Next-generation sequence detects ARAP3 as a novel oncogene in papillary thyroid carcinoma

OncoTargets and Therapy, Nov 2016

Next-generation sequence detects ARAP3 as a novel oncogene in papillary thyroid carcinoma Qing-Xuan Wang, En-Dong Chen, Ye-Feng Cai, Yi-Li Zhou, Zhou-Ci Zheng, Ying-Hao Wang, Yi-Xiang Jin, Wen-Xu Jin, Xiao-Hua Zhang, Ou-Chen Wang Department of Oncology, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang Province, China Purpose: Thyroid cancer is the most frequent malignancies of the endocrine system, and it has became the fastest growing type of cancer worldwide. Much still remains unknown about the molecular mechanisms of thyroid cancer. Studies have found that some certain relationship between ARAP3 and human cancer. However, the role of ARAP3 in thyroid cancer has not been well explained. This study aimed to investigate the role of ARAP3 gene in papillary thyroid carcinoma. Methods: Whole exon sequence and whole genome sequence of primary papillary thyroid carcinoma (PTC) samples and matched adjacent normal thyroid tissue samples were performed and then bioinformatics analysis was carried out. PTC cell lines (TPC1, BCPAP, and KTC-1) with transfection of small interfering RNA were used to investigate the functions of ARAP3 gene, including cell proliferation assay, colony formation assay, migration assay, and invasion assay. Results: Using next-generation sequence and bioinformatics analysis, we found ARAP3 genes may play an important role in thyroid cancer. Downregulation of ARAP3 significantly suppressed PTC cell lines (TPC1, BCPAP, and KTC-1), cell proliferation, colony formation, migration, and invasion. Conclusion: This study indicated that ARAP3 genes have important biological implications and may act as a potentially drugable target in PTC. Keywords: papillary thyroid carcinoma, next-generation sequence, ARAP3, oncogene

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Next-generation sequence detects ARAP3 as a novel oncogene in papillary thyroid carcinoma

OncoTargets and Therapy next-generation sequence detects ARAP3 as a novel oncogene in papillary thyroid carcinoma 0 Department of Oncology, The First a ffiliated h ospital of Wenzhou Medical University , Wenzhou, Zhejiang Province, china 8 1 0 2 - l u J - 2 1 n o 2 3 1 . 8 4 . 2 3 . 3 1 2 y b / m o c . s s rvpee l.yno PowerdbyTCPDF(ww.tcpdf.org) O r i g i n a l r e s e a r c h Purpose: Thyroid cancer is the most frequent malignancies of the endocrine system, and it has became the fastest growing type of cancer worldwide. Much still remains unknown about the molecular mechanisms of thyroid cancer. Studies have found that some certain relationship between ARAP3 and human cancer. However, the role of ARAP3 in thyroid cancer has not been well explained. This study aimed to investigate the role of ARAP3 gene in papillary thyroid carcinoma. Methods: Whole exon sequence and whole genome sequence of primary papillary thyroid carcinoma (PTC) samples and matched adjacent normal thyroid tissue samples were performed and then bioinformatics analysis was carried out. PTC cell lines (TPC1, BCPAP, and KTC-1) with transfection of small interfering RNA were used to investigate the functions of ARAP3 gene, including cell proliferation assay, colony formation assay, migration assay, and invasion assay. Results: Using next-generation sequence and bioinformatics analysis, we found ARAP3 genes may play an important role in thyroid cancer. Downregulation of ARAP3 significantly suppressed PTC cell lines (TPC1, BCPAP, and KTC-1), cell proliferation, colony formation, migration, and invasion. Conclusion: This study indicated that ARAP3 genes have important biological implications and may act as a potentially drugable target in PTC. - tissue samples and matched adjacent normal thyroid tissue samples and whole genome sequence of 10 primary PTC tissue samples and matched adjacent normal thyroid tissue samples. We then identified ARAP3 gene may act as a novel tumor oncogene in PTC. ARAP3 (ArfGAP with RhoGAP domain, ankyrin repeat, and PH domain 3) encodes a phosphoinositide8 binding protein containing ARF-GAP, RHO-GAP, RAS-021 associating, and pleckstrin homology domains. ARAP3 was l-Ju first identified for its ability to bind to phosphatidylinositol 12n ( 3,4,5 )-triphosphate in porcine leukocytes.15 ARAP3, on 32o activation of PI3K signaling, is found to be recruited to the .841 plasma membrane, regulating lamellipodia formation and ..32 growth factor signaling.15,16 Song et al revealed that ARAP3 321 minimally impacts