Nelson Erik R, Li Shenduo, Kennedy Margaret, Payne Sturgis, Kilibarda Kelly, Groth Jeffrey, Bowie Michelle, Parilla-Castellar Edgardo, de Ridder Gustaaf, Marcom Paul Kelly, Lyes Matthew, Peterson Bercedis L, Cook Michael, Pizzo Salvatore V, McDonnell Donald P, Bachelder Robin E
Department of Molecular and Integrative Physiology, University of Illinois at Urbana Champaign, Urbana and University of Illinois Cancer Center, University of Illinois at Chicago, Chicago, IL, USA.
Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, NC, USA.
Oncotarget. 2016 Dec 20;7(51):84030-84042. doi: 10.18632/oncotarget.12767.
Although most triple-negative breast cancer (TNBC) patients initially respond to chemotherapy, residual tumor cells frequently persist and drive recurrent tumor growth. Previous studies from our laboratory and others' indicate that TNBC is heterogeneous, being composed of chemo-sensitive and chemo-resistant tumor cell subpopulations. In the current work, we studied the invasive behaviors of chemo-resistant TNBC, and sought to identify markers of invasion in chemo-residual TNBC.
The invasive behavior of TNBC tumor cells surviving short-term chemotherapy treatment in vitro was studied using transwell invasion assays and an experimental metastasis model. mRNA expression levels of neural cadherin (N-cadherin), an adhesion molecule that promotes invasion, was assessed by PCR. Expression of N-cadherin and its precursor form (pro-N-cadherin) was assessed by immunoblotting and flow cytometry. Pro-N-cadherin immunohistochemistry was performed on tumors obtained from patients pre- and post- neoadjuvant chemotherapy treatment.
TNBC cells surviving short-term chemotherapy treatment exhibited increased invasive behavior and capacity to colonize metastatic sites compared to untreated tumor cells. The invasive behavior of chemo-resistant cells was associated with their increased cell surface expression of precursor N-cadherin (pro-N-cadherin). An antibody specific for the precursor domain of N-cadherin inhibited invasion of chemo-resistant TNBC cells. To begin to validate our findings in humans, we showed that the percent cell surface pro-N-cadherin (+) tumor cells increased in patients post- chemotherapy treatment.
TNBC cells surviving short-term chemotherapy treatment are more invasive than bulk tumor cells. Cell surface pro-N-cadherin expression is associated with the invasive and chemo-resistant behaviors of this tumor cell subset. Our findings indicate the importance of future studies determining the value of cell surface pro-N-cadherin as: 1) a biomarker for TNBC recurrence and 2) a therapeutic target for eliminating chemo-residual disease.
尽管大多数三阴性乳腺癌（TNBC）患者最初对化疗有反应，但残留肿瘤细胞经常持续存在并驱动肿瘤复发生长。我们实验室和其他机构之前的研究表明，TNBC具有异质性，由化疗敏感和化疗耐药的肿瘤细胞亚群组成。在当前的研究中，我们研究了化疗耐药TNBC的侵袭行为，并试图确定化疗残留TNBC中的侵袭标志物。
使用Transwell侵袭实验和实验性转移模型研究了体外短期化疗处理后存活的TNBC肿瘤细胞的侵袭行为。通过PCR评估促进侵袭的粘附分子神经钙黏蛋白（N-cadherin）的mRNA表达水平。通过免疫印迹和流式细胞术评估N-cadherin及其前体形式（pro-N-cadherin）的表达。对新辅助化疗治疗前后患者的肿瘤进行pro-N-cadherin免疫组化。
与未处理的肿瘤细胞相比，短期化疗处理后存活的TNBC细胞表现出增强的侵袭行为和在转移部位定植的能力。化疗耐药细胞的侵袭行为与其前体N-cadherin（pro-N-cadherin）细胞表面表达增加有关。一种针对N-cadherin前体结构域的抗体可抑制化疗耐药TNBC细胞的侵袭。为了开始在人体中验证我们的发现，我们发现化疗后患者细胞表面pro-N-cadherin（+）肿瘤细胞的百分比增加。
短期化疗处理后存活的TNBC细胞比总体肿瘤细胞更具侵袭性。细胞表面pro-N-cadherin表达与该肿瘤细胞亚群的侵袭和化疗耐药行为相关。我们的发现表明未来研究确定细胞表面pro-N-cadherin价值的重要性：1）作为TNBC复发的生物标志物；2）作为消除化疗残留疾病的治疗靶点。
