Dual inhibition of HDAC and EGFR signaling with CUDC-101 induces potent suppression of tumor growth and metastasis in anaplastic thyroid cancer

Discovery of 4-((3,4-dichlorophenyl)amino)-2-methylquinolin-6-ol derivatives as EGFR and HDAC dual inhibitors

In patients with non-small cell lung cancer (NSCLC), the standard therapy consists of selective tyrosine kinase inhibitors that target epidermal growth factor receptors (EGFR). Nonetheless, their clinical utility is primarily limited by the development of resistance to drugs. HDAC inhibitors have been shown in studies to reduce the level of EGFR that is expressed and downregulate the EGFR-induced phosphorylation of AKT and ERK. Therefore, dual inhibitors of EGFR and HDAC provide a potential approach as combination treatment synergistically inhibited the growth of NSCLC. Herein, we examined the EGFR inhibition effect of twenty compounds which designed and synthesized by us previously. Among them, compounds 12c and 12d exhibited powerful antiproliferative activity against the NCI-H1975 cell line with IC50 values of 0.48 ± 0.07 and 0.35 ± 0.02 μM, correspondingly. In cell-free kinase assays, both 12c and 12d demonstrated target-specific EGFR inhibition against wild type (EGFRwt). Furthermore, the expression of EGFR and phosphorylation of the EGF-induced pathways were significantly suppressed under the treatment of 12c and 12d. Besides, both histones H3 and H4 exhibited increased levels of acetylation following 12c and 12d treatment. The animal experiments shown that 12d could prevent the growth of tumor, inhibited the expression of EGFR and the phosphorylation levels of p70 S6K, AKT and p38 MAPK in vivo, and did not cause organ damage to the mice during the experiment. Overall, the results illustrated that compound 12c and 12d could serve as effective EGFR and HDAC dual inhibitors in NSCLC cells. Our work offers an alternative strategy for NSCLC therapy.

CUDC‑101 is a potential target inhibitor for the EGFR‑overexpression bladder cancer cells

Bladder cancer is one of the most common urological malignancies worldwide. The molecular mechanism underlying its development is complex, but its carcinogenesis has been proposed to occur with cell proliferation and resistance to apoptosis, driven by the signaling activity of abundant EGFR and receptor tyrosine‑protein kinase erbB‑2. In the present study, T24 bladder cancer cell lines with EGFR‑overexpression were constructed, before the multi‑target inhibitor CUDC‑101 was used to investigate its potential as a targeted therapeutic agent for bladder cancer using chemosensitivity methods. The results showed that CUDC‑101 induced cytotoxic effects, inhibited growth vitality and proliferation in a dose‑dependent manner. CUDC‑101 also altered the skeletal morphology and microfilament structure, while blocking cell cycle progression and causing apoptosis. These results supported the proposed cytotoxic effects of CUDC‑101, in addition to its inhibitory effects on cell division and proliferation in EGFR‑overexpressing bladder cancer cells. Therefore CUDC‑101 may to be a potential therapeutic option for the treatment of bladder cancer.

Sex Differences in Differentiated Thyroid Cancer

Background: Sex dimorphism strongly impacts tumor biology, with most cancers having a male predominance. Uniquely, thyroid cancer (TC) is the only nonreproductive cancer with striking female predominance with three- to four-fold higher incidence among females, although males generally have more aggressive disease. The molecular basis for this observation is not known, and current approaches in treatment and surveillance are not sex specific. Summary: Although TC has overall good prognosis, 6-20% of patients develop regional or distant metastasis, one third of whom are not responsive to conventional treatment approaches and suffer a 10-year survival rate of only 10%. More efficacious treatment strategies are needed for these aggressive TCs, as tyrosine kinase inhibitors and immunotherapy have major toxicities without demonstrable overall survival benefit. Emerging evidence indicates a role of sex hormones, genetics, and the immune system in modulation of both risk for TC and its progression in a sex-specific manner. Conclusion: Greater understanding of the molecular mechanisms underlying sex differences in TC pathogenesis could provide insights into the development of sex-specific, targeted, and effective strategies for prevention, diagnosis, and management. This review summarizes emerging evidence for the importance of sex in the pathogenesis, progression, and response to treatment in differentiated TC with emphasis on the role of sex hormones, genetics, and the immune system.

Targeting Histone Deacetylases: Opportunities for Cancer Treatment and Chemoprevention

The dysregulation of gene expression is a critical event involved in all steps of tumorigenesis. Aberrant histone and non-histone acetylation modifications of gene expression due to the abnormal activation of histone deacetylases (HDAC) have been reported in hematologic and solid types of cancer. In this sense, the cancer-associated epigenetic alterations are promising targets for anticancer therapy and chemoprevention. HDAC inhibitors (HDACi) induce histone hyperacetylation within target proteins, altering cell cycle and proliferation, cell differentiation, and the regulation of cell death programs. Over the last three decades, an increasing number of synthetic and naturally derived compounds, such as dietary-derived products, have been demonstrated to act as HDACi and have provided biological and molecular insights with regard to the role of HDAC in cancer. The first part of this review is focused on the biological roles of the Zinc-dependent HDAC family in malignant diseases. Accordingly, the small-molecules and natural products such as HDACi are described in terms of cancer therapy and chemoprevention. Furthermore, structural considerations are included to improve the HDACi selectivity and combinatory potential with other specific targeting agents in bifunctional inhibitors and proteolysis targeting chimeras. Additionally, clinical trials that combine HDACi with current therapies are discussed, which may open new avenues in terms of the feasibility of HDACi’s future clinical applications in precision cancer therapies.

RAC1 Alterations Induce Acquired Dabrafenib Resistance in Association with Anaplastic Transformation in a Papillary Thyroid Cancer Patient

BRAF-activating mutations are the most frequent driver mutations in papillary thyroid cancer (PTC). Targeted inhibitors such as dabrafenib have been used in advanced BRAF-mutated PTC; however, acquired resistance to the drug is common and little is known about other effectors that may play integral roles in this resistance. In addition, the induction of PTC dedifferentiation into highly aggressive KRAS-driven anaplastic thyroid cancer (ATC) has been reported. We detected a novel RAC1 (P34R) mutation acquired during dabrafenib treatment in a progressive metastatic lesion with ATC phenotype. To identify a potential functional link between this novel mutation and tumor dedifferentiation, we developed a cell line derived from the metastatic lesion and compared its behavior to isogenic cell lines and primary tumor samples. Our data demonstrated that RAC1 mutations induce changes in cell morphology, reorganization of F-actin almost exclusively at the cell cortex, and changes in cell adhesion properties. We also established that RAC1 amplification, with or without mutation, is sufficient to drive cell proliferation and resistance to BRAF inhibition. Further, we identified polyploidy of chromosome 7, which harbors RAC1, in both the metastatic lesion and its derived cell line. Copy number amplification and overexpression of other genes located on this chromosome, such as TWIST1, EGFR, and MET were also detected, which might also lead to dabrafenib resistance. Our study suggests that polyploidy leading to increased expression of specific genes, particularly those located on chromosome 7, should be considered when analyzing aggressive thyroid tumor samples and in further treatments.

Next-Generation Molecular Imaging of Thyroid Cancer

An essential aspect of thyroid cancer (TC) management is personalized and precision medicine. Functional imaging of TC with radioiodine and [18F]FDG has been frequently used in disease evaluation for several decades now. Recently, advances in molecular imaging have led to the development of novel tracers based on aptamer, peptide, antibody, nanobody, antibody fragment, and nanoparticle platforms. The emerging targets-including HER2, CD54, SHP2, CD33, and more-are promising targets for clinical translation soon. The significance of these tracers may be realized by outlining the way they support the management of TC. The provided examples focus on where preclinical investigations can be translated. Furthermore, advances in the molecular imaging of TC may inspire the development of novel therapeutic or theranostic tracers. In this review, we summarize TC-targeting probes which include transporter-based and immuno-based imaging moieties. We summarize the most recent evidence in this field and outline how these emerging strategies may potentially optimize clinical practice.

Hybrid Drugs-A Strategy for Overcoming Anticancer Drug Resistance?

