The Biological Role of Genes Overexpressed in Colorectal Cancer

• Main Authors: Jau Min Wong, 翁昭旼
• Other Authors: Chang Yi Wang; Lan Bo Chen
• Format: Others
• Language: zh-TW
• Published: 1994
• Online Access: http://ndltd.ncl.edu.tw/handle/05682437007153105652

博士 === 國立臺灣大學 === 臨床醫學研究所 === 82 === We had taken the strategy of differential screening of cDNA library between two human colorectal cancer cell lines with different differentiation status, to search for possible useful cancer markers. we has cloned a few cDNA clones which are overexpressed in colorectal cancer tissues. One of these clones was found to be the 67 kDa human laminin receptor. Another clone had been found to be the ubiquitin ribosomal protein 27a gene. We had screened a .lambda.gt10 cDNA library made from the CX-1 human colon cancer cell line. A clone named J9 was picked and was judged as a full length c DNA clone, it encodes a 295 amino acid protein with calculated molecular weight of about 33 kDa. Besides the unexpected small molecular weight of the coding protein, J9 clone lacks a leader signal sequence at its encoding protein''s N terminal, also it lacks a definite transmembrane domain judged by hydropathy plot of its protein sequence. We took the advantage of the full length character of this J9 clone, tried to do in vitro expression of this gene to solve above mentioned puzzles. Protein SDS-PAGE of the translation product revealed molecular weight of about 45 kDa. The biological meaning of the phenomenon of overexpression of these two genes was tested with the model of stimulation of quescient normal rat fibroblast cell line. The ubiquitin-S27a ribosomal protein gene was shown to be a typical early growth response gene, which is activated at early stage even in the absence of protein synthesis. The 32/67 kDa laminin receptor gene was found to be activated in early stage of growth stimulation but the nuclear run on test failed to prove that there is an early 32/67 kDa laminin receptor gene specific mRNA transcription activity.