Design, synthesis and SARs of novel telomerase inhibitors based on BIBR1532

Discovery of telomerase inhibitors: existing strategies and emerging innovations

Telomerase, crucial for maintaining telomere length, is an attractive target for cancer therapy due to its role in cellular immortality. Despite three decades of research efforts, no small-molecule telomerase inhibitors have been clinically approved, highlighting the extensive challenges in developing effective telomerase-based therapeutics. This review examines conventional and emerging methods to measure telomerase activity and discusses existing inhibitors, including oligonucleotides and small molecules. Furthermore, this review highlights recent breakthroughs in structural studies of telomerase using cryo-electron microscopy, which can facilitate improved structure-based drug design. Altogether, advancements in structural methodologies and high-throughput screening offer promising prospects for telomerase-based cancer therapeutic development.

Lead Optimization of BIBR1591 To Improve Its Telomerase Inhibitory Activity: Design and Synthesis of Novel Four Chemical Series with In Silico, In Vitro, and In Vivo Preclinical Assessments

Herein, modifications to the previously reported BIBR1591 were conducted to obtain bioisosteric candidates with improved activities. The % inhibition of the newly afforded candidates against the telomerase target was investigated. Notably, 6f achieved superior telomerase inhibition (63.14%) compared to BIBR1532 and BIBR1591 (69.64 and 51.58%, respectively). In addition, 8a and 8b showed comparable promising telomerase inhibition with 58.65 and 55.57%, respectively, which were recorded to be frontier to that of BIBR1591. 6f, 8a, and 8b were tested against five cancer cell lines related to the lung and liver subtypes. Moreover, 6f was examined on both cell cycle progression and apoptosis induction in HuH7 cancer cells. Furthermore, the in vivo antitumor activity of 6f was further assessed in female mice with solid Ehrlich carcinoma. In addition, molecular docking and molecular dynamics simulations were carried out. Collectively, 6f, 8a, and 8b could be considered potential new telomerase inhibitors to be subjected to further investigation and/or optimization.

Expedient discovery of novel oxime ester derivatives of piperine/piperine analogs as potent pesticide candidates and their mode of action against Tetranychus cinnabarinus Boisduval

BACKGROUND

Nowadays, pest infestation and resistance have appeared as a consequence of repeated and extensive use of pesticides. Thus, development of new effective pesticide candidates in crop protection is highly desirable. Herein, a series of new piperine derivatives containing oxime ester scaffolds were regioselectively and stereoselectively prepared as pesticidal agents.

RESULTS

Steric configurations of compounds 2, 5z and 13e were definitively determined by single-crystal X-ray diffraction. Against Tetranychus cinnabarinus, notably, compounds 5f [median lethal concentration (LC50 ) = 0.14 mg mL-1 ] and 5v (LC50  = 0.13 mg mL-1 ) showed >107-fold greater acaricidal activity than piperine (LC50  = 15.02 mg mL-1 ), which were comparable to the commercial acaricide spirodiclofen. Against Aphis citricola, compound 5d (LD50  = 19.12 ng aphid-1 ) exhibited 6.1-fold more potent aphicidal activity than piperine (LD50  = 116.06 ng aphid-1 ). Additionally, through scanning electron microscopy, the toxicology study suggested that the acaricidal activity of piperine derivatives may be related to damage of the cuticle layer crest of T. cinnabarinus.

CONCLUSION

The structure-activity relationships suggested that 3,4-dioxymethylene of piperine was crucial for its acaricidal activity; and introduction of a certain length of aliphatic chain at the C-2 position was beneficial to the aphicidal and acaricidal activities. Compounds 5f and 5v are potential leads for further structural modification as acaricidal agents. © 2023 Society of Chemical Industry.

