Effect of dasatinib against thyroid cancer cell lines in vitro and a xenograft model in vivo

Exploring the clinical utility of angioinvasion markers in papillary thyroid cancer: a literature review

Papillary thyroid cancer (PTC) is the most common type of thyroid cancer, and angioinvasion, the invasion of blood vessels by cancer cells, is a crucial pathological feature associated with disease progression and poor prognosis. Thus, a comprehensive search of scientific databases was conducted to identify relevant studies investigating angioinvasion markers in PTC. The selected studies were reviewed and analyzed to assess the clinical significance and potential utility of these markers in predicting angioinvasion and guiding treatment decisions. Numerous studies have investigated various markers associated with angioinvasion in PTC, including oxidative stress, vascular endothelial growth factor (VEGF), matrix metalloproteinases (MMPs), and other angiogenic factors. The results indicate that increased expression of these markers is correlated with the presence and extent of angioinvasion in PTC. Moreover, some studies suggest that these markers can serve as prognostic indicators and guide therapeutic strategies, such as selecting patients for more aggressive treatment approaches or targeted therapies. The findings from the reviewed literature highlight the potential clinical utility of angioinvasion markers in PTC. The identification and validation of reliable markers can aid in assessing the risk of angioinvasion, predicting disease progression, and optimizing treatment decisions for patients with PTC. However, further research and validation on larger patient cohorts are necessary to establish the robustness and generalizability of these markers in clinical practice.

Analysis of NIS Plasma Membrane Interactors Discloses Key Regulation by a SRC/RAC1/PAK1/PIP5K/EZRIN Pathway with Potential Implications for Radioiodine Re-Sensitization Therapy in Thyroid Cancer

The functional expression of the sodium-iodide symporter (NIS) at the membrane of differentiated thyroid cancer (DTC) cells is the cornerstone for the use of radioiodine (RAI) therapy in these malignancies. However, NIS gene expression is frequently downregulated in malignant thyroid tissue, and 30% to 50% of metastatic DTCs become refractory to RAI treatment, which dramatically decreases patient survival. Several strategies have been attempted to increase the NIS mRNA levels in refractory DTC cells, so as to re-sensitize refractory tumors to RAI. However, there are many RAI-refractory DTCs in which the NIS mRNA and protein levels are relatively abundant but only reduced levels of iodide uptake are detected, suggesting a posttranslational failure in the delivery of NIS to the plasma membrane (PM), or an impaired residency at the PM. Because little is known about the molecules and pathways regulating NIS delivery to, and residency at, the PM of thyroid cells, we here employed an intact-cell labeling/immunoprecipitation methodology to selectively purify NIS-containing macromolecular complexes from the PM. Using mass spectrometry, we characterized and compared the composition of NIS PM complexes to that of NIS complexes isolated from whole cell (WC) lysates. Applying gene ontology analysis to the obtained MS data, we found that while both the PM-NIS and WC-NIS datasets had in common a considerable number of proteins involved in vesicle transport and protein trafficking, the NIS PM complexes were particularly enriched in proteins associated with the regulation of the actin cytoskeleton. Through a systematic validation of the detected interactions by co-immunoprecipitation and Western blot, followed by the biochemical and functional characterization of the contribution of each interactor to NIS PM residency and iodide uptake, we were able to identify a pathway by which the PM localization and function of NIS depends on its binding to SRC kinase, which leads to the recruitment and activation of the small GTPase RAC1. RAC1 signals through PAK1 and PIP5K to promote ARP2/3-mediated actin polymerization, and the recruitment and binding of the actin anchoring protein EZRIN to NIS, promoting its residency and function at the PM of normal and TC cells. Besides providing novel insights into the regulation of NIS localization and function at the PM of TC cells, our results open new venues for therapeutic intervention in TC, namely the possibility of modulating abnormal SRC signaling in refractory TC from a proliferative/invasive effect to the re-sensitization of these tumors to RAI therapy by inducing NIS retention at the PM.