Despite enormous progress in the treatment of many malignancies, the development of cancer resistance is still an important reason for cancer chemotherapy failure. Increasing knowledge of cancers' molecular complexity and mechanisms of their resistance to anticancer drugs, as well as extensive clinical experience, indicate that an effective fight against cancer requires a multidimensional approach. Multi-target chemotherapy may be achieved using drugs combination, co-delivery of medicines, or designing hybrid drugs. Hybrid drugs simultaneously targeting many points of signaling networks and various structures within a cancer cell have been extensively explored in recent years. The single hybrid agent can modulate multiple targets involved in cancer cell proliferation, possesses a simpler pharmacokinetic profile to reduce the possibility of drug interactions occurrence, and facilitates the process of drug development. Moreover, a single medication is expected to enhance patient compliance due to a less complicated treatment regimen, as well as a diminished number of adverse reactions and toxicity in comparison to a combination of drugs. As a consequence, many efforts have been made to design hybrid molecules of different chemical structures and functions as a means to circumvent drug resistance. The enormous number of studies in this field encouraged us to review the available literature and present selected research results highlighting the possible role of hybrid drugs in overcoming cancer drug resistance.

Effects of melatonin on the toxicity and proliferation of human anaplastic thyroid cancer cell line

BACKGROUND

Thyroid carcinoma is the most common endocrine malignancy and anaplastic thyroid carcinoma (ATC) is a rare but most aggressive cancer. Melatonin has enhanced or induced apoptosis in many different cancer cells, however, there has not been any study on the effects of melatonin in the treatment of ATC. In this study, we examined the effect of melatonin on cytotoxicity in the human ATC cell line.

MATERIALS AND METHODS

Cultured ATC cells were treated at melatonin concentrations 0.6, 1, 4, 16, 28 mM for 24 h. The MTT assay was performed to examine cell viability. Cytotoxicity was assayed with the determination of lactic dehydrogenase (LDH) activity. Apoptosis was detected by acridine orange/ethidium bromide and Hoechst 33342 staining. Giemsa staining is considered for evaluating the morphological changes of ATC cells. The reproductive ability of cells to form a colony was evaluated by the clonogenic assay.

RESULTS

Results showed that melatonin could significantly decrease cell viability and the lowest cell viability was observed at 28 mM, 10.26 % ± 0.858 versus control. Similar results were obtained when analyzing LDH activity. The highest LDH levels were observed at 16 and 28 mM (546.08 ± 4.66, 577.82 ± 3.14 munit/mL versus control) that confirmed the occurrence of late apoptosis. The clonogenic assay showed that cells at the high concentration of melatonin (16 and 28 mM) don't enable to form the colony that approved the occurrence of reproductive death.

CONCLUSION

Our results showed a dose-dependent cytotoxic effect of melatonin on ATC cells that significantly decreased cell viability and induced cell reproductive death at the concentration greater than 1 mM and findings suggested that MLT might be useful as an adjuvant in ATC therapy.

Synergistic Effects of Lenvatinib (E7080) and MEK Inhibitors against Anaplastic Thyroid Cancer in Preclinical Models

E7080, known as lenvatinib, is an oral multitargeted tyrosine kinase inhibitor that has been shown to improve the survival rate of patients with radioiodine-refractory thyroid cancer. However, a majority of patients do not continue lenvatinib intake due to disease progression or significant toxicity. To improve treatment success rates, we propose the combination of lenvatinib with mitogen-activated protein kinase (MEK) inhibitors. To test this hypothesis, we tested the effects of lenvatinib with the MEK inhibitor U0126 in vitro using two human anaplastic thyroid cancer (ATC) cell lines, 8505C and TCO1, and with another MEK inhibitor, selumetinib (AZD6244), in an ATC mouse model. We found that the combination of lenvatinib with MEK inhibitors enhanced the antitumor effects of monotherapy with either agent in vitro and in vivo, and these effects may be through the AKT (Protein Kinase B) and extracellular signal-regulated kinase (ERK) signaling pathways. Furthermore, the combination does not have significant adverse effects in the ATC mouse models in terms of body weight, blood biochemical parameters, and histopathology. In conclusion, the combination of lenvatinib with an MEK inhibitor is a potentially viable therapeutic approach for ATC treatment.

Anticancer Therapy with HDAC Inhibitors: Mechanism-Based Combination Strategies and Future Perspectives

The increasing knowledge of molecular drivers of tumorigenesis has fueled targeted cancer therapies based on specific inhibitors. Beyond "classic" oncogene inhibitors, epigenetic therapy is an emerging field. Epigenetic alterations can occur at any time during cancer progression, altering the structure of the chromatin, the accessibility for transcription factors and thus the transcription of genes. They rely on post-translational histone modifications, particularly the acetylation of histone lysine residues, and are determined by the inverse action of histone acetyltransferases (HATs) and histone deacetylases (HDACs). Importantly, HDACs are often aberrantly overexpressed, predominantly leading to the transcriptional repression of tumor suppressor genes. Thus, histone deacetylase inhibitors (HDACis) are powerful drugs, with some already approved for certain hematological cancers. Albeit HDACis show activity in solid tumors as well, further refinement and the development of novel drugs are needed. This review describes the capability of HDACis to influence various pathways and, based on this knowledge, gives a comprehensive overview of various preclinical and clinical studies on solid tumors. A particular focus is placed on strategies for achieving higher efficacy by combination therapies, including phosphoinositide 3-kinase (PI3K)-EGFR inhibitors and hormone- or immunotherapy. This also includes new bifunctional inhibitors as well as novel approaches for HDAC degradation via PROteolysis-TArgeting Chimeras (PROTACs).

Design, synthesis and evaluation of novel ErbB/HDAC multitargeted inhibitors with selectivity in EGFRT790M mutant cell lines

Acquired resistance leads to the failure of EGFR TKIs in NSCLC treatment. A novel series of hydroxamic acid-containing 4-aminoquinazoline derivatives as irreversible ErbB/HDAC multitargeted inhibitors for NSCLC therapy had been designed and synthesized, which displayed weak anti-proliferative activity in several EGFR wild-type cancer cell lines (NCI-H838, SK-BR-3, A549, A431) yet retained moderate activity to EGFR^T790M resistance mutation harboring NCI-H1975 cells. The mechanistic studies revealed that the representative compound 11e was able to inhibit the phosphorylation of EGFR, up-regulate hyperacetylation of histone H3 and even reduce the expression of EGFR and Akt in NCI-H1975 cells. In further assays, compound 11e also showed moderate anti-proliferative activity in other EGFR^T790M harboring tumor cell lines (NCI-H820, Ba/F3_EGFR_Del19-T790M-C797S) and low toxicities in normal cell lines (HL-7702, FHC). This selectivity of designed multitargeted compounds could serve as a potential strategy to circumvent multiple mechanisms of acquired resistance to EGFR-targeted therapy without severe toxicities and side effects resulting from broad inhibition.

Anticancer properties of chimeric HDAC and kinase inhibitors

Histone deacetylases (HDACs) are epigenetic regulators of chromatin condensation and decondensation and exert effects on the proliferation and spread of cancer. Thus, HDAC enzymes are promising drug targets for the treatment of cancer. Some HDAC inhibitors such as the hydroxamic acid derivatives vorinostat or panobinostat were already approved for the treatment of hematologic cancer diseases, and are under intensive investigation for their use in solid tumors. But there are also drawbacks of the clinical application of HDAC inhibitors like intrinsic or acquired drug resistance and, thus, new HDAC inhibitors with improved activities are sought for. Kinase inhibitors are very promising anticancer drugs and often showed synergistic anticancer effects in combination with HDAC inhibitors. Several hybrid molecules with HDAC and kinase inhibitory structural motifs were disclosed with even improved anticancer activities when compared with co-application of HDAC and receptor tyrosine kinase inhibitors. Chimeric inhibitors with HDAC inhibitory activities exert a rapidly growing field of research and only in this year several new dual HDAC/kinase inhibitors were disclosed. This review briefly summarizes the status and future perspective of the most advanced and promising dual HDAC/kinase inhibitors and their potential as anticancer drug candidates.

