Decreased level of RASSF6 in sporadic colorectal cancer and its anti-tumor effects both in vitro and in vivo

Vactosertib potently improves anti-tumor properties of 5-FU for colon cancer

BACKGROUND

Several studies have shown that the TGF-β signaling pathway plays a critical role in colorectal cancer (CRC) pathogenesis. The aim of the current study is to investigate the therapeutic potential of Vactosertib (EW-7197), a selective inhibitor of TGF-β receptor type I, either alone or in combination with the standard first-line chemotherapeutic treatment, 5-Fluorouracil (5-FU), in CRC progression in both cellular and animal models.

METHODS

Real-Time PCR, Zymography, enzyme-linked immunosorbent assay (ELISA), Hematoxylin and Eosin (H&E) tissue staining, and Flow cytometry techniques were applied to determine the anti-tumor properties of this novel TGF-β inhibitor in in vitro (CT-26 cell line) and in vivo (inbred BALB/C mice) samples.

RESULTS

Our findings showed that Vactosertib decreased cell proliferation and induced spheroid shrinkage. Moreover, this inhibitor suppressed the cell cycle and its administration either alone or in combination with 5-FU induced apoptosis by regulating the expression of p53 and BAX proteins. It also improved 5-FU anti-cancer effects by decreasing the tumor volume and weight, increasing tumor necrosis, and regulating tumor fibrosis and inflammation in an animal model. Vactosertib also enhanced the inhibitory effect of 5-FU on invasive behavior of CRC cells by upregulating the expression of E-cadherin and inhibiting MMP-9 enzymatic activity.

CONCLUSION

This study demonstrating the potent anti-tumor effects of Vactosertib against CRC progression. Our results clearly suggest that this inhibitor could be a promising agent reducing CRC tumor progression when administered either alone or in combination with standard treatment in CRC patients.

Loss of Tumor Suppressor C9orf9 Promotes Metastasis in Colorectal Cancer

The whole genome sequencing of tumor samples identifies thousands of somatic mutations. However, the function of these genes or mutations in regulating cancer progression remains unclear. We previously performed exome sequencing in patients with colorectal cancer, and identified one splicing mutation in C9orf9. The subsequent target sequencing of C9orf9 gene based on a validation cohort of 50 samples also found two function mutations, indicating that the loss of wild-type C9orf9 may participate in the tumorigenesis of colorectal cancer. In this research, we aimed to further confirm the function of C9orf9 in the CRC phenotype. Our Q-PCR analysis of the tumor and matched normal samples found that C9orf9 was downregulated in the CRC samples. Function assays revealed that C9orf9 exerts its tumor suppressor role mainly on cancer cell migration and invasion, and its loss was essential for certain tumor-microenvironment signals to induce EMT and metastasis in vivo. RNA-sequencing showed that stable-expressing C9orf9 can inhibit the expression of several metastasis-related genes and pathways, including vascular endothelial growth factor A (VEGFA), one of the essential endothelial cell mitogens which plays a critical role in normal physiological and tumor angiogenesis. Overall, our results showed that the loss of C9orf9 contributes to the malignant phenotype of CRC. C9orf9 may serve as a novel metastasis repressor for CRC.

Regulation of RASSF by non-coding RNAs in different cancers

Ras-association domain family (RASSF) proteins are tumor suppressors and have gained phenomenal limelight because of their mechanistic role in the prevention/inhibition of carcinogenesis and metastasis. Decades of research have demystified wide ranging activities of RASSF molecules in multiple stages of cancers. Although major fraction of RASSF molecules has tumor suppressive roles, yet there is parallel existence of proof-of-concept about moonlighting activities of RASSF proteins as oncogenes. RASSF proteins tactfully rewire signaling cascades for prevention of cancer and metastasis but circumstantial evidence also illuminates oncogenic role of different RASSF proteins in different cancers. In this review we have attempted to provide readers an overview of the complex interplay between non-coding RNAs and RASSF proteins and how these versatile regulators shape the landscape of carcinogenesis and metastasis.

