Metastatic cancer cells compensate for low energy supplies in hostile microenvironments with bioenergetic adaptation and metabolic reprogramming.

Metastasis accounts for the majority of cancer-related mortalities, and the complex processes of metastasis remain the least understood aspect of cancer biology. Metabolic reprogramming is associated with cancer cell survival and metastasis in a hostile envi-ronment with a limited nutrient supply, such as solid tumors. Little is known regarding the differences of bioenergetic adaptation between primary tumor cells and metastatic tumor cells in unfavorable microenvironments; to clarify these differences, the present study aimed to compare metabolic reprogramming of primary tumor cells and metastatic tumor cells. SW620 metastatic tumor cells exhibited stronger bioenergetic adaptation in unfavorable conditions compared with SW480 primary tumor-derived cells, as determined by the sustained elevation of glycolysis and regulation of the cell cycle. This remarkable glycolytic ability of SW620 cells was associated with high expression levels of hexokinase (HK)1, HK2, glucose transporter type 1 and hypoxia-inducible factor 1α. Compared with SW480 cells, the expression of cell cycle regulatory proteins was effectively inhibited in SW620 cells to sustain cell survival when there was a lack of energy. Furthermore, SW620 cells exhibited a stronger mesenchymal phenotype and stem cell characteristics compared with SW480 cells; CD133 and CD166 were highly expressed in SW620 cells, whereas expression was not detected in SW480 cells. These data may explain why metastatic cancer cells exhibit greater microenvironmental adaptability and survivability; specifically, this may be achieved by upregulating glycolysis, optimizing the cell cycle and reprogramming cell metabolism. The present study may provide a target metabolic pathway for cancer metastasis therapy.