Department of Biochemistry and Molecular Biology, Faculty of Veterinary Medicine, Wroclaw University of Environmental and Life Sciences, C.K. Norwida 31, 50-375, Wroclaw, Poland.
Division of Histology and Embryology, Department of Human Morphology and Embryology, Wroclaw Medical University, T. Chalubinskiego 6a, 50-368, Wroclaw, Poland.
Sci Rep. 2023 Apr 21;13(1):6574. doi: 10.1038/s41598-023-33707-w.
We have previously shown that high expression of prolactin-induced protein (PIP) correlates with the response of breast cancer (BC) patients to standard adjuvant chemotherapy (doxorubicin and cyclophosphamide), which suggests that the absence of this glycoprotein is associated with resistance of tumor cells to chemotherapy. Therefore, in the present study, we analyzed the impact of PIP expression on resistance of BC cells to anti-cancer drugs and its biological role in BC progression. Expression of PIP and apoptotic genes in BC cell lines was analyzed using real-time PCR and Western blotting. PIP was detected in BC tissue specimens using immunohistochemistry. The tumorigenicity of cancer cells was analyzed by the in vivo tumor growth assay. Apoptotic cells were detected based on caspase-3 activation, Annexin V binding and TUNEL assay. The interaction of PIP with BC cells was analyzed using flow cytometry. Using two cellular models of BC (i.e. T47D cells with the knockdown of the PIP gene and MDA-MB-231 cells overexpressing PIP), we found that high expression of PIP resulted in (1) increased sensitivity of BC cells to apoptosis induced by doxorubicin (DOX), 4-hydroperoxycyclophosphamide (4-HC), and paclitaxel (PAX), and (2) improved efficacy of anti-cancer therapy with DOX in the xenograft mice model. Accordingly, a clinical study revealed that BC patients with higher PIP expression were characterized by longer 5-year overall survival and disease-free survival. Subsequent studies showed that PIP up-regulated the expression of the following pro-apoptotic genes: CRADD, DAPK1, FASLG, CD40 and BNIP2. This pro-apoptotic activity is mediated by secreted PIP and most probably involves the specific surface receptor. This study demonstrates that a high expression level of PIP sensitizes BC cells to anti-cancer drugs. Increased sensitivity to chemotherapy is the result of pro-apoptotic activity of PIP, which is evidenced by up-regulation of specific pro-apoptotic genes. As high expression of PIP significantly correlated with a better response of patients to anti-cancer drugs, this glycoprotein can be a marker for the prognostic evaluation of adjuvant chemotherapy.
我们之前的研究表明，催乳素诱导蛋白（PIP）的高表达与乳腺癌（BC）患者对标准辅助化疗（阿霉素和环磷酰胺）的反应相关，这表明这种糖蛋白的缺失与肿瘤细胞对化疗的耐药性有关。因此，在本研究中，我们分析了 PIP 表达对 BC 细胞对抗癌药物耐药性的影响及其在 BC 进展中的生物学作用。使用实时 PCR 和 Western blot 分析 BC 细胞系中 PIP 和凋亡基因的表达。使用免疫组织化学检测 BC 组织标本中的 PIP。通过体内肿瘤生长试验分析癌细胞的致瘤性。根据 caspase-3 激活、Annexin V 结合和 TUNEL 试验检测凋亡细胞。使用流式细胞术分析 PIP 与 BC 细胞的相互作用。使用两种 BC 细胞模型（即敲低 PIP 基因的 T47D 细胞和过表达 PIP 的 MDA-MB-231 细胞），我们发现 PIP 的高表达导致（1）BC 细胞对阿霉素（DOX）、4-羟基环磷酰胺（4-HC）和紫杉醇（PAX）诱导的凋亡更加敏感，（2）在异种移植小鼠模型中提高了 DOX 抗癌治疗的疗效。因此，一项临床研究表明，PIP 表达较高的 BC 患者具有更长的 5 年总生存率和无病生存率。随后的研究表明，PIP 上调了以下促凋亡基因的表达：CRADD、DAPK1、FASLG、CD40 和 BNIP2。这种促凋亡活性是由分泌的 PIP 介导的，很可能涉及特定的表面受体。本研究表明，PIP 的高表达水平使 BC 细胞对抗癌药物敏感。对化疗的敏感性增加是 PIP 促凋亡活性的结果，这表现在特定促凋亡基因的上调。由于 PIP 的高表达与患者对抗癌药物的反应显著相关，因此这种糖蛋白可以作为辅助化疗预后评估的标志物。