Resistance to Src inhibition alters the BRAF-mutant tumor secretome to promote an invasive phenotype and therapeutic escape through a FAK>p130Cas>c-Jun signaling axis

Few therapy options exist for patients with advanced papillary and anaplastic thyroid cancer. We and others have previously identified c-Src as a key mediator of thyroid cancer pro-tumorigenic processes and a promising therapeutic target for thyroid cancer. To increase the efficacy of targeting Src in the clinic, we sought to define mechanisms of resistance to the Src inhibitor, dasatinib, to identify key pathways to target in combination. Using a panel of thyroid cancer cell lines expressing clinically relevant mutations in BRAF or RAS, which were previously developed to be resistant to dasatinib, we identified a switch to a more invasive phenotype in the BRAF-mutant cells as a potential therapy escape mechanism. This phenotype switch is driven by FAK kinase activity, and signaling through the p130Cas>c-Jun signaling axis. We have further shown this more invasive phenotype is accompanied by alterations in the secretome through the increased expression of pro-inflammatory cytokines, including IL-1β, and the pro-invasive metalloprotease, MMP-9. Furthermore, IL-1β signals via a feedforward autocrine loop to promote invasion through a FAK>p130Cas>c-Jun>MMP-9 signaling axis. We further demonstrate that upfront combined inhibition of FAK and Src synergistically inhibits growth and invasion, and induces apoptosis in a panel of BRAF- and RAS-mutant thyroid cancer cell lines. Together our data demonstrate that acquired resistance to single-agent Src inhibition promotes a more invasive phenotype through an IL-1β>FAK>p130Cas>c-Jun >MMP signaling axis, and that combined inhibition of FAK and Src has the potential to block this inhibitor-induced phenotype switch.

A novel ex vivo tumor system identifies Src-mediated invasion and metastasis in mesenchymal tumor cells in non-small cell lung cancer

Lung cancer is the foremost cause of cancer related deaths in the U.S. It is a heterogeneous disease composed of genetically and phenotypically distinct tumor cells surrounded by heterotypic cells and extracellular matrix dynamically interacting with the tumor cells. Research in lung cancer is often restricted to patient-derived tumor specimens, in vitro cell cultures and limited animal models, which fail to capture the cellular or microenvironment heterogeneity of the tumor. Therefore, our knowledge is primarily focused on cancer-cell autonomous aberrations. For a fundamental understanding of lung cancer progression and an exploration of therapeutic options, we focused our efforts to develop an Ex Vivo Tumor platform to culture tumors in 3D matrices, which retains tumor cell heterogeneity arising due to in vivo selection pressure and environmental influences and recapitulate responses of tumor cells to external manipulations. To establish this model, implanted syngeneic murine tumors from a mutant KRAS/p53 model were harvested to yield multicellular tumor aggregates followed by culture in 3D extracellular matrices. Using this system, we identified Src signaling as an important driver of invasion and metastasis in lung cancer and demonstrate that EVTs are a robust experimental tool bridging the gap between conventional in vitro and in vivo models.

Src-mediated regulation of the PI3K pathway in advanced papillary and anaplastic thyroid cancer

Advanced stages of papillary and anaplastic thyroid cancer continue to be plagued by a dismal prognosis, which is a result of limited effective therapies for these cancers. Due to the high proportion of thyroid cancers harboring mutations in the MAPK pathway, the MAPK pathway has become a focal point for therapeutic intervention in thyroid cancer. Unfortunately, unlike melanoma, a similar responsiveness to MAPK pathway inhibition has yet to be observed in thyroid cancer patients. To address this issue, we have focused on targeting the non-receptor tyrosine kinase, Src, and we and others have demonstrated that targeting Src results in inhibition of growth, invasion, and migration both in vitro and in vivo, which can be enhanced through the combined inhibition of Src and the MAPK pathway. Therefore, we examined the efficacy of the combination therapy across a panel of thyroid cancer cell lines representing common oncogenic drivers (BRAF, RAS, and PIK3CA). Interestingly, combined inhibition of Src and the MAPK pathway overcomes intrinsic dasatinib resistance in cell lines where both the MAPK and PI3K pathways are inhibited, which we show is likely due to the regulation of the PI3K pathway by Src in these responsive cells. Interestingly, we have mapped downstream phosphorylation of rpS6 as a key biomarker of response, and cells that maintain rpS6 phosphorylation likely represent drug tolerant persisters. Altogether, the combined inhibition of Src and the MAPK pathway holds great promise for improving the overall survival of advanced thyroid cancer patients with BRAF and RAS mutations, and activation of the PI3K pathway and rpS6 phosphorylation represent important biomarkers of response for patients treated with this therapy.

