A phase 2 study of MK-2206 in patients with incurable adenoid cystic carcinoma (Alliance A091104)

BACKGROUND

Recurrent/metastatic adenoid cystic carcinoma (ACC) is a rare, incurable disease. MYB is a putative oncogenic driver in ACC that is often overexpressed through an MYB-NFIB rearrangement. The authors hypothesized that AKT inhibition with the allosteric inhibitor MK-2206 could decrease MYB expression and induce tumor regression in patients with incurable ACC (ClinicalTrials.gov identifier NCT01604772).

METHODS

Patients with progressive, incurable ACC were enrolled and received MK-2206 150 mg weekly; escalation to 200 mg was allowed. The primary end point was confirmed response. Secondary end points were progression-free survival, overall survival, and safety. An exploratory analysis evaluating the effect of MK-2206 on MYB expression was conducted in a subset of patients.

RESULTS

Sixteen patients were enrolled, and 14 were evaluable for efficacy. No confirmed responses were observed. Thirteen patients had stable disease, and one had disease progression as their best response. The median progression-free survival was 9.7 months (95% CI, 3.8-11.8 months), and the median overall survival was 18.0 months (95% CI, 11.8-29.9 months). Nine of 16 patients (56%) had at least one grade 3 treatment-related adverse event, and the most common were rash (38%), fatigue (19%), decreased lymphocyte count (13%), and hyperglycemia (13%). Twelve of 14 tumors (86%) had detectable MYB expression by immunohistochemistry, and seven of 14 tumors (50%) had an MYB-NFIB gene rearrangement. Serial biopsies revealed decreased MYB levels with MK-2206 in four of five patients.

CONCLUSIONS

MK-2206 failed to induce clinical responses in patients with incurable ACC. AKT inhibition may diminish MYB protein levels, although the effect was highly variable among patients. Novel approaches to target MYB in ACC are needed.

AKT inhibition sensitizes acute leukemia cells to S63845-induced apoptosis

The MCL1 inhibitors are undergoing clinical testing for multiple leukemia. However, because that MCL1 inhibition has on-target hematopoietic, hepatic and cardiac toxicities, there is substantial interest in finding agents can sensitize leukemia cells to the MCL1 inhibitors. Here we describe that the AKT inhibitors MK-2206 and Gsk690693 sensitize multiple leukemia cells to the MCL1 inhibitor S63845. Further experiments demonstrate that MK-2206 and Gsk690693 sensitize S63845 through the mitochondrial apoptosis pathway. Moreover, MK-2206 downregulates the anti-apoptotic protein BCLX_L and induces the BH3-only pro-apoptotic protein BAD dephosphorylation and mitochondrial translocation. Knockdown of BAD significantly inhibits MK-2206-induced sensitization to S63845. Thus, our results suggest that MK-2206 sensitizes multiple leukemia cells to S63845-induced apoptosis, with the mechanisms involving BAD dephosphorylation and BCLX_L downregulation.

The AKT inhibitor, MK-2206, attenuates ABCG2-mediated drug resistance in lung and colon cancer cells

Introduction: The overexpression of ATP-binding cassette (ABC) transporters, ABCB1 and ABCG2, are two of the major mediators of multidrug resistance (MDR) in cancers. Although multiple ABCB1 and ABCG2 inhibitors have been developed and some have undergone evaluation in clinical trials, none have been clinically approved. The compound, MK-2206, an inhibitor of the protein kinases AKT1/2/3, is undergoing evaluation in multiple clinical trials for the treatment of certain types of cancers, including those resistant to erlotinib. In this in vitro study, we conducted in vitro experiments to determine if MK-2206 attenuates multidrug resistance in cancer cells overexpressing the ABCB1 or ABCG2 transporter. Methodology: The efficacy of MK-2206 (0.03-1 μM), in combination with the ABCB1 transporter sub-strates doxorubicin and paclitaxel, and ABCG2 transporter substrates mitoxantrone, SN-38 and topotecan, were determined in the cancer cell lines, KB-C2 and SW620/Ad300, which overexpress the ABCB1 transporter or H460/MX20 and S1-M1-80, which overexpress the ABCG2 transporter, respectively. The expression level and the localization of ABCG2 transporter on the cancer cells membranes were determined using western blot and immunofluorescence assays, respectively, following the incubation of cells with MK-2206. Finally, the interaction between MK-2206 and human ABCG2 transporter was predicted using computer-aided molecular modeling. Results: MK-2206 significantly increased the efficacy of anticancer compounds that were substrates for the ABCG2 but not the ABCB1 transporter. MK-2206 alone (0.03-1 μM) did not significantly alter the viability of H460/MX20 and S1-M1-80 cancer cells, which overexpress the ABCG2 transporter, compared to cells incubated with vehicle. However, MK-2206 (0.3 and 1 μM) significantly increased the anticancer efficacy of mitoxantrone, SN-38 and topotecan, in H460/MX20 and S1-M1-80 cancer cells, as indicated by a significant decrease in their IC50 values, compared to cells incubated with vehicle. MK-2206 significantly increased the basal activity of the ABCG2 ATPase (EC50 = 0.46 μM) but did not significantly alter its expression level and sub-localization in the membrane. The molecular modeling results suggested that MK-2206 binds to the active pocket of the ABCG2 transporter, by a hydrogen bond, hydrophobic interactions and π-π stacking. Conclusion: These in vitro data indicated that MK-2206 surmounts resistance to mitoxantrone, SN-38 and topotecan in cancer cells overexpressing the ABCG2 transporter. If these results can be translated to humans, it is possible that MK-2206 could be used to surmount MDR in cancer cells overexpressing the ABCG2 transporter.

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.

Combined BCL-2 and PI3K/AKT Pathway Inhibition in KMT2A-Rearranged Acute B-Lymphoblastic Leukemia Cells

Numerous hematologic neoplasms, including acute B-lymphoblastic leukemia (B-ALL), are characterized by overexpression of anti-apoptotic BCL-2 family proteins. Despite the high clinical efficacy of the specific BCL-2 inhibitor venetoclax in acute myeloid leukemia (AML) and chronic lymphocytic leukemia (CLL), dose limitation and resistance argue for the early exploration of rational combination strategies. Recent data indicated that BCL-2 inhibition in B-ALL with KMT2A rearrangements is a promising intervention option; however, combinatorial approaches have not been in focus so far. The PI3K/AKT pathway has emerged as a possible target structure due to multiple interactions with the apoptosis cascade as well as relevant dysregulation in B-ALL. Herein, we demonstrate for the first time that combined BCL-2 and PI3K/AKT inhibition has synergistic anti-proliferative effects on B-ALL cell lines. Of note, all tested combinations (venetoclax + PI3K inhibitors idelalisib or BKM-120, as well as AKT inhibitors MK-2206 or perifosine) achieved comparable anti-leukemic effects. In a detailed analysis of apoptotic processes, among the PI3K/AKT inhibitors only perifosine resulted in an increased rate of apoptotic cells. Furthermore, the combination of venetoclax and perifosine synergistically enhanced the activity of the intrinsic apoptosis pathway. Subsequent gene expression studies identified the pro-apoptotic gene BBC3 as a possible player in synergistic action. All combinatorial approaches additionally modulated extrinsic apoptosis pathway genes. The present study provides rational combination strategies involving selective BCL-2 and PI3K/AKT inhibition in B-ALL cell lines. Furthermore, we identified a potential mechanistic background of the synergistic activity of combined venetoclax and perifosine application.

Combined treatment with ruxolitinib and MK-2206 inhibits the JAK2/STAT5 and PI3K/AKT pathways via apoptosis in MDA-MB-231 breast cancer cell line

BACKGROUND

Due to deficiencies in the expression of hormone receptors, such as PR, ER and HER2, it is challenging to treat triple-negative breast cancer, which does not respond to single targeted therapy. Ruxolitinib is a Janus kinase (JAK)1/JAK2 inhibitor. MK-2206 is an allosteric AKT inhibitor. Due to the limited activities of ruxolitinib and MK-2206 for monotherapy, the need for cotreatment with other drugs has emerged. This study is the first to examine the effects of ruxolitinib and MK-2206 cotreatment on apoptosis and JAK2/STAT5 and PI3K/AKT signaling in MDA-MB-231 breast cancer cells. Additionally, this work aimed to decrease the side effects of ruxolitinib and increase its anticancer effects with MK-2206 cotreatment.

METHODS AND RESULTS

Cell viability was reduced in a dose- and time-dependent manner after exposure to ruxolitinib, MK-2206 or both for 48 h, as shown by MTT assay. Ruxolitinib had a synergistic antiproliferative effect, as demonstrated by colony formation and wound healing assays. The effects of ruxolitinib, MK-2206 and their combination on apoptosis, as well as PI3K/AKT and JAK/STAT signaling, were examined by western blot analyses. Cotreatment with ruxolitinib and MK-2206 reduced proliferation with the dual inhibition of JAK2/STAT5 and PI3K/AKT signaling by decreasing PI3K, AKT, JAK2, STAT5, Caspase-9, Caspase-7, PARP, c-Myc, and Bcl-2 and increasing P53 and PTEN protein expression.

CONCLUSIONS

Our results revealed the roles of P53 and PTEN in the regulation of apoptosis and the PI3K/AKT and JAK2/STAT5 signaling pathways. The dual inhibition of JAK2/STAT5 and PI3K/AKT may reduce metastasis by decreasing tumor cell survival.

