Oncogenic Biogenesis of pri-miR-17∼92 Reveals Hierarchy and Competition among Polycistronic MicroRNAs.

The microRNAs encoded by the miR-17∼92 polycistron are commonly overexpressed in cancer and orchestrate a wide range of oncogenic functions. Here, we identify a mechanism for miR-17∼92 oncogenic function through the disruption of endogenous microRNA (miRNA) processing. We show that, upon oncogenic overexpression of the miR-17∼92 primary transcript (pri-miR-17∼92), the microprocessor complex remains associated with partially processed intermediates that aberrantly accumulate. These intermediates reflect a series of hierarchical and conserved steps in the early processing of the pri-miR-17∼92 transcript. Encumbrance of the microprocessor by miR-17∼92 intermediates leads to the broad but selective downregulation of co-expressed polycistronic miRNAs, including miRNAs derived from tumor-suppressive miR-34b/c and from the Dlk1-Dio3 polycistrons. We propose that the identified steps of polycistronic miR-17∼92 biogenesis contribute to the oncogenic re-wiring of gene regulation networks. Our results reveal previously unappreciated functional paradigms for polycistronic miRNAs in cancer.

Loss of the tumor suppressor LKB1 promotes metabolic reprogramming of cancer cells via HIF-1α.

One of the major metabolic changes associated with cellular transformation is enhanced nutrient utilization, which supports tumor progression by fueling both energy production and providing biosynthetic intermediates for growth. The liver kinase B1 (LKB1) is a serine/threonine kinase and tumor suppressor that couples bioenergetics to cell-growth control through regulation of mammalian target of rapamycin (mTOR) activity; however, the influence of LKB1 on tumor metabolism is not well defined. Here, we show that loss of LKB1 induces a progrowth metabolic program in proliferating cells. Cells lacking LKB1 display increased glucose and glutamine uptake and utilization, which support both cellular ATP levels and increased macromolecular biosynthesis. This LKB1-dependent reprogramming of cell metabolism is dependent on the hypoxia-inducible factor-1α (HIF-1α), which accumulates under normoxia in LKB1-deficient cells and is antagonized by inhibition of mTOR complex I signaling. Silencing HIF-1α reverses the metabolic advantages conferred by reduced LKB1 signaling and impairs the growth and survival of LKB1-deficient tumor cells under low-nutrient conditions. Together, our data implicate the tumor suppressor LKB1 as a central regulator of tumor metabolism and growth control through the regulation of HIF-1α-dependent metabolic reprogramming.

Trends in Medicare Reimbursements for Commonly Performed Laryngeal Procedures from 2000 to 2021.

OBJECTIVE: Numerous studies among different specialties have suggested that inflation-adjusted Medicare reimbursements have steadily declined in the last few decades. The objective of this study is to investigate whether this is true within the field of laryngology. STUDY DESIGN: Retrospective Cross-Sectional Study. SETTING: Centers for Medicare & Medicaid Services (CMS) Physician Fee Schedule. METHODS: 2000-2021 fees for laryngeal surgeries (Current Procedural Terminology [CPT] codes 31530, 31531, 31535, 31536, 31540, 31541, 31545, 31546, 31551-31554, 31560, 31561, 31570), and laryngectomies (CPTs 31360, 31365, 31367, 31368, 31370, 31375, 31380, 31382, 31390, 31395) were gathered. United States consumer price index (CPI) was used to adjust all gathered data for inflation to 2021 US dollars. RESULTS: During the study period, unadjusted reimbursement for non-facility and facility laryngeal surgeries decreased an average of 6.1% and 6.6%, respectively. When adjusting for inflation, non-facility and facility laryngeal surgeries saw an average decrease of 17.8% (p < 0.001) and 28.5% (p < 0.001), respectively. Unadjusted reimbursement for facility laryngectomies saw an average increase of 40.2%, correlating to an inflation-adjusted decline of 8.9% (p < 0.001). Among laryngeal procedures overall, there was an average nominal increase of 17.0%, correlating to a 20.3% inflation-adjusted decline. CONCLUSION: In terms of inflation-adjusted dollars, reimbursements for laryngeal procedures have seen a large decrease in the last two decades. Understanding reimbursement trends is critical for sustainability of otolaryngology practices, and can be used by surgeons, hospital systems, and policymakers to guide future healthcare legislation.

Resumption of Otolaryngology Surgical Practice in the Setting of Regionally Receding COVID-19.

