Cisplatin liposome and 6-amino nicotinamide combination to overcome drug resistance in ovarian cancer cells

Improved anti-breast cancer activity by doxorubicin-loaded super stealth liposomes

PEGylation is currently used for the synthesis of stealth liposomes and to enhance the pharmacokinetic and biopharmaceutical properties of payloads. PEGylated dendron phospholipids can decrease the detachment of polyethylene glycol (PEG) from the liposomal surface owing to an increased hydrophobic anchoring effect on the phospholipid bilayer of liposomes and thus generating super stealth liposomes that are suitable for the systemic delivery of anticancer drugs. Herein, doxorubicin hydrochloride-loaded super stealth liposomes were studied for the treatment of breast cancer lung metastasis in an animal model. The results demonstrated that the super stealth liposomes had suitable physicochemical properties for in vivo administration and could significantly increase the efficacy of doxorubicin in breast cancer lung metastasis tumor-bearing mice compared to the free drug. The super stealth liposomes also increased doxorubicin accumulation inside the tumor tissue. The permanence of PEG on the surface of the super stealth liposomes favored the formation of a depot of therapeutic nanocarriers inside the tumor tissue by improving their permanence after stopping treatment. The doxorubicin-loaded super stealth liposomes increased the survival of the mouse tumor model. These promising results demonstrate that the doxorubicin-loaded super stealth liposomes could be an effective nanomedicine to treat metastatic breast cancer.

Site-specific delivery of cisplatin and paclitaxel mediated by liposomes: A promising approach in cancer chemotherapy

The site-specific delivery of drugs, especially anti-cancer drugs has been an interesting field for researchers and the reason is low accumulation of cytotoxic drugs in cancer cells. Although combination cancer therapy has been beneficial in providing cancer drug sensitivity, targeted delivery of drugs appears to be more efficient. One of the safe, biocompatible and efficient nano-scale delivery systems in anti-cancer drug delivery is liposomes. Their particle size is small and they have other properties such as adjustable physico-chemical properties, ease of functionalization and high entrapment efficiency. Cisplatin is a chemotherapy drug with clinical approval in patients, but its accumulation in cancer cells is low due to lack of targeted delivery and repeated administration results in resistance development. Gene and drug co-administration along with cisplatin/paclitaxel have resulted in increased sensitivity in tumor cells, but there is still space for more progress in cancer therapy. The delivery of cisplatin/paclitaxel by liposomes increases accumulation of drug in tumor cells and impairs activity of efflux pumps in promoting cytotoxicity. Moreover, phototherapy along with cisplatin/paclitaxel delivery can increase potential in tumor suppression. Smart nanoparticles including pH-sensitive nanoparticles provide site-specific delivery of cisplatin/paclitaxel. The functionalization of liposomes can be performed by ligands to increase targetability towards tumor cells in mediating site-specific delivery of cisplatin/paclitaxel. Finally, liposomes can mediate co-delivery of cisplatin/paclitaxel with drugs or genes in potentiating tumor suppression. Since drug resistance has caused therapy failure in cancer patients, and cisplatin/paclitaxel are among popular chemotherapy drugs, delivery of these drugs mediates targeted suppression of cancers and prevents development of drug resistance. Because of biocompatibility and safety of liposomes, they are currently used in clinical trials for treatment of cancer patients. In future, the optimal dose of using liposomes and optimal concentration of loading cisplatin/paclitaxel on liposomal nanocarriers in clinical trials should be determined.

Anti-HER2 Super Stealth Immunoliposomes for Targeted-Chemotherapy

Liposomes play an important role in the field of drug delivery by virtue of their biocompatibility and versatility as carriers. Stealth liposomes, obtained by surface decoration with hydrophilic polyethylene glycol (PEG) molecules, represent an important turning point in liposome technology, leading to significant improvements in the pharmacokinetic profile compared to naked liposomes. Nevertheless, the generation of effective targeted liposomes-a central issue for cancer therapy-has faced several difficulties and clinical phase failures. Active targeting remains a challenge for liposomes. In this direction, a new Super Stealth Immunoliposomes (SSIL2) composed of a PEG-bi-phospholipids derivative is designed that stabilizes the polymer shielding over the liposomes. Furthermore, its counterpart, conjugated to the fragment antigen-binding of trastuzumab (Fab'TRZ -PEG-bi-phospholipids), is firmly anchored on the liposomes surface and correctly orients outward the targeting moiety. Throughout this study, the performances of SSIL2 are evaluated and compared to classic stealth liposomes and stealth immunoliposomes in vitro in a panel of cell lines and in vivo studies in zebrafish larvae and rodent models. Overall, SSIL2 shows superior in vitro and in vivo outcomes, both in terms of safety and anticancer efficacy, thus representing a step forward in targeted cancer therapy, and valuable for future development.

