Selective Apoptosis Of Cancer Cells Research Articles

Thio and Seleno-Psoralens as Efficient Triplet Harvesting Photosensitizers for Photodynamic Therapy.

The Psoralen (Pso) molecule finds extensive applications in photo-chemotherapy, courtesy of its triplet state forming ability. Sulfur and selenium replacement of exocyclic carbonyl oxygen of organic chromophores foster efficient triplet harvesting with near unity triplet quantum yield. These triplet-forming photosensitizers are useful in Photodynamic Therapy (PDT) applications for selective apoptosis of cancer cells. In this work, we have critically assessed the effect of the sulfur and selenium substitution at the exocyclic carbonyl (TPso and SePso, respectively) and endocyclic oxygen positions of Psoralen. It resulted in a significant redshifted absorption spectrum to access the PDT therapeutic window with increased oscillator strength. The reduction in singlet-triplet energy gap and enhancement in the spin-orbit coupling values increase the number of intersystem crossing (ISC) pathways to the triplet manifold, which shortens the ISC lifetime from 10-5 s for Pso to 10-8 s for TPso and 10-9 s for SePso. The intramolecular photo-induced electron transfer process, a competitive pathway to ISC, is also considerably curbed by exocyclic functionalizations. In addition, a maximum of 115 GM of two-photon absorption (2PA) with IR absorption (660-1050 nm) confirms that the Psoralen skeleton can be effectively tweaked via single chalcogen atom replacement to design a suitable PDT photosensitizer.

Chitosan-grafted folic acid decorated one-dimensional GONS: A biocompatible drug cargo for targeted co-delivery of anticancer agents

In conventional chemotherapy, the cancer cells can become highly resilient due to a phenomenon known as multi-drug resistance (MDR). The co-delivery of chemotherapeutic agents assisted with novel nanocarrier-based targeted DDS may counter the MDR issues and subsequently improve their therapeutic efficacy. In line with this, the present work deals with the development of 1D graphene oxide nanoscrolls (GONS)-based nano delivery system for co-delivery of chemosensitizer along with the chemotherapeutic agent. Herein, the 1D GONS nanocarrier was initially functionalized with chitosan (CS) biopolymer and folic acid (FA) further to enhance their biocompatibility and target-specific co-delivery. The resultant GONS-CS-FA (GCF) nanocarriers were co-loaded with doxorubicin (DOX) and caffeic acid (CA) at different weight proportions with respect to nanocarrier and drug composition. The optimum loading efficiency of 51.14 ± 1.47 % (DOX) and 49.70 ± 1.19 % (CA) was observed for GCF: drug ratio of 2.5 with drug composition of 1:1. In vitro release at pH 5 yielded ~83 % DOX and 75 % CA, compared to ~71 % DOX and 61 % CA at pH 7.4 over 7 days, suggesting a higher and targeted drug release in the cancer microenvironment. Cytotoxicity tests revealed selective apoptosis in cancer cells (A549) while maintaining cytocompatibility with normal cells (HEK293).

Novel triterpenoid pyrones, phthalimides and phthalates are selectively cytotoxic in CCRF-CEM cancer cells – Synthesis, potency, and mitochondrial mechanism of action

A series of triterpenoid pyrones was synthesized and subsequently modified to introduce phthalimide or phthalate moieties into the triterpenoid skeleton. These compounds underwent in vitro cytotoxicity screening, revealing that a subset of six compounds exhibited potent activity, with IC50 values in the low micromolar range. Further biological evaluations, including Annexin V and propidium iodide staining experiment revealed, that all compounds induce selective apoptosis in cancer cells. Measurements of mitochondrial potential, cell cycle analysis, and the expression of pro- and anti-apoptotic proteins confirmed, that apoptosis was mediated via the mitochondrial pathway. These findings were further supported by cell cycle modulation and DNA/RNA synthesis studies, which indicated a significant increase in cell accumulation in the G0/G1 phase and a marked reduction in S-phase cells, alongside a substantial inhibition of DNA synthesis. The activation of caspase-3 and the cleavage of PARP, coupled with a decrease in the expression of Bcl-2 and Bcl-XL proteins, underscored the induction of apoptosis through the mitochondrial pathway. Given their high activity and pronounced effect on mitochondria function, trifluoromethyl pyrones 1f and 2f, and dihydrophthalimide 2h have been selected for further development.

