Programmed cell death 4 overexpression enhances sensitivity to cisplatin via the JNK/c-Jun signaling pathway in bladder cancer

BPA Decreases PDCD4 in Bovine Granulosa Cells Independently of miR-21 Inhibition

microRNAs (miRNAs) are susceptible to environmental factors that might affect cellular function and impose negative effects on female reproduction. miR-21 is the most abundant miRNA in bovine granulosa cells and is widely reported as affected by Bisphenol A (BPA) exposure, yet the cause and consequences are not entirely elucidated. BPA is a synthetic endocrine disruptor associated with poor fertility. miR-21 function in bovine granulosa cells is investigated utilizing locked nucleic acid (LNA) oligonucleotides to suppress miR-21. Before measuring apoptosis and quantifying miR-21 apoptotic targets PDCD4 and PTEN, transfection was optimized and validated. BPA was introduced to see how it affects miR-21 regulation and which BPA-mediated effects are influenced by miR-21. miR-21 knockdown and specificity against additional miRNAs were confirmed. miR-21 was found to have antiapoptotic effects, which could be explained by its effect on the proapoptotic target PDCD4, but not PTEN. Previous findings of miR-21 overexpression were validated using BPA treatments, and the temporal influence of BPA on miR-21 levels was addressed. Finally, BPA effects on upstream regulators, such as VMP1 and STAT3, explain the BPA-dependent upregulation of miR-21 expression. Overall, this research enhances our understanding of miR-21 function in granulosa cells and the mechanisms of BPA-induced reproductive impairment.

Exogenous NO induces apoptosis of hepatocellular carcinoma cells via positive p38/JNK signaling pathway and negative ERK signaling pathways

JS-K as an exogenous NO donor could release NO after activation by glutathione S-transferases (GSTs). The present study explores the effects of JS-K on MAPK pathway in HepG2 and Bel-7402 cells. JS-K significantly prompted apoptosis and SB203580 (a p38 inhibitor) and SP600125 (a JNK inhibitor) prior to JS-K could partly reverse apoptosis and activation of cleaved-caspase-3 and cleaved PARP. However, U0126 (a MEK inhibitor) strengthened the cell apoptosis and the expressions of cleaved-caspase-3 and cleaved PARP. JS-K caused phosphorylation of p38 MAPK and JNK but attenuated phosphorylation of ERK, which were reversed by Carboxy-PTIO (a NO scavenger). Meanwhile, the phosphorylation of HSP27, c-JUN and ATF-2 were activated in JS-K-treated cells. SB203580 and SP600125 could attenuate phosphorylation of p38 MAPK and JNK, respectively. The phosphorylation in downstream substrates of p38 MAPK and JNK was also abolished by SB203580 and SP600125 in JS-K-treated cells. Additionally, JS-K decreased phosphorylation of c-Raf, which subsequently caused a decrease of MEK1/2 phosphorylation. Several downstream targets of ERK1/2 including p90RSK and transcription factors (e.g., Elk-1, c-Myc and c-Fos) were inhibited. U0126 potentiated JS-K-induced inhibitory effect of Raf/MEK/ERK pathway. The same results were also observed in the downstream substrates of ERK1/2 including p90RSK, Elk-1, c-Myc and c-Fos. Moreover, Carboxy-PTIO abolished the inhibitory effect of Raf/MEK/ERK pathway triggered by JS-K. Finally, JS-K significantly suppressed the growth of rat primary hepatic carcinoma via MAPK pathway in vivo. Taken together, JS-K can induce hepatocellular carcinoma cells apoptosis through its activation of JNK and p38 MAPK and inactivation of Raf/MEK/ERK signaling pathways.

