Schwartz B, Benharroch D, Prinsloo I, Cagnano E, Lamprecht S A
Clinical Biochemistry Unit; Ben-Gurion University of the Negev, Beer-Sheva, Israel.
Anticancer Res. 1995 Jan-Feb;15(1):211-8.
In the present study we used monoclonal antibodies to investigate the expression of phosphotyrosine, c-myc and c-Ha-ras proteins along the crypt continuum of normal and transformed rat colon tissue. Colon cancer was induced by administration of dimethylhydrazine. Particular attention was focused on the immunohistochemical pattern of murine colon mucosa during preneoplastic stages so as to permit the identification of putative changes in the expression/location of the oncoproteins prior to frank neoplasia. The immunohistochemical analysis of tyrosinephosphorylated proteins in the normal rat indicated that positive staining was mostly restricted to the lower colonic crypt zones. The carcinogenetic insult altered the magnitude and positional profile of phosphotyrosine along the colon crypt axis during the preneoplastic period. An intense positive reaction was observed in the upper crypt regions. Four weeks following the last DHM administration, viz. before tumor appearance, positive staining was evident in invasive adenocarcinoma tissue. In contrast to phosphotyrosine, the feeble c-myc immunohistochemical staining of normal rat colonic did not exhibit a focal topology. However, following DMH administration and prior to frank neoplasia, a substantial increase in the staining intensity for c-myc was noted, confined mostly to the supranuclear region of luminal cells. Invasive adenocarcinomas displayed intense cytoplasmic c-myc immunoreactivity. p21 c-Ha-ras expression and location along the colon crypt axis showed a different pattern when compared to p62 c-myc and phosphotyrosine. The p21 c-Ha-ras protein was prominently expressed in surface epithelium of normal and DMH-treated rats. Midcrypt colonocytes exhibited moderate p21 ras staining; in contrast, proliferating colonic cells resident in the lower crypt regions were consistently negative. These results suggest that c-Ha-ras gene product plays an important contributory role in determining the differentiated phenotype of the colonic cell.
在本研究中，我们使用单克隆抗体来研究正常和转化的大鼠结肠组织隐窝连续区域中磷酸酪氨酸、c-myc和c-Ha-ras蛋白的表达。通过给予二甲基肼诱导结肠癌。特别关注癌前阶段小鼠结肠黏膜的免疫组织化学模式，以便在明显的肿瘤形成之前识别癌蛋白表达/定位的假定变化。正常大鼠中酪氨酸磷酸化蛋白的免疫组织化学分析表明，阳性染色大多局限于结肠隐窝下部区域。致癌损伤在癌前阶段改变了磷酸酪氨酸沿结肠隐窝轴的强度和位置分布。在上部隐窝区域观察到强烈的阳性反应。在最后一次给予二甲基肼四周后，即在肿瘤出现之前，浸润性腺癌组织中可见明显的阳性染色。与磷酸酪氨酸不同，正常大鼠结肠的c-myc免疫组织化学染色较弱，未表现出局灶性拓扑结构。然而，在给予二甲基肼后且在明显的肿瘤形成之前，观察到c-myc染色强度显著增加，主要局限于腔面细胞的核上区域。浸润性腺癌显示出强烈的细胞质c-myc免疫反应性。与p62 c-myc和磷酸酪氨酸相比，p21 c-Ha-ras沿结肠隐窝轴的表达和定位呈现出不同的模式。p21 c-Ha-ras蛋白在正常和经二甲基肼处理的大鼠的表面上皮中显著表达。结肠隐窝中部的细胞呈现中度p21 ras染色；相反，位于隐窝下部区域的增殖结肠细胞始终为阴性。这些结果表明，c-Ha-ras基因产物在决定结肠细胞的分化表型中起重要的辅助作用。
