Telomerase Inhibition Research Articles

1,3,4-Oxadiazole as an emerging telomerase inhibitor - a promising anticancer motif

1,3,4-Oxadiazole as an emerging telomerase inhibitor - a promising anticancer motif

A primer extension activating 3D DNAzyme walker for in situ imaging and sensitive detection of telomerase activity.

Acquiring information on telomerase activity at multiple levels contributes to a better understanding of its role in various physiological and pathological processes. Herein, a primer extension activating 3D DNAzyme walker is developed for in situ imaging and sensitive detection of telomerase activity. This walker is constructed via co-modifying specially designed hairpin structured walking strands and track strands on a gold nanoparticle (AuNP). The walking strand contains a pre-blocked DNAzyme sequence and a telomerase primer hybridized to its root. The track strand embeds at an RNA cleavage site and is labeled with the FAM group. After this walker is taken up by cells, the telomerase primer is extended under the action of endogenous telomerase to liberate DNAzyme. The liberated DNAzyme cuts track strands in the presence of the cofactor Mn2+ to drive the walker's processive operation, resulting in an enhanced fluorescence recovery of the AuNP-quenched FAM fluorophore. In situ imaging of telomerase activity in three different cell lines (MCF-7 cells, HeLa cells and HL-7702 cells) was well implemented. The discrimination of cancer cells from normal cells and the screening of telomerase inhibitors have been achieved. The sensitive detection of telomerase activity in HeLa cell lysate has also been realized with a detection limit of 10 cells. This walker performed a new approach for monitoring telomerase activity from different levels, providing a potential tool for clinical diagnosis, prognostic evaluation and drug screening.

Effects of in vitro short- and long-term treatment with telomerase inhibitor in U-251 glioma cells.

The inhibition of the enzyme telomerase (TERT) has been widely investigated as a new pharmacological approach for cancer treatment, but its real potential and the biochemical consequences are not totally understood. Here, we investigated the effects of the telomerase inhibitor MST-312 on a human glioma cell line after both short- and long-term (290 days) treatments. Effects on cell growth, viability, cell cycle, morphology, cell death and genes expression were assessed. We found that short-term treatment promoted cell cycle arrest followed by apoptosis. Importantly, cells with telomerase knock-down revealed that the toxic effects of MST-312 are partially TERT dependent. In contrast, although the long-term treatment decreased cell proliferation at first, it also caused adaptations potentially related to treatment resistance and tumor aggressiveness after long time of exposition. Despite the short-term effects of telomerase inhibition not being due to telomere erosion, they are at least partially related to the enzyme inhibition, which may represent an important strategy to pave the way for tumor growth control, especially through modulation of the non-canonical functions of telomerase. On the other hand, long-term exposure to the inhibitor had the potential to induce cell adaptations with possible negative clinical implications.

Shikonin N-benzyl matrinic acid ester derivatives as novel telomerase inhibitors with potent activity against lung cancer cell lines

In this study, a series of novel shikonin N-benzyl matrinic acid ester derivatives (PMMB-299–PMMB-310) were synthesized and tested for their ability to inhibit the proliferation of cancer cells. Compared with shikonin and matrine, some of the ester derivatives were found to exhibit better anti-proliferative activity against seven different cancer cell lines, with less cytotoxicity toward non-cancerous cells. The strongest anti-proliferative activity was exhibited by PMMB-302, which had an IC50 value of 2.71 μM against A549 cells. The compound caused cell cycle arrest in the G2/M phase and induced apoptosis. Effects on the expression of apoptosis-related molecules such as Bcl2, Bcl-XL, caspase-3, caspase-9 and FADD suggested that PMMB-302 has tumor suppressive roles in lung cancer cells. In addition, PMMB-302 inhibited expression of telomerase core proteins, dyskerin and NHP2, and telomerase reverse transcriptase RNA. Moreover, molecular docking of PMMB-302 was subsequently conducted to determine the probable binding mode with telomerase. Taken together, the results indicate that PMMB-302 acts as a tumor suppressor in lung cancer cells by negatively regulating telomerase expression.

Zinc protoporphyrin binding to telomerase complexes and inhibition of telomerase activity.

