Department of Chemical Engineering, University of Massachusetts, Amherst, MA 01003, USA.
Department of Chemical Engineering, University of Massachusetts, Amherst, MA 01003, USA; Materials Research Science and Engineering Center, University of Massachusetts, Amherst, MA 01003, USA; Molecular and Cellular Biology Graduate Program, University of Massachusetts, Amherst, MA 01003, USA.
Biomaterials. 2014 Jul;35(22):5749-59. doi: 10.1016/j.biomaterials.2014.03.058. Epub 2014 Apr 13.
Tumor progression is coincident with mechanochemical changes in the extracellular matrix (ECM). We hypothesized that tumor stroma stiffening, alongside a shift in the ECM composition from a basement membrane-like microenvironment toward a dense network of collagen-rich fibers during tumorigenesis, confers resistance to otherwise powerful chemotherapeutics. To test this hypothesis, we created a high-throughput drug screening platform based on our poly(ethylene glycol)-phosphorylcholine (PEG-PC) hydrogel system, and customized it to capture the stiffness and integrin-binding profile of in vivo tumors. We report that the efficacy of a Raf kinase inhibitor, sorafenib, is reduced on stiff, collagen-rich microenvironments, independent of ROCK activity. Instead, sustained activation of JNK mediated this resistance, and combining a JNK inhibitor with sorafenib eliminated stiffness-mediated resistance in triple negative breast cancer cells. Surprisingly, neither ERK nor p38 appears to mediate sorafenib resistance, and instead, either ERK or p38 inhibition rescued sorafenib resistance during JNK inhibition, suggesting negative crosstalk between these signaling pathways on stiff, collagen-rich environments. Overall, we discovered that β1 integrin and its downstream effector JNK mediate sorafenib resistance during tumor stiffening. These results also highlight the need for more advanced cell culture platforms, such as our high-throughput PEG-PC system, with which to screen chemotherapeutics.
肿瘤的进展与细胞外基质（ECM）的力化学变化同时发生。我们假设，肿瘤基质变硬，以及 ECM 组成从基底膜样微环境向富含胶原纤维的致密网络转变，在肿瘤发生过程中赋予了对其他强大化疗药物的抗性。为了验证这一假设，我们基于聚乙二醇-磷酸胆碱（PEG-PC）水凝胶系统创建了一个高通量药物筛选平台，并对其进行了定制，以捕捉体内肿瘤的硬度和整合素结合谱。我们报告说，Raf 激酶抑制剂索拉非尼的疗效在坚硬、富含胶原的微环境中降低，而与 ROCK 活性无关。相反，JNK 的持续激活介导了这种抗性，并且将 JNK 抑制剂与索拉非尼联合使用可消除三阴性乳腺癌细胞中因硬度引起的耐药性。令人惊讶的是，ERK 和 p38 似乎都不介导索拉非尼耐药性，而是在 JNK 抑制期间，ERK 或 p38 抑制可挽救索拉非尼耐药性，这表明在坚硬、富含胶原的环境中这些信号通路之间存在负性交叉对话。总的来说，我们发现β1 整合素及其下游效应物 JNK 在肿瘤变硬过程中介导了索拉非尼耐药性。这些结果还强调了需要更先进的细胞培养平台，如我们的高通量 PEG-PC 系统，以筛选化疗药物。
