Department of Biological Sciences, Clemson University, Clemson, SC 29634, USA.
Breast Cancer Res Treat. 2012 Jul;134(1):157-69. doi: 10.1007/s10549-012-1954-3. Epub 2012 Jan 22.
Prolactin (PRL) promotes the proliferation and survival of breast cancer cells in part via the transactivation of human epidermal growth factor receptor 2 (HER2), also known as Neu in rodents. A PRL receptor (PRLR) antagonist, G129R, has been developed, which indirectly inhibits the tyrosine phosphorylation of HER2 (p-HER2) in human breast cancer cell lines. In this study, we investigate the effects of cancer-associated fibroblasts (CAFs) upon this molecular cross-talk using tumor cells and CAFs derived from spontaneous mammary tumors of female MMTV-neu transgenic mice. Tumors were resected and cultured as small tumor chunks (3 mm3) or were cultured in monolayer. G129R reduced tyrosine phosphorylation of Neu (p-Neu) in a dose-dependent manner (IC5010 μg/ml) in tumor chunks, but had no effect on primary tumor epithelial cells grown in monolayer. Direct co-culture of mouse or human tumor epithelial cell lines with CAFs restored the epithelial cells' response to G129R, similar to that observed in mouse tumor chunks. The addition of PRL, as expected, induced p-Neu in both the tumor chunk and co-culture models. The inhibitory effect of G129R was absent when CAFs were physically separated from mouse tumor epithelial cells using a transwell system, or when CAFs were replaced with normal fibroblasts in direct co-culture with human or mouse tumor epithelial cells. In vivo, G129R reduced p-Neu levels in primary mammary tumors of mice in a time- and dose-dependent manner. In conclusion, CAFs play a critical role in bridging the cross-talk between PRL and HER2/Neu in both mouse and human models of breast cancer. The inhibitory effects of G129R on p-Neu and on tumor growth are dependent upon interactions of tumor epithelial cells with CAFs.
催乳素（PRL）通过人表皮生长因子受体 2（HER2）的转激活，部分促进乳腺癌细胞的增殖和存活，HER2 在啮齿动物中也称为 Neu。已经开发出一种 PRL 受体（PRLR）拮抗剂 G129R，它间接抑制人乳腺癌细胞系中 HER2 的酪氨酸磷酸化（p-HER2）。在这项研究中，我们使用源自雌性 MMTV-neu 转基因小鼠自发乳腺肿瘤的肿瘤细胞和 CAF 研究了 CAF 对这种分子串扰的影响。肿瘤被切除并培养为小肿瘤块（3mm3）或单层培养。G129R 以剂量依赖性方式降低肿瘤块中 Neu 的酪氨酸磷酸化（p-Neu）（IC5010μg/ml），但对单层培养的原发性肿瘤上皮细胞没有影响。将小鼠或人肿瘤上皮细胞系与 CAF 直接共培养恢复了上皮细胞对 G129R 的反应，类似于在小鼠肿瘤块中观察到的反应。如预期的那样，PRL 的添加诱导了肿瘤块和共培养模型中的 p-Neu。当使用 Transwell 系统将 CAF 从小鼠肿瘤上皮细胞物理分离，或在直接共培养中用人或小鼠肿瘤上皮细胞替换正常成纤维细胞时，G129R 的抑制作用不存在。在体内，G129R 以时间和剂量依赖性方式降低小鼠原发性乳腺肿瘤中的 p-Neu 水平。总之，CAF 在人乳腺癌模型和小鼠模型中均在 PRL 和 HER2/Neu 之间的串扰中发挥关键作用。G129R 对 p-Neu 和肿瘤生长的抑制作用取决于肿瘤上皮细胞与 CAF 的相互作用。
