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Decreased levels of precursor transforming growth factor beta1 in human colorectal cancer
J Dimberg1, A Hugander, A Sirsjo
1Department of Biomedicine and Surgery, Faculty of Health Sciences, Linköping, Sweden. jan.dimberg@hhj.hj.se
Abstract:
Transforming growth factor (TGF) beta1 is a growth factor with wide-ranging effects on proliferation, differentiation, immunosuppression, apoptosis and matrix remodelling. TGFbeta1 seems to have an antitumorigenic role in the gastrointestinal tract but may also be associated with the development of colorectal cancer. Initially, TGFbeta1 is produced in a latent (precursor) form in epithelial cells and then is activated by a not clearly understood multistep process. In this study, we analysed precursor TGFbeta1 protein expression (n=40) and TGFbeta1 gene expression (n=49) in human colorectal adenocarcinomas and 49 normal adjacent tissue. Out of these 49 normal tissues 40 were matched. Western blot analysis revealed that the precursor TGFbeta1 protein levels were generally lower in colorectal cancerous tissue compared to adjacent non-cancerous tissue (P<0.001). Furthermore, with real-time PCR our results cannot reflect a statistically significant difference in TGFbeta1 gene expression between the tumour tissue and normal tissue. These finds indicate that it is likely that there are mechanisms which control precursor TGFbeta1 protein expression by factor(s) at the level of pre-translation of the TGFbeta1 transcript and/or at the level of post-translation of the TGFbeta1 protein in the tumours. This process may be related to carcinogenesis and poses the question whether the suppression of the precursor TGFbeta1 is an early event, in vivo, in the human colorectal adenoma-carcinoma sequence.
Insights
Transforming growth factor beta1 (TGFbeta1) precursor protein is lower in colorectal cancer. Gene expression showed no significant difference, suggesting post-transcriptional regulation in colorectal carcinogenesis.
Area of Science:
- Molecular Biology
- Oncology
- Gastroenterology
Background:
- Transforming growth factor beta1 (TGFbeta1) is a crucial cytokine involved in cell proliferation, differentiation, apoptosis, and matrix remodeling.
- While TGFbeta1 exhibits antitumorigenic properties in the gastrointestinal tract, its role in colorectal cancer development remains complex and debated.
- TGFbeta1 is initially synthesized as a latent precursor protein that requires activation through a multistep process.
Purpose of the Study:
- To investigate the expression levels of precursor TGFbeta1 protein and TGFbeta1 gene in human colorectal adenocarcinomas compared to adjacent normal tissues.
- To explore potential regulatory mechanisms controlling TGFbeta1 expression during colorectal carcinogenesis.
Main Methods:
- Western blot analysis was employed to quantify precursor TGFbeta1 protein levels in 40 colorectal tumor samples and 40 matched adjacent normal tissues.
- Real-time PCR was utilized to assess TGFbeta1 gene expression in 49 colorectal tumor samples and 49 adjacent normal tissues.
- Statistical analysis was performed to compare protein and gene expression between tumor and normal tissues.
Main Results:
- Precursor TGFbeta1 protein levels were significantly lower in colorectal cancerous tissues compared to adjacent non-cancerous tissues (P<0.001).
- No statistically significant difference in TGFbeta1 gene expression was observed between tumor and normal colorectal tissues.
- These findings suggest post-transcriptional regulation of TGFbeta1 precursor protein in colorectal tumors.
Conclusions:
- The observed decrease in precursor TGFbeta1 protein, without a corresponding change in gene expression, indicates regulatory mechanisms acting at the pre- and/or post-translational levels.
- Suppression of precursor TGFbeta1 may represent an early event in the adenoma-carcinoma sequence of human colorectal cancer.
- Further research is warranted to elucidate the specific factors and pathways involved in TGFbeta1 regulation during colorectal carcinogenesis.