John E. Phay

Targeting RET Receptor Tyrosine Kinase Activation in Cancer

After ligand binding induces dimerization, the RET receptor tyrosine kinase activates multiple signal transduction pathways. Constitutively activating mutations and chromosomal rearrangements are the primary oncogenic event in a significant number of medullary thyroid cancers (MTC) and papillary thyroid cancers (PTC), respectively. When specific germline mutations in RET are identified early, prophylactic thyroidectomy can be timed to remove at-risk tissue in patients with multiple endocrine neoplasia 2 (MEN2) syndromes who would otherwise develop MTC. Conventional therapy for progressive metastatic MTC is limited. Small-molecule tyrosine kinase inhibitors can target multiple kinases at nanomolar concentrations, including RET, and have shown efficacy against a variety of malignancies. Initial clinical evidence suggests that several of these inhibitors, including sorafenib, vandetanib, motesanib, sunitinib, and XL-184, may have some benefit in treating progressive MTC. Although initial success seen in these trials seems to be modest, it represents a major breakthrough in the treatment of patients with widespread metastatic MTC. Clin Cancer Res; 16(24); 5936–41. ©2010 AACR.

Gastrointestinal Manifestations of Multiple Endocrine Neoplasia Type 2

ObjectiveTo determine the clinical features, natural history, and role of surgery for gastrointestinal manifestations of the multiple endocrine neoplasia type 2 (MEN 2) syndromes. Summary Background DataThe MEN 2 syndromes are characterized by medullary thyroid carcinoma and other endocrinopathies. In addition, some patients with MEN 2A develop Hirschsprung’s disease (HD), and all patients with MEN 2B have intestinal neuromas and megacolon that can cause significant gastrointestinal problems. MethodsFrom 83 families with MEN 2A, eight patients with HD were identified (MEN 2A-HD). These and all patients with MEN 2B followed at the authors’ institution (n = 53) were sent questionnaires to describe the onset and type of gastrointestinal symptoms and treatment they had before the diagnosis of MEN 2. Records of all patients responding were reviewed, including radiographic imaging, histology, surgical records, and genetic testing. ResultsThirty-six of the 61 patients (59%) responded (MEN 2A = 8, MEN 2B = 28) to the questionnaires. All patients with MEN 2A-HD were operated on for HD 2 to 63 years before being diagnosed with MEN 2. All patients responding were underweight as infants and had symptoms of abdominal pain, distention, and constipation. Eighty-eight percent had hematochezia, 63% had emesis, and 33% had intermittent diarrhea before surgery. All patients with MEN 2A-HD had rectal biopsies with a diverting colostomy as the initial surgical procedure. This was followed by a colostomy takedown and pull-through procedure at a later interval. Ninety-three percent of patients with MEN 2B had gastrointestinal symptoms 1 to 24 years before the diagnosis of MEN 2. Symptoms included flatulence (86%), abdominal distention or being underweight as a child (64%), abdominal pain (54%), constipation or diarrhea (43%), difficulty swallowing (39%), and vomiting (14%). Seventy-one percent of patients with MEN-2B with gastrointestinal symptoms had radiographic imaging, 32% were admitted to the hospital, and 29% underwent surgery. ConclusionsPatients with MEN 2A-HD had a typical HD presentation and always required surgery. Patients with MEN 2B have significant gastrointestinal symptoms, but less than a third had surgical intervention. Understanding the clinical course and differences in these patients will improve clinical management.

Multiple functional variants in long-range enhancer elements contribute to the risk of SNP rs965513 in thyroid cancer

