Akt抑制剂MK-2206在缺氧环境下对结肠癌SW480细胞增殖、侵袭的影响

目的:探讨Akt抑制剂MK-2206在缺氧环境下对人结肠癌SW480细胞增殖、侵袭的影响。方法:根据CCK-8实验结果选择CoCl2和MK-2206的浓度,最后分成空白组、MK-2206组、CoCl2组、MK-2206+CoCl2组;Transwell小室实验检测四组细胞的迁移和侵袭能力;RT-PCR法检测各细胞组中Akt、mTOR、HIF-1α的mRNA表达水平;Western blot技术检测各细胞组中Akt、p-Akt、mTOR、p-mTOR、HIF-1α蛋白表达的差异性情况。结果:CoCl2诱导的缺氧环境可以促进SW480细胞的侵袭、迁移(P＜0.05),同时能够促进HIF-1α的mRNA和蛋白表达(P＜0.05),但是低浓度范围内的CoCl2对SW480细胞增殖活性无明显影响(P＞0.05);MK-2206可以在体外的常氧和缺氧环境中抑制SW480细胞的增殖活性和侵袭、迁移能力(P＜0.05);MK-2206能在体外的常氧环境下抑制SW480细胞的Akt、mTOR、HIF-1α的mRNA表达(P＜0.05),缺氧环境无明显作用;同时MK-2206能够在常氧和缺氧环境中显著降低p-Akt、p-mTOR、HIF-1α的蛋白表达水平(P＜0.05)。 结论:Akt抑制剂MK-2206可以在体外的常氧和缺氧环境下抑制SW480细胞的增殖活性和侵袭能力,但缺氧环境可能会弱化MK-2206对SW480细胞迁移的抑制作用。     

Src酪氨酸激酶抑制剂dasatinib对人食管鳞癌细胞KYSE180生长及凋亡的影响

目的:探讨Src酪氨酸激酶抑制剂dasatinib对人食管鳞癌细胞生长和凋亡的影响及其相关机制.方法:采用蛋白质印迹法检测食管鳞癌细胞株KYSE180、EC109、KYSE30和人永生化食管上皮细胞株SHEE中总Src和磷酸化Src激酶的表达.用不同剂量的Src酪氨酸激酶抑制剂dasatinib作用KYSE180细胞后,分别采用MTT法、FCM法、蛋白质印迹法和裸鼠皮下移植瘤实验观察dasatinib对KYSE180细胞Src激酶的抑制作用,以及对细胞增殖、细胞周期、细胞凋亡和裸鼠皮下移植瘤的影响.结果:KYSE180、EC109和KYSE30细胞中Src激酶显著活化,而在SHEE细胞中未见活化Src激酶.Dasatinib可显著抑制KYSE180细胞增殖,阻碍细胞G1/S期转换,促进细胞凋亡,并上调caspase 3、cytochrome C和Bax等凋亡相关蛋白的表达.另外,dasatinib可显著抑制裸鼠皮下KYSE180细胞移植瘤的生长.结论:Dasatinib可通过抑制食管鳞癌细胞增殖、促进细胞凋亡以及影响细胞周期等机制,抑制食管鳞癌细胞皮下移植瘤的生长,因此其可望成为治疗食管鳞癌的一个有效药物.     

