Expression Profile of Metabotropic Glutamate Receptors in Lung Adenocarcinoma: GRM5 and Validation of Its Targeting Drug Cinchonine

The incidence and mortality rates of lung adenocarcinoma (LUAD) continue to rise, highlighting an urgent need for novel therapeutic targets. In this study, bioinformatics analysis revealed that members of the metabotropic glutamate receptor (mGluR) family are significantly correlated with the expression profile, prognosis, genetic mutations, and tumor immune microenvironment of LUAD, with GRM5 being the most significantly associated member. Overexpression of GRM5 has been shown to inhibit LUAD proliferation and induce apoptosis, while cinchonine (CN) treatment further enhances these effects, suggesting that CN may act as a GRM5 agonist to synergistically exert antitumor activity. Transcriptome sequencing further identified four key downstream targets and their associated signaling pathways. In summary, this study confirms that GRM5 can serve as a potential prognostic biomarker and therapeutic target for LUAD, while the small-molecule compound CN shows promise as an antitumor candidate drug targeting GRM5.