非肿瘤分泌的抗菌肽cathelicidin促进肺癌生长的作用及其机制
Mechanisms of antimicrobial peptide cathelicidin secreted by non-tumorous cells for lung tumor growth
目的 探讨非肿瘤细胞分泌的抗菌肽cathelicidin促进肺癌生长的作用及其机制.方法 Lewis肺癌细胞(LLCl)通过尾静脉注射入cathelicidin敲除小鼠(CRAMP-/-)和对照小鼠(WT)建立小鼠转移性肺癌模型.对小鼠肺重量及表面肿瘤个数进行评价.利用Kaplan-Meier(K-M)生存率曲线分析小鼠生存率.免疫组织化学方法检测小鼠cathelicidin、肿瘤增殖抗原Ki-67和CD68表达;涂片染色计数肺泡灌洗液中各种炎症细胞个数.结果 Cathlicidin在肿瘤组织的炎症免疫细胞中呈高表达状态,而在肿瘤细胞中表达很弱.CRAMP-/-小鼠的肺重量和肿瘤数分别为(0.25±0.04)g和(9.60±2.25)个,均显著低于WT小鼠的(0.65±0.05)g和(23.40±2.68)个(t=6.07、3.95,均P<0.05).K-M生存率分析结果显示,CRAMP-/-小鼠的中位生存时间为49(46 ~51)d,长于Wr小鼠的34(28 ~39) d(x2 =12.00,P<0.05),且组织切片中Ki-67阳性肿瘤细胞为(18.80±2.38)%,明显低于WT小鼠的(35.80±2.96)%(=4.48,P<0.05).肺泡灌洗液炎症细胞计数显示,CRAMP-/-小鼠的总细胞、中性粒细胞、淋巴细胞及巨噬细胞数量分别为(4.72±0.86)×104个、(0.08±0.02)×104个、(0.05±0.02) ×104个和(4.60±0.84)×104个,均低于WT小鼠的(16.18±1.61)×104个、(0.32±0.05)×104个、(0.20±0.05)×104个和(15.66±1.57)×104个(t=6.28、4.39、3.00、6.20,均P<0.05),其中以巨噬细胞数量下降最为明显;免疫组织化学检测结果显示,在肿瘤组织中CRAMP-/-小鼠巨噬细胞的数量为(6.77±3.12)个/高倍视野,明显低于WT小鼠的(15.53±2.28)个/高倍视野(t=3.41,P<0.05).结论 非肿瘤细胞分泌的cathelicidin具有促进小鼠肿瘤细胞增殖及肿瘤生长的作用,募集炎症细胞如巨噬细胞进入肿瘤微环境可能是其主要作用机制.
更多Objective To investigate the effect of antimicrobial peptide cathelicidin secreted by non-tumorous cells in lung tumor growth.Methods CRAMP-/-mice and WT mice were used to establish a lung cancer model via tail vein injection of Lewis lung carcinoma cells (LLC1).Lung was weighted and tumor number on the lung surface was counted.Kaplan-Meier (K-M) survival curve was used to analyze survival rate of mice.Expression of cathelicidin,Ki-67 and CD68 in the tumor tissue was measured by immunohistochemical analysis.BALF cells were stained with Diff Quik and percentages of leukocyte types were determined by light microscopy.Results Cathelicidin was high expression in inflammatory cells of tumor tissue,whereas weak expression in tumor cells.The lung weight and number of tumor in CRAMP-/-mice were (0.25 ± 0.04) g and (9.60 ± 2.25),respectively,which were significantly lower than those of WT mice (0.65 ± 0.05) g and (23.40 ± 2.68).The difference was statistically significant (t =6.07,3.95,all P <0.05).And Kaplan-Meier survival analysis showed median survival time of CRAMP-/-mice was 49 (46-51) d,which was longer than 34 (28-39) d of WT mice (x2 =12.00,P < 0.05).And the positive rate of Ki-67 tumor cells was significant reduced from (35.80 ± 2.96) % in WT mice to (18.80 ± 2.38) % in CRAMP-/-groups (t =4.48,P < 0.05).The total cell number as well as the number of lymphocytes,neutrophils,and macrophages in BALFs of CRAMP-/-mice were (4.72± 0.86) × 104,(0.08-0.02) × 104,(0.05 ± 0.02) × 104 and (4.60 ± 0.84) × 104,respectively,while of WT mice were (16.18±1.61) ×l04,(0.32±0.05) ×l04,(0.20±0.05) ×104 and (15.66±1.57) ×l04.All of them had significant difference(t =6.28,4.39,3.00,6.20,all P <0.05).In addition,the infiltration of macrophages into lung tumors was decreased in CRAMP-/-mice compared to WT mice,from (15.53 ± 2.28)/high power field to (6.77 ±3.12)/high power field (t =3.41,P <0.05).Conclusions Nontumor cells secreted cathelicidin promotes tumor cell proliferation and lung tumor growth.Recruitment of inflammatory cells such as macrophages into the tumor microenvironment may be the main mechanism of action.
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