患有第二型糖尿病的病人會有胰島素抗性的現象導致體內胰島素濃度為因應胰島素阻抗而增加，伴隨著罹癌的風險也提升。因此，本文欲探討第二型糖尿病的病人所誘導的高濃度胰島素是透過何種機制造成細胞癌化。本文指出，胰島素會誘導肝癌HepG2及乳癌MCF7細胞中致癌基因c-Myc以及脂質合成相關酵素如固醇調節區域結合蛋白1(SREBP1)及乙醯輔酶A羧化酶(ACC1)的蛋白質與訊息RNA的表現量增加。此外，我們指出在胰島素的誘導下，經由胸腺嘧啶DNA糖化酶(TDG)所引起的表觀遺傳調控，使得固醇調節區域結合蛋白1啟動子的甲基化程度下降，造成其表現量增加，進而促進乙醯輔酶A羧化酶之轉錄。我們認為，胰島素將透過增加脂質合成而促使癌細胞的增生。另一項有趣的發現是胰島素也會誘導肝癌HepG2及乳癌MCF7細胞中的麩醯胺酸合成酶(GS)增加，麩醯胺酸合成酶能夠將麩胺酸催化成麩醯胺酸，在肝癌HepG2及乳癌MCF7細胞中過度表達麩醯胺酸合成酶雖然會抑制細胞在營養充足的環境下的生長，但卻能幫助肝癌HepG2細胞較能存活在麩醯胺酸缺乏的環境中，推測麩醯胺酸合成酶產生之麩醯胺酸可以幫助細胞生長在資源相對不足的環境中。透過本文，我們將連結因第二型糖尿病所引起的高胰島素與脂質合成、麩醯胺酸代謝和癌細胞增生之間的關係。

Patients with type II diabetes suffer from hyperinsulinemia-induced insulin resistance which associates with higher risk of getting cancers. Therefore, we are interested in investigating the mechanisms how cancer development is triggered owing to hyperinsulinemia. Here we report that insulin upregulates the oncoprotein c-Myc and lipogenic enzymes such as sterol regulatory element binding protein 1 (SREBP1) and acetyl-CoA carboxylase 1 (ACC1) on both mRNA and protein levels in liver cancer HepG2 cells and breast cancer MCF7 cells. In addition, we suggest that the epigenetic regulation is involved in modulating the expression of SREBP1, the transcription factor of ACC1, by the DNA demethylase thymine DNA glycosylase (TDG) with insulin treatment, therefore, resulting in enhanced ACC1 transcription. High level of insulin is thought of as leading to cancer cell proliferation which may be attributed to upregulated lipogenesis. Intriguingly, we also reveal a novel finding that glutamine synthetase (GS), converting glutamate to glutamine, is upregulated by insulin in HepG2 cells and MCF7 cells under insulin effects. Overexpression of GS reduces HepG2 cells and MCF7 cells proliferation but increases the cell survival in glutamine deficient environment due to higher intracellular glutamine synthesis catalyzed by GS. This study will link type II diabetes-induced hyperinsulinemia, lipogenesis, glutamine metabolism and cancer cell proliferation.

Akinyeke, T., Matsumura, S., Wang, X., Wu, Y., Schalfer, E.D., Saxena, A., Yan, W., Logan, S.K., and Li, X. (2013). Metformin targets c-MYC oncogene to prevent prostate cancer. Carcinogenesis 34, 2823-2832.
Alfano, D., Votta, G., Schulze, A., Downward, J., Caputi, M., Stoppelli, M.P., and Iaccarino, I. (2010). Modulation of cellular migration and survival by c-Myc through the downregulation of urokinase (uPA) and uPA receptor. Molecular and cellular biology 30, 1838-1851.
Bandyopadhyay, S., Pai, S.K., Watabe, M., Gross, S.C., Hirota, S., Hosobe, S., Tsukada, T., Miura, K., Saito, K., and Markwell, S.J. (2005). FAS expression inversely correlates with PTEN level in prostate cancer and a PI 3-kinase inhibitor synergizes with FAS siRNA to induce apoptosis. Oncogene 24, 5389-5395.
Belfiore, A., and Malaguarnera, R. (2011). The insulin receptor and cancer. Endocrine-related cancer, ERC-11-0074.
