Overcoming Gemcitabine Resistance in Pancreatic Cancer Using the BCL-XL-Specific Degrader DT2216

BCL2L1 is regulated by the lncRNA MIR4435-2HG-miR-513a-5p-BCL2L1 ceRNA axis and serves as a biomarker for pancreatic adenocarcinoma treatment and prognosis

Pancreatic adenocarcinoma (PAAD) is one of the most malignant cancers. After escaping death, cancer cells are made more metastatic, aggressive, and also drug-resistant through anoikis resistance. The aim of this study is to explore the molecular mechanisms of anoikis-related genes in PAAD and to identify potential key biomarkers. We integrated information about PAAD from The Cancer Genome Atlas (TCGA) and The Genotype-Tissue Expression (GTEx) databases and identified anoikis-related gene BCL2L1 by survival analysis, univariate Cox regression analysis, and multifactorial Cox regression analysis. Various bioinformatics approaches showed that BCL2L1 was a valuable prognostic marker that might be involved in PAAD development and progression through different mechanisms, including cancer intervention, genomic heterogeneity, and RNA modifications. Our analysis showed that BCL2L1 expression also closely correlates with the expression of various immune checkpoint inhibitors. In particular, we found that long non-coding RNA MIR4435-2HG acted as ceRNA sponging miR-513a-5p to promote the expression of BCL2L1, thereby promoting pancreatic cancer cells proliferation. In conclusion, BCL2L1 expression regulated by the MIR4435-2HG-miR-513a-5p-BCL2L1 ceRNA axis might be used as a biomarker for cancer prognosis, treatment selection, and follow-up in PAAD patients.

GATA6 identifies an immune-enriched phenotype linked to favorable outcomes in patients with pancreatic cancer undergoing upfront surgery

This study underscores GATA6's role in distinguishing classical and basal-like pancreatic ductal adenocarcinoma (PDAC) phenotypes. Retrospective studies associate GATA6 immunohistochemistry (IHC) expression with survival outcomes, warranting prospective validation. In a prospective treatment-naive cohort of patients with resected PDAC, GATA6 IHC proves a prognostic discriminator, associating high GATA6 expression with extended survival and the classical PDAC phenotype. However, GATA6's prognostic significance is numerically lower after gemcitabine-based neoadjuvant chemoradiotherapy compared to its significance in patients treated with upfront surgery. Furthermore, GATA6 is implicated in immunomodulation, although a comprehensive investigation of its immunological role is lacking. Treatment-naive PDAC tumors with varying GATA6 expression yield distinct immunological landscapes. Tumors highly expressing GATA6 show reduced infiltration of immunosuppressive regulatory T cells and M2 macrophages but increased infiltration of immune-stimulating, antigen-presenting, and activated T cells. Our findings caution against solely relying on GATA6 for molecular subtyping in clinical trials and open avenues for exploring immune-based combination therapies.

Discovery of a potent Gilteritinib-based FLT3-PROTAC degrader for the treatment of Acute myeloid leukemia

Fms-like tyrosine receptor kinase 3 (FLT3) proteolysis targeting chimeras (PROTACs) emerge as a promising approach to overcome the limitations of FLT3 inhibitors, while the development of orally bioavailable FLT3-PROTACs faces great challenges. Here, we report the rational design and evaluation of a series of Gilteritinib-based FLT3-PROTACs. Among them, B3-2 exhibited the strongest antiproliferative activity against FLT3-ITD mutant AML cells, and significantly induced FLT3-ITD protein degradation. Mechanistic investigations demonstrated that B3-2 induced FLT3-ITD degradation in a ubiquitin-proteasome-dependent manner. More importantly, B3-2 exhibited an oral bioavailability of 5.65%, and oral administration of B3-2 showed good antitumor activity in MV-4-11 xenograft models. Furthermore, B3-2 showed strong antiproliferative activity against FLT3 resistant mutations, highlighting its potential in overcoming drug resistance.

CRISPR/Cas9-mediated silencing of CD44: unveiling the role of hyaluronic acid-mediated interactions in cancer drug resistance

A comprehensive overview of CD44 (CD44 Molecule (Indian Blood Group)), a cell surface glycoprotein, and its interaction with hyaluronic acid (HA) in drug resistance mechanisms across various types of cancer is provided, where CRISPR/Cas9 gene editing was utilized to silence CD44 expression and examine its impact on cancer cell behavior, migration, invasion, proliferation, and drug sensitivity. The significance of the HA-CD44 axis in tumor microenvironment (TME) delivery and its implications in specific cancer types, the influence of CD44 variants and the KHDRBS3 (KH RNA Binding Domain Containing, Signal Transduction Associated 3) gene on cancer progression and drug resistance, and the potential of targeting HA-mediated pathways using CRISPR/Cas9 gene editing technology to overcome drug resistance in cancer were also highlighted.

