The allosteric AKT inhibitor, MK2206, decreases tumor growth and invasion in patient derived xenografts of endometrial cancer

Murine Xenograft Models as Preclinical Tools in Endometrial Cancer Research

Murine xenograft models are valuable and increasingly used preclinical tools in cancer research to understand disease pathogenesis and guide treatment options. The aim of this narrative review is to summarize the studies that employed mouse xenograft models, using cell lines, patient-derived tumors, or organoids, in endometrial cancer (EC) research, detailing their methodology and main findings. We identified 27 articles reporting on heterotopic EC xenografts, including subcutaneous, subrenal capsule, intraperitoneal, and retro-orbital models, and 18 articles using orthotopic xenografts. Subcutaneous xenografts generated using either cell lines or patient tumors have been widely used; however, their low engraftment rates and the inability to recapitulate main clinical features such as metastases limit their translational value. Subrenal capsule models showed improved engraftment rates compared to subcutaneous models, but tumors exhibited slower and constrained tumor growth. Orthotopic models are technically more challenging to generate and monitor, but tumor growth occurs in a relevant microenvironment and EC ortho-xenografts exhibit high engraftment rates and metastases to clinically relevant sites. Cell line-based xenograft (CDX) models are attractive tools because they are convenient, easy to use, and amenable to genetic modifications, making them suitable for proof-of-concept approaches and large-scale studies. EC xenografts developed from patient tumors (PDTXs) are more labor/cost-intensive for their establishment but can capture the genetic and molecular heterogeneity within and across histologic subtypes and can inform personalized patient treatment. EC organoid-based xenograft (PDOX) models combine the advantages of both CDXs and PDTXs since they are more time- and cost-effective, faithfully maintain tumor characteristics and therapeutic responses, and can be genetically modified. Despite substantial progress in EC management, there are still several unmet needs. Efficient targeted treatments are currently indicated only for a small subgroup of patients, while women with recurrent or advanced-stage EC have very few therapeutic options and their prognosis remains unfavorable. Novel (targeted) drugs, combinational regimens and tools to predict the real drug response in patients are urgently needed. Xenograft models are expected to inform about disease mechanisms and to help identify novel therapeutic options and suitable target patients.

Downregulation of TRIB3 enhances the sensitivity of lung cancer cells to amino acid deprivation by suppressing AKT activation

Tribbles pseudokinase 3 (TRIB3), a member of the mammalian Tribbles family, is implicated in multiple biological processes. This study aimed to investigate the biological functions of TRIB3 in lung cancer and its effect on amino acid-deprived lung cancer cells. TRIB3 mRNA expression was elevated in lung cancer tissues and cell lines compared to normal lung tissues and cells. TRIB3 knockdown markedly reduced the viability and proliferation of H1299 lung cancer cells. Deprivation of amino acids, particularly arginine, glutamine, lysine, or methionine, strongly increased TRIB3 expression via ATF4 activation in H1299 lung cancer cells. Knockdown of TRIB3 led to transcriptional downregulation of ATF4 and reduced AKT activation induced by amino acid deprivation, ultimately increasing the sensitivity of H1299 lung cancer cells to amino acid deprivation. Additionally, TRIB3 knockdown enhanced the sensitivity of H1299 cells to V-9302, a competitive antagonist of transmembrane glutamine flux. These results suggest that TRIB3 is a pro-survival regulator of cell viability in amino acid-deficient tumor microenvironments and a promising therapeutic target for lung cancer treatment.

Ipatasertib, an oral AKT inhibitor, in combination with carboplatin exhibits anti-proliferative effects in uterine serous carcinoma

PURPOSE

Uterine serous carcinoma (USC) exhibits worse survival rates compared to the endometrioid subtype, and there is currently no effective treatment options for recurrence of this disease after platinum-based chemotherapy. Activation of PIK3CA/AKT/mTOR signaling pathway is a common biological feature in USC.