Association of the Epithelial-Mesenchymal Transition (EMT) with Cisplatin Resistance

Therapy resistance is a characteristic of cancer cells that significantly reduces the effectiveness of drugs. Despite the popularity of cisplatin (CP) as a chemotherapeutic agent, which is widely used in the treatment of various types of cancer, resistance of cancer cells to CP chemotherapy has been extensively observed. Among various reported mechanism(s), the epithelial-mesenchymal transition (EMT) process can significantly contribute to chemoresistance by converting the motionless epithelial cells into mobile mesenchymal cells and altering cell-cell adhesion as well as the cellular extracellular matrix, leading to invasion of tumor cells. By analyzing the impact of the different molecular pathways such as microRNAs, long non-coding RNAs, nuclear factor-κB (NF-ĸB), phosphoinositide 3-kinase-related protein kinase (PI3K)/Akt, mammalian target rapamycin (mTOR), and Wnt, which play an important role in resistance exhibited to CP therapy, we first give an introduction about the EMT mechanism and its role in drug resistance. We then focus specifically on the molecular pathways involved in drug resistance and the pharmacological strategies that can be used to mitigate this resistance. Overall, we highlight the various targeted signaling pathways that could be considered in future studies to pave the way for the inhibition of EMT-mediated resistance displayed by tumor cells in response to CP exposure.

Downstream Effectors of ILK in Cisplatin-Resistant Ovarian Cancer

Despite good responses to first-line treatment with platinum-based combination chemotherapy, most ovarian cancer patients will relapse and eventually develop platinum-resistant disease with poor prognosis. Although reports suggest that integrin-linked kinase (ILK) is a potential target for ovarian cancer treatment, identification of ILK downstream effectors has not been fully explored. The purpose of this study was to investigate the molecular and biological effects of targeting ILK in cisplatin-resistant ovarian cancer. Western blot analysis showed that phosphorylation levels of ILK were higher in cisplatin-resistant compared with cisplatin-sensitive ovarian cancer cells. Further immunohistochemical analysis of ovarian cancer patient samples showed a significant increase in phosphorylated ILK levels in the tumor tissue when compared to normal ovarian epithelium. Targeting ILK by small-interfering RNA (siRNA) treatment reduced cisplatin-resistant cell growth and invasion ability, and increased apoptosis. Differential gene expression analysis by RNA sequencing (RNA-Seq) upon ILK-siRNA transfection followed by Ingenuity Pathway Analysis (IPA) and survival analysis using the Kaplan-Meier plotter database identified multiple target genes involved in cell growth, apoptosis, invasion, and metastasis, including several non-coding RNAs. Taken together, results from this study support ILK as an attractive target for ovarian cancer and provide potential ILK downstream effectors with prognostic and therapeutic value.

Mesenchymal stromal cell-derived exosomes improve pulmonary hypertension through inhibition of pulmonary vascular remodeling

Background

Pulmonary hypertension (PH) is a life-threatening disease characterized by pulmonary vascular remodeling, right ventricular hypertrophy and failure. So far no effective treatment exists for this disease; hence, novel approaches are urgently needed. The aim of the present research was to observe the treatment effect of mesenchymal stromal cell derived exosomes and reveal the mechanism.

Methods

Monocrotaline (MCT)-induced PH in rats and hypoxia-induced cell damage model were established, respectively. Exosomes derived from the supernatant of human umbilical cord mesenchymal stem cells (MSC-exo) were injected into MCT-PH model rat or added into the cells cultured medium. Immunohistochemistry, quantitative real-time polymerase chain reaction (qRT-PCR) and western blot methods were used in vivo and vitro.

Results

The results showed that MSC-exo could significantly attenuate right ventricular (RV) hypertrophy and pulmonary vascular remodelling in MCT-PH rats. In the cell culture experiments, we found that MSC-exo could significantly inhibit hypoxia-induced pulmonary arterial endothelial cell (PAEC) apoptosis and pulmonary arterial smooth muscle cells (PASMC) proliferation. Furthermore, the pulmonary arterioles endothelial-to-mesenchymal transition (EndMT) was obviously suppressed. Moreover, the present study suggest that MSC-exo can significantly upregulate the expression of Wnt5a in MCT-PH rats and hypoxic pulmonary vascular cells. Furthermore, with Wnt5a gene silencing, the therapeutic effect of MSC-exo against hypoxia injury was restrained.

Conclusions

Synthetically, our data provide a strong evidence for the therapeutic of MSC-exo on PH, more importantly, we confirmed that the mechanism was associated with up-regulation of the expression of Wnt5a. These results offer a theoretical basis for clinical prevention and treatment of PH.

