Preferential 8q24 Allelic Imbalance and MYC gene Copy Number in Primary Prostate Cancer

Four independent regions within 8q24 near the MYC gene are associated with risk for prostate cancer. Here we investigated allelic imbalance at 8q24 risk variants and MYC gene DNA copy number (CN) in 27 primary prostate cancers. Heterozygotes were observed in 24 of 27 patients at one or more 8q24 markers and 27% of the loci exhibited AI in tumor DNA. 8q24 risk alleles were preferentially favored in the tumors. Increased MYC gene CN was observed in 33% of tumors, and the co-existence of increased MYC gene CN with AI at risk loci was observed in 86% (P<0.004 exact binomial test) of the informative tumors. No AI was observed in tumors which did not reveal increased MYC gene CN. Higher Gleason score was associated with tumors exhibiting AI (P=0.04), and also with increased MYC gene CN (P=0.02). Our results suggest that AI at 8q24 and increased MYC gene CN may both be related to high Gleason score in prostate cancer. Our findings also suggest that these two somatic alterations may be due to the same preferential chromosomal duplication event during prostate tumorigenesis.