Zeolitic Imidazolate Framework-8 (ZIF-8) as a Drug Delivery Vehicle for the Transport and Release of Telomerase Inhibitor BIBR 1532

Telomerase is constitutively overexpressed in the majority of human cancers and telomerase inhibition provides a promising broad-spectrum anticancer therapeutic strategy. BIBR 1532 is a well-known synthetic telomerase inhibitor that blocks the enzymatic activity of hTERT, the catalytic subunit of telomerase. However, water insolubility of BIBR 1532 leads to low cellular uptake and inadequate delivery and thus, limits its anti-tumor effects. Zeolitic imidazolate framework-8 (ZIF-8) is considered as an attractive drug delivery vehicle for improved transport, release and anti-tumor effects of BIBR 1532. Herein, ZIF-8 and BIBR 1532@ZIF-8 were synthesized, respectively, and the physicochemical characterizations confirmed the successful encapsulation of BIBR 1532 in ZIF-8 coupled with an improved stability of BIBR 1532. ZIF-8 could alter the permeability of lysosomal membrane probably by the imidazole ring-dependent protonation. Moreover, ZIF-8 encapsulation facilitated the cellular uptake and release of BIBR 1532 with more accumulation in the nucleus. BIBR 1532 encapsulation with ZIF-8 triggered a more obvious growth inhibition of cancer cells as compared with free BIBR 1532. A more potent inhibition on hTERT mRNA expression, aggravated G0/G1 arrest accompanied with an increased cellular senescence were detected in BIBR 1532@ZIF-8-treated cancer cells. Our work has provided preliminary information on improving the transport, release and efficacy of water-insoluble small molecule drugs by using ZIF-8 as a delivery vehicle.

Sequential hydrozirconation/Pd-catalyzed cross coupling of acyl chlorides towards conjugated (2E,4E)-dienones

Dienones are challenging building blocks in natural product synthesis due to their high reactivity and complex synthesis. Based on previous work and own initial results, a new stereospecific sequential hydrozirconation/Pd-catalyzed acylation of enynes with acyl chlorides towards conjugated (2E,4E)-dienones is reported. We investigated a number of substrates with different alkyl and aryl substituents in the one-pot reaction and showed that regardless of the substitution pattern, the reactions lead to the stereoselective formation (≥95% (2E,4E)) of the respective dienones under mild conditions. It was found that enynes with alkyl chains gave higher yields than the corresponding aryl-substituted analogues, whereas the variation of the acyl chlorides did not affect the reaction significantly. The synthetic application is demonstrated by formation of non-natural and natural dienone-containing terpenes such as β-ionone which was available in 4 steps and 6% overall yield.

Ligand-Based Design on the Dog-Bone-Shaped BIBR1532 Pharmacophoric Features and Synthesis of Novel Analogues as Promising Telomerase Inhibitors with In Vitro and In Vivo Evaluations

Telomerase is an outstanding biological target for cancer treatment. BIBR1532 is a non-nucleoside selective telomerase inhibitor; however, it experiences ineligible pharmacokinetics. Herein, we aimed to design new BIBR1532-based analogues as promising telomerase inhibitors. Therefore, two novel series of pyridazine-linked to cyclopenta[b]thiophene (8a-f) and tetrahydro-1-benzothiophene (9a-f) were synthesized. A quantitative real-time polymerase chain reaction was utilized to investigate the telomerase inhibitory activity of candidates. Notably, 8e and 9e exhibited the best inhibition profiles. Moreover, 8e showed strong antitumor effects against both MCF-7 and A549 cancer cell lines. The effects of 8e on the cell cycle and apoptosis were measured. Besides, 8e was evaluated for its in vivo antitumor activity using solid Ehrlich carcinoma. The reduction in both the tumor weight and volume was greater than doxorubicin. Also, molecular docking and ADME studies were performed. Finally, a SAR study was conducted to gain further insights into the different telomerase inhibition potentials upon variable structural modifications.

New Genetic Bomb Trigger: Design, Synthesis, Molecular Dynamics Simulation, and Biological Evaluation of Novel BIBR1532-Related Analogs Targeting Telomerase against Non-Small Cell Lung Cancer