MATERIALS AND METHODS

Ipatasertib (IPAT) is an investigational, orally administered, ATP-competitive, highly selective inhibitor of pan AKT that has demonstrated anti-proliferative activity in a variety of tumor cells and tumor models. In this study, we used IPAT, carboplatin and their combination to investigate the anti-tumor activity in SPEC-2 and ARK-1 cells.

RESULTS

Our results indicate that IPAT combined with carboplatin at low doses was more effective at reducing proliferation, inducing apoptosis and causing cellular stress than IPAT or carboplatin alone. In particular, inhibition of the PIK3CA/AKT/mTOR pathway and induction of DNA damage were involved in the synergistic inhibition by combination treatment of cell viability in USC cells treated with the combination. Furthermore, IPAT in combination with carboplatin significantly reduced cell adhesion and inhibited cell invasion.

CONCLUSIONS

These findings suggest that the combination of IPAT and carboplatin has potential clinical implications for developing new USC treatment strategies.

The Synergistic Anti-colon Cancer Effect of Aurora A Inhibitors and AKT Inhibitors Through PI3K/AKT Pathway

BACKGROUND

Both AKT and Aurora inhibitors are a potential therapeutic agent for the treatment of malignant tumors. However, the role of combined inhibition of AKT and Aurora in colon cancer and its underlying mechanism have yet to be fully investigated.

OBJECTIVE

To investigate the role of combined AKT and Aurora inhibitors in colon cancer and its underlying mechanisms.

METHODS

CCK8 assay, colony formation assay, and flow cytometry were performed to analyze the proliferation and apoptosis of colon cancer cell line SW480 treated with combined AKT inhibitor MK2206 and Aurora inhibitor Alisertib, respectively. And tumor formation and growth were measured in tumor allograft model mice administered with the combined inhibitors. Western blot analysis was used to examine the expression levels of apoptosis-related proteins and signal transduction pathway components. The PI3K agonist 740Y-P and Overexpression of AKT are used to verify whether the PI3K/AKT pathway plays an anti-tumor effect when combined with inhibitory administration.

RESULTS

Aurora A inhibitor Alisertib and AKT inhibitor MK2206 displayed consistent and synergistic antiproliferation and proapoptotic effects. Combined inhibition of Aurora A and AKT down-regulated the expression of Bcl-2/Bax and up-regulated the expression of cleaved-caspase-3 and cleaved-PARP. While single-drug treatment can significantly inhibit the expression of P-PI3K and P-AKT as well as increase the expression of P53 and H2A.X, the combined drugs had a more significant inhibitory effect than the single drug. Moreover, administration of PI3K agonist 740Y-P and AKT1 overexpression in experiments proved that the combined drugs exert an anticancer effect by inhibiting the PI3K/AKT pathway. Meanwhile, we showed that the combined administration had an anti-colon cancer effect on tumor allograft mice, and the underlying mechanism involved inhibition of the PI3K/AKT pathway.

CONCLUSION

Combined administration of Aurora A inhibitor Alisertib and AKT inhibitor MK2206 can inhibit the proliferation of colon cancer cells and induce apoptosis, while inhibiting tumor growth in vivo. The underlying mechanism may involve the PI3K/AKT pathway and DNA damage pathway.

Utilizing an Endogenous Progesterone Receptor Reporter Gene for Drug Screening and Mechanistic Study in Endometrial Cancer

