Joseph Curry

Cancer metabolism, stemness and tumor recurrence: MCT1 and MCT4 are functional biomarkers of metabolic symbiosis in head and neck cancer

Here, we interrogated head and neck cancer (HNSCC) specimens (n = 12) to examine if different metabolic compartments (oxidative vs. glycolytic) co-exist in human tumors. A large panel of well-established biomarkers was employed to determine the metabolic state of proliferative cancer cells. Interestingly, cell proliferation in cancer cells, as marked by Ki-67 immunostaining, was strictly correlated with oxidative mitochondrial metabolism (OXPHOS) and the uptake of mitochondrial fuels, as detected via MCT1 expression (p < 0.001). More specifically, three metabolic tumor compartments were delineated: (1) proliferative and mitochondrial-rich cancer cells (Ki-67+/TOMM20+/COX+/MCT1+); (2) non-proliferative and mitochondrial-poor cancer cells (Ki-67−/TOMM20−/COX−/MCT1−); and (3) non-proliferative and mitochondrial-poor stromal cells (Ki-67−/TOMM20−/COX−/MCT1−). In addition, high oxidative stress (MCT4+) was very specific for cancer tissues. Thus, we next evaluated the prognostic value of MCT4 in a second independent patient cohort (n = 40). Most importantly, oxidative stress (MCT4+) in non-proliferating epithelial cancer cells predicted poor clinical outcome (tumor recurrence; p < 0.0001; log-rank test), and was functionally associated with FDG-PET avidity (p < 0.04). Similarly, oxidative stress (MCT4+) in tumor stromal cells was specifically associated with higher tumor stage (p < 0.03), and was a highly specific marker for cancer-associated fibroblasts (p < 0.001). We propose that oxidative stress is a key hallmark of tumor tissues that drives high-energy metabolism in adjacent proliferating mitochondrial-rich cancer cells, via the paracrine transfer of mitochondrial fuels (such as L-lactate and ketone bodies). New antioxidants and MCT4 inhibitors should be developed to metabolically target “three-compartment tumor metabolism” in head and neck cancers. It is remarkable that two “non-proliferating” populations of cells (Ki-67−/MCT4+) within the tumor can actually determine clinical outcome, likely by providing high-energy mitochondrial “fuels” for proliferative cancer cells to burn. Finally, we also show that in normal mucosal tissue, the basal epithelial “stem cell” layer is hyper-proliferative (Ki-67+), mitochondrial-rich (TOMM20+/COX+) and is metabolically programmed to use mitochondrial fuels (MCT1+), such as ketone bodies and L-lactate. Thus, oxidative mitochondrial metabolism (OXPHOS) is a common feature of both (1) normal stem cells and (2) proliferating cancer cells. As such, we should consider metabolically treating cancer patients with mitochondrial inhibitors (such as Metformin), and/or with a combination of MCT1 and MCT4 inhibitors, to target “metabolic symbiosis.”

Oncogenes and inflammation rewire host energy metabolism in the tumor microenvironment: RAS and NFκB target stromal MCT4

Here, we developed a model system to evaluate the metabolic effects of oncogene(s) on the host microenvironment. A matched set of “normal” and oncogenically transformed epithelial cell lines were co-cultured with human fibroblasts, to determine the “bystander” effects of oncogenes on stromal cells. ROS production and glucose uptake were measured by FACS analysis. In addition, expression of a panel of metabolic protein biomarkers (Caveolin-1, MCT1, and MCT4) was analyzed in parallel. Interestingly, oncogene activation in cancer cells was sufficient to induce the metabolic reprogramming of cancer-associated fibroblasts toward glycolysis, via oxidative stress. Evidence for “metabolic symbiosis” between oxidative cancer cells and glycolytic fibroblasts was provided by MCT1/4 immunostaining. As such, oncogenes drive the establishment of a stromal-epithelial “lactate-shuttle”, to fuel the anabolic growth of cancer cells. Similar results were obtained with two divergent oncogenes (RAS and NFκB), indicating that ROS production and inflammation metabolically converge on the tumor stroma, driving glycolysis and upregulation of MCT4. These findings make stromal MCT4 an attractive target for new drug discovery, as MCT4 is a shared endpoint for the metabolic effects of many oncogenic stimuli. Thus, diverse oncogenes stimulate a common metabolic response in the tumor stroma. Conversely, we also show that fibroblasts protect cancer cells against oncogenic stress and senescence by reducing ROS production in tumor cells. Ras-transformed cells were also able to metabolically reprogram normal adjacent epithelia, indicating that cancer cells can use either fibroblasts or epithelial cells as “partners” for metabolic symbiosis. The antioxidant N-acetyl-cysteine (NAC) selectively halted mitochondrial biogenesis in Ras-transformed cells, but not in normal epithelia. NAC also blocked stromal induction of MCT4, indicating that NAC effectively functions as an “MCT4 inhibitor”. Taken together, our data provide new strategies for achieving more effective anticancer therapy. We conclude that oncogenes enable cancer cells to behave as selfish “metabolic parasites”, like foreign organisms (bacteria, fungi, viruses). Thus, we should consider treating cancer like an infectious disease, with new classes of metabolically targeted “antibiotics” to selectively starve cancer cells. Our results provide new support for the “seed and soil” hypothesis, which was first proposed in 1889 by the English surgeon, Stephen Paget.