Rigosertib elicits potent anti-tumor responses in colorectal cancer by inhibiting Ras signaling pathway

BACKGROUND

The therapeutic potency of Rigosertib (RGS) in the treatment of the myelodysplastic syndrome has been investigated previously, but little is known about its mechanisms of action.

METHODS

The present study integrates systems and molecular biology approaches to investigate the mechanisms of the anti-tumor effects of RGS, either alone or in combination with 5-FU in cellular and animal models of colorectal cancer (CRC).

RESULTS

The effects of RGS were more pronounced in dedifferentiated CRC cell types, compared to cell types that were epithelial-like. RGS inhibited cell proliferation and cell cycle progression in a cell-type specific manner, and that was dependent on the presence of mutations in KRAS, or its down-stream effectors. RGS increased both early and late apoptosis, by regulating the expression of p53, BAX and MDM2 in tumor model. We also found that RGS induced cell senescence in tumor tissues by increasing ROS generation, and impairing oxidant/anti-oxidant balance. RGS also inhibited angiogenesis and metastatic behavior of CRC cells, by regulating the expression of CD31, E-cadherin, and matrix metalloproteinases-2 and 9.

CONCLUSION

Our findings support the therapeutic potential of this potent RAS signaling inhibitor either alone or in combination with standard regimens for the management of patients with CRC.

MiR-581/SMAD7 Axis Contributes to Colorectal Cancer Metastasis: A Bioinformatic and Experimental Validation-Based Study

Metastasis is a well-known poor prognostic factor and primary cause of mortality in patients with colorectal cancer (CRC). Recently, with the progress of high through-put sequencing, aberrantly expressed non-coding RNAs (ncRNAs) were found to participate in the initiation and development of cancer. However, the mechanisms of ncRNA-mediated regulation of metastasis in CRC remain largely unknown. In this study, we systematically analyzed the expression network of microRNAs (miRNAs) and genes in CRC metastasis using bioinformatics, and discovered that the miR-581/SMAD7 axis could be a potential factor that drives CRC metastasis. A dual luciferase report assay and protein analysis confirmed the binding relationship between miR-581 and SMAD7. Further functional assays revealed that miR-581 inhibition could suppress cell proliferation and induce apoptosis in SW480 cells. Up-regulation or down-regulation of miR-581 could both affect cell invasion capacity and modulate epithelial to mesenchymal transition (EMT) via a SMAD7/TGFβ signaling pathway. In conclusion, our findings elucidated that miR-581/SMAD7 could be essential for CRC metastasis, and may serve as a potential therapeutic target for CRC patients.

Transcriptomic analysis reveals the oncogenic role of S6K1 in hepatocellular carcinoma

The p70 ribosomal protein S6 kinase 1 (S6K1), a serine/threonine kinase, is commonly overexpressed in a variety of cancers. However, its expression level and functional roles in hepatocellular carcinoma (HCC), which ranks as the third leading cause of cancer-related death worldwide, is still largely unknown. In the current report, we show the in vivo and in vitro overexpression of S6K1 in HCC. In the functional analysis, we demonstrate that S6K1 is required for the proliferation and colony formation abilities in HCC. By using comparative transcriptomic analysis followed by gene ontology enrichment analysis and Ingenuity Pathway Analysis, we find that the depletion of S6K1 can elevate the expression of a cluster of apoptotic genes, tumor suppressor genes and immune responsive genes. Moreover, the knockdown of S6K1 is predicted to reduce the tumorigenicity of HCC through the regulation of hubs of genes including STAT1, HDAC4, CEBPA and ONECUT1. In conclusion, we demonstrate the oncogenic role of S6K1 in HCC, suggesting the possible use of S6K1 as a therapeutic target for HCC treatment.

The Role of RASSF1 Methylation in Lung Carcinoma

Lung carcinoma is the most frequently diagnosed malignant neoplasms and mainly consists of small-cell lung carcinoma (SCLC) and non-small-cell lung carcinoma (NSCLC). Large number of lung carcinoma patients have poor outcomes due to the late diagnosis and the limited therapeutic options. Previous attempts have proved that the evolution of lung carcinoma is a multistep molecular aberration which various genetic or epigenetic alterations may be take part in. Among these molecular aberrations, the inactivation of tumor suppressor gene has been widely observed in all types of carcinoma including lung carcinoma. As a vital inactivated mechanism, DNA methylation of tumor suppressor gene is frequently found in lung cancer. To gain exhaustive comprehension of the carcinogenesis of lung carcinoma, we summarize our current knowledge on DNA methylation of RASSF1 (RAS-Association Domain Family 1) and its clinical significance in lung carcinoma.