Akt抑制剂MK-2206清除衰老神经母细胞瘤细胞的实验研究

摘 要：［目的］ 探讨Akt抑制剂MK-2206清除衰老神经母细胞瘤细胞IMR-32的效果及可能机制。［方法］ 极光激酶A抑制剂MLN8237处理神经母细胞瘤细胞系IMR-32，利用衰老相关β半乳糖苷酶（SA-β-gal）染色检测细胞状态、免疫荧光法检测组蛋白磷酸化和甲基化情况评估细胞衰老状况。CCK-8检测不同浓度MK-2206及MK-2206与MLN8237联合对IMR-32细胞增殖的影响，流式细胞术检测细胞凋亡状况。Western blot法检测MK-2206与MLN8237联合用药对IMR-32细胞 Akt、p-Akt、STAT3和N-Myc表达的影响。［结果］ MLN8237作用IMR-32细胞后，细胞核体积明显增大，细胞呈现大而扁平的衰老状态，细胞蓝染数显著增多；组氨酸 H3 Ser10磷酸化水平和组氨酸 H3 K9甲基化水平显著性升高。Western blot显示衰老IMR-32细胞内磷酸化Akt和STAT3蛋白显著性上调。10μmol/L MK-2206干预衰老细胞72h和96h后细胞存活率分别为（80.13±5.30）%、（74.29±4.06）%，较不干预衰老细胞组显著性下降。在MK-2206与MLN8237联合作用下细胞出现明显凋亡，凋亡率为（15.70±0.97）%，而不干预衰老细胞组细胞凋亡率为（8.81±1.33）%。同时两药联合组胞内p-Akt、STAT3和N-Myc蛋白显著性下调。［结论］ MK-2206可能通过抑制衰老神经母细胞瘤细胞内p-Akt，下调STAT3和N-Myc蛋白的机制，诱导细胞凋亡，从而达到清除MLN8237诱导的衰老细胞目的。     

miR-6883-3p靶向CHD1L抑制肝癌细胞的恶性表型

目的:寻找可靶向调控恶性肿瘤相关染色质解旋因子CHD1L的miRNAs分子,确证该调控模式对肝癌细胞恶性表型的影响。方法:通过生物信息学分析预测并筛选可靶向结合CHD1L的miRNAs,实时荧光定量PCR（qRT-PCR）及蛋白印迹分析（Western Blot）方法验证所筛选的miRNAs 对肝癌细胞CHD1L表达的影响,明确可转录后调控CHD1L表达的关键miRNA分子;qRT-PCR检测肝癌组织中miRNAs和CHD1L的表达,并对其表达进行相关性分析;MTS、细胞划痕、Transwell迁移实验验证目标miRNA分子对肝癌细胞恶性表型的影响。结果:生物信息学分析结果显示miR-6883-3p可显著下调肝癌细胞CHD1L表达。双荧光素酶报告实验检测结果证明miR-6883-3p可直接靶向结合CHD1L 3' UTR端。临床肝癌组织样本qRT-PCR检测及统计学分析结果显示CHD1L高表达于肝癌组织,而miR-6883-3p则高表达于癌旁组织,二者表达呈负相关。miR-6883-3p 模拟物（mimic）可明显抑制肝癌细胞增殖、促进细胞凋亡、抑制细胞迁移;而miR-6883-3p抑制剂（inhibitor）可显著促进肝癌细胞增殖、促进细胞迁移。 与对照组（Mock）相比,miR-6883-3p mimic组肝癌细胞内ALB表达则随着CHD1L表达的下调而增加,HNF-4α及AFP随着CHD1L表达的下调而减少,反之亦然。结论:miR-6883-3p通过靶向调控CHD1L表达,抑制肝癌细胞的恶性表型。     

lncRNA MIR205HG通过调控miR-122-5p促进食管鳞状细胞癌细胞的增殖和侵袭

目的:探究长链非编码RNA(lncRNA) MIR205HG对食管鳞状细胞癌细胞增殖和侵袭的影响及其作用机制。方法:RT-PCR检测食管鳞状细胞癌组织以及癌旁组织中MIR205HG的表达量;CCK-8实验检测MIR205HG对食管鳞状细胞癌细胞Eca-109和TE-10增殖的影响;Western blot实验检测侵袭相关蛋白MMP-1和MMP-9以及血管内皮生长因子（VEGF）的蛋白表达水平。结果:结果显示,MIR205HG在食管鳞状细胞癌组织中的表达量显著高于癌旁组织的表达量（P＜0.05）;与转染对照si-RNA相比,当细胞转染si-MIR205HG时,MIR205HG的表达量显著被抑制（P＜0.05）;干扰MIR205HG显著抑制食管鳞状细胞癌细胞Eca-109和TE-10的增殖和侵袭（P＜0.05）;此外,si-MIR205HG促进miR-122-5p的表达,且MIR205HG与miR-122-5p表达量呈负相关（P＜0.05）;进一步的研究结果表明,抑制miR-122-5p逆转si-MIR205HG对TE-10细胞增殖和侵袭的抑制作用（P＜0.05）。结论:MIR205HG能够促进食管鳞状细胞癌细胞的增殖和侵袭,其作用机制是通过调控miR-122-5p来实现的,这一结果能够为食管鳞状细胞癌的临床治疗和诊断提供分子基础。     

