Camptothecin induces c-Myc- and Sp1-mediated hTERT expression in LNCaP cells: Involvement of reactive oxygen species and PI3K/Akt

Understanding Cancer's Defense against Topoisomerase-Active Drugs: A Comprehensive Review

In recent years, the emergence of cancer drug resistance has been one of the crucial tumor hallmarks that are supported by the level of genetic heterogeneity and complexities at cellular levels. Oxidative stress, immune evasion, metabolic reprogramming, overexpression of ABC transporters, and stemness are among the several key contributing molecular and cellular response mechanisms. Topo-active drugs, e.g., doxorubicin and topotecan, are clinically active and are utilized extensively against a wide variety of human tumors and often result in the development of resistance and failure to therapy. Thus, there is an urgent need for an incremental and comprehensive understanding of mechanisms of cancer drug resistance specifically in the context of topo-active drugs. This review delves into the intricate mechanistic aspects of these intracellular and extracellular topo-active drug resistance mechanisms and explores the use of potential combinatorial approaches by utilizing various topo-active drugs and inhibitors of pathways involved in drug resistance. We believe that this review will help guide basic scientists, pre-clinicians, clinicians, and policymakers toward holistic and interdisciplinary strategies that transcend resistance, renewing optimism in the ongoing battle against cancer.

Natural Products as Anticancer Agents: Current Status and Future Perspectives

Natural products have been an invaluable and useful source of anticancer agents over the years. Several compounds have been synthesized from natural products by modifying their structures or by using naturally occurring compounds as building blocks in the synthesis of these compounds for various purposes in different fields, such as biology, medicine, and engineering. Multiple modern and costly treatments have been applied to combat cancer and limit its lethality, but the results are not significantly refreshing. Natural products, which are a significant source of new therapeutic drugs, are currently being investigated as potential cytotoxic agents and have shown a positive trend in preclinical research and have prompted numerous innovative strategies in order to combat cancer and expedite the clinical research. Natural products are becoming increasingly important for drug discovery due to their high molecular diversity and novel biofunctionality. Furthermore, natural products can provide superior efficacy and safety due to their unique molecular properties. The objective of the current review is to provide an overview of the emergence of natural products for the treatment and prevention of cancer, such as chemosensitizers, immunotherapeutics, combinatorial therapies with other anticancer drugs, novel formulations of natural products, and the molecular mechanisms underlying their anticancer properties.

Human Telomerase Reverse Transcriptase as a Therapeutic Target of Dihydroartemisinin for Esophageal Squamous Cancer

Objective: To elucidate the oncogenic role of human telomerase reverse transcriptase (hTERT) in esophageal squamous cancer and unravel the therapeutic role and molecular mechanism of dihydroartemisinin (DHA) by targeting hTERT. Methods: The expression of hTERT in esophageal squamous cancer and the patients prognosis were analyzed by bioinformatic analysis from TCGA database, and further validated with esophageal squamous cancer tissues in our cohort. The Cell Counting Kit-8 (CCK8) and colony formation assay were used to evaluate the proliferation of esophageal squamous cancer cell lines (Eca109, KYSE150, and TE1) after hTERT overexpression or treated with indicated concentrations of DHA. Transwell migration assay and scratch assay were employed to determine the migration abilities of cancer cells. Fluorescence microscopy and flow cytometry were conducted to measure the intracellular reactive oxygen species (ROS) levels in cancer cells after treated with DHA. Moreover, RT-PCR and Western blot were performed to test the alteration of associated genes on mRNA and protein level in DHA treated esophageal squamous cancer cell lines, respectively. Furthermore, tumor-bearing nude mice were employed to evaluate the anticancer effect of DHA in vivo. Results: We found that hTERT was significantly upregulated in esophageal squamous cancer both from TCGA database and our cohort also. Overexpression of hTERT evidently promoted the proliferation and migration of esophageal squamous cancer cells in vitro. Moreover, DHA could significantly inhibit the proliferation and migration of esophageal cancer cell lines Eca109, KYSE150, and TE1 in vitro, and significantly down-regulate the expression of hTERT on both mRNA and protein level in a time- and dose-dependent manner as well. Further studies showed that DHA could induce intracellular ROS production in esophageal cancer cells and down-regulate SP1 expression, a transcription factor that bound to the promoter region of hTERT gene. Moreover, overexpression of SP1 evidently promoted the proliferation and migration of Eca109 and TE1 cells. Intriguingly, rescue experiments showed that inhibiting ROS by NAC alleviated the downregulation of SP1 and hTERT in cells treated with DHA. Furthermore, overexpression of SP1 or hTERT could attenuate the inhibition effect of DHA on the proliferation and migration of Eca109 cells. In tumor-bearing nude mice model, DHA significantly inhibited the growth of esophageal squamous cancer xenografts, and downregulated the expression of SP1 and hTERT protein, while no side effects were observed from heart, kidney, liver, and lung tissues by HE stain. Conclusion: hTERT plays an oncogenic role in esophageal squamous cancer and might be a therapeutic target of DHA through regulating ROS/SP1 pathway.

