Scaffold protein MAPK8IP2 expression is a robust prognostic factor in prostate cancer associated with AR signaling activity.

Mitogen-activated protein kinase-8-interacting protein 2 (MAPK8IP2) is a scaffold protein that modulates MAPK signal cascades. Although MAPK pathways were heavily implicated in prostate cancer progression, the regulation of MAPK8IP2 expression in prostate cancer is not yet reported. We assessed MAPK8IP2 gene expression in prostate cancer related to disease progression and patient survival outcomes. MAPK8IP2 expression was analyzed using multiple genome-wide gene expression datasets derived from The Cancer Genome Atlas (TCGA) RNA-sequence project and complementary DNA (cDNA) microarrays. Multivariable Cox regressions and log-rank tests were used to analyze the overall survival outcome and progression-free interval. MAPK8IP2 protein expression was evaluated using the immunohistochemistry approach. The quantitative PCR and Western blot methods analyzed androgen-stimulated MAPK8IP2 expression in LNCaP cells. In primary prostate cancer tissues, MAPK8IP2 mRNA expression levels were significantly higher than those in the case-matched benign prostatic tissues. Increased MAPK8IP2 expression was strongly correlated with late tumor stages, lymph node invasion, residual tumors after surgery, higher Gleason scores, and preoperational serum prostate-specific antigen (PSA) levels. MAPK8IP2 upregulation was significantly associated with worse overall survival outcomes and progression-free intervals. In castration-resistant prostate cancers, MAPK8IP2 expression strongly correlated with androgen receptor (AR) signaling activity. In cell culture-based experiments, MAPK8IP2 expression was stimulated by androgens in AR-positive prostate cancer cells. However, MAPK8IP2 expression was blocked by AR antagonists only in androgen-sensitive LNCaP but not castration-resistant C4-2B and 22RV1 cells. These results indicate that MAPK8IP2 is a robust prognostic factor and therapeutic biomarker for prostate cancer. The potential role of MAPK8IP2 in the castration-resistant progression is under further investigation.

[Glycogen synthase kinase3 and prostate cancer: An update].

Glycogen synthase kinase3 (GSK3α and GSK3ß) are serine/threonine protein kinases acting on numerous substrates and involved in the regulation of various cellular functions such as their proliferation, survival, glycogen metabolism, and autophagy. Accumulating evidence indicates that the expression of GSK3α is increased mainly in androgendependent while that of GSK3ß in androgenindependent prostate cancer, and that GSK3ß is also involved in the regulation of the transactivation of the androgen receptor (AR) and growth of prostate cancer. Animal experiments have proved that some GSK3 inhibitors, such as lithium, can significantly suppress tumor growth in different animal models of prostate cancer. The GSK3 inhibitor is promising to be an important agent for the clinical management of prostate cancer.

[PI3K/p110ß-specific inhibitors in castration-resistant prostate cancer].

Advanced prostate cancer, especially at the castration-resistant stage, remains incurable clinically and, therefore, urgently requires new therapeutics for the patients. PI3K is a family of critical cell signal transduction molecules and their over-activation is an important factor in cancer development and progression. It has been demonstrated that class IA PI3K p110 is drastically overexpressed in prostate cancer and involved in androgen receptor-mediated gene expression and castration-resistant progression and regarded as a potential therapeutic target for prostate cancer. Several p110-specific inhibitors have been reported recently and two of them, GSK2636771 and AZD8186, are being tested in clinical trials.

[Updated roles of adrenergic receptors in prostate cancer].

Adrenergic receptors are members of the G-protein coupled receptor superfamily. Recent studies revealed that these adrenergic receptors are playing an important role in the growth and metastasis of prostate cancer cells. The expression of adrenergic receptors rises significantly in prostate cancer cells and tissues. Agonists of these receptors promote the growth and mobility of prostate cancer cells, while antagonists may suppress their proliferation, trigger their apoptosis, and inhibit their metastasis. Clinically, receptor antagonists can significantly reduce the risk of prostate cancer and improve its prognosis after androgen depravation therapy. This article presents an overview on the roles of adrenergic receptors in prostate cancer.

[Both CK2 catalytic subunits involves in androgen receptor signaling in prostate cancer cells].

