Overexpression of p53 protein correlates with a high risk of malignant transformation of adenomas in patients with multiple colorectal adenomas

Squamous morula formation in colorectal adenoma: Immunohistochemical and molecular analyses

Little is known about the squamous morular component (SMC) in colorectal neoplasms because of its rarity. The aim of the present study is to elucidate the morphological, immunohistochemical and genetic characteristics of SMCs in colorectal adenomas. Five colorectal adenomas having SMCs were resected from five patients endoscopically. On immunohistochemical examination (four cases), all SMCs were positive for cytokeratin 5/6 in their cytoplasm and positive for β-catenin in their cytoplasm and nuclei. A nuclear positivity of p63 was detected in one SMC. All SMCs were negative for p53, chromogranin A, synaptophysin and NCAM. There was no Ki-67 expression in any of the SMCs. We detected none of mutations of β-catenin, KRAS and BRAF by microdissection and polymerase chain reaction-direct sequence in any of the four examined SMCs. SMCs are a rare but problematic finding in colorectal adenomas. Using immunohistochemistry for β-catenin, cytokeratin 5/6, Ki-67, p53, chromogranin A, synaptophysin and NCAM can facilitate the diagnosis of these peculiar cell nests.

Molecular and cellular biology of pre-malignancy in the gastrointestinal tract

Important pathogenic alterations within established cancers are acquired during the pre-malignant stage. These genetic alterations can be grouped into specific neoplastic pathways that differ within and between anatomical sites. By understanding the mechanisms that determine the initiation and progression of each pathway, it will be possible to develop novel approaches to the diagnosis, prevention and treatment of cancer. This chapter outlines the principles underlying the molecular characterization of pre-malignant lesions, taking colorectal neoplasia as the main model.

p53 immunohistochemical expression of Egyptian cervical carcinoma

Data concerning the expression of p53 in cervical carcinoma, one of the leading cause of death in developing countries, are still confusing. This study was designed to identify p53 in Egyptian cervical carcinoma in an attempt to evaluate its prognostic significance. Eleven chronic cervicitis and 38 invasive carcinoma (31 squamous cell carcinoma (sqcc) and 7 adenocarcinoma, ranging from stage IB to IVB), were stained with the monoclonal antibody anti p53, DO7, using the microwave for antigen retrieval. No immunoreactivity was detected in chronic cervicitis, while nuclear p53 reactivity was detected in all carcinoma and in squamous intra-epithelial lesions (SIL) overlying 8 sqcc. P53 immunohistochemical (IHC) expression was more pronounced in early clinical stages (p=0.007) and in adenocarcinoma compared to sqcc (p=0.015). A positive correlation was present between p53 and heat shock protein 70 (hsp70) expressions (p=0.005). No correlation could be found between p53 expression and tumor infiltrating lymphocytes, the presence or absence of either schistosomiasis or HPV infections. It can be concluded, that in the Egyptian population, p53 immunoreactivity appears to be an early event in cervical neoplasm, and seems to play an important role together with other cell regulatory proteins in the process of carcinogenesis, which could be different between sqcc and adenocarcinoma.

Histologic and immunohistochemical analysis of early submucosal invasive carcinoma of the colon and rectum

To investigate the development and progression of colorectal carcinoma, submucosal invasive carcinoma (SMC) with residual intramucosal neoplasm was studied histopathologically. Intramucosal neoplasm was confirmed by immunohistochemical staining against anti-alpha-smooth muscle actin antibody. Submucosal invasive carcinoma was classified into polypoid growth-type carcinoma (PGC) and non-polypoid growth-type carcinoma (NPGC), depending on the presence of intramucosal tumor proliferation. Tumors were > 15 mm in size in 78.2% of the PGC lesions studied, but the degree of submucosal invasion was minimal (invasion of the upper 500 microm of the submucosal layer) in 52.9% of the PGC lesions. Conversely, 64.4% of NPGC lesions were 15 mm in size and the degree of submucosal invasion was moderate or severe (involving the middle and deeper layer of the submucosa) for 72.9% of NPGC. In other words, lesions of NPGC were significantly smaller in size but showed deeper infiltration than PGC lesions. Furthermore, PGC was derived from intramucosal polypoid carcinoma (including carcinoma with adenoma) and was morphologically identical to polyp cancer as reported previously. However, NPGC was derived from the flat and/or depressed type of intramucosal carcinoma classified not as polyp type, but as the superficial type. Typical NPGC was, therefore, also of the superficial type. In addition, approximately 25% of PGC lesions were identified as having an adenoma-carcinoma sequence. There was no coexistence with adenoma in the NPGC lesions, suggesting de novo development. When the degree of histologic atypia in the two types of intramucosal carcinoma was compared, 74.7% of PGC lesions showed low-grade carcinoma, regardless of tumor size, while 62.7% of NPGC lesions showed high-grade carcinoma in the intramucosal lesion. Approximately 25% of carcinomas with low-grade atypia were positive for p53 (as were the high-grade lesions), but it was not expressed in the adenoma. Therefore, tumor development and the degree of invasion differed significantly between the two types of carcinoma.

Usefulness of proliferative activity, DNA ploidy pattern and p53 products as diagnostic adjuncts in colorectal adenomas and intramucosal carcinomas

Although numerous studies have assessed the biologic parameters of tumors, measurement of these parameters has had, to date, little impact on histologic diagnosis. Furthermore, analysis of a single parameter is insufficient to evaluate tumor malignant potential. In the present study, cell proliferation, DNA ploidy and p53 product were analyzed to objectify the tumor malignant potential in colorectal adenomas and intramucosal carcinomas. Sixty-one adenomas and 49 intramucosal carcinomas were studied using immunohistochemical analysis of Ki-67 and p53, silver-staining nucleolar organizer region (AgNOR) stain and DNA ploidy in fresh samples. Intramucosal carcinoma exhibited a greater Ki-67-positive rate and AgNOR count than the adenomas, although these parameters varied widely among samples. The incidence of aneuploidy and p53 over-expression in colorectal intramucosal carcinomas was significantly higher than in colorectal adenomas. These results indicate that DNA aneuploidy and p53 accumulation are the most reliable parameters for distinguishing benign and malignant lesions.