Combined BRAFV600E- 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 BRAF^V600E-positive thyroid cancer cells to the BRAF^V600E-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.     

Novel mechanisms of resistance to vemurafenib in melanoma – V600E B-Raf reversion and switching VEGF-A splice isoform expression

Targeting activating mutations in the proto-oncogene B-Raf, in melanoma, has led to increases in progression free survival. Treatment with vemurafenib, which inhibits the most common activating-mutated form of B-Raf (B-Raf^V600E), eventually results in resistance to therapy. VEGF-A is the principal driver of angiogenesis in primary and metastatic lesions. The bioactivity of VEGF-A is dependent upon alternative RNA splicing and pro-angiogenic isoforms of VEGF-A are upregulated in many disease states dependent upon angiogenesis, including cancers. Using techniques including RT-PCR, Western blotting, ELISA and luciferase reporter assays, the effect of vemurafenib on proliferation, ERK1/2 phosphorylation and the levels of pro- and anti-angiogenic VEGF-A isoforms was investigated in melanoma cell types expressing either wild-type B-Raf or B-Raf^V600E, including a primary melanoma culture derived from a highly vascularised and active nodule taken from a patient with a V600E mutant melanoma. The primary melanoma culture was characterised and found to have reverted to wild-type B-Raf. In B-Raf^V600E A375 cells ERK1/2 phosphorylation, pro-angiogenic VEGF-A mRNA, total VEGF-A protein expression and VEGF-A 3’UTR activity were all decreased in a concentration-dependent manner by vemurafenib. Conversely vemurafenib treatment of wild-type B-Raf cells significantly increased ERK1/2 phosphorylation, pro-angiogenic VEGF-A mRNA and total VEGF-A expression in a concentration-dependent manner. A switch to pro-angiogenic VEGF-A isoforms, with a concomitant upregulation of expression by increasing VEGF-A mRNA stability, may be an additional oncogenic and pathological mechanism in B-Raf^V600E melanomas, which promotes tumor-associated angiogenesis and melanoma-genesis. We have also identified the genetic reversal of B-Raf^V600E to wild-type in an active melanoma nodule taken from a V600E-positive patient and continued vemurafenib treatment for this patient is likely to have had a detrimental effect by promoting B-Raf^WT activity.     

Oncogenic B-Raf abrogates the AKT/B-Raf/Mps1 interaction in melanoma cells

Activating B-Raf mutations that deregulate the mitogen-activated protein kinase (MAPK) pathway commonly occur in cancer. Although B-Raf^V600E induces increased Mps1 protein contributing to centrosome amplification and chromosome instability, the regulatory mechanisms of Mps1 in melanoma cells is not fully understood. Here, we report that Mps1/AKT and B-Raf^WT/ERK signaling form an auto-regulatory negative feedback loop in melanoma cells; notably, oncogenic B-Raf^V600E abrogates the negative feedback loop, contributing the aberrant Mps1 functions and tumorigenesis. Our findings raise the possibility that targeting the oncogenic B-Raf and Mps1, especially when used in combination could potentially provide great therapeutic opportunities for cancer treatment.     

Suppression of B-RafV600E melanoma cell survival by targeting mitochondria using triphenyl-phosphonium-conjugated nitroxide or ubiquinone

Most BRAF-mutated melanomas initially responsive to the FDA-approved inhibitors preferentially targeting B-Raf mutated in Val600 residue eventually relapse, requiring additional therapeutic modalities. Recent studies report the significance of metabolic reprograming in mitochondria for maintenance of BRAF-mutated melanomas and for development of their drug resistance to B-Raf inhibitors, providing a rationale for targeting mitochondria as a potential therapeutic strategy for melanoma. We therefore determined whether mitochondria-targeted metabolism-interfering agents can effectively suppress human B-Raf^V600E melanoma cell lines and their dabrafenib/PLX4032-resistant progenies using mitochondria-targeted carboxy-proxyl (Mito-CP) and ubiquinone (Mito-Q). These agents exhibited comparable efficacy to PLX4032 in suppressing SK-MEL28, A375, and RPMI-7951 cells in vitro. As determined in SK-MEL28 and A375 cells, Mito-CP induced apoptotic cell death mediated by mitochondrial membrane depolarization and subsequent oxidative stress, which PLX4032 could not induce. Of note, Mito-CP also effectively suppressed PLX4032-resistant progenies of SK-MEL28 and A375. Moreover, when orally administered, Mito-CP suppressed SK-MEL28 xenografts in mice as effectively as PLX4032 without serious adverse effects. These data demonstrate that mitochondria-targeted agents have therapeutic potential to effectively suppress BRAF–mutated melanomas via an effect(s) distinct from those of B-Raf inhibitors.     

