Chemokine Function in Periodontal Disease and Oral Cavity Cancer

The chemotactic cytokines, or chemokines, comprise a superfamily of polypeptides with a wide range of activities that include recruitment of immune cells to sites of infection and inflammation, as well as stimulation of cell proliferation. As such, they function as antimicrobial molecules and play a central role in host defenses against pathogen challenge. However, their ability to recruit leukocytes and potentiate or prolong the inflammatory response may have profound implications for the progression of oral diseases such as chronic periodontitis, where tissue destruction may be widespread. Moreover, it is increasingly recognized that chronic inflammation is a key component of tumor progression. Interaction between cancer cells and their microenvironment is mediated in large part by secreted factors such as chemokines, and serves to enhance the malignant phenotype in oral and other cancers. In this article, we will outline the biological and biochemical mechanisms of chemokine action in host–microbiome interactions in periodontal disease and in oral cancer, and how these may overlap and contribute to pathogenesis

Human papillomavirus types in oral squamous cell carcinogenesis

The DNAs of human papillomavirus (HPV) types 4, 16 and 18 have been detected in biopsies of normal and malignant human oral mucosa by Southern blot hybridisation and polymerase chain reaction (PCR). By the former technique HPV-4, HPV-16 and HPV-18 DNAs were detected in three separate carcinomas, but only found in adjacent dysplastic and normal tissue by PCR. The PCR technique also allowed detection of HPV-16 and HPV-18 DNA in additional carcinomas and normal samples. The oral HPV-4 DNA has been molecularly cloned and extensive restriction analysis and nucleotide sequencing showed identity with the prototype HPV-4 DNA. The HPV-18 DNA detected by Southern blot hybridisation showed an altered restriction pattern in the El region of the viral genome; however direct nucleotide sequencing of PCR products from the E6 ORF showed no sequence alterations in either normal or malignant samples. HPV-16 DNA detected in one carcinoma by Southern blot hybridisation revealed altered PstI and Hpall restriction patterns as compared with the prototype viral genome. The expected 2.6kb Hpall and 1.55kb PstI bands, which overlap, were absent, and an additional band of reduced molecular weight was visible in the Hpall digest, suggesting that the oral HPV-16 genome had undergone a deletion or rearrangement. In a further two carcinoma samples positive for HPV-16 DNA by PCR, amplification of a late region fragment of the viral genome produced fragments of reduced molecular weight. When these PCR fragments were used as probes, hybridisation was observed to the 1.78kb PstI and 1.81kb Hpall-BamHI bands of HPV-16 DNA, and also (as a smear) to human genomic DNA from both tumour and normal samples. This suggests that the viral DNA in these samples had undergone recombination events with repetitive cellular sequences, perhaps as a prelude to viral integration or as a means of activating cellular genes. A keratinocyte culture (T45) derived from an oral squamous cell carcinoma was found to be non-tumorigenic in vivo. PCR analysis revealed that a proportion of cells in the culture contained HPV-16 early sequences. The establishment of HPV-positive and HPV-negative clones from this culture will provide an excellent system for studying the role of viral and cellular factors in oral squamous cell carcinogenesis

Surface engineering of macrophages with nanoparticles to generate a cell–nanoparticle hybrid vehicle for hypoxia-targeted drug delivery

Tumors frequently contain hypoxic regions that result from a shortage of oxygen due to poorly organized tumor vasculature. Cancer cells in these areas are resistant to radiation- and chemotherapy, limiting the treatment efficacy. Macrophages have inherent hypoxia-targeting ability and hold great advantages for targeted delivery of anticancer therapeutics to cancer cells in hypoxic areas. However, most anticancer drugs cannot be directly loaded into macrophages because of their toxicity. In this work, we designed a novel drug delivery vehicle by hybridizing macrophages with nanoparticles through cell surface modification. Nanoparticles immobilized on the cell surface provide numerous new sites for anticancer drug loading, hence potentially minimizing the toxic effect of anticancer drugs on the viability and hypoxia-targeting ability of the macrophage vehicles. In particular, quantum dots and 5-(aminoacetamido) fluorescein-labeled polyamidoamine dendrimer G4.5, both of which were coated with aminederivatized polyethylene glycol, were immobilized to the sodium periodate-treated surface of RAW264.7 macrophages through a transient Schiff base linkage. Further, a reducing agent, sodium cyanoborohydride, was applied to reduce Schiff bases to stable secondary amine linkages. The distribution of nanoparticles on the cell surface was confirmed by fluorescence imaging, and it was found to be dependent on the stability of the linkages coupling nanoparticles to the cell surface

HER1-Targeted 86Y-Panitumumab Possesses Superior Targeting Characteristics than 86Y-Cetuximab for PET Imaging of Human Malignant Mesothelioma Tumors Xenografts