The practice of otolaryngology has been drastically altered as a consequence of the ongoing coronavirus disease 2019 (COVID-19) pandemic. Geographic heterogeneity in COVID-19 burden has meant different regions have experienced the pandemic at different stages. Regional dynamics of COVID-19 incidence has dictated the available resources for the provision of surgical care. As regions navigate their own COVID-19 dynamics, illustrative examples of areas affected early by the COVID-19 pandemic may provide anticipatory guidance. In this commentary, we discuss our experience with performed and canceled surgical procedures across the various otolaryngology specialties at our institution over the course of regionally rising and falling incident COVID-19 cases.

Otolaryngology Match 2020-21: Survey of Prospective Applicants in the Setting of COVID-19.

OBJECTIVES: To capture the perspectives of candidates applying for otolaryngology residency positions in the 2020-21 cycle, in the context of disruption caused by the coronavirus disease 2019 (COVID-19) pandemic. SUBJECTS AND METHODS: Candidates planning to apply to the otolaryngology 2020-21 match were invited to complete a cross-sectional online survey. Distribution was via otomatch.com and word of mouth. Descriptive statistics were performed. RESULTS: Of 85 eligible responses (estimated 18.9% of all applicants), many have had at least one board examination (71.8%) disrupted. A majority (85.9%) believe evaluation of candidates will change due to the pandemic, and 54.1% report they were now less confident in matching. Female applicants (37.6% of respondents) were found to have significantly higher odds of decreased confidence in matching (OR 2.781 [95% CI 1.045-7.4044]; P = .041). Many report a move to virtual interviews would increase the number of applications submitted (45.9%) and the number of interviews attended (77.6%). Some applicants (36.5%) did not believe residency programs would gather sufficient information about their candidacy to make an informed decision, and most (62.4%) did not believe that they would gather sufficient information to inform their own rank list. CONCLUSIONS: We find that candidates believe their candidacy will be assessed differently in light of the COVID-19 pandemic, are largely less confident in successfully matching, and are planning to apply and interview more broadly. These data are relevant to otolaryngology residency leadership to inform clear dialogue and a smooth transition into an unprecedented application cycle.

COVID-19's Impact on the 2020-2021 Resident Match: A Survey of Otolaryngology Program Directors.

OBJECTIVE: To determine the impact coronavirus disease of 2019 (COVID-19) will have on the 2020-2021 otolaryngology (OTO-HNS) resident application cycle. METHODS: A cross-sectional survey targeting OTO-HNS program directors (PD) was created and disseminated via email to PDs on May 28th 2020. Descriptive analyses of the 19-question survey was performed, and free text responses for certain suitable questions were thematically categorized into groups determined to be relevant during analysis. RESULTS: Twenty-nine of 123 solicited PDs (23.6%) completed the survey. Nineteen (65.5%) respondents indicated they would not host away rotations (AR) in 2020, and 9 (31.0%) reported that they would consider away rotators without home programs. Regarding the historical importance of AR, 21 (72.4%) PDs stated they were either "extremely" or "very" important in evaluating candidates. Sixteen (55.2%) PDs stated that virtual interviews would impact their ability to properly gauge candidates and 12 (41.4%) were unsure. Eight PDs (27.6%) stated their evaluation of candidates will likely change, with a shift toward an increased reliance on letters of recommendation, research involvement, and clerkship grades. The large majority of PDs-25 (86.2%)-were not worried that the COVID-19 pandemic would affect the abilities of new interns beginning in 2021. CONCLUSION: Virtual interviews and engagement activities will mostly supplant sub-Is and AR for the 2020-2021 OTO-HNS application cycle. Surveyed PDs largely believe these will be insufficient in providing a comprehensive assessment of candidates, and will similarly limit applicants' ability to gauge residency programs. Criteria utilized to evaluate students is expected to change.

The role of vitamin D in head and neck cancer.