三氧化二砷对人肝癌细胞作用的研究

目的 :应用体外培养的肝癌细胞株 (SMMC 772 1)观察砷剂 (As2 O3)的凋亡诱导作用。方法 :采用MTT法检测As2 O3对肝癌细胞增殖的影响 ,DNA电泳及流式细胞仪检测不同浓度As2 O3作用不同时间对肝癌细胞的凋亡诱导作用及细胞周期的影响。结果 :As2 O3抑制肝癌细胞的增殖并具有剂量 -时效关系 ;As2 O3可使肝癌细胞周期改变 ,与浓度有关 ,与作用时间未见明显关系 ;As2 O3诱导肝癌细胞发生凋亡 ,并与浓度、时间有关。结论 :As2 O3能抑制肝癌细胞增殖 ,改变肝癌细胞周期 ,诱导肝癌细胞凋亡     

Mig-6基因表达对肝癌细胞增殖和凋亡的影响

目的:研究Mig-6对肝癌细胞增殖和凋亡的影响,以探讨Mig-6在肝癌中的作用机制。方法:采用Mig-6过表达质粒和siRNA转染肝癌细胞,使用Real-time PCR和Western Blot法检测转染后的过表达或沉默效果;CCK-8实验检测细胞增殖水平的变化;流式细胞仪检测细胞凋亡百分比的变化;蛋白免疫印迹检测相关蛋白的表达变化。结果:转染Mig-6能抑制肝癌细胞的增殖,促进肝癌细胞的凋亡;干扰Mig-6能促进肝癌细胞的增殖,抑制肝癌细胞的凋亡。上调Mig-6能增加肝癌细胞Caspase-3 的活性,抑制P-ERK的磷酸化;干扰下调Mig-6能抑制肝癌细胞Caspase-3 的活性,增加P-ERK的磷酸化。结论:在肝癌细胞中,Mig-6表现出抑制细胞增殖及促进细胞凋亡的作用,该作用可能与Mig-6能增加Caspase-3 的活性,同时抑制P-ERK的表达有关。     

ICE基因转染联合化疗药物杀伤肝癌细胞的研究

目的：研究人ICE基因转染联合化疗药物诱导体外杀伤肝癌细胞的作用。方法：应用电穿孔法将构建成功含有目的基因的逆转录病毒载体pLXSN-hICE导入包装细胞系PA317，筛选G418抗性克隆，并将其病毒上清转入肝癌细胞株HepG2，DNA提取、电泳观察；采用^3H-TDR掺入法观察、分析化疗药物卡铂对肝癌细胞株SMMC7721及转入相应目的基因后的SMMC7721-ICE，SMMC7721-反义hICE，SMMC7721-neo细胞株体外增殖的影响。结果：ICE基因转染可诱导HepG2形成具有凋亡特征的梯状DNA；在卡铂低浓度诱导下，与对照细胞相比SMMC7721-hICE细胞株体外增殖明显受抑。结论：人ICE基因转染可直接诱导肝癌细胞株HepG2凋亡，明显提高肝癌细胞SMMC7721对化疗药物卡铂杀伤的敏感性，ICE基因转染联合化疗药物诱导极大增强了对肝癌细胞的杀伤作用，可能是治疗肝癌一个有前途的方案。     

