Gastric cancer is one of the major causes of death due to cancer in the world. It is a multi-factorial disease with epigenetic factors being also involved in its development. FAT4 is a tumor suppressor gene exerting an important role in cell adhesion. This study aimed at analyzing FAT4 expression and promoter methylation in gastric cancer. FAT4 expression was studied in 30 tumoral tissues and their non-tumoral counterparts using Taqman real time PCR method. Promoter methylation was assessed using bisulfite conversion method followed by sequencing. Tumor tissues showed reduced FAT4 expression (P = 0.04). FAT4 downregulation was associated with tumor grade, with higher repression at advanced grades. Significant increase of promoter methylation was observed in tumoral tissues. Reduced expression of FAT4 and increased methylation of its promoter may be one of the effective processes in turning a healthy stomach tissue into a tumor tissue.

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In silico analysis is the most important approach to understand protein structure and functions, and the most important problem for designing and producing a fusion construct is producing large amounts of functional protein. Clostridium perfringens type A and Clostridium septicum produce alpha (plc) and alpha toxins respectively. C. perfringens can cause gas gangrene and gastrointestinal diseases. C. septicum can cause traumatic and non-traumatic gas gangrene. The aim of current research was in silico analysis of a chimeric fusion protein against C. perfringens type A and C. septicum alpha toxins. Firstly, the chimeric fusion gene was designed according to nucleotide sequences of C. perfringens type A alpha (KY584046.1) and C. septicum alpha (JN793989.2) toxin genes and then its fusion protein is constructed by amino acid sequences of C. perfringens type A and C. septicum alpha toxins. Secondly, online software was used to determine prediction of secondary and tertiary structures and physicochemical characteristics of the fusion protein. Finally, the validation of the fusion protein was confirmed by Rampage and proSA program. The designed fusion protein has 777 amino acids in length. TASSER server and physicochemical parameters are showed: C-score = − 2.68 and molecular weight = 87.9 KD respectively. Rampage and proSA software revealed the fusion protein is valid. Deposited accession number for the sequence of the fusion gene in the GenBank is MK908396. The designed fusion protein is valid and functional. Thus, the fusion gene could be used for clone and expression in a proper prokaryotic cell and also as a recombinant vaccine candidate.