OBJECTIVE: Head and neck squamous cell carcinoma (HNSCC) describes a set of malignancies of the head and neck that continue to inflict considerable morbidity and mortality. Because HNSCC often presents at an advanced stage, patients frequently undergo intensive multi-modal therapy with an intent to cure. Vitamin D is a precursor to the biologically active hormone calcitriol which governs bone and calcium physiology that is obtained from diet and UV-B exposure. Vitamin D is known to have pleiotropic effects on health and disease. In this review, we examine the role of vitamin D in cancer with emphasis on HNSCC and discuss potential avenues for further research that might better elucidate the role of vitamin D in the management of HNSCC. REVIEW METHODS: A review of MEDLINE database indexed literature concerning the role and biology of vitamin D in HNSCC was conducted, with special consideration of recently published work and research involving immunobiology and HNSCC. CONCLUSIONS: The available evidence suggests that vitamin D may play a role in protecting against HNSCC, particularly in persons who smoke, although conflicting and limited data exists. Promising initial work encourages the pursuit of further study. IMPLICATIONS FOR PRACTICE: The significant morbidity and mortality that HNSCC brings warrants continued research in available and safe interventions that improve patient outcomes. With the rise of immunotherapy as an effective modality for treatment, continued research of vitamin D as an adjunct in the treatment of HNSCC is supported.

Clinical characteristics and treatment-associated survival of head and neck Ewing sarcoma.

OBJECTIVES: Ewing sarcoma of the head and neck (ESHN) is a rare malignancy for which limited data exists. Herein we examine anatomic distribution of ESHN, demographic characteristics, and multi-modal therapy as potential determinants in the overall survival (OS) of patients with ESHN. METHODS: A retrospective study of the National Cancer Database (NCDB) from 2004-2016 was performed. A multivariate Cox regression and univariate Kaplan-Meier survival analyses were conducted. RESULTS: We identified 284 patients with ESHN eligible for demographic analysis and 223 for survival analysis. Approximately half (50.3%) of patients with ESHN were under the age of 18. Pediatric patients (<18) were less likely to present with distant metastases (≤8.0% vs. 9.5-19.0%, P = .006) and more likely to present with osseous disease (90.2% vs. 75.2%, P = .001) than adults. Adult age (HR: 2.727, 95% CI, 1.381-5.384, P = .004) and distant metastatic disease at the time of presentation (HR: 8.161, 95% CI, 2.922-22.790, P < .001) were independently associated with worse OS. The addition of local therapy (either surgery, radiotherapy, or both) to chemotherapy was not associated with improved survival when compared to treatment with chemotherapy alone. CONCLUSION: Predictors of OS in patients with ESHN included age < 18 years and non-metastatic disease at the time of diagnosis. Tumor site of origin (osseous vs. extraosseous primary) or the addition of local therapy to chemotherapy had no impact on OS. Our analysis suggests that chemotherapy serves as the primary modality in treating ESHN, while further study of this rare malignancy is required to discern the utility of combined systemic and local therapy. Laryngoscope, 130:2385-2392, 2020.

Repression of LKB1 by miR-17∼92 Sensitizes MYC-Dependent Lymphoma to Biguanide Treatment.

Cancer cells display metabolic plasticity to survive stresses in the tumor microenvironment. Cellular adaptation to energetic stress is coordinated in part by signaling through the liver kinase B1 (LKB1)-AMP-activated protein kinase (AMPK) pathway. Here, we demonstrate that miRNA-mediated silencing of LKB1 confers sensitivity of lymphoma cells to mitochondrial inhibition by biguanides. Using both classic (phenformin) and newly developed (IM156) biguanides, we demonstrate that elevated miR-17∼92 expression in Myc+ lymphoma cells promotes increased apoptosis to biguanide treatment in vitro and in vivo. This effect is driven by the miR-17-dependent silencing of LKB1, which reduces AMPK activation in response to complex I inhibition. Mechanistically, biguanide treatment induces metabolic stress in Myc+ lymphoma cells by inhibiting TCA cycle metabolism and mitochondrial respiration, exposing metabolic vulnerability. Finally, we demonstrate a direct correlation between miR-17∼92 expression and biguanide sensitivity in human cancer cells. Our results identify miR-17∼92 expression as a potential biomarker for biguanide sensitivity in malignancies.

NSD1 mutations by HPV status in head and neck cancer: differences in survival and response to DNA-damaging agents.

