Medroxyprogesterone acetate decreases secretion of interleukin-6 and parathyroid hormone-related protein in a new anaplastic thyroid cancer cell line, KTC-2

HDAC Inhibition Induces PD-L1 Expression in a Novel Anaplastic Thyroid Cancer Cell Line

While papillary thyroid cancer (PTC) has largely favorable prognosis, anaplastic thyroid cancer (ATC) is a rare but extremely aggressive malignancy with grim clinical outcome. Even though new therapeutic options are emerging for ATC, additional preclinical models and novel combinations are needed for specific subsets of patients. We established a novel cell line (PF49) from the malignant pleural effusion of a 68-year-old male patient with ATC that rapidly transformed from a BRAF and TERT promoter mutant PTC. PF49 cells demonstrated a robust migratory activity in vitro and strong invasive capacity in vivo in a pleural carcinosis model. Combined BRAF and MEK inhibition decreased the proliferation and migration of PF49 cells, however could not induce cell death. Importantly, HDAC inhibitor treatment with SAHA or valproic acid induced cell cycle arrest and strongly increased PD-L1 expression of the tumor cells. Induction of PD-L1 expression was also present when paclitaxel-cisplatin chemotherapeutic treatment was combined with HDAC inhibitor treatment. Increased PD-L1 expression after HDAC inhibition was recapitulated in an international ATC cell model. Our data suggest that HDAC inhibition alone or in combination with standard chemotherapy may potentiate anaplastic thyroid cancer cells for immunotherapy.

Interplay of fibroblasts with anaplastic tumor cells promotes follicular thyroid cancer progression

Thyroid cancer is the most common endocrine malignancy. Anaplastic thyroid cancer is one of the most aggressive thyroid tumors. It is known that activation of oncogenes and/or inactivation of tumor suppressor genes in tumor cells promotes tumorigenesis. The microenvironment of the tumor also plays a key role on cancer development and progression in a variety of tumors. However, the mechanisms by which tumor-stroma crosstalk in thyroid cancer remains poorly characterized. In this study we aimed to understand how interactions between fibroblasts and anaplastic thyroid cancer cells contribute to thyroid carcinogenesis. We first characterized the phenotypic changes of human fibroblasts in vitro through co-cultures by using transwells as well as by using anaplastic thyroid cancer cells-derived conditioned media. We found that fibroblasts acquired an activated phenotype or also known as cancer-associated fibroblast phenotype after being in contact with soluble factors secreted from anaplastic thyroid cancer cells, compared to the fibroblasts in mono-cultures. All the changes were partly mediated through Src/Akt activation. Treatment with the antioxidant N-acetyl-cysteine reversed in part the metabolic phenotype of activated fibroblasts. Remarkably, conditioned media obtained from these activated fibroblasts promoted cell proliferation and invasion of follicular thyroid cancer cell line, FTC-133 cells. Thus, a reciprocal and dynamic interaction exists between tumor and stromal cells, which results in the promotion of thyroid tumorigenesis. The present studies have advanced the understanding of the molecular basis of tumor-stroma communications, enabling identification and targeting of tumor-supportive mechanisms for novel treatment modalities.

Methodology, Criteria, and Characterization of Patient-Matched Thyroid Cell Lines and Patient-Derived Tumor Xenografts

OBJECTIVE

To investigate the molecular underpinnings of thyroid cancer, preclinical cell line models are crucial; however, ∼40% of these have been proven to be either duplicates of existing thyroid lines or even nonthyroid-derived lines or are not derived from humans at all. Therefore, we set out to establish procedures and guidelines that should proactively avoid these problems, which facilitated the creation of criteria to make valid preclinical models for thyroid cancer research.

DESIGN

Based on our recommendations, we systematically characterized all new cell lines that we generated by a standardized approach that included (1) determination of human origin, (2) exclusion of lymphoma, (3) DNA fingerprinting and histological comparisons to establish linkage to presumed tissue of origin, (4) examining thyroid differentiation by screening two to three thyroid markers, (5) examination of biological behavior (growth rate, tumorigenicity), and (6) presence of common thyroid cancer genetic changes (TP53, BRAF, PTEN, PIK3CA, RAS, TERT promoter, RET/PTC, PAX8/PPARγ, NF1, and EIF1AX).