小白菊内酯对甲状腺癌TPC-1细胞增殖、迁移和侵袭的影响及机制

目的:研究小白菊内酯(parthenolide,PTL)对甲状腺癌TPC-1细胞增殖、迁移和侵袭的影响及其可能的机制.方法:应用0、2.5、5、10、20μmol/L的PTL处理甲状腺癌TPC-1细胞24 h,CCK-8法检测不同浓度的PTL对TPC-1细胞增殖的影响;划痕实验和Transwell实验观察PTL对TPC...     

The association of the BRAF(V600E) mutation with prognostic factors and poor clinical outcome in papillary thyroid cancer: a meta-analysis

BACKGROUND:

The effects of the BRAF^V600E mutation on prognostic factors and poor clinical outcomes in papillary thyroid cancer (PTC) have not been fully quantified. The authors performed comprehensive meta‐analysis to assess the strength of associations between these conditions and the BRAF^V600E mutation.

METHODS:

The authors identified the clinical studies that examined the association of the BRAF^V600E mutation in surgical specimens with clinicopathologic outcomes between January 2003 and October 2010 using the Medline database. One hundred thirty‐one relevant studies were hand‐searched. The authors selected 27 studies that included 5655 PTC patients. They calculated the pooled odds ratios (ORs) or risk ratios with 95% confidence intervals (CIs) for each study using a random effect model.

RESULTS:

The average prevalence rate of the BRAF^V600E mutation was 49.4%. In 26 studies, compared with the patients who had the wild‐type BRAF genes, the PTC patients with the BRAF^V600E mutation had increased ORs of an extrathyroidal invasion (OR, 2.14; 95% CI, 1.68‐2.73), a lymph node metastasis (OR, 1.54; 95% CI, 1.21‐1.97), and an advanced TNM stage (OR, 2.00; 95% CI, 1.61‐2.49). In 8 studies, patients with the mutation had 2.14‐fold increased risk of recurrent and persistent disease (95% CI, 1.67‐2.74). The associations were generally consistent across the different study populations.

CONCLUSIONS:

This meta‐analysis demonstrates that the BRAF^V600E mutation is closely related to the high‐risk clinicopathological factors and poorer outcome of PTC. The results obtained here suggest that the BRAF^V600E mutation should be considered as a poor prognostic marker in PTC and may lead to better management for individual patients. Cancer 2012;. © 2011 American Cancer Society.     

BRAFV600E melanoma cells secrete factors that activate stromal fibroblasts and enhance tumourigenicity

Background:

Melanoma, the most lethal form of skin cancer, is responsible for over 80% of all skin cancer deaths and is highly metastatic, readily spreading to the lymph nodes or metastasising to other organs. The frequent genetic mutation found in metastatic melanoma, BRAF^V600E, results in constitutive activation of the mitogen-activated protein kinase pathway.

Methods:

In this study, we utilised genetically engineered melanoma cell lines and xenograft mouse models to investigate how BRAF^V600E affected cytokine (IL-1β, IL-6, and IL-8) and matrix metalloproteinase-1 (MMP-1) expression in tumour cells and in human dermal fibroblasts.

Results:

We found that BRAF^V600E melanoma cells expressed higher levels of these cytokines and of MMP-1 than wild-type counterparts. Further, conditioned medium from the BRAF^V600E melanoma cells promoted the activation of stromal fibroblasts, inducing expression of SDF-1 and its receptor CXCR4. This increase was mitigated when the conditioned medium was taken from melanoma cells treated with the BRAF^V600E specific inhibitor, vemurafenib.

Conclusions:

Our findings highlight the role of BRAF^V600E in activating the stroma and suggest a mechanistic link between BRAF^V600E and MMP-1 in mediating melanoma progression and in activating adjacent fibroblasts in the tumour microenvironment.     