Beloribi-Djefaflia, S., Vasseur, S., and Guillaumond, F. (2016). Lipid metabolic reprogramming in cancer cells. Oncogenesis 5, e189.
Bhutani, N., Burns, D.M., and Blau, H.M. (2011). DNA demethylation dynamics. Cell 146, 866-872.
Bott, A.J., Peng, I.-C., Fan, Y., Faubert, B., Zhao, L., Li, J., Neidler, S., Sun, Y., Jaber, N., and Krokowski, D. (2015). Oncogenic Myc induces expression of glutamine synthetase through promoter demethylation. Cell metabolism 22, 1068-1077.
Boyd, D.B. (2003). Insulin and cancer. Integrative cancer therapies 2, 315-329.
Brown, M.S., and Goldstein, J.L. (1997). The SREBP pathway: regulation of cholesterol metabolism by proteolysis of a membrane-bound transcription factor. Cell 89, 331-340.
Camarda, R., Zhou, A.Y., Kohnz, R.A., Balakrishnan, S., Mahieu, C., Anderton, B., Eyob, H., Kajimura, S., Tward, A., and Krings, G. (2016). Inhibition of fatty acid oxidation as a therapy for MYC-overexpressing triple-negative breast cancer. Nature medicine 22, 427.
Carracedo, A., Cantley, L.C., and Pandolfi, P.P. (2013). Cancer metabolism: fatty acid oxidation in the limelight. Nature reviews Cancer 13, 227.
Castegna, A., and Menga, A. (2018). Glutamine synthetase: Localization dictates outcome. Genes 9, 108.
Cho, K.B., Cho, M.K., Lee, W.Y., and Kang, K.W. (2010). Overexpression of c-myc induces epithelial mesenchymal transition in mammary epithelial cells. Cancer letters 293, 230-239.
Cluntun, A.A., Lukey, M.J., Cerione, R.A., and Locasale, J.W. (2017). Glutamine metabolism in cancer: understanding the heterogeneity. Trends in cancer 3, 169-180.
Csibi, A., Lee, G., Yoon, S.-O., Tong, H., Ilter, D., Elia, I., Fendt, S.-M., Roberts, T.M., and Blenis, J. (2014). The mTORC1/S6K1 pathway regulates glutamine metabolism through the eIF4B-dependent control of c-Myc translation. Current Biology 24, 2274-2280.
Dai, L., Qi, Y., Chen, J., Kaczorowski, D., Di, W., Wang, W., and Xia, P. (2014). Sphingosine kinase (SphK) 1 and SphK2 play equivalent roles in mediating insulin's mitogenic action. Molecular Endocrinology 28, 197-207.
Dang, C.V. (2012). MYC on the path to cancer. Cell 149, 22-35.
Dubik, D., and Shiu, R. (1992). Mechanism of estrogen activation of c-myc oncogene expression. Oncogene 7, 1587-1594.
Edmunds, L.R., Sharma, L., Kang, A., Lu, J., Vockley, J., Basu, S., Uppala, R., Goetzman, E.S., Beck, M.E., and Scott, D. (2014a). c-Myc programs fatty acid metabolism and dictates acetyl-CoA abundance and fate. Journal of Biological Chemistry 289, 25382-25392.
Edmunds, L.R., Sharma, L., Kang, A., Lu, J., Vockley, J., Basu, S., Uppala, R., Goetzman, E.S., Beck, M.E., and Scott, D. (2014b). c-Myc programs fatty acid metabolism and dictates acetyl CoA abundance and fate. Journal of Biological Chemistry, jbc. M114. 580662.
Esechie, A., and Du, G. (2009). Increased lipogenesis in cancer. Communicative & Integrative Biology 2, 545-548.
Ferrari, A., Fiorino, E., Giudici, M., Gilardi, F., Galmozzi, A., Mitro, N., Cermenati, G., Godio, C., Caruso, D., and De Fabiani, E. (2012). Linking epigenetics to lipid metabolism: focus on histone deacetylases. Molecular membrane biology 29, 257-266.
