Search

The molecular events involved in prostate cancer progression are, at present, poorly understood. Using a differential display technique, we identified a cDNA fragment that is present in greater abundance in stage D prostate tumors compared to stage B tumors. Northern analysis was used to confirm that transcripts for this gene are expressed at higher levels in prostate tumors of later pathological stage and higher Gleason grade compared to tumors of earlier stage and lower grade. These transcripts were also expressed at high levels in all four human prostate cancer cell lines, the neonatal prostate cell line FNC 267beta1, and in a variety of other normal human adult and fetal tissues. The cDNA fragment obtained by differential display was used as a probe to clone the full-length cDNA for this gene from a human heart cDNA library. DNA sequence analysis confirmed that the cDNA was novel, and we have named this gene CLAR1. The gene displays two transcripts of 2.6 and 2.0 kb in all tissues examined. CLAR1 maps to chromosome 19q13.3 and appears highly conserved among mammals. The deduced amino acid sequence of CLAR1 encodes a proline-rich protein that contains several SH3-binding domains and a serine phosphorylation site. The presence of these motifs suggests a possible role for CLAR1 in one or more signal transduction pathways. The enhanced expression of this novel gene in more advanced forms of prostate cancer and its potential role in signal transduction both argue that this gene should be further investigated.

The androgen receptor (AR) contains glutamine (CAG) and glycine (GGC) repeats that are each polymorphic in length. We screened clinically localized prostate cancers for somatic mutations in the length of the CAG and GGC repeats in the AR gene and characterized the length of these repeats in the germ-line AR gene. Somatic mutations were rare, and the range of germ-line repeat lengths in men with prostate cancer was within the range of normal in the general population. Most allele frequencies in Caucasian men with clinical prostate cancer were remarkably comparable to those in the general Caucasian population. However, a subpopulation of the men with clinical prostate cancer had a substantially higher frequency of AR alleles with 16 or 17 CAGs (6 of 59 men, 10%) than did the general population (6 of 370 alleles, 1.6%), and a different subpopulation of the men with prostate cancer had a higher frequency of AR alleles with 12 or 13 GGCs (7 of 54 men, 13%) than did the general population (1 of 110 alleles, 0.9%). Of the men with prostate cancer who had an AR gene with 16 or 17 CAGs, 83% had lymph node-positive disease, despite the lack of clinical evidence of metastatic spread. This suggests that a short AR CAG allele may be a risk factor for the development of clinically unsuspected lymph node-positive prostate cancer among men undergoing radical prostatectomy and raises the question of whether this short repeat length played an active role in the development of aggressive prostate cancer. The odds of having a germ-line AR gene with a short CAG repeat (