Faculty Bibliography

Head and neck cancer (HNC) is the seventh most common cancer worldwide, the majority being oral squamous cell carcinoma. Despite advances in cancer diagnosis and treatment, the survival rate of patients with HNC remains stagnant. The cancer-nerve interaction has been recognized as an important driver of cancer progression. Schwann cells, a type of peripheral glia, have been implicated in promoting cancer cell growth, migration, dispersion, and invasion into the nerve in many cancers. Here, it is demonstrated that the presence of Schwann cells makes oral cancer cells more aggressive by promoting their proliferation, extracellular matrix breakdown, and altering cell metabolism. Furthermore, oral cancer cells became larger, more circular, with more projections and nuclei following co-culturing with Schwann cells. RNA-sequencing analysis in oral cancer cells following exposure to Schwann cells shows corresponding changes in genes involved in the hallmarks of cancer and cell metabolism; the enriched KEGG pathways are spliceosome, RNA transport, cell cycle, axon guidance, signaling pathways regulating pluripotency of stem cells, cAMP signaling, WNT signaling, proteoglycans in cancer and PI3K-Akt signaling. Taken together, these results suggest a significant role for Schwann cells in facilitating oral cancer progression, highlighting their potential as a target to treat oral cancer progression.

Nerves and immunologic mediators play pivotal roles in body homeostasis by interacting with each other through diverse mechanisms. The spread of nerves in the tumor microenvironment increases tumor cell proliferation and disease progression, and this correlates with poor patient outcomes. The effects of sympathetic and parasympathetic nerves on cancer regulation are being investigated. Recent findings demonstrate the possibility of developing therapeutic strategies that target the tumor microenvironment and its components such as immune cells, neurotransmitters, and extracellular vesicles. Therefore, examining and understanding the mechanisms and pathways associated with the sympathetic and parasympathetic nervous systems, neurotransmitters, cancer-derived mediators and their interactions with the immune system in the tumor microenvironment may lead to the development of new cancer treatments. This review discusses the effects of nerve cells, immune cells, and cancer cells have on each other that regulate neurogenesis, cancer progression, and dissemination.

Head and neck cancer (HNC) affects over 890,000 people annually worldwide and has a mortality rate of 50%. Aside from poor survival, HNC pain impairs eating, drinking, and talking in patients, severely reducing quality of life. Different pain phenotype in patients (allodynia, hyperalgesia, and spontaneous pain) results from a combination of anatomical, histopathological, and molecular differences between cancers. Poor pathologic features (e.g., perineural invasion, lymph node metastasis) are associated with increased pain. The use of syngeneic/immunocompetent animal models, as well as a new mouse model of perineural invasion, provides novel insights into the pathobiology of HNC pain. Glial and immune modulation of the tumor microenvironment affect not only cancer progression but also pain signaling. For example, Schwann cells promote cancer cell proliferation, migration, and secretion of nociceptive mediators, whereas neutrophils are implicated in sex differences in pain in animal models of HNC. Emerging evidence supports the existence of a functional loop of cross-activation between the tumor microenvironment and peripheral nerves, mediated by a molecular exchange of bioactive contents (pronociceptive and protumorigenic) via paracrine and autocrine signaling. Brain-derived neurotrophic factor, tumor necrosis factor α, legumain, cathepsin S, and A disintegrin and metalloprotease 17 expressed in the HNC microenvironment have recently been shown to promote HNC pain, further highlighting the importance of proinflammatory cytokines, neurotrophic factors, and proteases in mediating HNC-associated pain. Pronociceptive mediators, together with nerve injury, cause nociceptor hypersensitivity. Oncogenic, pronociceptive mediators packaged in cancer cell-derived exosomes also induce nociception in mice. In addition to increased production of pronociceptive mediators, HNC is accompanied by a dampened endogenous antinociception system (e.g., downregulation of resolvins and µ-opioid receptor expression). Resolvin treatment or gene delivery of µ-opioid receptors provides pain relief in preclinical HNC models. Collectively, recent studies suggest that pain and HNC progression share converging mechanisms that can be targeted for cancer treatment and pain management.