Hyperthermia improves gemcitabine sensitivity of pancreatic cancer cells by suppressing the EFNA4/β-catenin axis and activating dCK

Background

Previously, our investigations have underscored the potential of hyperthermia to improve the therapeutic efficacy of gemcitabine (GEM) in pancreatic cancer (PC). Nonetheless, the precise underlying mechanisms remain elusive.

Methods

We engineered two GEM-resistant PC cell lines (BxPC-3/GEM and PANC-1/GEM) and treated them with GEM alongside hyperthermia. The impact of hyperthermia on the therapeutic potency of GEM was ascertained through MTT assay, assessment of the concentration of its active metabolite dFdCTP, and evaluation of deoxycytidine kinase (dCK) activity. Lentivirus-mediated dCK silencing was further employed to validate its involvement in mediating the GEM-sensitizing effect of hyperthermia. The mechanism underlying hyperthermia-mediated dCK activation was explored using bioinformatics analyses. The interplay between hyperthermia and the ephrin A4 (EFNA4)/β-catenin/dCK axis was investigated, and their roles in GEM resistance was further explored via the establishment of xenograft tumor models in nude mice.

Results

Hyperthermia restored dCK expression in GEM-resistant cell lines, concurrently enhancing GEM sensitivity and fostering DNA damage and cell death. These observed effects were negated by dCK silencing. Regarding the mechanism, hyperthermia activated dCK by downregulating EFNA4 expression and mitigating β-catenin activation. Overexpression of EFNA4 activated the β-catenin while suppressing dCK, thus diminishing cellular GEM sensitivity-a phenomenon remediated by the β-catenin antagonist MSAB. Consistently, in vivo, hyperthermia augmented the therapeutic efficacy of GEM on xenograft tumors through modulation of the ephrin A4/β-catenin/dCK axis.

Conclusion

This study delineates the role of hyperthermia in enhancing GEM sensitivity of PC cells, primarily mediated through the suppression of the EFNA4/β-catenin axis and activation of dCK.

Tumor-targeted PROTAC prodrug nanoplatform enables precise protein degradation and combination cancer therapy

Proteolysis targeting chimeras (PROTACs) have emerged as revolutionary anticancer therapeutics that degrade disease-causing proteins. However, the anticancer performance of PROTACs is often impaired by their insufficient bioavailability, unsatisfactory tumor specificity and ability to induce acquired drug resistance. Herein, we propose a polymer-conjugated PROTAC prodrug platform for the tumor-targeted delivery of the most prevalent von Hippel-Lindau (VHL)- and cereblon (CRBN)-based PROTACs, as well as for the precise codelivery of a degrader and conventional small-molecule drugs. The self-assembling PROTAC prodrug nanoparticles (NPs) can specifically target and be activated inside tumor cells to release the free PROTAC for precise protein degradation. The PROTAC prodrug NPs caused more efficient regression of MDA-MB-231 breast tumors in a mouse model by degrading bromodomain-containing protein 4 (BRD4) or cyclin-dependent kinase 9 (CDK9) with decreased systemic toxicity. In addition, we demonstrated that the PROTAC prodrug NPs can serve as a versatile platform for the codelivery of a PROTAC and chemotherapeutics for enhanced anticancer efficiency and combination benefits. This study paves the way for utilizing tumor-targeted protein degradation for precise anticancer therapy and the effective combination treatment of complex diseases.

Targeted Protein Degraders- The Druggability Perspective

Targeted Protein degraders (TPDs) show promise in harnessing cellular machinery to eliminate disease-causing proteins, even those previously considered undruggable. Especially if protein turnover is low, targeted protein removal bestows lasting therapeutic effect over typical inhibition. The demonstrated safety and efficacy profile of clinical candidates has fueled the surge in the number of potential candidates across different therapeutic areas. As TPDs often do not comply with Lipinski's rule of five, developing novel TPDs and unlocking their full potential requires overcoming solubility, permeability and oral bioavailability challenges. Tailored in-vitro assays are key to precise profiling and optimization, propelling breakthroughs in targeted protein degradation.

Overview of epigenetic degraders based on PROTAC, molecular glue, and hydrophobic tagging technologies

Epigenetic pathways play a critical role in the initiation, progression, and metastasis of cancer. Over the past few decades, significant progress has been made in the development of targeted epigenetic modulators (e.g., inhibitors). However, epigenetic inhibitors have faced multiple challenges, including limited clinical efficacy, toxicities, lack of subtype selectivity, and drug resistance. As a result, the design of new epigenetic modulators (e.g., degraders) such as PROTACs, molecular glue, and hydrophobic tagging (HyT) degraders has garnered significant attention from both academia and pharmaceutical industry, and numerous epigenetic degraders have been discovered in the past decade. In this review, we aim to provide an in-depth illustration of new degrading strategies (2017-2023) targeting epigenetic proteins for cancer therapy, focusing on the rational design, pharmacodynamics, pharmacokinetics, clinical status, and crystal structure information of these degraders. Importantly, we also provide deep insights into the potential challenges and corresponding remedies of this approach to drug design and development. Overall, we hope this review will offer a better mechanistic understanding and serve as a useful guide for the development of emerging epigenetic-targeting degraders.

