Potent Telomerase Inhibitor Research Articles

Abstract 4485: Identification of novel lead compounds and repurposing FDA approved drugs as telomerase inhibitors using structure-based drug designing approach and their evaluation using in-vitro and ex-vivo assays

Abstract Introduction: Upregulated telomerase activity is an established hallmark in about 85-90% of cancer malignancies making it an attractive therapeutic target. However, the development of approved small-molecule telomerase inhibitors has been impeded by a lack of structural ambiguity for decades. In our study, we have employed a molecular dynamics approach to validate the binding site of BIBR1532, an approved telomerase inhibitor in the hTERT thumb domain followed by a structure-based drug designing approach to repurpose FDA-approved drugs and identify novel lead compounds targeting the enzyme. Material and Methods: Due to the unavailability of a co-crystalized structure of BIBR1532 with the catalytic hTERT thumb domain, we employed a Molecular dynamics-based method to identify and validate the exact binding site of the inhibitor. Two pharmacophore models were generated for the putative and newly identified binding pockets which were screened virtually through an anti-cancer library and Drug Bank database. The models were validated on the basis of the fit value of the BIBR1532 and selectivity value indicating the favorable feature set required. The top hits obtained were filtered using drug-likeliness parameters like Lipinski, ADME, and TOPKAT followed by redocking into their binding site. Finally, lead molecules that were able to dock in the new pocket were validated using Molecular Dynamics (MD)simulation studies and their binding free energy was calculated using MM-PBSA calculations followed by their evaluation using in-vitro TRAP assay. Results: Structural investigation, molecular docking studies, and confirmatory molecular dynamics revealed that the exact binding site of BIBR1532 is 8.4 Å away from the reported FVYL pocket strikingly with clinically relevant and characteristic interactions conserved. We have identified five lead compounds and four lead compounds from DrugBank and the anti-cancer library respectively, that were stable in the new binding pocket based on their MD trajectory analysis, and parameters like RMSD, RMSF, H-bonds and Radius of Gyration as well as their MM-PBSA scores. The lead compounds are being evaluated in vitro using TRAP assay and ex-vivo assays. Conclusion: The study identified five existing FDA-approved drugs in the market for other diseases as potential telomerase inhibitors alongside four novel compounds that can be used for the treatment of cancer in the future after further validation studies. Citation Format: Divpreet Kaur, Madhu Chopra, Daman Saluja. Identification of novel lead compounds and repurposing FDA approved drugs as telomerase inhibitors using structure-based drug designing approach and their evaluation using in-vitro and ex-vivo assays [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4485.

Synthesis, characterization, anti-cancer evaluation, and DNA-binding study of new bay-substituted perylene derivatives

Two new perylene derivatives 1,7-di(3,5-diamino-pyrimidoxyl) perylene-3,4,9,10- tetracarboxylic acid bisanhydride (4) and 1,7-di(2-[3-[(4-amino-2-methylpyrimidin-5-yl)methyl]-4-methyl-1,3-thiazol-3-ium-5-yl]) ethoxyperylene-3,4,9,10-tetracarboxylic bisanhydride (6) have been synthesized. We aimed to study their interactions with G-quadruplex (G4) structures as potent G4 ligands and telomerase inhibitors. We used a PCR-amplified guanine-rich region from the human beta-globin gene, oligonucleotide from human telomeres (a-coreTT), an oncogene (c-kit), and SK-HEP-1 adenocarcinoma cells to characterize those compounds’ binding and stabilizing abilities to G4 structures and anti-cancer potential. All results obtained through UV-visible and fluorescence spectroscopies, agarose gel electrophoresis, and MTT assay on SK-HEP-1 adenocarcinoma cells were in good agreement. Compounds 4 and 6 are promising DNA-binding and cytotoxic compounds with a relatively antiproliferative effect on the selected tumour. In all studies, the formal positive charge carrier, compound 6, showed higher activity in terms of anti-cancer effects. These results may help elucidate the feasibility of the perylene derivatives as future chemo-therapeutic agents.

