Galeterone and its analogs inhibit Mnk-eIF4E axis, synergize with gemcitabine, impede pancreatic cancer cell migration, invasion and proliferation and inhibit tumor growth in mice

Selective and effective suppression of pancreatic cancer through MNK inhibition

Objective: The study aimed to explore the role of the Wnt/β-catenin signaling pathway in pancreatic cancer progression and chemoresistance, with a focus on identifying specific factors that distinguish between normal and tumor cells, thereby offering potential therapeutic targets.

Materials and Methods: We analyzed levels of total and phosphorylated eukaryotic translation initiation factor 4E (eIF4E) and β-catenin in pancreatic cancer and normal pancreatic tissues. Functional assays were used to assess the impact of eIF4E phosphorylation on β-catenin signaling, cell proliferation, and chemoresistance, with MNK kinase involvement determined through gene depletion studies. The MNK kinase inhibitor eFT508 was evaluated for its effects on eIF4E phosphorylation, β-catenin activation, and cell viability in both in vitro and in vivo models of pancreatic cancer.

Results: Both total and phosphorylated eIF4E, along with β-catenin, were significantly elevated in pancreatic cancer tissues compared to normal tissues. Phosphorylation of eIF4E at serine 209 was shown to activate β-catenin signaling, enhance cell proliferation, and contribute to chemoresistance in pancreatic cancer. Importantly, these effects were dependent on MNK kinase activity. Depletion of eIF4E reduced cell viability in both pancreatic cancer and normal cells, while depletion of MNK selectively decreased viability in pancreatic cancer cells. Treatment with eFT508 effectively inhibited eIF4E phosphorylation, suppressed β-catenin activation, and reduced pancreatic cancer cell growth and survival in vitro and in vivo, with minimal impact on normal cells.

Conclusions: The MNK-eIF4E-β-catenin axis plays a critical role in pancreatic cancer progression and chemoresistance, distinguishing pancreatic cancer cells from normal cells. Targeting MNK kinases with inhibitors like eFT508 presents a promising therapeutic strategy for pancreatic cancer, with potential for selective efficacy and reduced toxicity.

Biodegradable nanocarrier of gemcitabine and tocopherol succinate synergistically ameliorates anti-proliferative response in MIA PaCa-2 cells

Gemcitabine (GEM) is an important chemotherapeutic agent used alone or in combination with other anticancer agents for the treatment of various solid tumors. In this study, the potential of a dietary supplement, α-tocopherol succinate (TOS) was investigated in combination with GEM by utilizing human serum albumin-based nanoparticles (HSA NPs). The developed nanoparticles were characterized using DLS, SEM and FTIR and evaluated in a panel of cell lines to inspect cytotoxic efficacy. The ratio metric selected combination of the NPs was further investigated in human pancreatic cancer cell line (MIA PaCa-2 cells) to assess the cellular death mechanism via a myriad of biochemical and bio-analytical assays including nuclear morphometric analysis by DAPI staining, ROS generation, MMP loss, intracellular calcium release, in vitro clonogenic assay, cell migration assay, cell cycle analysis, immunocytochemical staining followed by western blotting, Annexin V-FITC and cellular uptake studies. The desolvation-crosslinking method was used to prepare the NPs. The average size of TOS-HSA NPs and GEM-HSA NPs was found to be 189.47 ± 5 nm and 143.42 ± 7.4 nm, respectively. In combination, the developed nanoparticles exhibited synergism by enhancing cytotoxicity in a fixed molar ratio. The selected combination also significantly triggered ROS generation and mitochondrial destabilization, alleviated cell migration potential and clonogenic cell survival in MIA PaCa-2 cells. Further, cell cycle analysis, Annexin-V FITC assay and caspase-3 activation, up regulation of Bax and down regulation of Bcl-2 protein confirmed the occurrence of apoptotic event coupled with the G0/G1 phase arrest. Nanocarriers based this combination also offered approximately 14-folds dose reduction of GEM. Overall, the combined administration of TOS-HSA NPs and GEM-HSA NPs showed synergistic cytotoxicity accompanied with dose reduction of the gemcitabine. These encouraging findings could have implication in designing micronutrient based-combination therapy with gemcitabine and demands further investigation.