RESULTS

We established seven new thyroid cell lines (LAM136, EAM306, SDAR1, SDAR2, JEM493, THJ529, and THJ560) out of 294 primary culture attempts, and 10 patient-derived tumor xenografts (PDTXs; MC-Th-95, MC-Th-374, MC-Th-467, MC-Th-491, MC-Th-493, MC-Th-504, MC-Th-524, MC-Th-529, MC-Th-560, and MC-Th-562) out of 67 attempts. All were successfully validated by our protocols.

CONCLUSIONS

This standardized approach for cell line and PDTX characterization should prevent (or detect) future cross-contamination and ensure that only valid preclinical models are used for thyroid cancer research.

Wild-type and specific mutant androgen receptor mediates transcription via 17β-estradiol in sex hormone-sensitive cancer cells

We previously encountered regulatory processes wherein dihydrotestosterone (DHT) exerted its inhibitory effect on parathyroid hormone‐related protein (PTHrP) gene repression through the estrogen receptor (ER)α, but not the androgen receptor (AR), in breast cancer MCF‐7 cells. Here, we investigated whether such aberrant ligand‐nuclear receptor (NR) interaction is present in prostate cancer LNCaP cells. First, we confirmed that LNCaP cells expressed large amounts of AR at negligible levels of ERα/β or progesterone receptor. Both suppression of PTHrP and activation of prostate‐specific antigen genes were observed after independent administration of 17β‐estradiol (E2), DHT, or R5020. Consistent with the notion that the LNCaP AR lost its ligand specificity due to a mutation (Thr‐Ala877), experiments with siRNA targeting the respective NR revealed that the AR monopolized the role of the mediator of shared hormone‐dependent regulation, which was invariably associated with nuclear translocation of this mutant AR. Microarray analysis of gene regulation by DHT, E2, or R5020 disclosed that more than half of the genes downstream of the AR (Thr‐Ala877) overlapped in the LNCaP cells. Of particular interest, we realized that the AR (wild‐type [wt]) and AR (Thr‐Ala877) were equally responsible for the E2‐AR interactions. Fluorescence microscopy experiments demonstrated that both EGFP‐AR (wt) and EGFP‐AR (Thr‐Ala877) were exclusively localized within the nucleus after E2 or DHT treatment. Furthermore, reporter assays revealed that some other cancer cells exhibited aberrant E2‐AR (wt) signaling similar to that in the LNCaP cells. We herein postulate the presence of entangled interactions between wt AR and E2 in certain hormone‐sensitive cancer cells. J. Cell. Physiol. 230: 1594–1606, 2015. © 2014 The Authors. Journal of Cellular Physiology Published by Wiley Periodicals, Inc.

Medroxyprogesterone acetate differentially regulates interleukin (IL)-12 and IL-10 in a human ectocervical epithelial cell line in a glucocorticoid receptor (GR)-dependent manner

Medroxyprogesterone acetate (MPA), designed to mimic the actions of the endogenous hormone progesterone (P4), is extensively used by women as a contraceptive and in hormone replacement therapy. However, little is known about the steroid receptor-mediated molecular mechanisms of action of MPA in the female genital tract. In this study, we investigated the regulation of the pro-inflammatory cytokine, interleukin (IL)-12, and the anti-inflammatory cytokine IL-10, by MPA versus P4, in an in vitro cell culture model of the female ectocervical environment. This study shows that P4 and MPA significantly increase the expression of the IL-12p40 and IL-12p35 genes, whereas IL-10 gene expression is suppressed in a dose-dependent manner. Moreover, these effects were abrogated when reducing the glucocorticoid receptor (GR) levels with siRNA. Using a combination of chromatin immunoprecipitation (ChIP), siRNA, and re-ChIP assays, we show that recruitment of the P4- and MPA-bound GR to the IL-12p40 promoter requires CCAAT enhancer-binding protein (C/EBP)-β and nuclear factor κB (NFκB), although recruitment to the IL-10 promoter requires signal transducer and activator of transcription (STAT)-3. These results suggest that both P4 and MPA may modulate inflammation in the ectocervix via this genomic mechanism.

