生长抑素Ⅱ型受体在Dukes D期大肠癌及肝转移灶中的表达及其与血管内皮生长因子的关系

Expression of somatostatin receptor subtype 2 in Dukes D sporadic colorectal cancer and corresponding liver metastasis and its relationship with VEGF

目的观察生长抑素Ⅱ型受体在大肠癌伴肝转移患者病变组织中的表达，同时比较血管内皮生长因子（VEGF）的表达状况。方法（1）采用实时逆转录-聚合酶链反应（RT-PCR）及免疫组织化学两种方法测定32例大肠癌患者原发灶及相应肝转移灶中sst2的表达，所测数据采用方差分析的方法与患者的年龄、性别、肿瘤位置、组织学分型、生长方式、术前CEA水平比较；（2）采用免疫组织化学法检测了病灶中VEGF的表达，并与上述sst2的测定数据进行直线回归分析。结果（1）sst2在所有检测的原发肿瘤组织中均有表达，并不与肿瘤的位置、生长方式、组织学类型相关（P〉0．05）；（2）肝转移灶中表达的sst2量与原发灶比较，差异无统计学意义（P〉0．05）；（3）对伴有CEA升高（〉5μg/L）的患者，其肝转移灶及原发灶均比术前CEA较低（〈5μg/L）患者表现出sst2表达下调（原发灶P〈0．01，肝转移灶P〈0．01）；（4）肿瘤原发灶及肝转移灶中，sst2均与VEGF呈现明显负相关（r=0．425，P〈0．05）。结论（1）sst2在伴有肝转移的大肠癌患者原发灶及肝转移灶中均有表达，差异无统计学意义；（2）sst2表达与患者术前CEA水平有关；（3）生长抑素通过抑制VEGF发挥抗肿瘤新生血管形成的作用不仅在大肠癌原发灶中起作用，而且可能对肝转移灶同样有效。

Objective By studying the expression of somatostatin receptor subtype 2 （sst2） mRNA in colorectal cancer and its corresponding liver metastasis and comparing the expression of VEGF, to explore the possibility of somatostatin and its analogues in the treatment of colorectal cancer and the possible mechanism of antitomor effect of the somatostatin. Methods （ 1 ） Both the RT-PCR and immunohistochemistry were used to detect the expression of sst2 in 32 patients＇ primary tumor and its corresponding liver metastasis ; （2） The expression of VEGF was detected by using immunohistochemistry, and compared with that of the ssts by means of linear correlation and regression. Results （ 1 ） sst2 was expressed in all primary tumors and corresponding liver metastasis, and its expression was not related with tumor＇ s location,growth pattern, histologic type （P 〉 0.05 ） ;（2） There was no significant difference in the expression between liver metastasis and primary tumors （ P 〉 0.05 ） ; （ 3 ） In the patients with elevated CEA preoperatively （ 〉 5 μg/L） ,the expression of sst2 in primary tumor and lvier metastasis （ bothP 〈 0.01 ） ; （4） The expression of sst2 was negatively correlated with that of VEGF in both the primary and metastasis tumors （ r = 0. 425,P 〈 0.05 ）. Conclusion （ 1 ） sst2 was expressed in both primary colorectal cancer and its corresponding metastasis with the difference being not significant between them; （2） With regard to those who have elevated CEA values,the expression of sst2 was lower in both primary and its metastasis tumors; （3） The indirect antitumor effect of somatostatin by means of inhibiting VEGF not only works on the primary tumor but also on the liver metastasis.