Limitations of radiosensitization by direct telomerase inhibition to treat high-risk medulloblastoma.

Medulloblastoma (MB) is the most common malignant pediatric brain tumor. Previous studies have elucidated the genomic landscape of MB leading to the recognition of four core molecular subgroups (WNT, SHH, group 3 and group 4) with distinct clinical outcomes. Group 3 has the worst prognosis of all MB. Radiotherapy (RT) remains a major component in the treatment of poor prognosis MB but is rarely curative alone and is associated with acute and long-term toxicities. A hallmark of cancer cells is their unlimited proliferative potential which correlates closely with telomere length. The vast majority of malignant tumors activate telomerase to maintain telomere length, whereas this activity is barely detectable in most normal human somatic tissues, making telomerase inhibition a rational therapeutic target in the setting of cancer recurrence and therapy resistance. We and others have previously shown that short telomeres confer sensitivity to ionizing radiation (IR) suggesting that telomerase inhibition mediated telomere shortening will improve the efficacy of RT while minimizing its side effects. Here, we investigated the efficacy of the combination of IR with IMT, a potent telomerase inhibitor, in an in vivo model of group 3 MB. Our results indicate that although IMT inhibited MB telomerase activity resulting in telomere shortening and delayed tumor growth, the combination with IR did not prevent tumor recurrence and did not improve survival compared to the treatment with IR alone. Together, these findings suggest that the radiosensitization by direct telomerase inhibition is not an effective approach to treat high-risk pediatric brain tumors.

Telomerase Inhibition by MST-312 Sensitizes Breast Cancer Cells to the Anti-cancer Properties of Plumbagin.

Breast cancer is the most common cause of malignancy and the second most common cause of death due to cancer in women. This heterogeneous disease is currently broadly classified as estrogen receptor (ER), progesterone receptor (PR) positive luminal tumors, human epidermal growth factor receptor 2 (HER2) amplified tumors and triple-negative breast cancers (TNBC). Phytochemicals are proven to be promising anti-cancer chemotherapeutics agents with minimal cytotoxic effects on normal cells. Plumbagin (5-hydroxy-2-methyl-1, 4-naphthoquinone) is a phytochemical derived from the roots of Plumbago zeylanica and it is known to possess anti-cancer properties similar to other compounds of naphthoquinones. In about 90% of cancer cells, the telomerase enzyme activity is revived to add telomeric repeats to evade apoptosis. In this study, a combinatorial approach of combining the anti-cancer compound plumbagin to induce genotoxicity and a potent telomerase inhibitor, MST-312 (synthetic derivative of tea catechins), was used to determine the combinational treatment-induced lethality in breast cancer cells such as MDA-MB-231 (TNBC) and MCF-7 (lumina) cells. MDA-MB-231 cells were responsive to combination treatment in both short-term (48 h) and long-term treatment (14 days) in a synergistic manner, whereas in MCF-7, the combination treatment was more effective in the long-term regimen. Furthermore, the cytotoxic effects of the plumbagin and MST-312 combination treatment were not recoverable after the short-term treatment. In conclusion, a combination treatment of MST-312 and plumbagin is proven to be more effective than a single plumbagin compound treatment in inducing DNA damage and telomere dysfunction leading to greater genome instability, cell cycle arrest and eventually cell death in cancer cells.

Anticancer activity, hTERT expression and telomere length analysis in SH-SY5Y neuroblastoma cell lines applied to docetaxel