The Mitogen-Activated Protein Kinase Pathway Facilitates Resistance to the Src Inhibitor Dasatinib in Thyroid Cancer

Advanced stages of papillary and anaplastic thyroid cancer represent a highly aggressive subset, in which there are currently few effective therapies. We and others have recently demonstrated that c-SRC is a key mediator of growth, invasion, and metastasis, and therefore represents a promising therapeutic target in thyroid cancer. However, clinically, Src inhibitor efficacy has been limited, and therefore further insights are needed to define resistance mechanisms and determine rational combination therapies. We have generated four thyroid cancer cell lines with a greater than 30-fold increase in acquired resistance to the Src inhibitor dasatinib. Upon acquisition of dasatinib resistance, the two RAS-mutant cell lines acquired the c-SRC gatekeeper mutation (T341M), whereas the two BRAF-mutant cell lines did not. Accordingly, Src signaling was refractory to dasatinib treatment in the RAS-mutant dasatinib-resistant cell lines. Interestingly, activation of the MAPK pathway was increased in all four of the dasatinib-resistant cell lines, likely due to B-Raf and c-Raf dimerization. Furthermore, MAP2K1/MAP2K2 (MEK1/2) inhibition restored sensitivity in all four of the dasatinib-resistant cell lines, and overcame acquired resistance to dasatinib in the RAS-mutant Cal62 cell line, in vivo Together, these studies demonstrate that acquisition of the c-SRC gatekeeper mutation and MAPK pathway signaling play important roles in promoting resistance to the Src inhibitor dasatinib. We further demonstrate that up-front combined inhibition with dasatinib and MEK1/2 or ERK1/2 inhibitors drives synergistic inhibition of growth and induction of apoptosis, indicating that combined inhibition may overcome mechanisms of survival in response to single-agent inhibition. Mol Cancer Ther; 15(8); 1952-63. ©2016 AACR.

Dasatinib Attenuates Pressure Overload Induced Cardiac Fibrosis in a Murine Transverse Aortic Constriction Model

Reactive cardiac fibrosis resulting from chronic pressure overload (PO) compromises ventricular function and contributes to congestive heart failure. We explored whether nonreceptor tyrosine kinases (NTKs) play a key role in fibrosis by activating cardiac fibroblasts (CFb), and could potentially serve as a target to reduce PO-induced cardiac fibrosis. Our studies were carried out in PO mouse myocardium induced by transverse aortic constriction (TAC). Administration of a tyrosine kinase inhibitor, dasatinib, via an intraperitoneally implanted mini-osmotic pump at 0.44 mg/kg/day reduced PO-induced accumulation of extracellular matrix (ECM) proteins and improved left ventricular geometry and function. Furthermore, dasatinib treatment inhibited NTK activation (primarily Pyk2 and Fak) and reduced the level of FSP1 positive cells in the PO myocardium. In vitro studies using cultured mouse CFb showed that dasatinib treatment at 50 nM reduced: (i) extracellular accumulation of both collagen and fibronectin, (ii) both basal and PDGF-stimulated activation of Pyk2, (iii) nuclear accumulation of Ki67, SKP2 and histone-H2B and (iv) PDGF-stimulated CFb proliferation and migration. However, dasatinib did not affect cardiomyocyte morphologies in either the ventricular tissue after in vivo administration or in isolated cells after in vitro treatment. Mass spectrometric quantification of dasatinib in cultured cells indicated that the uptake of dasatinib by CFb was greater that that taken up by cardiomyocytes. Dasatinib treatment primarily suppressed PDGF but not insulin-stimulated signaling (Erk versus Akt activation) in both CFb and cardiomyocytes. These data indicate that dasatinib treatment at lower doses than that used in chemotherapy has the capacity to reduce hypertrophy-associated fibrosis and improve ventricular function.

