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Oral squamous cell carcinoma (OSCC) is worldwide health problem associated with high morbidity and mortality. From both the patient and socioeconomic perspectives, prevention of progression of premalignant oral intraepithelial neoplasia (OIN) to OSCC is clearly the preferable outcome. Optimal OSCC chemopreventives possess a variety of attributes including high tolerability, bioavailability, efficacy and preservation of an intact surface epithelium. Terminal differentiation, which directs oral keratinocytes leave the proliferative pool to form protective cornified envelopes, preserves the protective epithelial barrier while concurrently eliminating growth-aberrant keratinocytes. This study employed human premalignant oral keratinocytes and an OSCC cell line to evaluate the differentiation-inducing capacity of the synthetic retinoid, fenretinide (4HPR). Full-thickness oral mucosal explants were evaluated for proof of concept differentiation studies. Results of this study characterize the ability of 4HPR to fulfill all requisite components for keratinocyte differentiation, i.e. nuclear import via binding to cellular RA binding protein-II (molecular modeling), binding to and subsequent activation of retinoic acid nuclear receptors (receptor activation assays), increased expression and translation of genes associated with keratinocyte differentiation [Reverse transcription polymerase chain reaction (RT-PCR), immunoblotting] upregulation of a transglutaminase enzyme essential for cornified envelope formation (transglutaminase 3, functional assay) and augmentation of terminal differentiation in human oral epithelial explants (image-analyses quantified corneocyte desquamation). These data build upon the chemoprevention repertoire of 4HPR that includes function as a small molecule kinase inhibitor and inhibition of essential mechanisms necessary for basement membrane invasion. An upcoming clinical trial, which will assess whether a 4HPR-releasing mucoadhesive patch induces histologic, clinical and molecular regression in OIN lesions, will provide essential clinical insights. [ABSTRACT FROM AUTHOR]

Introduction: Oral squamous cell carcinoma (OSCC), is associated with high morbidity and mortality. Preemptive interventions have been postulated to provide superior therapeutic options, but their implementation has been restricted by the availability of broadly applicable local delivery systems. Methods: We address this challenge by engineering a delivery vehicle, Janus nanoparticles (JNP), that combine the dual mucoadhesive properties of a first cationic chitosan compartment with a second hydrophobic poly(lactide-co-glycolide) release compartment. JNP are designed to avoid rapid mucus clearance while ensuring stable loading and controlled release of the IL-6 receptor antagonist, tocilizumab (TCZ). Results: The JNP featured defined and monodispersed sizes with an average diameter of 327 nm and a PDI of 0.245, high circularities above 0.90 and supported controlled release of TCZ and effective internalization by oral keratinocytes. TCZ released from JNP retained its biological activity and effectively reduced both, soluble and membrane-bound IL-6Rα (71% and 50%). In full-thickness oral mucosal explants, 76% of the JNP breached the stratum corneum and in 41% were observed in the basal cell layer indicating excellent mucopenetrating properties. When tested in an aggressive OSCC xenograft model, TCZ-loaded JNP showed high levels of xenograft inhibition and outperformed all control groups with respect to inhibition of tumor cell proliferation, reduction in tumor size and reduced expression of the proto-oncogene ERG. Conclusion: By combining critically required, yet orthogonal properties within the same nanoparticle design, the JNP in this study, demonstrate promise as precision delivery platforms for intraoral field-coverage chemoprevention, a vastly under-researched area of high clinical importance. [ABSTRACT FROM AUTHOR]