Neuroblastoma is the most common extracranial solid tumor of infancy in a broad range of clinical courses, ranging from spontaneous regression to fatal progression. Telomere maintenance plays an important role in genome stability and cell proliferation. Telomerase reverse transcriptase (hTERT in humans) is a catalytic subunit of the enzyme telomerase. In this study, it was aimed to determine the anticancer activity of the docetaxel chemotherapeutic agent in neuroblastoma cell line (SH-SY5Y) and to investigate its effect on hTERT gene expression level and telomere length. Molecular docking studies were performed on docetaxel with the crystal structure of telomerase. The electronic properties of docetaxel were calculated using the density functional theory (DFT) method. SH-SY5Y cells were treated for 24, 48 and 72 h with specific concentrations of docetaxel drug ranging from 1 to 100 µg/ml. IC50 doses of docetaxel were determined and administered to SH-SY5Y cells, followed by RNA isolation. hTERT and MYC gene expression levels and telomere length were measured in the docetaxel-treated sample using the RT-PCR method. In addition, theoretical analyzes were made. The IC50 values of docetaxel after 24, 48 and 72 h were 8.32±1.45 μg/ml, 7.67±2.56 μg/ml and 5.51±1.24 μg/ml, respectively. According to the results obtained, docetaxel was found to have the highest activity in 72 h of incubation. It was determined that the docetaxel drug decreased the expression level of the hTERT gene in SH-SY5Y cells. Telomere lengths were significantly reduced in the docetaxel treated SH-SY5Y cell line compared to the control group (p < 0.05). Molecular docking analysis results were in agreement with the experiments. Analysis results indicated a good interaction between docetaxel and the active site of telomerase. The results of this study, reinforced by molecular docking analyzes, might be proved valuable for the development of potent telomerase inhibitors.

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.

Characterization of In Vitro G-Quadruplex Formation of Imetelstat Telomerase Inhibitor

Imetelstat (GRN163L) is a potent and specific telomerase inhibitor currently in clinical development for the treatment of hematological malignancies such as myelofibrosis and myelodysplastic syndrome. It is a 13-mer N3'-P5' thio-phosphoramidate oligonucleotide covalently functionalized at the 5'-end with a palmitoyl lipid moiety through an aminoglycerol linker. As a competitive inhibitor of human telomerase, imetelstat directly binds to the telomerase RNA component sequence (hTR) in the catalytic site of the enzyme and acts as a direct competitor of human telomere binding. Administration of imetelstat causes progressive shortening of the telomeres, thereby inhibiting malignant cells' proliferation. We report here the ability of imetelstat to form stable, parallel, intermolecular G-quadruplex structures in vitro. The impact of the ionic environment on the formation and stability of imetelstat higher-order structure was investigated through circular dichroism spectroscopy, thermal denaturation analysis, and size-exclusion chromatography. We demonstrated that different structural elements, such as the 5'-palmitoyl linker and the thio-phosphoramidate backbone, critically contribute to G-quadruplex stability. Experiments further showed that G-quadruplex formation does not hamper binding to the hTR oligonucleotide sequence in vitro.

The Small Molecule BIBR1532 Exerts Potential Anti-cancer Activities in Preclinical Models of Feline Oral Squamous Cell Carcinoma Through Inhibition of Telomerase Activity and Down-Regulation of TERT.

Expression of telomerase reverse transcriptase (TERT) and telomerase activity (TA) is a main feature of cancer, contributing to cell immortalization by causing telomeres dysfunction. BIBR1532 is a potent telomerase inhibitor that showed potential anti-tumor activities in several types of cancer, by triggering replicative senescence and apoptosis. In a previous work, we detected, for the first time, TERT expression and TA in preclinical models of feline oral squamous cell carcinoma (FOSCC); therefore, we aimed at extending our investigation by testing the effects of treatment with BIBR1532, in order to explore the role of telomerase in this tumor and foreshadow the possibility of it being considered as a future therapeutic target. In the present study, treatment of FOSCC cell lines SCCF1, SCCF2, and SCCF3 with BIBR1532 resulted in successful inhibition of TA, with subsequent cell growth stoppage and decrease in cell viability. Molecular data showed that up-regulation of cell cycle inhibitor p21, unbalancing of Bax/Bcl-2 ratio, and down-regulation of survival gene Survivin were mostly involved in the observed cellular events. Moreover, BIBR1532 diminished the expression of TERT and its transcriptional activator cMyc, resulting in the down-regulation of epidermal growth factor receptor (EGFR), phospho-ERK/ERK ratio, and matrix metalloproteinases (MMPs)-1/-2 and−9, likely as a consequence of an impairment of TERT extra-telomeric functions. Taken together, our data suggest that BIBR1532 exerts multiple anti-cancer activities in FOSCC by inhibiting telomerase pathway and interfering with signaling routes involved in cell proliferation, cell survival, and invasion, paving the way for future translational studies aimed at evaluating its possible employment in the treatment of this severe tumor of cats.

