Pentose phosphate recycling driven by Gli1 contributes to chemotherapy resistance in cancer cells

The Hedgehog Signaling Pathway plays an important role in cancer development and chemotherapy resistance. However, whether the pathway functions depend on the metabolic reprogramming of cancer cells has not been well studied. In this study, we found that the expression level of Gli1, a key transcription factor downstream of the Hedgehog Signaling Pathway, is significantly increased in patients with pancreatic cancer resistant to gemcitabine neoadjuvant chemotherapy. Through metabolomics analysis, we confirmed that Gli1 can promote the transformation of cancer cells from a glycolytic-dominated metabolic pattern to a unique metabolic pattern called "Pentose Phosphate Recycling". Transcriptome sequencing and in vitro experiments suggest that Gli1 promotes pentose phosphate recycling through transcriptional activation of key enzymes Phosphogluconate dehydrogenase (PGD) and Transketolase (TKT). The identified metabolic rerouting in oxidative and non-oxidative pentose phosphate pathway has important physiological roles in maximizing NADPH reduction and nucleotide synthesis. Therefore, the pentose phosphate cycle driven by Gli1 can resist gemcitabine-induced DNA damage by promoting pyrimidine synthesis and resist gemcitabine-induced ferroptosis by scavenging lipid Reactive Oxygen Species (Lipid ROS). Combining the Gli1 inhibitor GANT21 with gemcitabine exerts a maximal tumor suppressor effect by simultaneously promoting DNA damage and ferroptosis. Collectively, these results reveal that Gli1 drives chemotherapy resistance in cancer cells by inducing metabolic reprogramming, providing a novel target and therapeutic strategy for reversing chemotherapy resistance.