Montefiore Medical Center, Bronx, New York, USA.
Clin Cancer Res. 2012 May 1;18(9):2534-44. doi: 10.1158/1078-0432.CCR-11-1407. Epub 2012 Feb 14.
The mTOR pathway is constitutively activated in diffuse large B-cell lymphoma (DLBCL). mTOR inhibitors have activity in DLBCL, although response rates remain low. We evaluated DLBCL cell lines with differential resistance to the mTOR inhibitor rapamycin: (i) to identify gene expression profile(s) (GEP) associated with resistance to rapamycin, (ii) to understand mechanisms of rapamycin resistance, and (iii) to identify compounds likely to synergize with mTOR inhibitor.
We sought to identify a GEP of mTOR inhibitor resistance by stratification of eight DLBCL cell lines with respect to response to rapamycin. Then, using pathway analysis and connectivity mapping, we sought targets likely accounting for this resistance and compounds likely to overcome it. We then evaluated two compounds thus identified for their potential to synergize with rapamycin in DLBCL and confirmed mechanisms of activity with standard immunoassays.
We identified a GEP capable of reliably distinguishing rapamycin-resistant from rapamycin-sensitive DLBCL cell lines. Pathway analysis identified Akt as central to the differentially expressed gene network. Connectivity mapping identified compounds targeting Akt as having a high likelihood of reversing the GEP associated with mTOR inhibitor resistance. Nelfinavir and MK-2206, chosen for their Akt-inhibitory properties, yielded synergistic inhibition of cell viability in combination with rapamycin in DLBCL cell lines, and potently inhibited phosphorylation of Akt and downstream targets of activated mTOR.
GEP identifies DLBCL subsets resistant to mTOR inhibitor therapy. Combined targeting of mTOR and Akt suppresses activation of key components of the Akt/mTOR pathway and results in synergistic cytotoxicity. These findings are readily adaptable to clinical trials.
mTOR 通路在弥漫性大 B 细胞淋巴瘤（DLBCL）中持续激活。尽管 mTOR 抑制剂在 DLBCL 中有活性，但反应率仍然较低。我们评估了对 mTOR 抑制剂雷帕霉素具有不同耐药性的 DLBCL 细胞系：（i）鉴定与雷帕霉素耐药相关的基因表达谱（GEP），（ii）了解雷帕霉素耐药的机制，以及（iii）鉴定可能与 mTOR 抑制剂协同作用的化合物。
我们试图通过对 8 种 DLBCL 细胞系进行雷帕霉素反应分层，来鉴定 mTOR 抑制剂耐药的 GEP。然后，我们使用途径分析和连通性映射，寻找可能导致这种耐药的靶标以及可能克服这种耐药的化合物。然后，我们评估了两种因此而确定的化合物在 DLBCL 中与雷帕霉素协同作用的潜力，并通过标准免疫测定法证实了其活性机制。
我们鉴定了一个 GEP，能够可靠地区分雷帕霉素耐药和雷帕霉素敏感的 DLBCL 细胞系。途径分析确定 Akt 是差异表达基因网络的核心。连通性映射确定了针对 Akt 的化合物作为逆转与 mTOR 抑制剂耐药相关的 GEP 具有很高的可能性。选择具有 Akt 抑制特性的奈非那韦和 MK-2206，用于其与雷帕霉素联合在 DLBCL 细胞系中具有协同抑制细胞活力的作用，并能有效抑制 Akt 的磷酸化及其下游激活的 mTOR 靶标。
GEP 鉴定出对 mTOR 抑制剂治疗有耐药性的 DLBCL 亚群。联合靶向 mTOR 和 Akt 抑制 Akt/mTOR 通路的关键成分的激活，并导致协同细胞毒性。这些发现很容易适应临床试验。