Synergistic Enhancement of Cancer Therapy Using HDAC Inhibitors: Opportunity for Clinical Trials

Chemotherapy is one of the most established and effective treatments for almost all types of cancer. However, the elevated toxicity due to the non-tumor-associated effects, development of secondary malignancies, infertility, radiation-induced fibrosis and resistance to treatment limit the effectiveness and safety of treatment. In addition, these multiple factors significantly impact quality of life. Over the last decades, our increased understanding of cancer epigenetics has led to new therapeutic approaches and the promise of improved patient outcomes. Epigenetic alterations are commonly found in cancer, especially the increased expression and activity of histone deacetylases (HDACs). Dysregulation of HDACs are critical to the development and progression of the majority of tumors. Hence, HDACs inhibitors (HDACis) were developed and now represent a very promising treatment strategy. The use of HDACis as monotherapy has shown very positive pre-clinical results, but clinical trials have had only limited success. However, combinatorial regimens with other cancer drugs have shown synergistic effects both in pre-clinical and clinical studies. At the same time, these combinations have enhanced the efficacy, reduced the toxicity and tumor resistance to therapy. In this review, we will examine examples of HDACis used in combination with other cancer drugs and highlight the synergistic effects observed in recent preclinical and clinical studies.

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.

Primary cell cultures for the personalized therapy in aggressive thyroid cancer of follicular origin

Thyroid cancer (TC) is the most prevalent endocrine malignancy. More than 90 % of TC is represented by differentiated TC (DTC) arising from the follicular thyroid cells. DTC includes papillary TC (PTC), follicular TC (FTC), and Hürthle cell TC. Anaplastic TC (ATC) accounts for 1% of TC, and it represents 15-40 % of TC death. Current treatment strategies are not completely effective against aggressive DTC or ATC, and mortality is one of the most important challenges. Recently, progresses have been obtained in the understanding of the molecular/genetic basis of TC progression, and new drugs have been introduced [i.e. tyrosine kinase inhibitors (TKIs)], able to block the oncogenic or signaling kinases, associated with cellular growth. Thyroid cell lines, obtained from tumoral cells and chosen for high proliferation in vitro, have been used as preclinical models. Actually, these cells lose the characteristic features of the primary tumor, because they adapt to in vitro growth conditions. For these reasons, the use of these cell lines has important limitations, and more recently human primary cell cultures have been established as monolayer cultures, and investigated for their biological behavior. Moreover, in the past, primary TC cells could be collected only through surgical biopsies, while recently human primary cell cultures can be established also from samples of fine-needle aspiration citology from aggressive dedifferentiated DTC or ATC. Testing in vitro different TKIs in each patient can help to develop new personalized treatments, without using ineffective drugs. In conclusion, personalized medicine and precise oncology, which consider both patients and their disease features, represent the future of the treatment approach, and further progress is needed in this direction.

TGFα Promotes Chemoresistance of Malignant Pleural Mesothelioma

Background: There is no standard chemotherapy for refractory or relapsing malignant pleural mesothelioma (MPM). Our previous reports nevertheless indicated that a combination of an anthracycline (doxorubicin) and a lysine deacetylase inhibitor (valproic acid, VPA) synergize to induce the apoptosis of MPM cells and reduce tumor growth in mouse models. A Phase I/II clinical trial indicated that this regimen is a promising therapeutic option for a proportion of MPM patients. Methods: The transcriptomes of mesothelioma cells were compared after Illumina HiSeq 4000 sequencing. The expression of differentially expressed genes was inhibited by RNA interference. Apoptosis was determined by cell cycle analysis and Annexin V/7-AAD labeling. Protein expression was assessed by immunoblotting. Preclinical efficacy was evaluated in BALB/c and NOD-SCID mice. Results: To understand the mechanisms involved in chemoresistance, the transcriptomes of two MPM cell lines displaying different responses to VPA-doxorubicin were compared. Among the differentially expressed genes, transforming growth factor alpha (TGFα) was associated with resistance to this regimen. The silencing of TGFα by RNA interference correlated with a significant increase in apoptosis, whereas the overexpression of TGFα desensitized MPM cells to the apoptosis induced by VPA and doxorubicin. The multi-targeted inhibition of histone deacetylase (HDAC), HER2 and TGFα receptor (epidermal growth factor receptor/EGFR) improved treatment efficacy in vitro and reduced tumor growth in two MPM mouse models. Finally, TGFα expression but not EGFR correlated with patient survival. Conclusions: Our data show that TGFα but not its receptor EGFR is a key factor in resistance to MPM chemotherapy. This observation may contribute to casting light on the promising but still controversial role of EGFR signaling in MPM therapy.

Amino Acid Transporters as Potential Therapeutic Targets in Thyroid Cancer

Thyroid cancer cells have a high amino acid demand for proliferation, invasion, and metastasis. Amino acids are taken up by thyroid cancer cells, both thyroid follicular cell and thyroid parafollicular cells (commonly called "C-cells"), via amino acid transporters. Amino acid transporters up-regulate in many cancers, and their expression level associate with clinical aggressiveness and prognosis. This is the review to discuss the therapeutic potential of amino acid transporters and as molecular targets in thyroid cancer.

A Combinatorial Strategy for Targeting BRAF V600E-Mutant Cancers with BRAFV600E Inhibitor (PLX4720) and Tyrosine Kinase Inhibitor (Ponatinib)

PURPOSE

Most aggressive thyroid cancers are commonly associated with a BRAF ^V600E mutation. Preclinical and clinical data in BRAF ^V600E cancers suggest that combined BRAF and MEK inhibitor treatment results in a response, but resistance is common. One mechanism of acquired resistance is through persistent activation of tyrosine kinase (TK) signaling by alternate pathways. We hypothesized that combination therapy with BRAF and multitargeting TK inhibitors (MTKI) might be more effective in BRAF ^V600E thyroid cancer than in single-agent or BRAF and MEK inhibitors.

EXPERIMENTAL DESIGN

The combined drug activity was analyzed to predict any synergistic effect using high-throughput screening (HTS) of active drugs. We performed follow-up in vitro and in vivo studies to validate and determine the mechanism of action of synergistic drugs.

RESULTS

The MTKI ponatinib and the BRAF inhibitor PLX4720 showed synergistic activity by HTS. This combination significantly inhibited proliferation, colony formation, invasion, and migration in BRAF ^V600E thyroid cancer cell lines and downregulated pERK/MEK and c-JUN signaling pathways, and increased apoptosis. PLX4720-resistant BRAF ^V600E cells became sensitized to the combination treatment, with decreased proliferation at lower PLX4720 concentrations. In an orthotopic thyroid cancer mouse model, combination therapy significantly reduced tumor growth (P < 0.05), decreased the number of metastases (P < 0.05), and increased survival (P < 0.05) compared with monotherapy and vehicle control.

CONCLUSIONS

Combination treatment with ponatinib and PLX4720 exhibited significant synergistic anticancer activity in preclinical models of BRAF ^V600E thyroid cancer, in addition to overcoming PLX4720 resistance. Our results suggest this combination should be tested in clinical trials.

Novel treatments for anaplastic thyroid carcinoma

Anaplastic thyroid cancer (ATC) is one of the deadliest human cancers and it is less than 2% of thyroid carcinomas (TCs). The standard treatment of ATC includes surgical debulking, accelerated hyperfractionated external beam radiation therapy (EBRT), and chemotherapy, in particular with cisplatin or doxorubicin, achieving about 10 months of median survival. Since ATC is a rare and aggressive tumor, it is still challenging to predict the patient clinical therapy responsiveness. Several genetic mutations have been described in ATC, involved in different molecular pathways linked to tumor progression, and novel therapies acting on these molecular pathways have been investigated, to improve the quality of life in these patients. Here we review the new targeted therapy of ATC. We report interesting results obtained with molecules targeting different pathways: angiogenesis (vandetanib, combretastatin, sorafenib, lenvatinib, sunitinib, CLM94, CLM3, etc.); EGFR (gefitinib, docetaxel); BRAF (dabrafenib/trametinib, vemurafenib); PPARγ agonists (rosiglitazone, pioglitazone, efatutazone); PD-1 and PD-L1 (pembrolizumab); TERT. To escape resistance to monotherapies, the evaluation of combination strategies with radiotherapy, chemotherapy, or targeted drugs is ongoing. The results of clinical trials with dabrafenib and trametinib led to the approval from FDA of this combination for patients with BRAF V600E mutated ATC with locally advanced, unresectable, or metastatic ATC. The anti-PD-L1 antibody immunotherapy, alone or combined with a BRAF inhibitor, has been shown also promising in the treatment of ATC. Furthermore, to increase the therapeutic success and not to use ineffective or even harmful treatments, a real tailored therapy should be pursued, and this can be achieved thanks to the new available genomic analysis methods and to the possibility to test in vitro novel treatments directly in primary cells from each ATC patient. Exploring new treatment strategies is mandatory to improve the survival of these patients, guaranteeing a good quality of life.

