Molecular biology of thyroid cancer initiation

Wine- and stir-frying processing of Cuscutae Semen enhance its ability to alleviate oxidative stress and apoptosis via the Keap 1-Nrf2/HO-1 and PI3K/AKT pathways in H2O2-challenged KGN human granulosa cell line

BACKGROUND

Cuscutae Semen (CS) has been prescribed in traditional Chinese medicine (TCM) for millennia as an aging inhibitor, an anti-inflammatory agent, a pain reliever, and an aphrodisiac. Its three main forms include crude Cuscutae Semen (CCS), wine-processed CS (WCS), and stir-frying-processed CS (SFCS). Premature ovarian insufficiency (POI) is a globally occurring medical condition. The present work sought a highly efficacious multi-target therapeutic approach against POI with minimal side effects. Finally, it analyzed the relative differences among CCS, WCS and SFCS in terms of their therapeutic efficacy and modes of action against H2O2-challenged KGN human granulosa cell line.

METHODS

In this study, ultrahigh-performance liquid chromatography (UPLC)-Q-ExactiveTM Orbitrap-mass spectrometry (MS), oxidative stress indices, reactive oxygen species (ROS), Mitochondrial membrane potential (MMP), real-time PCR, Western blotting, and molecular docking were used to investigate the protective effect of CCS, WCS and SFCS on KGN cells oxidative stress and apoptosis mechanisms.

RESULTS

The results confirmed that pretreatment with CCS, WCS and SFCS reduced H2O2-induced oxidative damage, accompanied by declining ROS levels and malondialdehyde (MDA) accumulation in the KGN cells. CCS, WCS and SFCS upregulated the expression of antioxidative levels (GSH, GSH/GSSG ratio, SOD, T-AOC),mitochondrial membrane potential (MMP) and the relative mRNA(Nrf2, Keap1, NQO-1, HO-1, SOD-1, CAT). They inhibited apoptosis by upregulating Bcl-2, downregulating Bax, cleaved caspase-9, and cleaved caspase-3, and lowering the Bax/Bcl-2 ratio. They also exerted antioxidant efficacy by partially activating the PI3K/Akt and Keap1-Nrf2/HO-1 signaling pathways.

CONCLUSIONS

The results of the present work demonstrated the inhibitory efficacy of CCS, WCS and SFCS against H2O2-induced oxidative stress and apoptosis in KGN cells and showed that the associated mechanisms included Keap1-Nrf2/HO-1 activation, P-PI3K upregulation, and P-Akt-mediated PI3K-Akt pathway induction.

Synergistic effect of metformin and vemurufenib (PLX4032) as a molecular targeted therapy in anaplastic thyroid cancer: an in vitro study

BACKGROUND

Survival rate of patients affected with anaplastic thyroid carcinoma (ATC) is less than 5% with current treatment. In ATC, BRAF^V600E mutation is the major mutation that results in the transformation of normal cells in to an undifferentiated cancer cells via aberrant molecular signaling mechanisms. Although vemurufenib is a selective oral drug for the BRAF^V600E mutant kinase with a response rate of nearly 50% in metastatic melanoma, our study has showed resistance to this drug in ATC. Hence the rationale of the study is to explore combinational therapeutic effect to improve the efficacy of vemurafenib along with metformin. Metformin, a diabetic drug is an AMPK activator and has recently proved to be involved in preventing or treating several types of cancer.

METHODS AND RESULTS

Using iGEMDock software, a protein-ligand interaction was successful between Metformin and TSHR (receptor present in the thyroid follicular cells). Our study demonstrates that combination of vemurufenib with metformin has synergistic anti-cancer effects which was evaluated through MTT assay (cytotoxicity), colony formation assay (antiproliferation evaluation) and suppressed the progression of ATC cells growth by inducing significant apoptosis, proven by Annexin V-FITC assay (Early Apoptosis Detection). Downregulation of ERK signaling, upregulation of AMPK pathway and precision in epithelial-mesenchymal transition (EMT) pathway which were assessed by RT-PCR and Western blot provide the evidence that the combination of drugs involved in the precision of altered molecular signaling Further our results suggest that Metformin act as a demethylating agent in anaplastic thyroid cancer cells by inducing the expression of NIS and TSHR. Our study for the first time explored cAMP signaling in ATC wherein cAMP signaling is downregulated due to decrease in intracellular cAMP level upon metformin treatment.