Studies on Biological and Molecular Effects of Small-Molecule Kinase Inhibitors on Human Glioblastoma Cells and Organotypic Brain Slices

Glioblastoma is the most common and aggressive primary brain tumor. Multiple genetic and epigenetic alterations in several major signaling pathways—including the phosphoinositide 3-kinases (PI3K)/AKT/mTOR and the Raf/MEK/ERK pathway—could be found. We therefore aimed to investigate the biological and molecular effects of small-molecule kinase inhibitors that may interfere with those pathways. For this purpose, patient-derived glioblastoma cells were challenged with dactolisib, ipatasertib, MK-2206, regorafenib, or trametinib. To determine the effects of the small-molecule kinase inhibitors, assays of cell proliferation and apoptosis and immunoblot analyses were performed. To further investigate the effects of ipatasertib on organotypic brain slices harboring glioblastoma cells, the tumor growth was estimated. In addition, the network activity in brain slices was assessed by electrophysiological field potential recordings. Multi-kinase inhibitor regorafenib and both MK-2206 and dactolisib were very effective in all preclinical tumor models, while with respect to trametinib, two cell lines were found to be highly resistant. Only in HROG05 cells, ipatasertib showed anti-tumoral effects in vitro and in organotypic brain slices. Additionally, ipatasertib diminished synchronous network activity in organotypic brain slices. Overall, our data suggest that ipatasertib was only effective in selected tumor models, while especially regorafenib and MK-2206 presented a uniform response pattern.

Phosphoproteomics of primary AML patient samples reveals rationale for AKT combination therapy and p53 context to overcome selinexor resistance

Acute myeloid leukemia (AML) is a heterogeneous disease with variable patient responses to therapy. Selinexor, an inhibitor of nuclear export, has shown promising clinical activity for AML. To identify the molecular context for monotherapy sensitivity as well as rational drug combinations, we profile selinexor signaling responses using phosphoproteomics in primary AML patient samples and cell lines. Functional phosphosite scoring reveals that p53 function is required for selinexor sensitivity consistent with enhanced efficacy of selinexor in combination with the MDM2 inhibitor nutlin-3a. Moreover, combining selinexor with the AKT inhibitor MK-2206 overcomes dysregulated AKT-FOXO3 signaling in resistant cells, resulting in synergistic anti-proliferative effects. Using high-throughput spatial proteomics to profile subcellular compartments, we measure global proteome and phospho-proteome dynamics, providing direct evidence of nuclear translocation of FOXO3 upon combination treatment. Our data demonstrate the potential of phosphoproteomics and functional phosphorylation site scoring to successfully pinpoint key targetable signaling hubs for rational drug combinations.

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Phosphoproteomics with functional scoring uncovers context for selinexor sensitivity

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Functional p53 correlates with selinexor sensitivity, which is enhanced by nutlin-3a

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Dysregulated AKT-FOXO3 drives selinexor resistance, which is overcome with MK-2206

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Spatial proteomics reveals selinexor-induced nucleocytoplasmic protein shuttling

LGR6 promotes glioblastoma malignancy and chemoresistance by activating the Akt signaling pathway

Chemoresistance is the primary cause of the poor outcome of glioblastoma multiforme (GBM) therapy. Leucine-rich repeat-containing G-protein coupled receptor 6 (LGR6) is involved in the growth and proliferation of several types of cancer, including gastric cancer and ovarian cancer. Therefore, the aim of the present study was to investigate the role of LGR6 in GBM malignancy and chemoresistance. Cell counting kit-8 and Matrigel®-Transwell assays were conducted to assess GBM cell viability and invasion. The effect of LGR6 on cell cycle progression and activation of Akt signaling was analyzed by performing propidium iodide staining and western blotting, respectively. The results demonstrated that LGR6, a microRNA-1236-3p target candidate, promoted GBM cell viability and invasion, and mediated temozolomide sensitivity in SHG-44 and U251 GBM cells. In addition, LGR6 triggered the activation of the Akt signaling pathway during GBM progression. Collectively, the results of the present study suggested that LGR6 promoted GBM malignancy and chemoresistance, at least in part, by activating the Akt signaling pathway. The results may aid with the identification of a novel therapeutic target and strategy for GBM.

The Synergistic Inhibitory Effect of Combining MK-2206 and AZD 6244 in MARIMO Cells Harboring a Calreticulin Gene Mutation

INTRODUCTION

Somatic mutations in the calreticulin (CALR) gene occur in most myeloproliferative neoplasm (MPN) patients who lack Janus kinase 2 or thrombopoietin receptor (MPL) mutations, but the molecular pathogenesis of MPN with mutated CALR is unclear, which limited the further treatment for CALR gene mutant patients.

OBJECTIVES

Previous studies showed that CALR mutations not only activated serine/threonine protein kinase (AKT) in primary mouse bone marrow cells but also mitogen-activated protein kinases (MAPKs) in MARIMO cells harboring a heterozygous 61-bp deletion in CALR exon 9, which were responsible for mutant CALR cell survival, respectively. Hence, we aimed to initially explore the mechanism of AKT activation and observe the synergistic inhibitory effect of combining AKT (MK-2206) and MAPK kinase (AZD 6244) inhibitors in MARIMO cells.

METHODS

We detected the expression of phosphorylated AKT in MARIMO cells treated with inhibitors for 24 or 48 h by western blotting and analyzed cell proliferation, cell cycle, and apoptosis by flow cytometry. We further examined the synergistic inhibitory effect of combining MK-2206 and AZD 6244 in MARIMO cells using the median effect principle of Chou and Talalay.

RESULTS

We found that the AKT was activated in MARIMO cells, and blocking its activity significantly inhibited MARIMO cell growth with downregulation of cyclin D and E, and accelerated cell apoptosis by decreasing Bcl-2 but increasing Bax and cleaved caspase-3 levels in a dose-dependent manner. Further analysis showed that AKT activation was dependent on mammalian target of rapamycin but not on the JAK signaling pathway in MARIMO cells, displaying that inhibition of JAK activity by ruxolitinib (RUX) did not decrease the AKT phosphorylation. Furthermore, the combination of MK-2206 and AZD 6244 produced a significantly synergistic inhibitory effect on MARIMO cells.

CONCLUSIONS

AKT activation is a feature of MARIMO cells and co-targeting of AKT and MAPKs signaling pathways synergistically inhibits MARIMO cell growth.

Downregulation of ATXN3 Enhances the Sensitivity to AKT Inhibitors (Perifosine or MK-2206), but Decreases the Sensitivity to Chemotherapeutic Drugs (Etoposide or Cisplatin) in Neuroblastoma Cells

Background

Chemotherapy resistance is the major cause of failure in neuroblastoma (NB) treatment. ATXN3 has been linked to various types of cancer and neurodegenerative diseases; however, its roles in NB have not been established. The aim of our study was to explore the role of ATXN3 in the cell death induced by AKT inhibitor (perifosine or MK-2206) or chemotherapy drugs (etoposide or cisplatin) in NB cells.

Methods

The expressions of ATXN3 and BCL-2 family members were detected by Western blot. Cell survival was evaluated by CCK8, cell confluence was measured by IncuCyte, and apoptosis was detected by flow cytometry. AS and BE2 were treated with AKT inhibitors or chemotherapeutics, respectively.

Results

Downregulation of ATXN3 did not block, but significantly increased the perifosine/MK-2206-induced cell death. Among the BCL-2 family members, the expression of pro-apoptotic protein BIM and anti-proapoptotic protein Bcl-xl expression increased significantly when ATXN3 was down-regulated. Downregulation of BIM protected NB cells from the combination of perifosine/MK-2206 and ATXN3 downregulation. Downregulation of ATXN3 did not increase, but decrease the sensitivity of NB cells to etoposide/cisplatin, and knockdown of Bcl-xl attenuated this decrease in sensitivity.

Conclusion

Downregulation of ATXN3 enhanced AKT inhibitors (perifosine or MK-2206) induced cell death by BIM, but decreased the cell death induced by chemotherapeutic drugs (etoposide or cisplatin) via Bcl-xl. The expression of ATXN3 may be an indicator in selecting different treatment regimen.

Central and peripheral emetic loci contribute to vomiting evoked by the Akt inhibitor MK-2206 in the least shrew model of emesis

Akt (protein kinase B) signaling is frequently activated in diverse cancers. Akt inhibitors such as perifosine and MK-2206 have been evaluated as potential cancer chemotherapeutics. Although both drugs are generally well tolerated, among their most common side-effects vomiting is a major concern. Here we investigated whether these Akt inhibitors evoke emesis in the least shrew model of vomiting. Indeed, both perifosine and MK-2206 induced vomiting with maximal efficacies of 90% at 50 mg/kg (i.p.) and 100% at 10 mg/kg (i.p.), respectively. MK-2206 (10 mg/kg, i.p.) increased c-Fos immunoreactivity both centrally in the shrew brainstem dorsal vagal complex (DVC) emetic nuclei, and peripherally in the jejunum. MK-2206 also evoked phosphorylation of extracellular signal-regulated kinase 1/2 (ERK1/2) in both the DVC emetic nuclei and the enteric nervous system in the jejunum. The ERK1/2 inhibitor U0126 suppressed MK-2206-induced emesis dose-dependently. We then evaluated the suppressive efficacy of diverse antiemetics against MK-2206-evoked vomiting including antagonists/inhibitors of the: L-type Ca²⁺ channel (nifedipine at 2.5 mg/kg, subcutaneously (s.c.)); glycogen synthase kinase 3 (GSK-3) (AR-A014418 at 10 mg/kg and SB216763 at 0.25 mg/kg, i.p.); 5-hydroxytryptamine 5-HT₃ receptor (palonosetron at 0.5 mg/kg, s.c.); substance P neurokinin NK₁ receptor (netupitant at 10 mg/kg, i.p.) and dopamine D_2/3 receptor (sulpride at 8 mg/kg, s.c.). All tested antagonists/blockers attenuated emetic parameters to varying degrees. In sum, this is the first study to demonstrate how pharmacological inhibition of Akt evokes vomiting via both central and peripheral mechanisms, a process which involves multiple emetic receptors.