Salinization Dramatically Enhance the Anti-Prostate Cancer Efficacies of AR/AR-V7 and Mnk1/2 Molecular Glue Degraders, Galeterone and VNPP433-3β Which Outperform Docetaxel and Enzalutamide in CRPC CWR22Rv1 Xenograft Mouse Model

Galeterone, 3β-(hydroxy)-17-(1H-benzimidazole-1-yl)androsta-5,16-diene (Gal, 1) and VNPP433-3β, 3β-(1H-imidazole-1-yl-17-(1H-benzimidazole-1-yl)androsta-5,16-diene (2) are potent molecular glue degrader modulators of AR/AR-V7 and Mnk1/2-eIF4E signaling pathways, and are promising Phase 3 and Phase 1 drug candidates, respectively. Because appropriate salts can be utilized to create new chemical entities with enhanced aqueous solubility, in vivo pharmacokinetics, and enhanced in vitro and in vivo efficacies, the monohydrochloride salt of Gal (3) and the mono- and di-hydrochlorides salts of compound 2, compounds 4 and 5, respectively, were synthesized. The salts were characterized using 1H NMR, 13C NMR and HRMS analyses. Compound 3 displayed enhanced in vitro antiproliferative activity (7.4-fold) against three prostate cancer cell lines but surprisingly decreased plasma exposure in the pharmacokinetics study. The antiproliferative activities of the compound 2 salts (4 and 5) were equivalent to that of compound 2, but their oral pharmacokinetic profiles were significantly enhanced. Finally, and most importantly, oral administration of the parent compounds (1 and 2) and their corresponding salts (3, 4 and 5) caused dose-dependent potent inhibition/regression of aggressive and difficult-to-treat CWR22Rv1 tumor xenografts growth, with no apparent host toxicities and were highly more efficacious than the blockbuster FDA-approved prostate cancer drugs, Enzalutamide (Xtandi) and Docetaxel (Taxotere). Thus, the HCl salts of Gal (3) and VNPP433-3β (4 and 5) are excellent orally bioavailable candidates for clinical development.

Translational alterations in pancreatic cancer: a central role for the integrated stress response

mRNA translation is a key mechanism for cancer cell proliferation and stress adaptation. Regulation of this machinery implicates upstream pathways such as PI3K/AKT/mTOR, RAS/MEK/ERK and the integrated stress response (ISR), principally coordinating the translation initiation step. During the last decade, dysregulation of the mRNA translation process in pancreatic cancer has been widely reported, and shown to critically impact on cancer initiation, development and survival. This includes translation dysregulation of mRNAs encoding oncogenes and tumor suppressors. Hence, cancer cells survive a stressful microenvironment through a flexible regulation of translation initiation for rapid adaptation. The ISR pathway has an important role in chemoresistance and shows high potential therapeutic interest. Despite the numerous translational alterations reported in pancreatic cancer, their consequences are greatly underestimated. In this review, we summarize the different translation dysregulations described in pancreatic cancer, which make it invulnerable, as well as the latest drug discoveries bringing a glimmer of hope.

Progress in developing MNK inhibitors

The MNKs (mitogen-activated protein kinase-interacting protein kinases) phosphorylate eIF4E (eukaryotic initiation factor 4 E) at serine 209; eIF4E plays an important role in the translation of cytoplasmic mRNAs, all of which possess a 5' 'cap' structure to which eIF4E binds. Elevated levels of eIF4E, p-eIF4E and/or the MNK protein kinases have been found in many types of cancer, including solid tumors and leukemia. MNKs also play a role in metabolic disease. Regulation of the activities of MNKs (MNK1 and MNK2), control the phosphorylation of eIF4E, which in turn has a close relationship with the processes of tumor development, cell migration and invasion, and energy metabolism. MNK knock-out mice display no adverse effects on normal cells or phenotypes suggesting that MNK may be a potentially safe targets for the treatment of various cancers. Several MNK inhibitors or 'degraders' have been identified. Initially, some of the inhibitors were developed from natural products or based on other protein kinase inhibitors which inhibit multiple kinases. Subsequently, more potent and selective inhibitors for MNK1/2 have been designed and synthesized. Currently, three inhibitors (BAY1143269, eFT508 and ETC-206) are in various stages of clinical trials for the treatment of solid cancers or leukemia, either alone or combined with inhibitors of other protein kinase. In this review, we summarize the diverse MNK inhibitors that have been reported in patents and other literature, including those with activities in vitro and/or in vivo.

Anti-tumor Activities of 3-Hydroxy-3-methylglutaryl Coenzyme A (HMG-CoA) Reductase Inhibitors and Bisphosphonates in Pancreatic Cell Lines Which Show Poor Responses to Gemcitabine

Few therapeutic options exist for gemcitabine-resistant pancreatic cancer. In this study, we investigated the anti-cancer effects of 3-hydroxy-3-methylglutaryl (HMG)-CoA reductase inhibitors and bisphosphonates in pancreatic cancer cell lines (SUIT-2 and MIA PaCa-2) which show poor responses to gemcitabine, established through long-term culture in nutrient-deprived or gemcitabine-containing media. Under the nutrient-deprived condition, IC₅₀s for statins and bisphosphonates decreased and those for gemcitabine increased compared with those under normal conditions. In cells cultured long-term with gemcitabine, although IC₅₀s for gemcitabine increased, those for statins and bisphosphonates either slightly increased or remained unchanged. Thus, these drugs may be effective against pancreatic cancer cells which show poor responses to gemcitabine.