Zinc protoporphyrin (ZnPP), a naturally occurring metalloprotoporphyrin (MPP), is currently under development as a chemotherapeutic agent although its mechanism is unclear. When tested against other MPPs, ZnPP was the most effective DNA synthesis and cellular proliferation inhibitor while promoting apoptosis in telomerase positive but not telomerase negative cells. Concurrently, ZnPP down‐regulated telomerase expression and was the best overall inhibitor of telomerase activity in intact cells and cellular extracts with IC50 and EC50 values of ca 2.5 and 6 µM, respectively. The natural fluorescence properties of ZnPP enabled direct imaging in cellular fractions using non‐denaturing agarose gel electrophoresis, western blots, and confocal fluorescence microscopy. ZnPP localized to large cellular complexes (>600 kD) that contained telomerase and dysskerin as confirmed with immunocomplex mobility shift, immunoprecipitation, and immunoblot analyses. Confocal fluorescence studies showed that ZnPP co‐localized with telomerase reverse transcriptase (TERT) and telomeres in the nucleus of synchronized S‐phase cells. ZnPP also co‐localized with TERT in the perinuclear regions of log phase cells but did not co‐localize with telomeres on the ends of metaphase chromosomes, a site known to be devoid of telomerase complexes. Overall, these results suggest that ZnPP does not bind to telomeric sequences per se, but alternatively, interacts with other structural components of the telomerase complex to inhibit telomerase activity. In conclusion, ZnPP actively interferes with telomerase activity in neoplastic cells, thus promoting pro‐apoptotic and anti‐proliferative properties. These data support further development of natural or synthetic protoporphyrins for use as chemotherapeutic agents to augment current treatment protocols for neoplastic disease.

A Randomized Open-Label, Phase 3 Study to Evaluate Imetelstat Versus Best Available Therapy (BAT) in Patients with Intermediate-2 (Int-2) or High-Risk Myelofibrosis (MF) Refractory to Janus Kinase Inhibitor (JAKi)

A Randomized Open-Label, Phase 3 Study to Evaluate Imetelstat Versus Best Available Therapy (BAT) in Patients with Intermediate-2 (Int-2) or High-Risk Myelofibrosis (MF) Refractory to Janus Kinase Inhibitor (JAKi)

On-Target Activity of Imetelstat Correlates with Clinical Benefits, Including Overall Survival (OS), in Heavily Transfused Non-Del(5q) Lower Risk MDS (LR-MDS) Relapsed/Refractory (R/R) to Erythropoiesis Stimulating Agents (ESAs)

On-Target Activity of Imetelstat Correlates with Clinical Benefits, Including Overall Survival (OS), in Heavily Transfused Non-Del(5q) Lower Risk MDS (LR-MDS) Relapsed/Refractory (R/R) to Erythropoiesis Stimulating Agents (ESAs)

Imetelstat Significantly Reduces Leukemia Stem Cells in Patient-Derived Xenograft Models of Pediatric AML