BACKGROUND: Compared to HPV-negative head and neck squamous cell carcinomas (HNSCCs), HPV-positive HNSCCs are associated with a favorable prognosis in part due to their improved treatment sensitivity. Inactivating mutations in NSD1 were shown to be a favorable prognostic biomarker in laryngeal cancers. Here, we characterize NSD1 mutations from the expanded The Cancer Genome Atlas (TCGA) HNSCC cohort (n = 522) and examine their prognostic implications based on HPV status of the tumor. We also begin to examine if NSD1 regulates response to platinum-based drugs and other DNA-damaging agents. METHODS: TCGA HNSCC samples were segregated by HPV and NSD1 mutations using cBioPortal and patient survival was determined. Pathogenicity of mutations was predicted using UMD-Predictor. NSD1-depleted cell lines were established by transfection with control or shRNAs against NSD1, followed by puromycin selection, and confirmed by qRT-PCR. Cell sensitivity to DNA damaging agents was assessed using short-term proliferation and long-term clonogenic survival assays. RESULTS: Among 457 HPV(-) tumors, 13% contained alterations in the NSD1 gene. The majority (61.3%) of NSD1 gene alterations in HPV(-) specimens were truncating mutations within or before the enzymatic SET domain. The remaining alterations included homozygous gene deletions (6.7%), missense point mutations (30.7%) and inframe deletions (1.3%). UMD-Predictor categorized 18 of 23 missense point mutations as pathogenic. For HPV(+) HNSCC (n = 65), 6 NSD1 mutations, comprised of two truncating (33%) and 4 missense point (66%) mutations, were identified. Three of the 4 missense point mutations were predicted to be pathogenic or probably pathogenic by UMD-Predictor. Kaplan-Meier survival analysis determined significantly improved survival of HPV(-) HNSCC patients whose tumors harbored NSD1 gene alterations, as compared to patients with wild-type NSD1 tumors. Interestingly, the survival effect of NSD1 mutations observed in HPV-negative HNSCC was reversed in HPV(+) tumors. Proliferation and clonogenic survival of two HPV(-) cell lines stably expressing control or NSD1 shRNAs showed that NSD1-depleted cells were more sensitive to cisplatin and carboplatin, but not to other DNA damaging drugs. CONCLUSIONS: Genetic alterations in NSD1 hold potential as novel prognostic biomarkers in HPV(-) head and neck cancers. NSD1 mutations in HPV(+) cancers may also play a prognostic role, although this effect must be examined in a larger cohort. NSD1 downregulation results in improved sensitivity to cisplatin and carboplatin, but not to other DNA-damaging agents, in epithelial cells. Increased sensitivity to platinum-based chemotherapy agents associated with NSD1 depletion may contribute to improved survival in HPV(-) HNSCCs. Further studies are needed to determine mechanisms through which NSD1 protects HPV(-) HNSCC cells from platinum-based therapy, as well as confirmation of NSD1 effect in HPV(+) HNSCC.

The miR-17∼92 microRNA Cluster Is a Global Regulator of Tumor Metabolism.

A central hallmark of cancer cells is the reprogramming of cellular metabolism to meet the bioenergetic and biosynthetic demands of malignant growth. Here, we report that the miR-17∼92 microRNA (miRNA) cluster is an oncogenic driver of tumor metabolic reprogramming. Loss of miR-17∼92 in Myc(+) tumor cells leads to a global decrease in tumor cell metabolism, affecting both glycolytic and mitochondrial metabolism, whereas increased miR-17∼92 expression is sufficient to drive increased nutrient usage by tumor cells. We mapped the metabolic control element of miR-17∼92 to the miR-17 seed family, which influences cellular metabolism and mammalian target of rapamycin complex 1 (mTORC1) signaling through negative regulation of the LKB1 tumor suppressor. miR-17-dependent tuning of LKB1 levels regulates both the metabolic potential of Myc(+) lymphomas and tumor growth in vivo. Our results establish metabolic reprogramming as a central function of the oncogenic miR-17∼92 miRNA cluster that drives the progression of MYC-dependent tumors.

AMPK is a negative regulator of the Warburg effect and suppresses tumor growth in vivo.

AMPK is a metabolic sensor that helps maintain cellular energy homeostasis. Despite evidence linking AMPK with tumor suppressor functions, the role of AMPK in tumorigenesis and tumor metabolism is unknown. Here we show that AMPK negatively regulates aerobic glycolysis (the Warburg effect) in cancer cells and suppresses tumor growth in vivo. Genetic ablation of the α1 catalytic subunit of AMPK accelerates Myc-induced lymphomagenesis. Inactivation of AMPKα in both transformed and nontransformed cells promotes a metabolic shift to aerobic glycolysis, increased allocation of glucose carbon into lipids, and biomass accumulation. These metabolic effects require normoxic stabilization of the hypoxia-inducible factor-1α (HIF-1α), as silencing HIF-1α reverses the shift to aerobic glycolysis and the biosynthetic and proliferative advantages conferred by reduced AMPKα signaling. Together our findings suggest that AMPK activity opposes tumor development and that its loss fosters tumor progression in part by regulating cellular metabolic pathways that support cell growth and proliferation.