Efficacy of the MEK Inhibitor Cobimetinib and its Potential Application to Colorectal Cancer Cells

Abstract

Background/Aims: Mutations in the Ras/Raf/MEK/ERK pathway are detected in 50% of colorectal cancer cases and play a crucial role in cancer development and progression. Cobimetinib is a MEK inhibitor approved for the treatment of advanced melanoma and inhibits the cell viability of other types of cancer cells. Methods: HCT116 colorectal cancer cells were treated with cobimetinib, and MTT assay, colony formation assay, and flow cytometry were used to evaluate cell viability, cell cycle, and apoptosis, respectively. The expression of genes associated with the cell cycle and apoptosis were evaluated by quantitative real-time PCR and western blotting. To explore use of cobimetinib in colorectal cancer treatment and further understand its mechanisms, RNA-seq technology was used to identify differentially expressed genes (DEGs) between cobimetinib-treated and untreated HCT116 cells. Furthermore, we compared these DEGs with Gene Expression Omnibus data from colorectal cancer tissues and normal colonic epithelial tissues. Results: We found that cobimetinib not only inhibited cell proliferation but also induced G1 phase arrest and apoptosis in HCT116 colorectal cancer cells, suggesting that cobimetinib may useful in colorectal cancer therapy. After cobimetinib treatment, 3,495 DEGs were obtained, including 2,089 upregulated genes and 1,406 downregulated genes, and most of these DEGs were enriched in the cell cycle, DNA replication, and DNA damage repair pathways. Our results revealed that some genes with high expression in colorectal cancer tissues were downregulated by cobimetinib in HCT116 cells, including CCND1, E2F1, CDC25C, CCNE2, MYC, and PCNA. These genes have vital roles in DNA replication and the cell cycle. Furthermore, genes with low expression in colorectal cancer tissues were upregulated by cobimetinib, including PRKCA, PI3K, RTK, and PKC. Based on our results, the PKC and PI3K pathways were activated after cobimetinib treatment, and inhibition of these two pathways can increase the cytotoxicity of cobimetinib in HCT116 cells. Notably, cobimetinib appeared to enhance the efficacy of 5-fluorouracil (5-FU) by decreasing TYMS expression, high expression of which is responsible for 5-FU resistance in colorectal cancer. Conclusions: Our results suggest the potential use of cobimetinib in colorectal cancer therapy.

m6A methyltransferase METTL3 maintains colon cancer tumorigenicity by suppressing SOCS2 to promote cell proliferation

“…Given the potential function of METTL3 in regulating cell proliferation implied by the above bioinformatic analysis results, we screened the differential expression profiles of proliferation-related genes in METTL3-KO SW480 cells vs. the control SW480 (SW480 WT) cells to determine whether downregulation of METTL3 modulates cell proliferation in CRC. Ki67, LGR5, PCNA, SOX2 and Cyclin B1 have been reported to be positively correlated with cell proliferation ( 33 – 36 ). All five of these genes were significantly downregulated in the METTL3-KO SW480 cells.…”

Signaling pathway network alterations in human ovarian cancers identified with quantitative mitochondrial proteomics

“…Other proteins, including HLA-A, HLA-DMA, HLA-DQA1, HLA-DQB1, HLA-DRA, HLA-DRB1, and HLA-DRB5, were not reported on tumor–host immunological interactions, which indicated the proteins need further studies to testify them as novel OC biomarkers for tumor immunology. CAPN2, ITPR1, PPP3CA, and PRKCA were enriched in calcium-induced T lymphocyte apoptosis pathway, and not reported on tumor-host immunological interactions, but those proteins were repeatedly reported relevant to human cancers [ 36 ]. It remains unknown whether those molecules influence development of carcinomas by immune system.…”

Overexpression of sortilin is associated with 5‐FU resistance and poor prognosis in colorectal cancer

“…Consequently, classic pro‐survival signalling pathways implicated in carcinogenesis (PI3K/Akt and Erk1/2) are affected. Both Pi3K/Akt and Ras/Raf/mitogen‐activated protein kinases (MAPK) are inter‐connected pro‐survival pathways associated with cell proliferation and prevention of apoptosis, 53,54 which have been demonstrated to be involved in CRC cell 5‐FU resistance: Erk1/2 and PI3K/Akt pathways’ inhibition enhances 5‐FU cytotoxicity and apoptosis in CRC cells, 55‐58 reinforcing the benefit of targeting proliferative pathways in association with chemotherapy. Even though no difference in BRAF or KRAS mutational status between 5‐FU‐resistant and ‐untreated CRC cells was observed (data not shown), analysis of other genes might be interesting.…”

“…For example, PTEN ‐activating and/or PI3KCA ‐inhibitory mutations could explain the Akt inhibition observed in 5‐FU‐resistant CRC cells 54 . Because Akt hyperactivation in pancreatic cancer cells results in subsequent inhibition of Raf and mitogen‐activated protein kinase kinase (MEK)/Erk1/2 pathway, 54 and that MEK1/2 inhibition results in PI3K/Akt pathway activation in CRC cells, 56 these two pathways take over from each other. In fact, the Akt activation observed in 5‐FU‐resistant CRC cells from low tumour grade cells (WiDr) could be consistent with the no significant Erk modification; and the Akt inhibition observed in 5‐FU‐resistant CRC cells from high tumour grade cells (SW620) could be consistent with increased Erk activation.…”