miR-200c Mediates Suppression of Anoikis Resistance by Targeting an Autocrine Sig

描述(申请人提供)：该项目的长期目标是为传统化疗药物无效或复发的三阴性乳腺癌患者确定一种新的治疗方法。由于缺乏激素受体，患有这种特殊亚型乳腺癌的患者的治疗选择极其有限。因此，确定驱动这种癌症的分子机制并确定新的治疗策略是当务之急。来自我的实验室和其他实验室的初步数据表明，miR-200C抑制迁移、侵袭、对微管靶向剂的耐药性和癌症干细胞表型。我已经证明，将miR-200C恢复为三重阴性的乳腺癌细胞株也会抑制它们对失巢凋亡的耐药性。失巢凋亡是一种细胞凋亡形式，当细胞失去与细胞外基质的相互作用时，它被认为是肿瘤转移的生理屏障。当癌细胞在血管或淋巴管中形成栓子，但没有基质黏附时，对失巢细胞的抵抗可能允许癌细胞在体循环中存活。我发现miR-200C直接针对多种癌症类型中涉及失巢凋亡抵抗的细胞表面受体，神经营养性酪氨酸受体激酶B(TrkB)。此外，TrkB的配体神经营养素3(NTF3)在3‘非编码区有两个预测的miR-200C结合位点。综上所述，这些数据导致了我的假设，即miR-200C通过靶向TrkB/NTF3信号通路来增强乳腺癌细胞的失巢凋亡敏感性。以下具体目标验证了这一假设。具体目标1：确定TrkB/NTF3中的一个自分泌信号环是否有助于miR-200C抑制乳腺癌细胞的失巢凋亡耐药。特定目的2：确定乳腺癌患者标本中miR-200C的缺失是否与TrkB和NTF3的表达相关。具体目标3：在体内研究miR-200C对侵袭性乳腺癌细胞失巢凋亡的增敏作用 转移模型。通过进一步了解miR-200C如何影响乳腺癌的失巢抵抗，我们更接近于将这种有影响力的miRNA作为一种治疗选择。 与公共卫生相关：乳腺癌是女性一生中面临的第二大致命癌症，对于对传统化疗无效或复发的三阴性乳腺癌患者来说，没有真正的治疗选择。我们已经确定了一种miRNA，miR-200C，它能够使细胞对固有的细胞程序敏感，当细胞脱离连接时，这种程序会导致细胞死亡。通过使用miR-200C作为一种非传统的化疗药物，我们希望通过在癌细胞能够定植转移部位之前杀死它们来防止转移。

DESCRIPTION (provided by applicant): The long-term goal of this project is to identify a new treatment for patients with triple negative breast cancer who have not responded to, or relapsed while on, traditional chemotherapeutics. Patients with this particular subtype of breast cancer have extremely limited therapeutic options due to the absence of hormone receptors. Thus, determining the molecular mechanisms that drive this cancer and identifying new therapeutic strategies is a high priority. Preliminary data from my lab and others demonstrates that miR-200c suppresses migration, invasion, resistance to microtubule targeting agents and a cancer stem cell phenotype. I have demonstrated that restoring miR-200c to triple negative breast cancer cell lines also suppresses their resistance to anoikis. Anoikis is a form of apoptosis that is initiated when the cells lose their interactions with the extracellular matrix, and it has been suggested as a physiological barrier to metastasis. Resistance to anoikis may allow survival of the carcinoma cells during systemic circulation, when they form emboli in the vasculature or lymphatics but are deprived of matrix adhesion. I have found that miR-200c directly targets a cell surface receptor implicated in anoikis resistance in multiple cancer types, neurotrophic tyrosine receptor kinase B (TrkB). Furthermore, neurotrophin 3 (NTF3), a ligand for TrkB has 2 predicted miR-200c binding sites in the 3' UTR. Taken together, this data leads to my hypothesis that miR-200c enhances anoikis sensitivity in breast cancer cells through targeting of a TrkB/NTF3 signaling pathway. The following specific aims test this hypothesis. Specific aim 1: Determine if an autocrine signaling loop in TrkB/NTF3 contributes to the ability of miR- 200c to suppress anoikis resistance in breast cancer cells. Specific aim 2: Determine if loss of miR-200c correlates with expression of TrkB and NTF3 in breast cancer patient samples. Specific aim 3: Study the ability of miR- 200c to sensitize aggressive breast cancer cells to anoikis in an in vivo model of metastasis. By furthering our understanding of how miR-200c affects anoikis resistance in breast cancer, we move closer to the development of this influential miRNA as a therapeutic option. PUBLIC HEALTH RELEVANCE: Breast cancer is the second most deadly cancer a woman will face in her lifetime, with no real treatment options for patients with triple negative breast cancer who do not respond to, or relapse while on, traditional chemotherapy. We have identified a miRNA, miR-200c, that is able to sensitize cells to an inherent cellular program that drives them to die when they are unattached. By utilizing miR-200c as a non-traditional chemotherapeutic, we hope to prevent metastasis by killing cancer cells before they are able to colonize metastatic sites.