The antiretroviral agent saquinavir enhances hTERT expression and telomerase activity in human T leukaemia cells in vitro

Inhibition of human DNA alkylation damage repair enzyme ALKBH2 by HIV protease inhibitor ritonavir

The human DNA repair enzyme AlkB homologue-2 (ALKBH2) repairs methyl adducts from genomic DNA and is overexpressed in several cancers. However, there are no known inhibitors available for this crucial DNA repair enzyme. The aim of this study was to examine whether the first-generation HIV protease inhibitors having strong anti-cancer activity can be repurposed as inhibitors of ALKBH2. We selected four such inhibitors and performed in vitro binding analysis against ALKBH2 based on alterations of its intrinsic tryptophan fluorescence and differential scanning fluorimetry. The effect of these HIV protease inhibitors on the DNA repair activity of ALKBH2 was also evaluated. Interestingly, we observed that one of the inhibitors, ritonavir, could inhibit ALKBH2-mediated DNA repair significantly via competitive inhibition and sensitized cancer cells to alkylating agent methylmethane sulfonate (MMS). This work may provide new insights into the possibilities of utilizing HIV protease inhibitor ritonavir as a DNA repair antagonist.

Pharmacoinformatic screening of phytoconstituent and evaluation of its anti-PDAC effect using in vitro studies

With no prominent treatment for pancreatic ductal adenocarcinoma (PDAC) in conventional chemotherapy, recent studies have focused on uniting conventional and traditional medicines including plant phytoconstituents. Herein, we used pharmacoinformatic studies to identify potent phytoconstituent as ligand having inhibition activities against canonical anticancer targets, and evaluated its effect on PDAC cell lines. SwissTargetPrediction and SuperPred tools were utilized to segregate protein targets of ligand in humans, following which FunRich was applied to garner its targets in PDAC. STRING analysis predicted protein-protein interactions and dynamic simulation studies confirmed stability of ligand-protein complex. For in vitro cytotoxic potential, ligand treatment at different concentrations was given to PDAC cell lines both alone and combined with gemcitabine, followed by evaluation of effects on migration. Differential gene expression was checked using PCR for evaluating mechanism of cytotoxicity. Results showed pentagalloylglucose (PGG) with highest docking and MMGBSA scores for Cyclooxygenase 2 (Cox2) inhibition site. SwissTargetPrediction and SuperPred analysis detected 40 targets of PGG in PDAC. Simulation data showed stability of protein-ligand complex. In in vitro experiments Mia-PaCa-2 was more sensitive to PGG than Panc-1. PGG successfully inhibited migration both alone and in combination with gemcitabine. Additionally, PGG treatment induced apoptosis in both the cell lines; but showed antagonism when combined with gemcitabine. In conclusion, our report demonstrates PGG has good binding with Cox2 and showed anti-PDAC activity by inhibiting migration and inducing apoptosis, thus it can be used as a therapy option. But further studies are required to confirm its behaviour as a combination therapy drug.Communicated by Ramaswamy H. Sarma.

Melatonin inhibits MLL-rearranged leukemia via RBFOX3/hTERT and NF-κB/COX-2 signaling pathways

MLL-rearranged leukemia is an aggressive malignancy associated with poor outcome, which is refractory to conventional treatment. Melatonin has been proven to exert anti-tumor activity, but the effect of melatonin on MLL-r leukemia and the underlying mechanism remain poorly understood. In this study, melatonin inhibited cell proliferation and induced apoptosis by activating the caspase-dependent apoptotic pathway in MLL-r leukemia cells. Mechanistic investigations revealed that melatonin suppressed the expression of hTERT by abrogating the binding activity of RBFOX3 to the hTERT promoter. Melatonin also blocked NF-κB nuclear translocation and suppressed NF-κB binding to the COX-2 promoter, thereby suppressing the expression of COX-2. In addition, clinical samples revealed that melatonin exerts anti-leukemic activity in primary MLL-r leukemia blasts ex vivo. In vivo, the mice treated with melatonin experienced a larger reduction in leukemic burden than the control group in a MLL-r leukemia xenograft mouse model. Collectively, these results suggest that melatonin inhibits MLL-rearranged leukemia through suppressing the RBFOX3/hTERT and NF-κB/COX-2 signaling pathways. Our findings provide new insights into the role of melatonin for MLL-r leukemia treatment.

