张晓飞　李亚斌　王塬

721001　陕西省宝鸡市中医医院外二科



·论著·

结直肠癌组织及血红细胞中多不饱和脂肪酸的分布情况及诊断价值

张晓飞李亚斌王塬

721001陕西省宝鸡市中医医院外二科

【摘要】目的本研究对结直肠癌患者的组织及血液中的多不饱和脂肪酸(PUFA)的含量进行分析，评价PUFA含量在结直肠癌诊治中的价值。方法选取2010年3月至2015年3月就诊并诊断为结直肠癌的患者共76例，取血保留并于手术中收集其肿瘤组织以及癌周正常组织的标本。分别检测血红细胞液中以及肿瘤组织中的PUFA，并计算各脂肪酸成分与总脂酸比值以及ω-6/ω-3 PUFA总比值进行比较分析。结果血红细胞中LA高于ALA(P<0.01)，AA高于DHA(P<0.01)，总ω-3 PUFA低于ω-6 PUFA(P<0.01)；肿瘤组织中LA高于ALA，AA高于DHA且总ω-3 PUFA低于ω-6 PUFA(P<0.01)；肿瘤组织中LA和总ω-6 PUFA的含量均低于癌周正常组织(P<0.01)，而DPA、DHA和总ω-3 PUFA的含量与癌周正常组织比较显著增高(P<0.01)；VEGF阳性患者的LA和ω-6 PUFA高于阴性患者(P<0.01)，而P53和Ki-67表达中LA以及总PUFA差异均无统计学意义(P>0.05)。结论多不饱和脂肪酸在体内的分布与肿瘤的发生密切相关，且可以作为诊断指标具有一定肿瘤诊断价值。

【关键词】结直肠癌；多不饱和脂肪酸；诊断价值

结直肠癌是最常见的恶性肿瘤，发病年龄趋近于老年化，在我国以年均4.2%的速度增长。其发病与生活方式、遗传、大肠腺癌等密切相关，最可控的因素为高脂肪低纤维素饮食的生活方式[1,2]。2000年营养基因组学的提出，引起了科学家对关于机体营养状态与肿瘤关系的关注，此学说认为可以通过饮食结构的改变调整基因表达从而调控肿瘤特质，而多不饱和脂肪酸(PUFA)作为机体内可发挥促进生长发育、抗心脑血管病以及抗炎、抗癌等重要功能的物质，成为国内外学者的重点突破对象[3,4]。结肠癌与饮食习惯的相关性，为研究PUFA提供了有利条件，而目前内外研究仅聚焦于胃癌、肝癌等细胞水平的实验，对动物组织分析的研究缺乏清晰认识[5-8]。本研究即通过收集结直肠癌患者的组织及备注对其中PUFA的含量进行分析讨论，评价PUFA含量在结直肠癌诊治中的价值。

1资料与方法

1.1一般资料选取2010年3月至2015年3月我科就诊并诊断为结直肠癌的患者76例，取血保留并于手术中收集其肿瘤组织以及非癌组织的标本。所有患者经术后病理检查结果证实均为结直肠癌，TNM分期为Ⅰ期10例，Ⅱ期21例，Ⅲ期45例。排除严重心肺疾病以及具有结直肠癌家族史患者[9]。

1.2方法进行血液和肿瘤组织中的脂肪酸提取，将血液标本按1∶10加入双蒸水溶血并离心制成红细胞液，取50 mg结直肠癌标本置于研钵中，加入液氮研磨成粉状静置，收集组织匀浆液进行定量。将两种细胞液加入1 ml正乙烷和三氟化硼后充分振荡。将混合物加热至沸腾持续1 h，冷却后加入1 ml去离子水提取上层甲基酯。离心后用200 μl正乙烷干燥样品并密封利用气相层析分析仪(GC-1010，日本岛津SHIMADZU公司)分析样品并生成检测报告。

