Sotsky Kent T, Yuan Z, Miller A, Weber TK. Deleted in oral cancer-1 expression upregulates proapoptosis elements in microsatellite-unstable human colorectal cancer.
Ann Surg Oncol 2004;
11:192-6. [PMID:
14761923 DOI:
10.1245/aso.2004.03.056]
[Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
BACKGROUND
We previously reported differential expression of the growth suppressor, deleted in oral cancer-1 (DOC-1), in microsatellite-unstable (MSI+) versus microsatellite-stable colorectal cancer (CRC) cell lines. MSI+ CRC cell lines demonstrated decreased DOC-1 expression and decreased apoptosis. Transfection of wild-type DOC-1 into an MSI+ cell line (SW48) resulted in increased apoptosis. We undertook our current experiment to identify specific elements modulated by DOC-1 expression that result in increased apoptosis.
METHODS
SW48 is an MSI+ CRC cell line that does not constitutively express DOC-1. SW48 was suspended in culture medium and incubated to 60% confluence. Half the plates were transfected with cytomegalovirus (CMV)-DOC-1. At 30 hours, RNA and protein were isolated with Trizol. Complementary DNA microarray was performed to compare SW48(CMV-DOC-1) with SW48, which lacks DOC-1. Signal intensity was analyzed by GenePix Pro 3.0 software. Expression ratios </=.67 and >/ 1.5 were considered significant. Poor-quality spots were flagged and excluded from analysis. Real-time polymerase chain reaction was performed to determine DOC-1 levels in both cell lines.
RESULTS
Successful transfection of DOC-1 was confirmed by real-time polymerase chain reaction and by Western blot. Microarray revealed significant differential expression of DOC-1, as expected. Increased DOC-1 expression in SW48(CMV-DOC-1) was associated with significantly increased expression of proapoptosis components of the caspase cascade (CASP7, CASP9) and bcl2/bax pathway (BNIP3, BNIP3L, BID).
CONCLUSIONS
DOC-1 expression promotes apoptosis by upregulation of specific elements of the caspase cascade and bcl2/bax pathways. DOC-1 therefore deserves further study as a candidate for the therapeutic modulation of apoptosis in MSI+ CRC.
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