In PTEN-deficient prostate cancers, AKT signaling may be activated upon suppression of androgen receptor signaling. Activation of AKT as well as NF-κB signaling involves a key regulatory protein complex containing PHLPP, FKBP51 and IKKα. Here, we report a critical role of lncRNA PCAT1 in regulating the PHLPP/FKBP51/IKKα complex and progression of castration-resistant prostate cancer (CRPC). Using database queries, bioinformatic analyses, as well as RIP and RNA pull-down assays, we discovered and validated that the lncRNA-PCAT1 perturbs the PHLPP/FKBP51/IKKα complex and activates AKT and NF-κB signaling. Expression of lncRNA-PCAT1 is positively linked to CRPC progression. PCAT1 binds directly to FKBP51, displacing PHLPP from the PHLPP/FKBP51/IKKα complex, leading to activation of AKT and NF-κB signaling. Targeting PCAT1 restores PHLPP binding to FKBP1 leading to suppression of AKT signaling. Preclinical study in a mouse model of CRPC suggests therapeutic potential by targeting lncRNA PCAT1 to suppress CRPC progression. Together, the newly identified PCAT1/FKBP51/IKKα complex provides mechanistic insight in the interplay between AKT, NF-κB and AR signaling in CRPC, and the preclinical studies suggest that a novel role for PCAT1 as a therapeutic target.

Colorectal cancer (CRC) is the third most frequently diagnosed cancer and the third leading cause of cancer death in the Western world. Chemotherapy has been shown to improve outcomes in patients with CRC; however, only selected patients would benefit from this treatment. We aimed to identify predictors of response to chemotherapy in CRC using circulating microRNAs (miRNAs). We studied differential miRNA expression by miRNA array from serum of 253 patients who had chemotherapy treatment. We screened the differentially expressed serum miRNAs with TaqMan low-density arrays using pooled CRC patient serum samples. Differential expression was validated using hydrolysis probe-based stem-loop quantitative reverse transcription PCR in individual samples. We performed additional unsupervised cluster to analyse the differential expression of serum miRNA between the chemosensitive and chemoresistant patients. A distinct miRNA expression signature in response to chemotherapy was identified. The TaqMan low-density array results demonstrated that 17 serum miRNAs could predict chemosensitivity and chemoresistance. The quantitative reverse transcription PCR analysis further identified a profile of five serum miRNAs (miR-20a, miR-130, miR-145, miR-216 and miR-372) as a biomarker for predicting the chemosensitivity of CRC. The areas under the receiver operating characteristic curve of this five-serum miRNA signature were 0.841 and 0.918 for the two sets of serum samples, respectively. We identified a group of miRNA predictors in response to chemosensitivity for CRC patients. This could lead to a significant improvement in chemotherapy regimen selection strategy and personalized CRC management.

Therefore, we propose a new mechanism in which Smad3/Sox5/Twist1 promotes EMT and contributes to PCa progression.

13-Methyltetradecanoic acid (13-MTD), a saturated branched-chain fatty acid purified from soy fermentation products, induces apoptosis in human cancer cells. We investigated the inhibitory effects and mechanism of action of 13-MTD on T-cell non-Hodgkin’s lymphoma (T-NHL) cell lines both in vitro and in vivo. Growth inhibition in response to 13-MTD was evaluated by the cell counting kit-8 (CCK-8) assay in three T-NHL cell lines (Jurkat, Hut78, EL4 cells). Flow cytometry analyses were used to monitor the cell cycle and apoptosis. Proteins involved in 13-MTD-induced apoptosis were examined in Jurkat cells by western blotting. We found that 13-MTD inhibited proliferation and induced the apoptosis of T-NHL cell lines. 13-MTD treatment also induced a concentration-dependent arrest of Jurkat cells in the G1-phase. During 13-MTD-induced apoptosis in Jurkat cells, the cleavage of caspase-3 and poly ADP-ribose polymerase (PARP, a caspase enzymolysis product) were detected after incubation for 2 h, and increased after extending the incubation time. However, there was no change in the expression of Bcl-2 or c-myc proteins. The appearance of apoptotic Jurkat cells was accompanied by the inhibition of AKT and nuclear factor-kappa B (NF-κB) phosphorylation. In addition, 13-MTD could also effectively inhibit the growth of T-NHL tumors in vivo in a xenograft model. The tumor inhibition rate in the experimental group was 40%. These data indicate that 13-MTD inhibits proliferation and induces apoptosis through the down-regulation of AKT phosphorylation followed by caspase activation, which may provide a new approach for treating T-cell lymphomas.