Role of abnormal lipid metabolism in development, progression, diagnosis and therapy of pancreatic cancer

Abstract

There is growing evidence that metabolic alterations play an important role in cancer development and progression. The metabolism of cancer cells is reprogrammed in order to support their rapid proliferation. Elevated fatty acid synthesis is one of the most important aberrations of cancer cell metabolism. An enhancement of fatty acids synthesis is required both for carcinogenesis and cancer cell survival, as inhibition of key lipogenic enzymes slows down the growth of tumor cells and impairs their survival. Based on the data that serum fatty acid synthase (FASN), also known as oncoantigen 519, is elevated in patients with certain types of cancer, its serum level was proposed as a marker of neoplasia. This review aims to demonstrate the changes in lipid metabolism and other metabolic processes associated with lipid metabolism in pancreatic ductal adenocarcinoma (PDAC), the most common pancreatic neoplasm, characterized by high mortality. We also addressed the influence of some oncogenic factors and tumor suppressors on pancreatic cancer cell metabolism. Additionally the review discusses the potential role of elevated lipid synthesis in diagnosis and treatment of pancreatic cancer. In particular, FASN is a viable candidate for indicator of pathologic state, marker of neoplasia, as well as, pharmacological treatment target in pancreatic cancer. Recent research showed that, in addition to lipogenesis, certain cancer cells can use fatty acids from circulation, derived from diet (chylomicrons), synthesized in liver, or released from adipose tissue for their growth. Thus, the interactions between de novo lipogenesis and uptake of fatty acids from circulation by PDAC cells require further investigation.

Keywords: Cyclooxygenase-2; Farnesylation; Fatty acid synthase; Hypoxia inducible factor 1α; Lipid metabolism; Lipogenic enzymes inhibitors; Monounsaturated fatty acids; Oncogenes; Pancreatic cancer; Tumor suppressors.

Figure 1

Cellular metabolism of cancer cells-association with cell proliferation. Solid arrows represent single reactions; dotted arrows represent processes including numerous reactions. PRPP: Phosphoribosyl pyrophosphate; Ribose 5-P: Ribose 5-phosphate; Glucose 6-P: Glucose 6-phosphate; PDH: Pyruvate dehydrogenase; CS: Citrate synthase; ACLY: ATP citrate lyase; HMG-CoA: 3-hydroxy-3-methylglutaryl-coenzyme A.

Figure 2

Hallmarks of cancer.

Figure 3

Glutamine metabolism of cancer cells. Red arrows represent glutaminolysis; green arrows represent “reversed Krebs cycle” reactions; blue arrows represent glycolysis; yellow arrows represent lipogenesis. Solid arrows represent single reactions; dotted arrows represent processes including numerous reactions. Fructose 6-P: Fructose 6-phosphate; GAGs: Glycosaminoglycans; GPs: Glycoproteins.

Figure 4

Role of hypoxia inducible factor 1 α'β in pancreatic cancer. HIF1α: Hypoxia inducible factor 1α; HIF1β: Hypoxia inducible factor 1β; VHL: Von Hippel-Lindau tumor suppressor; GLUT-1: Glucose transporter 1; LDH: Lactate dehydrogenase.

Figure 5

Fatty acid synthesis in pancreatic cancer. The up-regulated enzymes are marked in green. GLUT-1: Glucose transporter 1; HK: Hexokinase; glucose 6-P: Glucose 6-phosphate; PDH: Pyruvate dehydrogenase; CS: Citrate synthase; ACLY: ATP citrate lyase; ACCA: Acetyl-CoA carboxylase; FASN: Fatty acid synthase; ACS: Acyl-CoA synthetase, ELOV: Elongase; SCD: Stearoyl-CoA desaturase; PUFA: Polyunsaturated fatty acids; MUFA: Monounsaturated fatty acids; SFA: Saturated fatty acids.

Figure 6

Possible role of aldo-keto reductase 1B10 in regulation of cell proliferation in pancreatic cancer. Binding of AKR1B10 results in stabilization of ACCA, and up-regulation of fatty acid synthesis. AKR1B10: Aldo-keto reductase family 1B10; ACCA: Acetyl-CoA carboxylase; Isopentenyl-PP: Isopentenyl diphosphate; Geranyl-PP: Geranyl diphosphate; Farnesyl-PP: Farnesyl diphosphate; Geranylgeranyl-PP: Geranylgeranyl diphosphate.