Acquired and intrinsic gemcitabine resistance in pancreatic cancer therapy: Environmental factors, molecular profile and drug/nanotherapeutic approaches

A high number of cancer patients around the world rely on gemcitabine (GEM) for chemotherapy. During local metastasis of cancers, surgery is beneficial for therapy, but dissemination in distant organs leads to using chemotherapy alone or in combination with surgery to prevent cancer recurrence. Therapy failure can be observed as a result of GEM resistance, threatening life of pancreatic cancer (PC) patients. The mortality and morbidity of PC in contrast to other tumors are increasing. GEM chemotherapy is widely utilized for PC suppression, but resistance has encountered its therapeutic impacts. The purpose of current review is to bring a broad concept about role of biological mechanisms and pathways in the development of GEM resistance in PC and then, therapeutic strategies based on using drugs or nanostructures for overcoming chemoresistance. Dysregulation of the epigenetic factors especially non-coding RNA transcripts can cause development of GEM resistance in PC and miRNA transfection or using genetic tools such as siRNA for modulating expression level of these factors for changing GEM resistance are suggested. The overexpression of anti-apoptotic proteins and survival genes can contribute to GEM resistance in PC. Moreover, supportive autophagy inhibits apoptosis and stimulates GEM resistance in PC cells. Increase in metabolism, glycolysis induction and epithelial-mesenchymal transition (EMT) stimulation are considered as other factors participating in GEM resistance in PC. Drugs can suppress tumorigenesis in PC and inhibit survival factors and pathways in increasing GEM sensitivity in PC. More importantly, nanoparticles can increase pharmacokinetic profile of GEM and promote its blood circulation and accumulation in cancer site. Nanoparticles mediate delivery of GEM with genes and drugs to suppress tumorigenesis in PC and increase drug sensitivity. The basic research displays significant connection among dysregulated pathways and GEM resistance, but the lack of clinical application is a drawback that can be responded in future.

Circular RNAs in pancreatic cancer progression

Pancreatic cancer (PC), typically diagnosed at relatively advanced stages with poor prognosis, is a dominant cause of cancer-related deaths worldwide. Accumulating evidence demonstrates that circular RNAs (circRNAs) are abnormally expressed in diverse tumors and affect tumorigenesis and progression. In this article, we examine the roles of circRNAs in regulation of PC progression. Additionally, circRNAs enriched in exosomes could be transferred among PC cells to modulate malignancy. Characterization of regulatory mechanisms involving circRNAs in general and PC specifically will enable earlier detection and potential development of therapeutic strategies.

Ubiquitin signaling in pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is a highly lethal malignant tumor of the digestive system, characterized by rapid progression and being prone to metastasis. Few effective treatment options are available for PDAC, and its 5-year survival rate is less than 9%. Many cell biological and signaling events are involved in the development of PDAC, among which protein post-translational modifications (PTMs), such as ubiquitination, play crucial roles. Catalyzed mostly by a three-enzyme cascade, ubiquitination induces changes in protein activity mainly by altering their stability in PDAC. Due to their role in substrate recognition, E3 ubiquitin ligases (E3s) dictate the outcome of the modification. Ubiquitination can be reversed by deubiquitylases (DUBs), which, in return, modified proteins to their native form. Dysregulation of E3s or DUBs that disrupt protein homeostasis is involved in PDAC. Moreover, the ubiquitination system has been exploited to develop therapeutic strategies, such as proteolysis-targeting chimeras (PROTACs). In this review, we summarize recent progress in our understanding of the role of ubiquitination in the development of PDAC and offer perspectives in the design of new therapies against this highly challenging disease.

A risk signature based on endoplasmic reticulum stress-associated genes predicts prognosis and immunity in pancreatic cancer

Introduction: The involvement of endoplasmic reticulum (ER) stress in cancer biology is increasingly recognized, yet its role in pancreatic cancer (PC) remains unclear. This study aims to elucidate the impact of ER stress on prognosis and biological characteristics in PC patients. Methods: A bioinformatic analysis was conducted using RNA-seq data and clinicopathological information from PC patients in the TCGA and ICGC databases. The ER stress-associated gene sets were extracted from MSigDB. ER stress-associated genes closely linked with overall survival (OS) of PC patients were identified via log-rank test and univariate Cox analysis, and further narrowed by LASSO method. A risk signature associated with ER stress was formulated using multivariate Cox regression and assessed through Kaplan-Meier curves, receiver operating characteristic (ROC) analyses, and Harrell's concordance index. External validation was performed with the ICGC cohort. The single-sample gene-set enrichment analysis (ssGSEA) algorithm appraised the immune cell infiltration landscape. Results: Worse OS in PC patients with high-risk signature score was observed. Multivariate analysis underscored our ER stress-associated signature as a valuable and independent predictor of prognosis. Importantly, these results based on TCGA were further validated in ICGC dataset. In addition, our risk signature was closely associated with homeostasis, protein secretion, and immune regulation in PC patients. In particular, PC microenvironment in the high-risk cluster exhibited a more immunosuppressive status. At last, we established a nomogram model by incorporating the risk signature and clinicopathological parameters, which behaves better in predicting prognosis of PC patients. Discussion: This comprehensive molecular analysis presents a new predictive model for the prognosis of PC patients, highlighting ER stress as a potential therapeutic target. Besides, the findings indicate that ER stress can have effect modulating PC immune responses.