Malignant mesothelioma (MM), a rare form of cancer is often associated with previous exposure to fibrous minerals, such as asbestos. Asbestos exposure increases HER1-activity and expression in pre-clinical models. Additionally, HER1 over-expression is observed in the majority of MM cases. In this study, the utility of HER1-targeted chimeric IgG(1), cetuximab, and a human IgG(2), panitumumab, radiolabeled with (86)Y, were evaluated for PET imaging to detect MM non-invasively in vivo, and to select an antibody candidate for radioimmunotherapy (RIT).Radioimmunoconjugates (RICs) of cetuximab and panitumumab were prepared by conjugation with CHX-A''-DTPA followed by radiolabeling with (86)Y. The HER1 expression of NCI-H226, NCI-H2052, NCI-H2452 and MSTO-211H human mesothelioma cells was characterized by flow cytometry. In vivo biodistribution, pharmacokinetic analysis, and PET imaging were performed in tumor bearing athymic mice.In vivo studies demonstrated high HER1 tumor uptake of both RICs. Significant reduction in tumor uptake was observed in mice co-injected with excess mAb (0.1 mg), demonstrating that uptake in the tumor was receptor specific. Significant differences were observed in the in vivo characteristics of the RICs. The blood clearance T(½)α of (86)Y-cetuximab (0.9-1.1 h) was faster than (86)Y-panitumumab (2.6-3.1 h). Also, the tumor area under the curve (AUC) to liver AUC ratios of (86)Y-panitumumab were 1.5 to 2.5 times greater than (86)Y-cetuximab as observed by the differences in PET tumor to background ratios, which could be critical when imaging orthotopic tumors and concerns regarding radiation doses to normal organs such as the liver.This study demonstrates the more favorable HER1-targeting characteristics of (86)Y-panitumumab than (86)Y-cetuximab for non-invasive assessment of the HER1 status of MM by PET imaging. Due to lower liver uptake, panitumumab based immunoconjugates may fare better in therapy than corresponding cetuximab based immunoconjugates

FOXM1 Induces a Global Methylation Signature That Mimics the Cancer Epigenome in Head and Neck Squamous Cell Carcinoma

The oncogene FOXM1 has been implicated in all major types of human cancer. We recently showed that aberrant FOXM1 expression causes stem cell compartment expansion resulting in the initiation of hyperplasia. We have previously shown that FOXM1 regulates HELLS, a SNF2/helicase involved in DNA methylation, implicating FOXM1 in epigenetic regulation. Here, we have demonstrated using primary normal human oral keratinocytes (NOK) that upregulation of FOXM1 suppressed the tumour suppressor gene p16INK4A (CDKN2A) through promoter hypermethylation. Knockdown of HELLS using siRNA re-activated the mRNA expression of p16INK4A and concomitant downregulation of two DNA methyltransferases DNMT1 and DNMT3B. The dose-dependent upregulation of endogenous FOXM1 (isoform B) expression during tumour progression across a panel of normal primary NOK strains (n = 8), dysplasias (n = 5) and head and neck squamous cell carcinoma (HNSCC) cell lines (n = 11) correlated positively with endogenous expressions of HELLS, BMI1, DNMT1 and DNMT3B and negatively with p16INK4A and involucrin. Bisulfite modification and methylation-specific promoter analysis using absolute quantitative PCR (MS-qPCR) showed that upregulation of FOXM1 significantly induced p16INK4A promoter hypermethylation (10-fold, P<0.05) in primary NOK cells. Using a non-bias genome-wide promoter methylation microarray profiling method, we revealed that aberrant FOXM1 expression in primary NOK induced a global hypomethylation pattern similar to that found in an HNSCC (SCC15) cell line. Following validation experiments using absolute qPCR, we have identified a set of differentially methylated genes, found to be inversely correlated with in vivo mRNA expression levels of clinical HNSCC tumour biopsy samples. This study provided the first evidence, using primary normal human cells and tumour tissues, that aberrant upregulation of FOXM1 orchestrated a DNA methylation signature that mimics the cancer methylome landscape, from which we have identified a unique FOXM1-induced epigenetic signature which may have clinical translational potentials as biomarkers for early cancer screening, diagnostic and/or therapeutic interventions

Chemokine Function in Periodontal Disease and Oral Cavity Cancer

The chemotactic cytokines, or chemokines, comprise a superfamily of polypeptides with a wide range of activities that include recruitment of immune cells to sites of infection and inflammation, as well as stimulation of cell proliferation. As such, they function as antimicrobial molecules and play a central role in host defenses against pathogen challenge. However, their ability to recruit leukocytes and potentiate or prolong the inflammatory response may have profound implications for the progression of oral diseases such as chronic periodontitis, where tissue destruction may be widespread. Moreover, it is increasingly recognized that chronic inflammation is a key component of tumor progression. Interaction between cancer cells and their microenvironment is mediated in large part by secreted factors such as chemokines, and serves to enhance the malignant phenotype in oral and other cancers. In this article, we will outline the biological and biochemical mechanisms of chemokine action in host-microbiome interactions in periodontal disease and in oral cancer, and how these may overlap and contribute to pathogenesis