Are we still on the right path(way)?: the altered expression of the pentose phosphate pathway in solid tumors and the potential of its inhibition in combination therapy

INTRODUCTION

The pentose phosphate pathway (PPP) branches from glycolysis and is crucial for cell growth, since it provides necessary compounds for anabolic reactions, nucleotide synthesis, and detoxification of reactive-oxygen-species (ROS). Overexpression of PPP enzymes has been reported in multiple cancer types and linked to therapy resistance, making their inhibition interesting targets for anti-cancer therapies.

AREAS COVERED

This review summarizes the extent of PPP upregulation across different cancer types, and the non-metabolic functions that PPP-enzymes might contribute to cancer initiation and maintenance. The effects of PPP-inhibition and their combinations with chemotherapeutics are summarized. We searched the databases provided by the University of Amsterdam to characterize the altered expression of the PPP across different cancer types, and to identify the effects of PPP-inhibition.

EXPERT OPINION

It can be concluded that there are synergistic and additive effects of PPP-inhibition and various classes of chemotherapeutics. These effects may be attributed to the increased susceptibility to ROS. However, the toxicity, low efficacy, and off-target effects of PPP-inhibitors make application in clinical practice challenging. Novel inhibitors are currently being developed, which could make PPP-inhibition a potential therapeutic strategy in the future, especially in combination with conventional chemotherapeutics and the inhibition of other metabolic pathways.

pH-responsive cisplatin-loaded niosomes: synthesis, characterization, cytotoxicity study and interaction analyses by simulation methodology

Cisplatin (Cis) is an effective cytotoxic agent, but its administration has been challenged by kidney problems, reduced immunity system, chronic neurotoxicity, and hemorrhage. To address these issues, pH-responsive non-ionic surfactant vesicles (niosomes) by Span 60 and Tween 60 derivatized by cholesteryl hemisuccinate (CHEMS), a pH-responsive agent, and Ergosterol (helper lipid), were developed for the first time to deliver Cis. The drug was encapsulated in the niosomes with a high encapsulation efficiency of 89%. This system provided a responsive release of Cis in pH 5.4 and 7.4, thereby improving its targeted anticancer drug delivery. The noisome bilayer model was studied by molecular dynamic simulation containing Tween 60, Span 60, Ergosterol, and Cis molecules to understand the interactions between the loaded drug and noisome constituents. We found that the platinum and chlorine atoms in Cis are critical factors in distributing the drug between water and bilayer surface. Finally, the lethal effect of niosomal Cis was investigated on the MCF7 breast cancer cell line using 3-(4, 5-Dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay. Results from morphology monitoring and cytotoxic assessments suggested a better cell-killing effect for niosomal Cis than standard Cis. Together, the synthesis of stimuli-responsive niosomes could represent a promising delivery strategy for anticancer drugs.

New potential antiproliferative monophosphoester 2-aminoethyl dihydrogen phosphate in K-562 and K-562 MDR+ leukemia cells

The main obstacle in the treatment of cancer patients has been resistance to multiple drugs, leading to the need to develop molecules with a higher specificity target. The liposomal formulation DODAC/2-AEH₂P has antitumor potential, inducing apoptosis in several tumor types. Human chronic myeloid leukemia K-562 and K-562 Lucena (MDR⁺) cells were treated with the DODAC carrier and the liposomal formulation 2-AEH₂P. Viability, cell cycle phases, apoptosis, marker expression and mitochondrial potential were analyzed. Significant reduction in viability was observed for all treatments. Changes in the distribution of the cell cycle phases and expression of markers involved in the apoptosis pathways were observed. Reduction of the mitochondrial electrical potential mediated by Bcl-2, being regulated by the reduction of the MTCH2 protein linked to the progression of myeloid leukemia and an increase in the pro-apoptotic proteins Bad and Bax, dependent on p53. This study demonstrated a significant therapeutic potential through apoptotic effects in leukemic cells, regardless of the molecular resistance profile (MDR⁺).

Co-Encapsulation of Fisetin and Cisplatin into Liposomes for Glioma Therapy: From Formulation to Cell Evaluation

(1) Background: Glioblastoma (GBM) is the most frequent cerebral tumor. It almost always relapses and there is no validated treatment for second-line GBM. We proposed the coencapsulation of fisetin and cisplatin into liposomes, aiming to (i) obtain a synergistic effect by combining the anti-angiogenic effect of fisetin with the cytotoxic effect of cisplatin, and (ii) administrate fisetin, highly insoluble in water. The design of a liposomal formulation able to encapsulate, retain and deliver both drugs appeared a challenge. (2) Methods: Liposomes with increasing ratios of cholesterol/DOPC were prepared and characterized in term of size, PDI and stability. The incorporation of fisetin was explored using DSC. The antiangiogneic and cytotoxic activities of the selected formulation were assayed in vitro. (3) Results: We successfully developed an optimized liposomal formulation incorporating both drugs, composed by DOPC/cholesterol/DODA-GLY-PEG2000 at a molar ratio of 75.3/20.8/3.9, with a diameter of 173 ± 8 nm (PDI = 0.12 ± 0.01) and a fisetin and cisplatin drug loading of 1.7 ± 0.3% and 0.8 ± 0.1%, respectively, with a relative stability over time. The maximum incorporation of fisetin into the bilayer was determined at 3.2% w/w. Then, the antiangiogenic activity of fisetin was maintained after encapsulation. The formulation showed an additive effect of cisplatin and fisetin on GBM cells; (4) Conclusions: The developed co-loaded formulation was able to retain the activity of fisetin, was effective against GBM cells and is promising for further in vivo experimentations.