Potency of progestogens used in hormonal therapy: toward understanding differential actions

Progestogens are widely used in contraception and in hormone therapy. Biochemical and molecular biological evidence suggests that progestogens differ widely in their affinities and transcriptional effects via different steroid receptors, and hence cannot be considered as a single class of compounds. Consistent with these observations, recent clinical evidence suggests that, despite their similar progestogenic actions, these differences underlie different side-effect profiles for cardiovascular disease and susceptibility to infectious diseases. However, choice of progestogen for maximal benefit and minimal side-effects is hampered by insufficient comparative clinical and molecular studies to understand their relative mechanisms of action, as well as their relative potencies for different assays and clinical effects. This review evaluates the usage, meaning and significance of the terms affinity, potency and efficacy in different models systems, with a view to improved understanding of their physiological and pharmacological significance. This article is part of a Special Issue entitled 'Menopause'.

Curcumin Enhances Docetaxel-Induced Apoptosis of 8505C Anaplastic Thyroid Carcinoma Cells

BACKGROUND

Anaplastic thyroid cancer (ATC) is one of the most aggressive malignancies in humans, and its progression is poorly controlled by existing therapeutic methods. Curcumin has been shown to suppress inflammation and angiogenesis. In this study, we evaluated whether curcumin could augment docetaxel-induced apoptosis of ATC cells. We also analyzed changes in nuclear factor κB (NF-κB) and cyclooxygenase-2 (COX-2) expression levels to delineate possible mechanisms of their combined action.

METHODS

ATC cells were cultured and treated with curcumin and docetaxel alone or in combination. The effects on cell viability were determined by MTS assay. Apoptosis was assessed by annexin V staining and confirmed by flow cytometric analysis. Caspase, COX-2, NF-κB levels were assayed by Western blotting.

RESULTS

Curcumin combined with docetaxel led to lower cell viability than treatment with docetaxel or curcumin alone. Annexin V staining followed by flow cytometric analysis demonstrated that curcumin treatment enhanced the docetaxel-induced apoptosis of ATC cells. Additionally, curcumin inhibited docetaxel-induced p65 activation and COX-2 expression.

CONCLUSION

We conclude that curcumin may enhance docetaxel's antitumor activity in ATC cells by interfering with NF-κB and COX-2. Our results suggest that curcumin may emerge as an attractive therapeutic candidate to enhance the antitumor activity of taxanes in ATC treatment.

Analysis of multiple markers for cancer stem-like cells in human thyroid carcinoma cell lines

Cancer stem-like cells (CSCs) play important roles in cancer initiation and progression. CSCs have been isolated using several markers, but those for thyroid CSCs remain to be confirmed. We therefore conducted a comprehensive search for thyroid CSC markers. Expression of nine cell surface markers (CD13, CD15, CD24, CD44, CD90, CD117, CD133, CD166, and CD326) and aldehyde dehydrogenase (ALDH) activity, which are CSC markers in various solid cancers, and the ability to form spheres in vitro and tumors in vivo were investigated using eight thyroid cancer cell lines (FRO, KTC1/2/3, TPC1, WRO, ACT1, and 8505C). Among these, four cell lines (FRO, KTC3, ACT1, and 8505C) possessed the both abilities; however, common markers indicative of CSCs were not observed. The pattern of ability to form spheres was completely matched to that of tumor formation, suggesting that our sphere assay is valuable for assessment of tumor-forming ability. Next, the cells were sorted using these markers and subjected to the sphere assay. In three cell lines (FRO, KTC3, and ACT1), ALDH(pos) cells showed higher sphere forming ability than ALDH(neg) cells but not in other cells. CD326(hi) also appeared to be a candidate marker only in FRO cells. However, these subpopulations did not follow a classical hierarchical model because ALDH(neg) and CD326(low) fractions also generated ALDH(pos) and CD326(hi) cells, respectively. These data suggest that ALDH activity is probably a major candidate marker to enrich thyroid CSCs but not universal; other markers such as CD326 that regulate different CSC properties may exist.

