Clonal Origin Of Multicentric Urothelial Tumors Studied By X-chromosome Inactivation

Objective:Urothelial tumors is the most common malignant in urology field,multicentric tumors has the characteristics of the high relapse rate, high progression rateand high mortality rate, the cloning mechanism with multicentric urothelial tumors hasnot been elucidated at present.X chromosome inactivation patterns in female patients isthe best means of analysis of tumor cell clonal origin state,for which it has the highdegree of genetic stability.This prospective study was designed to study the clonalorigin of urothelial tumors.Methods:33tissue specimens were taken from10cases of female patients withpathologically proven clear urothelial tumors and corresponding normal urothelial.Genomic DNA was extracted. After Hha I digestion of the human androgen receptor(HUMARA), gene fragment was done polymerase chain reaction (PCR) and denaturingpolyacrylamide gel electrophoresis, and stained by silver nitrate for displayingsingle-stranded DNA fragment length,and electrophoretic band was observed andstudied to determine the status of its clonality.Results:33tissue samples were detected with X chromosome inactivation patterns,of which eight cases from fresh tissue, two cases from paraffin sections of tissue,and allthe samples are taken from the10cases of female multifocal of urothelialcarcinoma.HUMARA gene heterozygosity rate (%)=information on cases/all casescome to90.9%(30/33).The same pattern of the X-chromosome inactivation between thetumor samples was noticed in77.8%(7/9) of urothelial tumors patients, while differentpattern of X-chromosome inactivation was also observed in two patient22.2%(2/9).Conclusions:Majority of the multifocal urothelial tumors has same pattern ofX-chromosome inactivation (the common clonal origin),which prompted that thesatellite lesion is the most probably a result of urothelial metastasis.While a small portion of the cases also reveal a different X-chromosome inactivation pattern(thepolyclonal origin),all the tumor foci are occurred independently,this conclusion canexpand the number of cases, to provide a reliable basis for the experiment.