novel clinical diagnosis/prognosis and therapies for PCa.