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Identification and cloning of human G-protein gamma 7, down-regulated in pancreatic cancer
Abstract:
Differentially expressed genes between normal and cancer tissues of the pancreas were investigated using differential display. Consequently, we identified a fragment cDNA that was expressed in the normal tissue but was rarely expressed in the cancer tissue. This cDNA was screened in cDNA library prepared from the normal pancreatic tissue by rapid amplification of cDNA ends (5'RACE). 859 bp of cDNA was cloned and sequenced, and the inferred amino acid sequence was found to encode a G protein gamma subunit with 98% homology to cow G protein gamma 7 and complete homology to human G protein gamma 7. The decreased expression of the G protein gamma 7 was confirmed by Northern blot assay in twelve pancreatic malignancies which included nine duct cell carcinomas, two cystoadenocarcinomas and one blastoma. Reverse transcriptase (RT)-polymerase chain reaction (PCR) assay showed no expression of G protein gamma 7 in five of six pancreatic carcinoma cell lines and two pancreatic cancer tissues. Immunohistochemical analysis also displayed positive staining in the normal tissue but no staining in the cancer tissue. The findings demonstrated that the reduced or suppressed expression of human G-protein gamma 7 may play an important role in pancreatic carcinogenesis.
Insights
Researchers found that the G protein gamma 7 gene is significantly downregulated in pancreatic cancer. This reduced expression of G protein gamma 7 may be a key factor in the development of pancreatic cancer.
Area of Science:
- Molecular Biology
- Oncology
- Genetics
Background:
- Gene expression differences between normal and cancerous pancreatic tissues are crucial for understanding pancreatic carcinogenesis.
- Identifying novel genes involved in cancer development can lead to new diagnostic and therapeutic strategies.
Purpose of the Study:
- To identify genes differentially expressed between normal and pancreatic cancer tissues.
- To investigate the role of a specific G protein gamma subunit in pancreatic cancer development.
Main Methods:
- Differential display and 5'RACE were used to identify and clone a novel cDNA fragment.
- Northern blot, RT-PCR, and immunohistochemical analyses were employed to validate gene expression levels.
- Sequence analysis confirmed homology to human G protein gamma 7.
Main Results:
- A cDNA fragment expressed in normal pancreatic tissue but rarely in cancer tissue was identified.
- The identified cDNA encodes human G protein gamma 7, showing high homology to bovine G protein gamma 7.
- Decreased expression of G protein gamma 7 was confirmed in multiple pancreatic cancer tissues and cell lines.
- Immunohistochemistry revealed G protein gamma 7 protein presence in normal tissue but absence in cancer tissue.
Conclusions:
- Reduced or suppressed expression of human G protein gamma 7 is observed in pancreatic cancer.
- The downregulation of G protein gamma 7 may play a significant role in pancreatic carcinogenesis.
- G protein gamma 7 is a potential biomarker for pancreatic cancer.