Valproic acid inhibits epithelial-mesenchymal transition in renal cell carcinoma by decreasing SMAD4 expression

Targeting apoptosis in clear cell renal cell carcinoma

Clear cell renal cell carcinoma (ccRCC) is the most prevalent subtype of renal cancer, accounting for approximately 80% of all renal cell cancers. Due to its exceptional inter- and intratumor heterogeneity, it is highly resistant to conventional systemic therapies. Targeting the evasion of cell death, one of cancer's hallmarks, is currently emerging as an alternative strategy for ccRCC. In this article, we review the current state of apoptosis-inducing therapies against ccRCC, including antisense oligonucleotides, BH3 mimetics, histone deacetylase inhibitors, cyclin-kinase inhibitors, inhibitors of apoptosis protein antagonists, and monoclonal antibodies. Although preclinical studies have shown encouraging results, these compounds fail to improve patients' outcomes significantly. Current evidence suggests that inducing apoptosis in ccRCC may promote tumor progression through apoptosis-induced proliferation, anastasis, and apoptosis-induced nuclear expulsion. Therefore, re-evaluating this approach is expected to enable successful preclinical-to-clinical translation.

New insights into fibrotic signaling in renal cell carcinoma

Fibrotic signaling plays a pivotal role in the development and progression of solid cancers including renal cell carcinoma (RCC). Intratumoral fibrosis (ITF) and pseudo-capsule (PC) fibrosis are significantly correlated to the disease progression of renal cell carcinoma. Targeting classic fibrotic signaling processes such as TGF-β signaling and epithelial-to-mesenchymal transition (EMT) shows promising antitumor effects both preclinically and clinically. Therefore, a better understanding of the pathogenic mechanisms of fibrotic signaling in renal cell carcinoma at molecular resolution can facilitate the development of precision therapies against solid cancers. In this review, we systematically summarized the latest updates on fibrotic signaling, from clinical correlation and molecular mechanisms to its therapeutic strategies for renal cell carcinoma. Importantly, we examined the reported fibrotic signaling on the human renal cell carcinoma dataset at the transcriptome level with single-cell resolution to assess its translational potential in the clinic.

Regulation of epithelial-mesenchymal transition by protein lysine acetylation

The epithelial-mesenchymal transition (EMT) is a vital driver of tumor progression. It is a well-known and complex trans-differentiation process in which epithelial cells undergo morphogenetic changes with loss of apical-basal polarity, but acquire spindle-shaped mesenchymal phenotypes. Lysine acetylation is a type of protein modification that favors reversibly altering the structure and function of target molecules via the modulation of lysine acetyltransferases (KATs), as well as lysine deacetylases (KDACs). To date, research has found that histones and non-histone proteins can be acetylated to facilitate EMT. Interestingly, histone acetylation is a type of epigenetic regulation that is capable of modulating the acetylation levels of distinct histones at the promoters of EMT-related markers, EMT-inducing transcription factors (EMT-TFs), and EMT-related long non-coding RNAs to control EMT. However, non-histone acetylation is a post-translational modification, and its effect on EMT mainly relies on modulating the acetylation of EMT marker proteins, EMT-TFs, and EMT-related signal transduction molecules. In addition, several inhibitors against KATs and KDACs have been developed, some of which can suppress the development of different cancers by targeting EMT. In this review, we discuss the complex biological roles and molecular mechanisms underlying histone acetylation and non-histone protein acetylation in the control of EMT, highlighting lysine acetylation as potential strategy for the treatment of cancer through the regulation of EMT.

Evaluation of the Effects of Valproic Acid Treatment on Cell Survival and Epithelial-Mesenchymal Transition-Related Features of Human Gastric Cancer Cells

PURPOSE

Metastasis is the most important feature of gastric cancer accounting for more than 90% of tumor-related mortality. As one of the main modulators of epithelial-mesenchymal transition (EMT), histone deacetylase inhibitors (HDACI) are considered rational candidates for cancer therapy. Valproic acid (VPA) is a HDACI with reported controversial effects on the EMT. The main aim of the current study was to evaluate the effects of VPA treatment on cell survival and EMT-related features of human gastric cancer cells (AGS).

METHODS

Methyl-thiazoltetrazolium (MTT) assay was utilized to assess the effect of VPA on the proliferation rate of cells. Apoptotic cell death was detected with Annexin V/PI staining. Migratory ability of cells following VPA treatment was assessed using a Boyden chamber test. The expression of EMT markers in AGS cells was analyzed using quantitative real-time RT-PCR.

RESULTS

Treatment with VPA significantly inhibited AGS cell proliferation compared with control. An increased rate of early and late apoptotic cells was observed following VPA exposure. It was demonstrated that VPA significantly diminished the cell migratory ability in AGS gastric cancer cells. Furthermore, treatment with VPA significantly decreased the expression of E-cadherin but increased the Vimentin expression.

CONCLUSIONS

Our results showed that VPA induces apoptosis and inhibits the cell proliferation and the migratory ability of AGS gastric cancer cells and may prove useful in the development of therapeutic agents for human gastric cancer. However, these preliminary findings call for further investigations to clarify the precise molecular mechanisms by which VPA modulates the EMT process in a cell type-specific manner.

Histone deacetylase inhibitors dysregulate DNA repair proteins and antagonize metastasis-associated processes

Purpose

We set out to determine whether clinically tested epigenetic drugs against class I histone deacetylases (HDACs) affect hallmarks of the metastatic process.

