CD133-Dependent Activation of Phosphoinositide 3-Kinase /AKT/Mammalian Target of Rapamycin Signaling in Melanoma Progression and Drug Resistance.

Melanoma frequently harbors genetic alterations in key molecules leading to the aberrant activation of PI3K and its downstream pathways. Although the role of PI3K/AKT/mTOR in melanoma progression and drug resistance is well documented, targeting the PI3K/AKT/mTOR pathway showed less efficiency in clinical trials than might have been expected, since the suppression of the PI3K/mTOR signaling pathway-induced feedback loops is mostly associated with the activation of compensatory pathways such as MAPK/MEK/ERK. Consequently, the development of intrinsic and acquired resistance can occur. As a solid tumor, melanoma is notorious for its heterogeneity. This can be expressed in the form of genetically divergent subpopulations including a small fraction of cancer stem-like cells (CSCs) and non-cancer stem cells (non-CSCs) that make the most of the tumor mass. Like other CSCs, melanoma stem-like cells (MSCs) are characterized by their unique cell surface proteins/stemness markers and aberrant signaling pathways. In addition to its function as a robust marker for stemness properties, CD133 is crucial for the maintenance of stemness properties and drug resistance. Herein, the role of CD133-dependent activation of PI3K/mTOR in the regulation of melanoma progression, drug resistance, and recurrence is reviewed.

Mechanisms of Melanoma Progression and Treatment Resistance: Role of Cancer Stem-like Cells.

Melanoma is the third most common type of skin cancer, characterized by its heterogeneity and propensity to metastasize to distant organs. Melanoma is a heterogeneous tumor, composed of genetically divergent subpopulations, including a small fraction of melanoma-initiating cancer stem-like cells (CSCs) and many non-cancer stem cells (non-CSCs). CSCs are characterized by their unique surface proteins associated with aberrant signaling pathways with a causal or consequential relationship with tumor progression, drug resistance, and recurrence. Melanomas also harbor significant alterations in functional genes (BRAF, CDKN2A, NRAS, TP53, and NF1). Of these, the most common are the BRAF and NRAS oncogenes, with 50% of melanomas demonstrating the BRAF mutation (BRAFV600E). While the successful targeting of BRAFV600E does improve overall survival, the long-term efficacy of available therapeutic options is limited due to adverse side effects and reduced clinical efficacy. Additionally, drug resistance develops rapidly via mechanisms involving fast feedback re-activation of MAPK signaling pathways. This article updates information relevant to the mechanisms of melanoma progression and resistance and particularly the mechanistic role of CSCs in melanoma progression, drug resistance, and recurrence.

Tumor Microenvironment as a Therapeutic Target in Melanoma Treatment.

The role of the tumor microenvironment in tumor growth and therapy has recently attracted more attention in research and drug development. The ability of the microenvironment to trigger tumor maintenance, progression, and resistance is the main cause for treatment failure and tumor relapse. Accumulated evidence indicates that the maintenance and progression of tumor cells is determined by components of the microenvironment, which include stromal cells (endothelial cells, fibroblasts, mesenchymal stem cells, and immune cells), extracellular matrix (ECM), and soluble molecules (chemokines, cytokines, growth factors, and extracellular vesicles). As a solid tumor, melanoma is not only a tumor mass of monolithic tumor cells, but it also contains supporting stroma, ECM, and soluble molecules. Melanoma cells are continuously in interaction with the components of the microenvironment. In the present review, we focus on the role of the tumor microenvironment components in the modulation of tumor progression and treatment resistance as well as the impact of the tumor microenvironment as a therapeutic target in melanoma.

The Effect of Patient Positioning on Intraoperative Neuromonitoring During Thyroid and Parathyroid Surgery.

BACKGROUND: Intraoperative neuromonitoring (IONM) has been accepted as a routine adjunct among surgeons who perform thyroid and parathyroid surgeries. Thyroid and parathyroid surgeries use various patient positioning strategies that have poorly understood effects on IONM. The aim of this study was to compare IONM signals between the transaxillary and transcervical approaches. METHODS: In this retrospective cohort study, we evaluated 463 adult patients who underwent a total of 502 procedures. The procedures performed included total thyroidectomy, right or left hemithyroidectomy, and parathyroidectomy. Vagus nerve and recurrent laryngeal nerve (RLN) latency and amplitude measurements were analyzed intra-operatively. The distances between the vagus nerve and the trachea were measured via ultrasound during transaxillary procedures. RESULTS: Compared to the transcervical approach, the right vagus nerve latency was significantly decreased in the transaxillary approach. Transaxillary surgery was not associated with increased latency or decreased amplitude on IONM. The distance between the vagus nerve and trachea was significantly decreased post-positioning during transaxillary approaches. DISCUSSION: Despite differences in patient positioning, a transaxillary approach was not associated with increased stress on the vagus nerve or RLN, according to IONM data. The decreased right vagus nerve latency associated with a transaxillary approach highlights the importance of considering patient positioning and laterality while interpreting IONM data.