Progestogens used in postmenopausal hormone therapy: differences in their pharmacological properties, intracellular actions, and clinical effects

The safety of progestogens as a class has come under increased scrutiny after the publication of data from the Women's Health Initiative trial, particularly with respect to breast cancer and cardiovascular disease risk, despite the fact that only one progestogen, medroxyprogesterone acetate, was used in this study. Inconsistency in nomenclature has also caused confusion between synthetic progestogens, defined here by the term progestin, and natural progesterone. Although all progestogens by definition have progestational activity, they also have a divergent range of other properties that can translate to very different clinical effects. Endometrial protection is the primary reason for prescribing a progestogen concomitantly with postmenopausal estrogen therapy in women with a uterus, but several progestogens are known to have a range of other potentially beneficial effects, for example on the nervous and cardiovascular systems. Because women remain suspicious of the progestogen component of postmenopausal hormone therapy in the light of the Women's Health Initiative trial, practitioners should not ignore the potential benefits to their patients of some progestogens by considering them to be a single pharmacological class. There is a lack of understanding of the differences between progestins and progesterone and between individual progestins differing in their effects on the cardiovascular and nervous systems, the breast, and bone. This review elucidates the differences between the substantial number of individual progestogens employed in postmenopausal hormone therapy, including both progestins and progesterone. We conclude that these differences in chemical structure, metabolism, pharmacokinetics, affinity, potency, and efficacy via steroid receptors, intracellular action, and biological and clinical effects confirm the absence of a class effect of progestogens.

Imatinib enhances docetaxel-induced apoptosis through inhibition of nuclear factor-κB activation in anaplastic thyroid carcinoma cells

BACKGROUND

We previously reported the partial effectiveness of imatinib (also known as STI571, Glivec, or Gleevec) on anaplastic thyroid cancer (ATC) cells. Imatinib is a selective tyrosine kinase inhibitor that has been used for various types of cancer treatments. Recently, several reports have demonstrated that imatinib enhanced the sensitivity of cancer cells to other anticancer drugs. In this study, therefore, we investigated whether imatinib enhances the antitumor activity of docetaxel in ATC cells.

METHODS

Two ATC cell lines, FRO and KTC-2, were treated with imatinib and/or docetaxel. Cell survival assay and flow cytometry for annexin V were used to assess the induction of apoptosis. Changes of pro- and antiapoptotic factors were determined by Western blot. Nuclear factor-κB (NF-κB) activity was measured by DNA-binding assay. Tumor growth was also investigated in vivo.

RESULTS

The combined treatment significantly enhanced apoptosis compared with single treatment. ATC cells themselves expressed high levels of antiapoptotic factors, X-linked inhibitor of apoptosis (XIAP), and survivin. The treatment with docetaxel alone further increased their expressions; however, the combined treatment blocked the inductions. Although imatinib alone had no effect on NF-κB background levels, combined treatment significantly suppressed the docetaxel-induced NF-κB activation. Further, the combined administration of the drugs also showed significantly greater inhibitory effect on tumor growth in mice xenograft model.

CONCLUSIONS

Imatinib enhanced antitumor activity of docetaxel in ATC cells. Docetaxel seemed to induce both pro- and antiapoptotic signaling pathways in ATC cells, and imatinib blocked the antiapoptotic signal. Thus, docetaxel combined with imatinib emerges as an attractive strategy for the treatment of ATC.

Association of the oncostatin m receptor gene polymorphisms with papillary thyroid cancer in the korean population

Objectives

To investigate the association between papillary thyroid cancer (PTC) and single nucleotide polymorphisms (SNPs) of oncostatin M receptor (OSMR) in the Korean population.

Methods

Retrospective case-control study was done. Eighty-five patients with PTC and 287 controls were studied. One missense SNP (rs2278329, Asp553Asn) and one promoter SNP (rs2292016, -100 G/T) of the OSMR gene were genotyped by direct sequencing. Genetic data were analyzed using the SNPStats, Helixtree, and SNPAnalyzer Pro. PTC patients were dichotomized and compared with respect to the clinicopathologic characteristics.

Results

There was no association between genotypes and allele frequencies of OSMR SNPs (rs2278329 and rs2292016) and PTC susceptibility. SNP rs2278329 was significantly associated with tumor size (dominant model; P=0.028; odds ratio [OR], 2.71; 95% confidence interval [CI], 1.12 to 6.57). The A allele was higher in sizes large than 1 cm (32.5% vs. 16.7%; P=0.018; OR, 2.41; 95% CI, 1.17 to 4.98). Regarding the number of tumors, we found no significant association with genotype, however, the A allele was higher in patients with multifocaltiy (33.3% vs. 19.1%; P=0.040; OR, 2.12; 95% CI, 1.03 to 4.34).

