Comparative analysis of basaloid and typical squamous cell and carcinoma of the oesophagus: a molecular biological immunohistochemical study

Twenty-three cases of basaloid squamous cell carcinoma (BSCC) and 23 stage- matched pairs of typical squamous cell carcinoma (SCC) of the oesophagus we re investigated for molecular aberrations. Polymerase chain reaction (PCR) was used to detect toss of heterozygosity at the APC, RE, and IZ;ICC gene l oci, while differential PCR was carried out to detect amplification of the CDK4 gene, In addition, the level of expression of the p53 and RE proteins in the tumour tissue was assessed by immunohistochemistry. Loss of heterozy gosity (LOH) at the APC and MCC loci was about twice as common in BSCC as i n SCC (40% vs. 21% and 33% vs. 12%, respectively), with co-existence of LOH at both loci occurring only in BSCC. LOH frequency at the RE gene locus wa s not remarkably different in either BSCC or SCC (20% vs. 24%, respectively ), On immunohistochemistry, accumulation of p53 protein was slightly more f requent in BSCC than in SCC (61%, vs. 52%), whereas the rate of loss of RE protein expression was about equal in both types of carcinoma (9% vs. 13% B SCC and SCC, respectively). There was no detectable amplification of the CD K4 gene in either type of tumour. Although the observed differences did not achieve statistical significance, this work has further highlighted possib le differences between the molecular pathogenesis of BSCC and SCC, Copyrigh t (C) 2000 John Wiley & Sons, Ltd.