Molecular modelling of quinoline derivatives as telomerase inhibitors through 3D-QSAR, molecular dynamics simulation, and molecular docking techniques

Rising mortality due to cancer has led to the development and identification of newer targets and molecules to cure the disease. Telomerase is one of the attractive targets for design of many chemotherapeutic drugs. This research highlights the designing of novel telomerase inhibitors using ligand-based (3D-QSAR) and structure-based (molecular docking and molecular dynamics simulation) approaches. For the development of the 3D-QSAR model, 37 synthetic molecules reported earlier as telomerase inhibitors were selected from diversified literature. Three different alignment methods were explored; among them, distill alignment was found to be the best method with good statistical results and was used for the generation of QSAR model. Statistically significant CoMSIA model with a correlation coefficient (r2ncv) value of 0.974, leave one out (q2) value of 0.662 and predicted correlation coefficient (r2pred) value of 0.560 was used for the analysis of QSAR. For the MDS study, A-chain of telomerase was stabilised for 50 ns with respect to 1-atm pressure, with an average temperature of 299.98 k and with potential energy of 1,145,336 kJ/m converged in 997 steps. Furthermore, the behaviour study of variants towards the target revealed that active variable gave better affinity without affecting amino acid sequences and dimensions of protein which was accomplished through RMSD, RMSF and Rg analysis. Results of molecular docking study supported the outcomes of QSAR contour maps as ligand showed similar interactions with surrounded amino acids which were identified in contour map analysis. The results of the comprehensive study might be proved valuable for the development of potent telomerase inhibitors.

Investigation on Quantitative Structure-Activity Relationships of 1,3,4-Oxadiazole Derivatives as Potential Telomerase Inhibitors

Telomerase, a reverse transcriptase, maintains telomere and chromosomes integrity of dividing cells, while it is inactivated in most somatic cells. In tumor cells, telomerase is highly activated, and works in order to maintain the length of telomeres causing immortality, hence it could be considered as a potential marker to tumorigenesis.A series of 1,3,4-oxadiazole derivatives showed significant broad-spectrum anticancer activity against different cell lines, and demonstrated telomerase inhibition. This series of 24 N-benzylidene-2-((5-(pyridine-4-yl)-1,3,4-oxadiazol-2yl)thio)acetohydrazide derivatives as telomerase inhibitors has been considered to carry out QSAR studies. The endpoint to build QSAR models is determined by the IC50 values for telomerase inhibition, i.e., the concentration (μM) of inhibitor that produces 50% inhibition. These values were converted to pIC50 (- log IC50) values. We used the most common and transparent method, where models are described by clearly expressed mathematical equations: Multiple Linear Regression (MLR) by Ordinary Least Squares (OLS). Validated models with high correlation coefficients were developed. The Multiple Linear Regression (MLR) models, by Ordinary Least Squares (OLS), showed good robustness and predictive capability, according to the Multi-Criteria Decision Making (MCDM = 0.8352), a technique that simultaneously enhances the performances of a certain number of criteria. The descriptors selected for the models, such as electrotopological state (E-state) descriptors, and extended topochemical atom (ETA) descriptors, showed the relevant chemical information contributing to the activity of these compounds. The results obtained in this study make sure about the identification of potential hits as prospective telomerase inhibitors.

Investigation of Boldine as a Potential Telomerase Inhibitor by Downregulation of hTERT/hTERC in HCT 116 Human Colon Carcinoma Cells

Investigation of Boldine as a Potential Telomerase Inhibitor by Downregulation of hTERT/hTERC in HCT 116 Human Colon Carcinoma Cells

Design, Synthesis and Molecular Docking Analysis of Flavonoid Derivatives as Potential Telomerase Inhibitors

Based on the structural scaffolds of natural products, two series of flavonoid derivatives, for a total of twelve compounds, were designed and synthesized as potential human telomerase inhibitors. Using a modified TRAP-PCR assay, compound 5c exhibited the most potent inhibitory activity against human telomerase with an IC50 value of less than 50 μM. In vitro, the results demonstrated that compound 5c had potent anticancer activity against five classes of tumor cell lines. The molecular docking and molecular dynamics analyses binding to the human telomerase holoenzyme were performed to elucidate the binding mode of active compound 5c. This finding helps the rational design of more potent telomerase inhibitors based on the structural scaffolds of natural products.

