Lipid droplets: could they be involved in cancer growth and cancer–microenvironment communications?

Common characteristics of tumor cells include the reprogramming of glucose and lipid metabolism, especially the upregulation of glycolysis and lipogenesis accompanied by the accumulation of lipid droplets (LDs) predominantly in aggressive cancer cells and their microenvironment, such as the cancer cells and microenvironment in Zajdela ascites hepatoma (ZAH) [1, 2]. This work analyzed the hypothesis that LD-rich malignant cells gain an advantage for their survival, growth, and immune escape through cancer-derived LDs actingwithinmalignant cells and their microenvironment in a synergistic manner. The effect can be amplified at hypoxia/acidosis in the tumor microenvironment, which stimulates mainly the accumulation of dispersed LDs in tumor cells [3, 4]. Our research, however, found that intracellular LDs and their orderly packed clusters appeared in dividing ZAH cells, whereas surface LD-containing vesicles in ZAH cells acted as a source of extracellular LDs. Could these LDs be involved in cancer unrestricted proliferation and cancer-induced metabolic communications with a microenvironment participating in local immunosuppressive response? Critical analysis of the literature supports a positive answer to these questions and to the proposed hypothesis.