Superficial Musculoaponeurotic System Elevation and Fat Graft Reconstruction After Superficial Parotidectomy

Objective/Hypothesis: Elevation of the superficial musculoaponeurotic system (SMAS) with or without fat graft interposition during superficial parotidectomy prevents a concave facial deformity and Freys syndrome.

Multimodality Education for Airway Endoscopy Skill Development

Objectives: Airway endoscopy is a difficult skill to master. A unique practicum was designed to help otolaryngology residents develop endoscopy skills. The learning modalities included lectures, an animal laboratory, high-fidelity manikins, virtual bronchoscopy simulation, and standardized patients. This study compares the relative subjective value of these learning modalities for skill development and realism. Methods: Participants used a Likert scale (1 = disagree to 5 = agree) and open responses to anonymously rate the efficacy of 5 learning modalities for teaching airway management, endoscopy skills, and clinical leadership and for providing a realistic experience. Results: The results in 2007 were uniformly positive, with mean scores for every category and modality greater than 4 for developing cognitive, psychomotor, and affective skills; managing normal and abnormal conditions; preventing and managing complications; improving endoscopy skills; understanding team process; and experiencing overall and manual “feel” realism. In 2008, the participants were encouraged to more critically evaluate the course. The ratings demonstrated statistically significant differences between the mean scores for 4 of the 9 evaluation categories in 2007 and all 9 categories in 2008. Conclusions: Specific learning modalities (eg, lecture, animal laboratory, high-fidelity manikin, virtual bronchoscopy, standardized patient) were perceived to have different values for teaching airway management, developing endoscopy skills, teaching clinical leadership, and providing a realistic experience. We propose that these learning modalities can be used in a complementary manner.

Meta-analysis of Surgical Techniques for Preventing Parotidectomy Sequelae

OBJECTIVE To conduct a meta-analysis of the literature on surgical methods for the prevention of Frey syndrome and concave facial deformity after parotidectomy. METHODS A PubMed search through February 2008 identified more than 60 English-language studies involving surgical techniques for prevention of these parameters. Analyzed works included 15 retrospective or prospective controlled studies reporting quantitative data for all included participants for 1 or more of the measured parameters in patients who had undergone parotidectomy. Report quality was assessed by the strength of taxonomy recommendation (SORT) score. Data were directly extracted from reports and dichotomized into positive and negative outcomes. The statistical significance was then calculated. RESULTS The mean SORT score for all studies was 2.34, and the mean SORT score for all the analyzed studies was 1.88. Meta-analysis for multiple techniques to prevent symptomatic Frey syndrome, positive starch-iodine test results, and contour deformity favored intervention with a cumulative odds ratio (OR) of 3.88 (95% confidence interval [CI], 2.81-5.34); OR, 3.66 (95% CI; 2.32-5.77); and OR, 5.25 (95% CI, 3.57-7.72), respectively. CONCLUSION Meta-analysis of operative techniques to prevent symptomatic Frey syndrome, positive starch-iodine test results, and facial asymmetry suggests that such methods are likely to reduce the incidence of these complications after parotidectomy.

Early Adoption of Transoral Robotic Surgical Program Preliminary Outcomes

Objective The objective of this study is to demonstrate the feasibility and safety of establishing a transoral robotic surgical (TORS) program in the post–Food and Drug Administration (FDA) approval setting. Early outcomes are compared with the previously reported results of pioneering centers. Study Design Clinical data from a prospective TORS study. Setting Academic university institution. Subjects and Methods Sixty-one patients treated with 63 TORS procedures. Main outcome measures: intraoperative times, margin status, complications, time to diet, and percutaneous endoscopic gastrostomy (PEG) tube retention rate. The authors also report oncologic outcomes on their first 30 patients. Results The spectrum of subsites included tongue base, tonsil, parapharyngeal space, retromolar trigone, supraglottis, and posterior pharyngeal wall. Surgical console time averaged 79 ± 53 minutes. After re-resection of 4 patients, final negative margin status was 94% (50/53). A subset of 30 patients with squamous cell carcinoma reaching an average of 18 months of follow-up had a local regional control rate of 97% with a disease-free survival rate of 90%. The PEG tube retention rate was 7%. Complications included 2 readmissions with dehydration, 1 aspiration pneumonia, and 2 with minor oropharyngeal bleeding. Ninety-one percent of patients resumed an oral diet by the first postoperative visit. Conclusion The initiation of a TORS program in the post-FDA setting can be achieved in a safe and efficient manner. Early results of pioneering TORS centers are reproducible. Continued investigation of TORS as a treatment option for oropharygneal carcinoma is warranted.