Thiazole orange – Spermine conjugate: A potent human telomerase inhibitor comparable to BRACO-19

In this report, we synthesized a series of TO conjugates containing different amino side chains and investigated their binding to telomeric G-quadruplex DNA (G4) using several biophysical methods including fluorometric titration and thermal denaturation monitored by fluorescence and circular dichroism. The composition of side chains strongly affects the binding of these molecules to G-quadruplex DNA. Incorporation of amino side chains increases the binding affinity of TO toward G4 but has a minimal effect on its selectivity for G4 over duplex DNA. The plausible binding modes are a synergistic effect of end-stacking and groove interactions as indicated by docking studies. Inhibition of human telomerase activity by TO derivatives was determined in vitro by the TRAP assay. Several derivatives can selectively inhibit the activity of telomerase over DNA polymerase at low concentrations. More significantly, TO-spermine conjugate (16) exhibits a remarkable effect on telomerase inhibition in the submicromolar range, which is comparable to the inhibition effect of a well-known G4 ligand, BRACO-19. Our results here provide guidance of utilizing TO derivatives as a viable scaffold to design novel G4 ligands, G4 probes, and potent telomerase inhibitors.

Contributory role of microRNAs in anti-cancer effects of small molecule inhibitor of telomerase (BIBR1532) on acute promyelocytic leukemia cell line

Telomerase-mediated immortalization and proliferation of tumor cells is a promising anti-cancer treatment strategy and development of potent telomerase inhibitors is believed to open new window of treatments in human malignancies. In the present study, we found that BIBR1532, a small molecule inhibitor of human telomerase, exerted cytotoxic effects on a panel of human cancer cells spanning from solid tumors to hematologic malignancies; however, as compared with solid tumors, leukemic cells were more sensitive to this inhibitor. This was independent of molecular status of p53 in the leukemic cells. The results of a miRNA PCR array revealed that BIBR1532-induced cytotoxic effects in NB4, the most sensitive cell line, was coupled with alteration in a substantial number of cancer-related miRNAs. Interestingly, most of these miRNAs were found to act as tumor suppressors with validated targets in cell cycle or nuclear factor (NF)-κB–mediated apoptosis. In accordance with a bioinformatics analysis, our experimental studies showed that BIBR1532-induced apoptosis is mediated, at least partly, by inhibition of NF-κB. Moreover, we found that the alteration in the expression of miRNAs was coupled with the alteration in the cell cycle progression. To sum up with, a straightforward interpretation of our results is that telomerase inhibition using BIBR1532 not only induced CDKN1A-mediated G1 arrest in NB4, but also resulted in a caspase-3-dependent apoptotic cell death mostly through suppression of NF-κB axis.

Two telomerase-targeting Pt(ii) complexes of jatrorrhizine and berberine derivatives induce apoptosis in human bladder tumor cells.

Two novel Pt(ii) complexes, [Pt(B-TFA)Cl]Cl (Pt1) and [Pt(J-TFA)Cl]Cl (Pt2) with jatrorrhizine and berberine derivatives (B-TFA and J-TFA) were first prepared as desirable luminescent agents for cellular applications and potent telomerase inhibitors, which can induce bladder T-24 tumor cell apoptosis by targeting telomerase, together with induction of mitochondrial dysfunction, telomere DNA damage and cell-cycle arrest. Importantly, T-24 tumor inhibition rate (TIR) was 50.4% for Pt2, which was higher than that of Pt1 (26.4%) and cisplatin (37.1%). Taken together, all the results indicated that jatrorrhizine and berberine derivatives Pt1 and Pt2 show low toxicity and could be novel Pt-based anti-cancer drug candidates.