AUM302, a novel triple kinase PIM/PI3K/mTOR inhibitor, is a potent in vitro pancreatic cancer growth inhibitor

Pancreatic cancer is one of the leading causes of cancer deaths, with pancreatic ductal adenocarcinoma (PDAC) being the most common subtype. Advanced stage diagnosis of PDAC is common, causing limited treatment opportunities. Gemcitabine is a frequently used chemotherapeutic agent which can be used as a monotherapy or in combination. However, tumors often develop resistance to gemcitabine. Previous studies show that the proto-oncogene PIM kinases (PIM1 and PIM3) are upregulated in PDAC compared to matched normal tissue and are related to chemoresistance and PDAC cell growth. The PIM kinases are also involved in the PI3K/AKT/mTOR pathway to promote cell survival. In this study, we evaluate the effect of the novel multikinase PIM/PI3K/mTOR inhibitor, AUM302, and commercially available PIM inhibitor, TP-3654. Using five human PDAC cell lines, we found AUM302 to be a potent inhibitor of cell proliferation, cell viability, cell cycle progression, and phosphoprotein expression, while TP-3654 was less effective. Significantly, AUM302 had a strong impact on the viability of gemcitabine-resistant PDAC cells. Taken together, these results demonstrate that AUM302 exhibits antitumor activity in human PDAC cells and thus has the potential to be an effective drug for PDAC therapy.

LncRNAs associated with vascular mimicry establish a novel molecular subtype and prognostic model for pancreatic cancer

BACKGROUND

Vascular mimicry (VM) epitomizes an innovative tumor angiogenesis pathway, potentially serving as an alternate conduit under the assumption of traditional tumor angiogenesis pathway inhibition. The role of VM in pancreatic cancer (PC), however, remains unexplored.

METHODS

Using differential analysis and Spearman correlation, we identified key long non-coding RNAs (lncRNAs) signatures in PC from the collected set of VM-associated genes in the literature. We identified optimal clusters using the non-negative matrix decomposition (NMF) algorithm, and then compared clinicopathological features and prognostic differences between clusters. We also assessed tumor microenvironmental (TME) differences between clusters using multiple algorithms. Using univariate Cox regression analyses as well as lasso regression, we constructed and validated new lncRNA prognostic risk models for PC. We used Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) to analyze model-enriched functions and pathways. Nomograms were then developed to predict patient survival in association with clinicopathological factors. In addition, single-cell RNA-sequencing (scRNA-seq) analysis was used to analyze the expression patterns of VM-related genes and lncRNAs in the PC of TME. Finally, we used the Connectivity Map (cMap) database to predict local anaesthetics that could modify the VM of PC.

RESULTS

In this study, we developed a novel three-cluster molecular subtype using the identified VM-associated lncRNA signatures of PC. The different subtypes have significantly different clinical characteristics and prognostic value, and also show differential treatment response and TME. Following an in-depth analysis, we constructed and validated a novel prognostic risk model for PC based on the VM-associated lncRNA signatures. Enrichment analysis suggested that high riskscores were significantly associated with functions and pathways, including extracellular matrix remodeling, et al. In addition, we predicted eight local anaesthetics that could modulate VM in PC. Finally, we discovered differential expression of VM-related genes and lncRNAs across various cell types within pancreatic cancer.

CONCLUSION

VM has a critical role in PC. This study pioneers the development of a VM-based molecular subtype that demonstrates substantial differentiation in PC populations. Furthermore, we highlighted the significance of VM within the immune microenvironment of PC. Moreover, VM might contribute to PC tumorigenesis through its mediation of mesenchymal remodeling and endothelial transdifferentiation-related pathways, which offers a new perspective on its role in PC.