Expression of progesterone receptor (PR) is a favorable prognostic marker for multiple solid tumors. However, PR expression is reduced or lost in malignant tumors. Thus, monitoring and restoring functional PR expression is important in order to sensitize tumor cells to progesterone therapy in endometrial cancer. We developed stable PR reporter gene containing endometrial cancer cell lines monitoring the endogenous PR expression by inserting mCherry and hygromycin resistant gene at the endogenous PR gene locus by CRISPR/Cas9-mediated genome editing technique. This allows efficient, real-time monitoring of PR expression in its native epigenetic landscape. Reporter gene expression faithfully reflects and amplifies PR expression following treatment with drugs known to induce PR expression. Small molecular PR inducers have been identified from the FDA-approved 1018 drug library and tested for their ability to restore PR expression. Additionally, several candidate PR repressors have been identified by screening the genome-wide CRISPR knockout (GeCKO) library. This novel endogenous PR reporter gene system facilitates the discovery of a new treatment strategy to enhance PR expression and further sensitize progestin therapy in endometrial cancer. These tools provide a systematic, unbiased approach for monitoring target gene expression, allowing for novel drug discovery and mechanistic exploration.

Co-Targeting ErbB Receptors and the PI3K/AKT Axis in Androgen-Independent Taxane-Sensitive and Taxane-Resistant Human Prostate Cancer Cells

Simple Summary

Advanced prostate cancer that has progressed after standard therapies such as hormone therapy and taxane-based chemotherapies is an invariably lethal disease state with limited treatment options. There remains an important need to continue to identify new treatment approaches for such patients. We used two cell culture models of prostate cancer that are resistant to hormonal therapy and chemotherapy, and which also manifest some characteristics that are often associated with advanced prostate cancer, such as neuroendocrine differentiation, to evaluate the potential anti-cancer effects of targeting the key molecules, ErbB receptors and AKT. Using several complementary approaches, we found that the concurrent targeting of ErbB receptors and AKT with specific inhibitors was more effective than targeting each of them individually, independent of the underlying molecular characteristics or relative degrees of resistance to the taxanes that defined the prostate cancer models that were studied. Enhanced anti-tumor responses occurred both in vitro and in vivo with dual targeting, with the consistent inhibition particularly of AKT occurring in both settings. These studies provide a framework to evaluate the role of signal pathway modulation as a potential therapeutic strategy in treatment-refractory prostate cancer.

Abstract

Using two representative models of androgen-independent prostate cancer (PCa), PC3 and DU145, and their respective paclitaxel- and docetaxel-resistant derivatives, we explored the anti-tumor activity of targeting the ErbB receptors and AKT using small-molecule kinase inhibitors. These cells manifest varying degrees of neuroendocrine differentiation characteristics and differ in their expression of functional PTEN. Although the specific downstream signaling events post the ErbB receptor and AKT co-targeting varied between the PC3- and DU145-lineage cells, synergistic anti-proliferative and enhanced pro-apoptotic responses occurred across the wild-type and the taxane-resistant cells, independent of their basal AKT activation state, their degree of paclitaxel- or docetaxel-resistance, or whether this resistance was mediated by the ATP Binding Cassette transport proteins. Dual targeting also led to enhanced anti-tumor responses in vivo, although there was pharmacodynamic discordance between the PCa cells in culture versus the tumor xenografts in terms of the relative activation and inhibition states of AKT and ERK under basal conditions and upon AKT and/or ErbB targeting. The consistent inhibition, particularly of AKT, occurred both in vitro and in vivo, independent of the underlying PTEN status. Thus, co-targeting AKT with ErbB, and possibly other partners, may be a useful strategy to explore further for potential therapeutic effect in advanced PCa.

Ipatasertib, an oral AKT inhibitor, inhibits cell proliferation and migration, and induces apoptosis in serous endometrial cancer

Ipatasertib (IPAT) is an orally administered, selective protein kinase B (AKT) inhibitor with promising data in solid tumors in both pre-clinical studies and clinical trials. Given that the PI3K/AKT/mTOR pathway is frequently dysregulated in uterine serous carcinoma (USC), we aimed to explore the functional impact of IPAT on anti-tumorigenic activity in USC cell lines and primary cultures of USC. We found that IPAT significantly inhibited cell proliferation and colony formation in a dose-dependent manner in USC cells. Induction of cell cycle arrest and apoptosis was observed in IPAT-treated ARK1 and SPEC-2 cells. Treatment with IPAT resulted in reduced adhesion and invasion of both cell lines with a concomitant decrease in the expression of Snail, Slug, and N-Cadherin. Compared with single-drug treatment, the combination of IPAT and paclitaxel synergistically reduced cell proliferation and increased the activity of cleaved caspase 3 in both cell lines. Additionally, IPAT inhibited growth in four of five primary USC cultures, and three of five primary cultures also exhibited synergistic growth inhibition when paclitaxel and IPAT were combined. These results support that IPAT appears to be a promising targeted agent in the treatment of USC.

