Survivin mRNA-circulating tumor cells are associated with prostate cancer metastasis

Novel small-molecule LG1836 inhibits the in vivo growth of castration-resistant prostate cancer

BACKGROUND

Androgen deprivation therapy (ADT) is the mainstay of treatment for castration-resistant prostate cancer (CRPC). Unfortunately, although ADT initially prolongs survival, most patients relapse and develop resistance. Clinical failure of these treatments in CRPC highlights the urgent need to develop novel strategies to more effectively block androgen receptor (AR) signaling and target other oncogenic factors responsible for ADT resistance.

METHODS

We developed a small-molecule compound LG1836 and investigated the in vitro and in vivo activity of LG1836 against CRPC in cellular and animal models.

RESULTS

LG1836 exhibits potent in vitro cytotoxicity in CRPC cells. Mechanistic studies demonstrated that LG1836 inhibits the expression of AR and AR variant 7, partially mediated via proteasome-dependent protein degradation. LG1836 also suppresses survivin expression and effectively induces apoptosis in CRPC cells. Significantly, as a single agent, LG1836 is therapeutically efficacious in suppressing the in vivo growth of CRPC in the subcutaneous and intraosseous models and extends the survival of tumor-bearing mice.

CONCLUSIONS

These preclinical studies indicate that LG1836 is a promising lead compound for the treatment of CRPC.

JAB1/COPS5 is a putative oncogene that controls critical oncoproteins deregulated in prostate cancer

Recent evidence support that the c-Jun activation domain-binding protein 1 (JAB1)/COPS5 has an oncogenic function in various tissues. We show that JAB1 amplification in human prostate cancer (PCa) correlates with reduced overall survival and disease-free progression. Immunohistochemical staining shows enhanced expression of JAB1 in the cytoplasmic compartment of PCa cells compared to the normal prostate epithelium, indicating the activity/function of JAB1 is altered in PCa. To test the function of JAB1 in PCa, we efficiently silenced JAB1 expression using four unique shRNAs in three PCa cell lines (LNCaP, C4-2, and PC-3) and an immortalized prostate epithelial cell line, RWPE-1. Our data clearly show that silencing JAB1 robustly suppresses the growth of PCa cells, but not RWPE-1 cells, suggesting that PCa cells become addicted to JAB1. To study the potential mechanism by which JAB1 controls PCa growth, we profiled gene expression changes by whole transcriptome microarray analysis of C4-2 cells silenced for JAB1 using a pool of 3 shRNAs compared to scrambled shRNA control. We identified 1268 gene changes ≥1.5 fold by silencing JAB1 in C4-2. Western blot confirmation and bioinformatics pathway analyses support that PCa cells become addicted to JAB1 through controlling the following signaling pathways: cell cycle, p53 signaling, DNA replication, TGF-β/BMP, MAPK, TNF, and steroid hormone biosynthesis. We propose that UGT2B28, UGT2B10, UGT2B11, Skp2, EZH2, MDM2, BIRC5 (Survivin), UBE2C, and Smads 1/5/8, which are all associated with the abovementioned key oncogenic pathways, may play critical roles in the putative oncogenic function of JAB1 in PCa.

Discovering the miR-26a-5p Targetome in Prostate Cancer Cells

Purpose. miR-26a-5p is a tumor suppressor (TS) miRNA often downregulated in several tumor tissues and tumor cell lines. In this work, we performed the re-expression of the miR-26a-5p in DU-145 prostate cancer cells to collect genes interacting with miR-26a-5p and analyzed their integration in the tumorigenesis related pathways.

Methods. The transfection of DU-145 prostate cancer cells with miR-26a-5p was done using nucleofection. The biological effects induced by miR-26a-5p re-expression were detected with routine assays for cell proliferation, cell cycle, survival, apoptosis and cell migration. The miRNA pull out technique was used to collect and next generation sequencing to identify the complete repertoire of the miR-26a-5p targets (miR-26a-5p/targetome). TargetScan 7, PITA and RNA22 were used to find the predicted miR-26a-5p targets in the miR-26a-5p/targetome. Gene set enrichment analysis were used to integrate target genes in KEGG pathways and Protein-Protein Interaction networks (PPINs) and modules were built.