Furusawa, A., Miyamoto, M., Takano, M., Tsuda, H., Song, Y.S., Aoki, D., Miyasaka, N., Inazawa, J., and Inoue, J. (2018). Ovarian cancer therapeutic potential of glutamine depletion based on GS expression. Carcinogenesis 39, 758-766.
Gao, P., Tchernyshyov, I., Chang, T.-C., Lee, Y.-S., Kita, K., Ochi, T., Zeller, K.I., De Marzo, A.M., Van Eyk, J.E., and Mendell, J.T. (2009). c-Myc suppression of miR-23a/b enhances mitochondrial glutaminase expression and glutamine metabolism. Nature 458, 762.
Gilkes, D.M., Semenza, G.L., and Wirtz, D. (2014). Hypoxia and the extracellular matrix: drivers of tumour metastasis. Nature Reviews Cancer 14, 430.
Goetzman, E.S., and Prochownik, E.V. (2018). The Role for Myc in Coordinating Glycolysis, Oxidative Phosphorylation, Glutaminolysis, and Fatty Acid Metabolism in Normal and Neoplastic Tissues. Frontiers in endocrinology 9, 129.
Grunt, T.W. (2017). Interacting Cancer machineries: cell signaling, lipid metabolism, and epigenetics. Trends in Endocrinology & Metabolism.
Guil, S., and Esteller, M. (2009). DNA methylomes, histone codes and miRNAs: tying it all together. The international journal of biochemistry & cell biology 41, 87-95.
Guo, Y., Zhu, S.-l., Wu, Y.-k., He, Z., and Chen, Y.-q. (2017). Omega-3 free fatty acids attenuate insulin-promoted breast cancer cell proliferation. Nutrition Research 42, 43-50.
Haikala, H.M., Anttila, J.M., and Klefström, J. (2017). MYC and AMPK–Save Energy or Die! Frontiers in cell and developmental biology 5, 38.
Han, J., Li, E., Chen, L., Zhang, Y., Wei, F., Liu, J., Deng, H., and Wang, Y. (2015). The CREB coactivator CRTC2 controls hepatic lipid metabolism by regulating SREBP1. Nature 524, 243.
Hassan, H.M., Kolendowski, B., Isovic, M., Bose, K., Dranse, H.J., Sampaio, A.V., Underhill, T.M., and Torchia, J. (2017). Regulation of active DNA demethylation through RAR-mediated recruitment of a TET/TDG complex. Cell reports 19, 1685-1697.
He, Y.-F., Li, B.-Z., Li, Z., Liu, P., Wang, Y., Tang, Q., Ding, J., Jia, Y., Chen, Z., and Li, L. (2011). Tet-mediated formation of 5-carboxylcytosine and its excision by TDG in mammalian DNA. Science 333, 1303-1307.
Henry, R.A., Kuo, Y.-M., Bhattacharjee, V., Yen, T.J., and Andrews, A.J. (2014). Changing the selectivity of p300 by acetyl-CoA modulation of histone acetylation. ACS chemical biology 10, 146-156.
Henry, R.A., Mancuso, P., Kuo, Y.-M., Tricarico, R., Tini, M., Cole, P.A., Bellacosa, A., and Andrews, A.J. (2016). Interaction with the DNA Repair Protein Thymine DNA Glycosylase Regulates Histone Acetylation by p300. Biochemistry 55, 6766-6775.
Huang, M.-J., Cheng, Y.-c., Liu, C.-R., Lin, S., and Liu, H.E. (2006). A small-molecule c-Myc inhibitor, 10058-F4, induces cell-cycle arrest, apoptosis, and myeloid differentiation of human acute myeloid leukemia. Experimental hematology 34, 1480-1489.
Kitsera, N., Allgayer, J., Parsa, E., Geier, N., Rossa, M., Carell, T., and Khobta, A. (2017). Functional impacts of 5-hydroxymethylcytosine, 5-formylcytosine, and 5-carboxycytosine at a single hemi-modified CpG dinucleotide in a gene promoter. Nucleic acids research 45, 11033-11042.
Kung, H.-N., Marks, J.R., and Chi, J.-T. (2011). Glutamine synthetase is a genetic determinant of cell type–specific glutamine independence in breast epithelia. PLoS genetics 7, e1002229.
