The metabolic comparison between normal and lung cancer cell lines in the anoikis condition

Abstract

Lung cancer is a fatal disease with a low survival rate because it has little or no symptoms in the advanced stage. Further, it has the highest mortality, 22.6%, among all cancers in Korea. Generally, when normal cells lose their interaction with the matrix, it results in a phenomenon called anoikis as a defense mechanism of the living body, and the cells die. Tumors can be completely removed from the primary site without metastasis

therefore, cancer cells can survive, and this plays an important role in the early stages of cancer metastasis. Therefore, by studying the anoikis resistance of cancer cells, we can prevent cancer metastasis and improve the existing cancer treatment methods. In this study, we compared the difference between the metabolism of normal and cancer cells

further, we analyzed how cancer cells can be resistant to anoikis. First, we compared the cell viability of the lung cancer cell (A549) and the normal cell (MRC5) in the anoikis condition, establishing time points of 8 h, the time point when the cell survival rate starts to change, and 29 h, the time point that shows the most different survival rate. Using metabolic analyses, the ratio of GSH (reduced)/total glutathione in the normal cells dipped notably at 29 h. This indicates that normal cells die because they cannot overcome the increased oxidative stress. Furthermore, the 13C glucose flux data of the energy metabolites (e.g., ATP, CTP, etc.) using stable isotope labeling showed a significant reduction of M + 5 of energy metabolites, especially at 29 h in normal cells. The M + 5 labeling of ATP corresponded to the ribose ring with 13C glucose labeled. In other words, it was possible to deduce that some specific step of purine synthesis was down regulated from glucose to ATP. De novo purine biosynthetic enzyme PPAT was decreased in the normal cells using real-time PCR. In terms of cancer, pyruvate carboxylase (PC) of the cancer was significantly increased at 29 h than at 8 h in the anoikis condition. Moreover, the total amount of NADPH was higher in the cancer cells, indicating that it was actively using the pentose phosphate pathway (PPP). Consequently, it contributed to the survival of cancer cells under the anoikis condition. Studies have shown that metabolic differences between the normal and cancer cells might play an important role in anoikis resistance. This could provide a new perspective for future studies of metastasis and resistance to lung cancer.