Significance Papillary thyroid carcinoma (PTC) displays a strong hereditary component that is, in part, due to the additive effects of numerous low-penetrance genes or variants, but virtually no mechanistic information is available. Here, we studied a well-known low-penetrance variant (SNP rs965513) located in a region devoid of coding genes. We show that at least four variants located in the immediate vicinity of rs965513 reside in enhancer elements that bind to the promoter region shared by two adjacent thyroid-related genes, forkhead box E1 (FOXE1) and PTC susceptibility candidate 2 (PTCSC2), regulating their expression. The role of intergenic regulatory variants in cancer predisposition and carcinogenesis is growing. Further mechanistic understanding of how these variants work such as described here needs to be acquired. The [A] allele of SNP rs965513 in 9q22 has been consistently shown to be highly associated with increased papillary thyroid cancer (PTC) risk with an odds ratio of ∼1.8 as determined by genome-wide association studies, yet the molecular mechanisms remain poorly understood. Previously, we noted that the expression of two genes in the region, forkhead box E1 (FOXE1) and PTC susceptibility candidate 2 (PTCSC2), is regulated by rs965513 in unaffected thyroid tissue, but the underlying mechanisms were not elucidated. Here, we fine-mapped the 9q22 region in PTC and controls and detected an ∼33-kb linkage disequilibrium block (containing the lead SNP rs965513) that significantly associates with PTC risk. Chromatin characteristics and regulatory element signatures in this block disclosed at least three regulatory elements functioning as enhancers. These enhancers harbor at least four SNPs (rs7864322, rs12352658, rs7847449, and rs10759944) that serve as functional variants. The variant genotypes are associated with differential enhancer activities and/or transcription factor binding activities. Using the chromosome conformation capture methodology, long-range looping interactions of these elements with the promoter region shared by FOXE1 and PTCSC2 in a human papillary thyroid carcinoma cell line (KTC-1) and unaffected thyroid tissue were found. Our results suggest that multiple variants coinherited with the lead SNP and located in long-range enhancers are involved in the transcriptional regulation of FOXE1 and PTCSC2 expression. These results explain the mechanism by which the risk allele of rs965513 predisposes to thyroid cancer.

Metastatic mechanisms in follicular cell-derived thyroid cancer

Thyroid cancer incidence is rising annually largely related to enhanced detection and early stage well-differentiated primary tumors. The prognosis for patients with early stage thyroid cancer is outstanding with most patients being cured with surgery. In selected cases, I-131 is administered to treat known or suspected residual or metastatic disease. Even patients with loco-regional metastases typically have an outstanding long-term prognosis, albeit with monitoring and occasional intervention for residual or recurrent disease. By contrast, individuals with distant metastases from thyroid cancer, particularly older patients with larger metastatic burdens and those with poorly differentiated tumors, have a poor prognosis. Patients with metastatic anaplastic thyroid cancer have a particularly poor prognosis. Published clinical trials indicate that transient disease control and partial remissions can be achieved with kinase inhibitor therapy directed toward angiogenic targets and that in some cases I-131 uptake can be enhanced. However, the direct targets of activity in metastatic lesions are incompletely defined and clear evidence that these treatments increase the duration or quality of life of patients is lacking, underscoring the need for improved knowledge regarding the metastatic process to inform the development of new therapies. In this review, we will focus on current data and hypotheses regarding key regulators of metastatic dormancy, metastatic progression, and the role of putative cancer stem cells.

A Novel Dual AMPK Activator/mTOR Inhibitor Inhibits Thyroid Cancer Cell Growth

CONTEXT Activated AMP protein kinase (AMPK) is a key regulator of intracellular energy homeostasis and may also function as a tumor suppressor by inhibiting cell growth through suppression of mammalian target of rapamycin (mTOR)/p70S6K signaling. AMPK activating agents, such as metformin and 5-aminoimidazole-4-carboxamide-ribonucleoside, have been demonstrated to inhibit thyroid cancer cell growth in in vitro and in vivo models. OSU-53, a recently developed AMPK activator, was previously shown to exhibit both in vitro and in vivo antitumor activity against aggressive breast cancer cell lines and their xenografts in nude mice. OBJECTIVE The objective of the study was to assess the in vitro effects of OSU-53 treatment in a panel of thyroid cancer cells. DESIGN Experiments were performed to determine the effects of OSU-53 on cell growth, oncogenic signaling, apoptosis, autophagy, and cell rescue after selective knockdown of AMPK. RESULTS OSU-53 inhibited in vitro cell growth of all seven thyroid cancer cells tested and induced activation of AMPK. Cell lines with activating mutations in RAS or BRAF, compared with cells with phosphatase and tensin homolog deleted from chromosome 10 null and RET/papillary thyroid carcinoma mutations, were more sensitive to drug treatment and demonstrated a more robust AMPK activation, inhibition of mTOR signaling, and autophagy stimulation. After selective knockdown of AMPK, cell rescue from OSU-53 treatment was not observed. We demonstrated an off-target effect of direct mTOR inhibition by OSU-53. Increased autophagy was observed in cells with activation RAS or BRAF mutations. CONCLUSIONS OSU-53, a novel dual-AMPK activator/mTOR inhibitor, effectively inhibits growth in a variety of thyroid cancer cell lines and is most potent in cells with activating mutations in RAS or BRAF.

