Background: P53 tumor-suppressor GENE which encodes a nuclear phosphoprotein that arrests cell cycle progress at G1, is one of the most frequently mutated GENEs in human cancers.Materials and Methods: In this study, 40 cases of Hodgkins disease (HD) which is the most common lymphoma in young adults, have been investigated for P53 GENE mutations. For each case, sections of paraffin-embedded tissue blocks were cut, a light hematoxylene stain was applied, and in order to enrich our samples for a higher percentage of Reed-Sternberg (RS) cells which are thought to be the neoplastic component of HD lesions, a microdissection technique was used. We used polymerase chain reaction (PCR) amplitication technique and single strand conformational polymorphism analysis (SSCP) to study mutations within exons 5 to 8 of GENE P53.Results: Six shifts were detected in five cases (12.5%), identified by SSCP (one shift in exon 5A, one in exon 5B, one in exon 6, two in exon 7 and one in exon 8). Conclusion: Since the specificity of PCR-SSCP is more than 95% for 100 to 300 bp polymerase chain reaction fragments, it is conceivable that P53 GENE mutation is not a common feature in HD. However, the samples with abnormal SSCP require nucleotide sequencing studies to assess whether the abnormal migration represents a mutation or a polymorphism.

Background: The involvement of apoptotic GENEs in tumor GENEsis is well recognized. It was reported that P53 to be expressed more frequent in invasive thymoma than thymoma and expression of bcl-2 is positively correlate with aggressiveness of thymic epithelial neoplasm. We aimed to assess the expression of P53, bcl-2, and Rb GENEs related protein in thymoma and invasive thymoma. Materials & Methods: We analyzed formalin-fixed paraffin embedded tissue sections of thymic epithelial tumor during 1999 to 2001 for P53, bcl-2, and Rb protein by Immunohistochemistry. Results: Fifteen cases of thymic epithelial tumor including nine thymoma and six invasive thymoma were collected. P53 nuclear staining were found in epithelial cells of 14 cases (8 thymoma and 6 invasive thymoma). Rb protein was present in 10 cases (5 thymoma and 5 invasive thymoma). Cytoplasmic staining for bcl-2 was positive in six cases, of these, two were invasive. Conclusion: Between Products of these three GENEs, P53 protein accumulation is more pronounced than other two, and there is inverse relationship between P53 and bcl-2 expression. The accumulation of P53, bcl-2, and Rb does not correlate with invasiveness of tumor. We may suggest that difference in expression of P53, in our study, may occur in the absence of mutation due to some ethnic or environmental factors which needs more investigation. We also suggest that organotypical differentiation present at the molecular level in Thymoma.