Abstract C175: The potential effect of KRAS inhibitors on tumor microenvironments

Abstract

Abstract KRAS is one of the most common driver oncogenes among various cancer types. Researches aiming to develop KRAS inhibitors has been surging recently and the first clinical KRAS inhibitor sotorasib was approved for non-small cell lung cancer in the US and Japan. As KRAS activity has been reported to have certain effects on tumor microenvironments, KRAS inhibitor could potentially induce collateral outcomes on tumor microenvironment. Therefore, I have analyzed the potential influences of resistance to KRAS inhibitors on the tumor microenvironment. At first, I have established pancreatic cancer cell line MIA-Paca2 that acquired resistance to sotorasib, MIA/AMG-R, by continuously exposing them to sotorasib (1 µmol/L). An RNA sequencing analysis were performed with MIA/AMG-R and revealed that a gene set related to hypoxia were upregulated. When non-small cell lung cancer cell line NCI-H358 cells were exposed to sotorasib (1 µmol/L) for 4 hrs, the protein levels of HIF-1A decreased while that in MIA Paca-2 cells were unaffected. To evaluate at which steps of protein synthesis from gene transcription to through protein degradation of HIF-1A, NCI-H358 cells were treated with transcription inhibitor actinomycin D, translation inhibitor cycloheximide or proteasome inhibitor MG-132. The treatment of transcription inhibitor actinomycin D on NCI-H358 cells for 6 hrs did not lead to the decrease of HIF-1A protein level however, translation inhibitor cycloheximide induced drastic decrease in HIF-1A protein. Although exposure of NCI-H358 cells to MG-132 increased the expression level of HIF-1A, the combinational treatment of sotorasib and MG-132 still led to slight decrease in HIF-1A protein level. Also, MG-132 failed to recover the protein expression level decreased by cycloheximide treatment. In total, the cellular expression level of HIF-1A is possibly dependent on translation activity and KRAS inhibitor potentially affect the HIF-1A expression through the regulation of its translation. Conclusively, KRAS inhibitors could potentially be used to reprogram the hypoxic tumor microenvironments besides its primary effect against the downstream signaling of KRAS. Citation Format: Noritaka Tanaka, Takeharu Sakamoto. The potential effect of KRAS inhibitors on tumor microenvironments [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2023 Oct 11-15; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2023;22(12 Suppl):Abstract nr C175.