Nianli Sang

Enhanced glutaminolysis and glycolysis are the two most remarkable biochemical features of cancer cell metabolism, reflecting increased utilization of glutamine and glucose in proliferating cells. Most solid tumors often outgrow the blood supply, resulting in a tumor microenvironment characterized by the depletion of glutamine, glucose, and oxygen. Whereas mechanisms by which cancer cells sense and metabolically adapt to hypoxia have been well characterized with a variety of cancer types, mechanisms by which different types of tumor cells respond to a dynamic change of glutamine availability and the underlying importance remains to be characterized. Here we describe the protocol, which uses cultured Hep3B cells as a model in determining glutamine-dependent proliferation, metabolite rescuing, and cellular responses to glutamine depletion. These protocols may be modified to study the metabolic roles of glutamine in other types of tumor or non-tumor cells as well.

Cancer cells consume large amount of glutamine which greatly exceeds the needs for direct use for protein translation and nucleotide synthesis. Independent studies have demonstrated that glutaminolysis driven by oncogenic signaling pathways accounts for this increased consumption. This article summarizes the direct and indirect metabolic roles of glutamine in cancer cell metabolism. In addition, we will discuss how oncogenic signaling pathways regulate glutamine utilization in cancers, and how cancer cells respond to glutamine depletion.