Targeted therapies are considered to be the future of cancer treatment. However, the mechanism through which intracellular signaling pathways coordinate to modulate oncogenesis remains to be elucidated. In this study, we describe a novel crosstalk among ERK, AKT and Hippo-YAP pathways, with CD44 as an upstream regulator. High cell density leads to activation of ERK and AKT but inactivation of YAP in cancer cells. CD44 modulates cell proliferation and cell cycle but not apoptosis. The expression and activity of cell cycle genes were cooperatively regulated by ERK, AKT and Hippo-YAP signaling pathways through CD44-mediated mechanisms. In addition, CD44 depletion abrogates cancer stem cell properties of tumor initiating cells. Taken together, we described a paradigm where CD44 functions as an upstream regulator sensing the extracellular environment to modulate ERK, AKT and Hippo-YAP pathways which cooperatively control downstream gene expression to modulate cell contact inhibition of proliferation, cell cycle progression and maintenance of tumor initiating cells. Our current study provides valuable information to design targeted therapeutic strategies in cancers.

Apelin is an endogenous ligand of seven-transmembrane G protein-coupled receptor APJ. Apelin and APJ are distributed in various tissues, including the heart, lung, kidney, and even in tumor tissues. Studies show that apelin mRNA is highly expressed in the inner stripe of kidney outer medulla, which plays an important role in process of water and sodium balance. Additionally, more studies also indicate that apelin/APJ system exerts a broad range of activities in kidney. Therefore, we review the role of apelin/APJ system in kidney diseases such as renal fibrosis, renal ischemia/reperfusion injury, diabetic nephropathy, polycystic kidney disease, and hemodialysis (HD). Apelin/APJ system can improve renal interstitial fibrosis by reducing the deposition of extracellular matrix. Apelin/APJ system significantly reduces renal ischemia/reperfusion injury by inhibiting renal cell death. Apelin/APJ system involves the progression of diabetic nephropathy (DN). Apelin/APJ system also predicts the process of polycystic kidney disease. Besides, apelin/APJ system prevents some dialysis complications in HD patients. And apelin/APJ system alleviates chronic kidney disease (CKD) by inhibiting vascular calcification (VC). Overall, apelin/APJ system plays diversified roles in kidney disease and may be a potential target for the treatment of kidney disease.

Natural killer (NK) cells are critical effectors in the immune response against malignancy and infection, and microRNAs (miRNAs) play important roles in NK cell biology. Here we examined miRNA profiles of human NK cells from different cell compartments (peripheral blood, cord blood, and uterine deciduas) and of NKT and T cells from peripheral blood, and we identified a novel miRNA, miR-362-5p, that is highly expressed in human peripheral blood NK (pNK) cells. We also demonstrated that CYLD, a negative regulator of NF-κB signaling, was a target of miR-362-5p in NK cells. Furthermore, we showed that the over-expression of miR-362-5p enhanced the expression of IFN-γ, perforin, granzyme-B, and CD107a in human primary NK cells, and we found that silencing CYLD with a small interfering RNA (siRNA) mirrored the effect of miR-362-5p over-expression. In contrast, the inhibition of miR-362-5p had the opposite effect in NK cells, which was abrogated by CYLD siRNA, suggesting that miR-362-5p promotes NK-cell function, at least in part, by the down-regulation of CYLD. These results provide a resource for studying the roles of miRNAs in human NK cell biology and contribute to a better understanding of the physiologic significance of miRNAs in the regulation of NK cell function.

The eukaryotic cell cycle is controlled by a complex regulatory network, which is still poorly understood. Here we demonstrate that TRPS1, an atypical GATA factor, modulates cell proliferation and controls cell cycle progression. Silencing TRPS1 had a differential effect on the expression of nine key cell cycle-related genes. Eight of these genes are known to be involved in the regulation of the G2 phase and the G2/M transition of the cell cycle. Using cell synchronization studies, we confirmed that TRPS1 plays an important role in the control of cells in these phases of the cell cycle. We also show that silencing TRPS1 controls the expression of 53BP1, but not TP53. TRPS1 silencing also decreases the expression of two histone deacetylases, HDAC2 and HDAC4, as well as the overall HDAC activity in the cells, and leads to the subsequent increase in the acetylation of histone4 K16 but not of histone3 K9 or K18. Finally, we demonstrate that TRPS1 expression is elevated in luminal breast cancer cells and luminal breast cancer tissues as compared with other breast cancer subtypes. Overall, our study proposes that TRPS1 acts as a central hub in the control of cell cycle and proliferation during cancer development.