Lampa, M., Arlt, H., He, T., Ospina, B., Reeves, J., Zhang, B., Murtie, J., Deng, G., Barberis, C., and Hoffmann, D. (2017). Glutaminase is essential for the growth of triple-negative breast cancer cells with a deregulated glutamine metabolism pathway and its suppression synergizes with mTOR inhibition. PloS one 12, e0185092.
Lee, J.-S., Kang, J.H., Lee, S.-H., Lee, C.-H., Son, J., and Kim, S.-Y. (2016). Glutaminase 1 inhibition reduces thymidine synthesis in NSCLC. Biochemical and biophysical research communications 477, 374-382.
Lee, T., Yao, G., Nevins, J., and You, L. (2008). Sensing and integration of Erk and PI3K signals by Myc. PLoS computational biology 4, e1000013.
Li, Z., Gu, T.-P., Weber, A.R., Shen, J.-Z., Li, B.-Z., Xie, Z.-G., Yin, R., Guo, F., Liu, X., and Tang, F. (2015). Gadd45a promotes DNA demethylation through TDG. Nucleic acids research 43, 3986-3997.
Luo, X., Cheng, C., Tan, Z., Li, N., Tang, M., Yang, L., and Cao, Y. (2017). Emerging roles of lipid metabolism in cancer metastasis. Molecular cancer 16, 76.
Maiti, A., and Drohat, A.C. (2011). Thymine DNA glycosylase can rapidly excise 5-formylcytosine and 5-carboxylcytosine potential implications for active demethylation of CpG sites. Journal of Biological Chemistry 286, 35334-35338.
Masui, K., Tanaka, K., Akhavan, D., Babic, I., Gini, B., Matsutani, T., Iwanami, A., Liu, F., Villa, G.R., and Gu, Y. (2013). mTOR complex 2 controls glycolytic metabolism in glioblastoma through FoxO acetylation and upregulation of c-Myc. Cell metabolism 18, 726-739.
Matkar, S., Sharma, P., Gao, S., Gurung, B., Katona, B.W., Liao, J., Muhammad, A.B., Kong, X.-C., Wang, L., and Jin, G. (2015). An epigenetic pathway regulates sensitivity of breast cancer cells to HER2 inhibition via FOXO/c-Myc axis. Cancer cell 28, 472-485.
Morrish, F., Noonan, J., Perez-Olsen, C., Gafken, P.R., Fitzgibbon, M., Kelleher, J., VanGilst, M., and Hockenbery, D. (2010). Myc-dependent mitochondrial generation of acetyl-CoA contributes to fatty acid biosynthesis and histone acetylation during cell cycle entry. Journal of Biological Chemistry 285, 36267-36274.
Murata, M., Okimura, Y., Iida, K., Matsumoto, M., Sowa, H., Kaji, H., Kojima, M., Kangawa, K., and Chihara, K. (2002). Ghrelin modulates the downstream molecules of insulin signaling in hepatoma cells. Journal of Biological Chemistry 277, 5667-5674.
Niehrs, C., and Schäfer, A. (2012). Active DNA demethylation by Gadd45 and DNA repair. Trends in cell biology 22, 220-227.
Orgel, E., and Mittelman, S.D. (2013). The links between insulin resistance, diabetes, and cancer. Current diabetes reports 13, 213-222.
Pérez-Escuredo, J., Dadhich, R.K., Dhup, S., Cacace, A., Van Hée, V.F., De Saedeleer, C.J., Sboarina, M., Rodriguez, F., Fontenille, M.-J., and Brisson, L. (2016). Lactate promotes glutamine uptake and metabolism in oxidative cancer cells. Cell Cycle 15, 72-83.
Pelicano, H., Martin, D., Xu, R., and, and Huang, P. (2006). Glycolysis inhibition for anticancer treatment. Oncogene 25, 4633.
Perna, D., Faga, G., Verrecchia, A., Gorski, M., Barozzi, I., Narang, V., Khng, J., Lim, K., Sung, W., and Sanges, R. (2012). Genome-wide mapping of Myc binding and gene regulation in serum-stimulated fibroblasts. Oncogene 31, 1695.
