Department of Bioengineering, University of California, Berkeley, CA, USA.
Mol Cancer. 2010 Feb 10;9:35. doi: 10.1186/1476-4598-9-35.
Neuroblastoma is a pediatric malignancy characterized by tremendous clinical heterogeneity, in which some tumors are extremely aggressive while others spontaneously differentiate into benign forms. Because the degree of differentiation correlates with prognosis, and because differentiating agents such as retinoic acid (RA) have proven to decrease mortality, much effort has been devoted to identifying critical regulators of neuroblastoma differentiation in the cellular microenvironment, including cues encoded in the extracellular matrix (ECM). While signaling between tumor cells and the ECM is classically regarded to be based purely on biochemical recognition of ECM ligands by specific cellular receptors, a number of recent studies have made it increasingly clear that the biophysical properties of the ECM may also play an important role in this cross-talk. Given that RA-mediated neuroblastoma differentiation is accompanied by profound changes in cell morphology and neurite extension, both of which presumably rely upon mechanotransductive signaling systems, it occurred to us that mechanical cues from the ECM might also influence RA-mediated differentiation, which in turn might regulate clinically-relevant aspects of neuroblastoma biology. In this study, we tested this hypothesis by subjecting a series of neuroblastoma culture models to ECM microenvironments of varying mechanical stiffness and examined the regulatory role of ECM stiffness in proliferation, differentiation, and expression of tumor markers. We find that increasing ECM stiffness enhances neuritogenesis and suppresses cell proliferation. Remarkably, increasing ECM stiffness also reduces expression of N-Myc, a transcription factor involved in multiple aspects of oncogenic proliferation that is used for evaluating prognosis and clinical grading of neuroblastoma. Furthermore, the addition of RA enhances all of these effects for all ECM stiffnesses tested. Together, our data strongly support the notion that the mechanical signals from the cellular microenvironment influence neuroblastoma differentiation and do so synergistically with RA. These observations support further investigation of the role of microenvironmental mechanical signals in neuroblastoma proliferation and differentiation and suggest that pharmacological agents that modulate the underlying mechanotransductive signaling pathways may have a role in neuroblastoma therapy.
神经母细胞瘤是一种儿科恶性肿瘤，其临床表现具有巨大的异质性，一些肿瘤极具侵袭性，而另一些则自发分化为良性形式。由于分化程度与预后相关，并且已经证明视黄酸（RA）等分化剂可以降低死亡率，因此人们投入了大量精力来识别细胞微环境中神经母细胞瘤分化的关键调节因子，包括细胞外基质（ECM）中编码的线索。虽然肿瘤细胞与 ECM 之间的信号传递通常被认为纯粹基于特定细胞受体对 ECM 配体的生化识别，但最近的一些研究越来越清楚地表明，ECM 的生物物理特性也可能在这种交流中发挥重要作用。鉴于 RA 介导的神经母细胞瘤分化伴随着细胞形态和神经突延伸的深刻变化，这两种变化都推测依赖于机械转导信号系统，因此我们认为 ECM 中的机械线索也可能影响 RA 介导的分化，进而可能调节神经母细胞瘤生物学中与临床相关的方面。在这项研究中，我们通过将一系列神经母细胞瘤培养模型置于不同机械硬度的 ECM 微环境中，检验了 ECM 硬度在增殖、分化和肿瘤标志物表达中的调节作用，从而验证了这一假设。我们发现，增加 ECM 硬度会促进神经突生成并抑制细胞增殖。值得注意的是，增加 ECM 硬度还会降低参与多种致癌增殖方面的转录因子 N-Myc 的表达，N-Myc 是用于评估神经母细胞瘤预后和临床分级的标志物。此外，RA 的添加增强了所有这些在所有测试的 ECM 硬度下的作用。总之，我们的数据强烈支持这样一种观点，即细胞微环境中的机械信号会影响神经母细胞瘤的分化，并且与 RA 协同作用。这些观察结果支持进一步研究微环境机械信号在神经母细胞瘤增殖和分化中的作用，并表明调节潜在机械转导信号通路的药理学药物可能在神经母细胞瘤治疗中发挥作用。
