TGF-β protects osteosarcoma cells from chemotherapeutic cytotoxicity in a SDH/HIF1α dependent manner

Abstract

Background In the widespread adoption of chemotherapy, drug resistance has been the major obstacle to tumor elimination in cancer patients. Our aim was to explore the role of TGF-β in osteosarcoma-associated chemoresistance. Methods We performed a cytotoxicity analysis of methotrexate (MTX) and cisplatin (CIS) in TGF-β-treated osteosarcoma cells. Then, the metabolite profile of the core metabolic energy pathways in Saos-2 and MG-63 cell extracts was analyzed by 1H-NMR. We detected the expression of succinate dehydrogenase (SDH), STAT1, and hypoxia-inducible factor 1α (HIF1α) in TGF-β-treated osteosarcoma cells and further tested the effects of these molecules on the cytotoxicity induced by chemotherapeutic agents. Using in vivo experiments, we examined the tumor growth and survival time of Saos-2-bearing mice treated with a combination of chemotherapeutic agents and a HIF1α inhibitor. Results The metabolic analysis revealed enhanced succinate production in osteosarcoma cells after TGF-β treatment. We further found a decrease in SDH expression and an increase in HIF1α expression in TGF-β-treated osteosarcoma cells. Consistently, blockade of SDH efficiently enhanced the resistance of Saos-2 and MG-63 cells to MTX and CIS. Additionally, a HIF1α inhibitor significantly strengthened the anticancer efficacy of the chemotherapeutic drugs in mice with osteosarcoma cancer. Conclusion Our study demonstrated that TGF-β attenuated the expression of SDH by reducing the transcription factor STAT1. The reduction in SDH then caused the upregulation of HIF1α, thereby rerouting glucose metabolism and aggravating chemoresistance in osteosarcoma cells. Linking tumor cell metabolism to the formation of chemotherapy resistance, our study may guide the development of additional treatments for osteosarcoma.

Metabolic reprogramming in osteosarcoma

“…Circ‐ECE1, Her4, and PDGFRβ increase glucose uptake and promote metabolic reprogramming in OS through cMyc 24–26 . MiR‐186, KRT17 and TGF‐β promote glucose uptake and glycolysis in OS cells via HIF‐1ɑ 27–29 . The miR‐200c plays a central role in glucose metabolism in cancer cells, and CircCSPP1 may influence miR‐200c maturation to regulate glucose uptake and cell proliferation to promote OS 30 .…”

“…Xu et al. found that reduced SDH expression in OS cells led to an accumulation of succinate, and TGF‐β reduced SDH expression by decreasing STAT1, leading to upregulation of HIF1α, which alters glucose metabolism and exacerbates chemoresistance in OS cells 29 . Ziemann and colleagues discovered that MiR‐101‐3p was a tumor suppressor that regulates mitochondrial metabolism of OS cells by regulating mtDNA transcription and complex II 128 …”

“…[24][25][26] MiR-186, KRT17 and TGF-β promote glucose uptake and glycolysis in OS cells via HIF-1ɑ. [27][28][29] The miR-200c plays a central role in glucose metabolism in cancer cells, and CircCSPP1 may influence miR-200c maturation to regulate glucose uptake and cell proliferation to promote OS. 30 By interfering with glucose uptake, glycolysis is influenced at the source, affecting OS cells' energy supply.…”

The roles of glycolysis in osteosarcoma

“…The regulation of glycolysis by TGF-β has also been reported in OS. TGF-β weakens succinate dehydrogenase (SDH) expression by reducing the transcription factor STAT1, which leads to the accumulation of succinate and the increase of HIF-1α in OS cells, then changes the glycolysis state and drug resistance of OS cells ( Xu et al, 2021 ). Moreover, TGF-β inhibitor RepSox inhibits OS proliferation and EMT and promotes apoptosis by inhibiting the JNK/Smad3 signal pathway ( He et al, 2021 ).…”

“…TGF-β negative transcription factor STAT1 further inhibited the expression of succinate dehydrogenase (SDH). The decrease of SDH leads to HIF-1α upregulation, which changes the metabolic level of glucose and the drug resistance of OS cells ( Xu et al, 2021 ). The miR-186 inhibits the proliferation, invasion, and glycolysis of OS cells by targeting HIF-1α and pituitary tumor transforming gene 1 (PTTG1) ( Xiao et al, 2018 ).…”