口腔癌是全球十大最常見的癌症之一。鱗狀細胞癌（SCC）是口腔中最普遍的惡性腫瘤，佔口腔癌的90％以上。多胺與多種細胞功能有關，包括基因表達的調節，細胞週期的調控，核酸的維持和膜的穩定性。在哺乳動物的多胺代謝中，腐胺是合成代謝途徑中的第一個多胺，通過鳥氨酸脫羧酶1（ODC）催化鳥氨酸脫羧而產生的。再透過亞精胺氧化酶和精胺氧化酶的作用，將腐胺依次轉化為亞精胺和精胺。精胺氧化酶（spermine oxidase, SMOX）直接催化精胺氧化為亞精胺，並生成3-氨基丙醛和H2O2。先前文獻報導指出，H2O2的生成與DNA損傷和細胞凋亡有密切相關。在過去文獻中，發現精胺氧化酶的增加與乳腺癌、結腸癌、前列腺癌等癌症發生有關。但是在口腔癌上的研究，目前尚未有進一步的探討。因此在本次實驗中，我們主要探討精胺氧化酶在口腔鱗狀細胞癌和存在口腔黏膜纖維化的臨床病理組織中的表現差異。我們利用免疫組織染色分析口腔癌檢體和伴隨有口腔黏膜纖維化的口腔癌檢體，結果發現精胺氧化酶較高表現在口腔癌早期(原發腫瘤大小第一期,T1)和未有淋巴結轉移(N0)的癌細胞中，而且腫瘤發生在牙齦、口底、唇部有較高量精胺氧化酶。此外我們也發先精胺氧化酶通常較高量表現在腫瘤組織表面邊緣，我們猜測精胺氧化酶的表現可能受到口腔微生物的影響。我們先前研究發現鏈球菌Streptococcus anginosus在口腔癌前病變惡轉時會減少，因此，我們接著用西方墨點法去檢測加入鏈球菌後，口腔癌細胞株的精胺酸氧化酶的表現量是否受到影響。在結果顯示，加入鏈球菌處理2~6小時精胺酸氧化酶隨著處理時間增加，而加入熱處理失去活性的鏈球菌後，隨著處理時間改變會減少精胺氧化酶的表現。另外我們在口腔癌細胞中加入不同濃度的精胺氧化酶抑制劑MDL72527，去測試是否會影響口腔癌細胞的細胞增殖，結果顯示MDL72527明顯的抑制口腔癌細胞株的生長，而對纖維母細胞株影響較小。在此研究中，將了解精胺氧化酶在口腔癌癌化過程中所扮演的重要角色，未來提供作為口腔癌治療的參考與指標。

Oral squamous cell carcinoma (OSCC) is the most common malignant tumor in the oral cavity. Polyamine metabolism has been known to associate with tumor formation. Spermine oxidase (SMOX) is an important enzyme involved in polyamine metabolism, and related to the occurrence of breast cancer, colon cancer, prostate cancer and other cancers. However, the association of SMOX and oral cancer hasn't been explored yet. In this study, we mainly explored the role of SMOX in OSCC, and its clinicopathological correaltion. We analyzed the expression of SMOX in OSCC and OSCC with oral submucous fibrosis (OSF-OSCC) specimens by using immunohistochemistry. We found that the level of SMOX was higher in the early stage of oral cancer (tumor stage T1) and OSCC without lymph node metastasis (N0). High SMOX was found in the tumor cells located at the gums, the mouth floor, and the lips. In addition, we also found that SMOX was increased in the edge of the tumor tissues suggesting that the expression of SMOX may be affected by oral microbes. In our previous study found that the abundance of Streptococcus anginosus is decreased when oral precancerous lesions become malignant. Therefore, we then used the Western blotting to detect the expression of SMOX in oral cancer cell lines with S. anginosus treatment. The results showed that after 2-6 hours of treatment with S. anginosus, the SMOX of oral cancer cells time-dependently increased, while the inactivated S. anginosus reduced the SMOX of the cells. In addition, we added different concentrations of SMOX inhibitor (MDL72527) to oral cancer cells to test whether it affects the cell proliferation of oral cancer cells. The results show that MDL72527 significantly inhibited the growth of oral cancer cell lines, but it has no effect on fibroblast cell lines. In this study, understanding the role of SMOX involved in the carcinogenesis of oral cancer will help the oral cancer therapeutics in the future.