Co-targeting BCL-XL and BCL-2 by PROTAC 753B eliminates leukemia cells and enhances efficacy of chemotherapy by targeting senescent cells

BCL-XL and BCL-2 are key anti-apoptotic proteins and validated cancer targets. 753B is a novel BCL-XL/BCL-2 proteolysis targeting chimera (PROTAC) that targets both BCL-XL and BCL-2 to the von Hippel-Lindau (VHL) E3 ligase, leading to BCLX L/BCL-2 ubiquitination and degradation selectively in cells expressing VHL. Because platelets lack VHL expression, 753B spares on-target platelet toxicity caused by the first-generation dual BCL-XL/BCL-2 inhibitor navitoclax (ABT-263). Here, we report pre-clinical single-agent activity of 753B against different leukemia subsets. 753B effectively reduced cell viability and induced dose-dependent degradation of BCL-XL and BCL-2 in a subset of hematopoietic cell lines, acute myeloid leukemia (AML) primary samples, and in vivo patient-derived xenograft AML models. We further demonstrated the senolytic activity of 753B, which enhanced the efficacy of chemotherapy by targeting chemotherapy-induced cellular senescence. These results provide a pre-clinical rationale for the utility of 753B in AML therapy, and suggest that 753B could produce an added therapeutic benefit by overcoming cellular senescence-induced chemoresistance when combined with chemotherapy.

m6A eraser FTO impairs gemcitabine resistance in pancreatic cancer through influencing NEDD4 mRNA stability by regulating the PTEN/PI3K/AKT pathway

BACKGROUND

Gemcitabine resistance has brought great challenges to the treatment of pancreatic cancer. The N6-methyladenosine (m6A) mutation has been shown to have a significant regulatory role in chemosensitivity; however, it is not apparent whether gemcitabine resistance can be regulated by fat mass and obesity-associated protein (FTO).

METHODS

Cells with established gemcitabine resistance and tissues from pancreatic cancer patients were used to evaluate FTO expression. The biological mechanisms of the effects of FTO on gemcitabine resistant cells were investigated using CCK-8, colony formation assay, flow cytometry, and inhibitory concentration 50. Immunoprecipitation/mass spectrometry, MeRIP-seq, RNA sequencing and RIP assays, RNA stability, luciferase reporter, and RNA pull down assays were employed to examine the mechanism of FTO affecting gemcitabine resistant pancreatic cancer cells.

RESULTS

The results revealed that FTO was substantially expressed in cells and tissues that were resistant to gemcitabine. Functionally, the gemcitabine resistance of pancreatic cancer could be enhanced by FTO, while its depletion inhibited the growth of gemcitabine resistant tumor cells in vivo. Immunoprecipitation/mass spectrometry showed that the FTO protein can be bound to USP7 and deubiquitinated by USP7, leading to the upregulation of FTO. At the same time, FTO knockdown significantly decreased the expression level of NEDD4 in an m6A-dependent manner. RNA pull down and RNA immunoprecipitation verified YTHDF2 as the reader of NEDD4, which promoted the chemoresistance of gemcitabine resistant cells. FTO knockdown markedly increased the PTEN expression level in an NEDD4-dependent manner and influenced the chemosensitivity to gemcitabine through the PI3K/AKT pathway in pancreatic cancer cells.

CONCLUSION

In conclusion, we found that gemcitabine resistance in pancreatic cancer can be influenced by FTO that demethylates NEDD4 RNA in a m6A-dependent manner, which then influences the PTEN expression level and thereby affects the PI3K/AKT pathway. We also identified that the FTO level can be upregulated by USP7.

The Nanotechnology-Based Approaches against Kirsten Rat Sarcoma-Mutated Cancers

Kirsten rat sarcoma (KRAS) is a small GTPase which acts as a molecular switch to regulate several cell biological processes including cell survival, proliferation, and differentiation. Alterations in KRAS have been found in 25% of all human cancers, with pancreatic cancer (90%), colorectal cancer (45%), and lung cancer (35%) being the types of cancer with the highest mutation rates. KRAS oncogenic mutations are not only responsible for malignant cell transformation and tumor development but also related to poor prognosis, low survival rate, and resistance to chemotherapy. Although different strategies have been developed to specifically target this oncoprotein over the last few decades, almost all of them have failed, relying on the current therapeutic solutions to target proteins involved in the KRAS pathway using chemical or gene therapy. Nanomedicine can certainly bring a solution for the lack of specificity and effectiveness of anti-KRAS therapy. Therefore, nanoparticles of different natures are being developed to improve the therapeutic index of drugs, genetic material, and/or biomolecules and to allow their delivery specifically into the cells of interest. The present work aims to summarize the most recent advances related to the use of nanotechnology for the development of new therapeutic strategies against KRAS-mutated cancers.

Systemic deuteration of SCID mice using the water-isotopologue deuterium oxide (D2 O) inhibits tumor growth in an orthotopic bioluminescent model of human pancreatic ductal adenocarcinoma

