P53 and C-FOS overexpression in patients with thyroid cancer: an immunohistochemical study

A sequence of genetic events characterized by deletion and expression of several oncogenes may lead progressively to tumorgenesis. The expression of certain oncogenes is believed to be related with thyroid carcinogenesis and tumor progression. We investigated immunohistochemically p53 tumor suppressor gene and c-fos oncogene expression in forty patients with thyroid cancer. Thyroid biopsies from twenty patients with benign thyroid diseases were also examined. The forty patients with thyroid cancer varied histologically; 24 with papillary carcinoma (60%), 12 with follicular carcinoma (30%), 3 with anaplastic carcinoma (7.5%) and one with medullary carcinoma (2.5%). The patients with benign thyroid diseases consisted of 10 with adenomatous goiter (50%), 7 with goiter (35%) and three with Hashimoto thyroiditis (15%). Individual p53 and c-fos expression was more prevalent in thyroid carcinomas compared to benign tumors (p=0.001 and p=0.04, respectively). A marked increase of p53 and c-fos coexpression was found (p=0.02) in patients with thyroid cancer and metastasis to the regional lymph nodes. Furthermore c-fos was overexpressed in only female thyroid cancer patients. In conclusion, p53 and c-fos are significantly overexpressed in thyroid cancer patients, indicating their role in the genetic mechanisms leading to thyroid tumorigenesis. This hypothesis is further supported by the observation that p53/c-fos coexpression was related with more advanced disease status.

Immunohistochemical analysis of the expression of the c-myc oncoprotein in human stomach cancers

In an immunohistopathological study, we have used the specific monoclonal antibody myc 1-9E10 to the c-myc oncoprotein in 88 gastric carcinomas (22 gastric biopsies and 66 gastrectomies for cancer). Positive myc p62 immunoreactivity was shown in 48 (55%) cases with moderate or intense staining. The remaining 40 cases exhibited negative or equivocal staining. Normal stomach mucosa was generally nonreactive, with the exception of parietal cells. Elevated c-myc expression was not found to correlate with histological differentiation or in patients with metastases in one or more perigastric lymph nodes. A correlation was found between the level of c-myc expression and the stage of the disease, (p = 0.04); positive c-myc staining was found in 0/4 early gastric cancers and in 48/84 with advanced disease. Also, an association was found between the elevated c-myc expression and depth of invasion (p = 0.1; 0/4 mucosa and submucosa, 2/6 muscularis propria and 25/47 serosa). The c-myc monoclonal myc 1-9E10 may therefore be of use as a marker of advanced disease and depth of invasion in stomach cancer.

Evaluation of the ras and myc oncoproteins in benign gastric lesions

Ras and c-myc oncoprotein expression was analyzed using specific monoclonal antibodies Y13-259 (for ras p21) and mycl-9E10 (for c-myc p62) in 144 histological sections derived from benign gastric lesions. Increased expression of ras p21 was observed in inflammatory metaplastic, dysplastic, hyperplastic and cystic histological changes, and on the basis of ras p21 staining three distinct histological groups emerged: (i) cystic changes, hyperplastic polyps; (ii) inflammatory gastritis; (iii) metaplastic, dysplastic and adenomatous polyps. Elevated levels of ras p21 expression were found at significantly higher levels than those of c-myc expression in dysplastic lesions. However the expression of the c-myc oncoprotein was less frequent than ras p21 in all other histological types. With the exception of parietal cells, normal stomach mucosa was found to express low levels of both ras p21 and c-myc oncoproteins.

Expression of the ras oncoprotein in gastric carcinomas and adjacent mucosa

We have employed an immunohistochemical analysis to study the ras p21 oncoprotein in a total of 88 gastric carcinomas, which were associated (in 24 cases) with intestinal metaplasia. Our results suggest an association of the expression of ras p21 with metaplastic and neoplastic gastric mucosa. The comparative study showed that 58 of the 88 gastric carcinoma cases studied exhibited negative or equivocal staining (-/+). The remaining 30 were positive with moderate (+) or intense (++) staining. There was an agreement in that histologic type and tumor grade had a strict correlation with staining intensity. Intestinal metaplasia had a higher percentage of positively stained cells (+ or ++). Moreover, there was a selective positive staining in the parietal cells of the gastric fundus in sections from adjacent non-neoplastic mucosa.