Epigenetic polypharmacology: A new frontier for epi-drug discovery

Recently, despite the great success achieved by the so-called "magic bullets" in the treatment of different diseases through a marked and specific interaction with the target of interest, the pharmacological research is moving toward the development of "molecular network active compounds," embracing the related polypharmacology approach. This strategy was born to overcome the main limitations of the single target therapy leading to a superior therapeutic effect, a decrease of adverse reactions, and a reduction of potential mechanism(s) of drug resistance caused by robustness and redundancy of biological pathways. It has become clear that multifactorial diseases such as cancer, neurological, and inflammatory disorders, may require more complex therapeutic approaches hitting a certain biological system as a whole. Concerning epigenetics, the goal of the multi-epi-target approach consists in the development of small molecules able to simultaneously and (often) reversibly bind different specific epi-targets. To date, two dual histone deacetylase/kinase inhibitors (CUDC-101 and CUDC-907) are in an advanced stage of clinical trials. In the last years, the growing interest in polypharmacology encouraged the publication of high-quality reviews on combination therapy and hybrid molecules. Hence, to update the state-of-the-art of these therapeutic approaches avoiding redundancy, herein we focused only on multiple medication therapies and multitargeting compounds exploiting epigenetic plus nonepigenetic drugs reported in the literature in 2018. In addition, all the multi-epi-target inhibitors known in literature so far, hitting two or more epigenetic targets, have been included.

HER2-targeted multimodal imaging of anaplastic thyroid cancer

Clinical management of anaplastic thyroid cancer (ATC) is very challenging due to its dedifferentiation and aggressiveness. We aim to develop HER2-targeted multimodal imaging approaches and assess the diagnostic efficacies of these molecular imaging probes in preclinical ATC models. Flow cytometry was used to detect HER2 expression status in thyroid cancer cell lines. We then developed a HER2-specific immunoPET imaging probe ⁸⁹Zr-Df-pertuzumab by radiolabeling a HER-2 specific monoclonal antibody (mAb) pertuzumab with ⁸⁹Zr (t_1/2=78.4 h) and a fluorescent imaging probe IRDye 800CW-pertuzumab. The diagnostic efficacies of the probes were assessed in subcutaneous and orthotopic ATC models, followed by ex vivo biodistribution profile and immunofluorescence staining studies. HER2 was highly expressed on the surface of all the four primary thyroid cancer cell lines examined, which included two ATC cell lines (i.e., 8505C and THJ-16T). PET imaging with ⁸⁹Zr-Df-pertuzumab clearly visualized all the subcutaneous ATCs with a peak tumor uptake of 20.23±6.44 %ID/g (n=3), whereas the highest tumor uptake of the nonspecific probe ⁸⁹Zr-Df-IgG in subcutaneous ATC models was 6.30±0.95 %ID/g (n=3). More importantly, ⁸⁹Zr-Df-pertuzumab PET imaging strategy readily delineated all the orthotopic ATCs with a peak tumor uptake of 24.93±8.53 %ID/g (n=3). We also suggested that Cerenkov luminescence imaging (CLI) using ⁸⁹Zr-Df-pertuzumab and fluorescence imaging using IRDye 800CW-pertuzumab are useful tools for image-guided removal of ATCs. We demonstrate that HER2 is a promising biomarker for ATC, and multimodal imaging using ⁸⁹Zr-Df-pertuzumab and IRDye 800CW-pertuzumab is useful for identifying HER2-postive ATCs.

A novel therapeutic approach for anaplastic thyroid cancer through inhibition of LAT1

A novel therapeutic approach is urgently needed for patients with anaplastic thyroid cancer (ATC) due to its fatal and rapid progress. We recently reported that ATC highly expressed MYC protein and blocking of MYC through its selective inhibitor, JQ1, decreased ATC growth and improved survival in preclinical models. One of the important roles of MYC is regulation of L-neutral amino acid transporter 1 (LAT1) protein and inhibition of LAT1 would provide similar anti-tumor effect. We first identified that while the human ATC expresses LAT1 protein, it is little or not detected in non-cancerous thyroidal tissue, further supporting LAT1 as a good target. Then we evaluated the efficacy of JPH203, a LAT1 inhibitor, against ATC by using the in vitro cell-based studies and in vivo xenograft model bearing human ATC cells. JPH203 markedly inhibited proliferation of three ATC cell lines through suppression of mTOR signals and blocked cell cycle progression from the G0/G1 phase to the S phase. The tumor growth inhibition and decrease in size by JPH203 via inhibition of mTOR signaling and G0/G1 cell cycle associated proteins were further confirmed in xenograft models. These preclinical findings suggest that LAT1 inhibitors are strong candidates to control ATC, for which current treatment options are highly limited.

Mouse models of thyroid cancer: Bridging pathogenesis and novel therapeutics

Due to a global increase in the incidence of thyroid cancer, numerous novel mouse models were established to reveal thyroid cancer pathogenesis and test promising therapeutic strategies, necessitating a comprehensive review of translational medicine that covers (i) the role of mouse models in the research of thyroid cancer pathogenesis, and (ii) preclinical testing of potential anti-thyroid cancer therapeutics. The present review article aims to: (i) describe the current approaches for mouse modeling of thyroid cancer, (ii) provide insight into the biology and genetics of thyroid cancers, and (iii) offer guidance on the use of mouse models for testing potential therapeutics in preclinical settings. Based on research with mouse models of thyroid cancer pathogenesis involving the RTK, RAS/RAF/MEK/ERK, PI3K/AKT/mTOR, SRC, and JAK-STAT signaling pathways, inhibitors of VEGFR, MEK, mTOR, SRC, and STAT3 have been developed as anti-thyroid cancer drugs for "bench-to-bedside" translation. In the future, mouse models of thyroid cancer will be designed to be ''humanized" and "patient-like," offering opportunities to: (i) investigate the pathogenesis of thyroid cancer through target screening based on the CRISPR/Cas system, (ii) test drugs based on new mouse models, and (iii) explore the underlying mechanisms based on multi-omics.

REGγ potentiates TGF-β/Smad signal dependent epithelial-mesenchymal transition in thyroid cancer cells

Thyroid cancer is the most common endocrine cancer with an increasing incidence and mortality. Epithelial-mesenchymal transition (EMT) is a biological process contributing to tumor progression, metastasis, and the acquisition of chemotherapy resistance. The impact of the REGγ proteasome activator on EMT in human thyroid cancer cells and the molecular mechanism is still unclear. Here, we found silencing REGγ in thyroid cancer cells inhibited cell migration and invasion, with concurrent upregulation of E-cadherin and Smurf2 expression. Mechanistically, REGγ dependent regulation of Smurf2, an E3 ligase for Smad3, contributed to alteration of Zeb1/2, Snail, Slug, and Twist. Consistently, TGF-β mediated suppression of E-cadherin was attenuated in REGγ deficient cells, coupled with changes in cell morphology, migration and invasion. Furthermore, xenograft metastasis mouse model showed a reduced E-cadherin expression at both mRNA and protein levels, and decreased cell migration. Taken together, our findings provided an important evidence for the role of REGγ in tumor suppression, thereby implicating REGγ as a potential anti-cancer strategy in thyroid cancer therapy.