Dasatinib suppresses invasion and induces apoptosis in nasopharyngeal carcinoma

Dasatinib, an orally available tyrosine kinas inhibitor (TKI), potently inhibits SRC which was found to activate RTKs that induce trastuzumab de novo and acquired resistance. To evaluate the potential of Dasatinib in the treatment of Nasopharyngeal Carcinoma, we used a variety of assays to measure its effects on cell proliferation, apoptosis, and migration. This work aimed to test the antitumor effects of the inhibitor in vitro to determine whether in vivo analyses were warranted. Cell growth rate and 50% inhibitory concentration was calculated by MTT assay. Dasatinib-induced apoptotic cells were investigated by Annexin V/PI staining. Proteins from cell extracts were analyzed by Western blot. Cell motility was investigated by Transwell. Our study showed that Dasatinib significantly inhibited CNE2 proliferation and induced apoptosis in vitro. Phospho-AKT, phospho-MEK, phospho-ERK expression was significantly reduced when treated with dasatinib which means the downregulated RAS/RAF/MEK/ERK and PI3K/AKT pathway activity. Dasatinib significantly inhibited the motility of CNE2 as well as Phospho-FAK expression. Dasatinib exhibit antitumor effects of nasopharyngeal carcinoma by downregulating MAPK and PI3K/AKT pathways activity and FAK phosphorylation. This suggests that dasatinib would have therapeutic activity against NPC.

Combined BRAF(V600E)- and SRC-inhibition induces apoptosis, evokes an immune response and reduces tumor growth in an immunocompetent orthotopic mouse model of anaplastic thyroid cancer

Anaplastic (ATC) and refractory papillary thyroid cancer (PTC) lack effective treatments. Inhibition of either oncogenic BRAF or SRC has marked anti-tumor effects in mouse models of thyroid cancer, however, neither drug induces notable apoptosis. Here we report that the SRC-inhibitor dasatinib further sensitizes BRAFV600E-positive thyroid cancer cells to the BRAFV600E-inhibitor PLX4720. Combined treatment with PLX4720 and dasatinib synergistically inhibited proliferation and reduced migration in PTC and ATC cells. Whereas PLX4720 did not induce robust apoptosis in thyroid cancer cells, combined treatment with dasatinib induced apoptosis in 4 of 6 lines. In an immunocompetent orthotopic mouse model of ATC, combined PLX4720 and dasatinib treatment significantly reduced tumor volume relative to PLX4720 treatment alone. Immune cell infiltration was increased by PLX4720 treatment and this effect was maintained in mice treated with both PLX4720 and dasatinib. Further, combined treatment significantly increased caspase 3 cleavage in vivo relative to control or either treatment alone. In conclusion, combined PLX4720 and dasatinib treatment induces apoptosis, increases immune cell infiltration and reduces tumor volume in a preclinical model of ATC, suggesting that the combination of these FDA-approved drugs may have potential for the treatment of patients with ATC or refractory PTC.

Genetics and epigenetics of sporadic thyroid cancer

Thyroid carcinoma is the most common endocrine malignancy, and although the disease generally has an excellent prognosis, therapeutic options are limited for patients not cured by surgery and radioiodine. Thyroid carcinomas commonly contain one of a small number of recurrent genetic mutations. The identification and study of these mutations has led to a deeper understanding of the pathophysiology of this disease and is providing new approaches to diagnosis and therapy. Papillary thyroid carcinomas usually contain an activating mutation in the RAS cascade, most commonly in BRAF and less commonly in RAS itself or through gene fusions that activate RET. A chromosomal translocation that results in production of a PAX8-PPARG fusion protein is found in follicular carcinomas. Anaplastic carcinomas may contain some of the above changes as well as additional mutations. Therapies that are targeted to these mutations are being used in patient care and clinical trials.