Intracellular Hyperbranched Polymerization for Circumventing Cancer Drug Resistance.

Polymerization inside living cells provides chemists with a multitude of possibilities to modulate cell activities. Considering the advantages of hyperbranched polymers, such as a large surface area for target sites and multilevel branched structures for resistance to the efflux effect, we reported a hyperbranched polymerization in living cells based on the oxidative polymerization of organotellurides and intracellular redox environment. The intracellular hyperbranched polymerization was triggered by reactive oxygen species (ROS) in the intracellular redox microenvironment, effectively disrupting antioxidant systems in cells by an interaction between Te (+4) and selenoproteins, thus inducing selective apoptosis of cancer cells. Importantly, the obtained hyperbranched polymer aggregated into branched nanostructures in cells, which could effectively evade drug pumps and decrease drug efflux, ensuring the polymerization for persistent treatment. Finally, in vitro and in vivo studies confirmed that our strategy presented selective anticancer efficacy and well biosafety. This approach provides a way for intracellular polymerization with desirable biological applications to regulate cell activities.

Induction of Aryl Hydrocarbon Receptor-Mediated Cancer Cell-Selective Apoptosis in Triple-Negative Breast Cancer Cells by a High-Affinity Benzimidazoisoquinoline.

Triple-negative breast cancer (TNBC) remains a disease with a paucity of targeted treatment opportunities. The aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor that is involved in a wide range of physiological processes, including the sensing of xenobiotics, immune function, development, and differentiation. Different small-molecule AhR ligands drive strikingly varied cellular and organismal responses. In certain cancers, AhR activation by select small molecules induces cell cycle arrest or apoptosis via activation of tumor-suppressive transcriptional programs. AhR is expressed in triple-negative breast cancers, presenting a tractable therapeutic opportunity. Here, we identify a novel ligand of the aryl hydrocarbon receptor that potently and selectively induces cell death in triple-negative breast cancer cells and TNBC stem cells via the AhR. Importantly, we found that this compound, Analog 523, exhibits minimal cytotoxicity against multiple normal human primary cells. Analog 523 represents a high-affinity AhR ligand with potential for future clinical translation as an anticancer agent.

A Phase 1, Open-Label, Dose-Escalation Study of Selinexor Plus Ruxolitinib in Patients with Treatment-Naïve Myelofibrosis

Background: Myelofibrosis (MF) is commonly associated with acquired somatic gene mutations in JAK2, CALR, or MPL. Spleen volume reduction and improvement in symptom burden of MF are attained in 40% of patients treated with the common front-line therapy ruxolitinib (RUX), a JAK1/2 inhibitor. Selinexor (SEL) is an oral Selective Inhibitor of Nuclear Export (SINE) compound that inhibits exportin-1 (XPO1), which leads to nuclear retention and activation of tumor suppressor proteins (e.g., TP53, IkB, p21), reduction in oncoprotein mRNAs (c-Myc, Bcl-2, Bcl-6, cyclin D) and selective apoptosis of cancer cells. Selinexor has received FDA approval for use in patients with multiple myeloma and diffuse large B-cell lymphoma. Preclinical studies demonstrated activity with the combination of SEL plus RUX. In patients with disease refractory to a JAK inhibitor (JAKi), SEL monotherapy had notable clinical activity and a generally manageable safety profile (NCT03627403). Methods: The ongoing multicenter, open-label, Phase 1/2 study (NCT04562389) is evaluating the safety and efficacy of SEL plus RUX in treatment-naïve MF patients. Two dose levels of SEL were evaluated, 40mg and 60mg orally once-weekly (QW) plus RUX twice daily (BID) as per label in 28-day cycles. For nausea prophylaxis, all patients received a 5-HT3 antagonist prior to each dose SEL and then as needed. Primary objectives include safety, maximum tolerated dose (MTD), recommended Phase 2 dose (RP2D), and preliminary efficacy. Secondary objectives include spleen, symptom, and anemia response, and overall survival. Results: As of July 2022, 19 patients have received at least one dose of oral 40mg (n=4) or 60mg (n=15) weekly SEL with RUX twice daily as per standard of care. Median age was 64 years old (range 44-77). Nine patients had primary MF, 7 had post-ET MF, and 3 had post-PV MF. At baseline, two patients had packed red blood cell (PRBC) transfusion-dependent anemia. DIPSS risk category was int-1 (n=6), int-2 (n=9), and high risk (n=4). Of patients evaluable for spleen response, 11/14 achieved spleen volume reduction of ≥35% (SVR35) at week 12 (79%, 95% CI: 49% to 95%) and 6/7 achieved SVR35 at week 24 (86%, 95% CI: 42% to 100%). Eighty-six percent (12/14) (95% CI: 57% to 98%) of patients achieved SVR35 at any time on study. Thirteen patients with available data and who received at least 12 weeks of treatment were evaluated for symptom response; 9/13 (69%, 95% CI: 39% to 91%) had a total symptom score ≥50% reduction by week 12. Eleven out of 17 PRBC transfusion-independent patients (65%) who received at least 8 weeks of therapy maintained stable hemoglobin (Hgb; ± 2g/dL) or improved Hgb levels (>2g/dL increase) at the last follow up. The most common treatment-emergent adverse events (TEAEs) were nausea (11/19, 58%), anemia (8/19, 42%) and vomiting (8/19, 42%). The most common Grade 3 TEAEs were thrombocytopenia and anemia, with only two Grade 4 TEAEs (thrombocytopenia). Conclusions: In this preliminary analysis, the combination of SEL and RUX shows promising clinical activity to date in patients with treatment-naïve myelofibrosis. The combination has been reasonably well-tolerated and with a manageable side effect profile to date.

