摘要
合成花生五烯酸(EPA)与透明质酸(HA)耦合物,初步评价其体外抗肝癌活性。通过胱胺将花生五烯酸与透明质酸连接,合成了一种透明质酸-花生五烯酸接枝物(HA-EPA),利用核磁共振仪
不饱和脂肪酸是一类人体生长发育所必须的脂肪酸,根据链长和不饱和程度分为单不饱和脂肪酸和多不饱和脂肪酸两
肝癌是全球第4大肿瘤,与总体肿瘤病死率的下降趋势相反,在过去的几十年中,肝癌的发病率和病死率逐年上
本研究所用花生五烯酸(eicosapentaenoic acid,EPA)是一种广泛存在于海洋动植物中的ω-3不饱和脂肪酸。目前大量药理研究表明EPA对肝癌具有抑制作用,但是其作为一种常见的食用补剂,虽有一定的效果,但相对化疗药物而言还有很大的差距。透明质酸(hyaluronic acid, HA)由于其优秀的亲水性、长循环和安全性被广泛用于脂溶性化合物的药物递
胱胺二盐酸盐(cystamine dihydrochloride,上海萨恩化学技术有限公司);EPA(江苏艾康医药科技有限公司);HA(Mr 8 000,山东福瑞达生物医药有限公司);1-乙基-(3-二甲基氨基丙基)碳酰二亚胺盐酸盐(EDC·HCl)、N-羟基丁二酰亚胺(NHS)(上海阿拉丁生化科技股份有限公司);胎牛血清(fetal bovine serum,FBS,浙江天杭生物科技股份有限公司);多聚甲醛固定液、结晶紫染色液(上海碧云天生物技术有限公司);DMEM培养基、DAPI染色液、AnnexinV Alexa Fluor488/PI凋亡检测试剂盒(北京索莱宝科技有限公司);EdU/Apollo567细胞增殖检测试剂盒、TUNEL细胞凋亡检测试剂盒(广州锐博生物科技有限公司);Transwell小室、Invasion小室(美国Corning公司);其他试剂均为市售分析纯。
ZEN3690激光粒度仪(英国马尔文公司);is50 FT-IR红外分光光度计(美国热电有限公司);Avance Ⅲ 全数字化超导核磁共振谱仪(瑞士布鲁克有限公司);IX53倒置荧光显微镜(日本奥林巴斯股份公司);FACS Verse型流式细胞仪(美国BD生物科技有限公司);酶联免疫检测仪(美国赛默飞世公司)。
精密称取透明质酸20 mmol溶于去离子水中,依次加入EDC·HCl 24 mmol、胱胺二盐酸盐60 mmol,用2 mol/L HCl将溶液pH调至4.75,室温搅拌反应2 h后,加入1 mol/L NaOH将溶液pH调至7,然后终止反应。取反应液于截留分子量为8 000透析袋中,去离子水透析48 h,每4小时换一次透析水。透析完液体冷冻干燥24 h,得乳白色蓬松固体。
将0.5 mmol EPA溶于干燥的二氯甲烷中,先后加入0.6 mmol NHS,1 mmol EDC·HCl,室温搅拌6 h;薄层色谱法监测反应结束后,旋干溶剂得粗产物黄色固体,直接用于下一步反应。
通过MTT法验证了HA-EPA对正常肝细胞LX-2的毒性,并测得了不同浓度与时间下HepG2和Huh-7的细胞存活率;通过EdU、TUNEL、流式凋亡、Transwell与Invasion实验检测250 μmol/L HA、EPA和HA-EPA给药后HepG2的增殖、凋亡、迁移与侵袭相关能力的影响。
HepG2、Huh-7、LX-2细胞用含有1%青霉素链霉素和10% FBS的DMEM培养基培养。待细胞生长稳定后,取处于对数生长期的细胞用于体外细胞实验。
采用MTT法测试EPA与HA-EPA对人肝癌细胞 HepG2、Huh-7及正常肝细胞LX-2的体外活性实验。于96孔板每孔加100 μL含细胞培养液,每孔1 × 1
96孔板每孔2 × 1
铺板给药同细胞增殖实验,给药24 h后弃培养液,固定细胞,加TUNEL检测液,DAPI染色,荧光显微镜成像,计算细胞凋亡率。HepG2细胞以每孔1 × 1
HA和EPA都含有羧基,胱胺两端为氨基。本研究以酰胺反应为合成手段,以EDC和NHS为催化剂,先合成氨基化的透明质酸(HA-amine),再将活化的EPA与之反应,将HA与EPA通过胱胺相连,将EPA成功与HA相连,合成了HA-EPA,合成路线如

