Related Experiment Videos
The role of nm23 in transforming growth factor beta 1-mediated adherence and growth arrest
1Laboratory of Gastrointestinal Cancer Research, Memorial Sloan-Kettering Cancer Center, New York, New York 10021.
Abstract:
nm23 has properties of a metastasis suppressor gene and also has been implicated in the control of response to transforming growth factor beta 1 (TGF beta 1) by studies in melanoma cells. In this report, we have examined the role of nm23 in two HT29 colon carcinoma sublines at different stages in tumor progression with different responses to TGF beta 1: the HD3 subline, which shows TGF beta 1-induced growth arrest and differentiation; and the more invasive and tumorigenic U9 subline, which induces tumors 7-fold as large as those induced by HD3 cells with one-half the latency. Analysis by semiquantitative reverse transcription-polymerase chain reaction showed that antisense phosphorothiolated oligonucleotides to the nm23 initiation site (nm23 AS oligos) decreased nm23 mRNA levels 2-8-fold in HD3 and U9 cells when normalized to beta-actin mRNA levels. However, a role for nm23 in TGF beta 1-mediated responses could only be found in HD3 cells. nm23 AS oligos inhibited the differentiation property of cell adherence over 90% in HD3 cells, and this loss of adherence could be partially blocked by concurrent treatment with TGF beta 1. In contrast, U9 cell adherence was not detectably altered by nm23 AS oligos, whether added in the presence or absence of TGF beta 1. The TGF beta 1-induced inhibition of HD3 cell proliferation was blocked by nm23 AS oligos, whereas the TGF beta 1-induced proliferation of U9 cells was unaffected by nm23 AS oligos.(ABSTRACT TRUNCATED AT 250 WORDS)
Insights
The nm23 gene suppresses metastasis and influences transforming growth factor beta 1 (TGF beta 1) responses in colon cancer cells. Its inhibition blocked TGF beta 1-induced differentiation and proliferation in HD3 cells but not in U9 cells.
Area of Science:
- Oncology
- Molecular Biology
- Cell Biology
Background:
- The nm23 gene is recognized for its role as a metastasis suppressor.
- nm23 has been linked to the regulation of responses to transforming growth factor beta 1 (TGF beta 1).
Purpose of the Study:
- To investigate the role of nm23 in the differential responses to TGF beta 1 in two colon carcinoma sublines (HD3 and U9) at varying stages of tumor progression.
- To determine if nm23 mediates TGF beta 1-induced growth arrest, differentiation, and adherence.
Main Methods:
- Utilized two HT29 colon carcinoma sublines: HD3 (exhibiting TGF beta 1-induced growth arrest and differentiation) and U9 (more invasive and tumorigenic).
- Employed semiquantitative reverse transcription-polymerase chain reaction (RT-PCR) to assess nm23 mRNA levels.
- Administered antisense phosphorothiolated oligonucleotides (AS oligos) targeting nm23 to inhibit its expression.
- Assessed cell adherence and proliferation in response to nm23 AS oligos and TGF beta 1.
Main Results:
- nm23 AS oligos reduced nm23 mRNA levels in both HD3 and U9 cells.
- nm23 AS oligos significantly inhibited cell adherence in HD3 cells, an effect partially counteracted by TGF beta 1.
- nm23 AS oligos blocked TGF beta 1-induced growth arrest in HD3 cells.
- nm23 AS oligos did not affect adherence in U9 cells, irrespective of TGF beta 1.
- TGF beta 1-induced proliferation in U9 cells was unaffected by nm23 AS oligos.
Conclusions:
- nm23 plays a critical role in mediating TGF beta 1-induced differentiation and growth arrest in the HD3 colon carcinoma subline.
- The function of nm23 in TGF beta 1 responses appears to be stage-specific, as it was not observed in the more aggressive U9 subline.
- These findings highlight a potential differential role for nm23 in colon cancer progression and response to TGF beta 1 signaling.