Substituted dienes prepared from betulinic acid - Synthesis, cytotoxicity, mechanism of action, and pharmacological parameters.

A set of new substituted dienes were synthesized from betulinic acid by its oxidation to 30-oxobetulinic acid followed by the Wittig reaction. Cytotoxicity of all compounds was tested invitro in eight cancer cell lines and two noncancer fibroblasts. Almost all dienes were more cytotoxic than betulinic acid. Compounds 4.22, 4.30, 4.33, 4.39 had IC50 below 5μmol/L; 4.22 and 4.39 were selected for studies of the mechanism of action. Cell cycle analysis revealed an increase in the number of apoptotic cells at 5×IC50 concentration, where activation of irreversible changes leading to cell death can be expected. Both 4.22 and 4.39 led to the accumulation of cells in the G0/G1 phase with partial inhibition of DNA/RNA synthesis at 1×IC50 and almost complete inhibition at 5×IC50. Interestingly, compound 4.39at 5×IC50 caused the accumulation of cells in the S phase. Higher concentrations of tested drugs probably inhibit more off-targets than lower concentrations. Mechanisms disrupting cellular metabolism can induce the accumulation of cells in the S phase. Both compounds 4.22 and 4.39 trigger selective apoptosis in cancer cells via intrinsic pathway, which we have demonstrated by changes in the expression of the crucial apoptosis-related protein. Pharmacological parameters of derivative 4.22 were superior to 4.39, therefore 4.22 was the finally selected candidate for the development of anticancer drug.

Abstract 691: Antibody conjugated to a bispecific RNA molecule targeting RIG-I and PLK1

Abstract Simultaneous access to several targets has become the subject of intense studies in immuno-oncology. In order to benefit from the synergies provided by the activation of different signaling pathways in immunology and the knockdown of proteins involved in cancer cell survival, we established a bispecific approach. The activation of the innate immune response by delivering agonists of pattern-recognition receptors (PRR) such as RIG-I (retinoic acid-inducible I) represents a promising strategy. RIG-I detects short double-stranded RNA molecules ended by a 5'-di/triphosphate moiety (5'ppp-dsRNA). RIG-I activation promotes type I IFN secretion and cancer-cell selective apoptosis. To obtain a bifunctional molecule, the 5'ppp-dsRNA sequence was designed to silence PLK1 (polo-like kinase 1). Suppressing PLK1 expression with small interfering RNAs (siRNA) leads to cell cycle arrest and retards cancer cell growth. This concept of bifunctional RNAs has been validated by using non-targeted systems.1 To enhance this synergy, we conjugated this 5'ppp-siPLK1 to an antibody for a specific delivery to cancerous cells that overexpress erythropoietin-producing hepatocellular receptor A2 (EphA2) at their surface. Upon binding to EphA2 receptor, the antibody is well internalized, thus making it a good vehicle to deliver the bispecific 5'ppp-siPLK1. After EphA2-positive cells treatment, we observed RIG-I specific activation as well as PLK1 depletion. Both effects were correlated with cellular apoptosis and the mode of action was further confirmed with mechanistic and kinetic studies. Finally, while non-modified unconjugated siRNA has a very short half-life in plasma, we observed an increase in stability for the antibody-5'ppp-siPLK1 conjugates. These data suggest that anti-EphA2 receptor antibody could be used to deliver a bispecific RNA molecule.