1.3效果评价分别检测血红细胞液中以及肿瘤组织中的PUFA，分别为：(1)ω-3 PUFA：亚麻酸(ALA)、二十碳五烯酸(EPA)、二十二碳五烯酸(DPA)、二十二碳六烯酸(DHA)；(2)ω-6 PUFA：亚油酸(LA)、花生四烯酸(AA)、花生三烯酸(DGLA)、十八碳三烯酸(GLA)。并计算各脂肪酸成分与总脂酸比值以及ω-6/ω-3 PUFA总比值进行比较分析。

2结果

2.1结直肠癌患者血红细胞及肿瘤组织中PUFA的分布对血红细胞中各类PUFA的含量进行分析，其LA高于ALA(P<0.01)，AA高于DHA(P<0.01)，总ω-3 PUFA低于ω-6 PUFA(P<0.01)；而肿瘤组织中同样LA高于ALA，AA高于DHA且总ω-3 PUFA低于ω-6 PUFA(P<0.01)。见表1。

表1　结直肠癌患者血红细胞及肿瘤组织中PUFA的分布情况　±s

注：与ALA比较，*P<0.05；与DHA比较，#P<0.05；与ω-3 PUFA比较，△P<0.05

2.2结直肠癌患者正常组织与肿瘤组织中PUFA的分布情况对癌周正常组织与肿瘤组织中PUFA的含量进行分析，肿瘤组织中LA和总ω-6 PUFA的含量均低于癌周正常组织(P<0.01)，而DPA、DHA和总ω-3 PUFA的含量与癌周正常组织比较显著增高(P<0.01)，差异有统计学意义。见表2。

表2　结直肠癌患者癌周正常组织及肿瘤组织中PUFA的分布比较　±s

2.3PUFA含量与结直肠癌患者相关肿瘤因子表达的相关性分析VEGF阳性患者的LA和ω-6 PUFA高于阴性患者(P<0.01)，而P53和Ki-67表达中LA以及总PUFA差异均无统计学意义(P>0.05)。见表3。

表3　PUFA含量与结肠癌患者相关肿瘤因子表达的相关性分析　±s

3讨论

多不饱和脂肪酸对人体生理作用的意义重大，ω-3和ω-6系列PUFA在体内有着各自的代谢途径，但所需酶类为同一酶系，因此在功能上相互协调制约，存在竞争性抑制作用[10,11]。ω-3能够抑制体内炎性因子产生和肿瘤血管新生，而ω-6则可促进肿瘤生长。因此两者的动态平衡对结直肠癌患者的肿瘤发生与发展具有重要意义，本研究即采集结直肠癌患者的血液和肿瘤组织标本进行分析，证明多不饱和脂肪酸在体内的分布与肿瘤的发生密切相关，且可以作为诊断指标具有一定肿瘤诊断价值[12]。

ω-6 PUFA中的LA通过脱饱和酶的作用产生下游产物DGLA和AA，而两种组织液中的LA等升高说明此代谢途径得以加强，抑制了ω-3PUFA的发生[13,14]。AA及其代谢产物PGE2、TXA2和LTB4等可激活炎性因子释放，进而细胞恶变以及肿瘤生长和转移。在本实验中，血红细胞和肿瘤细胞的LA均高于ALA，AA高于DHA，总ω-3 PUFA低于ω-6 PUFA。这说明无论在肿瘤内还是患者血液中，ω-6途径均处于优势地位，这一结论符合现代饮食不均衡造成两种PUFA失衡的观点[15,16]。而将肿瘤组织与癌周正常组织进行比较，发现肿瘤组织中LA和总ω-6 PUFA的含量均低于癌周正常组织，而DPA、DHA和总ω-3 PUFA的含量与正常组织比较显著增高，此结果说明在肿瘤组织中ω-6 PUFA大量分解成AA进而激活磷脂酶C以及蛋白激酶C等，而癌周正常组织为此代谢途径提供有力的微环境，更加有利于结直肠癌患者以ω-6 PUFA为主的脂肪代谢顺利进行，同样ω-3代谢途径被严重抑制，炎性因子被释放促进肿瘤血管新生诱发转移。

