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Objective To detect DNA and chromosomes instabilities during the progression of tumors and screen new molecular markers coupled to putative or unknown oncogenes and/or tu mor suppressor genes. Methods Five kinds of tumors, in a total of 128 specimens, were analyzed by random ampl ified polymorphic DNA (RAPD) PCR. Bands representing instabilities were recove red, purified, and cloned, labeled as probes for Southern and Northern blot ana lysis and DNA sequencing. Results Sample 5 and 3 of the gastric cancer tissues showed the highest genomic changes and the average detectability in five cancers was up to at least 40% (42 .2%-49.4%). There were significant differences in the ability of each primer to detect genomic instability ,which ranged from 27% (primer 8) to 68% (primer 2 ). Band B is a single copy fragment ,and was found to be an allelic loss in ga stric and colon cancers. It is a novel sequence and was registered in GenBank with Accession Number AF151005. Further analysis revealed that it might be p art of a cis- regulatory element of a new tumor suppressor gene, containing a promoter of cis-action “CACA” box, an enhancer of “GATA” family and a start c odon. Conclusions It was impossible or difficult to get great achievements for cancer treatm ents with the procedure of gene therapy only to one oncogene or one tumor suppre ssor gene because the extensive DNA variations occurred during the progression o f tumor. RAPD assay connected with other techniques was a good tool for the detection of genomic instabilities and direct screening of some new molecular m arkers related to tumor suppressor genes or oncogenes.
Objective To detect DNA and chromosomes instabilities during the progression of tumors and screen new molecular markers coupled to putative or unknown oncogenes and/ or tu mor suppressor genes. Methods five kinds of tumors, in a total of 128 specimens, were analyzed by random ampl ified Polymorphic DNA (RAPD) PCR. Bands representation instabilities were recove red, purified, and cloned, labeled as probes for Southern and Northern blot analysis and DNA sequencing. Results Sample 5 and 3 of the gastric cancer structure showed the highest genomic changes and the Average detectability in five cancers was up to at least 40% (42.2%-49.4%). There were significant differences in the ability of each primer to detect genomic instability ,which ranged from 27% (primer 8) to 68% ( Primer 2 ). Band B is a single copy fragment ,and was found to be an allelic loss in ga stric and colon cancers. It is a novel sequence and was registered in GenBank with Accession Number AF151005. Further analysis Ed that it might be p art of a cis- regulatory element of a new tumor suppressor gene, containing a promoter of cis-action “CACA” box, an enhancer of “GATA” family and a start c odon. It was impossible or difficult to get great achievements for cancer treatm ents with the procedure of gene therapy only to one oncogene or one tumor suppre ssor gene because the extensive DNA defects occurred during the progression of tumor. RAPD assay connected with other techniques was a good Tool for the detection of genomic instabilities and direct screening of some new molecular m arkers related to tumor suppressor genes or oncogenes.