IntroductionAcute myeloid leukemia (AML) is the deadliest malignancy in children. Despite the use of maximally intensive therapy, 20% of patients experience recurrent disease. These patients are also burdened with significant treatment-related toxicities. To improve survival in pediatric AML, novel targeted therapies that are more effective and less toxic are needed. Telomerase inhibition has been shown to be effective in reducing leukemic burden and eradicating leukemia stem cells (LSCs) in syngeneic mouse models of AML and in patient-derived xenograft (PDX) models of adult AML (Bruedigam et al., 2014).Recent transcriptome analyses demonstrate that the genomic landscape of pediatric AML is distinct from adult AML (Bolouri et al., 2018). In fact, mutations in the telomerase complex components are infrequent in pediatric AML unlike adult AML patients (Aalbers et al., 2013). However, similar to what is seen in adult patients, Aalbers et al. identified that telomere lengths in pediatric AML cells were shortened compared to normal leukocytes, and pediatric AML patients with the shortest telomere length tend to have shorter overall survival. Furthermore, the 5-year survival rate was 88% for pediatric AML patients who had lower telomerase activity, and 43% for those patients with higher telomerase activity, suggesting telomerase activity could be an important prognostic factor in pediatric AML patients (Verstovsek et al., 2003).Imetelstat is an oligonucleotide that specifically binds with high affinity to the RNA template of telomerase and is a potent, competitive inhibitor of telomerase enzymatic activity (Asai et al., 2003; Herbert et al., 2005). In this study, we evaluated if imetelstat has anti-leukemia activity in pediatric AML PDX models.ResultsThe PDX lines tested in this study were derived using samples from pediatric AML patients who were 1-14 years old, representing different FAB subtypes. Mouse passaged pediatric AML PDX lines (n=6) were treated ex vivo with imetelstat or mismatch oligo control and the viability of LSC (CD34+CD38low population) was determined at 48 or 96 h by staining with BV785-human CD45, APC-human CD34, Pacific blue-human CD38, FITC conjugated annexin V and propidium iodide (PI). Imetelstat treatment significantly increased apoptosis/death (PI+/annexin V+) of the LSC population in a dose-dependent manner in all PDX lines evaluated (Fig. 1A, B), while it had limited activity on LSCs in normal pediatric bone marrow samples (n=4).The efficacy of imetelstat either alone or in combination with chemotherapy or azacitidine was evaluated in two distinct PDX models of pediatric AML in vivo. Mice engrafted with both NTPL-377 and DF-2 lived longer when treated with imetelstat than the untreated mice (Fig. 1C, D, n=5 each, P<0.05). Mice receiving standard chemotherapy consisting of cytarabine and daunorubicin or azacitidine showed prolonged survival compared to the untreated mice. Interestingly, sequential administration of imetelstat following chemotherapy treatment provided additional benefit over chemotherapy alone (P<0.01). Concurrent treatment of azacitidine and imetelstat further extended survival of these mice compared to azacitidine alone (P<0.05).At the end of the in vivo studies, the percentage of LSC population was evaluated in the bone marrow of mice post euthanasia. There was a significant reduction of LSC population in mice treated with imetelstat compared to those treated with the mismatch oligo (Fig. 1E, F, P<0.05). Neither chemotherapy nor azacitidine alone affected LSC population compared to untreated mice. However, imetelstat significantly reduced the LSC population when combined with chemotherapy or azacitidine compared to single agent (P<0.05). These results were confirmed by secondary transplantation in mice, which showed delayed engraftment of cells isolated from imetelstat treated mice (Fig. 1G, H).ConclusionsImetelstat treatment of pediatric AML PDX samples showed significant dose- and time-dependent effects on the viability of the LSCs to induce cell apoptosis/death. These results were corroborated in vivo in two distinct PDX models which showed reduced LSC population and increased median survival in mice with imetelstat treatment. Combining imetelstat with chemotherapy or azacitidine further enhanced activity against LSCs, suggesting imetelstat could represent an effective therapeutic strategy for pediatric AML. [Display omitted] DisclosuresBarwe: Prelude Therapeutics: Research Funding. Huang: Geron Corp: Current Employment, Current equity holder in publicly-traded company. Gopalakrishnapillai: Geron: Research Funding.

CST does not evict elongating telomerase but prevents initiation by ssDNA binding.

The CST complex (CTC1-STN1-TEN1) has been shown to inhibit telomerase extension of the G-strand of telomeres and facilitate the switch to C-strand synthesis by DNA polymerase alpha-primase (pol α-primase). Recently the structure of human CST was solved by cryo-EM, allowing the design of mutant proteins defective in telomeric ssDNA binding and prompting the reexamination of CST inhibition of telomerase. The previous proposal that human CST inhibits telomerase by sequestration of the DNA primer was tested with a series of DNA-binding mutants of CST and modeled by a competitive binding simulation. The DNA-binding mutants had substantially reduced ability to inhibit telomerase, as predicted from their reduced affinity for telomeric DNA. These results provide strong support for the previous primer sequestration model. We then tested whether addition of CST to an ongoing processive telomerase reaction would terminate DNA extension. Pulse-chase telomerase reactions with addition of either wild-type CST or DNA-binding mutants showed that CST has no detectable ability to terminate ongoing telomerase extension in vitro. The same lack of inhibition was observed with or without pol α-primase bound to CST. These results suggest how the switch from telomerase extension to C-strand synthesis may occur.

