Targeting type Iγ phosphatidylinositol phosphate kinase overcomes oxaliplatin resistance in colorectal cancer
Minhao Yu, Hao Wang, Wei Zhao, Xiaoxiao Ge, Wei Huang, Fengjuan Lin, Wenbo Tang, Ang Li, Sailiang Liu, Rongkun Li, Shu‐Heng Jiang, Junli Xue
Abstract
Oxaliplatin is a widely used chemotherapy drug for advanced colorectal cancer (CRC) and its resistance is a major challenge for disease treatment. However, the molecular mechanism underlying oxaliplatin resistance remains largely elusive. Methods: An integrative analysis was performed to determine differentially expressed genes involved in oxaliplatin resistance. Loss-and gain-of-function studies were employed to investigate the roles of type I phosphatidylinositol phosphate kinase (PIPKI) on oxaliplatin resistance in CRC cells. Exosomes derived from CRC cell lines were assessed for PD-L1 level and the ability to promote oxaliplatin resistance. Quantitative real-time PCR, immunofluorescence, luciferase reporter assay, Western blotting and other techniques were conducted to decipher the molecular mechanism. Results: PIPKI was identified as a critical gene related to oxaliplatin resistance in CRC. Genetic manipulation studies revealed that PIPKI profoundly facilitated oxaliplatin resistance and affected the expression of DNA damage repair proteins. Mechanistically, PIPKI promoted the expression of the immune checkpoint molecule PD-L1 via activation of NF-B signaling pathway. Genetic silencing of PD-L1 did not affect CRC cell proliferation but significantly sensitized CRC cells to oxaliplatin. Notably, PD-L1 was revealed to be encapsulated in the exosomes, and the addition of exosomal PD-L1 to sh-PD-L1 CRC cells restored oxaliplatin resistance. Pharmacological hijacking PIPKI-exosomal PD-L1 axis largely reduced oxaliplatin resistance in CRC cells. In vivo experiments showed that PD-L1 loss significantly blocked oxaliplatin resistance and the addition of PD-L1-enriched exosomes promoted tumor growth and reduced mouse survival time. Conclusion: Our findings reveal a previous unprecedented role of PIPKI in oxaliplatin resistance and provide a key mechanism of exosomal PD-L1 in CRC with potential therapeutics.