RASSF6-TRIM16 axis promotes cell proliferation, migration and invasion in esophageal squamous cell carcinoma

Ras-association (RA) domain family number 6 (RASSF6) is a member of the Ras-association domain protein family. It is epigenetically inactive and negatively regulates the malignant progression of some tumors. However, its precise role in esophageal squamous cell carcinoma (ESCC) has not been reported. In this study, we performed immunohistochemistry (IHC) assay. The results show that RASSF6 is upregulated in ESCC and that the elevated expression level of RASSF6 is associated with lymph node metastasis and poor survival of ESCC patients. Consistent with the clinical observations, the upregulation of RASSF6 greatly promotes ESCC cell proliferation, migration and invasion as well as the cell cycle transition to G1/S phase in vitro. According to models in vivo, the downregulation of RASSF6 considerably inhibits ESCC tumor growth and lung metastasis. Mechanistically, RASSF6 negatively regulates the tumor suppressor tripartite-motif-containing protein 16 (TRIM16) by promoting its ubiquitination-dependent degradation and eventually activates pathways associated with the cell cycle and epithelial-mesenchymal transition (EMT). Together, these results indicate that the RASSF6-TRIM16 axis is a key effector in ESCC progression and that RASSF6 serves as a potential target for the treatment of ESCC.

MiR-496 promotes migration and epithelial-mesenchymal transition by targeting RASSF6 in colorectal cancer

Aberrant loss of tumor-suppressor genes plays a crucial role in tumorigenesis and development of colorectal cancer (CRC). Extensive studies have reported tha hypermethylation of Ras association domain family member 6 (RASSF6) is common in various solid tumors. Another important mode of epigenetic regulation, microRNA (miRNA) regulation of RASSF6, is far from clear. The aim of the present work was to screen out novel miRNA regulating RASSF6, and to explore its underlying mechanism in CRC. With the use of bioinformatics, clinical sample data, and luciferase binding assay, we determined that microRNA-496 (miR-496) could be a novel oncomiR that directly binds to RASSF6. Next, a series of miR-496 mimics or inhibitor, or RASSF6 small interfering RNA (siRNA) introduced into CRC cells were applied to examine the effect of miR-496 on CRC cell viability, migration, and epithelial-mesenchymal transition (EMT). The results demonstrated that miR-496/RASSF6 could promote cell migration and EMT via Wnt signaling activation, but had no effect on cell viability. Our results confirmed that the miR-496/RASSF6 axis is involved in Wnt pathway-mediated tumor metastasis, highlighting its potential as a therapeutic target for CRC.

Alteration of the tumor suppressor SARDH in sporadic colorectal cancer: A functional and transcriptome profiling-based study

Sporadic colorectal cancer (sCRC) is one of the leading causes of cancer death worldwide. As a highly heterogeneous complex disease, the currently reported classical genetic markers for sCRC, including APC, KRAS, BRAF, and TP53 gene mutations and epigenetic alterations, can explain only some sCRC patients. Here, we first reported a deleterious c.551C>T mutation in SARDH in sCRC. SARDH was identified as a novel tumor suppressor gene and was abnormally decreased in sCRC at both the transcriptional and the translational level. SARDH mRNA levels were also down-regulated in oesophageal cancer, lung cancer, liver cancer, and pancreatic cancer in the TCGA database. SARDH overexpression inhibited the proliferation, migration, and invasion of CRC cell lines, whereas its depletion improved these processes. SARDH overexpression was down-regulated in multiple pathways, especially in the chemokine pathway. The SARDH transcript level was positively correlated with the methylation states of CXCL1 and CCL20. Therefore, we concluded that SARDH depletion is involved in the development of sCRC.