Diagnosis and Management of Anaplastic Thyroid Cancer

Anaplastic thyroid cancer (ATC) is a devastating and usually incurable diagnosis. Clinical and pathologic diagnosis is best assessed at a tertiary center with concentrated ATC expertise. Expeditious multidisciplinary management is recommended for optimal patient outcomes. Based on multiinstitutional and population-based studies, multimodal therapy that includes chemoradiotherapy with surgery (when feasible) is the preferred initial treatment because it is associated with incrementally improved overall survival. In ATC that carries a BRAF V600E somatic mutation, combination therapy with BRAF and MEK inhibitors has shown promise but needs further study. Immunotherapeutic agents in neoadjuvant and metastatic settings are being investigated.

Low intensity focused ultrasound (LIFU) triggered drug release from cetuximab-conjugated phase-changeable nanoparticles for precision theranostics against anaplastic thyroid carcinoma

This study provides an efficient theranostic strategy for concurrent targeted ultrasound molecular imaging and effective synergistic antitumor therapy.

Lysyl Oxidase Is a Key Player in BRAF/MAPK Pathway-Driven Thyroid Cancer Aggressiveness

BACKGROUND

The BRAF^V600E mutation is the most common somatic mutation in thyroid cancer. The mechanism associated with BRAF-mutant tumor aggressiveness remains unclear. Lysyl oxidase (LOX) is highly expressed in aggressive thyroid cancers, and involved in cancer metastasis. The objective was to determine whether LOX mediates the effect of the activated MAPK pathway in thyroid cancer.

METHODS

The prognostic value of LOX and its association with mutated BRAF was analyzed in The Cancer Genome Atlas and an independent cohort. Inhibition of mutant BRAF and the MAPK pathway, and overexpression of mutant BRAF and mouse models of BRAF^V600E were used to test the effect on LOX expression.

RESULTS

In The Cancer Genome Atlas cohort, LOX expression was higher in BRAF-mutant tumors compared to wild-type tumors (p < 0.0001). Patients with BRAF-mutant tumors with high LOX expression had a shorter disease-free survival (p = 0.03) compared to patients with a BRAF mutation and the low LOX group. In the independent cohort, a significant positive correlation between LOX and percentage of BRAF mutated cells was found. The independent cohort confirmed high LOX expression to be associated with a shorter disease-free survival (p = 0.01). Inhibition of BRAF^V600E and MEK decreased LOX expression. Conversely, overexpression of mutant BRAF increased LOX expression. The mice with thyroid-specific expression of BRAF^V600E showed strong LOX and p-ERK expression in tumor tissue. Inhibition of BRAF^V600E in transgenic and orthotopic mouse models significantly reduced the tumor burden as well as LOX and p-ERK expression.

CONCLUSIONS

The data suggest that BRAF^V600E tumors with high LOX expression are associated with more aggressive disease. The biological underpinnings of the clinical findings were confirmed by showing that BRAF and the MAPK pathway regulate LOX expression.

Antitumor activity of the novel HDAC inhibitor CUDC-101 combined with gemcitabine in pancreatic cancer

Histone deacetylase (HDAC) is overexpressed in multiple cancers including pancreatic cancer (PC). However, the effects of histone deacetylase inhibitor (HDACi) on apoptosis and epithelial-mesenchymal transition (EMT) differ in various cancers. In this study, we aimed to investigate the anti-tumor effects of a novel multitargets HDACi, CUDC-101, combined with gemcitabine in PC cell lines. In vitro, we found that Co-treatment with CUDC-101 and gemcitabine results in greater levels of apoptosis and significantly inhibited cell proliferation on PC cells. In addition, CUDC-101 enhanced gemcitabine-induced apoptosis via inhibited PI3K/Akt/mTOR and Erk pathway activation, as indicated by the phosphorylation status of Akt, 4EBP1, S6 and Erk. We also found that co-treatment with gemcitabine and CUDC-101 not only synergistically suppressed ability of PC cell migration and invasion, but also synergistically inhibited EMT signaling pathway through modulation of cadherin, vimentin and transcription factors Snail, Slug and MMP-9. In vivo, the co-treatment group showed a significant anti-tumor function in the growth of xenograft tumors. Overall, combination of CUDC-101 and gemcitabine significantly increased anti-tumor activities compared with single drug alone, thus supporting a further evaluation of combination treatment for PC. Accordingly, it provides a rationale to investigate the combination of gemcitabine and CUDC-101 as a potential therapeutic strategy for PC.

Therapeutic advances in anaplastic thyroid cancer: a current perspective

Thyroid cancer incidence is increasing at an alarming rate, almost tripling every decade. In 2017, it was the fifth most common cancer in women. Although the majority of thyroid tumors are curable, about 2-3% of thyroid cancers are refractory to standard treatments. These undifferentiated, highly aggressive and mostly chemo-resistant tumors are phenotypically-termed anaplastic thyroid cancer (ATC). ATCs are resistant to standard therapies and are extremely difficult to manage. In this review, we provide the information related to current and recently emerged first-line systemic therapy (Dabrafenib and Trametinib) along with promising therapeutics which are in clinical trials and may be incorporated into clinical practice in the future. Different categories of promising therapeutics such as Aurora kinase inhibitors, multi-kinase inhibitors, epigenetic modulators, gene therapy using oncolytic viruses, apoptosis-inducing agents, and immunotherapy are reviewed. Combination treatment options that showed synergistic and antagonistic effects are also discussed. We highlight ongoing clinical trials in ATC and discuss how personalized medicine is crucial to design the second line of treatment. Besides using conventional combination therapy, embracing a personalized approach based on advanced genomics and proteomics assessment will be crucial to developing a tailored treatment plan to improve the chances of clinical success.

Targeting post-translational histone modifications for the treatment of non-medullary thyroid cancer

Genomic and epigenetic alterations are now being exploited as molecular targets in cancer treatment. Abnormalities involving the post-translational modification of histones have been demonstrated in thyroid cancer, and they are regarded as promising molecular targets for novel drug treatment of tumors that are resistant to conventional therapies. After a brief overview of the histone modifications most commonly associated with human malignancies, we will review recently published preclinical and clinical findings regarding the use of histone-activity modulators in thyroid cancers. Particular attention will be focused on their use as re-differentiating or anti-proliferating agents, the differential effects observed when they are used alone and in combination with other targeted drugs, and current prospects for their use in the treatment of thyroid cancer.

High-throughput drug library screening identifies colchicine as a thyroid cancer inhibitor

We employed a high-throughput drug library screening platform to identify novel agents affecting thyroid cancer cells. We used human thyroid cancer cell lines to screen a collection of approximately 5200 small molecules with biological and/or pharmacologial properties. Parallel primary screens yielded a number of hits differentially active between thyroid and melanoma cells. Amongst compounds specifically targeting thyroid cancer cells, colchicine emerged as an effective candidate. Colchicine inhibited cell growth which correlated with G2 cell cycle arrest and apoptosis. These effects were hampered through inhibition of MEK1/2 and JNK. In contrast, inhibition of p38-MAPK had little effect, and AKT had no impact on colchicine action. Systemic colchicine inhibited thyroid cancer progression in xenografted mice. These findings demonstrate that our screening platform is an effective vehicle for drug reposition and show that colchicine warrants further attention in well-defined clinical niches such as thyroid cancer.

Long noncoding RNA NEAT1 promotes the metastasis of osteosarcoma via interaction with the G9a-DNMT1-Snail complex

Osteosarcoma (OS) is the most common histological form of primary bone cancer. Long noncoding RNA nuclear enriched abundant transcript 1 (NEAT1) functions as an oncogene in some cancers. However, the functional role of NEAT1 in OS metastasis remains elusive. In the present study, we found that NEAT1 expression was significantly increased in OS tissues and cell lines. Overexpression of NEAT1 in OS tissues was correlated with higher clinical stage, distant metastasis and poorer prognosis. Loss- and gain-of-function assays showed that NEAT1 positively regulated metastasis in vitro and in vivo. In addition, ectopic expression of NEAT1 also induced epithelial-mesenchymal transition (EMT). Mechanistic studies revealed that NEAT1 epigenetically suppresses E-cadherin expression through association with G9a-DNMT1-Snail complex. Taken together, our study reveals a critical epigenetic mechanism underlying NEAT1-mediated metastasis.