Binding of anticancer drug daunomycin to parallel G-quadruplex DNA [d-(TTGGGGT)]4 leads to thermal stabilization: A multispectroscopic investigation

Guanine rich DNA sequences form four stranded G-quadruplex structures found in telomeric DNA and oncogene promoters. Small molecules binding and stabilizing the G-quadruplex disrupt telomere maintenance and gene regulation, thereby limiting the proliferation of cancer cells. The anti-cancer drug daunomycin binds to both G-quadruplex DNA and duplex DNA. We have undertaken a study of interaction of daunomycin to [d-(TTGGGGT)]4 comprising telomeric DNA sequence from Tetrahymena thermophilia to understand the mechanisms of its action. Absorbance, fluorescence and circular dicroism spectra show significant change on interaction with no change in wavelength maxima. The daunomycin dimers present in free state in solution are disrupted on binding. Presence of all sequential short inter proton distance contacts in nuclear magnetic resonance spectra confirm external binding. The observed inter molecular nuclear Overhauser enhancements, changes in chemical shift and molecular docking studies establish well defined binding of daunomycin at two different sites of G-quadruplex DNA. Thermal stabilization of [d-(TTGGGGT)]4 by 10–15 °C upon daunomycin binding is expected to reduce access of telomerase to its functional site at telomeres. The present studies on mode of action pave the way for alternate derivatives/analogues by chemical modification of anthracyclines to arrive at a more potent telomerase inhibitor.

Molecular Recognition of Parallel G-quadruplex [d-(TTGGGGT)]₄ Containing Tetrahymena Telomeric DNA Sequence by Anticancer Drug Daunomycin: NMR-Based Structure and Thermal Stability.

The anticancer drug daunomycin exerts its influence by multiple strategies of action to interfere with gene functioning. Besides inhibiting DNA/RNA synthesis and topoisomerase-II, it affects the functional pathway of telomere maintenance by the telomerase enzyme. We present evidence of the binding of daunomycin to parallel-stranded tetramolecular [d-(TTGGGGT)]4 guanine (G)-quadruplex DNA comprising telomeric DNA from Tetrahymena thermophilia by surface plasmon resonance and Diffusion Ordered SpectroscopY (DOSY). Circular Dichroism (CD) spectra show the disruption of daunomycin dimers, suggesting the end-stacking and groove-binding of the daunomycin monomer. Proton and phosphorus-31 Nuclear Magnetic Resonance (NMR) spectroscopy show a sequence-specific interaction and a clear proof of absence of intercalation of the daunomycin chromophore between base quartets or stacking between G-quadruplexes. Restrained molecular dynamics simulations using observed short interproton distance contacts depict interaction at the molecular level. The interactions involving ring A and daunosamine protons, the stacking of an aromatic ring of daunomycin with a terminal G6 quartet by displacing the T7 base, and external groove-binding close to the T1–T2 bases lead to the thermal stabilization of 15 °C, which is likely to inhibit the association of telomerase with telomeres. The findings have implications in the structure-based designing of anthracycline drugs as potent telomerase inhibitors.

Pin2/TRF1‑binding proteinX1 inhibits colorectal cancer cell migration and invasion invitro and metastasis invivo via the nuclear factor‑κB signaling pathway.

