Experimental validation of the complement protein C3a down expression in the plasma of patients with squamous cell carcinoma of the penis

Abstract

Objectives: We have previously shown the importance of the complement system in differentiating between patients with squamous cell carcinoma of the penis (SCCP) and controls. These patients had low expression of C3a and C4 fragments. Therefore, in this study, we investigated the complement protein C3a as a potential circulating biomarker in these patients by a commercially available enzyme-linked immunosorbent assay (ELISA) test.

Patients and methods: Plasma samples from 39 patients with SCCP, 15 patients with prostate cancer, and 50 healthy male subjects were evaluated using the ELISA-Bioscience OptEIA Kit human anti-C3a (BD). The nonparametric Mann-Whitney test was used for comparison of means among the groups.

Results: The complement protein C3a was found down expressed in patients with SCCP (P<0.05) in comparison to either subjects with good health or subjects with prostate cancer.

Conclusion: Experimental validation of the down expression of C3a was well succeeded using a commercial ELISA kit. Complement system fragment C3a is down expressed in patients with SCCP. Besides, C3a is also low expressed in the plasma of patients with initial prostate cancer when compared to healthy subjects. These results suggest that the innate immune response might be suppressed in patients with these malignancies.

Keywords: Circulating biomarker; Enzyme-linked immunosorbent assay (ELISA); Human complement C3a-desArg/C4a-desArg; Penile cancer; Plasma; Tumor microenvironment.