Histone deacetylase 6 (HDAC6) deacetylates extracellular signal-regulated kinase 1 (ERK1) and thereby stimulates ERK1 activity

Histone deacetylase 6 (HDAC6), a class IIb HDAC, plays an important role in many biological and pathological processes. Previously, we found that ERK1, a downstream kinase in the mitogen-activated protein kinase signaling pathway, phosphorylates HDAC6, thereby increasing HDAC6-mediated deacetylation of α-tubulin. However, whether HDAC6 reciprocally modulates ERK1 activity is unknown. Here, we report that both ERK1 and -2 are acetylated and that HDAC6 promotes ERK1 activity via deacetylation. Briefly, we found that both ERK1 and -2 physically interact with HDAC6. Endogenous ERK1/2 acetylation levels increased upon treatment with a pan-HDAC inhibitor, an HDAC6-specific inhibitor, or depletion of HDAC6, suggesting that HDAC6 deacetylates ERK1/2. We also noted that the acetyltransferases CREB-binding protein and p300 both can acetylate ERK1/2. Acetylated ERK1 exhibits reduced enzymatic activity toward the transcription factor ELK1, a well-known ERK1 substrate. Furthermore, mass spectrometry analysis indicated Lys-72 as an acetylation site in the ERK1 N terminus, adjacent to Lys-71, which binds to ATP, suggesting that acetylation status of Lys-72 may affect ERK1 ATP binding. Interestingly, an acetylation-mimicking ERK1 mutant (K72Q) exhibited less phosphorylation than the WT enzyme and a deacetylation-mimicking mutant (K72R). Of note, the K72Q mutant displayed decreased enzymatic activity in an in vitro kinase assay and in a cellular luciferase assay compared with the WT and K72R mutant. Taken together, our findings suggest that HDAC6 stimulates ERK1 activity. Along with our previous report that ERK1 promotes HDAC6 activity, we propose that HDAC6 and ERK1 may form a positive feed-forward loop, which might play a role in cancer.

Carfilzomib potentiates CUDC-101-induced apoptosis in anaplastic thyroid cancer

Anaplastic thyroid cancer (ATC) is one of the most aggressive human malignancies, with no effective treatment currently available. Previously, we identified agents active against ATC cells, both in vitro and in vivo, using quantitative high-throughput screening of 3282 clinically approved drugs and small molecules. Here, we report that combining two of these active agents, carfilzomib, a second-generation proteasome inhibitor, and CUDC-101, a histone deacetylase and multi-kinase inhibitor, results in increased, synergistic activity in ATC cells. The combination of carfilzomib and CUDC-101 synergistically inhibited cellular proliferation and caused cell death in multiple ATC cell lines harboring various driver mutations observed in human ATC tumors. This increased anti-ATC effect was associated with a synergistically enhanced G2/M cell cycle arrest and increased caspase 3/7 activity induced by the drug combination. Mechanistically, treatment with carfilzomib and CUDC-101 increased p21 expression and poly (ADP-ribose) polymerase protein cleavage. Our results suggest that combining carfilzomib and CUDC-101 would offer an effective therapeutic strategy to treat ATC.

Novel treatment options for anaplastic thyroid cancer

Several genetic alterations have been identified in different molecular pathways ofanaplastic thyroid cancer (ATC) and associated with tumor aggressiveness and progression (BRAF, p53,RAS, EGFR, VEGFR-1, VEGFR-2, etc). New drugs targeting these molecular pathways have beenrecently evaluated in ATC. Areas covered: We review the new targeted therapies of ATC. Interesting results have been reported with molecules targeting different pathways, as: a-BRAF (dabrafenib/trametinib, vemurafenib); b-angiogenesis (sorafenib, combretastatin, vandetanib, sunitinib, lenvatinib, CLM3, etc); c-EGFR (gefitinib); d- PPARγ agonists (rosiglitazone, pioglitazone, efatutazone). In patients with ATC treated with lenvatinib, a median overall survival of 10.6 (3.8-19.8) months was reported. In order to bypass the resistance to the single drug, the capability of targeted drugs to synergize with radiation, or chemotherapy, or other targeted drugs is explored. Expert commentary: New, affordable and individual genomic analysis combined with the opportunity to test these new treatments in primary cell cultures from every ATC patient in vitro, may permit the personalization of therapy. Increasing the therapeutic effectiveness and avoiding the use of ineffective drugs. The identification of new treatments is necessary, to extend life duration guaranteing a good quality of life. To bypass the resistance to asingle drug, the capability of targeted drugs to synergize with radiation, or chemotherapy, or othertargeted drugs is explored. Moreover, new affordable individual genomic analysis and the opportunity totest these novel treatments in primary cell cultures from every ATC patient in vitro, might permit topersonalize the therapy, increasing the therapeutic effectiveness and avoiding the use of ineffectivedrugs.

Lowered levels of microRNA-129 and potential signaling pathways in papillary thyroid carcinoma: a determination of microRNA sequencing in 507 patients and bioinformatics analysis

Papillary thyroid carcinoma (PTC) is one of the most common endocrine system malignancies. However, the mechanism of tumor development is unclear. microRNA-129-5p is a microRNA that plays an important role in the development of tumors. The main purpose of our article is to find the potential target genes of microRNA-129 and their pathways based on gene array, sequencing and bioinformatics studies. We obtained microRNA-129 expression and clinical associations in the TCGA database. In addition, we found a microRNA-129-related chip GSE19933, which is overexpressing microR-129-5p in thyroid cancer cell lines. The down-regulated gene is considered to be a potential target gene for microRNA-129. The target genes were predicted through 12 online tools. We performed Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis of all down-regulated and predicted target genes. Furthermore, protein-protein interactions (PPI) were also analyzed for all potential genes. Finally, with intersecting down-regulated genes by overexpressed microRNA-129 and predicted target genes, the 889 genes are mainly enriched in the calcium signaling pathway, cGMP-PKG signaling pathway, ErbB signaling pathway and Proteoglycans in cancer, etc. The role of ten hub genes is particularly prominent in PPI analysis. These genes are differentially expressed in the thyroid by immunohistochemistry. We confirmed that microRNA-129 may play a major role in PTC through the above pathways, but more experiments are still needed to prove our results.

HDAC inhibitors suppress c-Jun/Fra-1-mediated proliferation through transcriptionally downregulating MKK7 and Raf1 in neuroblastoma cells

Activator protein 1 (AP-1) is a transcriptional factor composed of the dimeric members of bZIP proteins, which are frequently deregulated in human cancer cells. In this study, we aimed to identify an oncogenic AP-1 dimer critical for the proliferation of neuroblastoma cells and to investigate whether histone deacetylase inhibitors (HDACIs), a new generation of anticancer agents, could target the AP-1 dimer. We report here that HDACIs including trichostatin A, suberoylanilidehydroxamic acid, valproic acid and M344 can transcriptionally suppress both c-Jun and Fra-1, preceding their inhibition of cell growth. c-Jun preferentially interacting with Fra-1 as a heterodimer is responsible for AP-1 activity and critical for cell growth. Mechanistically, HDACIs suppress Fra-1 expression through transcriptionally downregulating Raf1 and subsequently decreasing MEK1/2-ERK1/2 activity. Unexpectedly, HDACI treatment caused MKK7 downregulation at both the protein and mRNA levels. Deletion analysis of the 5′-flanking sequence of the MKK7 gene revealed that a major element responsible for the downregulation by HDACI is located at −149 to −3 relative to the transcriptional start site. Knockdown of MKK7 but not MKK4 remarkably decreased JNK/c-Jun activity and proliferation, whereas ectopic MKK7-JNK1 reversed HDACI-induced c-Jun suppression. Furthermore, suppression of both MKK-7/c-Jun and Raf-1/Fra-1 activities was involved in the tumor growth inhibitory effects induced by SAHA in SH-SY5Y xenograft mice. Collectively, these findings demonstrated that c-Jun/Fra-1 dimer is critical for neuroblastoma cell growth and that HDACIs act as effective suppressors of the two oncogenes through transcriptionally downregulating MKK7 and Raf1.