Combined Application of Pan-AKT Inhibitor MK-2206 and BCL-2 Antagonist Venetoclax in B-Cell Precursor Acute Lymphoblastic Leukemia

Aberrant PI3K/AKT signaling is a hallmark of acute B-lymphoblastic leukemia (B-ALL) resulting in increased tumor cell proliferation and apoptosis deficiency. While previous AKT inhibitors struggled with selectivity, MK-2206 promises meticulous pan-AKT targeting with proven anti-tumor activity. We herein, characterize the effect of MK-2206 on B-ALL cell lines and primary samples and investigate potential synergistic effects with BCL-2 inhibitor venetoclax to overcome limitations in apoptosis induction. MK-2206 incubation reduced AKT phosphorylation and influenced downstream signaling activity. Interestingly, after MK-2206 mono application tumor cell proliferation and metabolic activity were diminished significantly independently of basal AKT phosphorylation. Morphological changes but no induction of apoptosis was detected in the observed cell lines. In contrast, primary samples cultivated in a protective microenvironment showed a decrease in vital cells. Combined MK-2206 and venetoclax incubation resulted in partially synergistic anti-proliferative effects independently of application sequence in SEM and RS4;11 cell lines. Venetoclax-mediated apoptosis was not intensified by addition of MK-2206. Functional assessment of BCL-2 inhibition via Bax translocation assay revealed slightly increased pro-apoptotic signaling after combined MK-2206 and venetoclax incubation. In summary, we demonstrate that the pan-AKT inhibitor MK-2206 potently blocks B-ALL cell proliferation and for the first time characterize the synergistic effect of combined MK-2206 and venetoclax treatment in B-ALL.

Gene Expression Profiling Identifies Akt as a Target for Radiosensitization in Gastric Cancer Cells

Background

Despite the important role of radiotherapy in cancer treatment, a subset of patients responds poorly to treatment majorly due to radioresistance. Particularly the role of radiotherapy has not been established in gastric cancer (GC). Herein, we aimed to identify a radiosensitivity gene signature and to discover relevant targets to enhance radiosensitivity in GC cells.

Methods

An oligonucleotide microarray (containing 22,740 probes) was performed in 12 GC cell lines prior to radiation. A clonogenic assay was performed to evaluate the survival fraction at 2 Gy (SF2) as a surrogate marker for radiosensitivity. Genes differentially expressed (fold change > 6, q-value < 0.025) were identified between radiosensitive and radioresistant cell lines, and quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR) was performed for validation. Gene set and pathway analyses were performed using Ingenuity Pathway Analysis (IPA).

Results

Radiosensitive (SF2 < 0.4) and radioresistant cell lines (SF2 ≥ 0.6) exhibited a marked difference in gene expression. We identified 68 genes that are differentially expressed between radiosensitive and radioresistant cell lines. The identified genes showed interactions via AKT, HIF1A, TGFB1, and TP53, and their functions were associated with the genetic networks associated with cellular growth and proliferation, cellular movement, and cell cycle. The Akt signaling pathway exhibited the highest association with radiosensitivity. Combinatorial treatment with MK-2206, an allosteric Akt inhibitor, and radiotherapy significantly increased cell death compared with radiotherapy alone in two radioresistant cell lines (YCC-2 and YCC-16).

Conclusion

We identified a GC-specific radiosensitivity gene signature and suggest that the Akt signaling pathway could serve as a therapeutic target for GC radiosensitization.

KLF5-mediated COX2 upregulation contributes to tumorigenesis driven by PTEN deficiency

Tumor suppressor gene PTEN is frequently mutated in a wide variety of cancers. However, the downstream targets or signal transduction pathways of PTEN remain not fully understood. By analyzing Pten-null mouse embryonic fibroblasts (MEFs) cell lines and their isogenic counterparts, we showed that loss of PTEN led to increased cyclooxygenase2 (COX2) expression in an AKT-independent manner. Moreover, we demonstrated that PTEN deficiency promotes the transcription of COX2 via upregulation of the transcription factor Krüppel-like factor 5 (KLF5). Knocked down the expression of COX2 suppressed proliferation, migration and tumoral growth of Pten-null cells. Further experiments revealed that COX2 enhanced Pten-null MEFs growth and migration through upregulation of NADPH oxidase 4 (NOX4). In addition, MK-2206, a specific inhibitor of AKT, in combination with celecoxib, a COX2 inhibitor, strongly inhibited Pten-deficient cell growth. We concluded that KLF5/COX2/NOX4 signaling pathway is critical for cell growth and migration caused by the loss of PTEN, and the combination of MK-2206 and celecoxib may be an effective new approach to treating PTEN deficiency related tumors.

Dysregulation in Akt/mTOR/HIF-1 signaling identified by proteo-transcriptomics of SARS-CoV-2 infected cells

How severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infections engage cellular host pathways and innate immunity in infected cells remains largely elusive. We performed an integrative proteo-transcriptomics analysis in SARS-CoV-2 infected Huh7 cells to map the cellular response to the invading virus over time. We identified four pathways, ErbB, HIF-1, mTOR and TNF signaling, among others that were markedly modulated during the course of the SARS-CoV-2 infection in vitro. Western blot validation of the downstream effector molecules of these pathways revealed a dose-dependent activation of Akt, mTOR, S6K1 and 4E-BP1 at 24 hours post infection (hpi). However, we found a significant inhibition of HIF-1α through 24hpi and 48hpi of the infection, suggesting a crosstalk between the SARS-CoV-2 and the Akt/mTOR/HIF-1 signaling pathways. Inhibition of the mTOR signaling pathway using Akt inhibitor MK-2206 showed a significant reduction in virus production. Further investigations are required to better understand the molecular sequelae in order to guide potential therapy in the management of severe coronavirus disease 2019 (COVID-19) patients.

Akt Inhibition Is Associated With Favorable Immune Profile Changes Within the Tumor Microenvironment of Hormone Receptor Positive, HER2 Negative Breast Cancer

Background: The PI3K/Akt/mTOR pathway in part impacts tumorigenesis through modulation of host immune activity. To assess the effects of Akt inhibition on the tumor micro-environment (TME), we analyzed tumor tissue from patients with operable hormone receptor positive, HER2 negative breast cancer (BC) treated on a presurgical trial with the Akt inhibitor MK-2206. Methods: Quantitative multiplex immunofluorescence (qmIF) was performed using CD3, CD8, CD4, FOXP3, CD68, and pancytokeratin on biopsy and surgical specimens of MK-2206 and untreated, control patients. nanoString was performed on surgical specimens to assess mRNA expression from MK-2206-treated vs. control patients. Results: Increased CD3+CD8+ density was observed in post vs. pre-treatment tissue in the MK-2206-treated vs. control patients (87 vs. 0.2%, p < 0.05). MK-2206 was associated with greater expression of interferon signaling genes (e.g., IFI6, p < 0.05) and lower expression of myeloid genes (CD163, p < 0.05) on differential expression and gene set enrichment analyses. Greater expression of pro-apoptotic genes (e.g., BAD) were associated with MK-2206 treatment (p < 0.05). Conclusion: Akt inhibition in operable BC was associated with a favorable immune profile in the TME, including increased CD3+CD8+ density and greater expression of interferon genes. Additional studies are warranted, as this may provide rationale for combining Akt inhibition with immunotherapy.

Integrin αvβ3-Akt signalling plays a role in radioresistance of melanoma

Melanoma is a deadly type of skin cancer that is particularly difficult to treat owing to its resistance to radiation therapy. Here, we attempted to determine the key proteins responsible for melanoma radioresistance, with the aim of improving disease response to radiation therapy. Two melanoma cell lines, SK-Mel5 and SK-Mel28, with different radiosensitivities were analysed via RNA-Seq (Quant-Seq) and target proteins with higher abundance in the more radioresistant cell line, SK-Mel28, identified. Among these proteins, integrin αvβ3, a well-known molecule in cell adhesion, was selected for analysis. Treatment of SK-Mel28 cells with cilengitide, an integrin αvβ3 inhibitor, as well as γ-irradiation resulted in more significant cell death than γ-irradiation alone. In addition, Akt, a downstream signal transducer of integrin αvβ3, showed high basic activation in SK-Mel28 and was significantly decreased upon co-treatment with cilengitide and γ-irradiation. MK-2206, an Akt inhibitor, exerted similar effects on the SK-Mel28 cell line following γ-irradiation. Our results collectively demonstrate that the integrin αvβ3-Akt signalling pathway contributes to radioresistance in SK-Mel28 cells, which may be manipulated to improve therapeutic options for melanoma.

