Functional role of haptoglobin-β chain defined by RM2 in prostate cancer cells

我们已经证明前列腺癌细胞对单克隆抗体RM2的反应性反映了前列腺癌细胞的恶性潜能，前列腺癌细胞中的接触珠蛋白- β链携带对RM2的反应性。在这个项目中，我们旨在阐明由RM2定义的haptoglobin-beta链的功能作用。单克隆抗体RM2对前列腺癌细胞株的影响是：锚定依赖性和非依赖性增殖减少，细胞凋亡增加，运动能力和侵袭能力下降。在5-Aza或PBA处理的前列腺癌细胞系中，RM2定义的触珠蛋白- β链表达减少，信号转导分子表达水平发生变化，导致恶性表型降低。这些结果表明，由RM2定义的接触珠蛋白- β链通过与信号转导分子的相互作用参与了恶性表型。结果表明，许多信号通路如Ras-Akt， Src-FAK等受到RM2定义的haptoglobin-beta链的影响。根据上述结果，我们认为RM2定义的haptoglobin- β链可能影响上层的信号转导。Ras和STAT3表达水平的变化提示EGFR是一个候选分子。用RM2免疫沉淀前列腺癌细胞裂解态后，用抗egfr抗体检测LNCaP、PC3和DU145三种细胞系的条带。此外，用RM2治疗癌细胞可诱导EGFR在胞浆内的运动。这些结果表明，RM2定义的haptoglobin-beta链通过与EGFR相互作用刺激Ras-Akt通路，增加STAT3的表达水平，导致恶性表型的诱导，而RM2定义的haptoglobin-beta链与EGFR的相互作用被单克隆抗体RM2阻断。

We have demonstrated that reactivity of prostate cancer cells to monoclonal antibody RM2 reflected the malignant potential of prostate cancer cells and haptoglobin-beta chain in prostate cancer cells carries the reactivity to RM2. In this project, we aimed to elucidate the functional roles of haptoglobin-beta chain defined by RM2.In the prostate cancer cell lines treated with monoclonal antibody RM2, decrease of anchorage-dependent and -independent proliferation, increased apoptosis and decreased motility and invasive capacity were observed. In the prostate cancer cell lines treated with 5-Aza or PBA, decreased expression of haptoglobin-beta chain defined by RM2 and changes of expression level of signal transduction molecules toward decreased malignant phenotype. These results indicate that haptoglobin-beta chain defined by RM2 is involved in the malignant phenotype by interaction with the signal transduction molecules. It was demonstrated that many signaling pathways such as Ras-Akt, Src-FAK etc. were affected by haptoglobin-beta chain defined by RM2.From the results described above, it was assumed that haptoglobin-beta chain defined by RM2 might affect the upper level of signaling transduction. Changes in expression level of Ras and STAT3 suggest that EGFR is a candidate molecule. After immunoprecipitation of lystates of prostate cancer cells with RM2, the bands were detected by anti-EGFR antibody in all three lines, i.e., LNCaP, PC3 and DU145. Further, treatment of cancer cells with RM2 induced intracytoplasmic movement of EGFR. These results indicate that haptoglobin-beta chain defined by RM2 stimulated Ras-Akt pathway and increased expression level of STAT3 through interaction with EGFR, leading to induction of the malignant phenotype, whereas interaction of haptoglobin-beta chain defined by RM2 with EGFR was blocked by monoclonal antibody RM2.