Evaluation of Glypican-3 Expression in Poorly Differentiated Carcinomas of Lung Origin

Abstract

Glypican-3 (GPC-3) is a glycoconjugate protein of heparan sulfate proteoglycan family and is important for embryogenesis but silenced in adult healthy tissue. GPC-3 protein is abnormally expressed in hepatocellular carcinoma (HCC) and has been used as a marker for pathological diagnosis of primary and metastatic HCC. However, GPC-3 expression has also been found in some tumors other than HCC. This study is to investigate the expression of GPC-3 expression immunohistochemically and the staining pattern in poorly differentiated carcinomas of lung primary in order to assess the value of GPC-3 as a marker for diagnosing metastatic HCC in lung. Lung tissue from 44 patients diagnosed with poorly differentiated carcinoma were evaluated, including 23 lung adenocarcinomas, 19 squamous cell carcinomas and 2 adenosquamous carcinomas. Immunohistochemical stains of GPC-3 was performed on tumor tissue samples. The expression pattern of GPC-3 was analyzed. Expression of GPC-3 was found in 45% of primary lung cancers, including 79% of squamous cell carcinomas, 18 % of adenocarcinomas, and 50% of adenosquamous carcinomas. The poorly differentiated carcinomas showed predominantly patchy positivity. The staining pattern ranged from weak granular cytoplasmic positivity to a strong membranous and cytoplasmic positivity, and both cytoplasmic and nuclear positivity. GPC-3 expression was not seen in non-neoplastic lung tissue. GPC-3 is a relatively specific marker for HCC. In this study, we demonstrated the expression of GPC-3 in a significant number of poorly differentiated carcinoma of lung. Therefore, in context of a possible metastatic HCC to the lung, caution should be made by using GPC-3 as a differential marker for HCC, and a panel of stains should be considered.

[N A J Med Sci. 2020;1(1):018-023.   DOI:  10.7156/najms.2020.1301018]

Key Words: glypican-3, lung carcinomas, immunohistochemistry, hepatocellular carcinoma