Label-free Intraoperative Parathyroid Localization With Near-Infrared Autofluorescence Imaging

CONTEXT The inability to accurately localize the parathyroid glands during parathyroidectomy and thyroidectomy procedures can prevent patients from achieving postoperative normocalcemia. There is a critical need for an improved intraoperative method for real-time parathyroid identification. OBJECTIVE The objective of the study was to test the accuracy of a real-time, label-free technique that uses near-infrared (NIR) autofluorescence imaging to localize the parathyroid. SETTING The study was conducted at the Vanderbilt University endocrine surgery center. SUBJECTS AND METHODS Patients undergoing parathyroidectomy and/or thyroidectomy were included in this study. To validate the intrinsic fluorescence signal in parathyroid, point measurements from 110 patients were collected using NIR fluorescence spectroscopy. Fluorescence imaging was performed on 6 patients. Imaging contrast is based on a previously unreported intrinsic NIR fluorophore in the parathyroid gland. The accuracy of fluorescence imaging was analyzed in comparison with visual assessment and histological findings. MAIN OUTCOME MEASURE The detection rate of parathyroid glands was measured. RESULTS The parathyroid glands in 100% of patients measured with fluorescence imaging were successfully detected in real time. Fluorescence images consistently showed 2.4 to 8.5 times higher emission intensity from the parathyroid than surrounding tissue. Histological validation confirmed that the high intrinsic fluorescence signal in the parathyroid gland can be used to localize the parathyroid gland regardless of disease state. CONCLUSION NIR fluorescence imaging represents a highly sensitive, real-time, label-free tool for parathyroid localization during surgery. The elegance and effectiveness of NIR autofluorescence imaging of the parathyroid gland makes it highly attractive for clinical application in endocrine surgery.

Curative surgical resection of adrenocortical carcinoma: Determining long-term outcome based on conditional disease-free probability

Objective: To evaluate conditional disease-free survival (CDFS) for patients who underwent curative intent surgery for adrenocortical carcinoma (ACC). Background: ACC is a rare but aggressive tumor. Survival estimates are usually reported as survival from the time of surgery. CDFS estimates may be more clinically relevant by accounting for the changing likelihood of disease-free survival (DFS) according to time elapsed after surgery. Methods: CDFS was assessed using a multi-institutional cohort of patients. Cox proportional hazards models were used to evaluate factors associated with DFS. Three-year CDFS (CDFS3) estimates at “x” year after surgery were calculated as follows: CDFS3 = DFS(x+3)/DFS(x). Results: One hundred ninety-two patients were included in the study cohort; median patient age was 52 years. On presentation, 36% of patients had a functional tumor and median size was 11.5 cm. Most patients underwent R0 resection (75%) and 9% had N1 disease. Overall 1-, 3-, and 5-year DFS was 59%, 34%, and 22%, respectively. Using CDFS estimates, the probability of remaining disease free for an additional 3 years given that the patient had survived without disease at 1, 3, and 5 years, was 43%, 53%, and 70%, respectively. Patients with less favorable prognosis at baseline demonstrated the greatest increase in CDFS3 over time (eg, capsular invasion: 28%–88%, &Dgr;60% vs no capsular invasion: 51%–87%, &Dgr;36%). Conclusions: DFS estimates for patients with ACC improved dramatically over time, in particular among patients with initial worse prognoses. CDFS estimates may provide more clinically relevant information about the changing likelihood of DFS over time.

MYH9 binds to lncRNA gene PTCSC2 and regulates FOXE1 in the 9q22 thyroid cancer risk locus.