Control Mechanisms of the Tumor Suppressor PDCD4: Expression and Functions

PDCD4 is a novel tumor suppressor to show multi-functions inhibiting cell growth, tumor invasion, metastasis, and inducing apoptosis. PDCD4 protein binds to the translation initiation factor eIF4A, some transcription factors, and many other factors and modulates the function of the binding partners. PDCD4 downregulation stimulates and PDCD4 upregulation inhibits the TPA-induced transformation of cells. However, PDCD4 gene mutations have not been found in tumor cells but gene expression was post transcriptionally downregulated by micro environmental factors such as growth factors and interleukins. In this review, we focus on the suppression mechanisms of PDCD4 protein that is induced by the tumor promotors EGF and TPA, and in the inflammatory conditions. PDCD4-protein is phosphorylated at 2 serines in the SCF^βTRCP ubiquitin ligase binding sequences via EGF and/or TPA induced signaling pathway, ubiquitinated, by the ubiquitin ligase and degraded in the proteasome system. The PDCD4 protein synthesis is inhibited by microRNAs including miR21.

Characterization of mRNA Expression and Endogenous RNA Profiles in Bladder Cancer Based on The Cancer Genome Atlas (TCGA) Database

Background

Bladder cancer is a multifactorial disease with increasing incidence and mortality. Genetic alterations and altered expressions of mRNAs, long non-coding RNAs (lncRNAs), and miRNAs have been shown to play important roles in the tumorigenesis of bladder cancer. However, the functions of key RNAs and their regulatory network in bladder cancer are still to be elucidated.

Material/Methods

RNA profiles were downloaded from The Cancer Genome Atlas (TCGA) database. The differentially expressed mRNAs, lncRNAs, and miRNAs in bladder cancer were acquired through analyses of data from 414 bladder cancer tissues and 19 normal bladder tissues. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analysis was performed by using “DAVID6.8” and the R package “ClusterProfile”. Protein–protein interaction and competing endogenous RNA (ceRNA) networks were constructed by using “STRING” database and Cytoscape 3.6.2. Based on the clinical data and Cox regression, a prognosis model was established, and survival analysis was performed.

Results

A total of 1819 mRNAs, 659 lncRNAs, and 160 miRNAs were identified as significantly differentially expressed in bladder cancer of which 52 mRNAs, 58 lncRNAs, and 22 miRNAs were incorporated in the ceRNA network. CFL2 and TPM2 were found to be downregulated and showed significant correlation to each other in bladder cancer. HOXB5 and 6 lncRNAs (ADAMTS9-AS1, AC112721.1, LINC00460, AC110491.1, LINC00163, and HCG22) were strongly associated with high-grade, disease stages, and overall survival.

Conclusions

In this study, we have identified differentially expressed mRNAs, lncRNAs, and miRNAs in bladder cancer which were strongly associated with oncogenesis and prognosis. Further experimental studies are necessary to validate these results.

Long non-coding RNA CASC15 promotes melanoma progression by epigenetically regulating PDCD4

Background

Long non-coding RNAs (LncRNAs) have been identified as critical regulators in a variety of cancer types. Cancer susceptibility candidate 15 (CASC15), a lncRNA located at chromosome 6p22.3, has been discovered to participate in melanoma progression and phenotype switching. Nevertheless, the roles and molecular mechanisms of CASC15 in melanoma are far from being understood.

Results

We found that CASC15 expression was up-regulated in melanoma tissues and associated with advanced pathological stages. Function experiments displayed that CASC15 knockdown hindered proliferation, facilitated apoptosis and suppressed invasion, while CASC15 overexpression facilitated proliferation and invasion in melanoma cells. Further mechanistic analysis showed that CASC15 epigenetically silenced the expression of programmed cell death 4 (PDCD4) by recruiting EZH2 and increasing H3K27me3 level at the promoter region of PDCD4. Additionally, PDCD4 overexpression inhibited proliferation, enhanced apoptosis and decreased invasion of melanoma cells. Moreover, CASC15-knockdown-induced anti-cancer effects were abated by PDCD4 down-regulation. Furthermore, depletion of CASC15 blocked tumor growth of melanoma by up-regulating PDCD4 in vivo.

Conclusions

CASC15 acts as an oncogene by negatively regulating PDCD4 expression via recruiting EZH2 and subsequently increasing H3K27me3 level. Together, our study indicates that CASC15/EZH2/PDCD4 may serve as a promising therapeutic target for melanoma intervention.