EGFR blockade prevents glioma escape from BRAFV600E targeted therapy

Mutational activation of BRAF (BRAF^V600E) occurs in pediatric glioma and drives aberrant MAPK signaling independently of upstream cues. Targeted monotherapy against BRAF^V600E displays efficacy in pre-clinical models of glioma, however xenograft tumors adapt rapidly and escape from the growth-inhibitory effects of BRAF-targeted therapy. Here, we show that intrinsic resistance to a BRAF^V600E specific inhibitor stems, in part, from feedback activation of EGFR and downstream signaling pathways. BRAF^V600E inhibition suppresses MAPK signaling, which in turn downregulates the EGFR phosphatase PTPN9, resulting in sustained EGFR phosphorylation and enhanced EGFR activity. We demonstrated that overexpression of PTPN9 reduces EGFR phosphorylation and cooperates with BRAF^V600E inhibitor PLX4720 to reduce MAPK and Akt signaling, resulting in decreased glioma cell viability. Moreover, pharmacologic inhibition of EGFR combined with inhibition of BRAF^V600E to reduce growth of glioma cell lines and orthotopic glioma xenograft by decreasing tumor cell proliferation while increasing apoptosis, with resultant significant extension of animal subject survival. Our data support clinical evaluation of BRAF^V600E and EGFR targeted therapy in treating BRAF^V600E glioma.     

ZNRF3在甲状腺肿瘤组织中的表达以及在甲状腺癌细胞中的功能研究

目的 检测ZNRF3基因在不同分化程度甲状腺癌组织标本和细胞中的表达情况并探讨其在甲状腺癌中的作用.方法 应用免疫组织化学技术检测35例乳头状甲状腺癌和10例低分化甲状腺癌组织中ZNRF3蛋白的表达.RT-PCR检测ZNRF3基因在乳头状甲状腺癌TPC-1和低分化甲状腺癌8505C细胞株中的表达.通过慢病毒沉默TPC-1细胞中的ZNRF3基因,CCK-8与Transwell分别检测ZNRF3基因沉默后TPC-1细胞株增殖和侵袭迁移情况.结果 免疫组织化学和RT-PCR分别检测发现,ZNRF3基因在乳头状甲状腺癌组织及细胞株中的表达明显高于低分化甲状腺癌组织及细胞,差异有统计学意义(4.83±0.44∶3.13±0.59,t=2.20,P＜0.05;1.01 ±0.06∶0.21 ±0.04,t=11.80,P＜0.01).将TPC-1细胞株中ZNRF3基因沉默后,通过CCK-8检测细胞增殖发现,细胞培养72 h后细胞增殖能力显著增强,差异有统计学意义(0.96±0.10∶0.64±0.05,t=3.19,P＜0.05);并且Transwell检测细胞侵袭与转移发现,细胞侵袭(0.12±0.01∶0.09±0.00,t=5.48,P＜0.01)与迁移能力(0.22±0.01∶0.17±0.01,t=4.58,P＜0.05)有所增强,差异有统计学意义.结论 ZNRF3在乳头状甲状腺癌中的表达高于低分化甲状腺癌,ZNRF3在甲状腺肿瘤的发生发展中为抑癌基因.     

Stimulation of neoplastic mouse lung cell proliferation by alveolar macrophage-derived, insulin-like growth factor-1 can be blocked by inhibiting MEK and PI3K activation

Background

Colorectal cancer is a common disease that involves genetic alterations, such as inactivation of tumour suppressor genes and activation of oncogenes. Among them are RAS and BRAF mutations, which rarely coexist in the same tumour. Individual members of the Rho (Ras homology) GTPases contribute with distinct roles in tumour cell morphology, invasion and metastasis. The aim of this study is to dissect cell migration and invasion pathways that are utilised by BRAF^V600E as compared to KRAS^G12V and HRAS^G12V oncoproteins. In particular, the role of RhoA (Ras homolog gene family, member A), Rac1 (Ras-related C3 botulinum toxin substrate 1) and Cdc42 (cell division cycle 42) in cancer progression induced by each of the three oncogenes is described.