降脂药对肝癌细胞增殖、侵袭及中性粒细胞外诱捕网形成的影响

目的 探讨降脂药对肝癌细胞增殖、干性特征、迁移、侵袭和中性粒细胞外诱捕网（NETs）形成的作用。方法 下调ASPP2或HMGCR基因建立胆固醇合成增加或减弱的小鼠肝癌细胞Hepa1-6，分别用辛伐他汀和黄连素两种降脂药处理。CCK-8和平板克隆实验检测肝癌细胞增殖能力；低吸附板成球和qRT-PCR分析细胞干性特征和相关基因表达；划痕和Transwell实验分析细胞迁移、侵袭的能力。免疫荧光染色分析NETs形成。结果 降脂药可显著抑制Hepa1-6细胞贴壁和成球生长及干性基因表达（P<0.001）；显著抑制Hepa1-6细胞迁移和侵袭能力（P<0.001）；显著抑制中性粒细胞诱导的Hepa1-6细胞侵袭和NETs的生成（P<0.001）。结论 降脂药通过抑制肝癌细胞的干性特征和NETs形成，抑制肝癌细胞增殖和转移，是治疗肝癌转移的一种潜在方式。     

三氧化二砷对人肝癌细胞作用的研究

目的：应用体外培养的肝癌细胞株(SMMC-7721)观察砷剂(As2O3)的凋亡诱导作用。方法：采用MTT法检测As2O3对肝癌细胞增殖的影响，DNA电泳及流式细胞仪检测不同浓度As2O3作用不同时间对肝癌细胞的凋亡诱导作用及细胞周期的影响。结果：As2O3抑制肝癌细胞的增殖并具有剂量-时效关系；As2O3可使肝癌细胞周期改变，与浓度有关，与作用时间未见明显关系；As2O3诱导肝癌细胞发生凋亡，并与浓度、时间有关。结论：As2O3能抑制肝癌细胞增殖，改变肝癌细胞周期，诱导肝癌细胞凋亡。     

CircLASP1 silence strengthens the therapeutic effects of MK-2206 on nasopharyngeal cancer through upregulating miR-625

Therapeutic effects of MK-2206 are largely limited due to the complexity of the pathogenesis of nasopharyngeal cancer (NPC). Here, we aimed to investigate whether and how circLASP1 is involved in the therapeutic effects of MK-2206 on NPC. We showed circLASP1 was increased while miR-625 was decreased in NPC tissues and cell lines. CircLASP1 silence strengthened the therapeutic effects of MK-2206 via suppressing NPC cell proliferation and inducing autophagy and apoptosis in vitro. In mechanism analyses, we found that circLASP1 indirectly released AKT by directly binding to miR-625 in NPC cells, and miR-625 acted as a tumor suppressor in NPC and activated cell autophagy through inhibiting the AKT/mTOR pathway. Most importantly, knockdown of circLASP1 was revealed to enhance the therapeutic effects of MK-2206 on NPC in vivo. Our results suggest that the circLASP1/miR-625 axis is involved the therapeutic effects of MK-2206 on NPC by regulating autophagy, proliferation, and apoptosis through the AKT/mTOR pathway. miR-625 is involved in NPC tumorigenesis.     

MK-2206, an Akt inhibitor,enhances carboplatinum/paclitaxel efficacy in gastric cancer cell lines

Background Several molecularly-targeted agents are being evaluated in gastric cancer cell lines. In this study we evaluated the synergistic potential of MK-2206, an oral potent allosteric Akt inhibitor, in combination with chemotherapeutic agents in human gastric cancer cell lines. Materials and Methods We evaluated effects of MK-2206 on cell growth and cell signaling using a panel of gastric cancer cell lines AGS, SNU-1 and SNU 16. The analysis of drug combinations was conducted by using CellTiter-Blue™ Cell Viability Assay which yielded the combination index (CI). MK-2206 and representative chemotherapy agent were further evaluated regarding their effects on Akt inhibition and downstream targets using western blots probed with the appropriate antibodies. We assessed the combination of MK-2206 and chemotherapy in three different treatment sequences. Results We demonstrated in vitro synergistic efficacy of MK-2206 when combined with carboplatinum and paclitaxel in the three cell lines examined. Efficacy was dose dependent. We assessed the combination of MK-2206 and carboplatinum/paclitaxel in three different treatment sequences; 24 h of exposure to combination chemotherapy followed by a 48 h exposure to MK-2206 resulted in the highest synergistic antiproliferative effect in all cell lines. On the other hand, the reverse sequence (MK-2206 followed by chemotherapy) and the concurrent treatment schedule were slightly synergistic or additive as well. The effects of MK-2206 on p-Akt and other downstream targets was reported. Conclusions Our findings suggest that Akt inhibition augments the efficacy of existing gastric cancer therapeutics (carboplatinum and paclitaxel); thus, MK-2206 is a promising agent to treat gastric cancer patients who receive these cytotoxic agents. The magnitude of synergy depended on the treatment sequence; a schedule of MK-2206 dosed before or concurrently with chemotherapy was not as effective as being dosed after chemotherapy. Further experiments addressing MK-2206’s mechanism of action in combination with chemotherapy are needed.     