Figure 1 Synthesis of hyaluronic acid (HA)- eicosapentaenoic acid (EPA)
HA、EPA和HA-EPA

Figure 2
如

Figure 3 IR spectra of EPA (A), HA (B) and HA-EPA (C)
采用激光粒度仪测定各项指标。测得HA-EPA的平均粒径为(162.5 ± 10.2) nm,PDI为0.188 ± 0.09。经电位分析测试接枝物的Zeta电位为-(4.47 ± 0.31) mV。
如

Figure 4 Cell viability of HepG2 cells (A) and Huh-7 cells (B) treated by EPA or HA-EPA for 24, 48, 72 h ()

Figure 5 Cell viability of LX-2 cells treated by EPA or HA-EPA for 48 h ()
如

Figure 6 EdU proliferation assay analysis of the effect of HA, EPA and HA-EPA on the growth of HepG2 cells ()
A: Typical photos; B: Quantitation of cell proliferation
如

Figure 7 Analysis of apoptosis by TUNEL labeling in HepG2 cells (A-B) and apoptosis cells detected by flow cytometry (C) ()
****P < 0.000 1 vs control group;
进一步采用流式细胞术对细胞凋亡进行检测,HA-EPA组Annexin V阳性细胞最多,这与TUNEL结果一致,表明HA-EPA相较于EPA,具有显著的促进HepG2凋亡作用。3.8 细胞迁移与侵袭实验
实验结果如