Antisense oligonucleotide repress telomerase activity via manipulating alternative splicing or translation

Telomerase is a reverse transcriptase that catalyzes the addition of telomeric repeated DNA onto the 3′ ends of linear chromosomes. Telomerase inhibition was broadly used for cancer therapeutics. Here, six antisense oligonucleotides were designed to regulate TERT mRNA alternative splicing and protein translation. To pursue a better stability in vitro, we chemically modified the oligonucleotides into phosphorothioate (PS) backbone and 2′-O-methoxyethyl (2′-MOE PS) version and phosphoroamidate morpholino oligomer (PMO) version. The oligonucleotides were transfected into HEK 293T cells and HeLa cells, and the mRNA expression, protein level and catalytic activity of telomerase were determined. We found the Int8 notably promoted hTERT mRNA exon 7–8 skipping, which greatly reduced telomerase activity, and the 5′-UTR treatment led to an obvious protein translation barrier and telomerase inhibition. These results demonstrate the potential of antisense oligonucleotide drugs targeting hTERT for antitumor therapy. Moreover, two specific antisense oligonucleotides were identified to be effective in reducing telomerase activity.

PinX1 Depletion Improves Liver Injury in a Mouse Model of Nonalcoholic Fatty Liver Disease via Increasing Telomerase Activity and Inhibiting Apoptosis

PIN2/TRF1-interacting telomerase inhibitor 1 (PinX1) can inhibit tumor growth by inhibiting telomerase activity. However, only few studies investigated the expression and function of PinX1 in nonalcoholic fatty liver disease (NAFLD). Thus, here we aimed to explore the roles of PinX1 in high-fat diet (HFD)-induced NAFLD in mice and in isolated hepatocytes. The mRNA expression of PinX1 and mTERT as well as telomere length were analyzed by RT-PCR. Pathological changes were detected by HE staining and oil red O staining. Triglyceride, cholesterol, alanine aminotransferase, aspartic aminotransferase, and telomerase activity were detected by ELISA. Hepatocyte apoptosis was determined by TUNEL and flow cytometry, and protein expression was analyzed by western blotting. We found that the expression of PinX1 was upregulated in the HFD group compared with the WT group. PinX1 knockout improved HFD-induced liver injury in mice and exhibited less lipid accumulation in hepatocytes. Moreover, telomere length, telomerase activity, and mTERT expression were significantly reduced in liver tissues of HFD-induced mice and palmitic acid-induced hepatocytes, while PinX1 knockout attenuated the effect. Furthermore, HFD-induced PinX1^−/− mice exhibited less hepatocyte apoptosis than HFD-induced WT mice. Besides, PinX1 knockout inhibited the increase of cleaved caspase-3 and cleaved PARP expression in vivo and in vitro. Moreover, inhibition of mTERT reversed the effect of PinX1 knockout in hepatocytes. Taken together, our findings indicate that PinX1 promotes hepatocyte apoptosis and lipid accumulation by decreasing telomere length and telomerase activity in the development of NAFLD. PinX1 might be a target for the treatment of NAFLD.

Coumarins and Gastrointestinal Cancer: A New Therapeutic Option?

Cancers of the gastrointestinal (GI) tract are often life-threatening malignancies, which can be a severe burden to the health care system. Globally, the mortality rate from gastrointestinal tumors has been increasing due to the lack of adequate diagnostic, prognostic, and therapeutic measures to combat these tumors. Coumarin is a natural product with remarkable antitumor activity, and it is widely found in various natural plant sources. Researchers have explored coumarin and its related derivatives to investigate their antitumor activity, and the potential molecular mechanisms involved. These mechanisms include hormone antagonists, alkylating agents, inhibitors of angiogenesis, inhibitors of topoisomerase, inducers of apoptosis, agents with antimitotic activity, telomerase inhibitors, inhibitors of human carbonic anhydrase, as well as other potential mechanisms. Consequently, drug design and discovery scientists and medicinal chemists have collaborated to identify new coumarin-related agents in order to produce more effective antitumor drugs against GI cancers. Herein, we summarize the therapeutic effects of coumarin and its derivatives against GI cancer.

