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Interleukin 4 down-regulates expression of c-kit and autocrine stem cell factor in human colorectal carcinoma cells
1Swiss Institute for Experimental Cancer Research, Department of Cellular Biology, Epalinges, Switzerland.
Abstract:
Stem cell factor (SCF) is a cytokine which plays an important role in the development of precursor cells. We have investigated the expression of SCF and its receptor, the c-kit proto-oncogene, in human colorectal carcinoma cell lines. Using reverse transcription-PCR, we confirmed the expression of c-kit in two lines (LS174T and LS1034) and of SCF in 9 of 11 cell lines tested. In a Northern blot, a single transcript of 6.6 kb was detected for SCF mRNA. In addition, two lines (LS174T and HT29) synthesized SCF protein, as detected by Western blot analysis. SCF stimulated proliferation and colony formation of LS174T in a dose-dependent manner up to 160%. A half-maximal effect was obtained with about 5.5 ng/ml of SCF under both growth conditions. LS174T cells expressed the M(r) 145,000 c-kit protein on the cell surface and a neutralizing anti-c-kit mAb inhibited colony formation of LS174T by 40%. Interleukin 4 (IL-4) completely inhibited SCF-induced proliferation of LS174T cells. Interestingly, IL-4 induced an almost complete down-regulation of both c-kit and SCF expression in LS174T. Our findings suggest that in LS174T cells, an SCF-mediated autocrine loop is functional and that IL-4 down-regulates the expression of both the receptor and the ligand of this circuit.
Insights
Stem cell factor (SCF) drives colorectal cancer cell growth via an autocrine loop. Interleukin 4 (IL-4) inhibits this growth by down-regulating both SCF and its receptor, c-kit.
Area of Science:
- Oncology
- Cell Biology
- Molecular Biology
Background:
- Stem cell factor (SCF) is a crucial cytokine for precursor cell development.
- The c-kit proto-oncogene encodes the receptor for SCF.
- SCF and c-kit play roles in various cellular processes, including proliferation.
Purpose of the Study:
- To investigate the expression of SCF and c-kit in human colorectal carcinoma cell lines.
- To determine the functional role of the SCF/c-kit pathway in colorectal cancer cell growth.
- To explore the effect of Interleukin 4 (IL-4) on SCF/c-kit signaling in these cells.
Main Methods:
- Reverse transcription-PCR (RT-PCR) for gene expression analysis.
- Northern blot to detect SCF mRNA transcripts.
- Western blot analysis for SCF protein detection.
- Cell proliferation and colony formation assays.
- Use of neutralizing anti-c-kit monoclonal antibody (mAb).
Main Results:
- SCF expression was detected in 9 of 11 colorectal cancer cell lines.
- c-kit expression was confirmed in LS174T and LS1034 cell lines.
- SCF significantly stimulated proliferation and colony formation of LS174T cells in a dose-dependent manner.
- SCF/c-kit signaling was implicated in LS174T cell growth, with a neutralizing anti-c-kit mAb inhibiting colony formation.
- Interleukin 4 (IL-4) completely inhibited SCF-induced proliferation and down-regulated both c-kit and SCF expression in LS174T cells.
Conclusions:
- An SCF-mediated autocrine loop is functional in LS174T colorectal cancer cells.
- IL-4 effectively inhibits SCF-induced proliferation by down-regulating both SCF and its receptor, c-kit.
- These findings highlight the potential of targeting the SCF/c-kit pathway and its regulation by IL-4 in colorectal cancer therapy.