Methods

Colon adenocarcinoma cells with endogenous as well as ectopically expressed or silenced oncogenic mutations of BRAF^V600E, KRAS^G12V and HRAS^G12V were employed. Signalling pathways and Rho GTPases were inhibited with specific kinase inhibitors and siRNAs. Cell motility and invasion properties were correlated with cytoskeletal properties and Rho GTPase activities.

Results

Evidence presented here indicate that BRAF^V600E significantly induces cell migration and invasion properties in vitro in colon cancer cells, at least in part through activation of RhoA GTPase. The relationship established between BRAF^V600E and RhoA activation is mediated by the MEK-ERK pathway. In parallel, KRAS^G12V enhances the ability of colon adenocarcinoma cells Caco-2 to migrate and invade through filopodia formation and PI3K-dependent Cdc42 activation. Ultimately increased cell migration and invasion, mediated by Rac1, along with the mesenchymal morphology obtained through the Epithelial-Mesenchymal Transition (EMT) were the main characteristics rendered by HRAS^G12V in Caco-2 cells. Moreover, BRAF and KRAS oncogenes are shown to cooperate with the TGFβ-1 pathway to provide cells with additional transforming properties.

Conclusion

This study discriminates oncogene-specific cell migration and invasion pathways mediated by Rho GTPases in colon cancer cells and reveals potential new oncogene-specific characteristics for targeted therapeutics.     

lncRNA BLACAT1靶向结合miR-29a-3p调控甲状腺癌细胞TPC-1的生物学行为

目的:探讨长链非编码RNA BLACAT1(lncRNA BLACAT1)调控microRNA-29a-3p（miR-29a-3p）对甲状腺癌细胞恶性生物学行为的作用及其可能机制。方法:收集2018年06月至2019年03月在我院行甲状腺癌切除术的31例患者的肿瘤组织和相应的癌旁组织。采用qRT-PCR检测lncRNA BLACAT1、miR-29a-3p在甲状腺癌组织、癌旁组织、5种甲状腺癌细胞系（SW579、 PDTC-1、 HMGA1、 TPC-1、 KAT-5）及正常甲状腺细胞Nthy-ori 3-1中的表达水平;调控TPC-1甲状腺癌细胞系中lncRNA BLACAT1、miR-29a-3p的表达,采用CCK-8法检测细胞增殖情况,Transwell法检测细胞的迁移和侵袭能力。用生物信息分析和双荧光素酶报告基因法预测和验证lncRNA BLACAT1与miR-29a-3p的靶向关系。结果:与癌旁组织和正常甲状腺细胞相比,甲状腺癌组织和细胞系中lncRNA BLACAT1的表达水平显著上调,miR-29a-3p的表达水平显著下调（P＜0.05）;过表达lncRNA BLACAT1促进TPC-1细胞的增殖、迁移和侵袭;在甲状腺癌组织中lncRNA BLACAT1的表达水平与miR-29a-3p的表达水平呈负相关（r2 =0.492,P＜0.001）;双荧光素酶分析证实lncRNA BLACAT1能特异性结合miR-29a-3p,并能降低其表达;过表达miR-29a-3p抑制TPC-1细胞的增殖、迁移和侵袭,且miR-29a-3p可以抑制由lncRNA BLACAT1过表达引起的TPC-1细胞增殖、迁移和侵袭能力的增强。结论:lncRNA BLACAT1通过靶向调控miR-29a-3p表达影响甲状腺癌细胞的增殖、迁移和侵袭,从而促进甲状腺癌的发展。     

BRAFV600E protein expression and outcome from BRAF inhibitor treatment in BRAFV600E metastatic melanoma

Background:

To examine the association between level and patterns of baseline intra-tumoural BRAF^V600E protein expression and clinical outcome of BRAF^V600E melanoma patients treated with selective BRAF inhibitors.

Methods:

Fifty-eight BRAF^V600E metastatic melanoma patients treated with dabrafenib or vemurafenib on clinical trials had pre-treatment tumour BRAF^V600E protein expression immunohistochemically (IHC) assessed using the BRAF V600E mutant-specific antibody VE1. Sections were examined for staining intensity (score 1–3) and percentage of immunoreactive tumour cells, and from this an immunoreactive score (IRS) was derived (intensity × per cent positive/10). The presence of intra-tumoural heterogeneity for BRAF^V600E protein expression was also assessed. BRAF^V600E expression was correlated with RECIST response, time to best response (TTBR), progression-free survival (PFS) and overall survival (OS).

