Probing for common rearrangements in South African oesophageal squamous cell carcinoma cell lines by dual and multiple colour fluorescent in situ hybridisation
Oesophageal squamous cell carcinoma (OSCC) is a common cancer in South Africa (SA), ranking second most common in black males resulting in a high mortality rate. The precise mechanisms of development and progression of this disease are still unclear and the identification of genetic changes associated with these tumours may shed light on its pathophysiology and aetiology in SA.
Purpose: Our aim was to probe for common chromosomal rearrangements and “hot spots” using molecular cytogenetic tools in five SA OSCC cell lines; WHCO1, WHCO3, WHCO5, WHCO6 and SNO. METHODS: M-FISH (multicolour fluorescence in situ hybridisation) and dual colour FISH were used to identify and characterise rearrangements.
Results: M-FISH revealed that chromosomes 3,8,9,11,12,13 and 22 were highly involved in inter-chromosomal translocations and were hot spots for rearrangements. A translocation between chromosomes 1 and 3 was seen in 2 cell lines. Further characterisation showed that a common breakpoint on 1p11 might be involved in this rearrangement. Translocations involving 3 and 22 as well as 5 and 19 were both seen in 2 cell lines. Further investigation of these recurrent breakpoints will be necessary. The EGFR (epidermal growth factor receptor) locus is frequently increased in DNA copy number or RNA expression in oesophageal carcinoma. Increased expression was previously documented in three of the cell lines. Using an EGFR specific probe, a large amplification unit encompassing EGFR was observed in one cell line.
Conclusion: Investigation of OSCC by M-FISH has rarely been performed. We compared our results to studies done in the East where this cancer is also prevalent as well as to CGH data previously published. This study contributes to the establishment of a genomic profile of this debilitating disease.