Mutations of PTEN/MMAC1 in primary prostate cancers from Chinese patients

PTEN/MMACl is a putative tumor suppressor gene located on 10q23, one of the most frequently deleted chromosomal regions in human prostate cancer. Alth ough mutations of PTEN have often been detected in metastases of prostate c ancer, localized tumors have shown lower rates of mutation, which have vari ed from 0 to 20% among different studies. It is unknown whether the rate of PTEN mutations is different in prostate cancer from Asian men compared wit h Western men. To further clarify the role of PTEN in prostate cancer and t o examine the gene for mutations in Asian men, we alanyzed 32 cases of prim ary prostate cancers from Chinese patients, each of whom was not diagnosed by screening with serum prostate-specific antigen, for PTEN mutations using the methods of tissue microdissection, single-strand conformational polymo rphism, and direct DNA sequencing. Seventy % of the tumors were Gleason sco res 8-10, whereas the remainder were Gleason score 7, Six metastases of pro state cancer from American patients were also analyzed. Five of 32 (16%) pr imary prostate cancers from Chinese men and two of six metastases from Amer ican men showed mutations in a total of 10 codons of PTEN, which involved e xons 1, 2, 5, 8, and 9, Two of the mutations were truncation type, whereas the rest were missense mutations. The mutation frequency in these cases fro m Asian patients was higher than that in our previous study of cases in rad ical prostatectomy specimens from American men, in which the 40 primary tum ors were lower grade and had been detected by serum prostate-specific antig en test. We conclude that mutation of PTEN occurs more often in primary pro state cancers of Chinese men, whose tumors are high grade and reflective of an unscreened population.