Dual Targeting of the Akt/mTOR Signaling Pathway Inhibits Castration-Resistant Prostate Cancer in a Genetically Engineered Mouse Model

Although the prognosis for clinically localized prostate cancer is now favorable, there are still no curative treatments for castration-resistant prostate cancer (CRPC) and, therefore, it remains fatal. In this study, we investigate a new therapeutic approach for treatment of CRPC, which involves dual targeting of a major signaling pathway that is frequently deregulated in the disease. We found that dual targeting of the Akt and mTOR signaling pathways with their respective inhibitors, MK-2206 and ridaforolimus (MK-8669), is highly effective for inhibiting CRPC in preclinical studies in vivo using a refined genetically engineered mouse model of the disease. The efficacy of the combination treatment contrasts with their limited efficacy as single agents, since delivery of MK-2206 or MK-8669 individually had a modest impact in vivo on the overall tumor phenotype. In human prostate cancer cell lines, although not in the mouse model, the synergistic actions of MK-2206 and ridaforolimus (MK-8669) are due in part to limiting the mTORC2 feedback activation of Akt. Moreover, the effects of these drugs are mediated by inhibition of cellular proliferation via the retinoblastoma (Rb) pathway. Our findings suggest that dual targeting of the Akt and mTOR signaling pathways using MK-2206 and ridaforolimus (MK-8669) may be effective for treatment of CRPC, particularly for patients with deregulated Rb pathway activity. Cancer Res; 72(17); 4483-93. ?2012 AACR.     

The AKT Inhibitor MK-2206 is Cytotoxic in Hepatocarcinoma Cells Displaying Hyperphosphorylated AKT-1 and Synergizes with Conventional Chemotherapy

Hepatocellular carcinoma (HCC) is one of the most common potentially lethal human malignancies worldwide. Advanced or recurrent HCC is frequently resistant to conventional chemotherapeutic agents and radiation. Therefore, targeted agents with tolerable toxicity are mandatory to improve HCC therapy and prognosis. In this neoplasia, the PI3K/Akt signaling network has been frequently shown to be aberrantly up-regulated. To evaluate whether Akt could represent a target for treatment of HCC, we studied the effects of the allosteric Akt inhibitor, MK-2206, on a panel of HCC cell lines characterized by different levels of Akt-1 activation. The inhibitor decreased cell viability and induced cell cycle arrest in the G₀/G₁ phase of the cell cycle, with a higher efficacy in cells with hyperphosphorylated Akt-1. Moreover, MK-2206 induced apoptosis, as documented by Annexin V labeling, and also caused autophagy, as evidenced by increased levels of the autophagy marker LC3A/B. Autophagy was shown to be a protective mechanism against MK-2206 cytotoxicity. MK-2206 down-regulated, in a concentration-dependent manner, the phosphorylation levels of Akt-1 synergizedand its downstream targets, GSK3 α/β and FOXO3A. MK-2206 synergized with doxorubicin, a chemotherapeutic drug widely used for HCC treatment. Our findings suggest that the use of Akt inhibitors, either alone or in combination with doxorubicin, may be considered as an attractive therapeutic regimen for the treatment of HCC.     

