Expression of the tyrosine kinase activity growth factor receptors (EGFR, ERB B2, ERB B3) in colorectal adenocarcinomas and adenomas.

The overexpression of three growth factor receptors: epidermal growth factor receptor (EGFR), ERB B2 and ERB B3 was evaluated immunohistochemically in 77 malignant and 15 benign colorectal neoplasms considering clinicopathological variables (histological structure, grade of differentiation, tumor localization, clinical stage of the disease). The relationship between the coexpression of EGFR-related proteins in individual patients was also evaluated. EGFR expression was revealed in comparable percentages of colorectal adenoma and in adenocarcinoma cases (80% and 70%) while ERB B2 expression was detectable more frequently in adenoma than in adenocarcinoma cases (87% and 54%). The presence of ERB B3 was observed in a higher percentage of adenocarcinoma than adenoma cases (65% and 40%). There was no correlation between the expression of studied tyrosine kinase receptors and histological grade or Dukes' clinical stage and localization (proximal or distal) of colorectal adenocarcinoma. The incidence of EGFR and ERB B2 expression was higher in tubulovillous (100% for both receptors) than in tubular adenomas (63% and 75%), while the ERB B3 receptor was revealed more frequently in tubular than in tubulovillous neoplasms (50% and 28%). These differences appeared to be statistically nonsignificant. The concomitant expression of two growth factor receptors was observed in a higher percentage of colorectal adenomas than adenocarcinomas, and the coexistence of three growth factors was revealed in comparable percentages in malignant and benign colorectal tumors. Our results support the promotional rather than direct transformational role for the EGFR supergene family in colorectal tumorigenesis. The frequently observed coexpression of more than one EGFR-related protein in colorectal neoplasms indicates the possible cooperation of these receptors in mitogenic signaling transduction, facilitating the development and maintenance of the malignant phenotype.

Expression of epidermal growth factor receptor family proteins (EGFR, c-erbB-2 and c-erbB-3) in gastric cancer and chronic gastritis.

The expression and coexpression of EGFR, c-erbB-2 and c-erbB-3 in 21 gastric cancers and 20 chronic gastritis was examined using immunohistochemistry on fresh frozen tissues considering clinicopathological variables. Generally, gastric cancer patients showed a higher incidence of EGFR, c-erbB-2 and d-erbB-3 overexpression than the group with chronic gastritis (81% and 43%; 38% and 45%; 35% and 20%, respectively), however, statistically significant differences were found only for EGFR expression (p = 0.01). No association between immunoreactivity of all growth factor receptors and the histopathological structure of gastric cancer was observed. EGFR and c-erbB-3 proteins were detected more frequently in patients with III/IV than in I/II of TNM stages, while c-erbB-2 overexpression was higher in I/II vs. III/IV stages. In chronic gastritis with intestinal metaplasia and or coexisting carcinoma lesions, a higher frequency of the expression of studied proteins was observed in comparison with chronic gastritis without those alternations; however, these differences were statistically insignificant. The percentage of positive cases with coexpression of two proteins was comparable in gastric cancer and chronic gastritis (33% and 35%) but the simultaneous expression of all three receptors was evident only in gastric cancer (19%). Our results indicate that at least one or two members of EGFR related receptors could appear in the early stages of gastric tumorigenesis. The enhancement of c-erbB-2 and c-erbB-3 reactivity seems to cooperate with EGFR activation in the gastric cancer development. Our results indicate the promotional rather than direct transformational role for EGFR supergene family in gastric carcinogenesis.