hematopoietic stem cells in adult bone /yb marrow despite its critical role in embryonic vascular devel.com opment.17 Several studies have found that ARAP3 gene has ss certain relations with human cancers. Yagi et al found that rvpee l.yno ARAP3 inhibits peritoneal dissemination of scirrhous gastric .dow lsue carcinoma cells by regulating cell adhesion and invasion.18 //ww noa However, whether ARAP3 gene also plays an important role ttsp rspe in PTC is still unknown. : h ro Although studies have found that some certain relationfrom F ship between ARAP3 and human cancer, the role of ARAP3 aded in thyroid cancer has not been well explained. In this study, lno by performing next-generation sequence and bioinformatdow ics analysis, we found that ARAP3 gene may also play an rypa important role in thyroid cancer, which has not been reported ehT before. This study aims to investigate the real role of ARAP3 nad gene in PTC. s t e g r a T o c n O Materials and methods Patients and tissue collection Primary PTC samples and matched adjacent normal thyroid tissue samples were obtained at the time of initial surgery. Samples were snap-frozen in liquid nitrogen immediately after surgical resection and subsequently stored at a −80°C freezer. Histopathological slides were reviewed retrospectively for all cases to confirm the histological diagnosis and to ensure abundant cancer content of the tumor by two pathologists. All procedures performed in studies involving human participants were in accordance with the ethical standards of the Ethics Committee of the First Affiliated Hospital of Wenzhou Medical University. Informed consent for the scientific use of biological material was obtained from each patient. cell lines and cell culture The TPC1 and BCPAP cell lines were kindly provided by Professor Mingzhao Xing of the Johns Hopkins University 7162 School of Medicine, Baltimore, MA, USA. KTC-1 cell line was kindly provided by Stem Cell Bank, Chinese Academy of Sciences. The TPC1 and BCPAP were cultured in RPMI1640 supplemented with 10% fetal bovine serum and 1× MEM nonessential amino acids +1× sodium pyruvate. The KTC-1 was cultured in RPMI1640 supplemented with 10% fetal bovine serum and 1× MEM nonessential amino acids. All cell lines were incubated at 37°C in a humidified atmosphere containing 5% CO2. rna isolation and real-time reverse transcription-polymerase chain reaction Total RNA was isolated using TRIZOL Reagent (Invitrogen) and reverse transcription (Toyobo, Osaka, Japan) was performed according to the manufacturer’s instructions. Real-time PCR analysis was performed in triplicate on the ABI prism 7300 sequence detection system (Applied Biosystems, USA) using the THUNDERBIRD SYBR qPCR Mix (Toyobo) according to manufacturer’s instructions. The GAPDH mRNA level was used for normalization. Primer sequences were as follows: ARAP3: 5′-GTGGCTGGCTAGACAAGCTC-3′ (forward) and 5′-TCCTCCCATTGAACTGCACAA-3′ (reverse); GAPDH: 5′-GGTCGGAGTCAACGGATTTG-3′ (forward); and 5′-ATGAGCCCCAGCCTTCTCCAT-3′ (reverse). Protein extraction and Western blot analysis Treated cells were lysed in RIPA lysis buffer (Beyotime, Shanghai, China). An equal amount of protein of about 20 μg was separated by sodium dodecyl sulfate polyacrylamide gel electrophoresis and transferred onto the polyvinylidene fluoride membrane. After blocking with 5% skimmed milk, the polyvinylidene fluoride membrane was incubated with anti-ARAP3 antibody (Abcam, USA). After washing three times with tris-buffered saline and Tween 20, the membrane was incubated with horseradish peroxidase-linked secondary anti-goat immunoglobulin G antibody (Abcam) at room temperature for 1.5 h. GAPDH protein, detected using an anti-GAPDH antibody (Abcam), was used for control. rna interference Small interfering RNA (siRNA) for ARAP3 was purchased from Shanghai Gene Pharma (Shanghai, China) for siRNAmediated gene knockdown, 8×104 (TPC1) or 2×105 cells (BCPAP, KTC-1) were transfected with 10 μL (TPC1) or 7.5 μL (KTC-1) or 5 μL (BCPAP) siRNA (20 μM) and 4 μL RNAiMAX (Life Technologies, Carlsbad, CA, USA) in a 6-well plate according to the manufacturer’s 8 1 0 2 l u J 2 1 n o 2 3 1 . 8 4 . 2 3 . 