PD-L1 and MRN synergy in platinum-based chemoresistance of head and neck squamous cell carcinoma.

BACKGROUND: We have been investigating the molecular mechanisms of cisplatin-induced chemoresistance in head and neck squamous cell carcinoma (HNSCC). Based on our previous findings, the present study investigates how the Mre11, Rad50, and NBS1 (MRN) DNA repair complex interacts at the molecular level with the programmed cell death ligand 1 (PD-L1) in cisplatin-induced chemoresistance. METHODS: Human HNSCC cell lines were used to determine the role played by PD-L1 in cisplatin resistance. Initial experiments investigated PD-L1 expression levels in cells exposed to cisplatin and whether PD-L1 interacts directly with the MRN complex. Finally, in vitro studies and in vivo experiments on BALB/c nu/nu mice were performed to determine whether interference of PD-L1 or NBS1 synthesis modulated cisplatin resistance. RESULTS: Exposure to cisplatin resulted in PD-L1 being upregulated in the chemoresistant but not the chemosensitive cell line. Subsequent co-immunoprecipitation studies demonstrated that PD-L1 associates with NBS1. In addition, we found that the knockdown of either PD-L1 or NBS1 re-sensitised the chemoresistant cell line to cisplatin. Finally, but perhaps most importantly, synergy was observed when both PD-L1 and NBS1 were knocked down making the formerly chemoresistant strain highly cisplatin sensitive. CONCLUSIONS: PD-L1 plays a pivotal role in cisplatin resistance in chemoresistant human HNSCC cell lines.

Tracheostomy Outcomes on Trauma Patients.

Objective: Tracheostomies are performed in trauma patients for multiple purposes. Approaches to the procedure are usually directed by individual expertise and local preferences. Though generally safe, a tracheostomy can cause serious complications. This study aims to identify complications associated with tracheostomies performed at the level I Trauma Center of the Puerto Rico Medical Center (PRMC) to have an advanced foundation to develop and implement guidelines to improve patient outcomes. Study Design: A retrospective cross-sectional study. Setting: Level I Trauma Center of the PRMC. Methods: Medical charts of 113 trauma adult patients that underwent tracheostomy at the PRMC from 2018 to 2020 were reviewed. Data collected included patient demographics, surgical approach, initial tracheostomy tube size (ITTS), intubation period, and flexible laryngoscopic findings. Complications occurring during and after tracheostomy were documented. The unadjusted relationship of the independent variables and outcome measures was assessed using χ 2 and Fisher's test for categorical variables and the Wilcoxon-Mann-Whitney rank-sum test for continuous ones. Results: Abnormal airway findings detected on flexible laryngoscopic examination were reported in 30 patients in the open tracheostomy (OT) group and 43 patients in the percutaneous tracheostomy group (p = 0.007). Peristomal granulation tissue was reported in 10 patients with an ITTS 8, while in only 1 patient with an ITTS 6 (p = 0.026). Conclusion: This study showed several key findings in our cohort. The OT surgical approach was associated with fewer long-term complications when compared to the percutaneous approach. Also, a statistically significant difference in peristomal granulation tissue findings was found between the ITTS, ITTS-6 and ITTS-8, the smaller size being associated with fewer abnormal findings.

Management of life-threatening post-traumatic otorrhagia.

Otorrhagia can be life-threatening, and acute control of the hemorrhage using easily accessible and practical techniques in the otolaryngology field such as Merocel packing and Kerlix gauze pressure dressing is essential to manage this complication.

A novel combined transoral and transcervical surgical approach for recurrent metastatic medullary thyroid cancer to the parapharyngeal space.

Medullary thyroid cancer (MTC) represents less than 1% of all thyroid cancers. Complete surgical resection remains the mainstay of treatment for locoregional disease. Unfortunately, patients with recurrence may present with metastasis to challenging anatomic locations. We describe the first case of a recurrent MTC metastatic to the parapharyngeal space (PPS) that was managed using a combined transoral robotic surgery (TORS) and transcervical (TC) approach. We review the presentation, natural history, diagnosis and management of recurrent MTC, and describe a novel combined TORS-TC surgical approach for the treatment of PPS metastasis. A 66-year-old male with history of MTC treated with total thyroidectomy in 2000 and a liver resection in 2011 for metastatic MTC was referred to our Head and Neck Surgery Clinic in October 2016 due to increased calcitonin and CEA levels. Exam was significant for mild right tonsillar/pharyngeal bulging and induration. Imaging with PET-CT and MRI showed an enlarging ovoid mass centered within the right PPS without the presence of another systemic metastasis. FNA was consistent with MTC. The patient was taken to the operating room for a combined TORS-TC approach. Final pathology was consistent with metastatic MTC. Until recently, PPS tumors have been managed using highly morbid and cosmetically disfiguring open surgical approach. TORS provides a safe and effective alternative.