Akt inhibitor MK-2206 reduces pancreatic cancer cell viability and increases the efficacy of gemcitabine

The PI3K/Akt pathway is an attractive therapeutic target in the treatment of pancreatic cancer, as it was demonstrated to be aberrantly regulated in pancreatic cancer cells. The present study aimed to investigate the therapeutic potential of the novel Akt inhibitor MK-2206 in human pancreatic cancer cell lines. Pancreatic cancer cell survival following MK-2206 treatment was assessed using the Cell Counting Kit-8 (CCK-8) assay, colony formation and determination of the apoptotic rate by flow cytometry following annexin-V-fluorescein isothiocyanate/propidium iodide staining. The effects of MK-2206 alone or in combination with gemcitabine on pancreatic cell proliferation were assessed using the CCK-8 assay. Western blotting was used to examine the effects of the two drugs on Akt protein expression. The results demonstrated that MK-2206 inhibited the proliferation and induced apoptosis of the Mia PaCa-2 and Panc-1 pancreatic cancer cell lines. In addition, CCK-8 cytotoxicity test showed that combined administration of MK-2206 with gemcitabine enhanced the cytotoxic efficacy of gemcitabine. Furthermore, a low dose of MK-2206 (1 µM) combined with gemcitabine was enough to inhibit Akt phosphorylation. Taken together, these results provided some insight into the underlying mechanism of the anticancer effects of MK-2206 on pancreatic cancer cells.

Combination of Rapamycin and MK-2206 Induced Cell Death via Autophagy and Necroptosis in MYCN-Amplified Neuroblastoma Cell Lines

Neuroblastoma (NB) is the most common pediatric malignant extracranial solid tumor. Despite multi-modality therapies, the emergence of drug resistance is an obstacle in the treatment of high-risk NB patients (with MYCN amplification). In our previous study, we found that rapamycin and MK-2206 synergistically induced cell death in MYCN-amplified cell lines but the mechanisms remained unclear. In our present study, either 3-MA or necroatatin-1 blocked the cell death induced by rapamycin and MK-2206, but z-VAD-fmk did not block this cell death. The expressions of autophagy markers (ATG5, ATG7, Beclin-1, LC3 B) and the necroptosis marker RIPK3 increased and another necroptosis marker RIPK1 decreased after the combination treatment of rapamycin and MK-2206, and were accompanied by the morphological characteristics of autophagy and necroptosis. In NB xenograft tumor tissues, the expressions of autophagy and necroptosis markers were consistent with observations in vitro. These data suggested that autophagy and necroptosis contributed to the cell death induced by rapamycin and MK-2206 in NB cells. To understand the role of MYCN in this process, MYCN expression was downregulated in MYCN-amplified cell lines (NGP, BE2) using siRNAs and was upregulated in MYCN non-amplified cell lines (AS, SY5Y) using plasmid. We found the cell death induced by rapamycin and MK-2206 was MYCN-dependent. We also found that the metabolic activity in NB cells was correlated with the expression level of MYCN. This study delineates the role of MYCN in the cell death induced by combination treatment of rapamycin and MK-2206 in MYCN-amplified NB cells.

Results of an abbreviated phase II study of AKT inhibitor MK-2206 in the treatment of recurrent platinum-resistant high grade serous ovarian, fallopian tube, or primary peritoneal carcinoma (NCT 01283035)

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PI3K/AKT pathway alterations are frequently seen in ovarian cancer, providing rationale for targeted AKT inhibition.

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AKT inhibitor MK-2206 in platinum resistant high grade serous ovarian cancer was notable for dermatologic toxicity.

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Best response of stable disease was seen, with one patient experiencing a prolonged SD of 19 weeks.

Platinum-resistant, recurrent, high grade epithelial ovarian carcinoma remains challenging to treat. Chemotherapy produces limited responses with modest survival benefits in the treatment of recurrent disease. In this context, targeted therapies may improve upon conventional therapies. PI3K/AKT pathway alterations are frequently found in several cancer types, including ovarian cancer, and thus AKT inhibition is a rational targeted therapy. Here we report the results of an abbreviated trial of AKT inhibitor MK-2206 in platinum resistant high grade serous ovarian, fallopian tube, and primary peritoneal cancer with PTEN loss.

Effect of PI3K/Akt Signaling Pathway on PRAS40Thr246 Phosphorylation in Gastric Cancer Cells

BACKGROUND

We aimed to investigate the effect of PI3K/Akt signaling pathway on PRAS40Thr246 phosphorylation in gastric cancer cells.

METHODS

The study was conducted from April 2017 to January 2018 in Zhongshan Hospital, Xiamen University, Xiamen, China. Gastric cancer cells were divided into three groups: gastric cancer cell group, LY294002 group and MK-2206 group. Specific tests were conducted accordingly.

RESULTS

Inhibition of PI3K/Akt signaling pathway activation and PRAS40Thr246 phosphorylation could inhibit proliferation and invasion and promote apoptosis of gastric cancer cells, and PRAS40Thr246 phosphorylation could activate PI3K/Akt signaling pathway.

CONCLUSION

The levels of PI3K/Akt signaling pathway related proteins and p-PRAS40Thr246 were significantly increased in gastric cancer cells. p-PRAS40-Thr246 was able to reflect the activation of the PI3K/Akt signaling pathway, reflecting the sensitivity of the PI3K/AKT signaling pathway to inhibitors.

The Combination of MK-2206 and WZB117 Exerts a Synergistic Cytotoxic Effect Against Breast Cancer Cells

Breast cancer is the most commonly diagnosed cancer and the second leading cause of cancer death in women. Hormone receptor-positive breast cancer is usually subjected to hormone therapy, while triple-negative breast cancer is more formidable and poses a therapeutic challenge. Glucose transporters are potential targets for the development of anticancer drugs. In search of anticancer agents whose effect could be enhanced by a GLUT1 inhibitor WZB117, we found that MK-2206, a potent allosteric Akt inhibitor, when combined with WZB117, showed a synergistic effect on growth inhibition and apoptosis induction in breast cancer cells, including ER(+) MCF-7 cells and triple-negative MDA-MB-231 cells. The combination index values at 50% growth inhibition were 0.45 and 0.21, respectively. Mechanism studies revealed that MK-2206 and WZB117 exert a synergistic cytotoxic effect in both MCF-7 and MDA-MB-231 breast cancer cells by inhibiting Akt phosphorylation and inducing DNA damage. The combination may also compromise DNA damage repair and ultimately lead to apoptosis. Our findings suggest that the combination of Akt inhibitors and GLUT1 inhibitors could be a novel strategy to combat breast cancer.

A phase I trial of MK-2206 and hydroxychloroquine in patients with advanced solid tumors

PURPOSE

Given the evidence that coordinate inhibition of AKT induces autophagy, we studied the combination of the AKT inhibitor, MK-2206 with hydroxychloroquine (HCQ) in patients with advanced solid tumors.

METHODS

Patients were treated with weekly MK-2206 (135 mg or 200 mg) plus HCQ (200 mg, 400 mg or 600 mg BID).

RESULTS

Thirty-five patients were enrolled across 5 dose levels. Two DLTs of grade 3 maculo-papular rash were observed at dose level 2 (MK-2206 200 mg weekly plus HCQ at 400 mg BID) and 1 DLT of grade 3 fatigue at dose level 2B (MK-2206 135 mg weekly plus HCQ 600 mg BID). The maximum tolerated dose (MTD) was declared as dose level 2B. The most common adverse events attributed to MK-2206 were hyperglycemia (N = 18; 51%), fatigue (N = 17; 49%), maculo-papular rash (N = 16; 46%), diarrhea (N = 12; 34%), anorexia (N = 11; 31%), and nausea (N = 11; 31%). Patients experiencing adverse events attributed to HCQ were small in number (N = 13) and primarily included fatigue (N = 5; 14%) and maculo-papular rashes (N = 3; 9%). Statistically significant effects on the pharmacokinetic properties of MK-2206 were observed in combination with HCQ. In addition, the plasma concentrations of HCQ in the combination with MK-2206 were significantly higher than the plasma levels of HCQ as monotherapy in prior studies. The best overall response of stable disease was observed in 5/34 (15%) patients.

CONCLUSION

The combination of MK-2206 and hydroxychloroquine was tolerable, but with substantial number of drug-related AEs and minimal evidence of antitumor activity.

Positive Effects of PI3K/Akt Signaling Inhibition on PTEN and P53 in Prevention of Acute Lymphoblastic Leukemia Tumor Cells

Purpose: The PI3K/Akt signaling pathway regulates cell growth, proliferation and viability in hematopoietic cells. This pathway always dysregulates in acute lymphoblastic leukemia (ALL). PTEN and P53 are tumor suppressor genes correlated with PI3K/Akt signaling pathway, and both have a tight link in regulation of cell proliferation and cell death. In this study, we investigated the effects of dual targeting of PI3K/Akt pathway by combined inhibition with nvp-BKM-120 (PI3K inhibitor) and MK-2206 (Akt inhibitor) in relation with PTEN and P53 on apoptosis and proliferation of leukemia cells.

Methods: Both T and B ALL cell lines were treated with both inhibitors alone or in combination with each other, and induction of apoptosis and inhibition of proliferation were evaluated by flow cytometry. Expression levels of PTEN as well as p53 mRNA and protein were measured by real-time qRT-PCR and western blot, respectively.

Results: We indicated that both inhibitors (BKM-120 and MK-2206) decreased cell viability and increased cytotoxicity in leukemia cells. Reduction in Akt phosphorylation increased PTEN and p53 mRNA and p53 protein level (in PTEN positive versus PTEN negative cell lines). Additionally, both inhibitors, particularly in combination with each other, increased apoptosis (evaluated with Annexin V and caspase 3) and reduced proliferation (Ki67 expression) in leukemia cells. However, administration of IL7 downregulated PTEN and P53 mRNA expression and rescued cancer cells following inhibition of BKM-120 and MK-2206.