Pin2/TRF1‑binding proteinX1 (PinX1) functioned as a potent inhibitor of telomerase, which was also widely considered to be a sufficient tumor suppressor. Previous studies have demonstrated that PinX1 expression was reduced in several types of cancer and was associated with poor overall survival. However, little is known regarding the role of PinX1 in colorectal cancer (CRC). The present study investigated PinX1 expression via immunostaining of CRC tissue microarrays consisting of tumor and adjacent non‑cancerous tissues (ANCT) from 568 patients. PinX1 expression was significantly lower in CRC tissues than in ANCT. Decreased PinX1 expression was revealed to be associated with lymph node metastasis, distant metastasis and advanced Tumor‑Node‑Metastasis stage, as well as a poorer overall and disease‑free survival. Furthermore, Cox regression analysis determined that a decreased PinX1 expression was an independent prognostic marker for patients with CRC. In an invitro assay, PinX1 markedly restricted CRC cell migration and invasion. Additionally, the present study revealed that PinX1 could hinder the activity of matrix metalloproteinase 2 (MMP2) through nuclear factor (NF)‑κB‑dependent transcription to further suppress the migration and invasion ability of CRC cells through western blot analysis and a gelatin zymography assay. Invivo studies verified that PinX1 could suppress CRC metastasis, as well as the expression of MMP2 and NF‑κB p65. These results suggested that PinX1 can serve as an independent prognostic factor for patients with CRC and that it may function as a tumor metastasis suppressor in the progression of CRC though negatively regulating the NF‑κB/MMP2 signaling pathway.

Blood Telomere Length Changes After Ritonavir-Boosted Darunavir Combined With Raltegravir or Tenofovir-Emtricitabine in Antiretroviral-Naive Adults Infected With HIV-1

Tenofovir is a potent inhibitor of human telomerase. The clinical relevance of this inhibition is unknown. NEAT001/ANRS143 is a randomized trial that showed noninferiority over 96 weeks of ritonavir-boosted darunavir plus raltegravir versus tenofovir disoproxil fumarate/emtricitabine in 805 antiretroviral antiretrovrial-naive HIV-infected adults. We compared changes in whole-blood telomere length measured with quantitative polymerase chain reaction in 201 randomly selected participants (104 raltegravir and 97 tenofovir disoproxil fumarate/emtricitabine). We performed multivariable estimative and predictive linear regression. At week 96, participants receiving tenofovir disoproxil fumarate/emtricitabine had a statistically significant higher gain in telomere length than participants receiving raltegravir. Difference in mean telomere length change between groups (tenofovir disoproxil fumarate/emtricitabine minus raltegravir) from baseline to week 96 adjusted by baseline telomere length was 0.031 (P = .009). This difference was not significantly confounded by age, gender, known duration of HIV infection, CD4 (baseline/nadir), CD8 cells, CD4/CD8 ratio, HIV viral load (baseline/week 96), tobacco and alcohol consumption, statins, or hepatitis C. Antiretroviral-naive HIV-infected adults receiving ritonavir-boosted darunavir and tenofovir disoproxil fumarate/emtricitabine had a significant higher gain in blood telomere length than those receiving ritonavir-boosted darunavir and raltegravir, suggesting a better initial recovery from HIV-associated immunosenescence.

Impact of Nucleos(t)ide Reverse Transcriptase Inhibitors on Blood Telomere Length Changes in a Prospective Cohort of Aviremic HIV-Infected Adults.

Tenofovir is a potent inhibitor of human telomerase. The clinical relevance of this inhibition is unknown. A prospective cohort of human immunodeficiency virus (HIV)-infected participants with suppressed virological replication was recruited to compare whole-blood telomere length (measured by quantitative multiplex polymerase chain reaction analysis) in participants with current exposure to tenofovir disoproxil fumarate (TDF) to that in participants never exposed to TDF. A total of 172 participants were included: 67 were in the TDF group, and 105 were in the non-TDF group (75 were receiving 2 nucleosides [of whom 69 were receiving abacavir], 25 were receiving a nucleos[t]ide reverse transcriptase inhibitor [N{t}RTI]-sparing regimen, and 5 were receiving lamivudine as the only nucleoside). After 2 years, the mean blood telomere length increased significantly in the whole cohort. The TDF group had significantly smaller gains in telomere length than the non-TDF group. In the analysis restricted to participants receiving N(t)RTIs, TDF exposure was not associated with an independent negative effect. In the non-TDF group, participants treated with 2 nucleosides also had significantly smaller gains in telomere length than those receiving N(t)RTI-sparing regimens or lamivudine as the only nucleoside. In HIV-infected adults with prolonged virological suppression, treatment with TDF or abacavir was associated with smaller gains in blood telomere length after 2 years of follow-up.