Transcriptional switches in the control of macronutrient metabolism

Metabolic Switch in the Tumor Microenvironment Determines Immune Responses to Anti-cancer Therapy

Tumor-induced immune tolerance permits growth and spread of malignant cells. Cancer cells have strong influence on surrounding cells and shape the hypoxic tumor microenvironment (TME) facilitating cancer progression. A dynamic change in glucose metabolism occurring in cancer cells and its influence on the TME are still poorly understood. Indeed, cancer and/or immune cells undergo rapid adaptation in metabolic pathways during cancer progression. Metabolic reprograming affects macrophages, T cells, and myeloid derived suppressor cells (MDSCs) among other immune cells. Their role in the TME depends on a nature and concentration of factors, such as cytokines, reactive oxygen species (ROS), growth factors, and most importantly, diffusible metabolites (i.e., lactate). Further, the amounts of available nutrients and oxygen as well as activity of microbiota may influence metabolic pathways in the TME. The roles of metabolites in regulating of the interaction between immune and cancer cell are highlighted in this review. Targeting metabolic reprogramming or signaling pathways controlling cell metabolism in the TME might be a potential strategy for anti-cancer therapy alone or in combination with current immunotherapies.

Dietary type and amount of fat modulate lipid metabolism gene expression in liver and in adipose tissue in high-fat diet-fed rats

BACKGROUND AND AIMS

Dietary fat plays a central role in the development of obesity. However, the metabolic consequences of dietary fat can vary depending on their fatty acid composition. Therefore, the aim of the present work was to study the effect of the type and amount of dietary fat on the expression of genes controlling lipogenesis and fatty acid oxidation in the liver or adipose tissue of rats.

METHODS

The expression of hepatic or adipose tissue lipid metabolic genes from Sprague Dawley or Zucker(fa/fa) rats, respectively, was measured after chronic consumption of diets containing different types/amounts of dietary fats or after rats were adapted for 2 months to a high-fat Western diet and then fed different types and amounts of fats.

RESULTS

Each fat or oil in the diet regulated differentially the expression of transcription factors involved in lipogenesis and fatty acid oxidation as well as some of its target genes in liver. The expression of these genes after a chronic consumption of a high-fat Western diet was reestablished in the presence of less dietary fat and was dependent on the type of fat. In obese Zucker(fa/fa) rats, consumption of a high-fat diet repressed the expression of lipogenic, fatty acid oxidation and thermogenic genes in adipose tissue.

CONCLUSIONS

Type of fat influences the expression of genes that are involved in lipid metabolism in liver and adipose tissue, but this response is repressed when the amount of dietary fat is excessive, diminishing the differences between each type of fat.