hTERT Promotes CRC Proliferation and Migration by Recruiting YBX1 to Increase NRF2 Expression

High human telomerase reverse transcriptase (hTERT) expression is related to severe Colorectal Cancer (CRC) progression and negatively related to CRC patient survival. Previous studies have revealed that hTERT can reduce cancer cellular reactive oxygen species (ROS) levels and accelerate cancer progression; however, the mechanism remains poorly understood. NFE2-related factor 2 (NRF2) is a molecule that plays a significant role in regulating cellular ROS homeostasis, but whether there is a correlation between hTERT and NRF2 remains unclear. Here, we showed that hTERT increases CRC proliferation and migration by inducing NRF2 upregulation. We further found that hTERT increases NRF2 expression at both the mRNA and protein levels. Our data also revealed that hTERT primarily upregulates NRF2 by increasing NRF2 promoter activity rather than by regulating NRF2 mRNA or protein stability. Using DNA pull-down/MS analysis, we found that hTERT can recruit YBX1 to upregulate NRF2 promoter activity. We also found that hTERT/YBX1 may localize to the P2 region of the NRF2 promoter. Taken together, our results demonstrate that hTERT facilitates CRC proliferation and migration by upregulating NRF2 expression through the recruitment of the transcription factor YBX1 to activate the NRF2 promoter. These results provide a new theoretical basis for CRC treatment.

Current advances of endophytes as a platform for production of anti-cancer drug camptothecin

Camptothecin (CPT), a well-known monoterpenoid indole alkaloid with broad-spectrum anti-cancer activity, is produced from plants and endophytes. In view of the limitations of plants as sources of camptothecin in productivity and efficiency, endophytes serve as the fast growth, high cost-effectiveness, good reproducibility, and feasible genetic manipulation, so they have the potential to meet the huge market demand of the pharmaceutical industry. In this review, we summarized the isolation, identification and fermentation of CPT-producing endophytes, as well as the biosynthesis, extraction and detection of camptothecin from endophytes. Among them, we put emphasis on increasing the production of camptothecin in endophytes through different strategies such as changing the proportion of carbon, nitrogen and phosphate source, adding the precursors, elicitors or adsorbent resin, utilizing co-culture fermentation or fermenter culture. However, cell subculture and metabolic reprogramming affect the expression of camptothecin biosynthetic genes in CPT-producing endophytes, which poses a challenge to the industrial production of camptothecin. Therefore, it will be useful to gain insights through the review of these researches and provide alternative approaches to develop economical, eco-friendly and reliable natural products.

TERT-Regulation and Roles in Cancer Formation

Telomerase reverse transcriptase (TERT) is a catalytic subunit of telomerase. Telomerase complex plays a key role in cancer formation by telomere dependent or independent mechanisms. Telomere maintenance mechanisms include complex TERT changes such as gene amplifications, TERT structural variants, TERT promoter germline and somatic mutations, TERT epigenetic changes, and alternative lengthening of telomere. All of them are cancer specific at tissue histotype and at single cell level. TERT expression is regulated in tumors via multiple genetic and epigenetic alterations which affect telomerase activity. Telomerase activity via TERT expression has an impact on telomere length and can be a useful marker in diagnosis and prognosis of various cancers and a new therapy approach. In this review we want to highlight the main roles of TERT in different mechanisms of cancer development and regulation.

Characterization of spirostanol glycosides and furostanol glycosides from anemarrhenae rhizoma as dual targeted inhibitors of 5-lipoxygenase and Cyclooxygenase-2 by employing a combination of affinity ultrafiltration and HPLC/MS

BACKGROUND

Modulation of the arachidonic acid (AA) cascade via 5-lipoxygenase (5-LOX) and cyclooxygenase-2 (COX-2) represent the two major pathways for treatments of inflammation and pain. The design and development of inhibitors targeting both 5-LOX and COX-2 has gained increasing popularity. As evidenced, 5-LOX and COX-2 dual targeted inhibitors have recently emerged as the front runners of anti-inflammatory drugs with improved efficacy and reduced side effects. Natural products represent a rich resource for the discovery of dual targeted 5-LOX and COX-2 inhibitors. By combining affinity ultrafiltration and high-performance liquid chromatography-mass spectrometry (AUF-LC-MS), an efficient method was developed to identify spirostanol glycosides and furostanol glycosides as the 5-LOX/COX-2 dual inhibitors from saponins extract of Anemarrhenae Rhizoma (SEAR).