A frog-derived bionic peptide with discriminative inhibition of tumors based on integrin αvβ3 identification.

Aureins, natural active peptides extracted from skin secretions of Australian bell frogs, have become a research focus due to the antitumor effects caused by lysing cell membranes. However, clinical translation of Aureins is still limited by non-selective toxicity between normal and cancer cells. Herein, by structure-activity relationship analysis and rational linker design, a dual-function fusion peptide RA3 is designed by tactically fusing Aurein peptide A1 with strong anticancer activity, with a tri-peptide with integrin αvβ3-binding ability which was screened in our previous work. Rational design and selection of fusion linkers ensures α-helical conformation and active functions of this novel fusion peptide, inducing effective membrane rupture and selective apoptosis of cancer cells. The integrin binding and tumor recognition ability of the fusion peptide is further validated by fluorescence imaging in cell and mouse models, in comparison with the non-selective A1 peptide. Meanwhile, increased stability and superior therapeutic efficacy are achieved in vivo for the RA3 fusion peptide. Our study highlights that aided by computational simulation technologies, the biomimetic fusion RA3 peptide has been successfully designed, surmounting the poor tumor-selectivity of the natural defensive peptide, serving as a promising therapeutic agent for cancer treatment.

A Machine Learning Approach Identifies a 30-Gene Model That Predicts Sensitivity to Selinexor in Multiple Myeloma

A Machine Learning Approach Identifies a 30-Gene Model That Predicts Sensitivity to Selinexor in Multiple Myeloma

Kinetics of cell death triggered photothermally using folate-conjugated gold nanoparticles and various laser irradiation conditions in cancer cells

Introduction: In this study, we explore in detail cell-specific targeting efficacy of nano-photo-thermal therapy (NPTT) method and the resulting responses that are induced by variable laser intensities and exposure times in cancer cells to induce selective apoptosis. We delineate the synthesis of a high-yielding synthetic F-AuNPs by tailoring the surface of gold nanoparticles with folic acid to enhance cell selectivity and specificity. Materials and Methods: For this purpose, synthesized F-AuNPs treated cells were irradiated with various laser intensities and exposure duration. Both KB cancer cells, as a folate receptor over-expressing cell line, and L929 normal cells, with low level of folate receptors were used. Following various regimes of NPTT, Cytotoxicity was assessed by MTT assay and comparison of induced apoptosis and necrosis in population of cells were depicted by Annexin/PI staining. Results: We report no significant cytotoxicity difference between KB and L929 cell lines at concentrations up to 40 μM of F-AuNPs. Moreover, no significant cell lethality occurred for various laser irradiation conditions. However, in photothermal therapy, the viability of KB and L929 cells was 57% and 83%, respectively. Flow cytometry clearly revealed the kinetics of cell death. The majority of cancer cell death was related to apoptosis (41% apoptosis of 43% overall cell death). Conclusion: Together, these findings confirm that F-AuNPs based NPTT can either induces cell death via apoptosis or necrosis. The main factor determining whether a cell will die due to apoptosis or necrosis on-demand with PTT depends on laser heating level. Our main target must be to only trigger apoptosis during PTT by using suitable irradiation conditions. As a result, folate targeting ability of the F-AuNPs and laser energy threshold to induce selective apoptosis in cancer cells were shown.

E2F1 Is a Biomarker of Selinexor Resistance in Relapsed/Refractory Multiple Myeloma Patients