Chemopreventive allylthiopyridazine derivatives induce apoptosis in SK-Hep-1 hepatocarcinoma cells through a caspase-3-dependent mechanism

Dietary organosulphur compounds including diallylsulphide, a component of garlic oil, were shown to inhibit the proliferation of tumour cells. Since hepatocellular carcinoma is one of the most lethal malignancies and there is no effective preventive measure to date, we wished to pursue the chemopreventive potential of the synthetic allylthiopyridazine derivatives (K compounds) on hepatocarcinoma cells. Here, we report that the K compounds efficiently inhibited SK-Hep-1 cell proliferation through induction of apoptosis. Increased chain length at the 3-position of allylthiopyridazine ring improved the potency of growth inhibition. K compounds downregulated Bcl-2, while Bax remained unchanged, reducing the ratio of Bcl-2 to Bax. We also provide evidence that the K compound-induced apoptosis involves cytochrome c release and caspase-3 activation. These results suggest that the allythiopyridazine derivatives, especially 3-propoxy-6-allylthiopyridazine, induce apoptosis in SK-Hep-1 cells through a caspase-3-dependent mechanism, which may contribute to the chemopreventive function for hepatocellular carcinoma.     

Mutant PIK3CA controls DUSP1-dependent ERK 1/2 activity to confer response to AKT target therapy

Background:

Alterations in the phosphoinositide 3-kinase/AKT/mammalian target of rapamycin (PI3K/AKT/mTOR) signalling pathway are frequent in urothelial bladder cancer (BLCA) and thus provide a potential target for novel therapeutic strategies. We investigated the efficacy of the AKT inhibitor MK-2206 in BLCA and the molecular determinants that predict therapy response.

Methods:

Biochemical and functional effects of the AKT inhibitor MK-2206 were analysed on a panel of 11 BLCA cell lines possessing different genetic alterations. Cell viability (CellTiter-Blue, cell counts), apoptosis (caspase 3/7 activity) and cell cycle progression (EdU incorporation) were analysed to determine effects on cell growth and proliferation. cDNA or siRNA transfections were used to manipulate the expression of specific proteins such as wild-type or mutant PIK3CA, DUSP1 or CREB. For in vivo analysis, the chicken chorioallantoic membrane model was utilised and tumours were characterised by weight and biochemically for the expression of Ki-67 and AKT phosphorylation.

Results:

Treatment with MK-2206 suppressed AKT and S6K1 but not 4E-BP1 phosphorylation in all cell lines. Functionally, only cell lines bearing mutations in the hotspot helical domain of PIK3CA were sensitive to the drug, independent of other genetic alterations in the PI3K or MAPK signalling pathway. Following MK-2206 treatment, the presence of mutant PIK3CA resulted in an increase in DUSP1 expression that induced a decrease in ERK 1/2 phosphorylation. Manipulating the expression of mutant or wild-type PIK3CA or DUSP1 confirmed that this mechanism is responsible for the induction of apoptosis and the inhibition of tumour proliferation in vitro and in vivo, to sensitise cells to AKT target therapy.

Conclusion or interpretation:

PIK3CA mutations confer sensitivity to AKT target therapy in BLCA by regulating DUSP1 expression and subsequent ERK1/2 dephosphorylation and can potentially serve as a stratifying biomarker for treatment.     

FLT3-ITD confers resistance to the PI3K/Akt pathway inhibitors by protecting the mTOR/4EBP1/Mcl-1 pathway through STAT5 activation in acute myeloid leukemia

FLT3-ITD and FLT3-TKD are the most frequent tyrosine kinase mutations in acute myeloid leukemia (AML), with the former associated with poor prognosis. Here, we show that the PI3K inhibitor GDC-0941 or the Akt inhibitor MK-2206 induced apoptosis through the mitochondria-mediated intrinsic pathway more efficiently in hematopoietic 32D cells driven by FLT3-TKD (32D/TKD) than FLT3-ITD (32D/ITD), which robustly activated STAT5. The resistance to GDC-0941 and MK-2206 was gained by expression of the constitutively activated STAT5 mutant STAT5A1*6 in 32D/TKD cells, while it was abrogated by the STAT5 inhibitor pimozide in 32D/ITD cells or FLT3-ITD-expressing human leukemic MV4–11 cells. GDC-0941 or MK-2206 induced dephosphorylation of 4EBP1 more conspicuously in 32D/TKD than in 32D/ITD, which was prevented or augmented by STAT5A1*6 or pimozide, respectively, and correlated with downregulation of the eIF4E/eIF4G complex formation and Mcl-1 expression. Furthermore, exogenous expression of Mcl-1 endowed resistance to GDC-0941 and MK-2206 on 32D/TKD cells. Finally, it was confirmed in primary AML cells with FLT3-ITD that pimozide enhanced 4EBP1 dephosphorylation and Mcl-1 downregulation to augment cytotoxicity of GDC-0941. These data suggest that the robust STAT5 activation by FLT3-ITD protects cells treated with the PI3K/Akt pathway inhibitors from apoptosis by maintaining Mcl-1 expression through the mTORC1/4EBP1/eIF4E pathway.     

