The Stress-Inducible Heat Shock Protein 70 (HSPA1A) as A Novel Biomarker in Lung Tumors: A Promoting Study

Abstract

     Heat shock proteins (HSPs) are a group of intracellular proteins that promote proteins folding and unfolding under normal and/or stress conditions. In addition to their intracellular location, HSPs are found on the plasma membranes of stressed, but not normal, cells and in the extracellular milieu where they can trigger an immune response. For instance, the inducible form of heat shock protein 70 (HSPA1A) was found to be overexpressed, intra or extracellularly, by many types of stressed cells. In our study, we aim to investigate the levels of HSPA1A in the serum of untreated lung tumor patients and its expression in the tissues derived from lung tumors and chronic obstructive pulmonary diseases (COPD) and healthy tissues. Analyses of serum and tissue samples were performed by utilizing ELISA assay and immunohistochemical staining, respectively. The results showed significant differences in the mean levels of serum HSPA1A of the patients (1.66± 0.165) as compared to healthy control (0.938±0.330). Significant differences were also found between these levels in the serum of smoker and nonsmoker patients (2.006±0.342 and 1.353± 0.067, respectively). The protein levels in the patient's serum were also found to be 29.5% correlated to smoking history. No significant differences were found in terms of gender and age within the two groups of patients and healthy volunteers. Our results showed HSPA1A protein levels to be correlated to gender (13.5%) and age in patients and healthy volunteers (14.8% and 0.4%, respectively). In the tissues of the clinicopathological groups, HSPA1A was found to be overexpressed in benign (IRS= 8.5) and malignant tumors (IRS= 8.9) in comparison with both COPD (IRS= 4.4) and healthy tissues (IRS= 0.00). Our pilot results could support the suggestion of HSPA1A as a novel biomarker in lung tumors, as proposed by previous studies.