Comparison of Galectin-7 Serum Concentrations in Squamous Cell and Adenocarcinoma Lung Cancers

Abstract

Lung cancer is the leading cause of cancer-related death in both men and women in the United States. Non-small cell lung cancer is the most prevalent and includes adenocarcinoma (AD), and squamous cell lung cancers. The unique cellular biology of these cancers could potentially allow for serological detection and identification via tissue specific protein markers. Galectins are a group of β-galactoside binding proteins which are known to be alternatively expressed in cancers and are being studied for their biomarker potential. Galectin-7 is expressed in epithelial tissues as well as in all layers of the epidermis as it is normally highly expressed by squamous cells. We evaluated the potential for galectins to be used as a serum biomarkers and delineators of two non- small cell lung cancer subtypes. The serum concentrations of galectin-7 were measured in 85 lung cancer patients using ELISA. Forty-eight samples were from adenocarcinoma patients and 37 were from squamous cell carcinomas patients. The serum galectin-7 concentrations in cancer patients were compared to healthy controls and by their histological subtypes. Oneway analysis was performed using Tukey-Kramer HSD for pairwise comparisons. Galectin-7 concentrations were significantly elevated in serum samples from squamous cell lung cancer patients (mean, 2.45 ng/mL) relative to healthy controls (N, 26; mean, 1.16 ng/mL; p- value, 0.0010) and relative to adenocarcinoma lung cancer patients (mean, 1.47 ng/mL; p-value, 0.0040). These results show that serum galectin-7 is increased in patients with squamous cell lung cancer compared to adenocarcinoma lung cancer. Further benchwork would include (1) measuring serum concentrations of galectin-7 by stage of squamous cell lung cancer, (2) identifying concentrations of serum galectin-7 in other lung cancer subtypes, and (3) in other non-pulmonary squamous cell carcinomas such as skin, cervical, and head and neck. Potential clinical applications of this work would include the measurement of galectin-7 in blood samples of cancer patients to aid in cancer screening and tumor type identification.