Diagnostic Accuracy of Ultrasound in Predicting Extrathyroidal Extension and Its Relation to Body Mass Index in a North American Population.

Detection of extrathyroidal extension (ETE) in patients with papillary thyroid carcinoma (PTC) influences treatment plan and surgical aggressiveness. Ultrasound (US) is the long-standing preoperative imaging method of choice. Recent literature from Asia suggests US accuracy to be influenced by patient characteristics, such as body mass index (BMI). Here, we examine the effect of BMI on the accuracy of US at a North American tertiary referral center. A total of 204 PTC-confirmed patients were retrospectively read by a radiologist blinded to surgical pathology findings. The radiologist recorded multiple sonographic features, including ETE, loss of echogenic capsule, nodule vascularity, capsular abutment, and bulging of contour. When considering all patients, the ultrasonographic feature with the best overall performance was loss of echogenic capsule (diagnostic odds ratio (DOR) = 4.48, 95% confidence interval (CI) = 1.86-10.78). Sub-group analysis by patient BMI found that area under the curve (AUC) for sonographic features was greater in non-obese BMI patients (0.71 ± 0.06) when compared with obese patients (0.43 ± 0.05; p = 0.001). Overall, US diagnostic performance was significantly better in non-obese (DOR = 3.70, 95%CI = 1.53-8.94) patients when compared to those who were obese (DOR = 1.12, 95%CI = 0.62-2.03; p = 0.03). Loss of the echogenic capsule did not differ between the two cohorts with respect to DOR (p = 0.51), specificity (p = 0.52), or sensitivity (p = 0.09). Our work suggests that the diagnostic value of ETE detection by US is impaired in obese patients. Considering that loss of the echogenic capsule did not differ with respect to diagnostic performance, specificity, nor sensitivity between non-obese and obese patients, it could be considered the most important predictor of US-determined ETE.

Effects of Parathyroidectomy on Normocalcemic Primary Hyperparathyroidism and the Role of Intraoperative PTH Measurement.

BACKGROUND: Normocalcemic primary hyperparathyroidism (NCpHPT) and normohormonal primary hyperparathyroidism (NHpHPT) are recently recognized variants of primary hyperparathyroidism. Current guidelines for the management hyperparathyroidism recognize NCpHPT as one of the areas that are recommended for more research due to limited available data. METHODS: A retrospective review of patients who had parathyroidectomy between 2014 and 2019. We excluded patients with multiple endocrine neoplasia syndromes and secondary and tertiary hyperparathyroidism. Included patients were classified based on the biochemical profile into classic or normocalcemic hyperparathyroidism group. Collected data included demographics, preoperative localizing imaging, intraoperative parathyroid hormone levels, and postoperative cure rates. RESULTS: 261 patients were included: 160 patients in the classic and 101 patients in the normocalcemic group. Patients in the normocalcemic group had significantly more negative sestamibi scans (n = 58 [8.2%] vs 78 [51.3%], P = <.01), smaller parathyroid glands (mean weight 436.0 ± 593.0 vs 742.4 ± 1109.0 mg, P = .02), higher parathyroid hyperplasia rates (n = 51 [50.5%] vs 69 [43.1%]), and significantly higher intraoperative parathyroid hormone at 10 minutes (78.1 ± 194.6 vs 43.9 ± 62.4 1, P = .04). Positive predictive value of both intraoperative parathyroid hormone and cure rate was lower in the normocalcemic group (84.2% vs 95.7%) and (80.5% vs 95%), respectively. CONCLUSION: Normocalcemic hyperparathyroidism is a challenging disease. Surgeons should be aware of the lower cure rate in this group, interpret intraoperative parathyroid hormone with caution, and have a lower threshold for bilateral neck exploration and 4 glands visualization.

Impact of surgery versus medical management on cardiovascular manifestations in Graves disease.