CONCLUSION

To conclude, our findings demonstrate novel therapeutic targets and treatment strategies for undifferentiated ATC.

Downregulation of miR‑193a‑3p via targeting cyclin D1 in thyroid cancer

Thyroid cancer (TC) is a frequently occurring malignant tumor with a rising steadily incidence. microRNA (miRNA/miR)‑193a‑3p is an miRNA that is associated with tumors, playing a crucial role in the genesis and progression of various cancers. However, the expression levels of miR‑193a‑3p and its molecular mechanisms in TC remain to be elucidated. The present study aimed to probe the expression of miR‑193a‑3p and its clinical significance in TC, including its underlying molecular mechanisms. Microarray and RNA sequencing data gathered from three major databases, specifically Gene Expression Omnibus (GEO), ArrayExpress and The Cancer Genome Atlas (TCGA) databases, and the relevant data from the literature were used to examine miR‑193a‑3p expression. Meta‑analysis was also conducted to evaluate the association between clinicopathological parameters and miR‑193a‑3p in 510 TC and 59 normal samples from the TCGA database. miRWalk 3.0, and the TCGA and GEO databases were used to predict the candidate target genes of miR‑193a‑3p. Gene Ontology, Kyoto Encyclopedia of Genes and Genomes and protein‑protein interaction network enrichment analyses were conducted by using the predicted candidate target genes to investigate the underlying carcinogenic mechanisms. A dual luciferase assay was performed to validate the targeting regulatory association between the most important hub gene cyclin D1 (CCND1) and miR‑193a‑3p. miR‑193a‑3p expression was considerably downregulated in TC compared with in the non‑cancer controls (P<0.001). The area under the curve of the summary receiver operating characteristic was 0.80. Downregulation of miR‑193a‑3p was also significantly associated with age, sex and metastasis (P=0.020, 0.044 and 0.048, respectively). Bioinformatics analysis indicated that a low miR‑193a‑3p expression may augment CCND1 expression to affect the biological processes of TC. In addition, CCND1, as a straightforward target, was validated through a dual luciferase assay. miR‑193a‑3p and CCND1 may serve as prognostic biomarkers of TC. Finally, miR‑193a‑3p may possess a crucial role in the genesis and progression of TC by altering the CCND1 expression.

β-catenin signaling is required for RAS-driven thyroid cancer through PI3K activation

Mutations in ß-catenin are traditionally described as late events in thyroid cancer progression. However, the functional implications of ß-catenin dysregulation in the context of tumor initiating events remain unclear. The aim of this work was to investigate whether the two main oncogenic drivers in thyroid cancer, RAS and BRAF, could activate the Wnt/ß-catenin pathway. Expression of HRAS^V12 but not BRAF^V600E in thyroid cells induced ß-catenin nuclear localization, increased ß-catenin-dependent transcriptional activity and inhibited GSK3ß. In a panel of human thyroid cancer cell lines representative of the main genetic events in thyroid cancer, ß-catenin activation was highly dependent on PI3K/AKT activity through its phosphorylation at S552, but not on MAPK. Silencing of ß-catenin expression in cell lines led to a dramatic reduction in proliferation due to an induction of senescence, which was concordant with a reduction in tumor size in nude mice. Moreover, ß-catenin silencing suppressed the expression of EMT-related genes and reduced the invasive capacity of the tumor cells. In conclusion, this work demonstrates that RAS-driven tumors induce PI3K/AKT-dependent ß-catenin activation.

