Glucose is an energy metabolite necessary for cellular survival and growth whether or not the cell is part of a tumor. Not only do cancer cells switch from oxidative phosphorylation to aerobic glycolysis (the Warburg effect) to gain more glucose, a hallmark of cancer, but they also increase the amount of glucose taken up from the surrounding extracellular space. However, the lack of glucose can have a negative effect on cells, causing them to become apoptotic in the absence of this metabolite. Cancer cells have methods to get around the requirement for glucose, including upregulating glucose transporters to improve access to the energy metabolite. In this Redox Biology article, researchers describe how activating androgen receptor in response to a lack of glucose affects the amount of GLUT1 expressed on prostate cancer cells, making the cells resistant to glucose deprivation.
To set the stage, two prostate cancer cell lines, LNCaP, an androgen-sensitive cell line, and LNCaP-R, an androgen-insensitive cell line, were deprived of glucose. Both cell lines showed signs of cell death, but LNCaP-R cells died in greater numbers. To probe how LNCaP cells died, several inhibitors (a pan-caspase inhibitor, two necroptosis inhibitors and a ferroptosis inhibitor) were added but did not change the way the cells died. However, an autophagy inhibitor enhanced cell death, suggesting the cells were necrotic not apoptotic. Teasing apart if the necrosis of LNCaP cells was due to glucose availability or merely disrupted glycolysis, the glucose analog 2DG was added to the medium with glucose. The cells survived when treated with 2DG, suggesting it was the absence of glucose that induced necrosis. When LNCaP cells were cultivated in medium that replaced glucose with mannose or fructose, the cells survived, another point in favor of sugar depletion causing cell death. Continue reading