3 1 2 y b / m o c . s s rvpee l.yno .dow lsue w a /w no :/s rs ttp pe h ro from F d e d a o l n w o d y p a r e h T d n a s t e g r a T o c n O recommendations. Cells were harvested 48 h after transfection for subsequent protein or RNA expression analysis. cell proliferation assay and colony formation assay For the proliferation assay, TPC1, KTC-1 cells (3×103 cells) and BCPAP cells (5×103 cells) were seeded in 96-well plates and then transfected with siRNA. All cells were then incubated at 37°C for consecutive 5 days. MTS (Solution Cell Proliferation Assay; Promega, Fitchburg, WI, USA) was added to the cells and, following a 2-h incubation, absorbance was measured at 490 nm using Spectramax M5 (Molecular Devices, Sunnyvale, CA, USA). For the colony forming assay, the three transfectant cells or control cells (2×103 cells for TPC1 and KTC-1, 4×103 cells for BCPAP) were seeded in 6-well plates, incubated for 8–14 days and then fixated with 4% PFA (paraformaldehyde; Sigma, USA) for 30 min and stained with 0.01% crystal violet for 30 min. All assays were performed in triplicate. Migration and invasion assays To detect the changed capacity of tumor cell migration, transwell cell culture chambers were used, according to the manufacturer’s instructions (Corning Costar Corp, Cambridge, MA, USA). The three transfectant cells or control cells (5×104 cells) were seeded in the upper chamber and the lower chamber was filled with culture medium supplemented with 10% fetal bovine serum. The cells were then incubated at 37°C in a humidified incubator in 5% CO2 for 24 h. Cells that did not traverse the filter were wiped off. Migrating cells on the reverse side of the filter were fixated with 4% PFA (Sigma) for 30 min and stained with 0.01% crystal violet for 30 min, and photographed under light microscope. To detect the changed capacity of tumor cell invasion, transwell cell culture chambers were used, according to the manufacturer’s instructions (Corning Costar Corp). The three transfectant cells or control cells (1×105 cells for TPC1, 2×105 cells for BCPAP and KTC-1) were seeded in the upper chamber and the lower chamber was filled with culture medium supplemented with 20% fetal bovine serum. The cells were then incubated at 37°C in a humidified incubator in 5% CO2 for 24 h. Cells that did not traverse the filter were wiped off. Cells on the reverse side of the filter were fixated with 4% PFA (Sigma) for 30 min and stained with 0.01% crystal violet for 30 min, and photographed under light microscope. statistical analysis Data on normal distribution were expressed as mean ± standard deviation and were compared with t-test. Categorical variables were expressed as percentage and were compared with chi-square test or Fisher’s exact test, as appropriate. All P-values were two sided, and a P-value of 0.05 was considered statistically significant. Statistical analysis was performed with SPSS software version 19.0 (SPSS, Chicago, IL, USA). GraphPad Prism 5 (GraphPad Software, La Jolla, CA, USA) was used for graphs. Results ARAP3 mutation was all found in patients without BraF V600e mutation We performed whole exon sequence of 65 paired PTC tissue samples and whole genome sequence of 10 paired PTC tissue samples. Among all the 75 patients (38 patients are BRAF V600E positive and 37 patients are BRAF V600E negative), ARAP3 mutation (141052399) was found in 4 patients without BRAF V600E mutation. None was found in patients with BRAF V600E mutation. A recurrence mutation (141052399) in 4 of all the 75 patients was identified. The detailed information of ARAP3 mutation (141052399) detected by nextgeneration sequence is shown in Table 1. The mutation rate was low in these four patients, with 11.76%, 13.04%, 12.5%, 11.54%, respectively. ARAP3 downregulation suppressed TPc1, BcP aP, and KTc-1 cell proliferation and colony formation To determine whether ARAP3 really plays an oncogenic role in thyroid cancer, we downregulated the gene expression level of ARAP3 by using siRNA. As shown in Figure 1, ARAP3 mRNA expression was effectively downregulated in both RNA and protein level. Then we carried out cell proliferation assays and colony formation assays in three PTC cell lines submit your manuscript | www.dovepress.com Dovepress 7163 8 1 0 2 l u J 2 1 n o 2 3 1 . 8 4 . 2 3 . 