Results:

Expression was generally high (median IRS 28 (range 5–30)) and homogeneous (78%). Expression of mutated protein BRAF^V600E as measured by intensity, per cent immunoreactive cells, or IRS did not correlate with RECIST response, TTBR, PFS or OS, including on multivariate analysis. Heterogeneity of staining was seen in 22% of cases and did not correlate with outcome.

Conclusion:

In the current study population, IHC-measured pre-treatment BRAF^V600E protein expression does not predict response or outcome to BRAF inhibitor therapy in BRAF^V600E metastatic melanoma patients.     

Identification of MET and SRC Activation in Melanoma Cell Lines Showing Primary Resistance to PLX4032

PLX4032/vemurafenib is a first-in-class small-molecule BRAF^V600E inhibitor with clinical activity in patients with BRAF mutant melanoma. Nevertheless, drug resistance develops in treated patients, and strategies to overcome primary and acquired resistance are required. To explore the molecular mechanisms involved in primary resistance to PLX4032, we investigated its effects on cell proliferation and signaling in a panel of 27 genetically characterized patient-derived melanoma cell lines. Cell sensitivity to PLX4032 was dependent on BRAF^V600E and independent from other gene alterations that commonly occur in melanoma such as PTEN loss, BRAF, and MITF gene amplification. Two cell lines lacking sensitivity to PLX4032 and harboring a different set of genetic alterations were studied as models of primary resistance. Treatment with the MEK inhibitor UO126 but not with PLX4032 inhibited cell growth and ERK activation. Resistance to PLX4032 was maintained after CRAF down-regulation by siRNA indicating alternative activation of MEK-ERK signaling. Genetic characterization by multiplex ligation-dependent probe amplification and analysis of phosphotyrosine signaling by MALDI-TOF mass spectrometry analysis revealed the activation of MET and SRC signaling, associated with the amplification of MET and of CTNNB1 and CCND1 genes, respectively. The combination of PLX4032 with drugs or siRNA targeting MET was effective in inhibiting cell growth and reducing cell invasion and migration in melanoma cells with MET amplification; similar effects were observed after targeting SRC in the other cell line, indicating a role for MET and SRC signaling in primary resistance to PLX4032. Our results support the development of classification of melanoma in molecular subtypes for more effective therapies.     

LINC00243靶向miR-1976促进甲状腺癌细胞增殖、迁移和侵袭

目的:探讨长链非编码RNA（lncRNA）LINC00243对甲状腺癌细胞增殖、迁移及侵袭的影响和分子机制。方法:实时荧光定量PCR（qRT-PCR）检测正常甲状腺细胞系（HT-ori3）和甲状腺癌细胞系（BCPAP、TPC-1和SW1736）中LINC00243和miR-1976的表达水平。将LINC00243小干扰RNA（si-LINC00243）、miR-1976模拟物（miR-1976 mimics）分别转染TPC-1细胞。细胞计数试剂盒（CCK-8）检测细胞活力;Transwell实验检测细胞迁移和侵袭数量;蛋白质印记（Western blot）检测细胞周期素D1（CyclinD1）、基质金属蛋白酶2（MMP2）和MMP9的表达水平。双荧光素酶报告基因实验和qRT-PCR验证LINC00243和miR-1976的靶向调控关系。结果:与HT-ori3细胞比较,3种甲状腺癌细胞中LINC00243的表达水平显著升高,miR-1976的表达水平显著降低。沉默LINC00243或高表达miR-1976均可抑制TPC-1细胞的增殖、迁移和侵袭,抑制CyclinD1、MMP2和MMP9蛋白的表达（P＜0.05）。LINC00243靶向负性调控miR-1976表达。低表达miR-1976可逆转沉默LINC00243对TPC-1细胞增殖、迁移和侵袭的抑制作用（P＜0.05）。结论:在甲状腺癌细胞中,LINC00243呈高表达,miR-1976呈低表达。LINC00243通过靶向调控miR-1976促进甲状腺癌细胞增殖、迁移和侵袭。     