Conclusion

The results suggest that OSMR polymorphism rs2278329 is associated with clinicopathologic characteristics of the tumor growth and multifocality development.

Molecular mechanisms of steroid receptor-mediated actions by synthetic progestins used in HRT and contraception

Synthetic progestins are used by millions of women as contraceptives and in hormone replacement therapy (HRT), although their molecular mechanisms of action are not well understood. The importance of investigating these mechanisms, as compared to those of progesterone, has been highlighted by clinical evidence showing that medroxyprogesterone acetate (MPA), a first generation progestin, increases the risk of breast cancer and coronary heart disease in HRT users. A diverse range of later generation progestins with varying structures and pharmacological properties is available for therapeutic use and it is becoming clear that different progestins elicit beneficial and adverse effects to different extents. These differences in biological activity are likely to be due to many factors including variations in dose, metabolism, pharmacokinetics, bioavailability, and regulation of, and/or binding, to serum-binding proteins and steroidogenic enzymes. Since the intracellular effects on gene expression and cell signaling of steroids are mediated via intracellular steroid receptors, differential actions via the progesterone and other steroid receptors and their isoforms, are likely to be the major cause of differential intracellular actions of progestins. Since many progestins bind not only to the progesterone receptor, but also to the glucocorticoid, androgen, mineralocorticoid, and possibly the estrogen receptors, it is plausible that synthetic progestins exert therapeutic actions as well as side-effects via some of these receptors. Here we review the molecular mechanisms of intracellular actions of old (MPA, norethisterone, levonorgestrel, gestodene) vs. new (drospirenone, dienogest, trimegestone) generation progestins, via steroid receptors.

Negative regulation of parathyroid hormone-related protein expression by steroid hormones

Elevated parathyroid hormone-related protein (PTHrP) is responsible for humoral hypercalcemia of malignancy (HHM), which is of clinical significance in treatment of terminal patients with malignancies. Steroid hormones were known to cause suppression of PTHrP expression. However, detailed studies linking multiple steroid hormones to PTHrP expression are lacking. Here we studied PTHrP expression in response to steroid hormones in four cell lines with excessive PTHrP production. Our study established that steroid hormones negatively regulate PTHrP expression. Vitamin D receptor, estrogen receptor α, glucocorticoid receptor, and progesterone receptor, were required for repression of PTHrP expression by the cognate ligands. A notable exception was the androgen receptor, which was dispensable for suppression of PTHrP expression in androgen-treated cells. We propose a pathway(s) involving nuclear receptors to suppress PTHrP expression.

Potential utility and limitations of thyroid cancer cell lines as models for studying thyroid cancer

BACKGROUND

Tumor-derived cell lines are widely used to study the mechanisms involved in thyroid carcinogenesis but recent studies have reported redundancy among thyroid cancer cell lines and identification of some "thyroid cell lines" that are likely not of thyroid origin.

SUMMARY

In this review, we have summarized the uses, the limitations, and the existing problems associated with the available follicular cell-derived thyroid cancer cell lines. There are some limitations to the use of cell lines as a model to "mimic" in vivo tumors. Based on the gene expression profiles of thyroid cell lines originating from tumors of different types it has become apparent that some of the cell lines are closely related to each other and to those of undifferentiated carcinomas. Further, many cell lines have lost the expression of thyroid-specific genes and have altered karyotypes, while they exhibit activation of several oncogenes (BRAF, v-raf murine sarcoma viral oncogene homolog B1; RAS, rat sarcoma; and RET/PTC, rearranged in transformation/papillary thyroid carcinoma) and inactivation of tumor suppressor gene (TP53) which is known to be important for thyroid tumorigenesis.

CONCLUSIONS

A careful selection of thyroid cancer cell lines that reflect the major characteristics of a particular type of thyroid cancer being investigated could be used as a good model system to analyze the signaling pathways that may be important in thyroid carcinogenesis. Further, the review of literature also suggests that some of the limitations can be overcome by using multiple cell lines derived from the same type of tumor.

Deoxyribonucleic acid profiling analysis of 40 human thyroid cancer cell lines reveals cross-contamination resulting in cell line redundancy and misidentification

CONTEXT

Cell lines derived from human cancers provide critical tools to study disease mechanisms and develop novel therapies. Recent reports indicate that up to 36% of cell lines are cross- contaminated.