3 1 2 y b / m o c . s s rvpee l.yno ARAP3 downregulation inhibited TPc1, BcP aP, and KTc-1 migration and invasion Next, to investigate the role of ARAP3 in the migratory and invasive abilities of thyroid cancer cell lines (TPC1, BCPAP, and KTC-1), we carried out the migration and transwell invasion assays. The migration assays showed that it was significantly reduced in ARAP3 downregulation groups (S1 and S2) compared with the control cells (NC) (Figure 3). All three cell lines (TPC1, BCPAP, and KTC-1) transfected with siRNA migrated much less cells than the control cells after 24 h seeding (Figure 3, P0.05). It was more distinct in TPC1 and BCPAP than KTC-1. The transwell invasion assays also showed a similar result that ARAP3 downregulation significantly inhibited invasive capacity of three thyroid cancer cell lines (TPC1, BCPAP, and KTC-1). As shown in Figure 4, an obvious decrease in the number of invading cells between cell lines transfected with siRNA and the control cells (P0.05). These together indicated ARAP3 gene as a significant oncogene involving in tumorigenesis metastasis in PTC. Discussion Although much progress in genetic research had been made for thyroid cancer, much still remains unknown about the molecular mechanisms of PTC. There are still more than 4% PTC cases with unknown oncogenic driver and many epigenetic alterations have not yet been well studied.19 Using 8 1 0 2 l u J 2 1 n o 2 3 1 . 8 4 . 2 3 . 3 1 2 y b / m o c . s s rvpee l.yno .dow lsue w a /w no / :s rs ttp pe h ro om F fr d e d a o l n w o d y p a r e h T d n a s t e g r a T o c n O whole exon sequence and whole genome sequence, ARAP3 gene was found to may be act as an important oncogenic role in PTC. Some studies have demonstrated that ARAP3 gene was associated with human diseases such as embryonic vascular development and gastric cancer. ARAP3 gene were previously found to inhibit peritoneal dissemination of scirrhous gastric carcinoma cells by regulating cell adhesion and invasion.18 However, little is known about its function in human cancer especially thyroid cancer. In this study, the aim was to investigate the potential tumorigenic role of ARAP3 gene in thyroid cancer. Using whole exon sequence and whole genome sequence, a recurrence mutation (141052399) was found in 4 of all the 75 patients in ARAP3 gene. Moreover, it was missense mutation and amino submit your manuscript | www.dovepress.com Dovepress 7165 8 1 0 2 l u J 2 1 n o 2 3 1 . 8 4 . 2 3 . 3 1 2 y b / m o c . s s rvpee l.yno .dow lsue om F fr d e d a o l n w o d y p a r e h T d n a s t e g r a T o c n O ings suggest that ARAP3 may play a critical role in thyroid w a ://sw rsno cancer and prompted us to take the next step to functionally ttp pe study the ARAP3 gene in cell lines. Therefore, three thyroid h ro cancer cell lines, TPC1, BCPAP, and KTC-1, were chosen as cellular models for PTC. Then, using cellular and molecular approaches, ARAP3 downregulation was shown to lead to the inhibition of the ability of cell proliferation and the ability of migration and invasion, which are all well consistent with ARAP3 being a tumorigenic role in thyroid cancer. However, this study has some limitations. First, this study has not yet confirmed the existence of aforementioned point mutation detected by next-generation sequence. Conventional methods such as Sanger sequence were not sensitive enough to detected the mutation, because the rate of mutation bases is too low (Table 1). More sensitive methods need to be explored. Second, our study did not analysis relationship between clinicopathologic features and ARAP3 gene mutation and expression, such as lymph node metastasis and disease-free survival. Third, the specific mechanisms involved in the tumorigenic role of ARAP3 and whether there is epigenetic alteration in the ARAP3 gene in thyroid cancer still remains to be investigated. All in all, in this study, by using high-throughput sequence, bioinformatics analysis, and cellular and molecular approaches, exertion of ARAP3 gene as a tumorigenic role in PTC was demonstrated, particularly in proliferation and tumor metastasis, which add to our understanding of the molecular pathogenesis of PTC. This study indicated that submit your manuscript | www.dovepress.com Dovepress acid was located in one of the protein domains. These findARAP3 gene has important biological implications and may act as a potentially drugable target in PTC. Acknowledgments The authors acknowledge Chuan-Meng Pan who helped to perform statistical analysis. This work was supported by a grant from the National High Technology Research and Development Program of 863 project of China (NO 2012AA02A210) and Major Science and Technology Projects of Zhejian Province (2015C03052). Disclosure References The authors report no conflicts of interest in this work. 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Qing-Xuan Wang, En-Dong Chen, Ye-Feng Cai, Yi-Li Zhou, Zhou-Ci Zheng, Ying-Hao Wang, Yi-Xiang Jin, Wen-Xu Jin, Xiao-Hua Zhang, Ou-Chen Wang. Next-generation sequence detects ARAP3 as a novel oncogene in papillary thyroid carcinoma, OncoTargets and Therapy, 2016, 7161-7167, DOI: 10.2147/OTT.S115668