Conclusion: This investigation suggested that inhibition of Akt and PI3K could be helpful in leukemia treatment.

Overexpression of steroid receptor coactivators alleviates hyperglycemia-induced endothelial cell injury in rats through activating the PI3K/Akt pathway

Hyperglycemia is a major factor in vascular endothelial injury that finally leads to a cardiovascular event. Steroid receptor coactivators (SRCs) are a group of non-DNA binding proteins that induce structural changes in steroid receptors (nuclear receptors) critical for transcriptional activation. SRCs, namely, SRC-1, SRC-2, and SRC-3, are implicated in the regulation of vascular homeostasis. In this study we investigate the role of SRCs in hyperglycemia-induced endothelial injury. Aortic endothelial cells were prepared from normal and diabetic rats, respectively. Diabetic rats were prepared by injection of streptozotocin (50 mg/kg, i.p.). The expression levels of SRC-1 and SRC-3 were significantly decreased in endothelial cells from the diabetic rats. Similar phenomenon was also observed in aortic endothelial cells from the normal rats treated with a high glucose (25 mM) for 4 h or 8 h. The expression levels of SRC-2 were little affected by hyperglycemia. Overexpression of SRC-1 and SRC-3 in high glucose-treated endothelial cells significantly increased the cell viability, suspended cell senescence, and inhibited cell apoptosis compared with the control cells. We further showed that overexpression of SRC-1 and SRC-3 markedly suppressed endothelial injury through restoring nitric oxide production, upregulating the expression of antioxidant enzymes (SOD, GPX, and CAT), and activating the PI3K/Akt pathway. The beneficial effects of SRC-1 and SRC-3 overexpression were blocked by treatment with the PI3K inhibitor LY294002 (10 mM) or with the Akt inhibitor MK-2206 (100 nM). In conclusion, hyperglycemia decreased SRC-1 and SRC-3 expression levels in rat aortic endothelial cells. SRC-1 and SRC-3 overexpression might protect against endothelial injury via inhibition of oxidative stress and activation of PI3K/Akt pathway.

Inhibition of AKT suppresses the initiation and progression of BRCA1-associated mammary tumors

Despite the high incidence of BRCA1-mutant breast cancer, few substantial improvements in preventing or treating such cancers have been made. Using a Brca1-mutant mouse model, we examined the contribution of AKT to the incidence and growth of Brca1-mutated mammary tumors. A haploinsufficiency of Akt1 in Brca1-mutant mouse model significantly decreased mammary tumor formation from 54% in Brca1co/coMMTV-Cre mice to 22% in Brca1 co/coMMTV-Cre Akt1+/- mice. Notably, treatment of tumor-bearing Brca1-mutant mice with the AKT-inhibitor, MK-2206, yielded partial response or stable disease up to 91% of mice in maximum response. MK-2206 treatment also significantly reduced tumor volume and delayed recurrence in allograft and adjuvant studies, respectively. A correlation analysis of MK-2206 responses with gene expression profiles of tumors at baseline identified seven genes that were differentially expressed between tumors that did and did not respond to MK-2206 treatment. Our findings enhance our understanding of the involvement of AKT signaling in BRCA1-deficient mammary tumors and provide preclinical evidence that targeted AKT inhibition is a potential strategy for the prevention and therapeutic management of BRCA1-associated breast cancer.

AKT inhibitor MK-2206 sensitizes breast cancer cells to MLN4924, a first-in-class NEDD8-activating enzyme (NAE) inhibitor

Breast cancer is a common type of cancer among female cancer patients and the main cause of cancer-related deaths. During the last decades, targeted therapies for breast cancer have been rapidly developing. Among them, MLN4924, a first-in-class NEDD8-activating enzyme (NAE) inhibitor, has performed antitumor activity by inactivating the cullin-RING ligases and causing the accumulation of their substrates to induce apoptosis in a number of studies. In this study, we found that MLN4924 activates the AKT pathway in both HER2-positive and triple-negative breast cancer (TNBC) cell lines. Given that AKT signaling is responsible for tumor progression and drug resistance in some types of cancers, we hypothesized that the AKT inhibitor may synergistically enhance the tumor suppression capability in breast cancer by MLN4924. To demonstrate the sensitizing effect, MK-2206 was chosen as the adjuvant treatment, and cell growth, migration and apoptosis were detected. The results showed that MLN4924 treatment inhibited cell growth and migration and induced apoptosis in both SK-BR3 and MDA-MB231 breast cancer cell lines. More importantly, the combined treatment of MLN4924 and MK-2206 indeed caused stronger cytotoxicity and inhibition of migration and a much higher induction of apoptosis compared with MLN4924 treatment alone. Our study provides the proof-of-concept evidence for strategic drug combination of MLN4924 with an AKT inhibitor for maximal killing of breast cancer cells via the enhancement of apoptosis.

MK-2206, an allosteric inhibitor of AKT, stimulates LDLR expression and LDL uptake: A potential hypocholesterolemic agent

BACKGROUND AND AIMS

Induction of low-density lipoprotein receptor (LDLR) plays a significant role in reduction of plasma LDL-cholesterol (LDL-C) levels. Therefore, strategies that enhance the protein level of LDLR provide an attractive therapeutic target for the treatment of hypercholesterolemia. With this aim in mind, we concentrated our effort on studying the role of AKT kinase in regulation of LDLR levels and proceeded to examine the effect of MK-2206, an allosteric and highly selective AKT inhibitor, on LDLR expression.

METHODS

Cultured human hepatoma cells were used to examine the effect of MK-2206 on the proteolytic processing of sterol regulatory element-binding protein-2 (SREBP-2), the expression of LDLR and cellular internalization of LDL. We also examined the effect of MK-2206 on LDLR levels in primary human hepatocytes.

RESULTS

MK-2206 induced the proteolytic processing of SREBP-2, upregulated LDLR expression and stimulated LDL uptake. In contrast to statins, induction of LDLR levels by MK-2206 did not rely on 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR) inhibition. As a result, cotreatment of cells with MK-2206 and mevastatin potentiated the impact of mevastatin on LDLR. Importantly, MK-2206 stimulated the expression of LDLR by primary human hepatocytes.

CONCLUSIONS

MK-2206 is a novel LDLR-inducing agent that, either alone or in combination with statins, exerts a stimulating effect on cellular LDL uptake.

Pre-surgical trial of the AKT inhibitor MK-2206 in patients with operable invasive breast cancer: a New York Cancer Consortium trial

INTRODUCTION

The PI3K/AKT/mTOR pathway is an oncogenic driver in breast cancer (BC). In this multi-center, pre-surgical study, we evaluated the tissue effects of the AKT inhibitor MK-2206 in women with stage I-III BC.

MATERIALS AND METHODS

Two doses of weekly oral MK2206 were administered at days - 9 and - 2 before surgery. The primary endpoint was reduction of pAkt^Ser473 in breast tumor tissue from diagnostic biopsy to surgery. Secondary endpoints included changes in PI3K/AKT pathway tumor markers, tumor proliferation (ki-67), insulin growth factor pathway blood markers, pharmacokinetics (PK), genomics, and MK-2206 tolerability. Paired t tests were used to compare biomarker changes in pre- and post-MK-2206, and two-sample t tests to compare with prospectively accrued untreated controls.

RESULTS

Despite dose reductions, the trial was discontinued after 12 patients due to grade III rash, mucositis, and pruritus. While there was a trend to reduction in pAKT after MK-2206 (p = 0.06), there was no significant change compared to controls (n = 5, p = 0.65). After MK-2206, no significant changes in ki-67, pS6, PTEN, or stathmin were observed. There was no significant association between dose level and PK (p = 0.11). Compared to controls, MK-2206 significantly increased serum glucose (p = 0.02), insulin (p < 0.01), C-peptide (p < 0.01), and a trend in IGFBP-3 (p = 0.06).

CONCLUSION

While a trend to pAKT reduction after MK-2206 was observed, there was no significant change compared to controls. However, the accrued population was limited, due to toxicity being greater than expected. Pre-surgical trials can identify in vivo activity in the early drug development, but side effects must be considered in this healthy population.

1,25-OH2 vitamin D3 and AKT-inhibition increase glucocorticoid induced apoptosis in a model of T-cell acute lymphoblastic leukemia (ALL)

In acute lymphoblastic leukemia (ALL), steroid resistance and hypovitaminosis D are both associated with a poor prognosis. We show that methylprednisolone, calcitriol and the AKT-inhibitor MK-2206 have a synergistic effect on the apoptosis of steroid resistant T-ALL cells. Compared to methylprednisolone monotherapy, calcitriol increases methylprednisolone induced apoptosis dose-dependently (1.37-1.92-fold; p < 0.05). Pre-incubation with calcitriol increases the apoptotic effect of MK-2206 even further (3.6-fold; p < 0.05). It also potentiates synergism between MK-2206 and methylprednisolone (vehicle control 38% vs. calcitriol 58%, p < 0.01). The combination of calcitriol and AKT inhibition should be investigated further as treatment options for steroid resistance in T-ALL.

