Growth inhibitory effects of vitamin K2 on colon cancer cell lines via different types of cell death including autophagy and apoptosis

Abstract

Abstract. Vitamin K2 (menaquinone-4: MK4) has been reported to inhibit cell growth and induce apoptosis in various tumor cells. We examined the effects of MK4 using three types of colon cancer cell lines: PMCO1, COLO201, and DLD-1. Exposure to MK4 was at concentrations from 5 to 50 μM, growth inhibitory effects were observed dose-dependently in COLO201 and PMCO1, whereas the growth inhibition observed in DLD-1 was minimal. Comparison of COLO201 and PMCO1 cells exhibiting distinct growth inhibitory effects showed that cell death via apoptosis accompanied by activation of caspase-3 was induced in PMCO1, while apoptosis was not induced in COLO201. On the contrary, immunoblot assay using an anti-LC3B antibody showed autophagy induction by addition of MK4 and incubation in all three types of colon cancer cell lines. Addition of 3-methyladenine (3-MA) attenuated the growth inhibitory effect of MK4 in COLO201, whereas no influence of 3-MA was noted in PCMO1. Electron microscopy images of COLO201 showed that addition of MK4 induced an increased number of cytoplasmic autophagosomes and autolysosomes as well as morphological changes including scantiness of cytoplasm accompanied by loss of cell organelles, nuclear shrinkage, and fragmentation of cytoplasmic membrane in some cells, indicating the induction of cell death via autophagy not accompanied by the formation of apoptotic bodies in COLO201 cells. These results suggested that the response to MK4 and the way of induction of cell death vary in different colon cancer cell lines.

Identification of microbial markers across populations in early detection of colorectal cancer

“…2b ), and was the 3rd and 4th contributor to MK-10 biosynthesis in adenoma and cancer among all ASVs (Supplementary Data 14 ). Collectively, the elevated production of vitamin K2 by microbiota may serve as a response to compensate for the induction of feedback inhibition in colorectal cancer cells 29 . Furthermore, we found a significantly increased abundance of menH , menF, and menC in CRC samples compared with that of adenoma in pooled data sets by a two-sided blocked Wilcoxon rank-sum test (Supplementary Table 4 ).…”

“…Moreover, a series of vitamin K2 biosynthesis genes, such as menH and menF were also significantly different between adenoma and cancer. Previous studies indicated that vitamin K2 played important roles in the antitumor effect via cell-cycle arrest, cell differentiation, and cell apoptosis 29 . Therefore, the increased production of vitamin K2 may be a compensatory effect of the dysregulated microbiota to survive the tumor microenvironment, which also suggests a potential CRC intervention strategy targeting vitamin K2 biosynthesis bacteria.…”

Identification of microbial markers across populations in early detection of colorectal cancer

“…The ASV assigned as Bacteroides ranked the 3 rd and 4 th in contribution to MK-10 biosynthesis in adenoma and cancer among all ASVs (Supplementary Table 13). Collectively, the production of Vitamin K2 by microbiota may serve as a response to compensate for induction of feedback inhibition in colorectal cancer cells(28). We found a significantly increased abundance of menH, menF and menC in CRC samples compared with that of control in pooled datasets by blocked Wilcoxon test (Supplementary Table 12).…”

“…The increased abundance of menH in CRC samples activated the synthesis of this pathway. Previous studies indicated that Vitamin K2 played a key role in antitumor effect via cell-cycle arrest, cell differentiation and cell apoptosis(28). Therefore, the increased production of Vitamin K2 may be a compensatory effect of the dysregulated microbiota to survive the tumor microenvironment, which also shows a potential novel CRC intervention strategy targeting Vitamin K2 biosynthesis bacteria.…”