Salim Elsayed I, Abou-Shafey Ahlam E, Masoud Ahmed A, Elgendy Salwa A
Department of Zoology, Faculty of Science, Tanta University, Tanta, Egypt.
Asian Pac J Cancer Prev. 2011;12(9):2385-92.
The possible chemopreventive effects of natural Egyptian flaxseed oil on preneoplasia and cancer formation were investigated in a rat medium-term colon carcinogenesis bioassay. Male Wistar rats were divided into 6 groups. Groups 1, 3 and 5 were initiated by 1,2-dimethylhydrazine (DMH) 20 mg/kg body weight s.c. 8 times, twice a week to initiate colon carcinogenesis. Groups 1 and 3 received 20% or 5% flaxseed oil respectively in diet in post initiation stage until the end. Groups 2 and 4 served as a flaxseed dose corresponding controls without carcinogen initiation, while rats in group 6 served as negative controls. Distribution and total numbers of aberrant crypt foci (ACF), putative preneoplastic lesions, particularly those with ≥4 aberrant crypts (ACs), and the numbers and sizes of colon tumors (adenoma and carcinoma) were significantly decreased by both treatment doses of flaxseeds as compared to group 5. Histochemical investigation revealed that the numbers of mucus-secreting cells in the colonic mucosa were reduced gradually during progression of colon carcinogenesis. Intriguingly, flaxseed oil caused the numbers and integrity of the mucus-secreting cells to retain close to normal levels and in a dose dependent manner. Moreover, the hematological parameters were almost constant between the groups particularly at the dose of 5% as compared to groups 5 and 6. PCNA-labeled indexes (PCNA-LI) in the DMH-initiated colonic mucosa were found to be decreased by both doses of flaxseeds administration. In conclusion, the present study showed that the post initiation dietary administration of flaxseeds oil suppressed DMH-induced colon carcinogenesis in rats without significant side effects. The mechanism is likely to be through its inhibitory effects on early cellular proliferation and modulation of mucin secretion properties in the initiated colonic mucosa.
在一项大鼠中期结肠癌发生生物测定中，研究了天然埃及亚麻籽油对癌前病变和癌症形成的潜在化学预防作用。雄性Wistar大鼠被分为6组。第1、3和5组通过皮下注射1,2 - 二甲基肼（DMH）20 mg/kg体重，每周两次，共8次来启动结肠癌发生。在启动后的阶段，第1和3组分别在饮食中摄入20%或5%的亚麻籽油直至实验结束。第2和4组作为未用致癌物启动的亚麻籽剂量对应对照组，而第6组大鼠作为阴性对照组。与第5组相比，两种剂量的亚麻籽处理均显著降低了异常隐窝灶（ACF）的分布和总数，ACF是假定的癌前病变，特别是那些具有≥4个异常隐窝（AC）的病变，以及结肠肿瘤（腺瘤和癌）的数量和大小。组织化学研究表明，在结肠癌发生过程中，结肠黏膜中黏液分泌细胞的数量逐渐减少。有趣的是，亚麻籽油使黏液分泌细胞的数量和完整性以剂量依赖的方式保持接近正常水平。此外，与第5和6组相比，各实验组之间的血液学参数几乎恒定，特别是在5%剂量组。发现两种剂量的亚麻籽给药均降低了DMH启动的结肠黏膜中的增殖细胞核抗原标记指数（PCNA - LI）。总之，本研究表明，启动后饮食中给予亚麻籽油可抑制DMH诱导的大鼠结肠癌发生，且无明显副作用。其机制可能是通过对早期细胞增殖的抑制作用以及对启动的结肠黏膜中黏蛋白分泌特性的调节。