Lingual thyroid gland: it's time for awareness.

SUMMARY: Lingual thyroid (LT) gland is the most common type of ectopic thyroid tissue, but it is an extremely rare presentation. We present a case of a 41-year-old Hispanic female patient complaining of dysphonia and dysphagia. As part of the evaluation, fiber optic flexible indirect laryngoscopy (FIL) was performed which revealed a mass at the base of the tongue. The morphological examination was highly suspicious for ectopic thyroid tissue and the diagnosis was confirmed with neck ultrasound and thyroid scintigraphy. Although the patient presented subclinical hypothyroidism, levothyroxine therapy was initiated with a favorable response which included resolution of symptoms and mass size reduction. Our case portrays how thyroid hormone replacement therapy (THRT) may lead to a reduction in the size of the ectopic tissue and improvement of symptoms, thus avoiding the need for surgical intervention which could result in profound hypothyroidism severely affecting the patients' quality of life. LEARNING POINTS: Benign LT and malignant LT are indistinguishable clinically and radiographically for which histopathology is recommended. THRT, radioactive iodine 131 (RAI) therapy, and surgical excision are potential management options for LT. THRT may lead to size reduction of the ectopic tissue and resolution of symptoms avoiding surgical intervention.

Application of infrared-based molecular imaging to a mouse model with head and neck cancer.

BACKGROUND: This study investigated whether near infrared (NIR) or visible fluorescent molecular imaging produced a better representation of a mouse model with head and neck squamous cell carcinoma (HNSCC). Additionally, the study explored whether epidermal growth factor receptor (EGFR)-targeted probes could play an important role in the diagnosis of HNSCC. METHODS: An orthotopic mouse model of HNSCC labeled with the NIR fluorophore, infrared fluorescent protein (iRFP), was developed and monitored noninvasively in real time. The tumors were further evaluated using tumor-specific EGFR-targeted probes conjugated with an NIR dye (IRDye800), or a visible fluorescent protein. RESULTS: The iRFP cell line produced better results than cells emitting visible light when studying local, distant, and deep tumors in the mouse model. The EGFR-targeted probe conjugated with IRDye800 accurately detected tumor perimeters. CONCLUSION: This model has great potential as a unique tool in the study of HNSCC tumor development. © 2015 Wiley Periodicals, Inc. Head Neck 38: E1351-E1357, 2016.

A novel chitosan-hydrogel-based nanoparticle delivery system for local inner ear application.

HYPOTHESIS: A chitosan-hydrogel-based nanoparticle (nanohydrogel) delivery system can be used to deliver therapeutic biomaterials across the round window membrane (RWM) into the inner ear in a mouse model. BACKGROUND: Delivering therapies to the inner ear has always been a challenge for the otolaryngologist. Advances in biomedical nanotechnology, increased understanding of the RWM diffusion properties, and discovery of novel therapeutic targets and agents, have all sparked interest in the controlled local delivery of drugs and biomaterials to the inner ear using nanoparticles (NPs). METHODS: Fluorescently-labeled liposomal NPs were constructed and loaded into a chitosan-based hydrogel to form a nanohydrogel, and in vitro studies were performed to evaluate its properties and release kinetics. Furthermore, the nanohydrogel was applied to the RWM of mice, and perilymph and morphologic analysis were performed to assess the NP delivery and distribution within the inner ear. RESULTS: NPs with an average diameter of 160 nm were obtained. In vitro experiments showed that liposomal NPs can persist under physiologic conditions for at least two weeks without significant degradation and that the nanohydrogel can carry and release these NPs in a controlled and sustained manner. In vivo findings demonstrated that the nanohydrogel can deliver intact nanoparticles into the perilymphatic system and reach cellular structures in the scala media of the inner ear of our mouse model. CONCLUSION: Our study suggests that the nanohydrogel system has great potential to deliver therapeutics in a controlled and sustained manner from the middle ear to the inner ear without altering inner ear structures.

Dual disruption of DNA repair and telomere maintenance for the treatment of head and neck cancer.