Figure 8 Effects of HA-EPA on the migration and invasion of HepG2 cells. The migration (A) and invasion (C) abilities of HepG2 cells were measured by Transwell and invasion assay; and the numbers of the migrated cells (B) and the invasive cells (D) were calculated ()
***P < 0.001,
本研究将HA与EPA通过化学反应接枝在一起得到HA-EPA接枝物,通
接下来,通过MTT实验检测了HA-EPA对肝癌细胞HepG2和Huh-7的毒性实验,HA-EPA与EPA单体相比,HA-EPA能更好地抑制肿瘤增长,且具有时间与剂量依赖性。对正常细胞LX-2的MTT结果表明,HA的负载有效减少了EPA对正常细胞的毒性作用。
本研究通过对肝母细胞瘤细胞HepG2的增殖、凋亡、迁移、侵袭实验,初步探究了HA-EPA对肝癌细胞的体外抑制作用,相较于EPA单体,HA-EPA能显著抑制HepG2的增殖、迁移与侵袭,促进HepG2的凋亡。
综合以上结果,HA-EPA具有出色的生物安全性以及抗肝癌效果,具有较好的应用前景,未来可进一步用于肿瘤治疗与药物递送,HA-EPA的抗肝癌分子机制研究将在后期研究中进行。
References
Abiri B,Vafa M. Dietary omega-3 polyunsaturated fatty acids and treatment of cancer[J]. Adv Obes Weight Manage Control,2018,8(3):198-201. [百度学术]
Echeverría F,Ortiz M,Valenzuela R,et al. Long-chain polyunsaturated fatty acids regulation of PPARs,signaling:relationship to tissue development and aging[J]. Prostaglandins Leukot Essent Fatty Acids,2016,114:28-34. [百度学术]
Valenzuela R,Videla LA. The importance of the long-chain polyunsaturated fatty acid n-6/n-3 ratio in development of non-alcoholic fatty liver associated with obesity[J]. Food Funct,2011,2(11):644-648. [百度学术]
McCarty MF,DiNicolantonio JJ. Minimizing membrane arachidonic acid content as a strategy for controlling cancer:a review[J]. Nutr Cancer,2018,70(6):840-850. [百度学术]
Paixão EMDS,Oliveira ACM,Pizato N,et al. The effects of EPA and DHA enriched fish oil on nutritional and immunological markers of treatment naïve breast cancer patients:a randomized double-blind controlled trial[J]. Nutr J,2017,16(1):71. [百度学术]
Fabian CJ,Kimler BF,Hursting SD. Omega-3 fatty acids for breast cancer prevention and survivorship[J]. Breast Cancer Res,2015,17:62. [百度学术]
Biondo PD,Brindley DN,Sawyer MB,et al. The potential for treatment with dietary long-chain polyunsaturated n-3 fatty acids during chemotherapy[J]. J Nutr Biochem,2008,19(12):787-796. [百度学术]
Calviello G,Serini S,Piccioni E,et al. Antineoplastic effects of n-3 polyunsaturated fatty acids in combination with drugs and radiotherapy:preventive and therapeutic strategies[J]. Nutr Cancer,2009,61(3):287-301. [百度学术]
Bougnoux P,Hajjaji N,Maheo K,et al. Fatty acids and breast cancer:sensitization to treatments and prevention of metastatic re-growth[J]. Prog Lipid Res,2010,49(1):76-86. [百度学术]
Berquin IM,Min YN,Wu RP,et al. Modulation of prostate cancer genetic risk by omega-3 and omega-6 fatty acids[J]. J Clin Invest,2007,117(7):1866-1875. [百度学术]
Tapia G,Valenzuela R,Espinosa A,et al. N-3 long-chain PUFA supplementation prevents high fat diet induced mouse liver steatosis and inflammation in relation to PPAR-α upregulation and NF-κB DNA binding abrogation[J]. Mol Nutr Food Res,2014,58(6):1333-1341. [百度学术]
Allam-Ndoul B,Guénard F,Barbier O,et al. Effect of n-3 fatty acids on the expression of inflammatory genes in THP-1 macrophages[J]. Lipids Health Dis,2016,15:69. [百度学术]
Liu YY,Tian YY,Guo Y,et al. DHA-enriched phosphatidylcholine suppressed angiogenesis by activating PPARγ and modulating the VEGFR2/Ras/ERK pathway in human umbilical vein endothelial cells[J]. Food Sci Biotechnol,2021,30(12):1543-1553. [百度学术]
Xue ML,Wang Q,Zhao JL,et al. Docosahexaenoic acid inhibited the Wnt/β-catenin pathway and suppressed breast cancer cells in vitro and in vivo[J]. J Nutr Biochem,2014,25(2):104-110. [百度学术]
Albert BB,Cameron-Smith D,Hofman PL,et al. Oxidation of marine omega-3 supplements and human health[J]. Biomed Res Int,2013,2013:464921. [百度学术]
Spencer L,Mann C,Metcalfe M,et al. The effect of omega-3 FAs on tumour angiogenesis and their therapeutic potential[J]. Eur J Cancer,2009,45(12):2077-2086. [百度学术]
Rehman K,Mohd Amin MC,Yuen NP,et al. Immunomodulatory effectiveness of fish oil and omega-3 fatty acids in human non-melanoma skin carcinoma cells[J]. J Oleo Sci,2016,65(3):217-224. [百度学术]
Rehman K,Zulfakar MH. Novel fish oil-based bigel system for controlled drug delivery and its influence on immunomodulatory activity of imiquimod against skin cancer[J]. Pharm Res,2017,34(1):36-48. [百度学术]
Chen W,Sun K,Zheng R,et al. Cancer incidence and mortality in China,2014[J]. Chin J Cancer Res,2018,30(1):1-12. [百度学术]
Soleymani J,Hasanzadeh M,Shadjou N,et al. The role of nanomaterials on the cancer cells sensing based on folate receptor:Analytical approach[J]. Trac Trends Anal Chem,2020,125:115834. [百度学术]
Li YJ,Dong M,Kong FM,et al. Folate-decorated anticancer drug and magnetic nanoparticles encapsulated polymeric carrier for liver cancer therapeutics[J]. Int J Pharm,2015,489(1/2):83-90. [百度学术]
Shen SY,Xu X,Lin SQ,et al. A nanotherapeutic strategy to overcome chemotherapeutic resistance of cancer stem-like cells[J]. Nat Nanotechnol,2021,16(1):104-113. [百度学术]
Pang X,Lu Z,Du HL,et al. Hyaluronic acid-quercetin conjugate micelles:synthesis,characterization,in vitro and in vivo evaluation[J]. Colloids Surf B Biointerfaces,2014,123:778-786. [百度学术]
Lai HL,Ding X,Ye JX,et al. pH-responsive hyaluronic acid-based nanoparticles for targeted curcumin delivery and enhanced cancer therapy[J]. Colloids Surf B Biointerfaces,2021,198:111455. [百度学术]