Gut microbiome-mediated monocytes promote liver metastasis.

The gut microbiome plays an important role in tumor growth by regulating immune cell function. However, the role of the gut microbiome-mediated monocytes in liver metastasis remains unclear. In this study, we found that fecal microbiome transplantation (FMT) from the stool of patients with liver metastasis (LM) significantly promoted liver metastasis compared with healthy donors (HD). Monocytes were upregulated in liver tissues by the CCL2/CCR2 axis in LM patients' stool transplanted mouse model. CCL2/CCR2 inhibition and monocyte depletion significantly suppress liver metastasis. FMT using LM patients' stool enhanced the plasma lipopolysaccharides (LPS) concentration. The LPS/TLR4 signaling pathway is crucial for gut microbiome-mediated liver metastasis. These results indicated that monocytes contribute to liver metastasis via the CCL2/CCR2 axis.

Engineered multitargeting exosomes carrying miR-323a-3p for CRC therapy.

Colorectal cancer (CRC) is in the forefront of malignancies for its high incidence and mortality. 5-Fluorouracil (5-FU) is one of the most widely used effective drugs for the treatment of CRC. However, there is an urgent need in reducing its systemic side effects and chemoresistance, in order to make 5-FU-based chemotherapy more effective in the treatment of CRC. In this study, engineered CRC cells were established to overexpress miR-323a-3p, which was a tumor suppressor that targeted both EGFR and TYMS. Then miR-323a-3p-loaded exosomes (miR-Exo) were obtained with suitable methods of collection and purification. We found that miR-Exo significantly inhibited CRC cell proliferation and induced apoptosis by the way of targeting EGFR directly in the cells, which eventually led to desirable tumor regression in the cell derived xenograft (CDX) and patient derived xenograft (PDX) tumor mice models. Moreover, we discovered that miR-323a-3p released from miR-Exo directly inhibited the upregulation of thymidylate synthase (TYMS) induced by 5-FU-resistence in CRC cells, resulting in the revival of tumor cytotoxicity from 5-FU. MiR-Exo could effectively induce the CRC cell apoptosis by targeting EGFR and TYMS, and enhance the therapeutic effects of 5-FU on CRC. Our work demonstrates the potency of miR-Exo for advanced CRC biotherapy.

The lncRNA SCARNA2 mediates colorectal cancer chemoresistance through a conserved microRNA-342-3p target sequence.

Long noncoding RNAs (lncRNAs) have been implicated in numerous physiological and pathological processes, including cancer development and progression. However, the role and molecular mechanism of lncRNAs in resistance to chemotherapy of colorectal cancer (CRC) remain enigmatic. Here, we found that lncRNA small Cajal body-specific RNA 2 (SCARNA2) is expressed higher in CRC tissues than in adjacent normal tissues, and a robust expression of SCARNA2 is correlated with a bad prognosis of CRC patients after surgery. SCARNA2 overexpression significantly promoted chemoresistance in CRC cells, and downregulation of SCARNA2 obviously inhibited chemoresistance in vitro. SCARNA2 promotes chemotherapy resistance via competitively binding miR-342-3p to facilitate epidermal growth factor receptor (EGFR) and B-cell lymphoma 2 (BCL2) expression in CRC cells. Together, our results reveal a novel pathway that SCARNA2 regulates CRC chemoresistance through targeting miR-342-3p-EGFR/BCL2 pathway, providing a promising therapeutic target for CRC.

Quantitative analysis of APC promoter methylation in hepatocellular carcinoma and its prognostic implications.

The present study aimed to quantitatively determine the aberrant methylation signal of the adenomatous polyposis coli (APC) gene in hepatocellular carcinoma (HCC), and to evaluate whether hypermethylation of the APC promoter could be a prognostic biomarker for HCC. Taqman probe-based quantitative methylation-specific polymerase chain reaction was performed to identify the APC promoter methylation levels in 57 HCC and corresponding non-tumorous liver tissues. In the present study, the methylation level of the APC promoter was upregulated by 4.51-fold in the HCC tissues compared with the non-cancerous tissues (P=0.0003). With regard to the clinicopathological data, the methylation level of the APC promoter in the HCC samples was higher in the patients with larger tumors when the cut-off was set at 4 cm (P=0.0008), and in the older patients when the cut-off was set at 60 years old (P=0.0438). However, the methylation status in the HCC samples appeared not to affect the overall patient survival rate (P=0.1684). The findings of the present study showed that APC promoter hypermethylation accumulates during the development of HCC, but that it may not be a promising prognostic biomarker for HCC.

Hypermethylation leads to bone morphogenetic protein 6 downregulation in hepatocellular carcinoma.

BACKGROUND: In the liver, bone morphogenetic protein 6 (BMP-6) maintains balanced iron metabolism. However, the mechanism that underlies greater BMP-6 expression in hepatocellular carcinoma (HCC) tissue than adjacent non-cancerous tissue is unclear. This study sought to investigate the epigenetic mechanisms of BMP-6 expression by analysing the relationship between the DNA methylation status of BMP-6 and the expression of BMP-6. METHODS: Methylation-specific polymerase chain reaction (PCR), bisulphite sequencing PCR, the MethyLight assay, and quantitative real-time PCR were performed to examine BMP-6 methylation and mRNA expression levels. Immunohistochemistry (IHC) was performed on tissue arrays to evaluate the BMP-6 protein level. RESULTS: BMP-6 mRNA expression was approximately 84.09% lower in HCC tissues than in adjacent non-cancerous tissues, and this low level of expression was associated with a poor prognosis. Moreover, the hypermethylation observed in HCC cell lines and HCC tissues was correlated with the BMP-6 mRNA expression level, and this correlation was validated following treatment with 5-aza-CdR, a demethylation agent. In addition, BMP-6 DNA methylation was upregulated by 68.42% in 114 clinical HCC tissue samples compared to adjacent normal tissues, whereas the BMP-6 staining intensity was downregulated by 77.03% in 75 clinical HCC tissue samples in comparison to adjacent normal tissues. Furthermore, elevated expression of BMP-6 in HCC cell lines inhibited cell colony formation. CONCLUSIONS: Our results suggest that BMP-6 CpG island hypermethylation leads to decreased BMP-6 expression in HCC tissues.

Quantitative analysis of RASSF1A promoter methylation in hepatocellular carcinoma and its prognostic implications.

Hepatocellular carcinoma (HCC) is one of the most common malignant tumors worldwide and is caused by the accumulation of genetic and epigenetic alterations in regulatory genes. In this study, we used methylight to detect the methylation status of the RASSF1A promoter in 87 paired HCC samples and analysed the relationship between methylation status and clinicopathological parameters, including prognosis after surgery. We found that the methylation level of the RASSF1A promoter in HCC tissues was significantly higher than that in the corresponding non-tumorous tissues (p<0.0001). Furthermore, the methylation level of the RASSF1A gene promoter in HCC samples was higher in patients with a tumor size ≥ 6cm (p=0.0149) and in patients younger than 50 years old (p=0.0175). However, hypermethylation of the RASSF1A promoter in HCC tissues did not affect the overall survival of patients (p=0.611). Thus, RASSF1A promoter hypermethylation may not be a useful biomarker for the prognosis of HCC.