Significance Papillary thyroid carcinoma (PTC) is the most common endocrine cancer and displays strong heritability. So far, the most significant known predisposing variant is rs965513 in 9q22. Although a long noncoding RNA, papillary thyroid cancer susceptibility candidate 2 (PTCSC2), has been characterized in this locus, its mode of action in the carcinogenetic process is unknown. Here, we identify myosin-9 (MYH9) as a binding protein of PTCSC2 that regulates the bidirectional promoter shared by PTCSC2 and forkhead box E1 (FOXE1). PTCSC2 can rescue the promoter inhibition caused by MYH9. The p53 pathway is profoundly affected by the inhibition of FOXE1. Our study discovers fundamental roles for PTCSC2, MYH9, and FOXE1 in thyroid cancer and provides a description of the regulatory mechanism. A locus on chromosome 9q22 harbors a SNP (rs965513) firmly associated with risk of papillary thyroid carcinoma (PTC). The locus also comprises the forkhead box E1 (FOXE1) gene, which is implicated in thyroid development, and a long noncoding RNA (lncRNA) gene, papillary thyroid cancer susceptibility candidate 2 (PTCSC2). How these might interact is not known. Here we report that PTCSC2 binds myosin-9 (MYH9). In a bidirectional promoter shared by FOXE1 and PTCSC2, MYH9 inhibits the promoter activity in both directions. This inhibition can be reversed by PTCSC2, which acts as a suppressor. RNA knockdown of FOXE1 in primary thyroid cells profoundly interferes with the p53 pathway. We propose that the interaction between the lncRNA, its binding protein MYH9, and the coding gene FOXE1 underlies the predisposition to PTC triggered by rs965513.

Actual 10-year survivors following resection of adrenocortical carcinoma

Adrenocortical carcinoma (ACC) is a rare and aggressive malignancy with limited therapeutic options beyond surgical resection. The characteristics of actual long‐term survivors following surgical resection for ACC have not been previously reported.

Nomograms to Predict Recurrence-Free and Overall Survival After Curative Resection of Adrenocortical Carcinoma

IMPORTANCE Adrenocortical carcinoma (ACC) is a rare but aggressive endocrine tumor, and the prognostic factors associated with long-term outcomes after surgical resection remain poorly defined. OBJECTIVES To define clinicopathological variables associated with recurrence-free survival (RFS) and overall survival (OS) after curative surgical resection of ACC and to propose nomograms for individual risk prediction. DESIGN, SETTING, AND PARTICIPANTS Nomograms to predict RFS and OS after surgical resection of ACC were proposed using a multi-institutional cohort of patients who underwent curative-intent surgery for ACC at 13 major institutions in the United States between March 17, 1994, and December 22, 2014. The dates of our study analysis were April 15, 2015, to May 12, 2015. MAIN OUTCOMES AND MEASURES The discriminative ability and calibration of the nomograms to predict RFS and OS were tested using C statistics, calibration plots, and Kaplan-Meier curves. RESULTS In total, 148 patients who underwent surgery for ACC were included in the study. The median patient age was 53 years, and 65.5% (97 of 148) of the patients were female. One-third of the patients (35.1% [52 of 148]) had a functional tumor, and the median tumor size was 11.2 cm. Most patients (77.7% [115 of 148]) underwent R0 resection, and 8.8% (13 of 148) of the patients had N1 disease. Using backward stepwise selection of clinically important variables with the Akaike information criterion, the following variables were incorporated in the prediction of RFS: tumor size of at least 12 cm (hazard ratio [HR], 3.00; 95% CI, 1.63-5.70; P < .001), positive nodal status (HR, 4.78; 95% CI, 1.47-15.50; P = .01), stage III/IV (HR, 1.80; 95% CI, 0.95-3.39; P = .07), cortisol-secreting tumor (HR, 2.38; 95% CI, 1.27-4.48; P = .01), and capsular invasion (HR, 1.96; 95% CI, 1.02-3.74; P = .04). Factors selected as predicting OS were tumor size of at least 12 cm (HR, 1.78; 95% CI, 1.00-3.17; P = .05), positive nodal status (HR, 5.89; 95% CI, 2.05-16.87; P = .001), and R1 margin (HR, 2.83; 95% CI, 1.51-5.30; P = .001). The discriminative ability and calibration of the nomograms revealed good predictive ability as indicated by the C statistics (0.74 for RFS and 0.70 for OS). CONCLUSIONS AND RELEVANCE Independent predictors of survival and recurrence risk after curative-intent surgery for ACC were selected to create nomograms predicting RFS and OS. The nomograms were able to stratify patients into prognostic groups and performed well on internal validation.