Methods

We treated permanent and primary renal, lung, and breast cancer cells with the class I histone deacetylase inhibitors (HDACi) entinostat (MS-275) and valproic acid (VPA), the replicative stress inducer hydroxyurea (HU), the DNA-damaging agent cis-platinum (L-OHP), and the cytokine transforming growth factor-β (TGFβ). We used proteomics, quantitative PCR, immunoblot, single cell DNA damage assays, and flow cytometry to analyze cell fate after drug exposure.

Results

We show that HDACi interfere with DNA repair protein expression and trigger DNA damage and apoptosis alone and in combination with established chemotherapeutics. Furthermore, HDACi disrupt the balance of cell adhesion protein expression and abrogate TGFβ-induced cellular plasticity of transformed cells.

Conclusion

HDACi suppress the epithelial–mesenchymal transition (EMT) and compromise the DNA integrity of cancer cells. These data encourage further testing of HDACi against tumor cells.

Electronic supplementary material

The online version of this article (10.1007/s00432-019-03118-4) contains supplementary material, which is available to authorized users.

WSZG inhibits BMSC-induced EMT and bone metastasis in breast cancer by regulating TGF-β1/Smads signaling

Bone metastasis of breast cancer causes severe skeletal-related events and poor prognosis. Wensheng Zhuanggu Formula (WSZG), a traditional Chinese prescription, is used to adjunctively treat breast cancer bone metastases in clinical practice. This study was undertaken to investigate the antibone-metastatic activities and mechanisms of WSZG extract by evaluating the effect of this formula on the cross-talk between bone marrow-derived mesenchymal stem cells (BMSCs) and breast cancer cells in triggering epithelial-mesenchymal transition (EMT) in vivo and in vitro. The results demonstrated that BMSCs might enhance the invasive and metastatic potentials of breast cancer cells as a consequence of EMT induction through direct cell-to-cell contact. WSZG treatment remarkably suppressed motility, invasion, EMT-related gene, and protein markers in BMSC-conditioned breast cancer cells and ameliorated bone metastases and damages in nude mice following co-injection of BMSCs and MDA-MB-231BO breast cancer cells. Further investigation showed that the transforming growth factor-β1 (TGF-β1)/Smads pathway was an important mechanism enabling BMSCs to induce EMT occurrence of breast cancer cells. WSZG treatment reversed BMSC-induced EMT by downregulating TGF-β1/Smads signaling. Thus, WSZG extracts may be regarded as a potential antibone-metastatic agent for breast cancer therapy.

The underlying molecular mechanism and potential drugs for treatment in papillary renal cell carcinoma: A study based on TCGA and Cmap datasets

Papillary renal cell carcinoma (PRCC) accounts for 15–20% of all kidney neoplasms and continually attracts attention due to the increase in the incidents in which it occurs. The molecular mechanism of PRCC remains unclear and the efficacy of drugs that treat PRCC lacks sufficient evidence in clinical trials. Therefore, it is necessary to investigate the underlying mechanism in the development of PRCC and identify additional potential anti-PRCC drugs for its treatment. The differently expressed genes (DEGs) of PRCC were identified, followed by Gene Ontology and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses for functional annotation. Then, potential drugs for PRCC treatment were predicted by Connectivity Map (Cmap) based on DEGs. Furthermore, the latent function of query drugs in PRCC was explored by integrating drug-target, drug-pathway and drug-protein interactions. In total, 627 genes were screened as DEGs, and these DEGs were annotated using KEGG pathway analyses and were clearly associated with the complement and coagulation cascades, amongst others. Then, 60 candidate drugs, as predicted based on DEGs, were obtained from the Cmap database. Vorinostat was considered as the most promising drug for detailed discussion. Following protein-protein interaction (PPI) analysis and molecular docking, vorinostat was observed to interact with C3 and ANXN1 proteins, which are the upregulated hub genes and may serve as oncologic therapeutic targets in PRCC. Among the top 20 metabolic pathways, several significant pathways, such as complement and coagulation cascades and cell adhesion molecules, may greatly contribute to the development and progression of PRCC. Following the performance of the PPI network and molecular docking tests, vorinostat exhibited a considerable and promising application in PRCC treatment by targeting C3 and ANXN1.

Sunitinib-suppressed miR-452-5p facilitates renal cancer cell invasion and metastasis through modulating SMAD4/SMAD7 signals

PURPOSE

Although microRNAs (miRNAs) were revealed as crucial modulators in tumor metastasis and target therapy, our understanding of their roles in metastatic renal cell carcinoma (mRCC) and Sunitinib treatment was limited. Here we sought to identify human miRNAs that acted as key regulators in renal cancer metastasis and Sunitinib treatment.

EXPERIMENTAL DESIGN

We focused on 2 published microarray data to select out our anchored miRNA and then explored the roles of miR-452-5p both in vitro and in vivo, which was downregulated after Sunitinib treatment while upregulated in metastasis renal cell carcinoma (RCC) tissues.

RESULTS

Here, we discovered that treating with Sunitinib, the targeted receptor tyrosine kinase inhibitor (TKI), inhibited renal cancer cell migration and invasion via attenuating the expression of miR-452-5p. The novel identified miR-452-5p was upregulated and associated with poor prognosis in RCC. Preclinical studies using multiple RCC cells and xenografts model illustrated that miR-452-5p could promote RCC cell migration and invasion in vitro and in vivo. Mechanistically, P65 could directly bind to the miR-452-5p promoter and thus transcriptionally induce miR-452-5p expression, which led to post-transcriptionally abrogate SMAD4 expression, thus inhibition of its downstream gene SMAD7.

CONCLUSION

Our study presented a road map for targeting this newly identified miR-452-5p and its SMAD4/SMAD7 signals pathway, which imparted a new potential therapeutic strategy for mRCC treatment.