Ad-VT enhances the sensitivity of chemotherapy-resistant lung adenocarcinoma cells to gemcitabine and paclitaxel in vitro and in vivo

Background One of the main challenges in the clinical treatment of lung cancer is resistance to chemotherapeutic drugs. P-glycoprotein (P-gp)-mediated drug resistance is the main obstacle to successfully implementing microtubule-targeted tumor chemotherapy. Purpose In this study, we explored the effect of Ad-hTERTp-E1a-Apoptin (Ad-VT) on drug-resistant cell lines and the molecular mechanism by which Ad-VT combined with chemotherapy affects drug-resistant cells and parental cells. Methods In vitro, cell proliferation, colony formation, resistance index (RI), apoptosis and autophagy assays were performed. Protein expression was analyzed by Western blotting. Finally, a xenograft tumor model in nude mice was used to detect tumor growth and evaluate histological characteristics. Results Our results showed that Ad-VT had an obvious killing effect on A549, A549/GEM and A549/Paclitaxel cancer cells, and the sensitivity of drug-resistant cell lines to Ad-VT was significantly higher than that of parental A549 cells. Compared with A549 cells, A549/GEM and A549/Paclitaxel cells had higher autophagy levels and higher viral replication ability. Ad-VT decreased the levels of p-PI3k, p-Akt and p-mTOR and the expression of P-gp. In vivo, Ad-VT combined with chemotherapy can effectively inhibit the growth of chemotherapy-resistant tumors and prolong the survival of mice. Conclusions Thus, the combination of Ad-VT and chemotherapeutic drugs will be a promising strategy to overcome chemoresistance.

EPHA2 Promotes the Invasion and Migration of Human Tongue Squamous Cell Carcinoma Cal-27 Cells by Enhancing AKT/mTOR Signaling Pathway

EPHA2 is a member of the ephrin receptor tyrosine kinase family and is closely related to the malignant tumor progression. The effect of EPHA2 on OSCC is not clear. This study explored the role of EPHA2 and AKT/mTOR signaling pathways in Cal-27 cell invasion and migration. The expression of EPHA2 and EPHA4 in human OSCC and normal oral tissue was detected by immunohistochemistry. EPHA2-overexpressing and EPHA2-knockdown Cal-27 cells were established, and the cells were treated with an AKT inhibitor (MK2206) and mTOR inhibitor (RAD001). The expression of EPHA2 was detected by qRT-PCR, cell proliferation was evaluated by MTT assay, cell migration and invasion were examined by scratch and Transwell assay, and cell morphology and apoptosis were assessed by Hoechst 33258 staining. Western blot was performed to detect the expression of proteins related to AKT/mTOR signaling, cell cycle, and pseudopod invasion. EPHA2 and EPHA4 were highly expressed in clinical human OSCC. Overexpression of EPHA2 promoted the proliferation, migration, and invasion of Cal-27 cells, inhibited cell cycle blockage and apoptosis, and enhanced the activity of the AKT/mTOR signaling pathway. MK2206 (AKT inhibitor) and RAD001 (mTOR inhibitor) reversed the effect of EPHA2 overexpression on the biological behavior of Cal-27 cells. EPHA2 promotes the invasion and migration of Cal-27 human OSCC cells by enhancing the AKT/mTOR signaling pathway.

