Rad51C-ATXN7 fusion gene expression in colorectal tumors.
BACKGROUND
Fusion proteins have unique oncogenic properties and their identification can be useful either as diagnostic or therapeutic targets. Next generation sequencing data have previously shown a fusion gene formed between Rad51C and ATXN7 genes in the MCF7 breast cancer cell line. However, the existence of this fusion gene in colorectal patient tumor tissues is largely still unknown.


METHODS
We evaluated for the presence of Rad51C-ATXN7 fusion gene in colorectal tumors and cells by RT-PCR, PCR, Topo TA cloning, Real time PCR, immunoprecipitation and immunoblotting techniques.


RESULTS
We identified two forms of fusion mRNAs between Rad51C and ATXN7 in the colorectal tumors, including a Variant 1 (fusion transcript between Rad51C exons 1-7 and ATXN7 exons 6-13), and a Variant 2 (between Rad51C exons 1-6 and ATXN7 exons 6-13). In silico analysis showed that the Variant 1 produces a truncated protein, whereas the Variant 2 was predicted to produce a fusion protein with molecular weight of 110 KDa. Immunoprecipitation and Western blot analysis further showed a 110 KDa protein in colorectal tumors. 5-Azacytidine treatment of LS-174 T cells caused a 3.51-fold increase in expression of the fusion gene (Variant 2) as compared to no treatment controls evaluated by real time PCR.


CONCLUSION
In conclusion we found a fusion gene between DNA repair gene Rad51C and neuro-cerebral ataxia Ataxin-7 gene in colorectal tumors. The in-frame fusion transcript of Variant 2 results in a fusion protein with molecular weight of 110 KDa. In addition, we found that expression of fusion gene is associated with functional impairment of Fanconi Anemia (FA) DNA repair pathway in colorectal tumors. The expression of Rad51C-ATXN7 in tumors warrants further investigation, as it suggests the potential of the fusion gene in treatment and predictive value in colorectal cancers.
['Kalvala|Arjun|A|', 'Gao|Li|L|', 'Aguila|Brittany|B|', 'Dotts|Kathleen|K|', 'Rahman|Mohammad|M|', 'Nana-Sinkam|Serge P|SP|', 'Zhou|Xiaoping|X|', 'Wang|Qi-En|QE|', 'Amann|Joseph|J|', 'Otterson|Gregory A|GA|', 'Villalona-Calero|Miguel A|MA|', 'Duan|Wenrui|W|']
D000067719:Ataxin-7 D001374:Azacitidine D045744:Cell Line, Tumor D003001:Cloning, Molecular D015179:Colorectal Neoplasms D003198:Computer Simulation D019175:DNA Methylation D004260:DNA Repair D004268:DNA-Binding Proteins D015972:Gene Expression Regulation, Neoplastic D014644:Genetic Variation D006801:Humans D008970:Molecular Weight D015514:Oncogene Proteins, Fusion
Fusion gene Colorectal tumors Rad51C ATXN7 Chromosomal translocation