Emerging data support the rationale of combined therapies in advanced melanoma. Specifically, the combined use of drugs with different mechanisms of action can reduce the probability of selecting resistant clones. To identify agents active against melanoma cells, we screened a library of 349 anti-cancer compounds, currently in clinical use or trials, and selected PIK-75, an inhibitor of the phosphatidylinositol 3-kinase/protein kinase B (PI3K/AKT) pathway, as the 'top active' drug. PIK-75 was then used alone or in combination with vemurafenib, the first BRAF inhibitor approved for patients with melanoma harboring BRAF mutations. We identified a combined dose of PIK-75 and vemurafenib that inhibited both the PI3K/AKT and mitogen-activated protein kinase pathways, thereby overcoming any compensatory activation. In view of the important tumor suppressor function induced by restoring expression of microRNA (miR)-126 in metastatic melanoma cells, we examined whether miR-126 has a synergistic role when included in a triple combination alongside PIK-75 and vemurafenib. We found that enforced expression of miR-126 (which alone can reduce tumorigenicity) significantly increased PIK-75 activity when used as either a single agent or in combination with vemurafenib. Interestingly, PIK-75 proved to be effective against early passage cell lines derived from patients' biopsies and on melanoma cell lines resistant to either vemurafenib or dabrafenib, thus suggesting that it potentially has the capability to overcome drug resistance. Finally, the synergistic role played by miR-126 in combination with vemurafenib and/or PIK-75 was demonstrated in vivo in mouse xenograft models, in which tumor growth inhibition was associated with increased apoptosis. These results not only show the efficacy of PIK-75 and vemurafenib co-treatment but also indicate that restoration of miR-126 expression in advanced melanoma can enhance their antitumor activity, which may possibly allow dose reduction to decrease adverse events without reducing the therapeutic benefits.

中文翻译：

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miR-126和MAPK / PI3K抑制剂对转移性黑色素瘤的联合作用。

新兴数据支持晚期黑色素瘤联合治疗的基本原理。具体而言，具有不同作用机制的药物的联合使用可降低选择抗性克隆的可能性。为了鉴定对黑色素瘤细胞有活性的药物，我们筛选了目前正在临床或试验中的349种抗癌化合物文库，并选择了PIK-75（磷脂酰肌醇3-激酶/蛋白激酶B（PI3K / AKT）途径的抑制剂） ，作为“顶级活性”药物。然后将PIK-75单独使用或与vemurafenib结合使用，vemurafenib是第一种被批准用于携带BRAF突变的黑色素瘤患者的BRAF抑制剂。我们确定了抑制PI3K / AKT和丝裂原激活的蛋白激酶途径的PIK-75和维拉非尼的联合剂量，从而克服了任何补偿性激活。鉴于通过恢复转移性黑素瘤细胞中microRNA（miR）-126的表达诱导的重要肿瘤抑制功能，我们检查了miR-126与PIK-75和vemurafenib并入三联组合时是否具有协同作用。我们发现，当作为单一药物或与维罗非尼联合使用时，miR-126的强制表达（仅能减少致瘤性）可显着提高PIK-75的活性。有趣的是，PIK-75被证明对源自患者活组织检查的早期传代细胞系以及对维罗非尼或达布拉非尼具有耐药性的黑色素瘤细胞系有效，因此表明它具有潜在的克服耐药性的能力。最后，miR-126与维拉非尼和/或PIK-75联合发挥的协同作用已在小鼠异种移植模型中体内证实，其中肿瘤生长抑制与凋亡增加有关。这些结果不仅表明PIK-75和维拉非尼联合治疗的功效，而且表明晚期黑素瘤中miR-126表达的恢复可以增强其抗肿瘤活性，这可能允许降低剂量以减少不良反应而不降低治疗益处。 。