Belinostat and panobinostat (HDACI): in vitro and in vivo studies in thyroid cancer

Purpose

Advanced thyroid cancer responds poorly to most therapies. New therapies and combinations are needed. The aim of this study was to examine both in vitro and in vivo activity of two relatively new histone deacetylase inhibitors (HDACIs), belinostat and panobinostat, and a variety of tyrosine kinase inhibitors (TKIs) against a panel of nine human thyroid cancer cell lines.

Methods

The anti-proliferative activity and the effects of HDACIs, TKIs and their combinations on thyroid cancer cells were determined by cytotoxicity assays, microarray and immunoblot analyses. Synergism between HDACIs and TKIs was assessed by the median effects model of Chou-Talalay (Calcusyn^®).

Results

Belinostat and panobinostat were active against the thyroid cancer cell lines irrespective of their mutational composition, and belinostat was effective in preventing growth of human thyroid cancer xenografts in immunodeficient mice. Further studies showed that both HDACIs induced apoptosis. HDACI also elevated acetylated histone 3, p21^Waf, and PARP, and decreased levels of phosphorylated ERK and AKT (Ser473). RNA assay analysis suggested both HDACIs modulated genes associated with the cell cycle, DNA damage and apoptosis. Most of the TKI (pazopanib, motesanib, sorafenib and dasatinib) were either inactive in vitro or were active only at high doses. However, the novel combinations of either pazopanib or dasatinib TKIs with either belinostat or panobinostat synergistically inhibited cell growth of thyroid cancer cells in vitro.

Conclusions

In summary, these HDACIs either alone or combined with selected TKIs may have a role in treatment of aggressive thyroid cancer.

Electronic supplementary material

The online version of this article (doi:10.1007/s00432-013-1465-6) contains supplementary material, which is available to authorized users.

Targeted inhibition of Src kinase with dasatinib blocks thyroid cancer growth and metastasis

PURPOSE

There are no effective therapies for patients with poorly differentiated papillary thyroid cancer (PTC) or anaplastic thyroid cancer (ATC), and metastasis to the bone represents a significantly worse prognosis. Src family kinases (SFKs) are overexpressed and activated in numerous tumor types and have emerged as a promising therapeutic target, especially in relation to metastasis. We recently showed that Src is overexpressed and activated in thyroid cancer. We therefore tested whether inhibition of Src with dasatinib (BMS-354825) blocks thyroid cancer growth and metastasis.

EXPERIMENTAL DESIGN

The effects of dasatinib on thyroid cancer growth, signaling, cell cycle, and apoptosis were evaluated in vitro. The therapeutic efficacy of dasatinib was further tested in vivo using an orthotopic and a novel experimental metastasis model. Expression and activation of SFKs in thyroid cancer cells was characterized, and selectivity of dasatinib was determined using an Src gatekeeper mutant.

RESULTS

Dasatinib treatment inhibited Src signaling, decreased growth, and induced cell-cycle arrest and apoptosis in a subset of thyroid cancer cells. Immunoblotting showed that c-Src and Lyn are expressed in thyroid cancer cells and that c-Src is the predominant SFK activated. Treatment with dasatinib blocked PTC tumor growth in an orthotopic model by more than 90% (P = 0.0014). Adjuvant and posttreatment approaches with dasatinib significantly inhibited metastasis (P = 0.016 and P = 0.004, respectively).

CONCLUSION

These data provide the first evidence that Src is a central mediator of thyroid cancer growth and metastasis, indicating that Src inhibitors may have a higher therapeutic efficacy in thyroid cancer, as both antitumor and antimetastatic agents.