Selinexor (KPT-330) is a selective inhibitor of nuclear export (SINE) which specifically targets XPO1 (Exportin 1)-mediated nuclear export, leading to increased nuclear retention of major tumor suppressor proteins and inducing selective apoptosis in cancer cells. Several phase I and II clinical trials demonstrate evidence of anti-cancer activity of Selinexor in solid tumors (i.e metastatic prostate cancer (PMID: 29487219), advanced refractory bone or soft tissue sarcoma (PMID: 27458288) and non-small cell lung cancer (PMID: 28647672); as well as, hematological malignancies, including non-Hodgkin lymphoma (PMID: 28468797), acute myeloid leukemia (PMID: 29304833) and multiple myeloma (MM) (PMID: 29381435). In the STORM (Selinexor Treatment of Refractory Myeloma) trial, the combination of Selinexor with dexamethasone in MM patients refractory to bortezomib, carfilzomib, lenalidomide and pomalidomide (quad-refractory), or in addition, to daratumumab (penta-refractory), has shown an overall response rate (ORR) of 21% (Vogl et al, JCO 2018). Our objective is to identify biomarkers for selection of patients at higher likelihood of clinical benefit from Selinexor salvage and understand mechanisms of Selinexor resistance.We therefore analyzed transcriptional differences using RNA sequencing in CD138+ cells from bone marrow aspirates obtained prior to treatment from 32 MM patients enrolled in STORM. The raw data (fastq) was mapped by using the tool STAR and gene-level annotated by featureCounts. Patients were split in two groups based on their progression-free survival (PFS). Differential expression analysis was performed using the tool DESeq2, which enables a more quantitative analysis of comparative RNA-seq data using shrinkage estimators for dispersion and fold change. The results revealed significant up-regulation of 13 genes in patients with PFS < 120 days (n = 21, p < 0.05) versus patients with PFS > 120 days (n=11), including the transcription factor E2F1 and its targets MYBL2, FANCA, GINS3 and SLX4 (Fig. 1).Next, we evaluated the expression of E2F1 in another set of 26 patients from the STORM trial by Affymetrix U133 gene expression microarrays. Data was analyzed using the Signal Space Transformation (SST)-Robust Multi-Chip Analysis (RMA) algorithm. Patients with PFS < 120 days (n = 19) exhibited significant up-regulation of E2F1 (p < 0.05) (Fig. 2).E2F1 is a transcription factor that regulates cell cycle G1/S progression. At rest, E2F1 is complexed with its negative regulator retinoblastoma(RB) protein. Upon phosphorylation of RB by the Cyclin D1-CDK4/6 complex, pRB is inactivated allowing E2F1 to commence transcription of target genes allowing G1/S progression. E2F transcription factors are exported by XPO1 from the nucleus to the cytoplasm. We treated RPMI8226 (IC50=150nM) and MM1S (IC50=25nM) human myeloma cell lines with Selinexor at IC50 and examined nuclear vs cytoplasmic expression of E2F1 after 24 and 48 hours by western blotting. Our results demonstrated nuclear retention of E2F1 following treatment of HMCLs with Selinexor and suggest a model where overexpression of E2F1 overwhelms the nuclear export mechanism and may result in downstream gene programming that confers a proliferative advantage in cells, manifested by rapid progression (<120 days) in patients.Our findings suggest a model where E2F1 expression may be a biomarker of Selinexor resistance. We are currently validating our findings in additional samples from patients with MM treated with Selinexor. [Display omitted] DisclosuresCrochiere:Karyopharm Therapeutics Inc: Employment. Landesman:Karyopharm Therapeutics Inc: Employment. Chari:Adaptive Biotechnology: Membership on an entity's Board of Directors or advisory committees; Array Biopharma: Research Funding; Bristol Myers Squibb: Consultancy; Pharmacyclics: Research Funding; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Takeda: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; The Binding Site: Consultancy; Janssen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Seattle Genetics: Membership on an entity's Board of Directors or advisory committees; Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding. Cho:Janssen: Consultancy; Genentech Inc: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; J & J: Consultancy; Agenus Inc.: Research Funding; F. Hoffmann-La Roche Ltd: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; BMS: Membership on an entity's Board of Directors or advisory committees. Barlogie:Myeloma Health, LLC: Patents & Royalties: : Co-inventor of patents and patent applications related to use of GEP in cancer medicine licensed to Myeloma Health, LLC; European School of Haematology- International Conference on Multiple Myeloma: Other: travel stipend; Millenium: Consultancy, Research Funding; Dana Farber Cancer Institute: Other: travel stipend; International Workshop on Waldenström's Macroglobulinemia: Other: travel stipend; Celgene: Consultancy, Research Funding; Multiple Myeloma Research Foundation: Other: travel stipend; ComtecMed- World Congress on Controversies in Hematology: Other: travel stipend. Jagannath:Multiple Myeloma Research Foundation: Speakers Bureau; Merck: Consultancy; Novartis: Consultancy; Bristol-Myers Squibb: Consultancy; Celgene: Consultancy; Medicom: Speakers Bureau.