BACKGROUND: Graves disease is well known to have multiple adverse effects on the cardiovascular system. We compared the cardiovascular outcomes after surgical intervention versus medical treatment in patients with Graves disease. METHODS: We performed a retrospective study of all Graves disease patients with a cardiovascular comorbidity who underwent either surgical or medical management (N = 151). Perioperative biochemical and cardiovascular outcomes from the surgical versus the medical groups were analyzed. RESULTS: Of 151 patients, 69 (45.6%) patients underwent total thyroidectomy and 82 (54.3%) patients received medical treatment. Hypertension resolved in 44.7% of the patients from the surgical group vs 18% in the medical group (P = .03). Tachyarrhythmias, including atrial fibrillation and tachycardia, improved in 85.9% of patients in the surgical group vs 66% in the medical group (P = .01). All cardiovascular manifestations examined, hypertension, tachyarrhythmias, and heart failure, improved in 69% of patients in the surgical group and 42.6% of patients in the medical group during the follow-up period (P < .01). CONCLUSION: Surgical treatment offers a significant and rapid clinical improvement of cardiovascular manifestations in Graves disease patients, such as hypertension, tachyarrhythmias, and heart failure. Surgery should be considered and recommended in Graves disease patients with known cardiovascular manifestations.

A Single Surgeon's 10-Year Experience in Remote-Access Thyroid and Parathyroid Surgery.

BACKGROUND: Remote-access thyroid and parathyroid surgery has gained popularity recently due to its benefit of avoiding visible neck scars. Most of these techniques were described and performed in Asia, on patients with different body habitus compared to American patients. We aim to analyze the learning curve in performing these operations in North America. . METHODS: This is a retrospective cohort study of a 10-year experience by a single surgeon at a North American institute. Patients who underwent thyroid or parathyroid procedures by a transaxillary, retroauricular, or transoral endoscopic thyroidectomy vestibular approach (TOETVA) were included. Cumulative sum (CUSUM) was used to analyze learning curves based on intraoperative blood loss and total operative times and learning phases were divided accordingly. RESULTS: Three hundred seventy-two remote-access thyroid and parathyroid procedures were performed during the study period. Total operative time for transaxillary procedures was initially reduced after the 69th procedure and then again after the 134th case. For retroauricular procedures, marked reduction in the operative time was observed after 21 procedures. Most patients (57.02%) were discharged home on the same day during the mastering phase. In the transaxillary procedures, only 1 case of brachial plexus injury occurred prior to the routine use of somatosensory evoked potential (SSEP) monitoring. DISCUSSION: Remote-access thyroid and parathyroid surgeries can be performed safely with minimal complications in a select group of patients. Analysis of the learning curve in performing these operations aids in structuring a safe and effective learning period for endocrine surgeons seeking to venture into this modality of treatment.

Robotic and Laparoscopic Approaches for Adrenal Surgery in Obese Patients.

OBJECTIVE: Minimally invasive adrenalectomy is a challenging procedure in obese patients. Few recent studies have advocated against robot-assisted adrenalectomy, particularly in obese patients. This study aims to compare operative outcomes between the robotic and laparoscopic adrenalectomy, particularly in obese patients. MATERIALS AND METHODS: A retrospective analysis was performed on all consecutive patients undergoing adrenalectomy for benign disease by a single surgeon using either a laparoscopic or robotic approach. Adrenal surgeries for adrenal cancer were excluded. Demographics, operative time, length of hospital stays, estimated blood loss (EBL), and intraoperative and postoperative complications were evaluated. Patients were divided into 2 groups; obese and nonobese. A sub-analysis was performed comparing robotic and laparoscopic approaches in obese and nonobese patients. RESULTS: Out of 120, 55 (45.83%) were obese (body mass index ≥ 30 kg/m2). 14 (25.45%) of the obese patients underwent a laparoscopic approach, and 41 (74.55%) underwent a robotic approach. Operative times were longer in the obese vs. nonobese groups (173.30 ± 72.90 minutes and 148.20 ± 61.68 minutes, P = .04) and were associated with less EBL (53.77 ± 82.48 vs. 101.30 ± 122, P = .01). The robotic approach required a longer operative time when compared to the laparoscopic approach (187 ± 72.42 minutes vs. 126.60 ± 54.55 minutes, P = .0102) in the obese but was associated with less blood loss (29.02 ± 51.05 mL vs. 138.30 ± 112.20 mL, P < .01) and shorter hospital stay (1.73 ± 1.23 days vs. 3.17 ± 1.27 days, P < .001). CONCLUSION: Robot-assisted adrenal surgery is safe in obese patients and appears to be longer; however, it provides improvements in postoperative outcomes, including EBL and shorter hospital stay.

Ultrasound Elastography Predicts Thyroid Nodule Volume Reduction Rate After Percutaneous Ethanol Ablation.