Pivovarova, O., von Loeffelholz, C., Ilkavets, I., Sticht, C., Zhuk, S., Murahovschi, V., Lukowski, S., Döcke, S., Kriebel, J., and de las Heras Gala, T. (2015). Modulation of insulin degrading enzyme activity and liver cell proliferation. Cell Cycle 14, 2293-2300.
Ricoult, S., Yecies, J., Ben-Sahra, I., and Manning, B. (2016). Oncogenic PI3K and K-Ras stimulate de novo lipid synthesis through mTORC1 and SREBP. Oncogene 35, 1250-1260.
Rodrik, V., Zheng, Y., Harrow, F., Chen, Y., and Foster, D.A. (2005). Survival signals generated by estrogen and phospholipase D in MCF-7 breast cancer cells are dependent on Myc. Molecular and cellular biology 25, 7917-7925.
Roth, G., Kotzka, J., Kremer, L., Lehr, S., Lohaus, C., Meyer, H.E., Krone, W., and Müller-Wieland, D. (2000). MAP kinases Erk1/2 phosphorylate sterol regulatory element-binding protein (SREBP)-1a at serine 117 in vitro. Journal of Biological Chemistry 275, 33302-33307.
Sayols-Baixeras, S., Irvin, M.R., Elosua, R., Arnett, D.K., and Aslibekyan, S.W. (2016). Epigenetics of lipid phenotypes. Current cardiovascular risk reports 10, 31.
Schäfer, A., Schomacher, L., Barreto, G., Döderlein, G., and Niehrs, C. (2010). Gemcitabine functions epigenetically by inhibiting repair mediated DNA demethylation. PLoS One 5, e14060.
Shajahan-Haq, A.N., Cook, K.L., Schwartz-Roberts, J.L., Eltayeb, A.E., Demas, D.M., Warri, A.M., Facey, C.O., Hilakivi-Clarke, L.A., and Clarke, R. (2014). MYC regulates the unfolded protein response and glucose and glutamine uptake in endocrine resistant breast cancer. Molecular cancer 13, 239.
Shim, H., Dolde, C., Lewis, B.C., Wu, C.-S., Dang, G., Jungmann, R.A., Dalla-Favera, R., and Dang, C.V. (1997). c-Myc transactivation of LDH-A: implications for tumor metabolism and growth. Proceedings of the National Academy of Sciences 94, 6658-6663.
Shimomura, I., Shimano, H., Horton, J.D., Goldstein, J.L., and Brown, M.S. (1997). Differential expression of exons 1a and 1c in mRNAs for sterol regulatory element binding protein-1 in human and mouse organs and cultured cells. Journal of Clinical Investigation 99, 838.
Sohn, B.H., Park, I.Y., Shin, J.-H., Yim, S.Y., and Lee, J.-S. (2018). Glutamine synthetase mediates Sorafenib sensitivity in β-catenin-active hepatocellular carcinoma cells. Experimental & molecular medicine 50, e421.
Svensson, R.U., Parker, S.J., Eichner, L.J., Kolar, M.J., Wallace, M., Brun, S.N., Lombardo, P.S., Van Nostrand, J.L., Hutchins, A., and Vera, L. (2016). Inhibition of acetyl-CoA carboxylase suppresses fatty acid synthesis and tumor growth of non-small-cell lung cancer in preclinical models. Nature medicine 22, 1108.
Tang, J.-J., Li, J.-G., Qi, W., Qiu, W.-W., Li, P.-S., Li, B.-L., and Song, B.-L. (2011). Inhibition of SREBP by a small molecule, betulin, improves hyperlipidemia and insulin resistance and reduces atherosclerotic plaques. Cell metabolism 13, 44-56.
Tini, M., Benecke, A., Um, S.-J., Torchia, J., Evans, R.M., and Chambon, P. (2002). Association of CBP/p300 acetylase and thymine DNA glycosylase links DNA repair and transcription. Molecular cell 9, 265-277.
Valentine, R.J., Coughlan, K.A., Ruderman, N.B., and Saha, A.K. (2014). Insulin inhibits AMPK activity and phosphorylates AMPK Ser485/491 through Akt in hepatocytes, myotubes and incubated rat skeletal muscle. Archives of biochemistry and biophysics 562, 62-69.
Vigneri, P., Frasca, F., Sciacca, L., Pandini, G., and Vigneri, R. (2009). Diabetes and cancer. Endocrine-related cancer 16, 1103-1123.