Beyond the "Lock and Key" Paradigm: Targeting Lipid Rafts to Induce the Selective Apoptosis of Cancer Cells.

For more than 40 years, the fluid mosaic model of cellular membranes has supported our vision of an inert lipid bilayer containing membrane protein receptors that are randomly hit by extracellular molecules to trigger intracellular signaling events. However, the notion that compartmentalized cholesterol- and sphingomyelin-rich membrane microdomains (known as lipid rafts) spatially arrange receptors and effectors to promote kinetically favorable interactions necessary for the signal transduction sounds much more realistic. Despite their assumed importance for the dynamics of ligand-receptor interactions, lipid rafts and biomembranes as a whole remain less explored than the other classes of biomolecules because of the higher variability and complexity of their membrane phases, which rarely provide the detailed atomic-level structural data in X-ray crystallography assays necessary for molecular modeling studies. The fact that some alkylphospholipids (e.g. edelfosine: 1-O-octadecyl-2-O-methyl-rac-glycero-3-phosphocholine) selectively induce the apoptotic death of cancer cells by recruiting Fas death receptors and the downstream signaling molecules into clusters of lipid rafts suggests these potential drug targets deserve a more in-depth investigation. Herein, we review the structure of lipid rafts, their role in apoptotic signaling pathways and their potential role as drug targets for the treatment of cancer.

Selective apoptosis induction in cancer cells using folate-conjugated gold nanoparticles and controlling the laser irradiation conditions

In this study, we explained in detail a targeted nano-photo-thermal therapy (NPTT) method to induce selective apoptosis in cancer cells. Folate-conjugated gold nanoparticles (F-AuNPs) were synthesized by tailoring the surface of AuNPs with folic acid to enhance the specificity of NPTT. KB cancer cells, as a folate receptor over-expressing cell line, and L929 normal cells with low level of folate receptors were incubated with the synthesized F-AuNPs and then irradiated with various laser intensities and exposure durations. Following various regimes of NPTT, we assessed the level of cell viability and the ratio of apoptosis/necrosis. No significant cytotoxicity was observed for both cell lines at concentrations up to 40 μM of F-AuNPs. Moreover, no significant cell lethality occurred for various laser irradiation conditions. The viability of KB and L929 cells incubated with F-AuNPs (40 μM; 6 h) and then irradiated by laser (1 W/cm2; 2 min) was 57 and 83%, respectively. It was also demonstrated that the majority of cancer cell death is related to apoptosis (41% apoptosis of 43% overall cell death). In this process of F-AuNPs based NPTT, it may be concluded that the main factor determining whether a cell dies due to apoptosis or necrosis depends on laser irradiation conditions. In this study, we explained in detail a targeted nano-photo-thermal therapy (NPTT) method to induce selective apoptosis in cancer cells.

Direct Pharmacological Targeting of a Mitochondrial Ion Channel Selectively Kills Tumor Cells In Vivo

The potassium channel Kv1.3 is highly expressed in the mitochondria of various cancerous cells. Here we show that direct inhibition of Kv1.3 using two mitochondria-targeted inhibitors alters mitochondrial function and leads to reactive oxygen species (ROS)-mediated death of even chemoresistant cells independently of p53 status. These inhibitors killed 98% of exvivo primary chronic B-lymphocytic leukemia tumor cells while sparing healthy B cells. In orthotopic mouse models of melanoma and pancreatic ductal adenocarcinoma, the compounds reduced tumor size by more than 90% and 60%, respectively, while sparing immune and cardiac functions. Our work provides direct evidence that specific pharmacological targeting of a mitochondrial potassium channel can lead to ROS-mediated selective apoptosis of cancer cells invivo, without causing significant side effects.