No abstract

Purpose: Although tyrosine kinase inhibitors (TKI) such as imatinib provide an effective treatment against Bcr-Abl kinase activity in the mature cells of patients with chronic myelogenous leukemia (CML), TKIs probably cannot eradicate the leukemia stem cell (LSC) population. Therefore, alternative therapies are required to target both mature CML cells with wild-type (WT) or mutant Bcr-Abl and LSCs. To investigate the effect of C086, a derivative of curcumin, on imatinib-resistant cells, we explored its underlying mechanisms of Bcr-Abl kinase and heat shock protein 90 (Hsp90) function inhibition.Experimental Design: Biochemical assays were used to test ABL kinase activity; fluorescence measurements using recombinant NHsp90, Hsp90 ATPase assay, immunoprecipitation, and immunoblotting were applied to examine Hsp90 function. Colonyforming unit, long-term culture-initiating cells (LTC-IC), and flow cytometry were used to test CML progenitor and stem cells.Results: Biochemical assays with purified recombinant Abl kinase confirmed that C086 can directly inhibit the kinase activity of Abl, including WT and the Q252H, Y253F, and T315I mutations. Furthermore, we identified C086 as a novel Hsp90 inhibitor with the capacity to disrupt the Hsp90 chaperone function in CML cells. Consequently, it inhibited the growth of both imatinib-sensitive and -resistant CML cells. Interestingly, C086 has the capacity to inhibit LTC-ICs and to induce apoptosis in both CD34Conclusions: Dual suppression of Abl kinase activity and Hsp90 chaperone function by C086 provides a new therapeutic strategy for treating Bcr-Abl-induced leukemia resistant to TKIs.

Activation of the IKK-NFκB pathway increases the resistance of cancer cells to ionizing radiation (IR). This effect has been largely attributed to the induction of anti-apoptotic proteins by NFκB. Since efficient repair of DNA double strand breaks (DSBs) is required for the clonogenic survival of irradiated cells, we investigated if activation of the IKK-NFκB pathway also regulates DSB repair to promote cell survival after IR. We found that inhibition of the IKK-NFκB pathway with a specific IKKβ inhibitor significantly reduced the repair of IR-induced DSBs in MCF-7 cells. The repair of DSBs was also significantly inhibited by silencing IKKβ expression with IKKβ shRNA. However, down-regulation of IKKα expression with IKKα shRNA had no significant effect on the repair of IR-induced DSBs. Similar findings were also observed in IKKα and/or IKKβ knockout mouse embryonic fibroblasts (MEFs). More importantly, inhibition of IKKβ with an inhibitor or down-regulation of IKKβ with IKKβ shRNA sensitized MCF-7 cells to IR-induced clonogenic cell death. DSB repair function and resistance to IR were completely restored by IKKβ reconstitution in IKKβ-knockdown MCF-7 cells. These findings demonstrate that IKKβ can regulate the repair of DSBs, a previously undescribed and important IKKβ kinase function; and inhibition of DSB repair may contribute to cance cell radiosensitization induced by IKKβ inhibition. As such, specific inhibition of IKKβ may represents a more effective approach to sensitize cancer cells to radiotherapy.

Protein Kinase D3 (PRKD3) functions as an important oncogenic driver in invasive breast cancer, which is the leading cause of women mortality. However, PRKD3 regulating network is largely unknown. In this study, we systematically explored PRKD3 regulating networks via investigating phosphoproteome, interactome and transcriptome to uncover the molecular mechanism of PRKD3 in invasive breast cancer. Using iTRAQ, 270 proteins were identified as PRKD3 regulated phosphoproteins from 4619 phosphosites matching 3666 phosphopeptides from 2016 phosphoproteins with p-value <0.005. Transcriptome analysis using affymetrix microarray identified 45 PRKD3 regulated genes, in which 20 genes were upregulated and 25 genes were downregulated with p-value <0.005 upon silencing PRKD3. Using Co-IP in combination of MS identification, 606 proteins were identified to be PRKD3 interacting proteins from 2659 peptides. Further network analysis of PRKD3 regulated phosphoproteins, interacting proteins and regulated genes, reveals 19 hub nodes, including ELAVL1, UBC and BRCA1. UBC was recognized as the most common hub node in PRKD3 regulating networks. The enriched pathway analysis reveals that PRKD3 regulates pathways contributing to multiple cancer related events, including cell cycle, migration and others. Enrichment of cell cycle and cell mobility related pathways across PRKD3 networks, explained the observations that depletion of oncogenic PRKD3 led to alternation of cell cycle and decrease of cell migration ability. Taken together, our current study provided valuable information on the roles as well as the molecular mechanisms of PRKD3 in invasive breast cancer.