Human-Derived Model Systems in Gynecological Cancer Research

The human female reproductive tract (FRT) is a complex system that combines series of organs, including ovaries, fallopian tubes, uterus, cervix, vagina, and vulva; each of which possesses unique cellular characteristics and functions. This versatility, in turn, allows for the development of a wide range of epithelial gynecological cancers with distinct features. Thus, reliable model systems are required to better understand the diverse mechanisms involved in the regional pathogenesis of the reproductive tract and improve treatment strategies. Here, we review the current human-derived model systems available to study the multitude of gynecological cancers, including ovarian, endometrial, cervical, vaginal, and vulvar cancer, and the recent advances in the push towards personalized therapy.

The AKT inhibitor MK2206 suppresses airway inflammation and the pro‑remodeling pathway in a TDI‑induced asthma mouse model

The cellular and molecular mechanisms via which MK2206, an AKT inhibitor, prevents the activation of AKT in toluene diisocyanate (TDI)‑induced asthma remain unclear. Thus, the present study aimed to evaluate the potential effects of MK2206 on airway AKT activation, inflammation and remodeling in a TDI‑induced mouse model of asthma. A total of 24 BALB/c mice were selected and randomly divided into untreated (AOO), asthma (TDI), MK2206 (TDI + MK2206), and dexamethasone (TDI + DEX) groups. Phosphorylated AKT (p‑AKT), total AKT, airway remodeling indices, α‑smooth muscle actin (α‑SMA) and collagen I levels in pulmonary tissue were measured using western blotting. Airway inflammation factors, including interleukin (IL)‑4, ‑5, ‑6, and ‑13 in bronchoalveolar lavage fluid (BALF) and IgE in serum, were determined using ELISA. Additionally, the airway hyperresponsiveness (AHR) and pulmonary pathology of all groups were evaluated. The results of the present study demonstrated that p‑AKT levels in lung protein lysate were upregulated, and neutrophil, eosinophil and lymphocyte counts were increased in the lungs obtained from the asthma group compared with the AOO group. Both MK2206 and DEX treatment in TDI‑induced mice resulted not only in the attenuation of AKT phosphorylation, but also reductions in neutrophil, eosinophil and lymphocyte counts in the lungs of mice in the asthma group. Consistently, increases in the levels of the inflammatory cytokines IL‑4, ‑5, ‑6 and ‑13 analyzed in BALF, and serum IgE in the TDI group were demonstrated to be attenuated in the TDI + MK2206 and TDI + DEX groups. Furthermore, α‑SMA and AHR were significantly attenuated in the TDI + MK2206 group compared with the TDI group. These results revealed that MK2206 not only inhibited AKT activation, but also served a role in downregulating airway inflammation and airway remodeling in chemical‑induced asthma. Therefore, the findings of the present study may provide important insight into further combination therapy.

A Phase I Study of Dinaciclib in Combination With MK-2206 in Patients With Advanced Pancreatic Cancer

The combination of drugs targeting Ral and PI3K/AKT signaling has antitumor efficacy in preclinical models of pancreatic cancer. We combined dinaciclib (small molecule cyclin dependent kinase inhibitor with MK-2206 (Akt inhibitor) in patients with previously treated/metastatic pancreatic cancer. Patients were treated with dinaciclib (6-12 mg/m² i.v.) and MK-2206 (60-135 mg p.o.) weekly. Tumor biopsies were performed to measure pAKT, pERK, and Ki67 at baseline and after one completed cycle (dose level 2 and beyond). Thirty-nine patients participated in the study. The maximum tolerated doses were dinaciclib 9 mg/m² and MK-2206 135 mg. Treatment-related grade 3 and 4 toxicities included neutropenia, lymphopenia, anemia, hyperglycemia, hyponatremia, and leukopenia. No objectives responses were observed. Four patients (10%) had stable disease as their best response. At the recommended dose, median survival was 2.2 months. Survival rates at 6 and 12 months were 11% and 5%, respectively. There was a nonsignificant reduction in pAKT composite scores between pretreatment and post-treatment biopsies (mean 0.76 vs. 0.63; P = 0.635). The combination of dinaciclib and MK-2206 was a safe regimen in patients with metastatic pancreatic cancer, although without clinical benefit, possibly due to not attaining biologically effective doses. Given the strong preclinical evidence of Ral and AKT inhibition, further studies with better tolerated agents should be considered.