Galeterone sensitizes breast cancer to chemotherapy via targeting MNK/eIF4E and β-catenin

Aberrant activation of eIF4E signalling pathway is common in breast cancer and holds potential therapeutic options. In our work, galeterone as a chemical compound under clinical trials for the treatment of prostate cancer, was identified to be effective in targeting breast cancer cells via suppressing MNK-eIF4E and β-catenin. In despite of varying IC50, galeterone at nanomolar concentrations significantly decreased viability, proliferation and migration of a panel of breast cancer cell lines regardless of clinical subtypes and genetic mutations, and to a higher extent than in normal breast cells. Galeterone significantly enhanced the effects of chemotherapeutic drugs in reducing proliferation and viability but not migration. The in vivo efficacy of galeterone as single drug alone and its ability in augmenting chemotherapy's efficacy were also shown in breast cancer xenograft mouse model. Mechanism analysis demonstrated that galeterone decreased MNK1/2 level and phosphorylation of eIF4E. In addition, galeterone decreased β-catenin level via promoting GSK-3β-mediated β-catenin degradation, and furthermore that Akt but not CK1 was involved in β-catenin degradation by galeterone. Rescue studies demonstrated that both MNK/eIF4E and β-catenin were responsible for anti-breast cancer activity of galeterone. Our study provides pre-clinical evidence to initialize clinical trials for breast cancer using galeterone in combination with chemotherapy.

Phosphorylation of the mRNA cap-binding protein eIF4E and cancer

Dysregulated protein synthesis is frequently involved in oncogenesis and cancer progression. Translation initiation is thought to be the rate-limiting step in protein synthesis, and the mRNA 5' cap-binding protein eukaryotic translation initiation factor 4E (eIF4E) is a pivotal factor that initiates translation. The activities of eIF4E are regulated at multiple levels, one of which is through its phosphorylation at Serine 209 by the mitogen-activated protein kinase-interacting kinases (MNKs, including MNK1 and MNK2). Benefiting from novel mouse genetic tools and pharmacological MNK inhibitors, our understanding of a role for eIF4E phosphorylation in tumor biology and cancer therapy has greatly evolved in recent years. Importantly, recent studies have found that the level of eIF4E phosphorylation is frequently upregulated in a wide variety of human cancer types, and phosphorylation of eIF4E drives a number of important processes in cancer biology, including cell transformation, proliferation, apoptosis, metastasis and angiogenesis. The MNK-eIF4E axis is being assessed as a therapeutic target either alone or in combination with other therapies in different cancer models. As novel MNK inhibitors are being developed, experimental studies bring new hope to cure human cancers that are not responsive to traditional therapies. Herein we review recent progress on our understanding of a mechanistic role for phosphorylation of eIF4E in cancer biology and therapy.

Deeping in the Role of the MAP-Kinases Interacting Kinases (MNKs) in Cancer

The mitogen-activated protein kinase (MAPK)-interacting kinases (MNKs) are involved in oncogenic transformation and can promote metastasis and tumor progression. In human cells, there are four MNKs isoforms (MNK1a/b and MNK2a/b), derived from two genes by alternative splicing. These kinases play an important role controlling the expression of specific proteins involved in cell cycle, cell survival and cell motility via eukaryotic initiation factor 4E (eIF4E) regulation, but also through other substrates such as heterogeneous nuclear ribonucleoprotein A1, polypyrimidine tract-binding protein-associated splicing factor and Sprouty 2. In this review, we provide an overview of the role of MNK in human cancers, describing the studies conducted to date to elucidate the mechanism involved in the action of MNKs, as well as the development of MNK inhibitors in different hematological cancers and solid tumors.

