Abstract 310: Cadherin-dependent modulation of chemosensitivity in oral tumor progression

Abstract

Abstract The progression of healthy oral epithelia to an oral carcinoma often involves aberrant expression of a group of calcium-dependent transmembrane proteins called cadherins. Histological studies of human tumors have demonstrated increased expression of the epithelial-resident placental (P-cadherin) and ectopic expression of the mesenchymal neuronal (N-cadherin) cadherin in oral dysplasia. We hypothesized that these changes in cadherin expression during early oral tumor development could facilitate increases in survival signaling. We genetically modified dysplastic oral keratinocytes to overexpress P-cadherin or suppress endogenous expression of N-cadherin. P-cadherin overexpression and N-cadherin suppression independently elicited a 3-6-fold decrease in apoptosis levels in response to docetaxel treatment compared to similarly treated controls. We found that in untreated dysplastic cells, P- and N-cadherin expression had positive and negative correlations, respectively, with the activation of the survival-associated enzymes focal adhesion kinase (FAK), mitogen-activated protein kinase (MAPK), and AKT kinase. The total levels of nuclear factor kappa B (NFkb) were positively correlated with P-cadherin overexpression and reciprocally correlated with levels of N-cadherin. In docetaxel-treated dysplastic cells, we observed the reverse effect compared to untreated cells: the increased level of N-cadherin was positively correlated with FAK activity whereas FAK activity was suppressed by P-cadherin. P-cadherin expression in docetaxel-treated cells also increased activation of both MAPK and AKT, whereas alteration of N-cadherin levels had no effect. Because N-cadherin levels are known to increase in late-stage oral tumors, we extended these signaling studies to oral squamous carcinoma cells (OSCCs) expressing low or high levels of N-cadherin. In contrast to its suppression of survival pathways in docetaxel-treated dysplastic cells, in docetaxel-treated OSCCs, N-cadherin expression strongly enhanced phosphorylation of MAPK and AKT, and increased expression of NFkb. N-cadherin overexpression during this treatment also increased expression of the antiapoptotic proteins Mcl-1 and suppressed phosphorylation of the apoptotic regulator signal transducer and activator of transcription 3 (pSTAT3). Increase cadherin expression in all untreated cell lines increased expression of an inducer of epithelial to mesenchymal transition, the transmembrane protein mucin-1 (MUC1). N-cadherin overexpression also increased motility in both cell lines. Taken together, our data demonstrate antiapoptotic signaling directed by increased levels of P-cadherin in oral dysplasia and N-cadherin in OSCC, whereas increased levels of N-cadherin in dysplastic cells directed cellular signaling that were associated with a proapoptotic phenotype. Citation Format: Aaron Mody, Cassandra Decker, Kathryn R. Lawson. Cadherin-dependent modulation of chemosensitivity in oral tumor progression [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 310.