Alterations of ALK gene and protein expression in prostatic cancer and its clinical significance

Abstract

To investigate ALK genomic rearrangements and expression in prostate cancer, and their clinical implications. Two hundred and eighty-one cases of prostate cancer were included. ALK gene rearrangements were assessed by FISH in all cases, and ALK protein expression was assessed by immunohistochemistry in 191 cases. The ALK gene was truncated (mostly 5' deletion) in 18 of 281 (6.4%) cases. EML4-ALK fusion gene was not detected. Genomic rearrangement of ALK gene was not statistically associated with Gleason score, age, TNM or baseline PSA level (P > 0.05). In all 18 cases, there were nuclear expression of ALK protein; in 12 cases, the expression was seen in 5%-30% of the tumor cells, and in the remaining 6 cases, the expression was seen in < 5% of the tumor cells. ALK gene rearrangements occurred in 6.4%, of prostate cancer, and these may not be associated with disease progressions. The ALK protein expresses in the nucleus. The EML4-ALK fusion gene was not found in prostate cancer.