Since its initial discovery as a natural isotopologue of dihydrogen oxide (1 H2 O), extensive research has focused on the biophysical, biochemical, and pharmacological effects of deuterated water (2 H2 O [D2 O, also referred to as "heavy water"]). Using a panel of cultured human pancreatic ductal adenocarcinoma (PDAC) cells we have profiled (i) D2 O-induced phenotypic antiproliferative and apoptogenic effects, (ii) redox- and proteotoxicity-directed stress response gene expression, and (iii) phosphoprotein-signaling related to endoplasmic reticulum (ER) and MAP-kinase stress response pathways. Differential array analysis revealed early modulation of stress response gene expression in both BxPC-3 and PANC-1 PDAC cells elicited by D2 O (90%; ≤6 h; upregulated: HMOX1, NOS2, CYP2E1, CRYAB, DDIT3, NFKBIA, PTGS1, SOD2, PTGS2; downregulated: RUNX1, MYC, HSPA8, HSPA1A) confirmed by independent RT-qPCR analysis. Immunoblot-analysis revealed rapid (≤6 h) onset of D2 O-induced MAP-kinase signaling (p-JNK, p-p38) together with ER stress response upregulation (p-eIF2α, ATF4, XBP1s, DDIT3/CHOP). Next, we tested the chemotherapeutic efficacy of D2 O-based drinking water supplementation in an orthotopic PDAC model employing firefly luciferase-expressing BxPC-3-FLuc cells in SCID mice. First, feasibility and time course of systemic deuteration (30% D2 O in drinking water; 21 days) were established using time-resolved whole-body proton magnetic resonance imaging and isotope-ratio mass spectrometry-based plasma (D/H)-analysis. D2 O-supplementation suppressed tumor growth by almost 80% with downregulated expression of PCNA, MYC, RUNX1, and HSP70 while increasing tumor levels of DDIT3/CHOP, HO-1, and p-eIF2α. Taken together, these data demonstrate for the first time that pharmacological induction of systemic deuteration significantly reduces orthotopic tumor burden in a murine PDAC xenograft model.

The combination of gemcitabine and ginsenoside Rh2 enhances the immune function of dendritic cells against pancreatic cancer via the CARD9-BCL10-MALT1 / NF-κB pathway

Cold tumor immune microenvironment (TIME) of pancreatic cancer (PC) with minimal dendritic cell (DC) and T cell infiltration can result in insufficient immunotherapy and chemotherapy. While gemcitabine (GEM) is a first-line chemotherapeutic drug for PC, its efficacy is reduced by immunosuppression and drug resistance. Ginsenoside Rh2 (Rh2) is known to have anti-cancer and immunomodulatory properties. Combining GEM with Rh2 may thus overcome immunosuppression and induce lasting anti-tumor immunity in PC. Here, we showed that after GEM-Rh2 therapy, there was significantly greater tumor infiltration by DCs. Caspase recruitment domain-containing protein 9 (CARD9), a central adaptor protein, was strongly up-regulated DCs with GEM-Rh2 therapy and promoted anti-tumor immune responses by DCs. CARD9 was found to be a critical target for Rh2 to enhance DC function. However, GEM-Rh2 treatment did not achieve the substantial anti-PC efficacy in CARD9^-/- mice as in WT mice. The adoptive transfer of WT DCs to DC-depleted PC mice treated with GEM-Rh2 elicited strong anti-tumor immune responses, although CARD9^-/- DCs were less effective than WT DCs. Our results showed that GEM-Rh2 may reverse cold TIME by enhancing tumor immunogenicity and decreasing the levels of immunosuppressive factors, reactivating DCs via the CARD9-BCL10-MALT1/ NF-κB pathway. Our findings suggest a potentially feasible and safe treatment strategy for PC, with a unique mechanism of action. Thus, Rh2 activation of DCs may remodel the cold TIME and optimize GEM chemotherapy for future therapeutic use.

Co-targeting BCL-XL and MCL-1 with DT2216 and AZD8055 synergistically inhibit small-cell lung cancer growth without causing on-target toxicities in mice

Small-cell lung cancer (SCLC) is an aggressive malignancy with limited therapeutic options. The dismal prognosis in SCLC is in part associated with an upregulation of BCL-2 family anti-apoptotic proteins, including BCL-X_L and MCL-1. Unfortunately, the currently available inhibitors of BCL-2 family anti-apoptotic proteins, except BCL-2 inhibitors, are not clinically relevant because of various on-target toxicities. We, therefore, aimed to develop an effective and safe strategy targeting these anti-apoptotic proteins with DT2216 (our platelet-sparing BCL-X_L degrader) and AZD8055 (an mTOR inhibitor) to avoid associated on-target toxicities while synergistically optimizing tumor response. Through BH3 mimetic screening, we identified a subset of SCLC cell lines that is co-dependent on BCL-X_L and MCL-1. After screening inhibitors of selected tumorigenic pathways, we found that AZD8055 selectively downregulates MCL-1 in SCLC cells and its combination with DT2216 synergistically killed BCL-X_L/MCL-1 co-dependent SCLC cells, but not normal cells. Mechanistically, the combination caused BCL-X_L degradation and suppression of MCL-1 expression, and thus disrupted MCL-1 interaction with BIM leading to an enhanced apoptotic induction. In vivo, the DT2216 + AZD8055 combination significantly inhibited the growth of cell line-derived and patient-derived xenografts and reduced tumor burden accompanied by increased survival in a genetically engineered mouse model of SCLC without causing appreciable thrombocytopenia or other normal tissue injuries. Thus, these preclinical findings lay a strong foundation for future clinical studies to test DT2216 + mTOR inhibitor combinations in a subset of SCLC patients whose tumors are co-driven by BCL-X_L and MCL-1.