Alteration of tumor suppressor BMP5 in sporadic colorectal cancer: a genomic and transcriptomic profiling based study

Background

Although the genetic spectrum of human colorectal cancer (CRC) is mainly characterized by APC, KRAS and TP53 mutations, driver genes in tumor initiation have not been conclusively demonstrated. In this study, we aimed to identify novel markers for CRC.

Methods

We performed exome analysis of sporadic colorectal cancer (sCRC) coding regions to screen loss of function (LoF) mutation genes, and carried out systems-level approaches to confirm top rank gene in this study.

Results

We identified loss of BMP5 is an early event in CRC. Deep sequencing identified BMP5 was mutated in 7.7% (8/104) of sCRC samples, with 37.5% truncating mutation frequency. Notably, BMP5 negative expression and its prognostic value is uniquely significant in sCRC but not in other tumor types. Furthermore, BMP5 expression was positively correlated with E-cadherin in CRC patients and its dysregulation play a vital role in epithelial-mesenchymal transition (EMT), thus triggering tumor initiation and development. RNA sequencing identified, independent of BMP/Smads pathway, BMP5 signaled though Jak-Stat pathways to inhibit the activation of oncogene EPSTI1.

Conclusions

Our result support a novel concept that the importance of BMP5 in sCRC. The tumor suppressor role of BMP5 highlights its crucial role in CRC initiation and development.

Electronic supplementary material

The online version of this article (10.1186/s12943-018-0925-7) contains supplementary material, which is available to authorized users.

Downregulation of lncRNA CASC2 facilitates osteosarcoma growth and invasion through miR-181a

OBJECTIVES

Long non-coding RNA cancer susceptibility candidate 2 (CASC2) is a novel lncRNA and has been indicated as playing tumour suppressor gene in several tumours. However, the role of CASC2 in osteosarcoma is still uncovered.

MATERIALS AND METHODS

The CASC2 and miR-181a expressions were measured via qRT-PCR. CCK-8 assay and colony formation assay were performed to determine the cell growth, and transwell assay was performed to assess the cell invasion.

RESULTS

We showed that CASC2 expression was downregulated in osteosarcoma samples and cell lines. Moreover, we showed that downregulated expression of CASC2 was correlated with advanced TNM stage. Furthermore, overexpression of CASC2 inhibited osteosarcoma cell proliferation, colony formation, and invasion. In addition, we indicated that ectopic expression of CASC2 suppressed miR-181a expression and enhanced the expression of Ras association domain family member 6 (RASSF6), PTEN and ATM in osteosarcoma cell, which were the direct target gene of miR-181a. Moreover, we indicated that RASSF6 expression was downregulated in osteosarcoma samples and cell lines and downregulated expression of RASSF6 was correlated with advanced TNM stage. We found that the expression of RASSF6 was positively correlated with the expression of CASC2 in osteosarcoma tissues. Ectopic expression of CASC2 suppressed the osteosarcoma cell proliferation, colony formation and invasion through regulating RASSF6 expression.

CONCLUSIONS

Our data illuminated that CASC2 acted as a tumour suppressor in osteosarcoma progression.

BCL-XL binds and antagonizes RASSF6 tumor suppressor to suppress p53 expression

RASSF6, a member of the tumor suppressor Ras-association domain family proteins, induces apoptosis in the caspase-dependent and caspase-independent manners. RASSF6 interacts with MDM2 and stabilizes p53. BCL-XL is a prosurvival member of BCL-2 family proteins. BCL-XL directly inhibits proapoptotic BAX and BAK. BCL-XL also traps tBID, a proapoptotic activator BH3-only protein, and sequesters p53. In addition, BCL-XL regulates the mitochondrial membrane permeability via voltage-dependent anion channel. In these manners, BCL-XL plays an antiapoptotic role. We report the interaction of BCL-XL with RASSF6. BCL-XL inhibits the interaction between RASSF6 and MDM2 and suppresses p53 expression. Consequently, BCL-XL antagonizes RASSF6-mediated apoptosis. Thus, the inhibition of RASSF6-mediated apoptosis also underlies the prosurvival role of BCL-XL.