Immune response in thyroid cancer: widening the boundaries

The association between thyroid cancer and thyroid inflammation has been repeatedly reported and highly debated in the literature. In fact, both molecular and epidemiological data suggest that these diseases are closely related and this association reinforces that the immune system is important for thyroid cancer progression. Innate immunity is the first line of defensive response. Unlike innate immune responses, adaptive responses are highly specific to the particular antigen that induced them. Both branches of the immune system may interact in antitumor immune response. Major effector cells of the immune system that directly target thyroid cancer cells include dendritic cells, macrophages, polymorphonuclear leukocytes, mast cells, and lymphocytes. A mixture of immune cells may infiltrate thyroid cancer microenvironment and the balance of protumor and antitumor activity of these cells may be associated with prognosis. Herein, we describe some evidences that immune response may be important for thyroid cancer progression and may help us identify more aggressive tumors, sparing the vast majority of patients from costly unnecessary invasive procedures. The future trend in thyroid cancer is an individualized therapy.

Role of the wnt pathway in thyroid cancer

Aberrant activation of Wnt signaling is involved in the development of several epithelial tumors. Wnt signaling includes two major types of pathways: (i) the canonical or Wnt/β-catenin pathway; and (ii) the non-canonical pathways, which do not involve β-catenin stabilization. Among these pathways, the Wnt/β-catenin pathway has received most attention during the past years for its critical role in cancer. A number of publications emphasize the role of the Wnt/β-catenin pathway in thyroid cancer. This pathway plays a crucial role in development and epithelial renewal, and components such as β-catenin and Axin are often mutated in thyroid cancer. Although it is accepted that altered Wnt signaling is a late event in thyroid cell transformation that affects anaplastic thyroid tumors, recent data suggest that it is also altered in papillary thyroid carcinoma (PTC) with RET/PTC mutations. Therefore, the purpose of this review is to summarize the main relevant data of Wnt signaling in thyroid cancer, with special emphasis on the Wnt/β-catenin pathway.

Differentiated thyroid cancer in navarra (Spain): historic cohort results (1987-2003)

Introduction. Navarra has the highest incidence of differentiated thyroid cancer in Spain. The aim of this study was to review its management carried out by the Navarra's multidisciplinary Thyroid Disease Unit, from 1987 to 2003. Material and Methods. 325 patients were studied to find the incidence, prevalence, and prognostic factors. Statistical analysis comprised univariate and multivariate Cox proportional hazards regression models for survival and tumor recurrence. Results. The average annual incidence was 3.6 per 100,000 inhabitants, with a final prevalence of 82.4 per 100,000. Regarding survival and recurrence, statistical significance was observed for stage IV, follicular carcinoma, capsular and prethyroid muscles invasion, and T4 group. Only survival was related to tumour size larger than 40 mm. Only recurrence was related to lymph node metastases and radioiodine dose higher than 100 mCi. Conclusions. Attendance of patients in a functional unit setting has allowed us to classify them into three risk groups.

[Potential risks of the adverse effects of thyrotropin suppression in differentiated thyroid carcinoma]

In patients with differentiated thyroid carcinoma, long-term inhibition of thyrotropin (TSH) secretion through levothyroxine administration is required when there is evidence of persistent or recurrent disease. In these cases, levothyroxine doses should be monitored to achieve the objectives of inhibiting TSH and avoiding clinical hyperthyroidism. The possibility that suppressive therapy may produce deleterious effects is still controversial, mainly in elderly patients. There are many studies on the potential harmful effects of suppressive therapy on various organs and systems with discrepant results. However, there is no scientific evidence that the clinical impact of these effects is significant.

IQGAP1 plays an important role in the invasiveness of thyroid cancer

PURPOSE

This study was designed to explore the role of IQGAP1 in the invasiveness of thyroid cancer and its potential as a novel prognostic marker and therapeutic target in this cancer.

