Human Cancer Cell

Cancer cells live in hypoxic, hypo-nutrient circumstances provided by insufficient angiogenesis due to fast rates of cancer cell proliferation. These circumstances lead cancer cells via production of ATP as energy sources mainly via high rate glycolysis, while most normal cells produce ATP via oxidation of pyruvate in mitochondria with relatively low-rate glycolysis compared with cancer cells. The high-rate glycolysis forming lactate produces a large amount of H+, providing acidic micro environments around cancer cells. Interestingly, cancer cells keep the cytosolic pH (pHc) slightly higher than that of normal cells even under these environmental conditions provided by a large amount of H+ due to high-rate glycolysis. From a viewpoint of cell cycle arrest, apoptosis and cell growth, pHc of tumor cells kept at a level slightly higher than that of normal cells is a key factor for prevention from cell cycle arrest and apoptosis even under acidic microenvironments around cancer cells. These findings clearly indicate that cancer cells have to maintain their pHc at a level slightly higher than that of normal cells for survival even under acidic conditions with production of a large amount of H+. For maintenance of pHc at a level slightly higher even under acidic environmental conditions than normal one, expression and/or activity of H+and/or HCO3-transporting systems in cancer cells would be expected to be higher than normal cells. Further, it is notable that cancer cells utilize a self-nutrient-recycling autophagy system for their survival even under starvation conditions. The self-nutrient-recycling autophagy occurs in lysosome, and the intralysosomal pH is much lower than the cytosolic one. Cl-also plays a key role in regulation of pHc and intra-lysosomal pH. In this article, I discuss roles of ionic circumstances in growth and lysosomal function in cancer cells.

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Last date updated on April, 2024