PURPOSE: Poly(ADP-ribose) polymerases (PARP) and the Mre11, Rad50, and Nbs1 (MRN) complex are key regulators of DNA repair, and have been recently shown to independently regulate telomere length. Sensitivity of cancers to PARPi is largely dependent on the BRCAness of the cells. Unfortunately, the vast majority of cancers are BRCA-proficient. In this study, therefore, we investigated whether a targeted molecular "hit" on the MRN complex, which is upstream of BRCA, can effectively sensitize BRCA-proficient head and neck squamous cell carcinoma (HNSCC) to PARP inhibitor (PARPi). EXPERIMENTAL DESIGN: Human HNSCC cell lines and a mouse model with HNSCC xenografts were used in this study. In vitro and in vivo studies were conducted to evaluate the effects and underlying mechanisms of dual molecular disruption of PARP and the MRN complex, using a pharmacologic inhibitor and a dominant-negative Nbs1 expression vector, respectively. RESULTS: Our findings demonstrate that downregulation of the MRN complex disrupts homologous recombination, and, when combined with PARPi, leads to accumulation of lethal DNA double-strand breaks. Moreover, we show that PARPi and MRN complex disruption induces significantly shortening telomere length. Together, our results demonstrate that dual disruption of these pathways causes significant cell death in BRCA-proficient tumor cells both in vitro and in vivo. CONCLUSION: Our study, for the first time, elucidates a novel mechanism for MRN complex and PARP inhibition beyond DNA repair, demonstrating the feasibility of a dual disruption approach that extends the utility of PARPi to the treatment of BRCA-proficient cancers.

Low-intensity pulsed ultrasound accelerates tooth movement via activation of the BMP-2 signaling pathway.

The present study was designed to determine the underlying mechanism of low-intensity pulsed ultrasound (LIPUS) induced alveolar bone remodeling and the role of BMP-2 expression in a rat orthodontic tooth movement model. Orthodontic appliances were placed between the homonymy upper first molars and the upper central incisors in rats under general anesthesia, followed by daily 20-min LIPUS or sham LIPUS treatment beginning at day 0. Tooth movement distances and molecular changes were evaluated at each observation point. In vitro and in vivo studies were conducted to detect HGF (Hepatocyte growth factor)/Runx2/BMP-2 signaling pathways and receptor activator of NFκB ligand (RANKL) expression by quantitative real time PCR (qRT-PCR), Western blot and immunohistochemistry. At day 3, LIPUS had no effect on the rat orthodontic tooth movement distance and BMP-2-induced alveolar bone remodeling. However, beginning at day 5 and for the following time points, LIPUS significantly increased orthodontic tooth movement distance and BMP-2 signaling pathway and RANKL expression compared with the control group. The qRT-PCR and Western blot data in vitro and in vivo to study BMP-2 expression were consistent with the immunohistochemistry observations. The present study demonstrates that LIPUS promotes alveolar bone remodeling by stimulating the HGF/Runx2/BMP-2 signaling pathway and RANKL expression in a rat orthodontic tooth movement model, and LIPUS increased BMP-2 expression via Runx2 regulation.

A regulated delivery system for inner ear drug application.

OBJECTIVE: We have recently developed a novel inner ear drug delivery system using chitosan glycerophosphate (CGP) hydrogel loaded with drugs commonly used for treatment of inner ear diseases, significantly improving the drugs' sustained delivery. The goal of this study is to evaluate the effectiveness of chitosanase as a "switch off" mechanism for this drug delivery system when side effects and potential ototoxicities appear during treatment. To evaluate this effect, we tested gentamicin (GENT) in the inner ear following CGP delivery with/without regulation. METHODS: Purified chitosanase was obtained and used for regulating the CGP delivery system. In vitro studies were performed to evaluate the effect of the interaction between chitosanase and CGP-hydrogel loaded with GENT or Texas Red-labeled GENT (GTTR). In vivo studies were performed using our mouse model to investigate the regulatory effect of chitosanase application on the delivery of GENT to the inner ear. To assess the potential drug rerouting regulatory effect of chitosanase the GTTR fluorescence intensity was evaluated at the round window niche (RWN) and the Eustachian tube (ET). To further characterize this regulatory effect, GENT concentration in the perilymph of the inner ear was analyzed by chromatographic tandem mass spectrometry (LC-MS/MS), and the uptake in the inner ear cells was measured using fluorescence microscopy following CGP delivery with/without chitosanase application. RESULTS: The chitosanase effectively digested the CGP-hydrogel, quickly releasing GENT and GTTR from the system in vitro. When reacted with GENT alone chitosanase did not produce any reducing sugars and did not affect GENT's antimicrobial activity. In vivo GTTR was effectively rerouted from the RWN to the ET, limiting its uptake in inner ear hair cells. Concurrent with these findings, GENT concentration in the inner ear perilymph was significantly decreased after chitosanase application. CONCLUSION: Our study findings suggest that, for the first time, sustained and controlled inner ear drug delivery can be successfully regulated enhancing its translation potential for clinical application. The use of chitosanase to digest the CGP-hydrogel results in the rerouting of the loaded drug away from the RWN, effectively downregulating its delivery to the inner ear. This important modification to our drug delivery system has the ability to deliver therapy to the inner ear until desired effect is achieved and to stop this process when side effects or treatment-related ototoxicities start to occur, providing a novel and salient approach for safe and effective delivery to the inner ear.