Targeted therapies in gynecological cancers: a comprehensive review of clinical evidence

Advanced and recurrent gynecological cancers are associated with poor prognosis and lack of effective treatment. The developments of the molecular mechanisms on cancer progression provide insight into novel targeted therapies, which are emerging as groundbreaking and promising cancer treatment strategies. In gynecologic malignancies, potential therapeutic targeted agents include antiangiogenic agents, poly (ADP-ribose) polymerase (PARP) inhibitors, tumor-intrinsic signaling pathway inhibitors, selective estrogen receptor downregulators, and immune checkpoint inhibitors. In this article, we provide a comprehensive review of the clinical evidence of targeted agents in gynecological cancers and discuss the future implication.

DDB1 E3 ligase controls dietary fructose-induced ChREBPα stabilization and liver steatosis via CRY1

Fructose over-consumption contributes to the development of liver steatosis in part by stimulating ChREBPα-driven de novo lipogenesis. However, the mechanisms by which fructose activates ChREBP pathway remain largely undefined. Here we performed affinity purification of ChREBPα followed by mass spectrometry and identified DDB1 as a novel interaction protein of ChREBPα in the presence of fructose. Depletion and overexpression of Ddb1 showed opposite effects on the ChREBPα stability in hepatocytes. We next tested the impact of hepatic Ddb1 deficiency on the fructose-induced ChREBP pathway. After 3-week high-fructose diet feeding, both Ddb1 liver-specific knockout and AAV-TBG-Cre-injected Ddb1^flox/flox mice showed significantly reduced ChREBPα, lipogenic enzymes, as well as triglycerides in the liver. Mechanistically, DDB1 stabilizes ChREBPα through CRY1, a known ubiquitination target of DDB1 E3 ligase. Finally, overexpression of a degradation-resistant CRY1 mutant (CRY1-585KA) reduces ChREBPα and its target genes in the mouse liver following high-fructose diet feeding. Our data revealed DDB1 as an intracellular sensor of fructose intake to promote hepatic de novo lipogenesis and liver steatosis by stabilizing ChREBPα in a CRY1-dependent manner.

MK2206 Enhances Cisplatin-Induced Cytotoxicity and Apoptosis in Testicular Cancer Through Akt Signaling Pathway Inhibition

OBJECTIVE

To improve conventional chemotherapeutic efficacy, it is significant to identify novel molecular markers for chemosensitivity as well as possible molecules accelerating cell-killing mechanisms. In this study, we attempted to elucidate how MK2206, an allosteric Akt inhibitor, enhances the cisplatin (CDDP)-induced cytotoxicity and apoptosis in testicular cancer.

MATERIALS AND METHODS

We checked three testicular cancer cell lines for the expression of phospho(p)-Akt and its downstream molecules targets by Western blot. The potential antitumor effects were analyzed by MTT assay in vitro and by subcutaneous xenograft models in vivo. The cell invasion was analyzed by transwell invasion assay, and the activities of Akt signaling pathway and expression of apoptosis-related proteins were measured by Western blot.

RESULTS

Our results indicated that there was overactivation of p-Akt and its downstream molecules in testicular cancer cell lines compared with normal testis epithelium cells. MK2206 (600 nM) inhibited cell invasion in TCAM-2 and P19 cell lines and significantly increased the susceptibility of testicular cancer to CDDP. Combined with CDDP, MK2206 potentiated CDDP-induced cytotoxicity and apoptosis, with repressed expression of p-Akt and its downstream targets. The subcutaneous xenograft models also showed that a combined CDDP/MK2206 therapy completely suppressed tumor growth without any side effects.