PUFA不仅可以通过前列腺素等介导不同癌症的病理发展过程，还可以干扰细胞信号通路以及基因表达过程，因此与体内相关肿瘤发生因子的表达具有重要关系[17, 18]。血管内皮生长因子(VEGF)参与肿瘤的浸润、转移，是结直肠癌新生血管的最重要因子之一[19-21]。在本实验中我们将VEGF的阳性和阴性肿瘤患者的PUFA分别进行分析，发现其与LA的含量以及ω-6 PUFA的含量具有重要关系，在VEGF阳性患者中两者的比例明显升高，说明PUFA在某种程度上可以提示结直肠癌的发生，证明了其在机体中促肿瘤与抗肿瘤的平衡在代谢中的作用。而在Ki-67和P53阳性的患者中各种表达程度的肿瘤标志因子与多不饱和脂肪酸含量无明显差异。

综上所述，PUFA在结直肠癌的发生发展中起重要的调节作用，ω-3和ω-6两族PUFA的失衡会影响脂肪酸的代谢为炎性反应以及肿瘤生长因子的释放提供有利条件。因此应注重结直肠癌患者的饮食方式和营养摄入，减少饮食中油脂比较，增加蔬菜水果以及纤维素的吸收，并尽可能的多食深海鱼类，补充EPA和DHA可对结直肠癌的预防和治疗起到重要作用。

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The distribution and diagnostic value of polyunsaturated fatty acids in red blood cells and colorectal cancer tissues

ZHANGXiaofei,LIYabin,WANGYuan.

TheSecondDepartmentofSurgery,ChineseMedicineHospitalofBaojiCity,Shanxi,Baoji721001,China

【Abstract】ObjectiveTo analyze the distribution of polyunsaturated fatty acids (PUFA) in red blood cells and colorectal cancer tissues in order to evaluate the diagnostic value of PUFA in colorectal cancer .MethodsA total of 76 patients who were diagnosed as colorectal cancer in Department of General Surgery of Baoji TCM Hospital from March 2013 to March 2015 were enrolled in the study. The patients’blood specimens, cancer tissues and normal tissues around the cancer were collected. The contents of PUFA in red blood cells and tumor tissues were detected, and the ratio of fatty acid compositions/total fatty acid as well as the total ratio of ω-6/ω-3 PUFA were calculated and analyzed.ResultsThe levels of LA in red cells were significantly higher than those of ALA (P<0.01), the contents of AA were obviously higher than those of DHA (P<0.01), and total ω-3 PUFA levels were significantly lower than those of ω-6 PUFA (P<0.01). The contents of LA in tumor tissues were significantly higher than those of ALA,furthermore, the levels of AA were obviously higher than those of DHA,however, the levels of ω-3 PUFA were significantly lower than those of ω-6 PUFA (P<0.01). Moreover the contents of LA and ω-6 in tumor tissues were significantly lower than those in normal tissues around cancer (P<0.01), however, the contents of DPA, DHA and total ω-3 PUFA were significantly increased,as compared with those in normal tissues around cancer (P<0.01) The levels of LA and ω-6 PUFA in VEGF positive patients were significantly higher than those of patients with negative VEGF (P<0.01),but there were no significant differences in the expression levels of P53 and Ki-67 between LA and total PUFA (P>0.05).Conclusion The distribution of polyunsaturated fatty acids in the body is closely related to the pathogenesis of cancer,thus,which plays an important role in the diagnosis of cancer.

【Key words】colorectal cancer; polyunsaturated fatty acids; diagnostic value

(收稿日期：2015-06-06)

【中图分类号】R 735.37

【文献标识码】A

【文章编号】1002-7386(2016)10-1478-03

doi:10.3969/j.issn.1002-7386.2016.10.010