EXPERIMENTAL DESIGN

We examined IQGAP1 copy gain and its relationship with clinicopathologic outcomes of thyroid cancer and investigated its role in cell invasion and molecules involved in the process.

RESULTS

We found IQGAP1 copy number (CN) gain ≥ 3 in 1 of 30 (3%), 24 of 74 (32%), 44 of 107 (41%), 8 of 16 (50%), and 27 of 41 (66%) of benign thyroid tumor, follicular variant papillary thyroid cancer (FVPTC), follicular thyroid cancer (FTC), tall cell papillary thyroid cancer (PTC), and anaplastic thyroid cancer, respectively, in the increasing order of invasiveness of these tumors. A similar tumor distribution trend of CN ≥ 4 was also seen. IQGAP1 copy gain was positively correlated with IQGAP1 protein expression. It was significantly associated with extrathyroidal and vascular invasion of FVPTC and FTC and, remarkably, a 50%-60% rate of multifocality and recurrence of BRAF mutation-positive PTC (P = 0.01 and 0.02, respectively). The siRNA knockdown of IQGAP1 dramatically inhibited thyroid cancer cell invasion and colony formation. Coimmunoprecipitation assay showed direct interaction of IQGAP1 with E-cadherin, a known invasion-suppressing molecule, which was upregulated when IQGAP1 was knocked down. This provided a mechanism for the invasive role of IQGAP1 in thyroid cancer. In contrast, IQGAP3 lacked all these functions.

CONCLUSIONS

IQGAP1, through genetic copy gain, plays an important role in the invasiveness of thyroid cancer and may represent a novel prognostic marker and therapeutic target for this cancer.

Genetic alterations in the phosphatidylinositol-3 kinase/Akt pathway in thyroid cancer

BACKGROUND

Aberrant activation of the phosphatidylinositol-3 kinase (PI3K)/Akt pathway plays a fundamental role in thyroid tumorigenesis, particularly in follicular thyroid cancer (FTC) and aggressive thyroid cancer, such as anaplastic thyroid cancer (ATC). As the drivers of this process, many genetic alterations activating the PI3K/Akt pathway have been identified in thyroid cancer in recent years.

SUMMARY

This review summarizes the current knowledge on major genetic alterations in the PI3K/Akt pathway. These include PIK3CA mutations and genomic amplification/copy gain, Ras mutations, PTEN mutations, RET/PTC and PPARgamma/Pax8 rearrangements, as well as amplification/copy gain of PIK3CB, PDK1, Akt, and various receptor tyrosine kinase genes. Most of these genetic alterations are particularly common in FTC and many of them are even more common in ATC; they are generally less common in papillary thyroid cancer (PTC), in which the MAP kinase (MAPK) pathway activated by the BRAF mutation instead plays a major role. Methylation and, thus, epigenetic silencing of PTEN, a major negative regulator of the PI3K/Akt pathway, occurs in close association with activating genetic alterations of the PI3K/Akt pathway, constituting a unique self-enhancement mechanism for this pathway. Many of these genetic alterations are mutually exclusive in differentiated thyroid tumors, but with increasing concurrence from benign tumors to FTC to ATC. RET/PTC, Ras, and receptor tyrosine kinase could dually activate the PI3K/Akt and MAPK pathways. Most cases of ATC harbor genetic alterations in these genes or other genetic combinations that can activate both pathways. It is proposed that genetic alterations in the PI3K/Akt pathway promote thyroid cell transformation to FTC and that genetic alterations in the MAPK pathway promote cell transformation to PTC; accumulation of multiple genetic alterations that can activate both pathways promotes thyroid cancer aggressiveness and progression to ATC.

CONCLUSIONS

Genetic alterations are common in the PI3K/Akt pathway in thyroid cancer and play a fundamental role in the tumorigenesis and progression of this cancer. This provides a strong basis for the emerging development of novel genetic-based diagnostic, prognostic, and therapeutic strategies for thyroid cancer.