OBJECTIVE

We evaluated 40 reported thyroid cancer-derived cell lines using short tandem repeat and single nucleotide polymorphism array analysis.

RESULTS

Only 23 of 40 cell lines tested have unique genetic profiles. The following groups of cell lines are likely derivatives of the same cell line: BHP5-16, BHP17-10, BHP14-9, and NPA87; BHP2-7, BHP10-3, BHP7-13, and TPC1; KAT5, KAT10, KAT4, KAT7, KAT50, KAK1, ARO81-1, and MRO87-1; and K1 and K2. The unique cell lines include BCPAP, KTC1, TT2609-C02, FTC133, ML1, WRO82-1, 8505C, SW1736, Cal-62, T235, T238, Uhth-104, ACT-1, HTh74, KAT18, TTA1, FRO81-2, HTh7, C643, BHT101, and KTC-2. The misidentified cell lines included the DRO90-1, which matched the melanoma-derived cell line, A-375. The ARO81-1 and its derivatives matched the HT-29 colon cancer cell line, and the NPA87 and its derivatives matched the M14/MDA-MB-435S melanoma cell line. TTF-1 and Pax-8 mRNA levels were determined in the unique cell lines.

CONCLUSIONS

Many of these human cell lines have been widely used in the thyroid cancer field for the past 20 yr and are not only redundant, but not of thyroid origin. These results emphasize the importance of cell line integrity, and provide the short tandem repeat profiles for a panel of thyroid cancer cell lines that can be used as a reference for comparison of cell lines from other laboratories.

Dehydroxymethylepoxyquinomicin, a novel nuclear Factor-kappaB inhibitor, enhances antitumor activity of taxanes in anaplastic thyroid cancer cells

Nuclear factor kappaB (NF-kappaB), as an antiapoptotic factor, crucially affects the outcomes of cancer treatments, being one of the major culprits of resistance to chemotherapy. In this study, we investigated whether dehydroxymethylepoxyquinomicin (DHMEQ), a novel NF-kappaB inhibitor, can enhance antitumor activities of taxanes in anaplastic thyroid cancer (ATC) cells. Taxanes induced NF-kappaB activation in ATC cells, which could compromise the therapeutic effect of the drugs. However, DHMEQ, by inhibiting the nuclear translocation of NF-kappaB, completely suppressed the DNA binding capacities of NF-kappaB and lowered the levels of nuclear NF-kappaB protein. Compared with single treatment (either taxane or DHMEQ), the combined treatment strongly potentiated apoptosis, confirmed by cell survival assay; Western blotting for poly (ADP-ribose) polymerase, caspase 3, X-linked inhibitor of apoptosis, and survivin; and flow cytometry for annexin V. Furthermore, we also demonstrate for the first time that the combined treatment showed significantly greater inhibitory effect on tumor growth in a nude mice xenograft model. These findings suggest that taxanes are able to induce NF-kappaB activation in ATC cells, which could attenuate antitumor activities of the drugs, but inhibition of NF-kappaB by DHMEQ creates a chemosensitive environment and greatly enhances apoptosis in taxanes-treated ATC cells in vitro and in vivo. Thus, DHMEQ may emerge as an attractive therapeutic strategy to enhance the response to taxanes in ATCs.

Oncogenic role of miR-17-92 cluster in anaplastic thyroid cancer cells

Micro RNAs (miRNAs) are non-coding small RNAs and constitute a novel class of negative gene regulators that are found in both plants and animals. Several miRNAs play crucial roles in cancer cell growth. To identify miRNAs specifically deregulated in anaplastic thyroid cancer (ATC) cells, we performed a comprehensive analysis of miRNA expressions in ARO cells and primary thyrocytes using miRNA microarrays. MiRNAs in a miR-17-92 cluster were overexpressed in ARO cells. We confirmed the overexpression of those miRNAs by Northern blot analysis in ARO and FRO cells. In 3 of 6 clinical ATC samples, miR-17-3p and miR-17-5p were robustly overexpressed in cancer lesions compared to adjacent normal tissue. To investigate the functional role of these miRNAs in ATC cells, ARO and FRO cells were transfected with miRNA inhibitors, antisense oligonucleotides containing locked nucleic acids. Suppression of miR-17-3p caused complete growth arrest, presumably due to caspase activation resulting in apoptosis. MiR-17-5p or miR-19a inhibitor also induced strong growth reduction, but only miR-17-5p inhibitor led to cellular senescence. On the other hand, miR-18a inhibitor only moderately attenuated the cell growth. Thus, we have clarified functional differences among the members of the cluster in ATC cells. In conclusion, these findings suggest that the miR-17-92 cluster plays an important role in certain types of ATCs and could be a novel target for ATC treatment.

