RARβ Expression in Keratinocytes from Potentially Malignant Oral Lesions: The Functional Consequences of...

Area of Science:

• Oncology
• Molecular Biology
• Epigenetics

Background:

• Retinoid chemoprevention trials for oral potentially malignant lesions (PMOLs) have yielded disappointing results.
• Loss of Retinoic Acid Receptor beta 2 (RARβ2) expression via promoter methylation is an early event in oral carcinogenesis.
• Understanding RARβ loss mechanisms is crucial for improving retinoid efficacy.

Purpose of the Study:

• To investigate the effects of all-trans retinoic acid (ATRA) and 5-Aza-2' deoxycytidine (5-AZA-CdR) on immortalized PMOL (iPMOL) cell cultures.
• To assess RARβ expression, cell cycle, and senescence following treatment.
• To correlate findings with RARβ-promoter methylation status.

Main Methods:

• Immunohistochemistry to assess RARβ expression in PMOL tissues.
• Treatment of iPMOL cell cultures with ATRA and/or 5-AZA-CdR.
• Cell cycle analysis and senescence assessment post-treatment.

Main Results:

• RARβ expression was variable in PMOL tissues, lower in those yielding immortal cell lines.
• ATRA alone had minimal effect on RARβ expression; 5-AZA-CdR significantly increased it.
• Cell cycle and senescence responses were variable, potentially influenced by 5-AZA-CdR's broader effects.

Conclusions:

• The response of iPMOL cells to ATRA and 5-AZA-CdR is variable and depends on factors like RARβ-promoter methylation.
• These findings may explain the inconsistent efficacy of retinoids in PMOLs observed in chemoprevention trials.