PEGylated Polyamidoamine Dendrimers with Bis-Aryl Hydrazone Linkages for Enhanced Gene Delivery

Surface modification of polyamidoamine (PAMAM) dendrimers with polyethylene glycol (PEG) often results in the decrease in their buffering capacity, which is essential for gene transfer. In this work, bis-aryl hydrazone bond, which possesses protonatable pyridine and amines, was explored as a new linkage for PEGylation of PAMAM dendrimers. PEGylated polyamidoamine (PAMAM) dendrimer G4.0 conjugates with bis-aryl hydrazone (BAH) linkages were synthesized following a two-step procedure: activation of PAMAM dendrimer G4.0 and monofunctional methoxypolyethylene glycol amine (MW=5000 Da) with succinimidyl 4-hydrazinonicotinate acetone hydrazone (SANH) and succinimidyl 4-formylbenzoate (SFB), respectively, and coupling of SFB-activated PEG to SANH-activated G4.0 to generate PEGylated G4.0 with bis-aryl hydrazone linkages (G4.0-BAH-PEG). It was found that the incorporation of BAH linkages into the vector significantly enhanced the buffering capacity of the vector even with a high degree of PEGylation (42 PEG chains per dendrimer). G4.0-BAH-PEG conjugates could complex with DNA plasmid tightly at low weight ratios and display dramatically improved cytocompatibility. According to gene transfection studies in 293T and HN12 cells, this new vector has been shown to be capable of both transfecting more cells and inducing higher gene expression than the parent dendrimer. This work demonstrates that the use of the BAH linkage in coupling of PEG to the dendrimer helps maintain or increase the buffering capacity of the functionalized dendrimer and results in enhanced transfection

Folic Acid-Decorated Polyamidoamine Dendrimer Exhibits High Tumor Uptake and Sustained Highly Localized Retention in Solid Tumors: its Utility for Local SiRNA Delivery

The utility of folic acid (FA)-decorated polyamidoamine dendrimer G4 (G4-FA) as a vector was investigated for local delivery of siRNA. In a xenograft HN12 (or HN12-YFP) tumor mouse model of head and neck squamous cell carcinomas (HNSCC), intratumorally (i.t.) injected G4-FA exhibited high tumor uptake and sustained highly localized retention in the tumors according to near infrared (NIR) imaging assessment. siRNA against vascular endothelial growth factor A (siVEGFA) was chosen as a therapeutic modality. Compared to the nontherapeutic treatment groups (PBS solution or dendrimer complexed with nontherapeutic siRNA against green fluorescent protein (siGFP)), G4-FA/siVEGFA showed tumor inhibition effects in single-dose and two-dose regimen studies. In particular, two doses of G4-FA/siVEGFA i.t. administered eight days apart resulted in a more profound inhibition of tumor growth, accompanied with significant reduction in angiogenesis, as judged by CD31 staining and microvessel counts. Tumor size reduction in the two-dose regimen study was ascertained semi-quantitatively by live fluorescence imaging of YFP tumors and independently supported antitumor effects of G4-FA/siVEGFA. Taken together, G4-FA shows high tumor uptake and sustained retention properties, making it a suitable platform for local delivery of siRNAs to treat cancers that are readily accessible such as HNSCC. Statement of Significance Head and neck squamous cell carcinoma (HNSCC) is the sixth most common cancer worldwide and is difficult to transfect for gene therapy. We developed folate receptor (FR)-targeted polyamidoamine (PAMAM) dendrimer for enhanced delivery of genes to HNSCC and gained in-depth understanding of how gene delivery and transfection in head and neck squamous cancer cells can be enhanced via FR-targeted PAMAM dendrimers. The results we report here are encouraging and present latest advances in using dendrimers for cancer therapies, in particular for HNSCC. Our work has demonstrated that localized delivery of FR-targeted PAMAM dendrimer G4 complexed with siVEGFA resulted in pronounced tumor suppression in an HN12 xenograft tumor model. Tumor suppression was attributed to enhanced tumor uptake of siRNA and prolonged nanoparticle retention in the tumor. Taken together, G4-FA shows high tumor uptake and sustained highly localized retention properties, making it a suitable platform for local delivery of siRNAs to treat cancers that are readily accessible such as HNSCC

Dendrimer-Based RNA Interference Delivery for Cancer Therapy

RNA interference (RNAi) has emerged as a promising tool for cancer treatment. A strenuous ongoing effort for translation of RNAi into clinically acceptable therapy is the development of vectors for efficient and targeted RNAi delivery. In this chapter, we review RNAi-based cancer treatment and the utility of dendrimers in RNAi delivery