Adenovirus-mediated expression of both antisense ODC and AdoMetDC inhibited colorectal cancer cell growth in vitro.

Aim: To construct a recombinant adenovirus that can simultaneously express both antisense ornithine decarboxylase (ODC) and adenosylmethionine decarboxylase (AdoMetDC) and detect its inhibitory effect on the intracellular polyamine pool and colorectal cancer cell growth. Methods: A205-bp cDNA of AdoMetDC was reverse-inserted into recombinant pAdTrack-ODCas vectors and recombined with pAdEasy-1 vectors in AdEasy-1 cells. Positive clones were selected and transfected into the packaging cell HEK293 after they were linearized by PacI. Green fluorescent protein expression was used to monitor the process of adenovirus packaging. The ODC and AdoMetDC protein levels were identified by western blotting, and intracellular polyamine content was detected by reverse-phase high performance liquid chromatography. A viable cell count was used to determine the growth of HT-29 cells with or without exogenous polyamine. Results: Sequencing confirmed that AdoMetDC cDNA was successfully ligated into the pAdTrack-ODCas vector. GFP expression in 293 cells during virus packing and amplification was observed by fluorescence microscopy. Western blotting demonstrated that both ODC and AdoMetDC were downregulated by Ad-ODC-AdoMetDCas, and consequently 3 kinds of polyamine (putrescine, spermidine and spermine) were reduced to very low levels. HT-29 cell growth was significantly inhibited as compared with control conditions, and growth arrest was not reversed by exogenous putrescine. Conclusion: The successfully constructed recombinant adenovirus, Ad-ODC-AdoMetDCas, blocked polyamine synthesis and has therapeutic potential for treating colorectal cancer in vitro. [ABSTRACT FROM AUTHOR]