Carbamoyl phosphate synthetase 1 (CPS1) drives ammonia conversion to carbamoyl phosphate, and its overexpression supports pyrimidine synthesis and tumor growth, highlighting the potential of CPS1 inhi Show more
Carbamoyl phosphate synthetase 1 (CPS1) drives ammonia conversion to carbamoyl phosphate, and its overexpression supports pyrimidine synthesis and tumor growth, highlighting the potential of CPS1 inhibition as a therapeutic target. In this issue of Cell Chemical Biology, Yao et al. (2020) introduce H3B-120 as a promising novel inhibitor of CPS1. Show less
Liver kinase B1 ( LKB1 ) is a tumor suppressor in lung adenocarcinoma (LADC). We investigated the proteomic profiles of 45 LADC cell lines with and without LKB1 inactivation. Carbamoyl phosphate synth Show more
Liver kinase B1 ( LKB1 ) is a tumor suppressor in lung adenocarcinoma (LADC). We investigated the proteomic profiles of 45 LADC cell lines with and without LKB1 inactivation. Carbamoyl phosphate synthetase 1 (CPS1), the first rate-limiting mitochondrial enzyme in the urea cycle, was distinctively overexpressed in LKB1-inactivated LADC cell lines. We therefore assessed the role of CPS1 and its clinical relevance in LKB1-inactivated LADC. Mass spectrometric profiling of proteome and metabolome and function of CPS1 were analyzed in LADC cell lines. CPS1 and LKB1 expression in tumors from 305 LADC and 160 lung squamous cell carcinoma patients was evaluated by immunohistochemistry. Kaplan-Meier and Cox regression analyses were applied to assess the association between overall survival and CPS1 and LKB1 expression. All statistical tests were two-sided. CPS1 knockdown reduced cell growth, decreased metabolite levels associated with nucleic acid biosynthesis pathway, and contributed an additive effect when combined with gemcitabine, pemetrexed, or CHK1 inhibitor AZD7762. Tissue microarray analysis revealed that CPS1 was expressed in 65.7% of LKB1-negative LADC, and only 5.0% of LKB1-positive LADC. CPS1 expression showed statistically significant association with poor overall survival in LADC (hazard ratio = 3.03, 95% confidence interval = 1.74 to 5.25, P < .001). Our findings suggest functional relevance of CPS1 in LKB1-inactivated LADC and association with worse outcome of LADC. CPS1 is a promising therapeutic target in combination with other chemotherapy agents, as well as a prognostic biomarker, enabling a personalized approach to treatment of LADC. Show less