CircAGO2 promotes colorectal cancer progression by inhibiting heat shock protein family B (small) member 8 via miR-1-3p/retinoblastoma binding protein 4 axis.

This paper was to uncover the mechanism of circular RNA Argonaute 2 (circAGO2) in colorectal cancer (CRC) progression. The expression of circAGO2 was detected in CRC cells and tissues, and the relationship between clinicopathological features of CRC and circAGO2 level was evaluated. The growth and invasion of CRC cells and subcutaneous xenograft of nude mice were measured to evaluate the effect of circAGO2 on CRC development. Bioinformatics databases were applied to analyze levels of retinoblastoma binding protein 4 (RBBP4) and heat shock protein family B 8 (HSPB8) in cancer tissues. The relevance of circAGO2 and RBBP4 expression and the relationship between RBBP4 and HSPB8 during histone acetylation were assessed. The targeting relationship between miR-1-3p and circAGO2 or RBBP4 was predicted and confirmed. The effects of miR-1-3p and RBBP4 on biological functions of CRC cells were also verified. CircAGO2 was upregulated in CRC. CircAGO2 promoted the growth and invasion of CRC cells. CircAGO2 competitively bound to miR-1-3p and regulated RBBP4 expression, thus inhibiting HSPB8 transcription by promoting histone deacetylation. Silencing circAGO2 enhanced miR-1-3p expression and reduced RBBP4 expression, while suppression of miR-1-3p downgraded levels of miR-1-3p, up-regulated RBBP4, and facilitated cell proliferation and invasion in the presence of silencing circAGO2. RBBP4 silencing decreased RBBP4 expression and reduced proliferation and invasion of cells where circAGO2 and miR-1-3p were silenced. CircAGO2 overexpression decoyed miR-1-3p to increase RBBP4 expression, which inhibited HSPB8 transcription via histone deacetylation in HSPB8 promoter region, promoting proliferation and invasion of CRC cells.

miR-188-5p promotes oxaliplatin resistance by targeting RASA1 in colon cancer cells.

The efficacy of chemotherapy for colon cancer is limited due to the development of chemoresistance. MicroRNA (miR)-188-5p is downregulated in various types of cancer. The aim of the present study was to explore the molecular role of miR-188 in oxaliplatin (OXA) resistance. An OXA-resistant colon cancer cell line, SW480/OXA, was used to examine the effects of miR-188-5p on the sensitivity of colon cancer cells to OXA. The target of miR-188-5p was identified using a luciferase assay. Cell cycle distribution was also assessed using flow cytometry. The measurement of p21 protein expression, Hoechst 33342 staining and Annexin V/propidium iodide staining was used to evaluate apoptosis. The expression of miR-188-5p significantly increased in SW480/OXA compared with wild-type SW480 cells. The luciferase assay demonstrated that miR-188-5p inhibited Ras GTPase-activating protein 1 (RASA1; also known as p120/RasGAP) luciferase activity by binding to the 3'-untranslated region of RASA1 mRNA, suggesting that miR-188-5p could target RASA1. In addition, miR-188-5p downregulation or RASA1 overexpression promoted the chemosensitivity of SW480/OXA, as evidenced by increased apoptosis and G1/S cell cycle arrest. Moreover, RASA1 silencing abrogated the increase in cell apoptosis induced by the miR-188-5p inhibitor. The findings of the present study suggested that miR-188-5p could enhance colon cancer cell chemosensitivity by promoting the expression of RASA1.

Bone Morphogenetic Protein 1 Targeting COL1A1 and COL1A2 to Regulate the Epithelial-Mesenchymal Transition Process of Colon Cancer SW620 Cells.