A parallel-arm phase I trial of the humanised anti-IGF-1R antibody dalotuzumab in combination with the AKT inhibitor MK-2206, the mTOR inhibitor ridaforolimus,or the NOTCH inhibitor MK-0752, in patients with advanced solid tumours

Background:

Two strategies to interrogate the insulin growth factor 1 receptor (IGF-1R) pathway were investigated: vertical inhibition with dalotuzumab and MK-2206 or ridaforolimus to potentiate PI3K pathway targeting and horizontal cross-talk inhibition with dalotuzumab and MK-0752 to exert effects against cellular proliferation, angiogenesis, and stem cell propagation.

Methods:

A phase I, multi-cohort dose escalation study was conducted in patients with advanced solid tumours. Patients received dalotuzumab (10 mg kg^–1) and escalating doses of MK-2206 (90–200 mg) or escalating doses of dalotuzumab (7.5–10 mg kg^–1) and MK-0752 (1800 mg) weekly. Upon maximum tolerated dose determination, patients with low-RAS signature, high-IGF1 expression ovarian cancer were randomised to dalotuzumab/MK-2206 versus dalotuzumab/ridaforolimus, whereas patients with high IGF1/low IGF2 expression colorectal cancer received dalotuzumab/MK-0752.

Results:

A total of 47 patients were enrolled: 29 in part A (18 in the dalotuzumab/MK-2206 arm and 11 in the dalotuzumab/MK-0752 arm) and 18 in part B (6 in each arm). Dose-limiting toxicities (DLTs) for dalotuzumab/MK-2206 included grade 4 neutropenia and grade 3 serum sickness-like reaction, maculopapular rash, and gastrointestinal inflammation. For dalotuzumab/MK-0752, DLTs included grade 3 dehydration, rash, and diarrhoea. Seven patients remained on study for >4 cycles.

Conclusions:

Dalotuzumab/MK-2206 and dalotuzumab/MK-0752 combinations were tolerable. Further developments of prospectively validated predictive biomarkers to aid in patient selection for anti-IGF-1R therapies are needed.     

eEF-2 kinase dictates cross-talk between autophagy and apoptosis induced by Akt Inhibition, thereby modulating cytotoxicity of novel Akt inhibitor MK-2206

Inhibition of the survival kinase Akt can trigger apoptosis, and also has been found to activate autophagy, which may confound tumor attack. In this study, we investigated regulatory mechanisms through which apoptosis and autophagy were modulated in tumor cells subjected to Akt inhibition by MK-2206, the first allosteric small molecule inhibitor of Akt to enter clinical development. In human glioma cells, Akt inhibition by MK-2206 or siRNA-mediated attenuation strongly activated autophagy, whereas silencing of eukaryotic elongation factor-2 (eEF-2) kinase, a protein synthesis regulator, blunted this autophagic response. Suppression of MK-2206-induced autophagy by eEF-2 silencing was accompanied by a promotion of apoptotic cell death. Similarly, siRNA-mediated inhibition of eEF-2 kinase potentiated the efficacy of MK-2206 against glioma cells. Together, these results showed that blunting autophagy and augmenting apoptosis by inhibition of eEF-2 kinase could modulate the sensitivity of glioma cells to Akt inhibition. Our findings suggest that targeting eEF-2 kinase may reinforce the antitumor efficacy of Akt inhibitors such as MK-2206.