Beneficial and Detrimental Effects of Antiretroviral Therapy on HIV-Associated Immunosenescence

Since the introduction of highly active antiretroviral therapy more than 2 decades ago, HIV-related deaths have dramatically decreased and HIV infection has become a chronic disease. Due to the inability of antiretroviral drugs to eradicate the virus, treatment of HIV infection requires a systemic lifelong therapy. However, even when successfully treated, HIV patients still show increased incidence of age-associated co-morbidities compared with uninfected individuals. Virus- induced immunosenescence, a process characterized by a progressive decline of immune system function, contributes to the premature ageing observed in HIV patients. Although antiretroviral therapy has significantly improved both the quality and length of patient lives, the life expectancy of treated patients is still shorter compared with that of uninfected individuals. In particular, while antiretroviral therapy can contrast some features of HIV-associated immunosenescence, several anti-HIV agents may themselves contribute to other aspects of immune ageing. Moreover, older HIV patients tend to have a worse immunological response to the antiviral therapy. In this review we will examine the available evidence on the role of antiretroviral therapy in the control of the main features regulating immunosenescence.

Brief Report: Differential Effects of Tenofovir, Abacavir, Emtricitabine, and Darunavir on Telomerase Activity In Vitro

In vitro, tenofovir and abacavir induced a significant dose-dependent inhibition of telomerase activity at therapeutic concentrations in peripheral blood mononuclear cells of healthy subjects. Median inhibition of telomerase activity by tenofovir at 0.5 and 1 μM was 29% [Interquartile range (IQR) 29%-34%, P = 0.042] and 28% (IQR 28%-41%, P = 0.042), respectively. Abacavir inhibition was 12% (IQR 9%-13%, P = 0.043) at 3 μM and 14% (IQR 10%-29%, P = 0.043) at 10 μM. Tenofovir and abacavir did not change human telomerase reverse transcriptase (hTERT) levels or mRNA levels of other telomerase complex genes. Exposure to emtricitabine or darunavir did not affect telomerase activity, hTERT protein levels, or mRNA levels of telomerase/shelterin genes.

HIV-protease inhibitors for the treatment of cancer: Repositioning HIV protease inhibitors while developing more potent NO-hybridized derivatives?

The possible use of HIV protease inhibitors (HIV-PI) as new therapeutic option for the treatment of cancer primarily originated from their success in treating HIV-related Kaposi's sarcoma (KS). While these findings were initially attributed to immune reconstitution and better control of oncogenic viral infections, the number of reports on solid tumors, KS, lymphoma, fibrosarcoma, multiple myeloma and prostate cancer suggest other mechanisms for the anti-neoplastic activity of PIs. However, a major drawback for the possible adoption of HIV-PIs in the therapy of cancer relies on their relatively weak anticancer potency and important side effects. This has propelled several groups to generate derivatives of HIV-PIs for anticancer use, through modifications such as attachment of different moieties, ligands and transporters, including saquinavir-loaded folic acid conjugated nanoparticles and nitric oxide (NO) derivatives of HIV-PIs. In this article, we discuss the current preclinical and clinical evidences for the potential use of HIV-PIs, and of novel derivatives, such as saquinavir-NO in the treatment of cancer.

Transcription Regulation of the Human Telomerase Reverse Transcriptase (hTERT) Gene

Embryonic stem cells and induced pluripotent stem cells have the ability to maintain their telomere length via expression of an enzymatic complex called telomerase. Similarly, more than 85%–90% of cancer cells are found to upregulate the expression of telomerase, conferring them with the potential to proliferate indefinitely. Telomerase Reverse Transcriptase (TERT), the catalytic subunit of telomerase holoenzyme, is the rate-limiting factor in reconstituting telomerase activity in vivo. To date, the expression and function of the human Telomerase Reverse Transcriptase (hTERT) gene are known to be regulated at various molecular levels (including genetic, mRNA, protein and subcellular localization) by a number of diverse factors. Among these means of regulation, transcription modulation is the most important, as evident in its tight regulation in cancer cell survival as well as pluripotent stem cell maintenance and differentiation. Here, we discuss how hTERT gene transcription is regulated, mainly focusing on the contribution of trans-acting factors such as transcription factors and epigenetic modifiers, as well as genetic alterations in hTERT proximal promoter.

