Potential role and prognostic value of Globo-H in lung cancer.

Abstract

e20037 Background: Globo-H (GH), a globo-series carbohydrate antigen highly expressed on multiple epithelial cancers, is a promising target for cancer immunotherapy. Clinical trials have been conducted to evaluate the efficacy of anti-GH vaccine Adagloxad Simolenin/OBI-821 (in Ph 3) and OBI-833/OBI-821 (in Ph 2) in cancer patients. Epidermal growth factor receptor (EGFR) mutations are well known as a frequent class of driver mutations in lung cancer (LC), which are responsible for tyrosine kinase inhibitors. Besides high expression in cancer cells, GH has been implicated in regulation of EGFR signaling pathway. Knockdown of key enzyme involved in GH biosynthesis β1,3-galactosyltransferase V (β3GalT5) induces apoptosis through disruption of EGFR-related signaling protein complex. In addition, GH is reported to associate the EGFR mutant in LC patients. This study aims to further investigate the potential role of GH in LC. Methods: Clinical study: The level of GH expression was evaluated by immunohistochemistry (IHC) using H-score in clinical samples from 141 patients with lung adenocarcinoma. In vitro study: FACS and Western blotting methods were used to measure the levels of total EGFR, phospho-EGFRs or GH in LC cell lines. Microwestern protein array (MWA) analysis was performed in LC NCI-H1975 cells. Results: Clinical study: Positive GH expression (H score≥1; 18.4%) was significantly associated with poor differentiation grade (p = 0.044) in all samples and disease specific survival in patients with metastasis and stage 4 LC (p = 0.033). In vitro study: Inhibition of EGFR by an EGFR-specific shRNA resulted in a decrease of GH expression in LC cells while overexpression of EGFR resulted in an increase of GH levels. β3GalT5 knockout cells and anti-GH-antibody-treated cells showed a reduction of cell proliferation as well as the total level of EGFR and phosphor-EGFRs expression, which is consistent with the results from previous studies. MWA analysis on LC cells with β3GalT5 knockout, GH ceramide-treated β3GalT5 knockout cells and anti-GH Ab-treated LC cells indicated a positive correlation between the level of GH and EGFR-related signaling proteins including phosphor-JNK, phosphor-c-Jun, phosphor-PP2A, phosphor-PP2A, phosphor-AKT, and Cyclin D1 proteins. In addition, JNK signaling inhibitor partially reduced GH expression in NCI-H1975 cells. These results revealed the mechanistic link between GH regulation and tumor promoting signals in LC. Conclusions: GH expression was associated with the worse survival of LC patients in clinical setting. In addition, the level of GH is positively correlated with levels of EGFR and EGFR-related signaling proteins in vitro. Expression of GH can induce the expression of EGFR and vice versa in LC cells. Furthermore, EGFR downstream JNK signaling pathway might involve in GH regulation by EGFR. Taken together, GH-targeting therapy has a potential application for the treatment of LC patients.