The Effect of Telomerase Inhibition on NK Cell Activity in Acute Myeloid Leukemia.

Purpose: Acute myeloid leukemia (AML) is known to be an invasive and highly lethal hematological malignancy in adults and children. Resistance to the present treatments, including radiotherapy and chemotherapy with their side effects and telomere length shortening are the main cause of the mortality in AML patients. Telomeres sequence which are located at the end of eukaryotic chromosome play pivotal role in genomic stability. Recent studies have shown that apoptosis process is blocked in AML patient by the excessive telomerase activity in cancerous blasts. Therefore, the find of effective ways to prevent disease progression has been considered by the researchers. Natural killer (NK) cells as granular effector cells play a critical role in elimination of abnormal and tumor cells. Given that the cytotoxic function of NK cells is disrupted in the AML patients, we investigated the effect of telomerase inhibitors on NK cell differentiation. Methods: To evaluate telomerase inhibition on NK cell differentiation, the expression of CD105, CD56, CD57, and KIRs was evaluated in CD34+ derived NK cells after incubation of them with BIBR1532. Results: The results showed that the expression of CD105, CD56, CD57, and KIRs receptors reduces after telomerase inhibition. According to these findings, BIBR1532 affected the final differentiation of NK cells. Conclusion: The results revealed that telomerase inhibitor drugs suppress cancer cell progression in a NK cells-independent process.

The Interactions of H2TMPyP, Analogues and Its Metal Complexes with DNA G-Quadruplexes-An Overview.

The evidence that telomerase is overexpressed in almost 90% of human cancers justifies the proposal of this enzyme as a potential target for anticancer drug design. The inhibition of telomerase by quadruplex stabilizing ligands is being considered a useful approach in anticancer drug design proposals. Several aromatic ligands, including porphyrins, were exploited for telomerase inhibition by adduct formation with G-Quadruplex (GQ). 5,10,15,20-Tetrakis(N-methyl-4-pyridinium)porphyrin (H2TMPyP) is one of the most studied porphyrins in this field, and although reported as presenting high affinity to GQ, its poor selectivity for GQ over duplex structures is recognized. To increase the desired selectivity, porphyrin modifications either at the peripheral positions or at the inner core through the coordination with different metals have been handled. Herein, studies involving the interactions of TMPyP and analogs with different DNA sequences able to form GQ and duplex structures using different experimental conditions and approaches are reviewed. Some considerations concerning the structural diversity and recognition modes of G-quadruplexes will be presented first to facilitate the comprehension of the studies reviewed. Additionally, considering the diversity of experimental conditions reported, we decided to complement this review with a screening where the behavior of H2TMPyP and of some of the reviewed metal complexes were evaluated under the same experimental conditions and using the same DNA sequences. In this comparison under unified conditions, we also evaluated, for the first time, the behavior of the AgII complex of H2TMPyP. In general, all derivatives showed good affinity for GQ DNA structures with binding constants in the range of 106–107 M−1 and ligand-GQ stoichiometric ratios of 3:1 and 4:1. A promising pattern of selectivity was also identified for the new AgII derivative.

Advances in myelodysplastic syndrome.

In this review, the focus is on the most recent improvements in diagnosis, prognostication and therapy of myelodysplastic syndromes (MDS) and on their relevance for clinical management. Analytical methods to refine cytogenetic and molecular assessment of MDS have been proposed, improving prognostic stratification obtained from integration of clinical and genomic data. Novel agents with very different mode of action, as single drugs or added to HMA backbone, show promising clinical results in LR-MDS and HR-MDS. Luspatercept has obtained approval given the fact that in transfusion-dependent erythropoietic-stimulating agent resistant/relapsed LR-MDS induced nearly 50% of transfusion independence. Another investigational agent showing efficacy and possibly disease modifying activity in the same setting is the telomerase inhibitor imetelstat. Results from phase II study with azacytidine and pevonedistat indicate the concrete possibility to enhance durable responses compared with azacitidine single drug. In the same direction are the preliminary results of other agents with different mode of action: magrolimab, venetoclax, sabatolimab, as well as the targeted therapy with enasidenib and ivosidenib. New posttransplant maintenance strategies may concur to prolong response. Better diagnosis and prognostic stratification may allow a more precise and personalized treatment of MDS with novel agent combinations leading to improved therapeutic algorithms.