INTRODUCTION/BACKGROUND:Diabetes mellitus (DM) is a complex multisystemic disorder that affects an estimated 21 million Americans. No studies have evaluated the association of DM with the prevalence of each pulpal diagnosis. The objective of this study was to compare the prevalence of each pulp diagnosis including symptomatic irreversible pulpitis (SIP), asymptomatic irreversible pulpitis, reversible pulpitis, normal pulp, and pulp necrosis (PN) in DM patients against a nondiabetic control group. METHODS:A retrospective chart review was approved by Rutgers University Institutional Review Board. The prevalence of the diagnoses SIP, asymptomatic irreversible pulpitis, reversible pulpitis, normal pulp, and PN was calculated from AxiUm (Exan software, Las Vegas, NV) electronic health records at Rutgers School of Dental Medicine. The chi-square test was used to see the relationship between the 2 categoric variables. Second, binary logistic regression analyses were performed for each group. RESULTS:A total of 2979 teeth were diagnosed with a pulp condition between April 2013 and November 2018. The total tooth number of DM patients was 682, whereas the tooth number of nondiabetic patients was 2297. In the subgroup of patients younger than 40 years old, SIP was notably more prevalent in DM patients. In addition, the prevalence of PN in elderly DM patients (60-69 years old) was significantly higher than in the control group. CONCLUSIONS:The prevalence of SIP in DM patients was significantly higher compared with the control group (<40 years old), suggesting the possibility that DM could hypersensitize the subgroup of patients younger than 40 years old to pulpitis pain.

Bacteria-associated late infection of the orthopedic devices would further lead to the failure of the implantation. However, present ordinary antimicrobial strategies usually deal with early infection but fail to combat the late infection of the implants due to the burst release of the antibiotics. Thus, to fabricate long-term antimicrobial (early antibacterial, late antibacterial) orthopedic implants is essential to address this issue. Herein, we developed a sophisticated MAO-I2-PCLx coating system incorporating an underlying iodine layer and an upper layer of polycaprolactone (PCL)-controlled coating, which could effectively eradicate the late bacterial infection throughout the implantation. Firstly, micro-arc oxidation was used to form a microarray tubular structure on the surface of the implants, laying the foundation for iodine loading and PCL bonding. Secondly, electrophoresis was applied to load iodine in the tubular structure as an efficient bactericidal agent. Finally, the surface-bonded PCL coating acts as a controller to regulate the release of iodine. The hybrid coatings displayed great stability and control release capacity. Excellent antibacterial ability was validated at 30 days post-implantation via in vitro experiments and in vivo rat osteomyelitis model. Expectedly, it can become a promising bench-to-bedside strategy for current infection challenges in the orthopedic field.
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Orofacial pain is a universal predicament, afflicting millions of individuals worldwide. Research on the molecular mechanisms of orofacial pain has predominately focused on the role of neurons underlying nociception. However, aside from neural mechanisms, non-neuronal cells, such as Schwann cells and satellite ganglion cells in the peripheral nervous system, and microglia and astrocytes in the central nervous system, are important players in both peripheral and central processing of pain in the orofacial region. This review highlights recent molecular and cellular findings of the glia involvement and glia-neuron interactions in four common orofacial pain conditions such as headache, dental pulp injury, temporomandibular joint dysfunction/inflammation, and head and neck cancer. We will discuss the remaining questions and future directions on glial involvement in these four orofacial pain conditions.

Oral cancer is very painful and impairs a patient's ability to eat, talk, and drink. Mediators secreted from oral cancer can excite and sensitize sensory neurons inducing pain. Cancer mediators can also activate Schwann cells, the peripheral glia that regulates neuronal function and repair. The contribution of Schwann cells to oral cancer pain is unclear. We hypothesize that the oral cancer mediator TNFα activates Schwann cells, which further promotes cancer progression and pain. We demonstrate that TNFα is overexpressed in human oral cancer tissues and correlates with increased self-reported pain in patients. Antagonizing TNFα reduces oral cancer proliferation, cytokine production, and nociception in mice with oral cancer. Oral cancer or TNFα alone increases Schwann cell activation (measured by Schwann cell proliferation, migration, and activation markers), which can be inhibited by neutralizing TNFα. Cancer- or TNFα-activated Schwann cells release pro-nociceptive mediators such as TNFα and nerve growth factor (NGF). Activated Schwann cells induce nociceptive behaviors in mice, which is alleviated by blocking TNFα. Our study suggests that TNFα promotes cancer proliferation, progression, and nociception at least partially by activating Schwann cells. Inhibiting TNFα or Schwann cell activation might serve as therapeutic approaches for the treatment of oral cancer and associated pain.