Epigenetic modulators of thyroid cancer

There are some well known factors involved in the etiology of thyroid cancer, including iodine deficiency, radiation exposure at early ages, or some genetic changes. However, epigenetic modulators that may contribute to development of these tumors and be helpful to for both their diagnosis and treatment have recently been discovered. The currently known changes in DNA methylation, histone modifications, and non-coding RNAs in each type of thyroid carcinoma are reviewed here.

HTP Nutraceutical Screening for Histone Deacetylase Inhibitors and Effects of HDACis on Tumor-suppressing miRNAs by Trichostatin A and Grapeseed (Vitis vinifera) in HeLa cells

BACKGROUND/AIM

Aggressive tumor malignancies are a consequence of delayed diagnosis, epigenetic/phenotype changes and chemo-radiation resistance. Histone deacetylases (HDACs) are a major epigenetic regulator of transcriptional repression, which are highly overexpressed in advanced malignancy. While original chemotherapy drugs were modeled after phytochemicals elucidated by botanical screenings, HDAC inhibitors (HDACi) such as apicidin, trichostatin A (TSA) and butyrate were discovered as products of fungus and microbes, in particular, gut microbiota. Therefore, a persistent question remains as to the inherent existence of HDACis in raw undigested dietary plant material. In this study, we conduct a high-throughput (HTP) screening of ~1,600 non-fermented commonly used nutraceuticals (spices, herbs, teas, vegetables, fruits, seeds, rinds etc.) at (<600 μg/ml) and food-based polyphenolics (<240 μg/ml) for evidence of HDAC activity inhibition in nuclear HeLa cell lysates.

MATERIALS AND METHODS

Human HDAC kinetic validation was performed using a standard fluorometric activity assay, followed by an enzymatic-linked immuno-captured ELISA. Both methods were verified using HDACi panel drugs: TSA, apicidin, suberohydroxamic acid, M344, CL-994, valproic acid and sodium phenylbutyrate. The HTP screening was then conducted, followed by a study comparing biological effects of HDACis in HeLa cells, including analysis of whole-transcriptome non-coding RNAs using Affymetrix miRNA 4.1-panel arrays.

RESULTS

The HTP screening results confirmed 44/1600 as potential HDACis to which 31 were further eliminated as false-positives. Methodological challenges/concerns are addressed regarding plant product false-positives that arise from the signal reduction of commercial lysine development reagents. Only 13 HDACis were found having an IC₅₀ under <200 μg/ml: Grapeseed extract (Vitis vinifera), Great burnet root (Sanguisorba Officinalis), Babul (Acacia arabica), Chinese gallnut (Melaphis chinensis), Konaberry extract (Coffea arabica), Uva Ursi (Arctostaphylos uva ursi), Green tea (Camellia sinensis), Meadowsweet (Filipendula ulmaria), Sassafras (Sassafras officinale), Turkey rhubarb (Rheum palmatum), epigallocatechin gallate (EGCG), gossypol and gallic acid. Next, we investigate the biological consequence of HDACi panel drugs in HeLa cells, where the data suggest predominant effects are anti-mitotic rather than cytotoxic. Lastly, differential effects of TSA vs. GSE at sub-lethal concentrations tested on HeLa cells show 6,631 miRNAs expressed in resting cells, 35 significantly up-regulated (TSA) and 81 up-regulated (GSE), with several miRNAs overlapping in the upward direction by both GSE and TSA (e.g. hsa-miR-23b-5p, hsa-miR-27b-5p, hsa-miR-1180-3p, hsa-miR-6880-5p and hsa-mir-943). Using DIANA miRNA online tools, it was determined that GSE and TSA simultaneously cause overexpression of similar miRNAs predicted to destroy the following influential oncogenes: NFkB, NRAS, KRAS, HRAS, MYC, TGFBR1, E2F1, E2F2, BCL21, CDKN1A, CDK6, HIF1a, and VEGFA.

CONCLUSION

The data from this study show that plant- based HDACis are relatively rare, and can elicit a similar pattern to TSA in up-regulating miRNAs involved with tumor suppression of HeLa cervical carcinoma.

Inverse expression of caveolin-1 and EGFR in thyroid cancer patients

Cytological analysis of fine-needle aspiration (FNA) is the first step in evaluation of patients with nodular thyroid disease with the primary goal to exclude thyroid malignancy. Its improvement by combining cytology with molecular markers is still a matter of investigation. In this study, 2 molecular markers were used: caveolin-1 and epidermal growth factor receptor (EGFR), along with the well-established genetic marker BRAF V600E mutation. We set out to determine the expression signatures of EGFR and caveolin-1 in patients with thyroid malignancy as well as to determine their possible association with disease severity. In FNA biopsy samples (n=186), immunocytochemical expression of caveolin-1 and BRAF V600E mutation coincided with malignancy. The patients were sorted according to 3 parameters: final histopathological diagnosis, caveolin-1 expression, and BRAF V600E mutation status before measurement of EGFR mRNA expression. EGFR upregulation was detected in the group of patients with malignant diagnosis, no caveolin-1 expression, and wild-type BRAF. Spearman rank correlation yielded a statistically significant negative correlation of EGFR and caveolin-1. Double immunofluorescence confirmed colocalization and inverse expression of EGFR and caveolin-1. Our data demonstrated that EGFR overexpression is associated with malignancy but not with tumor aggressiveness. Furthermore, high-caveolin-1/low-EGFR cases were associated with an advanced pT status and had a greater degree of neoplastic infiltration than low-caveolin-1/high-EGFR cases. Combining caveolin-1 and BRAF V600E with EGFR might help in recognizing more aggressive thyroid lesions in a pool of relatively indolent tumors in FNA biopsies and thus be useful for early risk stratification of thyroid cancer patients.

HDACs and HDAC Inhibitors in Cancer Development and Therapy

Over the last several decades, it has become clear that epigenetic abnormalities may be one of the hallmarks of cancer. Posttranslational modifications of histones, for example, may play a crucial role in cancer development and progression by modulating gene transcription, chromatin remodeling, and nuclear architecture. Histone acetylation, a well-studied posttranslational histone modification, is controlled by the opposing activities of histone acetyltransferases (HATs) and histone deacetylases (HDACs). By removing acetyl groups, HDACs reverse chromatin acetylation and alter transcription of oncogenes and tumor suppressor genes. In addition, HDACs deacetylate numerous nonhistone cellular substrates that govern a wide array of biological processes including cancer initiation and progression. This review will discuss the role of HDACs in cancer and the therapeutic potential of HDAC inhibitors (HDACi) as emerging drugs in cancer treatment.

Lysyl Oxidase (LOX) Transcriptionally Regulates SNAI2 Expression and TIMP4 Secretion in Human Cancers

PURPOSE

Epithelial-to-mesenchymal transition (EMT) is important in cancer progression and metastasis. We and others have previously reported that lysyl oxidase (LOX) is overexpressed in aggressive cancers, is associated with increased mortality, and regulates EMT. However, the mechanism by which LOX mediates EMT is unknown. In this study, we investigated the effect of LOX on mediators of EMT.

EXPERIMENTAL DESIGN

We used chromatin immunoprecipitation and promoter luciferase assays to determine the target gene of LOX. To determine the effects of SNAI2 in vivo, we used our metastatic anaplastic thyroid cancer (ATC) mouse model. To investigate the effects of LOX and SNAI2 on MMPs and TIMPs, protein arrays were used. Primary tumors from patients with metastatic, breast and colon cancer, and tissue array for thyroid cancer were assessed for SNAI2 and TIMP4 expression by immunohistochemistry.

RESULTS

We found that LOX knockdown decreases SNAI2 expression in cancer cell lines. Furthermore, knockdown of LOX reduced SNAI2 expression in a metastatic mouse model of thyroid cancer. We also demonstrated that LOX binds and transactivates the SNAI2 promoter. We found a direct correlation in thyroid and breast cancer samples between LOX and SNAI2 expression. To understand how LOX/SNAI2 axis mediates these effects, we performed a comprehensive analysis of MMPs/TIMPs. LOX and SNAI2 depletion reduced TIMP4 secretion. Analysis of SNAI2 and TIMP4 expression showed overexpression of both proteins in aggressive thyroid, colon, and breast tumors.