Oligonucleotide-Functionalized Gold Nanoparticles for Synchronous Telomerase Inhibition, Radiosensitization, and Delivery of Theranostic Radionuclides.

Telomerase represents an attractive target in oncology as it is expressed in cancer but not in normal tissues. The oligonucleotide inhibitors of telomerase represent a promising anticancer strategy, although poor cellular uptake can restrict their efficacy. In this study, gold nanoparticles (AuNPs) were used to enhance oligonucleotide uptake. “match” oligonucleotides complementary to the telomerase RNA template subunit (hTR) and “scramble” (control) oligonucleotides were conjugated to diethylenetriamine pentaacetate (DTPA) for 111In-labeling. AuNPs (15.5 nm) were decorated with a monofunctional layer of oligonucleotides (ON–AuNP) or a multifunctional layer of oligonucleotides, PEG(polethylene glycol)800-SH (to reduce AuNP aggregation) and the cell-penetrating peptide Tat (ON–AuNP–Tat). Match–AuNP enhanced the cellular uptake of radiolabeled oligonucleotides while retaining the ability to inhibit telomerase activity. The addition of Tat to AuNPs increased nuclear localization. 111In–Match–AuNP–Tat induced DNA double-strand breaks and caused a dose-dependent reduction in clonogenic survival of telomerase-positive cells but not telomerase-negative cells. hTR inhibition has been reported to sensitize cancer cells to ionizing radiation, and 111In–Match–AuNP–Tat therefore holds promise as a vector for delivery of radionuclides into cancer cells while simultaneously sensitizing them to the effects of the emitted radiation.

SERS-based copper-mediated signal amplification strategy for simple and sensitive detection of telomerase activity

Simple and sensitive detection of telomerase activity is of vital importance for both early diagnosis and therapy of malignant tumors. Inspired by DNA-biobarcode amplification reported by Chad A. Mirkin, we developed a facile DNA-biobarcode-like SERS-based copper-mediated signal amplification strategy for sensitive detection of telomerase activity. In this strategy, a duplex DNA constructed by hybridization of a copper oxide nanoparticle (CuO NP)-labeled reporting sequence (RS) with the telomerase primer sequence (TS) is ingeniously designed, and anchored on the magnetic bead (MB) to build the CuO NPs-encoded magnetic bead (MB-CuO NPs) detection probe. Upon selective sensing of telomerase, telomerase elongation reaction and structure change of TS products make the CuO NP-RS displace and separate from MB. The separated CuO NPs are dissolved into a mass of Cu2+, which prompt monodisperse dopamine-functionalized AgNPs (D-AgNPs) signal probe into aggregation, resulting in color changes and significantly enhancing of SERS signal. The SERS signal increases with the increase of Cu2+, which is directly proportional to the telomerase. Benefiting from the transformation of CuO NP to Cu2+ with a high amplification effect, this strategy could realize the telomerase activity measurement down to 3 HeLa cells and a dynamic range of 10–10000 cells. It shows a significant improvement of sensitivity without need for other enzymes and elaborate design, which escapes from the complicated manipulations and design in polymerase chain reaction (PCR) and DNA amplification techniques. Moreover, with this strategy, telomerase activities of different cell lines and telomerase inhibitors screening were successfully performed. Significantly, it can also be utilized for visual detection of telomerase, which validates the potential on-site application and its application as point-of-care testing (POCT) for efficient monitoring. Given the high-performance for telomerase analysis, the strategy has a promising application in biological detection and clinical diagnosis, as well as point-of-care tests.