Basement membrane invasion defines malignant transformation of surface premalignancy. Treatment of oral squamous cell carcinoma (OSCC) cells with the synthetic vitamin A derivative, fenretinide (4HPR), induces numerous cancer-preventive effects including suppression of basement membrane invasion, elimination of anchorage-independent growth, disruption of actin cytoskeletal components and inhibition of the invasion-enabling focal adhesive kinase. The purpose of this study was to elucidate 4HPR's effects on additional invasion-relevant mechanisms including matrix metalloproteinase (MMP) activation and function, cell–extracellular matrix (ECM) attachments and interaction with a kinase that is essential for the epithelial–myoepithelial transformation i.e. c-Jun NH2-terminal kinase (JNK). Our data revealed that 4HPR binds with high affinity to the ATP-binding site of all three JNK isoforms with concurrent suppression of kinase function. Additional studies showed 4HPR treatment inhibited both OSCC cell–ECM adhesion and MMP activation and function. JNK downregulation and induced expression studies confirmed that the JNK3 isoform conveyed that largest impact on OSCC migration and invasion. Biodegradable polymeric implants formulated to preserve 4HPR's function and bioavailability were employed to assess 4HPR's chemopreventive impact on an OSCC tumor induction model. These studies revealed 4HPR local delivery significantly inhibited OSCC tumor size, mitotic indices and expression of the endothelial marker, erythroblast transformation-specific-related gene with concurrent increases in tumor apoptosis (cleaved caspase-3). Collectively, these data show that 4HPR suppresses invasion at multiple sites including 'outside-in' signaling, cell–ECM interactions and suppression of MMPs. These functions are also essential for physiologic function. Regulation is therefore essential and reinforces the pharmacologic advantage of local delivery chemopreventive formulations.. [ABSTRACT FROM AUTHOR]

Local, long-acting release fenretinide (4HPR) millicylindrical implants were prepared and evaluated for their release kinetics in vivo and their ability to suppress oral cancer tumor explant growth. Poly(lactic- co -glycolic acid)(PLGA) implants were prepared as a function of drug loading and the presence of various excipients (pore-formers, solubilizers, crystallization inhibitors) to enhance release of the insoluble 4HPR. Release kinetics and bioerosion of PLGA were monitored both in vitro in a PBS/Tween 80 buffer and in vivo by recovery of the drug remaining at the injection site. 4HPR was released from PLGA implants much slower in vivo than in the drug solubilizing media in vitro , with a 3-week lag phase and continuous release of >2 months, but showed some release enhancement by addition of solubilizers. Water-soluble PVA/sucrose implants for release of 4HPR served to determine if drug dissolution provided suitable controlled release without the PLGA, and this formulation showed continuous drug release over 6 weeks in vivo. Placement of PLGA-4HPR implants adjacent to oral cancer tumor murine xenografts showed inhibition of tumor growth relative to sham implants, indicating the potential for the local 4HPR delivery approach to be useful for oral cancer chemoprevention. [ABSTRACT FROM AUTHOR]

Summary: Detection of DNA methylation has produced promising results as biomarkers for head and neck squamous cell carcinoma (HNSCC). However, current panels are limited by an insufficient number of sensitive and specific tumor markers. MicroRNAs (miR) play an important role in tumorigenesis, and may represent a novel panel of molecules for the development of cancer biomarkers. We investigated methylation of three miRNA promoter sites of miR-9 (miR-9-1, miR-9-2, miR-9-3) in 107 human head and neck tissue samples and controls. We found methylations of miR-9-1 and miR-9-3 were higher in oral and oropharyngeal carcinomas than that in laryngeal carcinoma, achieving a combined sensitivity of 63% and 56%, respectively, for these two tumor types, compared to 21% for the laryngeal carcinoma. Quantitative PCR of miR-9 showed reduced expression associated with methylation of miR-9 in tumor tissues. To investigate the functional consequences of miR-9 methylation, we found that miR-9 methylation is correlated with miR-9 expression level in human HNSCC cell lines. Demethylation treatment using 5-aza-deoxycytidine restored its expression in a miR-9 methylated human HNSCC cell line UM-SCC22A. Furthermore, cell proliferation and viability was significantly inhibited, while PTEN expression was elevated after transfection of miR-9 into the UM-SCC22A cell line. In summary, our results suggest that methylations of miR-9-1 and miR-9-3 are sensitive and specific biomarkers for HNSCC, particularly for oral and oropharyngeal squamous cell carcinomas. In addition, miR-9 may function as a tumor suppressor in HNSCC through inhibition of cell proliferation and elevation of tumor suppressor PTEN. [ABSTRACT FROM AUTHOR]