CONCLUSIONS

Our findings provide new evidence that LOX regulates SNAI2 expression and that SNAI2-mediated TIMP4 secretion plays a role in cancer progression. Clin Cancer Res; 22(17); 4491-504. ©2016 AACR.

An epithelial marker promoter induction screen identifies histone deacetylase inhibitors to restore epithelial differentiation and abolishes anchorage independence growth in cancers

Epithelial–mesenchymal transition (EMT), a crucial mechanism in development, mediates aggressiveness during carcinoma progression and therapeutic refractoriness. The reversibility of EMT makes it an attractive strategy in designing novel therapeutic approaches. Therefore, drug discovery pipelines for EMT reversal are in need to discover emerging classes of compounds. Here, we outline a pre-clinical drug screening platform for EMT reversal that consists of three phases of drug discovery and validation. From the Phase 1 epithelial marker promoter induction (EpI) screen on a library consisting of compounds being approved by Food and Drug Administration (FDA), Vorinostat (SAHA), a histone deacetylase inhibitor (HDACi), is identified to exert EMT reversal effects by restoring the expression of an epithelial marker, E-cadherin. An expanded screen on 41 HDACi further identifies 28 compounds, such as class I-specific HDACi Mocetinosat, Entinostat and CI994, to restore E-cadherin and ErbB3 expressions in ovarian, pancreatic and bladder carcinoma cells. Mocetinostat is the most potent HDACi to restore epithelial differentiation with the lowest concentration required for 50% induction of epithelial promoter activity (EpIC-50).The HDACi exerts paradoxical effects on EMT transcriptional factors such as SNAI and ZEB family and the effects are context-dependent in epithelial- and mesenchymal-like cells. In vitro functional studies further show that HDACi induced significant increase in anoikis and decrease in spheroid formation in ovarian and bladder carcinoma cells with mesenchymal features. This study demonstrates a robust drug screening pipeline for the discovery of compounds capable of restoring epithelial differentiation that lead to significant functional lethality.

MicroRNAs let7 expression in thyroid cancer: correlation with their deputed targets HMGA2 and SLC5A5

PURPOSE

Thyroid cancer (TC), the most common endocrine malignancy, increases its incidence worldwide. MicroRNAs have been shown to be abnormally expressed in tumors and could represent valid diagnostic markers for patients affected by TC. Our aim was to analyze the expression of tumorsuppressor hsa-let7b-5p and hsa-let7f-5p, together with their predicted targets SLC5A5 (NIS) and HMGA2, in papillary (PTC), follicular (FTC) and anaplastic (ATC).

METHODS

8 FTC, 14 PTC, 12 ATC and three normal thyroid tissue samples were analyzed for the expression of pre-let7b, hsa-let7b-5p and hsa-let7f-5p as SLC5A5 and HMGA2 by RT-qPCR. Data were analyzed by REST 2008.

RESULTS

FTC patients showed a significant down-regulation of hsa-let7b-5p and its precursor. hsa-let7f-5p was overexpressed, and SLC5A5 was strongly suppressed. HMGA2 was overexpressed, reflecting no correlation with its regulatory let7 miRNAs. PTC samples were characterized by up-regulation of hsa-let7b-5p, its precursor and hsa-let7f-5p. SLC5A5 was strongly suppressed in comparison with normal thyroid tissue. HMGA2 was overexpressed, as shown in FTC, also. ATC samples showed a similar miRNAs profile as PTC. In contrast with FTC and PTC, these patients showed a stable or up-regulated SLC5A5 and HMGA2.

CONCLUSIONS

Expression of HMGA2 is not correlated with the regulatory let7 miRNAs. Interestingly, SLC5A5 was down-regulated in FTC and PTC. Its expression could be modulated by hsa-let-7f-5p. ATC showed a loss of SLC5A5/hsa-let7f-5p correlation. SLC5A5, in ATC, needs further investigation to clarify the genetic/epigenetic mechanism altering its expression.

Functional Genomic Landscape of Human Breast Cancer Drivers, Vulnerabilities, and Resistance

Large-scale genomic studies have identified multiple somatic aberrations in breast cancer, including copy number alterations and point mutations. Still, identifying causal variants and emergent vulnerabilities that arise as a consequence of genetic alterations remain major challenges. We performed whole-genome small hairpin RNA (shRNA) "dropout screens" on 77 breast cancer cell lines. Using a hierarchical linear regression algorithm to score our screen results and integrate them with accompanying detailed genetic and proteomic information, we identify vulnerabilities in breast cancer, including candidate "drivers," and reveal general functional genomic properties of cancer cells. Comparisons of gene essentiality with drug sensitivity data suggest potential resistance mechanisms, effects of existing anti-cancer drugs, and opportunities for combination therapy. Finally, we demonstrate the utility of this large dataset by identifying BRD4 as a potential target in luminal breast cancer and PIK3CA mutations as a resistance determinant for BET-inhibitors.

CUDC-101, a Novel Inhibitor of Full-Length Androgen Receptor (flAR) and Androgen Receptor Variant 7 (AR-V7) Activity: Mechanism of Action and In Vivo Efficacy

Castration-resistant prostate cancer (CRPC) is an androgen receptor (AR)-dependent disease expected to cause the death of more than 27,000 Americans in 2015. There are only a few available treatments for CRPC, making the discovery of new drugs an urgent need. We report that CUDC-101 (an inhibitor od HER2/NEU, EGFR and HDAC) inhibits both the full length AR (flAR) and the AR variant AR-V7. This observation prompted experiments to discover which of the known activities of CUDC-101 is responsible for the inhibition of flAR/AR-V7 signaling. We used pharmacologic and genetic approaches, and found that the effect of CUDC-101 on flAR and AR-V7 was duplicated only by other HDAC inhibitors, or by silencing the HDAC isoforms HDAC5 and HDAC10. We observed that CUDC-101 treatment or AR-V7 silencing by RNAi equally reduced transcription of the AR-V7 target gene, PSA, without affecting viability of 22Rv1 cells. However, when cellular proliferation was used as an end point, CUDC-101 was more effective than AR-V7 silencing, raising the prospect that CUDC-101 has additional targets beside AR-V7. In support of this, we found that CUDC-101 increased the expression of the cyclin-dependent kinase inhibitor p21, and decreased that of the oncogene HER2/NEU. To determine if CUDC-101 reduces growth in a xenograft model of prostate cancer, this drug was given for 14 days to castrated male SCID mice inoculated with 22Rv1 cells. Compared to vehicle, CUDC-101 reduced xenograft growth in a statistically significant way, and without macroscopic side effects. These studies demonstrate that CUDC-101 inhibits wtAR and AR-V7 activity and growth of 22Rv1 cells in vitro and in vivo. These effects result from the ability of CUDC-101 to target not only HDAC signaling, which was associated with decreased flAR and AR-V7 activity, but multiple additional oncogenic pathways. These observations raise the possibility that treatment of CRPC may be achieved by using similarly multi-targeted approaches.

Epigenetic-based therapy: From single- to multi-target approaches

The treatment of cancer has traditionally been based on the identification of a single molecule and/or enzymatic function (target) responsible for a particular phenotype, and therefore on the ability to stimulate, attenuate or inhibit its activity through the use of selective compounds. However, cancer is no longer considered a disease caused by a single factor, but is now recognized as a multi-factorial disorder. Genetic, epigenetic and metabolic factors all contribute to neoplasia, causing significant changes in molecular networks that govern cell growth, development, death and specialization. Consequently, many antitumor therapies are no longer directed against a single target but the biological system as a whole, in which functions determining the onset and maintenance of a physio-pathological state are modulated. The field of epi-drug discovery is currently in a transitional phase where the search for putative anticancer drugs is shifting from single-target-oriented molecules to network-active compounds and to epi-drugs used in combination with other epi-agents and with traditional chemotherapeutics. This review illustrates the pros and cons of each therapeutic option, providing examples in support of single-target and multi (network)-target epi-drug approaches.