Wairagu, P.M., Phan, A.N., Kim, M.-K., Han, J., Kim, H.-W., Choi, J.-W., Kim, K.W., Cha, S.-K., Park, K.H., and Jeong, Y. (2015). Insulin priming effect on estradiol-induced breast cancer metabolism and growth. Cancer biology & therapy 16, 484-492.
Wang, C., Xu, C., Sun, M., Luo, D., Liao, D.-f., and Cao, D. (2009). Acetyl-CoA carboxylase-α inhibitor TOFA induces human cancer cell apoptosis. Biochemical and biophysical research communications 385, 302-306.
Wang, C.C.L., Gurevich, I., and Draznin, B. (2003). Insulin affects vascular smooth muscle cell phenotype and migration via distinct signaling pathways. Diabetes 52, 2562-2569.
Wasylishen, A.R., Stojanova, A., Oliveri, S., Rust, A.C., Schimmer, A.D., and Penn, L.Z. (2011). New model systems provide insights into Myc-induced transformation. Oncogene 30, 3727.
Weber, A.R., Krawczyk, C., Robertson, A.B., Kuśnierczyk, A., Vågbø, C.B., Schuermann, D., Klungland, A., and Schär, P. (2016). Biochemical reconstitution of TET1–TDG–BER-dependent active DNA demethylation reveals a highly coordinated mechanism. Nature communications 7, 10806.
West, M.J., Stoneley, M., and Willis, A.E. (1998). Translational induction of the c-myc oncogene via activation of the FRAP/TOR signalling pathway. Oncogene 17, 769-780.
Wise, D.R., DeBerardinis, R.J., Mancuso, A., Sayed, N., Zhang, X.-Y., Pfeiffer, H.K., Nissim, I., Daikhin, E., Yudkoff, M., and McMahon, S.B. (2008). Myc regulates a transcriptional program that stimulates mitochondrial glutaminolysis and leads to glutamine addiction. Proceedings of the National Academy of Sciences 105, 18782-18787.
Yellaturu, C.R., Deng, X., Cagen, L.M., Wilcox, H.G., Mansbach, C.M., Siddiqi, S.A., Park, E.A., Raghow, R., and Elam, M.B. (2009). Insulin enhances post-translational processing of nascent SREBP-1c by promoting its phosphorylation and association with COPII vesicles. Journal of biological chemistry 284, 7518-7532.
Yuan, L., Sheng, X., Clark, L.H., Zhang, L., Guo, H., Jones, H.M., Willson, A.K., Gehrig, P.A., Zhou, C., and Bae-Jump, V.L. (2016). Glutaminase inhibitor compound 968 inhibits cell proliferation and sensitizes paclitaxel in ovarian cancer. American journal of translational research 8, 4265.
Yuneva, M.O., Fan, T.W., Allen, T.D., Higashi, R.M., Ferraris, D.V., Tsukamoto, T., Matés, J.M., Alonso, F.J., Wang, C., and Seo, Y. (2012). The metabolic profile of tumors depends on both the responsible genetic lesion and tissue type. Cell metabolism 15, 157-170.
Zhang, Y.W., Wang, Z., Xie, W., Cai, Y., Xia, L., Easwaran, H., Luo, J., Yen, R.-W.C., Li, Y., and Baylin, S.B. (2017). Acetylation enhances TET2 function in protecting against abnormal DNA methylation during oxidative stress. Molecular cell 65, 323-335.
Zhao, D., Fukuyama, S., Sakai-Tagawa, Y., Takashita, E., Shoemaker, J.E., and Kawaoka, Y. (2015). C646, a novel p300/CREB-binding protein-specific inhibitor of histone acetyltransferase, attenuates influenza A virus infection. Antimicrobial agents and chemotherapy, AAC. 02055-02015.
Zirath, H., Frenzel, A., Oliynyk, G., Segerström, L., Westermark, U.K., Larsson, K., Persson, M.M., Hultenby, K., Lehtiö, J., and Einvik, C. (2013). MYC inhibition induces metabolic changes leading to accumulation of lipid droplets in tumor cells. Proceedings of the National Academy of Sciences 110, 10258-10263.