CONCLUSION

These results suggested that the concomitant use of MK2206 could enhance the CDDP-induced cytotoxicity and apoptosis in testicular cancer with the suppressed expression of Akt pathway.

Pathogenesis and Clinical Management of Uterine Serous Carcinoma

Uterine serous carcinoma (USC) is an aggressive variant of endometrial cancer that has not been well characterized. It accounts for less than 10% of all endometrial cancers and 80% of endometrial cancer–related deaths. Currently, staging surgery together with chemotherapy or radiotherapy, especially vaginal cuff brachytherapy, is the main treatment strategy for USC. Whole-exome sequencing combined with preclinical and clinical studies are verifying a series of effective and clinically accessible inhibitors targeting frequently altered genes, such as HER2 and PI3K3CA, in varying USC patient populations. Some progress has also been made in the immunotherapy field. The PD-1/PD-L1 pathway has been found to be activated in many USC patients, and clinical trials of PD-1 inhibitors in USC are underway. This review updates the progress of research regarding the molecular pathogenesis and putative clinical management of USC.

Hormonal Regulation of Patient-Derived Endometrial Cancer Stem-like Cells Generated by Three-Dimensional Culture

Low-grade and early-stage endometrial cancer usually has a favorable prognosis, whereas recurrent or metastatic disease is often difficult to cure. Thus, the molecular mechanisms underlying advanced pathophysiology remain to be elucidated. From the perspective of the origin of advanced endometrial cancer, the characterization of cancer stem-like cells (CSCs) will be the first step toward the development of clinical management. We established long-term culturable patient-derived cancer cells (PDCs) from patient endometrial tumors by spheroid cell culture, which is favorable for the enrichment of CSCs. PDC-derived xenograft tumors were generated in immunodeficient NOD/Shi-scid, IL-2RγKO Jic mice. Morphologically, PDCs derived from three distinct patient samples and their xenograft tumors recapitulated the corresponding original patient tumors. Of note, CSC-related genes including ALDH1A1 were upregulated in all of these PDCs, and the therapeutic potentiality of aldehyde dehydrogenase inhibitors was demonstrated. In addition, these PDCs and their patient-derived xenograft (PDX) models exhibited distinct characteristics on the basis of their hormone responsiveness and metastatic features. Interestingly, genes associated with inflammation and tumor immunity were upregulated by 17β-estradiol in PDC lines with high estrogen receptor expression and were also overexpressed in secondary PDCs obtained from metastatic tumor models. These results suggest that PDC and PDX models from endometrial cancer specimens would be useful to elucidate CSC traits and to develop alternative diagnostic and therapeutic options for advanced disease.

Phosphorylation-Dependent Inhibition of Akt1

Protein kinase B (Akt1) is a proto-oncogene that is overactive in most cancers. Akt1 activation requires phosphorylation at Thr308; phosphorylation at Ser473 further enhances catalytic activity. Akt1 activity is also regulated via interactions between the kinase domain and the N-terminal auto-inhibitory pleckstrin homology (PH) domain. As it was previously difficult to produce Akt1 in site-specific phosphorylated forms, the contribution of each activating phosphorylation site to auto-inhibition was unknown. Using a combination of genetic code expansion and in vivo enzymatic phosphorylation, we produced Akt1 variants containing programmed phosphorylation to probe the interplay between Akt1 phosphorylation status and the auto-inhibitory function of the PH domain. Deletion of the PH domain increased the enzyme activity for all three phosphorylated Akt1 variants. For the doubly phosphorylated enzyme, deletion of the PH domain relieved auto-inhibition by 295-fold. We next found that phosphorylation at Ser473 provided resistance to chemical inhibition by Akti-1/2 inhibitor VIII. The Akti-1/2 inhibitor was most effective against pAkt1^T308 and showed four-fold decreased potency with Akt1 variants phosphorylated at Ser473. The data highlight the need to design more potent Akt1 inhibitors that are effective against the doubly phosphorylated and most pathogenic form of Akt1.