Abstract 331: Beta-catenin nuclear translocation in colorectal cancer cells is suppressed by PDE10A inhibition, cGMP elevation, and activation of PKG

Abstract Phosphodiesterase 10A (PDE10A) is a cGMP and cAMP degrading PDE isozyme that is highly expressed in the brain striatum where it appears to play an important role in cognition and psychomotor activity. PDE10 inhibitors are being developed for the treatment of schizophrenia and Huntington's disease and are generally well tolerated, possibly because of low expression levels in most peripheral tissues. We recently reported high levels of PDE10 in colon tumors and that genetic silencing of PDE10 by siRNA or inhibition with small molecule inhibitors can suppress colon tumor cell growth with a high degree of selectivity over normal colonocytes (Li et al., Oncogene 2015). These observations suggest PDE10 may have an unrecognized role in tumorigenesis. Here we report that the concentration range by which the highly specific PDE10 inhibitor, Pf-2545920 (MP-10), inhibited colon tumor cell growth parallels the concentration range required to increase cGMP and cAMP levels, and activate PKG and PKA, respectively. Moreover, PDE10 knockdown by shRNA reduced the sensitivity of colon tumor cells to the growth inhibitory activity of Pf-2545920. Pf-2545920 also inhibited the translocation of β-catenin to the nucleus, thereby reducing β-catenin mediated transcription of survivin, which resulted in caspase activation and apoptosis. This was determined to be through a PKG mediated pathway through the use of small molecule inhibitors of PKG and PKA. PDE10 mRNA was also found to be elevated in colon tumors compared with normal tissues in a cDNA array. We also report the increase in PDE10 mRNA in 50% of a small collection of human clinical specimens collected at the Mitchell Cancer Institute (n = 13). In addition, novel PDE10 inhibitor, MCI-030, reduced tumor size and activated PDE10 signaling mechanisms in vivo. These findings suggest that PDE10 can be targeted for cancer therapy or prevention whereby inhibition results in cGMP elevation and PKG activation to reduce β-catenin-mediated transcription of survival proteins leading to the selective apoptosis of cancer cells. Citation Format: Kevin J. Lee, Ashley S. Lindsey, Luciana Madeira da Silva, Alisa Trinh, Bernard Gary, Joel Andrews, Veronica Ramirez-Alcantara, Adam B. Keeton, Wen-Chi Chang, Margie Clapper, Gary A. Piazza. Beta-catenin nuclear translocation in colorectal cancer cells is suppressed by PDE10A inhibition, cGMP elevation, and activation of PKG. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 331.

Benzamide capped peptidomimetics as non-ATP competitive inhibitors of CDK2 using the REPLACE strategy

Inhibition of cyclin dependent kinase 2 (CDK2) in complex with cyclin A in G1/S phase of the cell cycle has been shown to promote selective apoptosis of cancer cells through the E2F1 pathway. An alternative approach to catalytic inhibition is to target the substrate recruitment site also known as the cyclin binding groove (CBG) to generate selective non-ATP competitive inhibitors. The REPLACE strategy has been applied to identify fragment alternatives and substituted benzoic acid derivatives were evaluated as a promising scaffold to present appropriate functionality to mimic key peptide determinants. Fragment Ligated Inhibitory Peptides (FLIPs) are described which potently inhibit both CDK2/cyclin A and CDK4/cyclin D1 and have preliminary anti-tumor activity. A structural rationale for binding was obtained through molecular modeling further demonstrating their potential for further development as next generation non ATP competitive CDK inhibitors.

The non-genomic loss of function of tumor suppressors: an essential role in the pathogenesis of chronic myeloid leukemia chronic phase.

BackgroundChronic Myeloid Leukemia was always referred as a unique cancer due to the apparent independence from tumor suppressors’ deletions/mutations in the early stages of the disease. However, it is now well documented that even genetically wild-type tumor suppressors can be involved in tumorigenesis, when functionally inactivated. In particular, tumor suppressors’ functions can be impaired by subtle variations of protein levels, changes in cellular compartmentalization and post-transcriptional/post-translational modifications, such as phosphorylation, acetylation, ubiquitination and sumoylation. Notably, tumor suppressors inactivation offers challenging therapeutic opportunities. The reactivation of an inactive and genetically wild-type tumor suppressor could indeed promote selective apoptosis of cancer cells without affecting normal cells.Main bodyChronic Myeloid Leukemia (CML) could be considered as the paradigm for non-genomic loss of function of tumor suppressors due to the ability of BCR-ABL to directly promote functionally inactivation of several tumor suppressors.Short conclusionIn this review we will describe new insights on the role of FoxO, PP2A, p27, BLK, PTEN and other tumor suppressors in CML pathogenesis. Finally, we will describe strategies to promote tumor suppressors reactivation in CML.