BRAF V600E mutation analysis increases diagnostic accuracy for papillary thyroid carcinoma in fine-needle aspiration biopsies

OBJECTIVE

Papillary thyroid carcinoma (PTC) represents the majority of differentiated thyroid cancers, presenting the V600E activating BRAF mutation in 29-83% of cases. The aim of our study is to analyze the influence of BRAF mutation analysis on the diagnostic accuracy of fine-needle aspiration biopsy (FNAB) in patients with suspected PTC.

DESIGN AND METHODS

Thyroid cytoaspirates from 469 nodules (size: 1.1+/-0.8 cm) with ultrasonographic features suspicious of malignant lesion, performed in 374 patients, were submitted to cytological evaluation and to biomolecular analysis, carried out after somatic DNA isolation, specific PCR amplification, and subsequent automated direct sequencing. All PCR fragments were also processed by specific enzyme restriction analysis.

RESULTS

BRAF V600E mutation was found in 48 samples, 41 of which were also cytologically diagnosed as PTC, with histologic confirmation after thyroidectomy. Total thyroidectomy was perfomed also in seven patients with negative cytology but positive BRAF mutation, with histological confirmation of PTC in all. Among the 429 BRAF-negative samples, 407 had negative cytology for PTC, while 22 were diagnosed as suspected PTC and underwent total thyroidectomy with histological diagnosis of PTC in 17 and benign lesion in five. The prevalence of BRAF V600E mutation among histologically diagnosed PTC patients was 64%. Biomolecular analysis significantly increased cytology sensitivity for PTC from 77.3 to 86.7% (P<0.01).

CONCLUSIONS

These data indicate that BRAF V600E mutation analysis can significantly improve FNAB diagnostic accuracy. However, biomolecular analysis is complementary to cytology, which should always be performed.

Biomarker panel diagnosis of thyroid cancer: a critical review

The accurate preoperative diagnosis of thyroid cancer continues to be a significant challenge for those individuals who present with nodular thyroid disease, particularly for tumors with indeterminate cytomorphological features by fine-needle aspiration biopsy. In an effort to develop improved diagnostic tools, a number of studies have investigated the discriminatory potential of many different RNA and protein molecules. However, no individual thyroid cancer biomarker has been found with sufficient sensitivity and specificity. Therefore, research focus has shifted to panels of multiple markers with the hope of improved performance and robustness. A panel comprised of GAL3, CK19 and HBME1 is by far the most studied to date and offers some improvement over individual marker performance alone. However, relatively few marker panels have been studied and their performances and application as diagnostic tests have not been consistently reported. We present a comprehensive review of molecular marker panel studies for thyroid tumors and current issues and challenges. In the future, studies evaluating larger numbers of biomarkers in large patient cohorts are required for the development and validation of a clinically applicable test.

Thyroid-stimulating hormone/cAMP-mediated proliferation in thyrocytes

Current research on thyrotropin-activated proliferation in the thyrocyte needs to be aimed at a better understanding of crosstalk and negative-feedback mechanisms with other proliferative pathways, especially the insulin/IGF-1-induced phosphoinositol-3 kinase pathway and the serum-induced MAPK or Wnt pathways. Convergence of proliferative pathways in mTOR is a hotspot of current research, and combined treatment using double class inhibitors for thyroid cancer may bring some success. New thyroid-stimulating hormone receptor (TSHR)-interacting proteins, a better picture of cAMP targets, a deeper knowledge of the action of the protein kinase A regulatory subunits, especially their interactions with the replication machinery, and a further understanding of mechanisms that lead to cell cycle progression through G₁/S and G₂/M checkpoints are areas that need further elucidation. Finally, massive information coming from microarray data analysis will prompt our understanding of thyroid-stimulating hormone-promoted thyrocyte proliferation in health and disease.