Circulating interleukin-6 as a tumor marker for hepatocellular carcinoma

BACKGROUND

A large amount of evidence suggests a possible role of interleukin-6 (IL-6) in the pathogenesis of hepatocellular carcinoma (HCC).

PATIENTS AND METHODS

We studied both IL-6 and A(1)FP in patients with HCC, non-neoplastic liver disease or in healthy controls.

RESULTS

IL-6 titers were four-fold higher in cancer than in cirrhotic patients and 25-fold higher than in healthy controls. As for alpha1-fetoprotein (A(1)FP) titers, the highest levels were observed in cancer patients. Receiver operating characteristic (ROC) curves analysis demonstrated that IL-6 is significantly more discriminant than A(1)FP, with 'optimal' cut-off values of 7.9 pg/ml (sensitivity = 0.83, specificity = 0.83, efficiency = 0.83). The ROC curves used to distinguish HCC from cirrhotic patients only, showed higher discriminant power of IL-6 versus A(1)FP titers, with a new cut-off value of 12 pg/ml (sensitivity = 0.73, specificity = 0.87, efficiency = 0.8). Discriminant analysis on HCC and non-HCC subjects yielded sensitivity, specificity and efficiency rates of 77%, 93% and 88%, respectively. The overall efficiency of the two tests combined was 82%.

CONCLUSIONS

IL-6 could be considered a promising tumor marker for HCC. In particular, the diagnostic value of the test is significantly increased when combined with A(1)FP.

Additive antitumor effects of gefitinib and imatinib on anaplastic thyroid cancer cells

PURPOSE

Anaplastic thyroid cancer (ATC) is one of the most aggressive malignancies. Although multidisciplinary treatments have been introduced, patients with this disease rarely survive longer than 1 year. These findings prompted us to investigate the antitumor activity of molecular targeting agents in thyroid cancer cells.

METHODS

Two tyrosine kinase inhibitors, gefitinib and imatinib, were tested in a poorly differentiated thyroid cancer cell line, KTC-1, and two ATC cell lines, KTC-2 and KTC-3.

RESULTS

All cell lines expressed not only a target molecule of gefitinib, HER1, but also a cognate receptor, HER2. They also expressed target molecules of imatinib, c-ABL and platelet-derived growth factor receptors at various levels. Both agents had modest antitumor activity in these cell lines. Combined treatment with gefitinib and imatinib led to an additional antitumor effect. Each agent induced apoptosis and their combined treatment enhanced apoptosis associated with the down-regulation of antiapoptotic proteins, Bcl-2 and Bcl-xL. Moreover, their combined treatment additionally inhibited the growth of KTC-3 xenografts in nude mice.

CONCLUSIONS

These are the first findings to suggest that both gefitinib and imatinib have antitumor activity against ATC cells and that their combined use has greater activity than either drug alone.

Paneling human thyroid cancer cell lines for candidate proteins for targeted anti-angiogenic therapy

Tumor angiogenesis is believed to result from an imbalance of pro- and anti-angiogenic factors, some of which are candidates for targeted therapy. Such therapy has raised hopes for patients with undifferentiated thyroid carcinomas, who are facing a grave prognosis with a survival of only months. In this study, in vivo growth of xenografted human thyroid carcinomas unexpectedly responded quite differently to neutralizing anti-vascular endothelial growth factor (VEGF) antibody. In particular, lasting inhibition as well as accelerated growth occurred after treatment. Consequently, a panel of anti-angiogenic factors was addressed in a representative sample of thyroid carcinoma lines. VEGF, fibroblast growth factor (FGF-2), and endostatin were demonstrated by Western blotting and EIA, whereas PDGF-A, PDGF-B, and IL-6 were negative. Quantification of VEGF, FGF-2, and endostatin revealed a wide range of concentrations from 500 to 4,200 pg/ml VEGF, 5 to 60 pg/ml FGF-2, and 50 to 300 pg/ml endostatin, not related to a particular histologic thyroid carcinoma background. Angiostatin (kringles 1-3) was detected in all, but one of the cell lines. Finally, aaATIII was confirmed in FTC133 cells. These data highlight the complex regulation of angiogenesis in thyroid carcinoma cell lines and suggest that the array of angiogenic factors differs markedly between individual cell lines. For the first time, angiostatin, endostatin, and possibly also aaATIII are identified as novel candidate regulators of angiogenesis in thyroid carcinoma cells.