1 Siegel, R. L., Miller, K. D., Fuchs, H. E. & Jemal, A. Cancer Statistics, 2021. CA: A Cancer Journal for Clinicians 71, 7-33, doi:https://doi.org/10.3322/caac.21654 (2021).
2 Chow, L. Q. M. Head and Neck Cancer. N Engl J Med 382, 60-72, doi:10.1056/NEJMra1715715 (2020).
3 <【簡報檔】1090602健康署-公布106年癌症發生資料記者會 (1).pdf>.
4 Anwar, N. et al. Oral cancer: Clinicopathological features and associated risk factors in a high risk population presenting to a major tertiary care center in Pakistan. PLoS One 15, e0236359, doi:10.1371/journal.pone.0236359 (2020).
5 Shih, Y. H., Wang, T. H., Shieh, T. M. & Tseng, Y. H. Oral Submucous Fibrosis: A Review on Etiopathogenesis, Diagnosis, and Therapy. Int J Mol Sci 20, doi:10.3390/ijms20122940 (2019).
6 Chiang, P. K. et al. S-Adenosylmethionine and methylation. FASEB journal : official publication of the Federation of American Societies for Experimental Biology 10, 471-480 (1996).
7 Casero, R. A., Murray Stewart, T. & Pegg, A. E. Polyamine metabolism and cancer: treatments, challenges and opportunities. Nature Reviews Cancer 18, 681-695, doi:10.1038/s41568-018-0050-3 (2018).
8 Zhang, T. et al. Polyamine pathway activity promotes cysteine essentiality in cancer cells. Nature Metabolism 2, 1062-1076, doi:10.1038/s42255-020-0253-2 (2020).
9 Hu, X., Washington, S., Verderame, M. F. & Manni, A. Interaction between Polyamines and the Mitogen-Activated Protein Kinase Pathway in the Regulation of Cell Cycle Variables in Breast Cancer Cells. Cancer Res 65, 11026-11033, doi:10.1158/0008-5472.CAN-05-1339 (2005).
10 ALFARHAN, M., Liu, F., Pichavaram, P. & Narayanan, S. P. Pharmacological inhibition of spermine oxidase ameliorates neuroinflammation in a model of retinal excitotoxicity. Investigative Ophthalmology & Visual Science 62, 1155-1155 (2021).
11 Novita Sari, I. et al. Metabolism and function of polyamines in cancer progression. Cancer Lett 519, 91-104, doi:10.1016/j.canlet.2021.06.020 (2021).
12 Goodwin, A. C. et al. Polyamine catabolism contributes to enterotoxigenic Bacteroides fragilis-induced colon tumorigenesis. Proceedings of the National Academy of Sciences of the United States of America 108, 15354-15359, doi:10.1073/pnas.1010203108 (2011).
13 Murata, M., Noda, K. & Ishida, S. Pathological Role of Unsaturated Aldehyde Acrolein in Diabetic Retinopathy. Front Immunol 11, 589531, doi:10.3389/fimmu.2020.589531 (2020).
14 Xu, H. et al. Spermine Oxidation Induced by <strong><em>Helicobacter pylori</em></strong> Results in Apoptosis and DNA Damage. Implications for Gastric Carcinogenesis 64, 8521-8525, doi:10.1158/0008-5472.Can-04-3511 (2004).
15 Chaturvedi, R. et al. Activation of EGFR and ERBB2 by Helicobacter pylori results in survival of gastric epithelial cells with DNA damage. Gastroenterology 146, 1739-1751 e1714, doi:10.1053/j.gastro.2014.02.005 (2014).
16 Casero, R. A., Jr. & Marton, L. J. Targeting polyamine metabolism and function in cancer and other hyperproliferative diseases. Nat Rev Drug Discov 6, 373-390, doi:10.1038/nrd2243 (2007).
17 Chaturvedi, R. et al. Spermine oxidase is a regulator of macrophage host response to Helicobacter pylori: enhancement of antimicrobial nitric oxide generation by depletion of spermine. Amino Acids 46, 531-542, doi:10.1007/s00726-013-1531-z (2014).
18 Sasaki, M. et al. Streptococcus anginosus infection in oral cancer and its infection route. Oral Diseases 11, 151-156, doi:https://doi.org/10.1111/j.1601-0825.2005.01051.x (2005).
19 Xu, Y., Jia, Y., Chen, L., Gao, J. & Yang, D. Effect of Streptococcus anginosus on biological response of tongue squamous cell carcinoma cells. BMC Oral Health 21, 141, doi:10.1186/s12903-021-01505-3 (2021).