State of the art and perspectives in pediatric hepatocellular carcinoma

Hepatoblastoma (HB) and pediatric hepatocellular carcinoma (HCC) are rare primary malignant liver cancers in children and young adults. HB is the most common and accounts for about 70 % cases; it is usually diagnosed during the first 3 years of life. Instead, pediatric HCC is uncommon, and it is associated with a poor prognosis. Overall, the prognosis of pediatric HCC is dismal with 5-year event-free survival of <30 % as compared to >80 % for HB. Surgery approaches, either resection or transplant, remain the best chance for the cure of pediatric HCC. However, chemotherapy can be helpful as an adjuvant or neoadjuvant treatment. International groups have done trials in pediatric HCC with a chemotherapy regimen, based on cisplatin and doxorubicin (PLADO) as for HB, but the efficacy is limited. Sorafenib, a multi-kinase inhibitor, following positive results in adults and in a pilot study in children, is now tested in conjunction with chemotherapy in the PHITT phase III clinical trial. Some studies have been exploring the genetic profiles of patients to find biological hallmarks that determine the aggressiveness of pediatric HCC. Pathways involved in growth and differentiation are dysregulated and as demonstrated in HB and adult HCC, an important role of the Wnt/CTNNB1 pathway in the pathogenesis of pediatric HCC is also emerging. An extended molecular analysis of tumor samples could give information about pathways as possible targets of biological and immunotherapeutic agents bringing new pharmacological options for the treatment of pediatric HCC.

Resistance to the BCL-XL degrader DT2216 in T-cell acute lymphoblastic leukemia is rare and correlates with decreased BCL-XL proteolysis

PURPOSE

The BCL-2 family of anti-apoptotic proteins, BCL-2, BCL-XL and MCL-1, can mediate survival of some types of cancer. DT2216 is a PROteolysis-TArgeting Chimera (PROTAC) that degrades BCL-XL specifically and is in phase 1 trials. We sought to define the frequency and mechanism of resistance to DT2216 in T-cell acute lymphoblastic leukemia (T-ALL) cell lines.

METHODS

We measured cell survival and protein levels of BCL-XL, BCL-2, MCL-1 and the pro-apoptotic BIM in 13 distinct T-ALL cell lines after exposure to varying concentrations of DT2216.

RESULTS

We identified concentrations of DT2216 which were cytotoxic to each T-ALL cell line. These concentrations have no correlation with the initial protein levels of BCL-XL, BCL-2, MCL-1 or BIM in each cell line. However, there was a correlation between survival to DT2216 and the efficiency of degradation of BCL-XL by DT2216. Only one cell line, SUP-T1, had significant resistance to DT2216, defined as an IC50 above what is achievable in murine tumors in vivo.

CONCLUSION

Resistance to DT2216 is rare in a wide variety of T-ALL cells but when it occurs is correlated with decreased BCL-XL degradation. Resistance to DT2216 in T-ALL is not predicted by initial BCL-XL or BIM protein levels, or BCL-2 or MCL-1 levels before or after treatment. These data imply that a phase 2 clinical trial of DT2216 in T-ALL should be widely available and not limited to a subset of patients.

Ten Years of CRISPRing Cancers In Vitro

Cell lines have always constituted a good investigation tool for cancer research, allowing scientists to understand the basic mechanisms underlying the complex network of phenomena peculiar to the transforming path from a healthy to cancerous cell. The introduction of CRISPR in everyday laboratory activity and its relative affordability greatly expanded the bench lab weaponry in the daily attempt to better understand tumor biology with the final aim to mitigate cancer's impact in our lives. In this review, we aim to report how this genome editing technique affected in the in vitro modeling of different aspects of tumor biology, its several declinations, and analyze the advantages and drawbacks of each of them.

Immune senescence in non-small cell lung cancer management: therapeutic relevance, biomarkers, and mitigating approaches

INTRODUCTION

Lung cancer and mainly non-small cell lung cancer (NSCLC) still remain a prevalent malignancy worldwide despite sustained screening approaches. Furthermore, a significant proportion of the cases are diagnosed at advanced stages when conservative therapy is often unsuccessful. Cell senescence is an endogenous antitumor weapon but when it is upregulated exerts opposite activities favoring tumor metastasizing and poor response to therapy. However, little is known about this dangerous relationship between cell senescence and NSCLC outcome or on potential approaches to mitigate its unfavorable consequences.

AREAS COVERED

We discuss cell senescence focusing on immune senescence, its cell and humoral effectors (namely immune senescence associated secretory phenotype-iSASP), its impact on NSCLC outcome, and its biomarkers. Senotherapeutics as mitigating approaches are also considered based on the availability of experimental data pertinent to NSCLC.

