Phenotypic mismatch repair hMSH2 and hMLH1 gene expression profiles in primary non-small cell lung carcinomas
Dimitra Vageli1, Zoe Daniil, Jubrail Dahabreh
1Department of Pathology, University of Thessalia Medical School, Larissa, Greece. vagelidim@med.uth.gr
Background:
Defects in the human DNA mismatch repair genes (MMR) hMSH2 and hMLH1 are responsible for the development of sporadic and hereditary colorectal cancers. The role of MMR genes in the pathogenesis of lung cancer has not been elucidated. The aim of this study was to address the phenotypic mRNA expression profiles of mismatch DNA repair system in lung cancer.
Materials And Methods:
We evaluated the mRNA levels of the hMSH2 and hMLH1 components of the mismatch DNA repair (MMR) system in 29 unselected frozen pairs of primary non-small cell lung carcinomas (NSCLCs) and their adjacent normal tissue (ANTs) specimens by quantitative real-time PCR analysis relative to housekeeping Porphobilinogen deaminase (hPBGD) mRNA. To simplify and potentially improve the analysis of data, we defined for each individual MMR mRNA two possible phenotypes: a regular (R(2): hMSH2/hPBGD mRNAs> or =1 and R(1): hMLH1/hPBGD mRNAs> or =1) and a reduced (r(2): hMSH2/hPBGD mRNAs<1 and r(1): hMLH1/hPBGD mRNAs<1). The presence of MMR gene expression was evaluated after conversion of the molecular mRNA levels into clinically distinct phenotypic entities by these working criteria, based on the hypothesis that reduced mRNA and protein levels result in lower or non-functional MMR.
Results:
Phenotyping defined four distinct MMR system expression profiles, R(2)R(1), r(2)R(1), R(2)r(1) and r(2)r(1) by ascending tumor progression rate and identified a previously unrecognized disease-associated phenotypic entity (r(2)r(1)). The phenotype-based biological aspects of the MMR system suggested that its two components: (1) function independently and (2) are not directly involved in the onset of the transformation process, since healthy lung tissue was devoid of r(2)r(1) phenotypes.
Conclusion:
These findings link MMR mRNA levels of paired lung tissue specimens to patients' clinical condition and suggest that phenotypic translation of molecular MMR data refines the biology of the MMR system with consequent diagnostic implications in the clinical assessment of lung cancer patients.
Insights
This study investigated DNA mismatch repair (MMR) gene expression in lung cancer, identifying a new phenotypic profile (r(2)r(1)) linked to disease progression. These findings offer diagnostic insights for lung cancer patients.
Area of Science:
- Oncology
- Molecular Biology
- Genetics
Background:
- Defects in DNA mismatch repair (MMR) genes hMSH2 and hMLH1 are implicated in colorectal cancer development.
- The role of MMR genes in lung cancer pathogenesis remains largely unelucidated.
- This study aimed to characterize the mRNA expression profiles of the MMR system in lung cancer.
Purpose of the Study:
- To investigate the mRNA expression profiles of the mismatch DNA repair (MMR) system in non-small cell lung carcinomas (NSCLCs).
- To correlate MMR gene expression phenotypes with tumor progression.
- To explore the diagnostic implications of MMR mRNA levels in lung cancer assessment.
Main Methods:
- Quantitative real-time PCR was used to evaluate mRNA levels of hMSH2 and hMLH1 in NSCLC tissues and adjacent normal tissues.
- A phenotypic classification system (regular 'R' and reduced 'r') was defined for hMSH2 (R(2)/r(2)) and hMLH1 (R(1)/r(1)) based on mRNA levels relative to hPBGD.
- Four distinct MMR phenotypes (R(2)R(1), r(2)R(1), R(2)r(1), r(2)r(1)) were analyzed in relation to tumor progression.
Main Results:
- Four distinct MMR system expression profiles were identified, including a novel disease-associated phenotype (r(2)r(1)).
- The r(2)r(1) phenotype was associated with ascending tumor progression rates.
- The MMR system components appear to function independently and are not directly involved in the initial transformation process, as healthy lung tissue lacked the r(2)r(1) phenotype.
Conclusions:
- MMR mRNA levels in paired lung tissue specimens correlate with patients' clinical status.
- Translating molecular MMR data into distinct phenotypes refines the understanding of MMR system biology.
- These findings have significant diagnostic implications for the clinical assessment of lung cancer patients.
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