Synthetic Bax-Anti Bcl2 combination module actuated by super artificial hTERT promoter selectively inhibits malignant phenotypes of bladder cancer

BACKGROUND

The synthetic biology technology which enhances the specificity and efficacy of treatment is a novel try in biomedical therapy during recent years. A high frequency of somatic mutations was shown in the human telomerase reverse transcriptase (hTERT) promoter in bladder cancer, indicating that a mutational hTERT promoter might be a tumor-specific element for bladder cancer therapy. In our study, we aimed to construct a synthetic combination module driven by a super artificial hTERT promoter and to investigate its influence on the malignant phenotypes of bladder cancer.

METHODS

The dual luciferase assay system was used to verify the driven efficiency and tumor-specificity of the artificial hTERT promoter and to confirm the relationship between ETS-1 and the driven efficiency of the artificial hTERT promoter. CCK-8 assay and MTT assay were used to test the effects of the Bax-Anti Bcl2 combination module driven by the artificial hTERT promoter on cell proliferation. Simultaneously, the cell apoptosis was detected by the caspase 3ELISA assay and the flow cytometry analysis after transfection. The results of CCK-8 assay and MTT assay were analyzed by ANOVA. The independent samples t-test was used to analyze other data.

RESULTS

We demonstrated that the artificial hTERT promoter had a higher driven efficiency which might be regulated by transcription factor ETS-1 in bladder cancer cells, compared with wild-type hTERT promoter. Meanwhile, the artificial hTERT promoter showed a strong tumor-specific effect. The cell proliferation inhibition and apoptosis induction were observed in artificial hTERT promoter- Bax-Anti Bcl2 combination module -transfected bladder cancer 5637 and T24 cells, but not in the module -transfected normal human fibroblasts.

CONCLUSION

This module offers us a useful synthetic biology platform to inhibit the malignant phenotypes of bladder cancer in a more specific and effective way.

Pim-1 acts as an oncogene in human salivary gland adenoid cystic carcinoma

Background

Pim-1 (Provirus integration site for Moloney murine leukemia virus 1) belongs to the Ser/Thr kinase family and plays a pivotal role in occurrence and development of oncogenesis. Recent studies have demonstrated that Pim-1 phosphorylates RUNX3 and alters its subcellular localization. However, few studies have concerned the implications of Pim-1 in the salivary gland adenoid cystic carcinoma (ACC). In this study, we aimed to clarify the function of Pim-1 in ACC in vitro. Meanwhile, we measured the levels of Pim-1 and RUNX3 in the ACC tissues. The correlations between Pim-1/RUNX3 levels and clinical parameters were also analyzed.

Methods

SACC-83 and SACC-LM cells were transfected with the Pim-1 siRNA. Pim-1 mRNA and protein expression were measured using real-time PCR and immnuoblot, respectively. Cell proliferation was analyzed by CCK-8 assay. Cell cycle, apoptosis, and mitochondrial membrane potential were detected by flow cytometry. Effects of Pim-1 on cells’ invasion were evaluated by transwell migration assay. Pim-1 and RUNX3 levels in ACC tissues were examined by immunohistochemistry.

Results

Pim-1 siRNA reduces cell proliferation, induces apoptosis, causes cell cycle arrest through cell cycle related proteins (Cyclin D1 and CDK4), mitochondrial depolarization, and decreases invasive ability in SACC-83 and SACC-LM cells. Pim-1 and RUNX3 levels are significantly relevant and associated with T-stage and nerve invasion in the ACC tissues.

Conclusions

This study demonstrates the oncogenic role of Pim-1 in ACC. The findings also suggest that Pim-1 may serve as a neoteric therapeutic target and potential prognostic marker for ACC cancer.

The prognostic value of elevated ezrin in patients with osteosarcoma

Published studies researching the prognostic significance of ezrin expression in patients with osteosarcoma are inconclusive and heterogeneous. We conducted a meta-analysis to assess its prognostic value more precisely. The hazard ratios with corresponding 95 % confidence intervals were calculated to evaluate the effects. Five studies with 318 osteosarcoma patients were included to estimate the relationship between ezrin and disease-free survival, and ezrin and overall survival. Compared with osteosarcoma patients with low or negative ezrin expression, patients with high ezrin expression tended to be associated with lower disease-free survival, but the difference was not significant. However, patients with high ezrin expression were obviously associated with lower overall survival. Therefore, the findings from this systematic review suggest that ezrin expression is an effective biomarker of prognosis in patients with osteosarcoma.