20 Al Majid, F. et al. Streptococcus anginosus group infections: Management and outcome at a tertiary care hospital. J Infect Public Health 13, 1749-1754, doi:10.1016/j.jiph.2020.07.017 (2020).
21 Hu, T. et al. Spermine oxidase is upregulated and promotes tumor growth in hepatocellular carcinoma. Hepatol Res 48, 967-977, doi:10.1111/hepr.13206 (2018).
22 Chaturvedi, R. et al. Increased Helicobacter pylori-associated gastric cancer risk in the Andean region of Colombia is mediated by spermine oxidase. Oncogene 34, 3429-3440, doi:10.1038/onc.2014.273 (2015).
23 McNamara, K. M., Gobert, A. P. & Wilson, K. T. The role of polyamines in gastric cancer. Oncogene 40, 4399-4412, doi:10.1038/s41388-021-01862-x (2021).
24 Nejman, D. et al. The human tumor microbiome is composed of tumor type-specific intracellular bacteria. Science (New York, N.Y.) 368, 973-980, doi:10.1126/science.aay9189 (2020).
25 Raetz, C. R. & Whitfield, C. Lipopolysaccharide endotoxins. Annu Rev Biochem 71, 635-700, doi:10.1146/annurev.biochem.71.110601.135414 (2002).
26 Dai, H. et al. The Polyamine Oxidase Inhibitor MDL-72,527 Selectively Induces Apoptosis of Transformed Hematopoietic Cells through Lysosomotropic Effects. Cancer Research 59, 4944-4954 (1999).
27 Goodwin, A. C. et al. Polyamine catabolism contributes to enterotoxigenic <em>Bacteroides fragilis</em>-induced colon tumorigenesis. Proceedings of the National Academy of Sciences 108, 15354-15359, doi:10.1073/pnas.1010203108 (2011).
28 Li, J., Meng, Y., Wu, X. & Sun, Y. Polyamines and related signaling pathways in cancer. Cancer Cell Int 20, 539, doi:10.1186/s12935-020-01545-9 (2020).
29 Dai, F. et al. Extracellular polyamines-induced proliferation and migration of cancer cells by ODC, SSAT, and Akt1-mediated pathway. Anti-cancer drugs 28, 457-464 (2017).
30 Ye, Z. et al. ODC1 promotes proliferation and mobility via the AKT/GSK3β/β-catenin pathway and modulation of acidotic microenvironment in human hepatocellular carcinoma. OncoTargets and therapy 12, 4081 (2019).
31 Wang, C. et al. Spermidine/spermine N1-acetyltransferase regulates cell growth and metastasis via AKT/β-catenin signaling pathways in hepatocellular and colorectal carcinoma cells. Oncotarget 8, 1092 (2017).
32 McCullough, F. S., Northrop-Clewes, C. A. & Thurnham, D. I. The effect of vitamin A on epithelial integrity. The Proceedings of the Nutrition Society 58, 289-293, doi:10.1017/s0029665199000403 (1999).
33 Wang, J. L., Swartz-Basile, D. A., Rubin, D. C. & Levin, M. S. Retinoic acid stimulates early cellular proliferation in the adapting remnant rat small intestine after partial resection. The Journal of nutrition 127, 1297-1303, doi:10.1093/jn/127.7.1297 (1997).
34 Amit-Romach, E., Uni, Z., Cheled, S., Berkovich, Z. & Reifen, R. Bacterial population and innate immunity-related genes in rat gastrointestinal tract are altered by vitamin A-deficient diet. The Journal of nutritional biochemistry 20, 70-77, doi:10.1016/j.jnutbio.2008.01.002 (2009).
35 Huang, Z., Liu, Y., Qi, G., Brand, D. & Zheng, S. G. Role of Vitamin A in the Immune System. J Clin Med 7, doi:10.3390/jcm7090258 (2018).
36 Hsu, C. W. et al. Integrated analyses utilizing metabolomics and transcriptomics reveal perturbation of the polyamine pathway in oral cavity squamous cell carcinoma. Anal Chim Acta 1050, 113-122, doi:10.1016/j.aca.2018.10.070 (2019).
37 Madeo, F., Eisenberg, T., Pietrocola, F. & Kroemer, G. Spermidine in health and disease. Science (New York, N.Y.) 359, eaan2788, doi:10.1126/science.aan2788 (2018).