Genomic instability in silica- and cadmium chloride-transformed BALB/c-3T3 and tumor cell lines by random amplified polymorphic DNA analysis

Our earlier studies using random amplified polymorphic DNA (RAPD) analysis have shown genetic instability in human lung cancer tissues. Here we have investigated the potential for genetic instability in silica- and cadmium chloride (CdCl2)-transformed BALB/c-3T3 cell lines. Non-transformed, transformed BALB/c-3T3 cells, and tumor cell lines (obtained by injecting nude mice with transformed cell lines) were analyzed for genomic changes. DNAs from 10 different transformed clones and their corresponding tumor cell lines were amplified individually by RAPD analysis using 10 arbitrary primers. DNA from non-transformed BALB/c-3T3 cells was used as a control to compare genetic alterations, if any, between non-transformed, transformed and tumor cell populations. PCR products from RAPD were electrophoretically separated on agarose gels and the banding profiles were visualized by ethidium bromide staining. Five of the 10 primers tested revealed genomic changes in silica-transformed cell lines when compared to non-transformed BALB/c-3T3 cells. Comparison of all 10 transformed and tumor cell lines showed varied degrees of genomic changes using all 10 primers. CdCl2-transformed cell lines displayed fewer genomic changes, only three of 10 primers showed a positive result. CdCl2-transformed cells and their corresponding tumor cell lines showed specific banding pattern differences in six of the 10 samples tested with six of the 10 primers. Changes in band intensity were the most commonly observed changes both in silica- and CdCl2-transformed and tumor cell lines. The results seem to indicate a progressive change in genomic rearrangements which may directly or indirectly be associated with progression of tumorigenesis.