Synthetic progestins used in HRT have different glucocorticoid agonist properties

The synthetic progestins, medroxyprogesterone acetate (MPA) and norethisterone acetate (NET-EN or NET-A), are widely used as female contraceptive agents and in hormone replacement therapy (HRT). Competitive binding revealed that MPA displays a higher relative binding affinity than NET-A and progesterone (prog) for the human GR (Kd of 4.2 nM for dexamethasone (dex) and Ki's of 10.8, 270 and 215 nM for MPA, NET-A and prog, respectively). Furthermore, MPA displays much greater glucocorticoid (GC) transactivation agonist potency than NET-A or prog (EC50s of 1.1, 7.2, >1000 and 280 nM for dex, MPA, NET-A and prog, respectively) and much greater GC agonist potency for transrepression than NET-A or prog (EC50s of 0.21, 2.7, >100 and 26 nM for dex, MPA, NET-A and prog, respectively). In addition, MPA induces phosphorylation of the GR at Ser 211 to a much greater extent than NET-A or prog and protects the GR from partial trypsin digestion in vitro to a much greater extent than NET-A or prog at saturating concentrations. Together these results suggest that the differences in biological activity of the progestins are not merely due to differences in their affinity for the GR but also due to the induction of different conformational changes in the liganded-GR. MPA and NET-A therefore display very different GC-like properties compared to each other and to prog, and are likely to exhibit different side effects via the GR.

Induction of thyroid cancer cell apoptosis by a novel nuclear factor kappaB inhibitor, dehydroxymethylepoxyquinomicin

PURPOSE

The objective of the study was to determine the effects of a novel selective nuclear factor kappaB (NF-kappaB) inhibitor, dehydroxymethylepoxyquinomicin (DHMEQ), in thyroid carcinoma cells in vitro and in vivo and to additionally elucidate the molecular mechanisms underlying the action of this chemotherapeutic agent.

EXPERIMENTAL DESIGN

In the in vitro experiments, the induction of apoptosis by DHMEQ in various human thyroid carcinoma cell types was determined by flow cytometry analysis of annexin-V binding and the caspase activation by Western blotting. For the in vivo study, female nu/nu mice were xenografted with s.c. FRO thyroid tumors. DHMEQ solution was injected i.p. at a dose of 8 mg/kg/day for two weeks. Tumor dimensions were monitored twice weekly, and apoptosis in tumor specimens was determined by terminal deoxynucleotidyl transferase-mediated nick end labeling staining.

RESULTS

Treatment with DHMEQ substantially inhibited the translocation of p65 and p50 NF-kappaB subunits to the nucleus, the DNA-binding activity of the RelA/p65, NF-kappaB-dependent expression of the inhibitor of apoptosis (IAP)-family proteins, cIAP-1, cIAP-2, and XIAP, and the de novo synthesis of inhibitor of nuclear factor kappaB alpha. At concentration levels ranging from 0.1 to 5 microg/ml, DHMEQ induced a caspase-mediated apoptotic response that could be abrogated by the c-Jun NH(2)-terminal kinase inhibitor SP600125 but not by either mitogen-activated protein/extracellular signal-regulated kinase kinase or p38 inhibitors. In contrast, normal human thyrocytes were resistant to DHMEQ-induced apoptosis. At higher doses of DHMEQ we observed the necrotic-like killing of both normal and malignant thyrocytes, which was resistant to mitogen-activated protein kinase inhibitors. In nude mice DHMEQ substantially inhibited tumor growth without observable side effects, and increased numbers of apoptotic cells were observed in the histologic sections of tumors treated with DHMEQ.

CONCLUSIONS

Our results show the potential usefulness of the novel NF-kappaB inhibitor, DHMEQ, in future therapeutic strategies for the treatment of thyroid cancers that do not respond to conventional approaches.