Combined inhibition of AKT and HSF1 suppresses breast cancer stem cells and tumor growth

Breast cancer is the most common cancer in women and the second leading cause of cancer deaths in women. Over 90% of breast cancer deaths are attributable to metastasis. Our lab has recently reported that AKT activates heat shock factor 1 (HSF1), leading to epithelial-to-mesenchymal transition in HER2-positive breast cancer. However, it is unknown whether the AKT-HSF1 pathway plays an important role in other breast cancer subtypes, breast cancer stem cells, or breast cancer growth and metastasis. Herein, we showed AKT and HSF1 to be frequently co-activated in breast cancer cell lines and specimens across different subtypes. Activated AKT (S473) and HSF1 (S326) are strongly associated with shortened time to metastasis. Inhibition of the AKT-HSF1 signaling axis using small molecule inhibitors, HSF1 knockdown or the dominant-negative HSF1 mutant (S326A) reduced the growth of metastatic breast cancer cells and breast cancer stem cells. The combination of small molecule inhibitors targeting AKT (MK-2206) and HSF1 (KRIBB11) resulted in synergistic killing of breast cancer cells and breast cancer stem cells across different molecular subtypes. Using an orthotopic xenograft mouse model, we found that combined targeting of AKT and HSF1 to significantly reduce tumor growth, induce tumor apoptosis, delay time to metastasis, and prolong host survival. Taken together, our results indicate AKT-HSF1 signaling mediates breast cancer stem cells self-renewal, tumor growth and metastasis, and that dual targeting of AKT and HSF1 resulted in synergistic suppression of breast cancer progression thereby supporting future testing of AKT-HSF1 combination therapy for breast cancer patients.

A randomized phase 2 study of MK-2206 versus everolimus in refractory renal cell carcinoma

Background

Activation of the phosphoinisitide-3 kinase (PI3K) pathway through mutation and constitutive upregulation has been described in renal cell carcinoma (RCC), making it an attractive target for therapeutic intervention. We performed a randomized phase II study in vascular endothelial growth factor (VEGF) therapy refractory patients to determine whether MK-2206, an allosteric inhibitor of AKT, was more efficacious than the mammalian target of rapamycin inhibitor everolimus.

Patients and methods

A total of 43 patients were randomized in a 2:1 distribution, with 29 patients assigned to the MK-2206 arm and 14 to the everolimus arm. Progression-free survival (PFS) was the primary endpoint.

Results

The trial was closed at the first futility analysis with an observed PFS of 3.68 months in the MK-2206 arm and 5.98 months in the everolimus arm. Dichotomous response rate profiles were seen in the MK-2206 arm with one complete response and three partial responses in the MK-2206 arm versus none in the everolimus arm. On the other hand, progressive disease was best response in 44.8% of MK2206 versus 14.3% of everolimus-treated patients. MK-2206 induced significantly more rash and pruritis than everolimus, and dose reduction occurred in 37.9% of MK-2206 versus 21.4% of everolimus-treated patients. Genomic analysis revealed that 57.1% of the patients in the PD group had either deleterious TP53 mutations or ATM mutations or deletions. In contrast, none of the patients in the non-PD group had TP53 or ATM defects. No predictive marker for response was observed in this small dataset.

Conclusions

Dichotomous outcomes are observed when VEGF therapy refractory patients are treated with MK-2206, and MK-2206 does not demonstrate superiority to everolimus. Additionally, mutations in DNA repair genes are associated with early disease progression, indicating that dysregulation of DNA repair is associated with a more aggressive tumor phenotype in RCC.

Combined Targeting of mTOR and Akt Using Rapamycin and MK-2206 in The Treatment of Tuberous Sclerosis Complex

Tuberous sclerosis complex (TSC), caused by loss-of-function mutations in the TSC1 or TSC2 genes, is an autosomal dominant disease characterized by benign tumor formation in multiple organs. Hyperactivation of mammalian target of rapamycin (mTOR) is the primary alteration underlying TSC tumor. Thus, rapamycin, as an mTOR specific inhibitor, has been assumed as a potential drug for the treatment of TSC. However, its application in TSC patients has been limited due to side effects. By analyzing Tsc1- or Tsc2-null mouse embryonic fibroblasts (MEFs), we found that loss of TSC1 or TSC2 led to a decreased sensitivity to MK-2206, a novel allosteric Akt inhibitor. Ectopic expression of a constitutively activated Akt (myristoylated Akt-1, myrAkt-1) sensitized Tsc2-null and Tsc1-null MEFs to MK-2206. Furthermore, MK-2206 increased the cytotoxicity of rapamycin in Tsc1^-/- or Tsc2^-/- MEFs. Moreover, the benefit of the combinatorial treatment was also demonstrated in a TSC xenograft mouse model. We conclude that the combination of rapamycin and MK-2206 may be utilized as a new therapeutic regimen for TSC.

Co-treatment of LY294002 or MK-2206 with AZD5363 Attenuates AZD5363-induced Increase in the Level of Phosphorylated AKT

Clinical trials are in progress on AZD5363, an inhibitor of protein kinase B (AKT), to assess its effects on the phosphoinositide 3-kinase (PI3K)/AKT/mammalian target of rapamycin (mTOR) pathway. Cells treated with AKT inhibitors have been reported to activate alternative pathways in order to escape growth inhibition. AZD5363-sensitized Hs578T breast cancer cells displayed reduced levels of phosphorylated glycogen synthase kinase 3 beta (pGSK3β). Interestingly, in AZD5363-treated cells, the level of phosphorylated (activated) AKT (pAKT) increased. Since pAKT positively correlates with cancer growth and survival, we aimed to identify conditions that could reduce AZD5363-induction of pAKT. We examined whether AZD5363 induction of pAKT could be reduced by co-treatment with inhibitors of the PI3K/AKT/mTOR pathway (LY294002, MK-2206, wortmannin, perifosine, rapamycin, everolimus, and temsirolimus). We observed that co-treatment of LY294002 or MK-2206 with AZD5363 reduced the level of pAKT. Since MK-2206 is clinically used, we propose that co-treatment using MK-2206 with AZD5363 would prove beneficial in blocking the AZD5363-induced pAKT signaling pathway. Our findings contribute to the development of AZD5363-based sensitization therapies for patients with cancer.

Recurrent AKT mutations in human cancers: functional consequences and effects on drug sensitivity

Precision oncology trials based on tumor gene sequencing depend on robust knowledge about the phenotypic consequences of the genetic variants identified in patients' tumors. Mutations in AKT1-3 occur in 3-5% of human cancers. Although a single hotspot mutation, E17K, is the most common, well characterized activating mutations account for a minority of Akt variants that have been identified in large tumor sequencing studies to date. In order to determine the potential clinical relevance of both common and rare Akt mutations, we expressed a set of over twenty recurrent Akt mutants in three different cell lines and evaluated activation of Akt pathway signaling and effects on growth. We determined their relative sensitivity to allosteric and ATP-competitive Akt inhibitors in clinical development. Most Akt mutants did not activate pathway signaling compared to wild type Akt and did not affect growth properties. In addition, the most common activating Akt mutations, including Akt1 E17K, L52R, and Q79K conferred neither sensitivity nor resistance to Akt inhibitors. Equivocal evidence was found that Akt1 D323H and Akt2 W80C mutants are relatively resistant to the allosteric Akt inhibitor MK-2206, but not an ATP-competitive inhibitor. Our results suggest that the vast majority of rare Akt variants are passenger mutations with no effect on drug sensitivity. The hypothesis that activating Akt mutations predict for Akt inhibitor sensitivity remains to be tested clinically, but is not yet supported by our preclinical data.

MK-2206 sensitizes BRCA-deficient epithelial ovarian adenocarcinoma to cisplatin and olaparib

BACKGROUND

Platinum resistance is a major obstacle in the treatment of epithelial ovarian cancer (EOC). Activation of the AKT pathway promotes platinum resistance while inhibition of AKT sensitizes chemoresistant cells. Patients with BRCA mutant EOC, and thus a defect in the homologous recombination (HR) repair pathway, demonstrate greater clinical response to platinum and olaparib therapy than patients with BRCA wild-type EOC. MK-2206, an allosteric inhibitor of AKT phosphorylation, sensitizes a variety of cell types to various anticancer agents and is currently undergoing phase II trials as monotherapy for platinum-resistant ovarian, fallopian tube, and peritoneal cancer. This study examines the differential effects of AKT inhibition with cisplatin and olaparib therapy in BRCA1/2-deficient versus wild-type EOC.

METHODS

PEO1, a chemosensitive BRCA2-mutant serous ovarian adenocarcinoma, and PEO4, a reverted BRCA2-proficient line from the same patient after the development of chemotherapeutic resistance, were primarily used for the study. In PEO1, MK-2206 demonstrated moderate to strong synergism with cisplatin and olaparib at all doses, while demonstrating antagonism at all doses in PEO4.

RESULTS

Baseline phospho-AKT activity in untreated cells was upregulated in both BRCA1- and 2-deficient cell lines. MK-2206 prevented cisplatin- and olaparib-induced AKT activation in the BRCA2-deficient PEO1 cells. We propose that BRCA-deficient EOC cells upregulate baseline AKT activity to enhance survival in the absence of HR. Higher AKT activity is also required to withstand cytotoxic agent-induced DNA damage, leading to strong synergism between MK-2206 and cisplatin or olaparib therapy in BRCA-deficient cells.

CONCLUSIONS

MK-2206 shows promise as a chemosensitization agent in BRCA-deficient EOC and merits clinical investigation in this patient population.