Results. miR-26a-5p exerted an anti-proliferative effect acting at several levels, by decreasing survival and migration and inducing both cell cycle block and apoptosis. The analysis of the miR-26a-5p/targetome showed that 1423 (1352 coding and 71 non-coding) transcripts interacted with miR-26a-5p. Filtering the miR-26a-5p/targetome with prediction algorithms, 628 out of 1353 transcripts were miR-26a-5p predicted targets and 73 of them were already validated miR-26a-5p targets. Finally, miR-26a-5p targets were involved in 22 KEGG pathways and 20 significant protein-protein interaction modules

Conclusion. The TS-miR-26a-5p/targetome is a platform that shows both unknown and known miRNA/target interactions thus offering the possibility to validate genes and discover pathways in which these genes could be involved.

Circulating tumor cells in prostate cancer: Precision diagnosis and therapy

The primary cause of tumor-associated mortality in prostate cancer (PCa) remains distant metastasis. The dissemination of tumor cells from the primary tumor to distant sites through the bloodstream cannot be detected early by standard imaging methods. Circulating tumor cells (CTCs) represent an effective prognostic and predictive biomarker, which are able to monitor efficacy of adjuvant therapies, detect early development of metastases, and finally, assess therapeutic responses of advanced disease earlier than traditional diagnostic methods. In addition, since repeated tissue biopsies are invasive, costly and not always feasible, the assessment of tumor characteristics on CTCs, by a peripheral blood sample as a liquid biopsy, represents an attractive opportunity. The implementation of molecular and genomic characterization of CTCs may contribute to improve the treatment selection and thus, to move toward more precise diagnosis and therapy in PCa. The present study summarizes the current advances in CTC enrichment and detection strategies and reviews how CTCs may contribute to significant insights in the metastatic process, as well as how they may be utilized in clinical application in PCa. Although it is proposed that CTCs may offer insights into the prognosis and management of PCa, there are a number of challenges in the study of circulating tumor cells, and their clinical utility remains under investigation.

Knockdown of PARP6 or survivin promotes cell apoptosis and inhibits cell invasion of colorectal adenocarcinoma cells

Colorectal adenocarcinoma is the third most common cancer worldwide. PARP6, a novel member of the poly(ADP-ribose) polymerases (PARPs) and survivin, a member of the family of inhibitor of apoptosis (IAP) proteins are associated with a poor prognosis in various types of cancers. However, limited evidence exists regarding the interaction between PARP6 and survivin in colorectal adenocarcinoma. In the present study, we used the paired samples of 20 patients with colorectal adenocarcinoma to detect the expression of PARP6 and survivin in both tumor and adjacent normal colorectal mucosa. Their interaction and roles in cell viability, cell cycle, cell apoptosis and cell invasion were further investigated. Our results showed that both PARP6 and survivin exhibited higher expression in colorectal adenocarcinoma tissues and SW620 cells when compared with levels in adjacent non-tumor tissues and a normal colon cell line FHC. Co-immunoprecipitation assay showed that a significant correlation existed between PARP6 and survivin. We also showed that sole treatment of PARP6 siRNA or survivin siRNA partially inhibited the cell survival and invasion, induced cell G0/G1 arrest, and cell apoptosis at the early and late stages. The combined treatment of PARP6 siRNA and survivin siRNA suppressed the cell survival and cell invasion, further induced cell cycle phase G0/G1 arrest, and cell apoptosis at the early and late stages. Taken together, knockdown of PARP6 or survivin promotes cell apoptosis and inhibits the cell invasion of colorectal adenocarcinoma cells. A significant correlation exists between PARP6 and survivin, and both are promising targets for the development of new strategies for the diagnosis and treatment of advanced or metastatic colorectal adenocarcinoma.