OBJECTIVES: To evaluate the safety and efficacy of percutaneous ethanol ablation (PEA) on indeterminate thyroid nodules (Bethesda III and IV) based on ultrasound (US) elastography by assessing the volume reduction rate (VRR), relative reduction in size, resolution of compressive symptoms, and post-procedural complications. MATERIALS AND METHODS: This is a retrospective cohort study of all thyroid nodules treated with PEA by a single surgeon at a North American tertiary referral center. Study variables included demographics, nodule characteristics, Bethesda classification, US elastography, presence of compressive symptoms, thyroid function, and post-procedural complications. Relative volume reductions and VRR were calculated at 3- and 6-month follow-ups. RESULTS: Thirty-four thyroid nodules were evaluated in 22 patients. All thyroid nodules underwent a fine needle aspiration prior to PEA. After 6 months, 45% of all thyroid nodules exhibited a VRR of ≥50%. A significant VRR was achieved in the soft thyroid nodules at 6 months (42.15% ± 31), compared to the stiff nodules with 30.92% ± 91.53, P < .05. Post-PEA thyroid stimulating hormone levels did not significantly change after the procedure. Compressive symptoms resolved in all 5 patients who reported it. One patient developed transient vocal cord paresis that resolved in 3 months. DISCUSSION: To the best of our knowledge, this is the largest series of PEA for thyroid nodules in North America. Ultrasound elastography is a useful adjunct in predicting the success of PEA for nonmalignant thyroid nodules. Percutaneous ethanol ablation is both a safe and effective alternative to surgery for relief of compressive symptoms in select patients.

Nuclear morphometry in indeterminate thyroid nodules.

BACKGROUND: Up to 30% of thyroid nodules undergoing fine needle aspiration (FNA) yield an indeterminate result. Recent research efforts have suggested that nuclear morphometry and morphology may enhance the diagnostic accuracy of FNA as an objective adjunct. We applied nuclear morphometric analysis on a diverse cohort of patients to evaluate the association between nuclear morphometry and malignancy. METHODS: Forty-five randomly selected patients, who underwent thyroid surgery after an indeterminate FNA result (Bethesda III & IV) between 2012-2015, were reviewed. One hundred representative nuclei per FNA of a thyroid nodule were analyzed using ImageJ. Seven validated morphometric parameters were collected: nuclear area, perimeter, circularity, aspect ratio, roundness, and maximum/minimum Feret's diameter. L/S ratio was subsequently calculated. All 8 nuclear parameters were reported as averages with standard errors of the mean (SEM). A Student's t-test was used to assess the association of nuclear parameters with final surgical pathology. RESULTS: The mean age of all patients was 56.31±15.39 years, with female patients comprising 68.9% of the cohort. Twenty-two patients had malignant thyroid nodules. The mean perimeter of nuclei for the cohort was 18.48±0.45 µm, the mean area was 22.19±0.93 µm, and the mean maximum Feret's diameter was 6.67±0.13 µm. No significant differences in the 8 nuclear parameters were observed between the malignant and non-malignant groups. CONCLUSIONS: In the population examined, our results suggest that nuclear morphometry is not yet a tool of reliable diagnostic value in accessing malignant and non-malignant thyroid nodules. Further investigation is necessary to identify objective parameters that will enhance diagnostic accuracy of indeterminate FNA cytology to minimize the number of diagnostic thyroid surgery.

Efficacy of indocyanine green fluorescence in predicting parathyroid vascularization during thyroid surgery.

BACKGROUND: We examined the value of indocyanine green (ICG) fluorescence angiography in predicting parathyroid vascularization following thyroid and central compartment surgeries. METHODS: Data were prospectively collected on adult patients undergoing thyroid and/or central compartment surgeries. Outcomes were compared in surgeries performed with and without ICG use. ICG scoring was used to quantify the vascularity of parathyroid glands. RESULTS: One hundred eleven patients were included; 43 (38.7%) patients underwent ICG injections. There was no significant difference in mean parathyroid hormone (PTH) changes at the end of surgery (29.24 vs 23.48 pg/mL, P = .38), symptomatic hypocalcemia (7.9% vs 3.9%, P = .37), or length of stay (1.095 ± 0.22 vs 0.912 ± 0.07 days, P = .51) between surgeries performed with and without ICG. The average vascularization score among individuals undergoing ICG angiography was 2.89 out of a maximum of 8 points. CONCLUSION: Low-flow ICG patterns are not associated with postoperative PTH changes or transient hypocalcemia and may lead to unnecessary parathyroid autotransplantation.

Thyroid surgery and obesity: Cohort study of surgical outcomes and local specific complications.