RASSF6 downregulation promotes the epithelial-mesenchymal transition and predicts poor prognosis in colorectal cancer

Distant metastasis is the primary barrier for the successful treatment of patients with colorectal cancer, and thus, searching for new therapeutic targets by further exploring the molecular mechanisms of colorectal cancer metastasis is important. In this study, we investigated the biological and clinical significance of RASSF6 in colorectal cancer as well as the underlying molecular mechanisms. We found that low RASSF6 expression corresponds to a poor prognosis in colorectal cancer patients, and low RASSF6 expression is distinctly associated with tumour progression. Our in vitro analysis revealed that RASSF6 suppresses the proliferation and metastasis of DLD1 cells, and RASSF6 knockdown in HCT116 cells confirmed these observations. Our mechanistic investigation revealed that RASSF6 inhibits the expression of the classical target genes of Wnt signalling, as demonstrated by the reduced expression of TCF1, c-Jun, and c-Myc in RASSF6-overexpressing DLD1 stable cell lines. Furthermore, we show that RASSF6 functions as a negative regulator of the epithelial-mesenchymal transition; the expression levels of the epithelial markers ZO-1 and E-cadherin were increased, while the expression level of the mesenchymal marker Snail was decreased in a RASSF6-overexpressing DLD1 cell line. Additionally, rescue assays revealed that the activation of Wnt signalling by LiCl treatment impaired the inhibitory effect of RASSF6 on the proliferation and metastasis of colorectal cancer cells, which implies that RASSF6 suppresses the tumorigenicity of colorectal cancer cells at least in part through inhibiting Wnt signalling pathway. Collectively, these findings provide new perspectives for the future study of RASSF6 as a therapeutic target for colorectal cancer.

Overexpression of RAS-Association Domain Family 6 (RASSF6) Inhibits Proliferation and Tumorigenesis in Hepatocellular Carcinoma Cells

Ras-association domain family 6 (RASSF6), a member of the RASSF family, is frequently downregulated in various types of cancer. However, the roles of RASSF6 in human hepatocellular carcinoma (HCC) are still unclear. In this study, we investigated the biological functions and related molecular mechanisms in HCC. Our results found that RASSF6 is expressed in low amounts in HCC tissues and cell lines. Overexpression of RASSF6 obviously inhibited the proliferation, invasion, and EMT process in HCC cells. Furthermore, overexpression of RASFF6 greatly downregulated the protein levels of phosphorylated focal adhesion kinase (FAK), MMP-2, and MMP-9 in HepG2 cells. Last, overexpression of RASFF6 significantly attenuated tumor growth in Balb/c nude mice. In conclusion, the present study revealed that RASFF6 can inhibit the proliferation, invasion, and migration of HCC cells both in vivo and in vitro. These inhibitory effects are through suppressing FAK phosphorylation, leading to decreased MMP-2/9 expression. RASFF6 is therefore a potential therapeutic target for treating HCC.

Expression and purification of rhIL-10-RGD from Escherichia coli as a potential wound healing agent

Various protocols for recombinant Interleukin-10 (IL-10) purification in wound healing have been reported previously. However, the therapeutic effect was not obvious. Thus, it is of great importance to find new and effective approaches for therapy. In this study, we propose that IL-10 and Arginine-Glycine-Aspartic (RGD) peptide would be a valuable therapeutic for wound healing. To explore a high-efficiency and cost-effective approach for the production of IL-10 and RGD peptide with bioactivity, a synthetic gene was cloned into a recombinant pTWIN1 vector. As a consequence, rhIL-10-RGD and the pH-induced self-cleavable Ssp DnaB mini-intein as a fusion protein was highly expressed by IPTG induction in Escherichia coli Rosetta without extra residues in a bioreactor. After Ni affinity chromatographic purification, rhIL-10-RGD was released by the Ssp DnaB intein-mediated self-cleavage that is triggered by pH shift. SDS-PAGE and silver staining showed a major band with an estimated molecular mass of 19.3kDa. Cell proliferation assay confirmed its potent proliferation activity on MC/9 murine mast cells. In conclusion, we report a novel strategy to produce rhIL-10-RGD mediated by the pH-induced self-cleavable Ssp DnaB mini-intein, and show that rhIL-10-RGD could play an effective role in wound healing of BALB/c mice.