M 4 IDP stimulates ROS elevation through inhibition of mevalonate pathway and pentose phosphate pathway to inhibit colon cancer cells.

Maintaining redox homeostasis is an essential feature of cancer cells, and disrupting this homeostasis to cause oxidative stress and induce cell death is an important strategy in cancer therapy. M ₄ IDP, a zoledronic acid derivative, can cause the death of human colorectal cancer cells by increasing the level of intracellular reactive oxygen species (ROS). However, its potential molecular mechanism is unclear. Our in vitro studies showed that treatment with M ₄ IDP promoted oxidative stress in HCT116 cells, as measured by the decreased ratios of GSH/GSSG and NADPH/NADP ⁺ and increased level of MDA. M ₄ IDP could cause the decrease of GSH content, the increase of GSSG content, the decrease of NADPH content and pentose phosphate pathway flux, the downregulation of G6PD expression, the upregulation of unprenylated Rap1A and total expression of RhoA and CDC42. The increase of ROS and cytotoxicity induced by M ₄ IDP could be reversed by the supplementation of NADPH, the overexpression of G6PD and the supplementation of GGOH. In vivo studies showed that M ₄ IDP inhibited tumor growth in the human colorectal cancer xenograft mouse model, which was accompanied with a decreased [ ¹⁸ F]FDG uptake. Collectively, these results provide evidence that M ₄ IDP can promote oxidation in colon cancer cells by inhibiting mevalonate pathway and pentose phosphate pathway and produce therapeutic effect. This study revealed for the first time a possible mechanism of bisphosphonate-induced increase of ROS in malignant tumor cells. This is helpful for the development of new molecular therapeutic targets and can provide new ideas for the combined therapy of bisphosphonates in tumors.
Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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