骨唾液蛋白(BSP)高稳定表达对乳腺癌骨转移的促进作用

Studies on the effects of BSP over-expression in facilitating the metastasis of breast cancer cells to bone

目的了解乳腺癌细胞中骨唾液蛋白(BSP)高稳定表达对其骨转移的影响,为乳腺癌骨转移的预防和治疗寻找新的药物靶点。方法通过鸡胚尿囊绒膜实验和骨条黏附实验确定BSP的高稳定表达对乳腺癌细胞血管侵袭能力及骨条黏附能力的影响。将乳腺癌细胞种植于鸡胚尿囊膜的上部空腔,经过孵育收集下囊腔血管组织,PCR检测人特异的Alu基因,以了解乳腺癌细胞的血管侵袭能力;将乳腺癌细胞与经胶原酶和胰蛋白酶消化的骨条共同孵育,胰酶消化收集乳腺癌细胞,通过染色测定OD_(488)值来确定乳腺癌细胞对骨条的黏附。结果空白对照组和未经转染的乳腺癌细胞组各5个鸡胚中均没有扩增出人的Alu基因,BSP高稳定表达的乳腺癌细胞MDA-MB-231BO(pI)和MDA-MB-231BO(piE))各5个鸡胚中分别有4个和3个扩增出人Alu基因;乳腺癌细胞MDA-MB-231BO(pI)和MDA-MB-231BO(pID)的骨条黏附实验测得的488nm处的吸光度值分别为0.580±0.046和0.490±0.039,明显高于未经转染的乳腺癌细胞组(0.260±0.021,P<0.05)和空白对照组(0.034±0.003,P<0.01)。结论BSP的高稳定表达增加了乳腺癌细胞的血管侵袭能力,提高了乳腺癌细胞的骨条黏附能力,可能对乳腺癌的骨转移有一定促进作用。

Objective The study was aiming at elucidating the rale of BSP over-expression in enhancing osseous metastasis of breast cancer cells, in order to search for new drug targets for prevention and treatment of such metastasis. Methods Chicken embryo allantois membrane （CAM） was used in the experiment. Breast cancer cells were inoculated on the superior surface of CAM sac, then the vascular tissues were collected in lower sac after incubation. The human specific Alu gene was amplified by PCR with genomic DNA extracted as template. Breast cancer cells were incubated with bone, which had becn treated with collagenase and trypsinase, and then OD488 of breast cancer was assessed to evaluate the adhesive affinity of breast cancer cells to bone. Results The findings of CAM assay and PCR amplification using human Alu primers and genomic DNA showed that Alu gene was amplified from 4 of 5 in MDA-MB-231BO （pI） group and 3 of 5 in MDA-MB-231BO （pID） group, but not amplified in control group. In bone adhesion assay, the OD488 of digested bone after MDA-MB-231BO （pI） and MDA-MB-231BO （pID） adhering to bone were 0. 58±0. 046 and 0.49±0. 039, respectively, which were larger than that of MDA-MB-231BO （0. 26±0. 021, P〈0. 05）, and also showed significant difference with that of the blank control （0. 034±0. 003, P〈0. 01）. Conclusion Over-expression of BSP might enhance the penetrating ability of tumor cells through endothelial cells and basement membrane into blood vessels, as well as the affinity of breast cancer cells to adhere to bone, implying that over-expression of BSP might facilitate the metastasis of breast cancer cells to bone.