Differential Expression of BMI1 and PARP1 in Reticular, Erosive and Atrophic Oral Lichen Planus

Perks, Alexandra (2024). Differential Expression of BMI1 and PARP1 in Reticular, Erosive and Atrophic Oral Lichen Planus. University of Birmingham. M.Res.

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Abstract

Background: Oral lichen planus (OLP) is an oral potentially malignant disorder (OPMD) with a risk of progression to oral squamous cell carcinoma (OSCC). The erosive and atrophic variants appear to have an increased malignant transformation risk compared to the reticular variant. Cancer stem cell (CSC) marker B cell-specific Moloney murine leukemia virus integration site 1 (BMI1) and DNA repair enzyme Poly (ADP-Ribose) Polymerase 1 (PARP1) have been shown to be upregulated in OSCC.

Objectives: The aims of this study were to identify BMI1 and PARP1 expression patterns in erosive and atrophic OLP compared with reticular OLP. Furthermore we aimed to determine if BMI1 and PARP1 could be used as potential biomarkers for identification of high risk OLP lesions.

Materials and Methods: This was a cross-sectional, observational, pilot study. Patients were prospectively recruited from the Oral Medicine clinic and underwent oral tissue biopsy. 63 paraffin-embedded tissue blocks of histologically confirmed OLP were stained for BMI1 and PARP1 using immunohistochemistry (IHC). BMI1 and PARP1 IHC expression in both the full thickness (FT) and basal half (BH) of the epithelium was analysed using the Immunoreactive Scoring system (IRS).

Results: PARP1 expression was higher than BMI1 expression in both reticular and erosive/atrophic OLP samples. No significant differences were identified between the OLP variants and PARP1 IRS scores for either the FT (p = .858) or the BH of the epithelium (p = .681) or BMI1 scores for either the FT (p = .492) or the BH of the epithelium (p = .649). However there was a small increase in the number of erosive/atrophic OLP samples that had strong PARP1 staining compared to reticular. There was a significant positive correlation seen between BMI1 and PARP1 expression in both the FT (r (61) = .432, p <.001) and the BH of the epithelium (r (61) = .530, p <.001).

Conclusions: Although not significant, PARP1 expression was slightly increased in erosive/atrophic OLP compared to reticular, suggesting a possible association with high risk lesions. Additionally, the findings demonstrated a positive correlation between BMI1 and PARP1 indicating co expression of the proteins in OLP. Further studies with larger sample sizes, negative tissue controls and follow-up data are indicated to determine if BMI1 and PARP1 could be used as potential biomarkers for identification of OLP lesions at high risk for malignant transformation.

Type of Work:

Thesis (Masters by Research > M.Res.)

Award Type:

Masters by Research > M.Res.

Supervisor(s):