Metastasis-associated MCL1 and P16 copy number alterations dictate resistance to vemurafenib in a BRAFV600E patient-derived papillary thyroid carcinoma preclinical model

BRAF^V600E mutation exerts an essential oncogenic function in many tumors, including papillary thyroid carcinoma (PTC). Although BRAF^V600E inhibitors are available, lack of response has been frequently observed. To study the mechanism underlying intrinsic resistance to the mutant BRAF^V600E selective inhibitor vemurafenib, we established short-term primary cell cultures of human metastatic/recurrent BRAF^V600E-PTC, intrathyroidal BRAF^V600E-PTC, and normal thyroid (NT). We also generated an early intervention model of human BRAF^V600E-PTC orthotopic mouse. We find that metastatic BRAF^V600E-PTC cells elicit paracrine-signaling which trigger migration of pericytes, blood endothelial cells and lymphatic endothelial cells as compared to BRAF^WT-PTC cells, and show a higher rate of invasion. We further show that vemurafenib therapy significantly suppresses these aberrant functions in non-metastatic BRAF^V600E-PTC cells but lesser in metastatic BRAF^V600E-PTC cells as compared to vehicle treatment. These results concur with similar folds of down-regulation of tumor microenvironment–associated pro-metastatic molecules, with no effects in BRAF^WT-PTC and NT cells. Our early intervention preclinical trial shows that vemurafenib delays tumor growth in the orthotopic BRAF^WT/V600E-PTC mice. Importantly, we identify high copy number gain of MCL1 (chromosome 1q) and loss of CDKN2A (P16, chromosome 9p) in metastatic BRAF^V600E-PTC cells which are associated with resistance to vemurafenib treatment. Critically, we demonstrate that combined vemurafenib therapy with BCL2/MCL1 inhibitor increases metastatic BRAF^V600E-PTC cell death and ameliorates response to vemurafenib treatment as compared to single agent treatment. In conclusion, short-term PTC and NT cultures offer a predictive model for evaluating therapeutic response in patients with PTC. Our PTC pre-clinical model suggests that combined targeted therapy might be an important therapeutic strategy for metastatic and refractory BRAF^V600E-positive PTC.     

LncRNA LINC00958通过靶向miR-490-3p促进甲状腺乳头状癌细胞的增殖、侵袭和迁移

目的:研究LncRNA LINC00958对甲状腺乳头状癌细胞的影响及其作用机制。方法:TPC-1和K-1细胞分别分成Control、shRNA-NC、shRNA-LINC00958-1、shRNA-NC+inhibitor-NC、shRNA-LINC00958-1+inhibitor-NC和shRNA-LINC00958-1+miR-490-3p inhibitor组。TPC-1和K-1细胞移植的荷瘤鼠分别分为shRNA-NC、shRNA-LINC00958-1、shRNA-NC+inhibitor-NC、shRNA-LINC00958-1+inhibitor-NC和shRNA-LINC00958-1+miR-490-3p inhibitor组。用实时荧光定量PCR(RT-qPCR)检测LINC00958和miR-490-3p的表达水平;CCK-8检测细胞活力;Western blot检测蛋白表达水平;细胞划痕实验检测细胞迁移水平,Transwell小室检测细胞侵袭水平,克隆形成实验检测细胞增殖水平;双荧光素酶报告实验检测LINC00958和miR-490-3p的靶向关系。测定肿瘤质量及体积。结果:相比于正常组织,LINC00958在甲状腺癌组织中高表达;相比于Nthy-ori 3-1细胞,LINC00958在TPC-1和K-1细胞中高表达,miR-490-3p低表达。LINC00958沉默后,甲状腺乳头状癌细胞的增殖、侵袭和迁移能力显著降低。干扰miR-490-3p表达逆转LINC00958沉默对甲状腺乳头状癌细胞的增殖、迁移和侵袭效果,破坏LINC00958沉默对肿瘤生长的抑制效果。结论:抑制LINC00958表达可抑制TPC-1和K-1细胞增殖、迁移和侵袭能力,其机制与靶向miR-490-3p表达有关。     

SIRT1 promotes proliferation and inhibits the senescence-like phenotype in human melanoma cells

