Immunohistochemical expression of basement membrane laminin in histological grades of oral squamous cell carcinoma: A semiquantitative analysis

BACKGROUND AND OBJECTIVES: To determine the immunohistochemical (IHC) localization of basement membrane component laminin in histological grades of oral squamous cell carcinoma (OSCC). The purpose of this study was to demonstrate the loss of continuity of the basement membrane in OSCC using an antibody directed against laminin using advanced polymer staining system. MATERIALS AND METHODS: A total of 30 cases of OSCC: 10 cases of well differentiated squamous cell carcinom (WDSCC), 10 cases of moderately differentiated squamous cell carcinoma (MDSCC), and 10 cases of poorly differentiated squamous cell carcinoma (PDSCC) were subjected to heat-induced antigen retrieval method using ethylene-di-amine-tetraacetic acid buffer in a microwave oven. Then the sections were stained with anti-laminin polyclonal antibody and visualized using super sensitive polymer horseradish peroxidase detection system. In each case, the integrity of the basement membrane laminin was assessed by using statistical analysis. RESULTS: Statistical analysis showed a decreased distribution of laminin from WDSCC to MDSCC to PDSCC (P value 0.0573). The intracytoplasmic staining of laminin gradually increased from WDSCC to MDSCC to PDSCC (P value 0.0198). INTERPRETATION AND CONCLUSION: WDSCC cases showed more laminin expression in basement membrane around the tumor islands and less loss of continuity compared to MDSCC and PDSCC cases suggesting a greater enzymatic degradation of basement membrane components in MDSCC and PDSCC than WDSCC. The loss of structural basement membrane laminin and the presence of laminin in the tumor cells of PDSCC cases suggest that laminin helps in tumor invasion. The expression of laminin in the basement membrane may be a useful parameter to evaluate tumor histologic differentiation and aggressiveness.