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Phosphorothioated antisense c-myc oligonucleotide inhibits the growth of human colon carcinoma cells
1NCI-NMOB, National Naval Medical Center, Bethesda, MD 20889, USA.
Background:
The functional significance of c-myc overexpression in human colon carcinoma is unclear.
Materials And Methods:
Three human colon carcinoma cell lines, LS174T, SW1116 and SW48, were treated in vitro with phosphorothioate modified antisense oligonucleotides (ASO), complementary to the c-myc translation initiation site, or two control oligonucleotides. Growth was assayed by the methyl tetrazolium (MTT) assay and colony formation. C-myc, retinoblastoma (Rb), carcinoembryonic antigen (CEA), and alkaline phosphatase (AP) expression was assessed by immunoblotting.
Results:
The ASO specifically inhibited growth of all three human colon carcinoma cell lines. Further studies were conducted on LS174T because growth inhibition was associated with a more differentiated morphology. In LS174T cells, ASO caused a dose dependent decrease in c-myc and Rb protein expression, but an increase in CEA and AP expression.
Conclusions:
The growth of human colon carcinoma cells is dependent on c-myc expression, and the inhibition of c-myc expression in LS174T is associated with a more differentiated phenotype.
Insights
Antisense oligonucleotides targeting c-myc suppressed human colon carcinoma cell growth. This inhibition correlated with increased differentiation markers, suggesting c-myc is crucial for colon cancer proliferation.
Area of Science:
- Oncology
- Molecular Biology
- Cell Biology
Background:
- The role of c-myc overexpression in human colon carcinoma remains incompletely understood.
- Investigating oncogene function is critical for developing targeted cancer therapies.
Purpose of the Study:
- To determine the functional significance of c-myc in human colon carcinoma.
- To assess the impact of inhibiting c-myc expression on cancer cell growth and differentiation.
Main Methods:
- Utilized phosphorothioate modified antisense oligonucleotides (ASO) targeting the c-myc translation initiation site in three human colon carcinoma cell lines (LS174T, SW1116, SW48).
- Assessed cell growth via methyl tetrazolium (MTT) assay and colony formation assays.
- Evaluated protein expression of c-myc, retinoblastoma (Rb), carcinoembryonic antigen (CEA), and alkaline phosphatase (AP) using immunoblotting.
Main Results:
- ASO treatment specifically inhibited the growth of all three tested colon carcinoma cell lines.
- In LS174T cells, ASO administration resulted in a dose-dependent reduction of c-myc and Rb protein levels.
- Concurrently, ASO treatment led to increased expression of differentiation markers CEA and AP in LS174T cells.
Conclusions:
- Human colon carcinoma cell proliferation is dependent on c-myc expression.
- Inhibition of c-myc in LS174T cells promotes a more differentiated cellular phenotype, suggesting a therapeutic target.