Posted by jayaram in There is numerous application of PCR and since the techniques is comparatively recent, new applications are being added with an amazing speed. We will not discuss the applications which are common and which can easily be imagined by the reader. Instead some of the novel applications of PCR are discussed in this section.
PCR in cancer research
Since clinical markers of predictive value are not available for cancers, PCR is not yet of much diagnostic value for this human malady. However, PCR is being tremendously used to gain insights into the molecular basis of cancer.
The observation that activated ras gene are present in a variety of human tumours has aroused tremendous scientific investigation of the role of these genes in tumorigenesis. In order that ras genes be demonstrated as causative for tumorigenesis and not merely of secondary involvement it is necessary to prove that (A) mutation forms of these genes are consistently associated with a particular tumor type, and (B) mutation in ras genes occur at very early stages of tumorigenesis. Since hotspots of ras mutations are known. PCR can be used to selectively amplify ras gene regions around these codons and the subsequent RFLP (restriction fragment length polymorphism) or sequencing allows demonstration of mutations fairly quickly. Using PCR it has therefore been possible to demonstrate that mutated ras genes can be consistently associated with pancreatic carcinoma, colon adenoma or adenocarcinoma (50%), thyroid follicular carcinoma (50%), and seminoma (40%). PCR has also been successful in demonstrating that mutated ras genes are present in benign adenomas and malignant carcinomas in the same frequency potentiating the belief that ras genes might be causative rather than secondary genes for carcinogenesis. More importantly, chemical carcinogens studies on animals using PCR have been much more useful in demonstrating that ras genes are activated early in carcinogenesis. When 2-day old rats are injected with nitrosomethyl urea, ras mutations in the mammary tissue can be demonstrated as early as at the stage of 15-days. Earliest tumours, however, develop only after onset of puberty.