Epithelial-mesenchymal transition (EMT) is an important factor in promoting the metastasis of colon cancer, which leads to clinical incurability. It has been found that bone morphogenetic proteins (BMPs) are closely related to EMT and the prognoses of most malignant tumors, including colon cancer tumors. However, the effects and mechanisms of BMP1 on the EMT of colon cancer are not yet clear. To explore the effects and mechanisms of BMP1 on the EMT of colon cancer, a BMP1 overexpression plasmid vector was used to interfere with SW620 cells and real-time fluorescence quantitative RNA and western blotting were used to detect the effects of BMP1 on the transcription and translation of COL1A1 and COL1A2 genes, as well as EMT-related genes, including beta-catenin, vimentin, and E-cadherin (E-Cad) genes in SW620 cells. MTT assay and Transwell techniques were used to detect the effects of BMP1 on the proliferation and migration of SW620 cells. The results demonstrate that BMP1 expression in SW620 cells is significantly lower than that in HCoEpiC cells, which promotes the expression of COL1A1 and COL1A2. Additionally, the expression of genes related to EMT, including beta-catenin and vimentin, increased, whereas E-Cad expression decreased. This difference was significant, which led to an increase in cell viability and the number of migrating cells in SW620 cells. Based on the overexpression of BMP1, the expression of COL1A1 and COL1A2 in SW620 was inhibited, which inhibited the process of EMT. Specifically, vimentin expression decreased, and E-Cad and beta-catenin expression increased. Additionally, SW620 cell viability decreased and migration ability decreased. Therefore, it can be concluded that the absence of BMP1 promotes the expression of COL1A and COL1A2 in colon cancer and promotes the process of EMT. Increasing the expression of BMP1 can inhibit the process of EMT in colon cancer, thereby inhibiting the migration of tumors.

Knockdown of PARP6 or survivin promotes cell apoptosis and inhibits cell invasion of colorectal adenocarcinoma cells.

Colorectal adenocarcinoma is the third most common cancer worldwide. PARP6, a novel member of the poly(ADP-ribose) polymerases (PARPs) and survivin, a member of the family of inhibitor of apoptosis (IAP) proteins are associated with a poor prognosis in various types of cancers. However, limited evidence exists regarding the interaction between PARP6 and survivin in colorectal adenocarcinoma. In the present study, we used the paired samples of 20 patients with colorectal adenocarcinoma to detect the expression of PARP6 and survivin in both tumor and adjacent normal colorectal mucosa. Their interaction and roles in cell viability, cell cycle, cell apoptosis and cell invasion were further investigated. Our results showed that both PARP6 and survivin exhibited higher expression in colorectal adenocarcinoma tissues and SW620 cells when compared with levels in adjacent non-tumor tissues and a normal colon cell line FHC. Co-immunoprecipitation assay showed that a significant correlation existed between PARP6 and survivin. We also showed that sole treatment of PARP6 siRNA or survivin siRNA partially inhibited the cell survival and invasion, induced cell G0/G1 arrest, and cell apoptosis at the early and late stages. The combined treatment of PARP6 siRNA and survivin siRNA suppressed the cell survival and cell invasion, further induced cell cycle phase G0/G1 arrest, and cell apoptosis at the early and late stages. Taken together, knockdown of PARP6 or survivin promotes cell apoptosis and inhibits the cell invasion of colorectal adenocarcinoma cells. A significant correlation exists between PARP6 and survivin, and both are promising targets for the development of new strategies for the diagnosis and treatment of advanced or metastatic colorectal adenocarcinoma.

Abrogation of MUC5AC Expression Contributes to the Apoptosis and Cell Cycle Arrest of Colon Cancer Cells.

Deregulated expressions of mucins have been found in various malignancies and play a pivotal role in carcinogenesis. MUC5AC, as a secreted mucin, is reported to be aberrantly expressed during epithelial cancer progression, including colon cancer. However, the mechanisms of the oncoprotein MUC5AC in the initiation of colon cancer requires further investigation. Here, we collected colon cancer tissues (n = 20) and corresponding paracancerous tissues (n = 20) and found that the expression of MUC5AC was significantly elevated in colon cancer tissues when compared with the corresponding paracancerous tissues. Immunofluorescence indicated that all colon cancer cell lines, including HT29, SW620, and the normal human intestinal epithelial cells FHC, showed the positive expression of MUC5AC, and SW620 exhibited the highest expression. Moreover, knockdown of MUC5AC in SW620 cells remarkably suppressed cell vitality and promoted apoptosis and G1 cell cycle arrest, resulting in the impaired ability of colony formation. Furthermore, the inhibition of MUC5AC in SW620 cells dramatically repressed the cell migration and invasion. These results demonstrated that MUC5AC as an oncogene could be a promising target in the treatment of colon cancer.