Metastasis reduces survival in oral cancer patients and pain is their greatest complaint. We have shown previously that oral cancer metastasis and pain are controlled by the endothelin axis, which is a pathway comprised of the endothelin A and B receptors (ET_AR and ET_BR). In this study we focus on individual genes of the pathway, demonstrating that the endothelin axis genes are methylated and dysregulated in cancer tissue. Based on these findings in patients, we hypothesize that ET_AR and ET_BR play dichotomous roles in oral carcinogenesis and pain, such that ET_AR activation and silenced ET_BR expression result in increased carcinogenesis and pain. We test a treatment strategy that targets the dichotomous functions of the two receptors by inhibiting ET_AR with macitentan, an ET_AR antagonist approved for treatment of pulmonary hypertension, and re-expressing the ET_BR gene with adenovirus transduction, and determine the treatment effect on cancer invasion (i.e., metastasis), proliferation and pain in vitro and in vivo. We demonstrate that combination treatment of macitentan and ET_BR gene therapy inhibits invasion, but not proliferation, in cell culture and in a mouse model of tongue cancer. Furthermore, the treatment combination produces an antinociceptive effect through inhibition of endothelin-1 mediated neuronal activation, revealing the analgesic potential of macitentan. Our treatment approach targets a pathway shown to be dysregulated in oral cancer patients, using gene therapy and repurposing an available drug to effectively treat both oral cancer metastasis and pain in a preclinical model.

Cancer invading into nerves, termed perineural invasion (PNI), is associated with pain. Here we show that oral cancer patients with PNI report greater spontaneous pain and mechanical allodynia compared with patients without PNI, suggesting unique mechanisms drive PNI-induced pain. We studied the impact of PNI on peripheral nerve physiology and anatomy using a murine sciatic nerve PNI model. Mice with PNI exhibited spontaneous nociception and mechanical allodynia. PNI induced afterdischarge in A high threshold mechanoreceptors (AHTMRs), mechanical sensitization (i.e., decreased mechanical thresholds) in both A and C HTMRs, and mechanical desensitization in low threshold mechanoreceptors (LTMRs). PNI resulted in nerve damage, including axon loss, myelin damage, and axon degeneration. Electrophysiological evidence of nerve injury included decreased conduction velocity, and increased percentage of both mechanically-insensitive and electrically-unexcitable neurons. We conclude that PNI-induced pain is driven by nerve injury and peripheral sensitization in HTMRs.

Cancer cells secrete pro-nociceptive mediators that sensitize adjacent sensory neurons and cause pain. Identification and characterization of these mediators could pinpoint novel targets for cancer pain treatment. In the present study we identified candidate genes in cancer cell lines that encode for secreted or cell surface proteins that may drive nociception. To undertake this work, we utilized an acute cancer pain mouse model, transcriptomic analysis of publicly available human tumor-derived cell line data, and a literature review. Cancer cell line supernatants were assigned a phenotype based on evoked nociceptive behavior in an acute cancer pain mouse model. We compared gene expression data from nociceptive and non-nociceptive cell lines. Our analyses revealed differentially expressed genes (DEGs) and pathways; many of the identified genes were not previously associated with cancer pain signaling. Epidermal growth factor receptor (EGFR) and disintegrin metalloprotease domain 17 (ADAM17) were identified as potential targets among the DEGs. We found that the nociceptive cell lines contained significantly more ADAM17 protein in the cell culture supernatant compared to non-nociceptive cell lines. Cytoplasmic EGFR was present in almost all (>90%) tongue primary afferent neurons in mice. Monoclonal antibody against EGFR, cetuximab, inhibited cell line supernatant-induced nociceptive behavior in an acute oral cancer pain mouse model. We infer from these data that ADAM17-EGFR signaling is involved in cancer mediator-induced nociception. The differentially expressed genes and their secreted protein products may serve as candidate therapeutic targets for oral cancer pain and warrant further evaluation.