SIRT1 operates as both a tumor suppressor and oncogenic factor depending on the cell context. Whether SIRT1 plays a role in melanoma biology remained poorly elucidated. Here, we demonstrate that SIRT1 is a critical regulator of melanoma cell proliferation. SIRT1 suppression by genetic or pharmacological approaches induces cell cycle arrest and a senescence-like phenotype. Gain and loss of function experiments show that M-MITF regulates SIRT1 expression, thereby revealing a melanocyte-specific control of SIRT1. SIRT1 over-expression relieves the senescence-like phenotype and the proliferation arrest caused by MITF suppression, demonstrating that SIRT1 is an effector of MITF-induced proliferation in melanoma cells. Interestingly, SIRT1 level and activity are enhanced in the PLX4032-resistant BRAF^V600E-mutated melanoma cells compared with their sensitive counterpart. SIRT1 inhibition decreases melanoma cell growth and rescues the sensibility to PLX4032 of PLX4032-resistant BRAF^V600E-mutated melanoma cells. In conclusion, we provide the first evidence that inhibition of SIRT1 warrants consideration as an anti-melanoma therapeutic option.     

BRAF(V600E) and microenvironment in thyroid cancer: a functional link to drive cancer progression

Papillary thyroid cancer (PTC) rates continue to increase in the United States and Europe, and, although most patients do well, some recur and die of their disease. Patients with PTC harboring the BRAF(V600E) mutation seem to display a more aggressive clinical behavior, but little is known about the role of this mutation in crucial processes in the tumor microenvironment, such as tumor adhesion, migration, invasion, and metastasis. The extracellular matrix (ECM) microenvironment is not merely a structural scaffold for the cellular elements of the epithelial and stromal microenvironment, but it also elicits a profound influence on cell behavior affecting viability, proliferation, adhesion, and motility. The effects of BRAF(V600E) on cell surface receptors (i.e., integrins) and ECM noncellular components [i.e., thrombospondin-1 (TSP-1) and fibronectin (FN)] seem to trigger different pathologic biological processes in a cell context-dependent manner. This review focuses on the recent progress in understanding the role of BRAF(V600E) in the regulation of some ECM noncellular components and trans-membrane receptors of the microenvironment in PTC in order to design novel targeted therapies directed at the BRAF(V600E) multifaceted signaling cascades. Some of these targeted therapeutics, such as ATP-competitive BRAF(V600E) inhibitors (i.e., orally bioavailable PLX4720 and PLX4032 compounds), are already under investigation.     

Na+/K+-ATPase β2-subunit (AMOG) expression abrogates invasion of glioblastoma-derived brain tumor-initiating cells

Background

Mechanisms of glioma invasion remain to be fully elucidated. Glioma cells within glioblastoma multiforme (GBM) range from well-differentiated tumor cells to less-differentiated brain tumor-initiating cells (BTICs). The β2-subunit of Na⁺/K⁺-ATPase, called the adhesion molecule on glia (AMOG), is highly expressed in normal glia but is thought to be universally downregulated in GBM. To test our hypothesis that expression of AMOG is heterogeneous in GBM and confers a less invasive phenotype, we compared it between BTICs and differentiated cells from patient-matched GBM and then tested GBM invasion in vitro after AMOG overexpression.

Methods

Immunohistochemistry, immunoblotting, and real-time PCR were used to characterize AMOG protein and mRNA expression in tumor samples, BTICs, and differentiated cells. Matrigel invasion assay, scratch assay, and direct cell counting were used for testing in vitro invasion, migration, and proliferation, respectively.

Results

While AMOG expression is heterogeneous in astrocytomas of grades II–IV, it is lost in most GBM. BTICs express higher levels of AMOG mRNA and protein compared with patient-matched differentiated tumor cells. Overexpression of AMOG decreased GBM cell and BTIC invasion without affecting migration or proliferation. Knockdown of AMOG expression in normal human astrocytes increased invasion.

Conclusions

AMOG expression inhibits GBM invasion. Its downregulation increases invasion in glial cells and may also represent an important step in BTIC differentiation. These data provide compelling evidence implicating the role of AMOG in glioma invasion and provide impetus for further investigation.