Human MutL homolog 1 immunoexpression in oral leukoplakia and oral squamous cell carcinoma: A prospective study in Indian population
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Updated: Mar 13, 2026
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Narendra T Chaudhari1, Jagdish V Tupkari1, Tabita Joy1
1Department of Oral Pathology and Microbiology, Government Dental College and Hospital, Mumbai, Maharashtra, India.
Background:
Mammalian mismatch repair system is responsible for maintaining genomic stability during repeated duplications, and human MutL homolog 1 (hMLH1) protein constitutes an important part of it. Various isolated studies have reported the altered expression of hMLH1 in oral leukoplakia (OL) and oral squamous cell carcinoma (OSCC). Research is lacking in the quantitative estimation and comparison of hMLH1 expression in OL and OSCC.
Aims:
To evaluate, quantify and compare hMLH1 immunoexpression in normal oral mucosa, OL and OSCC.
Settings And Design:
Thirty patients of OL and thirty patients of OSCC formed the study group and thirty patients were included in the control group (normal oral mucosa). Formalin-fixed paraffin wax blocks were prepared from the tissue samples.
Materials And Methods:
Immunohistochemistry for hMLH1 was performed, and the total number of positive cells was counted in high-power fields, and based on that percentage positivity of hMLH1 was calculated in all the cases.
Statistical Analysis:
Kruskal-Wallis and t-test were used. P < 0.05 was considered to be statistically significant.
Results:
The mean hMLH1 value in control group, leukoplakia and OSCC was 78.26, 54.33 and 40.97 respectively. hMLH1 immunoexpression showed decreasing indexes from control group to leukoplakia and then further to OSCC. hMLH1 expression was significantly lower in OSCC as compared to leukoplakia. There was no significant correlation of mean hMLH1 expression between different clinical and histopathological stages of leukoplakia and OSCC.
Conclusions:
hMLH1 immunoexpression was inversely related to the degree of dysplasia. These findings suggest that there is a progressive decrease in hMLH1 expression from control to leukoplakia and further to OSCC. Thus, it can be concluded that hMLH1 can be used as a reliable biomarker for malignant transformation.
Insights
Human MutL homolog 1 (hMLH1) expression decreases progressively from normal oral mucosa to oral leukoplakia and oral squamous cell carcinoma. Lower hMLH1 levels in oral cancer suggest its potential as a biomarker for malignant transformation.
Area of Science:
- Genomic stability and DNA repair mechanisms.
- Cancer biology and molecular pathology.
Background:
- The mismatch repair system maintains genomic stability.
- Human MutL homolog 1 (hMLH1) is crucial for this system.
- Altered hMLH1 expression is noted in oral lesions, but quantitative data is limited.
Purpose of the Study:
- To quantify and compare hMLH1 immunoexpression in normal oral mucosa, oral leukoplakia (OL), and oral squamous cell carcinoma (OSCC).
- To assess the role of hMLH1 in oral carcinogenesis.
Main Methods:
- Immunohistochemistry was used to evaluate hMLH1 expression in 30 OL, 30 OSCC, and 30 control (normal mucosa) tissue samples.
- Percentage positivity of hMLH1 was calculated by counting positive cells in high-power fields.
- Statistical analysis included Kruskal-Wallis and t-tests.
Main Results:
- Mean hMLH1 expression was 78.26 in controls, 54.33 in OL, and 40.97 in OSCC.
- A significant decrease in hMLH1 expression was observed from normal mucosa to OL and further to OSCC.
- hMLH1 expression was significantly lower in OSCC compared to OL.
Conclusions:
- hMLH1 immunoexpression is inversely related to the degree of dysplasia in oral tissues.
- Progressive decrease in hMLH1 expression from normal to precancerous and cancerous lesions is evident.
- hMLH1 serves as a reliable biomarker for monitoring malignant transformation in oral tissues.
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