Energy metabolism during anchorage-independence. Induction by osteopontin-c

Area of Science:

• Cell Biology
• Cancer Metabolism
• Molecular Oncology

Background:

• Anoikis, a form of programmed cell death, normally prevents epithelial cell detachment.
• Invasive cancer cells resist anoikis, contributing to metastasis and tumor progression.
• Osteopontin, a key protein, has splice variants influencing cancer cell behavior.

Purpose of the Study:

• To elucidate the metabolic mechanisms enabling cancer cells to resist anoikis.
• To investigate the role of osteopontin splice variants, particularly osteopontin-c, in promoting anchorage-independence.
• To identify the specific metabolic pathways upregulated by osteopontin-c signaling.

Main Methods:

• Analysis of osteopontin splice variants in invasive tumor cells.
• Metabolic flux analysis using labeled substrates (N-acetyl-L-cysteine, L-glutamate, glycerol).
• Investigation of ATP production via creatine and mitochondrial respiratory pathways.

Main Results:

• Osteopontin-c supports anchorage-independence by upregulating interconnected energy metabolism pathways.
• Glutathione, glutamine, and glutamate fuel the hexose monophosphate shunt and glycolysis, feeding the tricarboxylic acid cycle for ATP production.
• The glycerol phosphate shuttle and creatine synthesis (from glutamine/glycolysis) also contribute to ATP generation, with redox and glutamine dependency observed.
• Osteopontin-a and osteopontin-c synergize, with osteopontin-a increasing glucose and osteopontin-c utilizing it for energy.

Conclusions:

• Cancer cells employ a coordinated metabolic strategy involving osteopontin variants to resist anoikis.
• Upregulation of glycolysis, the hexose monophosphate shunt, and mitochondrial respiration generates ATP, supporting survival and invasion.
• Targeting these metabolic pathways presents a potential therapeutic strategy against metastatic cancer.