Significance of p53 protein expression and p53 gene mutation in so-called pulmonary sclerosing hemangioma

Abstract

So-called pulmonary sclerosing hemangioma (PSH) is an uncommon tumor of the lung and its histogenesis and origin are uncertain to date. A general consensus appears to have been reached that PSH is a benign neoplasm, but a few PSHs are found to invade and metastasize. The expression of p53 protein and mutation of p53 gene are significant parameters which can reflect biological behavior of tumor cells. The aim of this study is to investigate the p53 protein expression and p53 gene mutation in PSH, and explore their significance. The expression of p53 protein and mutation of p53 gene were examined in polygonal cells and cuboidal cells of PSH by immunohistochemical method, laser capture microdissection (LCM), single-stranded conformation polymorphism (SSCP) and DNA sequencing. The positive rate of p53 protein was 21.1% (4/19) and the mutation rate of p53 gene was 26.3% (5/19) by SSCP and 42.1% (8/19) by DNA sequencing respectively. In 4 cases of immunopositive PSH tissues, 2 were missense mutations, and 1 was both missense and frameshift mutation. Out of 15 cases of immunonegative PSH tissues, 4 were frameshift mutations and 1 was missense mutation. Of 8 PSH tissues with p53 gene mutation, 5 were identified in only polygonal cells, and 2 in only cuboidal cells and 1 in both polygonal and cuboidal cells. The expression of p53 protein may not be indicative of p53 gene mutation in PSH. The alteration of p53 gene and the expression of p53 protein are identified in both polygonal and cuboidal cells. The high mutation rate of p53 gene may indicate that PSH has potentially malignant biological behavior.