Prognostic Indications of Elevated MCT4 and CD147 across Cancer Types: A Meta-Analysis

Background. Metabolism in the tumor microenvironment can play a critical role in tumorigenesis and tumor aggression. Metabolic coupling may occur between tumor compartments; this phenomenon can be prognostically significant and may be conserved across tumor types. Monocarboxylate transporters (MCTs) play an integral role in cellular metabolism via lactate transport and have been implicated in metabolic synergy in tumors. The transporters MCT1 and MCT4 are regulated via expression of their chaperone, CD147. Methods. We conducted a meta-analysis of existing publications on the relationship between MCT1, MCT4, and CD147 expression and overall survival and disease-free survival in cancer, using hazard ratios derived via multivariate Cox regression analyses. Results. Increased MCT4 expressions in the tumor microenvironment, cancer cells, or stromal cells were all associated with decreased overall survival and decreased disease-free survival (p < 0.001 for all analyses). Increased CD147 expression in cancer cells was associated with decreased overall survival and disease-free survival (p < 0.0001 for both analyses). Few studies were available on MCT1 expression; MCT1 expression was not clearly associated with overall or disease-free survival. Conclusion. MCT4 and CD147 expression correlate with worse prognosis across many cancer types. These results warrant further investigation of these associations.

Ultrasound-guided contrast-enhanced sentinel node biopsy of the head and neck in a porcine model

Objective To test the feasibility of contrast-enhanced ultrasound (CEUS)–guided sentinel lymph node biopsy (SNB) of the head and neck in a porcine model. Study Design and Setting In this prospective, non-randomized study, methylene blue and Sonazoid were injected into the lateral tongue or floor of mouth (FOM) of four swine. Real-time CEUS was used to identify contrast in the lymphatic channels flowing to the sentinel lymph node (SLN). Endoscopic or open SNB was performed. Neck dissection was then performed, and the residual nodal packet was examined for remaining contrast-enhancing or blue dye–stained nodes. Results In all eight procedures, the SLN was visualized with ultrasound and blue dye. Seven procedures identified a single SLN, and one identified two SLNs. Subsequent neck dissections revealed no other nodes containing methylene blue or contrast in the nodal specimen or operative bed. Conclusion/Significance CEUS-guided SNB of the head and neck in swine is feasible, with success comparable to blue dye–guided SNB. This technique may offer several advantages over traditional techniques, and warrants further study.

TP53-inducible Glycolysis and Apoptosis Regulator (TIGAR) Metabolically Reprograms Carcinoma and Stromal Cells in Breast Cancer.

A subgroup of breast cancers has several metabolic compartments. The mechanisms by which metabolic compartmentalization develop in tumors are poorly characterized. TP53 inducible glycolysis and apoptosis regulator (TIGAR) is a bisphosphatase that reduces glycolysis and is highly expressed in carcinoma cells in the majority of human breast cancers. Hence we set out to determine the effects of TIGAR expression on breast carcinoma and fibroblast glycolytic phenotype and tumor growth. The overexpression of this bisphosphatase in carcinoma cells induces expression of enzymes and transporters involved in the catabolism of lactate and glutamine. Carcinoma cells overexpressing TIGAR have higher oxygen consumption rates and ATP levels when exposed to glutamine, lactate, or the combination of glutamine and lactate. Coculture of TIGAR overexpressing carcinoma cells and fibroblasts compared with control cocultures induce more pronounced glycolytic differences between carcinoma and fibroblast cells. Carcinoma cells overexpressing TIGAR have reduced glucose uptake and lactate production. Conversely, fibroblasts in coculture with TIGAR overexpressing carcinoma cells induce HIF (hypoxia-inducible factor) activation with increased glucose uptake, increased 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase-3 (PFKFB3), and lactate dehydrogenase-A expression. We also studied the effect of this enzyme on tumor growth. TIGAR overexpression in carcinoma cells increases tumor growth in vivo with increased proliferation rates. However, a catalytically inactive variant of TIGAR did not induce tumor growth. Therefore, TIGAR expression in breast carcinoma cells promotes metabolic compartmentalization and tumor growth with a mitochondrial metabolic phenotype with lactate and glutamine catabolism. Targeting TIGAR warrants consideration as a potential therapy for breast cancer.

Management of aerodigestive tract foreign bodies: innovative teaching concepts.

Objectives: We discuss a method to provide medical education in bronchoesophagology by using high-fidelity patient simulation manikins. Methods: A sophisticated, life-sized infant manikin with realistic anatomic, physiologic, and hemodynamic responses to interventions was programmed to simulate endobronchial foreign body lodgment by blocking ventilation of one lung and manifesting audible stridor, asymmetric chest wall motion, and decreased oxygen saturation. Results: Otolaryngology residents participated in simulation exercises incorporating the cognitive and technical skills necessary for successful airway endoscopy, including technical proficiency and teamwork, to learn to coordinate endoscopy and ventilation and manage laryngospasm. Rather than relying on instructor description, the participants responded directly to the manikin. This sense of realism stimulated participants to rehearse to improve provider performance and patient safety. Simulation provided an agenda determined by the needs of the learners, exploration without direct risk to patients, immediate feedback, and objective documentation. Conclusions: Rapidly evolving medical simulation technologies support activated, effective adult learning; they will play an increasing role in medical education.