OBJECTIVE: To explore the roles of different casein kinase 2 (CK2) catalytic subunits in androgen receptor (AR) signaling in prostate cancer cell lines. METHODS: Prostate cancer cell lines were maintained.Immunofluorescent staining was performed to determine AR nuclear translocation in PC-3/AR cells with R1881 pretreatment and luciferase gene reporter assay used to determine AR transactivation in LNCaP cells. And reverse transcription-polymerase chain reaction (RT-PCR) was employed to evaluate the mRNA level of prostate-specific antigen (PSA). RESULTS: R1881-induced AR nuclear localization was reduced significantly (P < 0.01).R1881-stimulated ARE-LUC reporter activity in LNCaP cells decreased with reduced level of PSA mRNA, an AR endogenous target (P < 0.05). To confirm the target specificity, the gene-specific siRNAs were used for both CK2α and CK2α' subunits. The results of ARE-LUC assay (38.5 vs 31.4) suggested that both CK2 catalytic subunits were involved in androgen-stimulated AR nuclear translocation and AR-mediated gene expression in prostate cancer cells. CONCLUSION: Both CK2 catalytic subunits are involved in androgen receptor signaling of prostate cancer cells.

[Research progresses on the role of cell autophagy in cancer].

Autophagy is a vital basic phenomenon that widely exists in eukaryotic cells. As one type of programmed cell death, autophagy has gained much more attention in the past several years. Recent evidences suggest that the alterations in autophagy are associated with the genesis and development of cancers. It can affect cell apoptosis, angiogenesis and treatment of tumor. This article focuses on recent progresses of autophagy research related to human cancers.

[Association of mating type switching/sucrose non-fermenting complex with prostate cancer].

ATP-dependent chromatin remodeling by the mating type switching/sucrose non-fermenting (SWI/SNF) complex is a basic biological event in the body, which is required for all the key processes involved in DNA metabolism such as gene expression, DNA replication, repair, chromosomal recombination and mitosis. In the past few years, increasing evidence supports a crucial role of this complex in prostate cancer development and progression via multiple ways, such as cell cycle regulation, androgen receptor pathway and DNA methylation. The present paper briefly reviews the recent studies on the association between the SWI/SNF complex and prostate cancer.

Dual androgen-response elements mediate androgen regulation of MMP-2 expression in prostate cancer cells.

AIM: To characterize the matrix metalloproteinases (MMP)-2 promoter and to identify androgen response elements (AREs) involved in androgen-induced MMP-2 expression. METHODS: MMP-2 mRNA levels was determined by reverse transcription-polymerase chain reaction (RT-PCR). MMP-2 promoter-driven luciferase assays were used to determine the fragments responsible for androgen-induced activity. Chromatin-immunoprecipitation assay and electrophoretic mobility shift assays (EMSA) were used to verify the identified AREs in the MMP-2 promoter. RESULTS: Androgen significantly induced MMP-2 expression at the mRNA level, which was blocked by the androgen antagonist bicalutamide. Deletion of a region encompassing base pairs -1591 to -1259 (relative to the start codon) of the MMP-2 promoter led to a significant loss of androgen-induced reporter activity. Additional deletion of the 5'-region up to -562 bp further reduced the androgen-induced MMP-2 promoter activity. Sequence analysis of these two regions revealed two putative ARE motifs. Introducing mutations in the putative ARE motifs by site-directed mutagenesis approach resulted in a dramatic loss of androgen-induced MMP-2 promoter activity, indicating that the putative ARE motifs are required for androgen-stimulated MMP-2 expression. Most importantly, the androgen receptor (AR) interacted with both motif-containing promoter regions in vivo in a chromatin immunoprecipitation assay after androgen treatment. Furthermore, the AR specifically bound to the wild-type but not mutated ARE motifs-containing probes in an in vitro EMSA assay. CONCLUSION: Two ARE motifs were identified to be responsible for androgen-induced MMP-2 expression in prostate cancer cells.

[Anti-apoptotic effect of the androgen receptor in human prostate cancer].

Prostate cancer is one of the common cancers in old men. Androgen ablation is a major option for the treatment of the metastatic diseases. However, most of the cancers progress to a more aggressive stage, so-called androgen-independent (or hormone refractory) relapse beyond any cure. The androgen receptor (AR) is an important factor in regulating the differentiation and proliferation of prostate epithelial cells, and also plays a critical role in cellular survival. Studies have demonstrated that aberrant activation of the AR is a major determinant in prostate cancer progression. We have provide a brief summary of AR-mediated cellular survival and an introduction to the advances of RNA interference techniques in silencing AR expression as a novel therapy for prostate cancer.