Background The fluorescence probe method developed in recent years allows rapid and highly specific detection of cancer cells by using probes that emit fluorescence only in malignant tissues. This method is easy to perform and provides clear visualization, showing promise for both basic research and clinical applications. Previous studies have reported its applicability to various cancer cells such as breast cancer, esophageal cancer, lung adenocarcinoma, prostate and thyroid cancer.　However, the cancer specificity of GGT1 has not yet been fully clarified. This study aimed to elucidate the molecular mechanisms underlying GGT1 expression and its potential cancer specificity, focusing on AKT pathways.

Fluorescence probe assays were reproduced in cultured cell lines, and immunohistochemical analyses were performed on GGT1-positive cells. In addition, three specific inhibitors were employed: GGsTop (a selective GGT inhibitor), Lonafarnib (a RAS farnesylation inhibitor), and SC66 (an AKT inhibitor that blocks PIP3 binding and suppresses AKT activation).

Immunohistochemical analysis demonstrated positive staining for AKT related protein in GGT1-positive cells, indicating reproducible involvement of AKT in GGT1 activation. Ki-67, p53, and Cyclin D1 positivity confirmed enhanced cell proliferation and cell cycle activation. Newly observed expression of ERK1/2 and phospho-ERK1/2 suggested the participation of transcriptional regulatory pathways. Inhibition experiments showed that phospho-AKT was suppressed while AKT remained positive, implying that AKT phosphorylation may depend on PDPK1 activity.

Immunohistochemical findings in A549 and HeLa cell lines were consistent with previous reports, confirming the reproducibility of GGT1 activation pathways. The results suggest that GGT1 expression involves AKT-, and ERK-mediated signaling, with a possible role for mTOR in the AKT pathway. These findings provide molecular evidence supporting the cancer-specific mechanism of GGT1 and strengthen the clinical significance of fluorescence probe–based cancer detection as a rapid and reliable diagnostic approach.