Reduction in the local expression of complement component 6 (Cd) and 7 (C7) mRNAs in oesophageal carcinoma

Differential displays of tumour/normal pair specimens of human oesophagus i dentified complement component 7 (C7) as being enhanced in normal tissues, but remarkably reduced in carcinoma tissues. In situ hybridisation confirme d the localisation of C7 mRNA in normal oesophageal epithelial cells and it s disappearance in tumour cells. When mRNA expressions of other components were examined by means of semi-quantitative reverse transcriptase-polymeras e chain reaction (RT-PCR) in 10 tumour/normal pair specimens, significant r eductions in C6 and C7 mRNAs were observed, while C3 and C5 mRNAs were enha nced in both normal and tumour tissues. A similar reduction was observed in colon and kidney cancers using the tumour/normal expression array analysis . Gene deletion of C7 was not found in the cell lines by Southern blot anal ysis. Our findings suggest a possible relationship between oesophageal tumo rigenesis and reduced expression of C6 and C7 mRNAs, which is probably caus ed by a change in gene expression regulation and not by genetic loss of the locus. (C) 2001 Elsevier Science Ltd. All rights reserved.