CASTOR1 phosphorylation predicts poor survival in male patients with KRAS-mutated lung adenocarcinoma.

Background: Lung cancer, a leading global cause of cancer-related mortality, necessitates enhanced prognostic markers for improved treatment outcomes. We have previously shown a tumor suppressive role of cytosolic arginine sensor for mTORC1 subunit 1 (CASTOR1), which is targeted for degradation upon phosphorylation at S14 (pCASTOR1) in multiple types of cancer. This study focuses on the predictive value of pCASTOR1 in lung adenocarcinoma (LUAD) patients with KRAS mutations.

Results: Employing a newly developed pCASTOR1 specific antibody, we found that tumor cells exhibited significantly elevated pCASTOR1 scores compared to non-tumor cells (P < 0.05). Higher pCASTOR1 scores predicted poorer overall survival (OS) (HR = 3.3, P = 0.0008) and relapse-free survival (RFS) (HR = 3.0, P = 0.0035) in male patients with KRAS mutations. pCASTOR1 remained an independent predictor for OS (HR = 4.1, P = 0.0047) and RFS (HR = 3.5, P = 0.0342) after controlling for other factors. Notably, in early-stage LUAD, elevated pCASTOR1 scores were associated with significantly worse OS (HR = 3.3, P = 0.0176) and RFS (HR = 3.1, P = 0.0277) in male patients with KRAS mutations, akin to late-stage patients.

Conclusion: Elevated pCASTOR1 scores serve as biomarkers predicting poorer OS and RFS in male LUAD patients with KRAS mutations, offering potential clinical utility in optimizing treatment strategies for this subgroup.