MK-2206 co-treatment with 5-fluorouracil or doxorubicin enhances chemosensitivity and apoptosis in gastric cancer by attenuation of Akt phosphorylation

The anticancer effect of MK-2206, an Akt inhibitor, has been explored in some types of cancers, but its effect on gastric cancer is unclear. In this study, we aimed to investigate its anticancer effect in gastric cancer cells. Cell viability and colony formation assays showed that MK-2206 effectively inhibited the proliferation of SGC-7901 and MKN45 cells. The 50% inhibitory concentration values after 24, 48, and 72 hours' treatment were 22.92, 13.68, and 8.55 μM in SGC-7901 cells and 19.21, 13.10, and 9.11 μM in MKN45 cells, respectively. Treatment with MK-2206 induced apoptosis in SGC-7901 cells as indicated by flow cytometry assay. The combination indexes of MK-2206 and doxorubicin were 0.59 in SGC-7901 cells and 0.57 in MKN45 cells, whereas for 5-fluorouracil (5-FU) the indexes were 0.17 in SGC-7901 cells and 0.73 in MKN45 cells, indicating that MK-2206 could work synergistically with doxorubicin or 5-FU to inhibit cell growth. Furthermore, a small dose (1 μM) of MK-2206 co-treatment with doxorubicin or 5-FU was sufficient for complete inhibition of chemotherapeutic alteration of phosphorylated Akt expression and significant enhancement of pro-apoptosis effect through the activation of caspase pathway. Therefore, MK-2206 effectively inhibits gastric cancer cell growth by attenuation of Akt phosphorylation and synergistically enhances the antitumor effect of doxorubicin and 5-FU via caspase-dependent apoptosis.

A phase 1b study of the Akt-inhibitor MK-2206 in combination with weekly paclitaxel and trastuzumab in patients with advanced HER2-amplified solid tumor malignancies

PURPOSE

Akt plays a key role in the aggressive pathogenesis of HER2+ malignancies, suggesting that Akt-inhibitors may be of therapeutic value in the treatment of HER2+ tumors. Preclinical studies demonstrate synergy between MK-2206, a selective allosteric Akt-inhibitor, with paclitaxel and trastuzumab. We aimed to evaluate the safety of this combination in patients with HER2+ malignancies.

METHODS

We conducted a phase 1b study of weekly MK-2206 in combination with weekly paclitaxel 80 mg/m(2) and trastuzumab 2 mg/kg in patients with HER2+ malignancies. Dose escalation was performed using a modified toxicity probability interval method. Molecular profiling of archived tissue samples and limited PK analyses were performed.

RESULTS

16 patients with HER2+ tumors were enrolled (12 breast, 3 gastric, 1 esophageal). 81 and 75 % had received prior trastuzumab and taxane chemotherapy, respectively. MK-2206 135 mg/week was determined to be tolerable. Three dose-limiting toxicities were observed including two grade 3 rashes and 1 grade 3 neutropenia resulting in a > 7 day delay in treatment. Grade 3/4 adverse events include neutropenia (44 %), rash (13 %), peripheral neuropathy (6 %), and depression (6 %). 10 patients (63 %) demonstrated tumor response (3 complete, 7 partial). Median duration of response was 6 months. Exploratory analyses identified STARD3, TM7SF2, and G3BP1 as potential biomarkers of response.

CONCLUSIONS

MK-2206 at a dose of 135 mg/week in combination with weekly paclitaxel and trastuzumab is safe and well tolerated, and is the recommended phase 2 dose for this combination. Preliminary data indicate significant clinical activity in patients with HER2+ tumors despite prior HER2-directed therapy.

Akt inhibitor MK-2206 enhances the effect of cisplatin in gastric cancer cells

The phosphoinositide 3-kinase/Akt pathway activation commonly occurs in various types of human cancer and has an important role in chemoresistance. Combination of traditional chemotherapy drugs and molecular-targeted agents is a promising strategy for cancer therapy, which has shown enhanced cytotoxicity and lower drug resistance. The present study found that the Akt inhibitor, MK-2206, can increase the effect of cisplatin in the gastric cancer cell line AGS, which has higher Akt phosphorylation, but exhibited a poor combination effect in MKN-45 and MGC-803 cells, which have limited Akt activation. The MTT assay demonstrated that sequential treatment of cisplatin, followed by the Akt inhibitor, MK-2206, caused a synergistic effect of proliferation inhibition, and the apoptosis assay by propidium iodide/fluorescein isothiocyanate staining also showed that combination treatment induced more apoptosis compared to the monotherapy groups. Using western blot analysis, MK-2206 was shown to significantly suppress the phosphorylation of Akt (Ser473), however, the expression of total Akt remained the same, and the combination treatment also increased the expression of cleaved poly adenosine diphosphate ribose polymerase, which contributed to apoptosis.

Triple Akt inhibition as a new therapeutic strategy in T-cell acute lymphoblastic leukemia

T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive neoplastic disorder in which chemotherapy resistance and refractory relapses occur, with a poorer prognostic outcome.

Constitutively active PI3K/Akt/mTOR pathway is a common feature of T-ALL upregulating cell proliferation, survival and drug resistance. This pathway is currently under clinical trials with small molecules inhibitors (SMI).

To verify whether a multi-inhibition treatment against Akt protein could enhance the efficacy of individual drug administration and overcome drug resistance as well as to obtain a decrease in single drug concentration, we tested on T-ALL cell lines the effects of combined treatments with three Akt inhibitors with different mode of action, GSK690693, MK-2206 and Perifosine.

In cells with hyperactivated Akt, combined administration of the drugs displayed a significant synergistic and cytotoxic effect and affected PI3K/Akt/mTOR pathway at much lower concentration than single drug use. Highest synergistic effect for full inhibition of Akt was also related to the timing of every drug administration. Furthermore the triple treatment had greater efficacy in inducing cell cycle arrest in G₀/G₁ phase and both apoptosis and autophagy.

Targeting Akt as a key protein of PI3K/Akt/mTOR pathway with multiple drugs might represent a new and promising pharmacological strategy for treatment of T-ALL patients.

Phase 2 study of MK-2206, an allosteric inhibitor of AKT, as second-line therapy for advanced gastric and gastroesophageal junction cancer: A SWOG cooperative group trial (S1005)

BACKGROUND

The AKT inhibitor MK-2206 at a dose of 60 mg every other day was evaluated in gastric/gastroesophageal junction cancers.

METHODS

Patients who had progressed after first-line treatment were eligible. Pertinent eligibility criteria included adequate organ function, a fasting serum glucose level ≤ 150 mg/dL, and less than grade 2 malabsorption or chronic diarrhea. MK-2206 was given orally (60 evaluable patients required). The primary endpoint was overall survival, and a median survival of 6.5 months (power, 89%; significance level, 0.07) was considered encouraging for further investigation.

RESULTS

Seventy patients were included in the final analyses. The median age was 59.8 years (range, 30.4-86.7 years); 70% were male, 89% were white, and 7% were Asian. There were 2 deaths possibly related to the study drug (cardiac arrest and respiratory failure). Grade 4 adverse events included hyperglycemia, anemia, and lung infection (1 each). Grade 3 adverse events occurred in < 5% of patients except for fatigue (6%). Other adverse events (all grades) included anemia (17%), anorexia (30%), diarrhea (26%), fatigue (50%), hyperglycemia (30%), nausea (40%), vomiting (22%), dry skin (19%), maculopapular rash (30%), and acneiform rash (13%). The response rate was 1%, the median progression-free survival was 1.8 months (95% confidence interval, 1.7-1.8 months), and the median overall survival was 5.1 months (95% confidence interval, 3.7-9.4 months)

CONCLUSIONS

MK-2206 as second-line therapy was well tolerated by an unselected group of patients with gastric/gastroesophageal junction cancers, but it did not have sufficient activity (response rate, 1%; overall survival, 5.1 months) to warrant further testing in this population.

Development of a new model system to dissect isoform specific Akt signalling in adipocytes

Our study describes the development and validation of a new model system that allows for acute control of signalling by specific Akt isoforms. This model system revealed new insights into the role of Akt kinases in glucose transport and adipogenesis.

Protein kinase B (Akt) kinases are critical signal transducers mediating insulin action. Genetic studies revealed that Akt1 and Akt2 signalling differentially contribute to sustain lipid and glucose homoeostasis; however Akt isoform-specific effectors remain elusive due to the lack of a suitable model system to mechanistically interrogate Akt isoform-specific signalling. To overcome those technical limitations we developed a novel model system that provides acute and specific control of signalling by Akt isoforms. We generated mutants of Akt1 and Akt2 resistant to the allosteric Akt inhibitor MK-2206. We then developed adipocyte cell lines, in which endogenous Akt1 or Akt2 has been replaced by their corresponding drug-resistant Akt mutant. Treatment of those cells with MK-2206 allowed for acute and specific control of either Akt1 or Akt2 function. Our data showed that Akt1^W80A and Akt2^W80A mutants are resistant to MK-2206, dynamically regulated by insulin and able to signal to Akt downstream effectors. Analyses of insulin action in this cellular system showed that Akt1 and Akt2 are both able to mediate insulin regulation of the transcription factor forkhead box O1 (FoxO1) and the glucose transporter 4 (GLUT4), revealing a redundant role for these Akt kinases in the control of glucose transport into fat cells. In contrast, Akt1 signalling is uniquely required for adipogenesis, by controlling the mitotic clonal expansion (MCE) of pre-adipocytes that precedes white adipose cell differentiation. Our data provide new insights into the role of Akt kinases in glucose transport and adipogenesis and support our model system as a valuable tool for the biochemical characterization of signalling by specific Akt isoforms.