EXPERT OPINION

Characterization of NSCLC subsets in which immune senescence is a risk factor for poor prognosis and poor therapeutic response might be very helpful in supporting the addition of senotherapeutics to conventional cancer therapy. This approach has the potential to improve disease outcome but more studies in this area are necessary.

Targeting BCL-XL in fibrolamellar hepatocellular carcinoma

Fibrolamellar hepatocellular carcinoma (FLC) is a rare and often lethal liver cancer with no proven effective systemic therapy. Inhibition of the antiapoptotic protein BCL-XL was found to synergize with a variety of systemic therapies in vitro using cells dissociated from patient-derived xenografts (PDX) of FLC or cells dissociated directly from surgical patient resections. As BCL-XL is physiologically expressed in platelets, prior efforts to leverage this vulnerability in other cancers have been hampered by severe thrombocytopenia. To overcome this toxicity, we treated FLC models with DT2216, a proteolysis targeting chimera (PROTAC) that directs BCL-XL for degradation via the von Hippel-Lindau (VHL) E3 ligase, which is minimally expressed in platelets. The combination of irinotecan and DT2216 in vitro on cells directly acquired from patients or in vivo using several xenografts derived from patients with FLC demonstrated remarkable synergy and at clinically achievable doses not associated with significant thrombocytopenia.

Laminarin Attenuates ROS-Mediated Cell Migration and Invasiveness through Mitochondrial Dysfunction in Pancreatic Cancer Cells

Background: Pancreatic ductal adenocarcinoma (PDAC) is a notoriously aggressive type of cancer with a high metastasis rate. It is conventionally treated by surgical resection and neoadjuvant chemotherapy. However, continuous chemotherapy leads to relapse in most PDAC patients due to chemical resistance. Therefore, novel anticancer agents need to be identified and developed. The antitumor activities of laminarin extracted from brown algae against hepatocarcinoma, lung, and colon cancer have been established. However, its effects on pancreatic cancer have remained obscure. Purpose: Our study identified the anticancer effects of laminarin on pancreatic cancer cells and tried to explain its intracellular mechanisms. Methods: We assessed the cell viability of PANC-1 and MIA PaCa-2 cells using MTT assay. Hanging drop method was used for the spheroid formation. Flow cytometry was conducted to evaluate the several intracellular alterations including apoptosis, ROS production, mitochondrial membrane potential (MMP), and calcium concentration induced by laminarin. An invasion test was performed to assess the inhibitory effect of laminarin on cell migration and the invasive genes were evaluated by RT-qPCR. Signaling pathway related with anticancer effects of laminarin was analyzed by western blot. Results: We report that inhibiting laminarin increased the proliferation and viability of the representative pancreatic cancer cell lines, MIA PaCa-2 and PANC-1. Laminarin triggered apoptosis and mitochondrial impairment as evidenced by depolarized mitochondrial membranes, disrupted calcium, and suppressed cell migration caused by reactive oxygen species production and related intracellular signaling pathways. Moreover, laminarin showed synergistic effects when combined with 5-FU, a standard anticancer agent for PDAC. Conclusion: The present study is the first to report that laminarin exerts anticancer effect through ROS production in pancreatic cancer cells. Laminarin shows potential to serve as a new anticancer agent for treating PDAC.

Selectivity through Targeted Protein Degradation (TPD)

Targeted protein degradation has become a reliable tool in the medicinal chemist's toolbox, as seen with rapid progression of PROTACs (proteolysis targeting chimeras) to clinic. Degraders have unique advantages to target proteins with no functional consequence or scaffolding function to achieve the desired phenotype. In some cases, selectivity was achieved among closely related targets. While the prospective design of degraders to achieve selectivity remains empirical, this Miniperspective analyzes some reported examples to gather key factors that are hypothesized to contribute to selectivity. Ternary complex conformation to access key lysine residues stands out as a potential key contributor. However, protein and E3 ligase expression levels, differential tissue expression, resynthesis rate, ubiquitination rate, and the stability of the ternary complex formed all have the potential to play a significant role. With continued progress in ternary structure determination along with several predictive modeling methods, a rational approach to achieve degradation and selectivity is tantalizingly close.

Targeted protein degraders from an oncologist point of view: The Holy Grail of cancer therapy?

In the era of precision medicine, monoclonal antibodies and small molecule inhibitors are the mainstays of the biological therapy in patients with solid tumors. However, resistance to treatment and the "undruggability" of certain key oncogenic proteins emerged as major limitations and jeopardize the clinical benefit of modern therapeutic approaches. Targeted protein degraders are novel molecules entering the early phase of clinical development that exploit the intracellular ubiquitine-proteasome system to promote a specific degradation of target proteins. Since the peculiar mechanism of action, targeted protein degraders have the potential to limit and overcome resistance to treatment and to allow a full actionability of certain cancer drivers that are actually elusive targets. Here, we discuss the state-of-the-art and the open issues in the development of these emerging biological agents from a clinical perspective and with a focus on solid tumors.