Camptothecin shows better promise than Curcumin in the inhibition of the Human Telomerase: A computational study

ObjectivesThe Human Telomerase enzyme has become a drug target in the treatment of cancers and age-related disorders. This study aims to identify potential natural inhibitors of the Human Telomerase from compounds derived from edible African plants. Materials and methodsA library of 1,126 natural compounds was molecularly docked against the Telomerase Reverse Transcriptase (PDB ID: 5ugw), the catalytic subunit of the target protein. Curcumin, a known Telomerase inhibitor was used as the standard. The front-runner compounds were screened for bioavailability, pharmacokinetic properties, and bioactivity using the SWISSADME, PKCSM, and Molinspiration webservers respectively. The molecular dynamic simulation and analyses of the apo and holo proteins were performed by the Galaxy supercomputing webserver. ResultsThe results of the molecular docking and virtual screening reveal Augustamine and Camptothecin as lead compounds. Augustamine has better drug-likeness and pharmacokinetic properties while Camptothecin showed better bioactivity and stronger binding affinity (-8.2 kcal/mol) with the target. The holo structure formed by Camptothecin showed greater inhibitory activity against the target with a total RMSF of 169.853, B-Factor of 20.164, and 108 anti-correlating residues. ConclusionThough they both act at the same binding site, Camptothecin induces greater Telomerase inhibition and better molecular stability than the standard, Curcumin. Further tests are required to investigate the inhibitory activities of the lead compounds.

The Effect and Mechanism of Novel Telomerase Inhibitor Nilo 22 on Leukemia Cells

To investigate the cytotoxic effect and its mechanism of the micromolecule compound on the leukemia cells. The cytotoxic effects of 28 Nilotinib derivatives on K562, KA, KG, HA and 32D cell lines were detected by MTT assays, and the compound Nilo 22 was screen out. Cell apoptosis and cell cycle on leukemia cells were detected by flow cytometry. The effect of compound screened out on leukemogenesis potential of MLL-AF9 leukemia mice GFP+ cells was tested by colony-forming units assays (CFU). The cytotoxic effect was further detected by transplant assays ex vivo. Telomerase activity assay, C-circle assay were used to measure the effects of compound on the length mechanism of telomere, RT-PCR was used to detected the changes of telomere. Nilo 22 serves as the most outstanding candidate out of 28 Nilotinib derivatives, which impairs leukemia cell lines, but spares normal hematopoietic cell line. Comparing with Nilotinib, Nilo 22 could induce the apoptosis of GFP+ cells significantly, slightly arrests the cell cycle at G0/G1 phase, and significantly inhibits colony formation and prolong the progression in MLL-AF9 leukemia mice model. The expression showed that the compound could slow the disease progression in MLL-AF9 leukemia mice significantly. Mechanistically, Nilo 22 could reduce the length of telomere by inhibiting telomerase activity and alternative lengthening of telomere (ALT). Nilo 22 shows a significant cytotoxic effect on mice and human leukemia cells, especially for drug resistance cells. Nilo 22 is a promising anti-leukemia agent to solve the common clinical problems of drug resistance and relapse of leukemia.

High BMI1 Expression with Low CD8+ and CD4+ T Cell Activity Could Promote Breast Cancer Cell Survival: A Machine Learning Approach.

BMI1 is known to play a key role in the regulation of stem cell self-renewal in both endogenous and cancer stem cells. High BMI1 expression has been associated with poor prognosis in a variety of human tumors. The aim of this study was to reveal the correlations of BMI1 with survival rates, genetic alterations, and immune activities, and to validate the results using machine learning. We investigated the survival rates according to BMI1 expression in 389 and 789 breast cancer patients from Kangbuk Samsung Medical Center (KBSMC) and The Cancer Genome Atlas, respectively. We performed gene set enrichment analysis (GSEA) with pathway-based network analysis, investigated the immune response, and performed in vitro drug screening assays. The survival prediction model was evaluated through a gradient boosting machine (GBM) approach incorporating BMI1. High BMI1 expression was correlated with poor survival in patients with breast cancer. In GSEA and in in silico flow cytometry, high BMI1 expression was associated with factors indicating a weak immune response, such as decreased CD8+ T cell and CD4+ T cell counts. In pathway-based network analysis, BMI1 was directly linked to transcriptional regulation and indirectly linked to inflammatory response pathways, etc. The GBM model incorporating BMI1 showed improved prognostic performance compared with the model without BMI1. We identified telomerase inhibitor IX, a drug with potent activity against breast cancer cell lines with high BMI1 expression. We suggest that high BMI1 expression could be a therapeutic target in breast cancer. These results could contribute to the design of future experimental research and drug development programs for breast cancer.