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Mutational analysis of Smad7 in human cervical cancer
Ramkumar Hariharan1, Janki Mohan Babu, Rema P
1Department of Molecular Medicine, Rajiv Gandhi Centre for Biotechnology, Kerala State 695 014, India.
Abstract:
Our aim was to carry out mutational analysis of Smad7 exon 4 that codes for the Smad7 MH2 domain in human cervical cancer tissues. This study is warranted since genetic abnormalities of components of the transforming growth factor-beta (TGF-beta)/Smad signaling system have been implicated in a variety of human cancers. Further, Smad7 is an important member of the Smad family that functions as a negative feedback regulator of TGF-beta responses. By direct sequencing, we screened 60 histopathologically confirmed human cervical carcinomas for mutations in exon 4 of Smad7 that encodes the MH2 domain of the protein, a region of the protein believed to be critical for receptor interaction. No mutations or aberrations could be identified in any of the 60 analyzed tumor samples. However, we identified a previously reported, heterozygous, silent G to C variant in codon 391 of Smad7 that was found twice in the set of 60 clinical samples. Thirty of the clinical samples analyzed in the study were positive for the presence of high-risk human papillomavirus (HPV) subtypes, while the rest were oncogenic HPV-negative. The two instances of the silent variant was found in oncogenic HPV-negative samples. We report mutational analysis of Smad7 in cervical cancer for the first time. Mutations and variants of Smad7 are unlikely to be of major significance to the pathogenesis of HPV-induced cervical cancer.
Insights
Mutational analysis of Smad7 exon 4 in cervical cancer revealed no significant mutations. A rare silent variant was found in HPV-negative samples, suggesting Smad7 is not a major factor in HPV-induced cervical cancer development.
Area of Science:
- Oncology
- Molecular Biology
- Genetics
Background:
- Genetic abnormalities in the transforming growth factor-beta (TGF-beta)/Smad signaling pathway are linked to various human cancers.
- Smad7 acts as a negative feedback regulator of TGF-beta signaling, playing a crucial role in cellular responses.
- Understanding Smad7's role in cervical cancer is important due to the pathway's involvement in tumorigenesis.
Purpose of the Study:
- To investigate mutations in exon 4 of the Smad7 gene, which encodes the critical MH2 domain.
- To assess the potential role of Smad7 genetic alterations in the development of human cervical cancer.
- To determine if Smad7 mutations are associated with high-risk human papillomavirus (HPV) infection in cervical cancer.
Main Methods:
- Direct sequencing was employed to screen 60 human cervical carcinoma tissue samples.
- Analysis focused on exon 4 of the Smad7 gene, specifically targeting the MH2 domain.
- Samples were also assessed for the presence of high-risk HPV subtypes.
Main Results:
- No mutations or significant aberrations were detected in Smad7 exon 4 across the 60 analyzed cervical cancer samples.
- A known heterozygous, silent G to C variant at codon 391 of Smad7 was identified in two samples.
- Both instances of the silent variant occurred in human papillomavirus (HPV)-negative cervical cancer samples.
Conclusions:
- Mutational analysis of Smad7 exon 4 in cervical cancer did not reveal any significant mutations.
- The identified silent Smad7 variant was infrequent and found in HPV-negative cases.
- Smad7 mutations and variants are unlikely to be a major contributing factor in the pathogenesis of HPV-induced cervical cancer.