Galeterone and The Next Generation Galeterone Analogs, VNPP414 and VNPP433-3β Exert Potent Therapeutic Effects in Castration-/Drug-Resistant Prostate Cancer Preclinical Models In Vitro and In Vivo

These studies compared the efficacies of our clinical agent galeterone (Gal) and the FDA-approved prostate cancer drug, enzalutamide (ENZ) with two lead next generation galeterone analogs (NGGAs), VNPP414 and VNPP433-3β, using prostate cancer (PC) in vitro and in vivo models. Antitumor activities of orally administered agents were also assessed in CWR22Rv1 tumor-bearing mice. We demonstrated that Gal and NGGAs degraded AR/AR-V7 and Mnk1/2; blocked cell cycle progression and proliferation of human PC cells; induced apoptosis; inhibited cell migration, invasion, and putative stem cell markers; and reversed the expression of epithelial-to-mesenchymal transition (EMT). In addition, Gal/NGGAs (alone or in combination) also inhibited the growth of ENZ-, docetaxel-, and mitoxantrone-resistant human PC cell lines. The NGGAs exhibited improved pharmacokinetic profiles over Gal in mice. Importantly, in vivo testing showed that VNPP433-3β (at 7.53-fold lower equimolar dose than Gal) markedly suppressed (84% vs. Gal, 47%; p < 0.01) the growth of castration-resistant PC (CRPC) CWR22Rv1 xenograft tumors, with no apparent host toxicity. ENZ was ineffective in this CRPC xenograft model. In summary, our findings show that targeting AR/AR-V7 and Mnk1/2 for degradation represents an effective therapeutic strategy for PC/CRPC treatment and supports further development of VNPP433-3β towards clinical investigation.

Targeting E-cadherin expression with small molecules for digestive cancer treatment

Digestive system cancers, mainly including gastric cancer, hepatocellular carcinoma, pancreatic cancer, and colorectal cancer, are major public health problems and lead to serious cancer-related deaths worldwide. Clinically, treatment strategies of these cancers include surgery, chemotherapy, and immunotherapy. Although successful resection and chemotherapeutic drugs have improved the treatment level, the survival rate of patients with advanced digestive system cancers remains still low primarily due to tumor metastasis. E-cadherin, the prototypical member of the type-1 classical cadherins, has been characrized as an important molecule in epithelial-mesenchymal transition (EMT) process. Loss of E-cadherin is able to induce EMT process, which is associated with cancer stem cells and drug resistance in human cancer. Therefore, restoring E-cadherin could be a useful strategy for reversal of EMT and overcoming drug resistance. In this review, we describe pharmacological small molecules targeting E-cadherin expression for the treatment of digestive system cancers, which have emerged in the recent 5 years. We hope these compounds could be potentially used for treating cancer in the near future.

MAP Kinase-Interacting Kinase 1 Promotes Proliferation and Invasion of Hepatocellular Carcinoma and Is an Unfavorable Prognostic Biomarker

Background

Hepatocellular carcinoma (HCC) accounts for one of the most prevalent tumor types in the world. The MAP kinase-interacting kinase 1 (MNK1) functions downstream of MAP kinases such as p38 and ERK, and its potential role in cancer development is being uncovered. The aim of this study was to investigate the expression and function of MNK1 in HCC.

Material/Methods

Immunohistochemical staining and quantitative PCR were performed to explore the expression of MNK1 in both HCC tissues and adjacent normal liver tissues. Chi-square test, univariate analysis, and multivariate analysis were conducted to statistically evaluate clinical significance of MNK1 in HCC. Proliferation, migration, and invasion capacities of HCC cells were assessed after overexpressing or silencing MNK1.

Results

Both the RNA and protein levels of MNK1 were upregulated in HCC tissues compared to normal liver tissues. High expression of MNK1 was correlated with advanced tumor stage and poor overall survival. Moreover, MNK1 was identified as a novel independent prognostic factor for HCC patients. Cellular studies showed that MNK1 can enhance the proliferation, migration, and invasion capacities of HCC cells, thereby promoting tumor progression.

Conclusions

High expression of MNK1 is frequent in HCC tissues, which promotes tumor proliferation and invasion, and is correlated with a poor overall survival. Targeting MNK1 may be a novel direction for the drug development of HCC therapy.

Targeting of protein translation as a new treatment paradigm for prostate cancer

PURPOSE OF REVIEW

The current overview will summarize some of the developments in the area of protein translation, including their relation to the therapeutic targeting of prostate cancer.

RECENT FINDINGS

Translational control, mediated by the rate-limiting eukaryotic translation initiation factor 4E (eIF4E), drives selective translation of several oncogenic proteins, thereby contributing to tumor growth, metastasis, and treatment resistance in various cancers, including prostate cancer. As an essential regulatory hub, several oncogenic hyperactive signaling pathways appear to converge on eIF4E to promote tumorigenesis. Several approaches that target the eIF4E-dependent protein translation network are being actively studied, and it is likely that some may ultimately emerge as promising anticancer therapeutics.

SUMMARY

An array of inhibitors has shown promise in targeting specific components of the translational machinery in several preclinical models of prostate cancer. It is hoped that some of these approaches may ultimately have relevance in improving the clinical outcomes of patients with advanced prostate cancer.