149. In Vitro-Synthesized Sendai Virus RNA Fragments Induced Antitumor Immunity and Cancer Cell-Selective Apoptosis

Three different clinical trials to treat malignant melanoma, castration-resistant prostate cancer and malignant mesothelioma using inactivated Sendai virus (hemagglutinating virus of Japan; HVJ) particles called HVJ-envelope (HVJ-E) are on-going because of the multiple-anti-cancer activities of HVJ-E. One the activities is the activation of anticancer immunity through inactivation of Treg (regulatory T cell) and promotion of NK cells activation and generation of CTL against cancers by producing interferon (IFN)-β, CXCL10, RANTES and IL-6. Another is the cancer selective apoptosis by induction of proapoptotic genes such as TRAIL and Noxa in various human cancer cells but not in normal cells. Most of these anti-cancer activities are conducted by RNA genome fragments of HVJ-E through RIG-I/MAVS (retinoic-acid inducible gene-I, mitochondrial antiviral signaling protein) signal pathway. Among various Sendai virus strains, Sendai virus Cantell strain showed the highest production of IFN-β in dendritic cells (DCs) and the strongest DC maturaion and we found that DI (defective interfering) particles of Cantell strain resulted in those immunostimulatory activities. Then, we investigated RNA molecules in Cantell HVJ DI particles which have no replication activities. The Cantell stain HVJ DI RNA has complementary termini (approximately 100nt) and exhibits the highest binding affinity to RIG-I. DI RNA genome (544 base) was isolated and transferred to human prostate cancer cell PC3 by lipofection. The DI RNA induced higher expression level of those apoptosis-related proteins such as Noxa and TRAIL and more cancer cell death than whole-genome RNA (approximately 15 kb) of complete Cantell strain without DI particles. Furthermore, we examined whether a specific structure of the DI RNA genome stimulates the RIG-I/MAVS downstream-related cancer suppressive pathways using HVJ-derived in vitro transcribed (IVT) RNAs. IVT-B2 which is derived from Cantell HVJ DI genome has a special secondary structure with a double-stranded RNA terminus and a single-stranded RNA loop. This IVT-B2 strongly stimulated RIG-I dependent proapoptotic proteins induction in prostate cancer cells. Modified IVT-B2 RNAs which had shorter dsRNA stem lost cancer cell killing activity and proapoptotic gene expressions. On the other hand, other modified IVT-RNA which had deleted ssRNA region in loop structure did not induce cancer cell-selective killing. We also found that calf intestinal alkaline-phosphatase-treated IVT-B2 RNA lost capability of inducing RIG-I/MAVS-related downstream Noxa and TRAIL expression. Finally, in vivo electroporation of IVT-B2 RNA induced intra-tumoral apoptosis and tumor suppression in human prostate cancer cell-xenograft mouse model by both direct tumor-cell killing and NK cell activation. These findings provide a novel nucleic acid medicine for the cancer treatment.

An RNA Molecule Derived From Sendai Virus DI Particles Induces Antitumor Immunity and Cancer Cell-selective Apoptosis

Inactivated Sendai virus (hemagglutinating virus of Japan; HVJ) envelope (HVJ-E) induces anticancer immunity and cancer cell-selective apoptosis through the recognition of viral RNA genome fragments by retinoic acid-inducible gene-I (RIG-I). Here, we discovered that the "copy-back" type of defective-interfering (DI) particles that exist in the Cantell strain of HVJ induced the human PC3 prostate cancer cell death more effectively than the Sendai/52 strain or Cantell strain, which contain fewer DI particles. DI particle genomic RNA (~550 bases) activated proapoptotic genes such as Noxa and/or TNF-related apoptosis-inducing ligand (TRAIL) in human prostate cancer cells to induce cancer cell-selective apoptosis. DI particle-derived RNA was synthesized by in vitro transcription (in vitro transcribed (IVT)-B2). IVT-B2 RNA, which has a double-stranded region in its secondary structure, promoted a stronger anticancer effect than IVT-HN RNA, which does not have a double-stranded region in its secondary structure. The intratumoral transfection of IVT-B2 significantly reduced the volume of a human prostate tumor and induced tumor cell apoptosis in the xenograft mouse model. Moreover, the involvement of natural killer (NK) cells in IVT-B2-RNA-induced anticancer effects was also suggested. These findings provide a novel nucleic acid medicine for the treatment of cancer.