METHODS

A highly efficient method by combining affinity ultrafiltration and high-performance liquid chromatography-mass spectrometry (AUF-LC-MS) was first developed to screen and characterize the 5-LOX/COX-2 dual targeted inhibitors from SEAR. The structures of compounds in the ultrafiltrate were characterized by high resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS). In addition, in vitro 5-LOX/COX-2 inhibition assays and their dual expression in vivo were performed to confirm the inhibitory activities of the compounds screened by AUF-LC-MS. Molecular docking studies with the corresponding binding energy were obtained which fit nicely to both 5-LOX and COX-2 protein cavities and in agreement with our affinity studies.

RESULTS

A total of 5 compounds, timosaponin A-II, timosaponin A-III, timosaponin B-II, timosaponin B-III and anemarrhenasaponin I, were identified as potential 5-LOX/COX-2 dual targeted inhibitors with specific binding values > 1.5 and IC₅₀ ≤ 6.07 μM.

CONCLUSION

The present work demonstrated that spirostanol glycoside and furostanol glycoside were identified as two novel classes of dual inhibitors of 5-LOX/COX-2 enzymes by employing a highly efficient screening method of AUF-LC-MS. These natural products represent a novel class of anti-inflammatory agents with the potential of improved efficacy and reduced side effects.

Lithium and the Interplay Between Telomeres and Mitochondria in Bipolar Disorder

Bipolar disorder is a severe psychiatric disorder which affects more than 1% of the world's population and is a leading cause of disability among young people. For the past 50 years, lithium has been the drug of choice for maintenance treatment of bipolar disorder due to its potent ability to prevent both manic and depressive episodes as well as suicide. However, though lithium has been associated with a multitude of effects within different cellular pathways and biological systems, its specific mechanism of action in stabilizing mood remains largely elusive. Mitochondrial dysfunction and telomere shortening have been implicated in both the pathophysiology of bipolar disorder and as targets of lithium treatment. Interestingly, it has in recent years become clear that these phenomena are intimately linked, partly through reactive oxygen species signaling and the subcellular translocation and non-canonical actions of telomerase reverse transcriptase. In this review, we integrate the current understanding of mitochondrial dysfunction, oxidative stress and telomere shortening in bipolar disorder with documented effects of lithium. Moreover, we propose that lithium's mechanism of action is intimately connected with the interdependent regulation of mitochondrial bioenergetics and telomere maintenance.

The mechanism of SP1/p300 complex promotes proliferation of multiple myeloma cells through regulating IQGAP1 transcription

Our previous research had firstly shown that MM cells overexpressed IQGAP1 gene and activated Ras/Raf/MEK/ERK pathway. But the mechanism of IQGAP1 overexpression and IQGAP1 gene transcription regulation remains uncertain. The mechanism of IQGAP1 overexpression and transcriptional regulation of IQGAP1 gene in myeloma cells was explored in the study. Through bioinformatics analysis and prediction we predicted and screened transcription factor Sp1 as a possible upstream regulator of IQGAP1.The proliferation, cell cycle and downstream ERK1/2 and p-ERK1/2 proteins were detected after siRNA-IQGAP1 was transfected to myeloma cells. The expression of Sp1, p300, IQGAP1, p-ERK1/2 and ERK1/2 were detected after Sp1 and p300 were inhibited or overexpressed respectively. The dual-luciferase reporter system was used to detect the activity of IQGAP1 gene promoter. CHIP was used to detect the binding of the Sp1 and IQGAP1 promoter regions.CO-IP was used to explore the interaction between Sp1 and p300.The mRNA expression levels of Sp1,p300 and IQGAP1 of the myeloma patients were detected, and the correlation analysis of their mRNA expression levels were carried out. The results showed IQGAP1-siRNA inhibits cell proliferation, cell cycle, IQGAP1 expression and phosphorylation of ERK1/2 protein. Inhibition of Sp1 or p300 down-regulated ERK1/2 and IQGAP1 expression; overexpression of Sp1 or p300 up-regulated ERK1/2 and IQGAP1 expression; Sp1 and p300 had a positive regulation effect on IQGAP1.Over expression of Sp1 or p300 significantly increased activity of IQGAP1 gene promoter. The transcription factor Sp1 plays a regulatory role in the IQGAP1 promoter region. There is an interaction between Sp1 and p300 in myeloma cells. The mRNA expression levels of Sp1, IQGAP1 and p300 in MM samples showed a positive correlation. In summary IQGAP1 is required for cell proliferation in MM cells, and the transcription of Sp1/p300 complex regulates expression of IQGAP1 gene.