High frequency of allelic imbalance at chromosome region 16q22-23 in human breast cancer: Correlation with high PgR and low S phase

Abstract

The loss of genetic material from a specific chromosome region in tumors suggests the presence of tumor-suppressor genes. Loss of heterozygosity (LOH) or allelic imbalance (Al) on the long arm of chromosome 16 is a known event in sporadic breast cancer. To locate the commonly deleted regions, and therefore (a) candidate tumor-suppressor gene(s), a deletion map of chromosome 16 was made, using 10 microsatellite markers on 150 sporadic breast tumors. The 3 smallest regions of overlap (SRO) were detected on the long arm of chromosome 16. Allelic imbalance was observed with at least one marker in 67% of the tumors. One marker, D16S421, at the 16q22-23 region, showed the highest allelic imbalance, 58%. Tumors with and without Al on I bq were tested for correlation with clinico-pathological features of the tumors such as estrogen- and progesterone-receptor content (ER and PgR), age at diagnosis, tumor size, node status, histological type, S-phase fraction, Al on chromosome 3p, and ploidy. A correlation was found between Al on 16q and high PgR content, also low S-phase fraction (99% confidence limits). A comparison of tumors with and without Al at the D16S421 marker locus revealed a slight correlation with high PgR content. The survival data showed no difference between patients with Al on 16q and those with a normal allele pattern on the long arm of chromosome 16.