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Decreased expression of DCC mRNA in human colorectal cancers
1Department of Internal Medicine (Section 1), Sapporo Medical College, Japan.
Abstract:
The mRNA expression levels of DCC gene, which is cloned from the deleted region of chromosome 18q in colorectal cancers and thought to be a tumor-suppressor gene, was evaluated in tissue specimens surgically resected from patients with colorectal cancer by RT-PCR. This method was chosen as the expression level of DCC mRNA is below the detectable level for Northern-blot analysis. Semi-quantitative measurements of DCC mRNA were performed based on a standard curve defined by serial dilution of DCC cDNA. As a result, the expression level of DCC mRNA was found to be lower in 17 out of 30 colorectal cancers than in adjacent non-cancerous tissues. Inclusion of smooth muscle in tissue specimens was observed to have little disturbing effect on comparisons between cancerous and non-cancerous regions. In addition, all 4 specimens of colorectal cancer with liver metastasis showed the decreased expression level of DCC mRNA, suggesting that functional loss of DCC in cancerous tissues may play an important role in metastatic events.
Insights
Downregulated Deleted in Colorectal Carcinoma (DCC) gene mRNA expression was observed in most colorectal cancers compared to normal tissues. This decrease suggests DCC may be crucial in preventing colorectal cancer metastasis.
Area of Science:
- Oncology
- Molecular Biology
- Genetics
Background:
- The Deleted in Colorectal Carcinoma (DCC) gene, located on chromosome 18q, is a candidate tumor-suppressor gene.
- DCC gene alterations are implicated in colorectal cancer development.
Purpose of the Study:
- To quantify mRNA expression levels of the DCC gene in colorectal cancer tissues.
- To investigate the correlation between DCC expression and colorectal cancer metastasis.
Main Methods:
- Reverse Transcription Polymerase Chain Reaction (RT-PCR) was employed to measure DCC mRNA levels due to low expression.
- Semi-quantitative analysis using a standard curve derived from DCC cDNA dilution was performed.
- Comparisons were made between cancerous and adjacent non-cancerous colorectal tissues.
Main Results:
- DCC mRNA expression was significantly lower in 17 out of 30 colorectal cancer specimens compared to adjacent non-cancerous tissues.
- Smooth muscle presence in specimens minimally affected comparative analysis.
- All four colorectal cancer specimens with liver metastasis exhibited decreased DCC mRNA expression.
Conclusions:
- Reduced DCC mRNA expression is a common feature in colorectal cancers.
- Functional loss of the DCC gene may contribute to the metastatic potential of colorectal cancer.