INTRODUCTION: Obesity is associated with numerous complications after elective general surgeries. The aim is to compare surgical outcomes and local specific complications in obese and non-obese patients after thyroid surgery. METHODS: Retrospective study over a 3-year period at a North American academic institution. Outcome measures were operative time, estimated blood loss, hospital length of stay, and local specific complications (hypocalcemia, recurrent laryngeal nerve injury, wound hematoma, wound seroma, and chyle leakage). RESULTS: A total of 469 patients were included (mean [SD] age, 50.11 [15.01] years; mean [SD] BMI, 30.5 [8.3] kg/m2; 207 [44.14%] obese). There was no difference in operative time (125.7 vs. 129.6, p = 0.52), estimated blood loss (16.88 vs. 14.56, p = 0.28), or hospital length of stay (0.95 vs. 0.95, p = 0.96). Overall, there was no difference in the rates of local specific complications between the two groups. CONCLUSIONS: Obesity is not associated with adverse outcomes in patients undergoing thyroid surgery.

MEF2B is a member of the BCL6 gene transcriptional complex and induces its expression in diffuse large B-cell lymphoma of the germinal center B-cell-like type.

Myocyte enhancer-binding factor 2B (MEF2B) has been implicated as a transcriptional regulator for BCL6. However, details about the interaction between MEF2B and BCL6 during expression, as well as the relationship of MEF2B to the expression of other germinal center (GC) markers, have not yet been fully explained. Using germinal center B-cell-like diffuse large B-cell lymphoma (GC-DLBCL) and activated B-cell diffuse large B-cell lymphoma (ABC-DLBCL) cell lines, we analyzed the expression of MEF2B and its associations with BCL6, CD10, and ERK. Furthermore, small interfering RNA (siRNA) was used to study the possible effects of MEF2B knockdown on these proteins and cell growth. Analysis of the BCL6 transcriptional complex was performed using electrophoretic mobility shift assay. The correlation between MEF2B expression and the genetic type of DLBCL was assessed using immunohistochemistry on 111 patient samples, and via in silico analysis of publicly available microarray (Gene Expression Omnibus (GEO)) datasets. Our results indicate that the expression of MEF2B protein is important for the growth of GC-DLBCL cells, as evidenced by MEF2B knockdown inhibition of cell growth and the subsequent suppression of BCL6, CD10, and ERK phosphorylation. Analysis of BCL6 transcription factors in nuclear extracts of MEF2-expressing DLBCL cells showed involvement of MEF2B with AP-2α and BCL6 proteins in the formation of the BCL6 gene transcriptional complex. Indeed, differential expression of MEF2B in the GC-DLBCL is statistically significant compared to the ABC-DLBCL in the GEO datasets, as well as in tissue microarray, as indicated via immunohistochemistry (Visco-Young algorithm). Our findings indicate that MEF2B is an essential component of the BCL6 gene transcriptional complex for the regulation of DLBCL growth via the promotion of BCL6 expression. Beyond its regulatory role in DLBCL growth, MEF2B expression correlated positively with BCL6 and CD10 expression, and was preferentially expressed in the GBC-DLBCL group.

Well-differentiated thyroid cancer and robotic transaxillary surgery at a North American institution.

BACKGROUND: Recent studies from Asia have reported the safety and feasibility of robotic-assisted thyroid surgery. In the United States, several small series and case reports have been published, mostly regarding treatment of benign disease. The aim of our study is to report the safety and feasibility of robotic surgery for well-differentiated thyroid cancer patients at a North American institution. MATERIALS AND METHODS: We performed a retrospective cohort study using a prospectively collected single-center clinical database at Tulane University Medical Center. We included all well-differentiated thyroid cancer patients who underwent robotic-assisted or conventional cervical approach thyroid surgery with or without lymph node dissections at our institution from January 2015 to June 2017. Patient demographics and perioperative data were collected and analyzed. RESULTS: A total of 144 surgeries for thyroid cancer were performed; 35 (24.3%) were robotic-assisted. There were no significant differences in estimated blood loss, operative times, complication rates, specimen sizes, positive microscopic margins, number of lymph nodes removed with associated lymph node dissections, patient follow-up duration, or clinical recurrence rates between the two groups. Overall length of stay was shorter for robotic-assisted surgery, at 0.6 ± 0.9 d, versus 1.1 ± 1.2 d for conventional open surgery (P = 0.009). For robotic-assisted surgery, 19 patients (54.3%) were discharged on the day of procedure, and only one patient was admitted as inpatient to the hospital (2.9%). CONCLUSIONS: Robot-assisted thyroid surgery is a safe, feasible, and oncologically sound approach for a select group of well-differentiated thyroid cancer patients. However, long-term studies are needed.