Effects of an oral allosteric AKT inhibitor (MK-2206) on human nasopharyngeal cancer in vitro and in vivo

Aim

Protein kinase B (AKT) signaling frequently is deregulated in human cancers and plays an important role in nasopharyngeal carcinoma (NPC). This preclinical study investigated the effect of MK-2206, a potent allosteric AKT inhibitor, on human NPC cells in vitro and in vivo.

Methods

The effect of MK-2206 on the growth and proliferation of CNE-1, CNE-2, HONE-1, and SUNE-1 cells was assessed by Cell Counting Kit 8 and colony formation assay. Flow cytometry was performed to analyze cell cycle and apoptosis. The effects of MK-2206 on the AKT pathway were analyzed by Western blotting. Autophagy induction was evaluated via electron microscopy and Western blot. To test the effects of MK-2206 in vivo, CNE-2 cells were subcutaneously implanted into nude mice. Tumor-bearing mice were treated orally with MK-2206 or placebo. Tumors were harvested for immunohistochemical analysis.

Results

In vitro, MK-2206 inhibited the four NPC cell line growths and reduced the sizes of the colonies in a dose-dependent manner. At 72 and 96 hours, the half maximal inhibitory concentration (IC₅₀) values of MK-2206 in CNE-1, CNE-2, and HONE-1 cell lines were 3–5 μM, whereas in SUNE-1, IC₅₀ was less than 1 μM, and MK-2206 induced cell cycle arrest at the G1 phase. However, our study found no evidence of apoptosis. MK-2206 induced autophagy in NPC cells, as evidenced by electron microscopy and Western blot, and inhibited the growth of tumors that were subcutaneously implanted in mice. Inhibition of downstream phosphorylation through the PRAS40 and S6 pathways seems to be the main mechanism for the MK-2206-induced growth inhibition.

Conclusion

Our preclinical study suggests that MK-2206’s antiproliferative effect may be useful for NPC treatment; however, strategies for reinforcing this effect are needed to maximize clinical benefit.

A phase I trial of MK-2206 in children with refractory malignancies: a Children's Oncology Group study

BACKGROUND

We report results of a phase I trial designed to estimate the maximum tolerated dose (MTD), describe dose-limiting toxicities (DLT), and characterize the pharmacokinetic profile of MK-2206, an AKT inhibitor, in children with refractory or recurrent malignancies.

PROCEDURE

MK-2206 was administered either every other day (Schedule 1), or once a week (Schedule 2) in a 28-day cycle. Dose escalations in increments of ∼30% were independently made in each part using the rolling-six design. Serial pharmacokinetic (PK) studies were obtained. Biological studies include analysis of PI3K/PTEN/AKT-cell signaling pathway in pre and post-therapy in PBMC and in tumors at diagnosis or recurrence.

RESULTS

Fifty patients (26 males, median age 12.6 years [range, 3.1-21.9]) with malignant glioma (16), ependymoma (4), hepatocellular carcinoma (3), gliomatosis cereberi (2), or other tumors (22) were enrolled; 40 were fully evaluable for toxicity (Schedule 1, n = 23; Schedule 2, n = 17). Schedule 1 DLTs included: grade 3 dehydration in 1/6 patients at 28 mg/m(2) ; grade 4 hyperglycemia and neutropenia in 1/6 patients at 45 mg/m(2) ; and grade 3 rash in 3/6 patients at dose level 4 (58 mg/m(2) ). Schedule 2 DLTs included: grade 3 alkaline phosphatase in 1/6 patients at 90 mg/m(2) ; grade 3 rash in 1/6 patients at 120 mg/m(2) ; and grade 3 rash in 2/6 patients at 155 mg/m(2) .

CONCLUSIONS

The recommended pediatric phase 2 dose of MK-2206 is 45 mg/m(2) /dose every other day or 120 mg/m(2) /dose weekly. PK appeared linear over the dose range studied.

AKT as a therapeutic target in multiple myeloma

INTRODUCTION

Multiple myeloma remains an incurable malignancy with poor survival. Novel therapeutic approaches capable of improving outcomes in patients with multiple myeloma are urgently required. AKT is a central node in the phosphatidylinositol-3-kinase/AKT/mammalian target of rapamycin signaling pathway with high expression in advanced and resistant multiple myeloma. AKT contributes to multiple oncogenic functions in multiple myeloma which may be exploited therapeutically. Promising preclinical data has lent support for pursuing further development of AKT inhibitors in multiple myeloma. Lead drugs are now entering the clinic.

AREAS COVERED

The rationale for AKT inhibition in multiple myeloma, pharmacological subtypes of AKT inhibitors in development, available results of clinical studies of AKT inhibitors and suitable drug partners for further development in combination with AKT inhibition in multiple myeloma are discussed.

EXPERT OPINION

AKT inhibitors are a welcome addition to the armamentarium against multiple myeloma and promising clinical activity is being reported from ongoing trials in combination with established and/or novel treatment approaches. AKT inhibitors may be set to improve patient outcomes when used in combination with synergistic drug partners.

Targeting AKT with the allosteric AKT inhibitor MK-2206 in non-small cell lung cancer cells with acquired resistance to cetuximab

The epidermal growth factor receptor (EGFR) is a central regulator of tumor progression in human cancers. Cetuximab is an anti-EGFR monoclonal antibody that has been approved for use in oncology. Despite clinical success the majority of patients do not respond to cetuximab and those who initially respond frequently acquire resistance. To understand how tumor cells acquire resistance to cetuximab we developed a model of resistance using the non-small cell lung cancer line NCI-H226. We found that cetuximab-resistant (Ctx (R) ) clones manifested strong activation of EGFR, PI3K/AKT and MAPK. To investigate the role of AKT signaling in cetuximab resistance we analyzed the activation of the AKT pathway effector molecules using a human AKT phospho-antibody array. Strong activation was observed in Ctx (R) clones for several key AKT substrates including c-jun, GSK3β, eIF4E, rpS6, IKKα, IRS-1 and Raf1. Inhibition of AKT signaling by siAKT1/2 or by the allosteric AKT inhibitor MK-2206 resulted in robust inhibition of cell proliferation in all Ctx (R) clones. Moreover, the combinational treatment of cetuximab and MK-2206 resulted in further decreases in proliferation than either drug alone. This combinatorial treatment resulted in decreased activity of both AKT and MAPK thus highlighting the importance of simultaneous pathway inhibition to maximally affect the growth of Ctx (R) cells. Collectively, our findings demonstrate that AKT activation is an important pathway in acquired resistance to cetuximab and suggests that combinatorial therapy directed at both the AKT and EGFR/MAPK pathways may be beneficial in this setting.

Combined targeting of AKT and mTOR using MK-2206 and RAD001 is synergistic in the treatment of cholangiocarcinoma

Cholangiocarcinoma (CCA) is a rare, but devastating disease arising from the epithelium of intrahepatic and extrahepatic bile ducts. There are neither effective systemic therapies nor satisfying treatment options for inoperable CCA. Histopathological and biochemical studies of CCA show frequent dysregulation of the phosphatidylinositol 3-kinase/AKT/mammalian target of rapamycin (mTOR) pathway. Therefore, we investigated the efficacy of the mTOR inhibitor RAD001 and the impact of AKT signaling following mTOR inhibition in the treatment of CCA. RAD001 significantly inhibits proliferation of CCA cell lines, however, a concentration-dependent and isoform specific feedback activation of the three AKT isoforms (AKT1, AKT2 and AKT3) was observed after mTOR inhibition. As activation of AKT might limit the RAD001-mediated anti-tumor effect, the efficacy of combined mTOR and AKT inhibition was investigated using the allosteric AKT inhibitor MK-2206. Our results show that inhibition of AKT potentiates the efficacy of mTOR inhibition both in vitro and in a xenograft mouse model in vivo. Mechanistically, the antiproliferative effect of the pan-AKT inhibitor MK2206 in the CCA cell line TFK-1 was due to inhibition of AKT1 and AKT2, because knockdown of either AKT1 or AKT2, but not AKT3, showed a synergistic reduction of cell proliferation in combination with mTOR treatment. Finally, using an AKT isoform specific in vitro kinase assay, enzymatic activity of each of the three AKT isoforms was detected in all tissue samples from CCA patients, analyzed. In summary, our preclinical data suggest that combined targeting of mTOR and AKT using RAD001 and MK-2206 might be a new, effective strategy for the treatment of CCA.

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.

Akt2 and acid ceramidase cooperate to induce cell invasion and resistance to apoptosis

Both Akt 2 and acid ceramidase (ASAH1) are found aberrantly overexpressed in cancer cells, but whether these two enzymes cooperate to induce malignant transformation is not known. We found that in immortalized, non-transformed cells, ectopic co-expression of Akt2 and ASAH1 is significantly more effective than expression of each gene alone at inducing cell invasion and at conferring resistance to apoptosis. Consistent with these observations, siRNA-mediated depletion of both Akt2 and ASAH1 is much more potent than depleting each alone at inhibiting cell viability/proliferation and cell invasion. Furthermore, pharmacological inhibitors of Akt (TCN or MK-2206) and ASAH1 (B13) synergize to inhibit cell viability/proliferation, and combinations of these drugs are more effective than single-agent treatments at inhibiting cell invasion. Taken together, the results suggest that these two enzymes cooperate to induce malignant transformation and warrant further preclinical studies to evaluate the potential of combining inhibitors of Akt and ASAH1 to treat cancer.