Chemopreventive effects of a bioadhesive berry gel on lesions of oral epithelial dysplasia

Abstract

LB-175

Early detection of precancerous oral lesions combined with effective local intervention is a rational strategy to prevent lesion progression to squamous cell carcinoma (SCC). This study assessed therapeutic efficacy of a topically applied bioadhesive gel that contains 10% (w/w) freeze dried black raspberries on oral dysplastic lesions. Patients with histories of recurrent oral dysplastic lesions were targeted for enrollment into the trial. None of the participants were current smokers, or had used tobacco within 6 weeks of study participation. Each patient served as their own internal control. The oral lesions were hemisected, leaving half of the lesional tissue in situ for treatment (topical application q.i.d. for six weeks, 1 gram total daily dose) with the berry gel. Evaluative parameters included: histopathologic diagnoses, image analysis quantified immunohistochemistry (IHC), modulation of gene expression (microarray analyses), and return of heterozygosity. A representative portion of the initial and post treatment biopsy was submitted for light microscopy (to confirm the diagnosis and IHC studies) while the remainder was snap frozen for microarray analyses, RT-PCR validation, and loss of heterozygosity studies. Histopathological diagnoses were provided by two board certified oral pathologists. The summary of pre and post treatment microscopic diagnoses for the 17 persons who completed the study is: no change in microscopic diagnosis=6, increase in lesional grade=4, decrease in lesional grade=7. One participant, who had received 3 previous diagnoses of mild epithelial dysplasia at the treatment site, had complete lesional regression. IHC revealed that 11 of the 14 tissues analyzed showed a decrease (mean=21% ± 4 s.e.m.) in cyclooxygenase 2 (COX-2) protein following treatment (p<0.05, Chi Square). Six of the 7 participants who showed a decrease in histologic grade also showed a decrease in COX-2 protein. Nine of 15 tissues analyzed demonstrated a post treatment decrease (16.9% + 3.9) in epithelial iNOS; 6 of these 9 tissues also showed a decrease in histologic grade. Microarray analyses revealed a post treatment: 1) decrease in expression in all 13 tissues analyzed in genes associated with inhibition of apoptosis, recycling of growth factors, chromosomal rearrangement, and RNA processing, and an 2) increase in expression of genes associated with keratinocyte cornified envelope formation/terminal differentiation, cell adhesion, apoptosis, cytoprotection and negative control of cell growth and division. Ongoing RT-PCR analyses showed increased expression of genes such as desmocollin and cytokeratin 2 associated with keratinocyte differentiation. These data show that despite a short (6 week) duration, berry gels demonstrate chemopreventive efficacy, which results in stable or improved grade in 76% of the oral lesions. Research supported by NIH R21 CA11121.