Telomeres serve a critical function in cell replication and proliferation at every stage of the cell cycle. Telomerase is a ribonucleoprotein, responsible for maintaining the telomere length and chromosomal integrity of frequently dividing cells. Although it is silenced in most human somatic cells, telomere restoration occurs in cancer cells because of telomerase activation or alternative telomere lengthening. The telomerase enzyme is a universal anticancer target that is expressed in 85–95% of cancers. BIBR1532 is a selective non-nucleoside potent telomerase inhibitor that acts by direct noncompetitive inhibition. Relying on its structural features, three different series were designed, and 30 novel compounds were synthesized and biologically evaluated as telomerase inhibitors using a telomeric repeat amplification protocol (TRAP) assay. Target compounds 29a, 36b, and 39b reported the greatest inhibitory effect on telomerase enzyme with IC₅₀ values of 1.7, 0.3, and 2.0 μM, respectively, while BIBR1532 displayed IC₅₀ = 0.2 μM. Compounds 29a, 36b, and 39b were subsequently tested using a living-cell TRAP assay and were able to penetrate the cell membrane and inhibit telomerase inside living cancer cells. Compound 36b was tested for cytotoxicity against 60 cancer cell lines using the NCI (USA) procedure, and the % growth was minimally impacted, indicating telomerase enzyme selectivity. To investigate the interaction of compound 36b with the telomerase allosteric binding site, molecular docking and molecular dynamics simulations were used.

Pharmacological preconditioning by TERT inhibitor BIBR1532 confers neuronal ischemic tolerance through TERT-mediated transcriptional reprogramming

After a sublethal ischemic preconditioning (IPC) stimulus, the brain has a remarkable capability of acquiring tolerance to subsequent ischemic insult by establishing precautionary self-protective mechanism. Understanding this endogenous mechanism would reveal novel and effective neuroprotective targets for ischemic brain injury. Our previous study has implied that telomerase reverse transcriptase (TERT) is associated with IPC-induced tolerance. Here, we investigated the mechanism of TERT-mediated ischemic tolerance. Preconditioning was modeled by oxygen-glucose deprivation (OGD) and by TERT inhibitor BIBR1532 in primary neurons. We found that ischemic tolerance was conferred by BIBR1532 preconditioning. We used the Cleavage-Under-Targets-And-Tagmentation approach, a recently developed method with superior signal-to-noise ratio, to comprehensively map the genomic binding sites of TERT in primary neurons, and showed that more than 50% of TERT-binding sites were located at the promoter regions. Mechanistically, we demonstrated that under normal conditions TERT physically bound to many previously unknown genomic loci in neurons, whereas BIBR1532 preconditioning significantly altered TERT-chromatin-binding profile. Intriguingly, we found that BIBR1532-preconditioned neurons showed significant up-regulation of promoter binding of TERT to the mitochondrial anti-oxidant genes, which were correlated with their elevated expression. Functional analysis further indicated that BIBR1532-preconditioning significantly reduced ROS levels and enhanced tolerance to severe ischemia-induced mitochondrial oxidative stress in neurons in a TERT-dependent manner. Together, these results demonstrate that BIBR1532 confers neuronal ischemic tolerance through TERT-mediated transcriptional reprogramming for up-regulation of mitochondrial anti-oxidation gene expression, suggesting the translational potential of BIBR1532 as a therapeutic agent for the treatment of cerebral ischemic injury and oxidative stress-induced neurological disorders.

Telomere length: biological marker of cellular vitality, aging, and health-disease process

The aging process occurs due to the decline of vital physiological functions and adaptability of the body, being influenced by genetics and lifestyle. With advances in genetics, biological aging can be calculated by telomere length. Telomeres are regions at the ends of chromosomes that play a role in the maintenance and integrity of DNA. With biological aging, telomere shortening occurs, causing cellular senescence. Several studies show that shorter telomeres are associated with acute and chronic diseases, stress, addictions, and intoxications. Even in the current COVID-19 pandemic, telomere shortening is proposed as a marker of severity in individuals infected by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). On the other hand, healthy lifestyle habits increase telomere length and balance of various cellular functions, preventing diseases.

Recent trends in cancer therapy: A review on the current state of gene delivery

Cancer treatment has been always considered one of the most critical and vital themes of clinical issues. Many approaches have been developed, depending on the type and the stage of tumor. Gene therapy has the potential to revolutionize different cancer therapy. With the advent of recent bioinformatics technologies and genetic science, it become possible to identify, diagnose and determine the potential treatment using the technology of gene delivery. Several approaches have been developed and experimented in vitro and vivo for cancer therapy including: naked nucleic acids based therapy, targeting micro RNAs, oncolytic virotherapy, suicide gene based therapy, targeting telomerase, cell mediated gene therapy, and CRISPR/Cas9 based therapy. In this review, we present a straightforward introduction to cancer biology and occurrence, highlighting different viral and non-viral gene delivery systems for gene therapy and critically discussed the current and various strategies for cancer gene therapy.