Patient-Derived Xenograft Models for Endometrial Cancer Research

Endometrial cancer (EC) is the most common malignancy of the genital tract among women in developed countries. Recently, a molecular classification of EC has been performed providing a system that, in conjunction with histological observations, reliably improves EC classification and enhances patient management. Patient-derived xenograft models (PDX) represent nowadays a promising tool for translational research, since they closely resemble patient tumour features and retain molecular and histological features. In EC, PDX models have already been used, mainly as an individualized approach to evaluate the efficacy of novel therapies and to identify treatment-response biomarkers; however, their uses in more global or holistic approaches are still missing. As a collaborative effort within the ENITEC network, here we describe one of the most extensive EC PDX cohorts developed from primary tumour and metastasis covering all EC subtypes. Our models are histologically and molecularly characterized and represent an excellent reservoir of EC tumour samples for translational research. This review compiles the information on current methods of EC PDX generation and their utility and provides new perspectives for the exploitation of these valuable tools in order to increase the success ratio for translating results to clinical practice.

Apoptin-derived peptide reverses cisplatin resistance in gastric cancer through the PI3K-AKT signaling pathway

The prognosis of gastric cancer (GC) remains poor due to clinical drug resistance, and novel drugs are urgently needed. Apoptin-derived peptide (AdP) is an antitumor polypeptide constructed in our laboratory that has been used to combat cisplatin (CDDP) resistance in GC cells. MTT and colony-formation assays and Hoechst 33342 staining were used to measure the cytotoxicity of CDDP and AdP in GC cells. Cell apoptosis was measured using an Annexin-V-FITC/PI dual staining assay. Western blot analysis was conducted to detect the expression of proteins in the PI3K/AKT signaling pathway and resistance-related markers. AdP exerted a specific cytotoxic effect on GC cells and CDDP-resistant GC cells in a concentration- and time-dependent manner. AdP also suppressed cell invasion and migration. Additionally, AdP inhibited the expression of p85, AKT, p-p85, p-AKT, multidrug resistance 1 (MDR1), and aryl hydrocarbon nuclear translocator (ARNT) in the PI3K/AKT/ARNT signaling pathway, which promoted apoptosis and necrosis in GC cells. AdP promoted apoptosis in CDDP-resistant GC cells by suppressing the PI3K/AKT/ARNT signaling pathway and might be considered a candidate agent for the clinical treatment of cisplatin-resistant GC.

Targeted AKT Inhibition in Prostate Cancer Cells and Spheroids Reduces Aerobic Glycolysis and Generation of Hyperpolarized [1-13C] Lactate

The PI3K/AKT/mTOR (PAM) signaling pathway is frequently mutated in prostate cancer. Specific AKT inhibitors are now in advanced clinical trials, and this study investigates the effect of MK2206, a non-ATP-competitive inhibitor, on the cellular metabolism of prostate cancer cells. We observed a reduction in cell motility and aerobic glycolysis in prostate cancer cells with treatment. These changes were not accompanied by a reduction in the ratio of high-energy phosphates or a change in total protein levels of enzymes and transporters involved in glycolysis. However, a decreased ratio of NAD+/NADH was observed, motivating the use of hyperpolarized magnetic resonance spectroscopy (HP-MRS) to detect treatment response. Spectroscopic experiments were performed on tumor spheroids, 3D structures that self-organize in the presence of an extracellular matrix. Treated spheroids showed decreased lactate production with on-target inhibition confirmed using IHC, demonstrating that HP-MRS can be used to probe treatment response in prostate cancer spheroids and can provide a biomarker for treatment response. Mol Cancer Res; 16(3); 453-60. ©2018 AACR.