Abnormal saccharides affecting cancer multi-drug resistance (MDR) and the reversal strategies

Clinically, chemotherapy is the mainstay in the treatment of multiple cancers. However, highly adaptable and activated survival signaling pathways of cancer cells readily emerge after long exposure to chemotherapeutics drugs, resulting in multi-drug resistance (MDR) and treatment failure. Recently, growing evidences indicate that the molecular action mechanisms of cancer MDR are closely associated with abnormalities in saccharides. In this review, saccharides affecting cancer MDR development are elaborated and analyzed in terms of aberrant aerobic glycolysis and its related enzymes, abnormal glycan structures and their associated enzymes, and glycoproteins. The reversal strategies including depletion of ATP, circumventing the original MDR pathway, activation by or inhibition of sugar-related enzymes, combination therapy with traditional cytotoxic agents, and direct modification on the sugar moiety, are ultimately proposed. It follows that abnormal saccharides have a significant effect on cancer MDR development, providing a new perspective for overcoming MDR and improving the outcome of chemotherapy.

Characterization and Pharmacokinetic Evaluation of Oxaliplatin Long-Circulating Liposomes

The clinical efficacy of Oxaliplatin (L-OHP) is potentially limited by dose-dependent neurotoxicity and high partitioning to erythrocytes in vivo. Long-circulating liposomes could improve the pharmacokinetic profile of L-OHP and thus enhance its therapeutic efficacy and reduce its toxicity. The purpose of this study was to prepare L-OHP long-circulating liposomes (L-OHP PEG lip) by reverse-phase evaporation method (REV) and investigate their pharmacokinetic behavior based on total platinum in rat plasma using atomic absorption spectrometry (AAS). A simple and a sensitive AAS method was developed and validated to determine the total platinum originated from L-OHP liposomes in plasma. Furthermore, long-circulating liposomes were fully characterized in vitro and showed great stability when stored at 4°C for one month. The results showed that the total platinum in plasma of L-OHP long-circulating liposomes displayed a biexponential pharmacokinetic profile with five folds higher bioavailability and longer distribution half-life compared to L-OHP solution. Thus, long-circulating liposomes prolonged L-OHP circulation time and may present a potential candidate for its tumor delivery. Conclusively, the developed AAS method could serve as a reference to investigate the pharmacokinetic behavior of total platinum in biological matrices for other L-OHP delivery systems.

Shifting the Gears of Metabolic Plasticity to Drive Cell State Transitions in Cancer

Cancer metabolism is a hallmark of cancer. Metabolic plasticity defines the ability of cancer cells to reprogram a plethora of metabolic pathways to meet unique energetic needs during the various steps of disease progression. Cell state transitions are phenotypic adaptations which confer distinct advantages that help cancer cells overcome progression hurdles, that include tumor initiation, expansive growth, resistance to therapy, metastasis, colonization, and relapse. It is increasingly appreciated that cancer cells need to appropriately reprogram their cellular metabolism in a timely manner to support the changes associated with new phenotypic cell states. We discuss metabolic alterations that may be adopted by cancer cells in relation to the maintenance of cancer stemness, activation of the epithelial-mesenchymal transition program for facilitating metastasis, and the acquisition of drug resistance. While such metabolic plasticity is harnessed by cancer cells for survival, their dependence and addiction towards certain metabolic pathways also present therapeutic opportunities that may be exploited.

The anti-malarial drug atovaquone potentiates platinum-mediated cancer cell death by increasing oxidative stress

Platinum chemotherapies are highly effective cytotoxic agents but often induce resistance when used as monotherapies. Combinatorial strategies limit this risk and provide effective treatment options for many cancers. Here, we repurpose atovaquone (ATQ), a well-tolerated & FDA-approved anti-malarial agent by demonstrating that it potentiates cancer cell death of a subset of platinums. We show that ATQ in combination with carboplatin or cisplatin induces striking and repeatable concentration- and time-dependent cell death sensitization in vitro across a variety of cancer cell lines. ATQ induces mitochondrial reactive oxygen species (mROS), depleting intracellular glutathione (GSH) pools in a concentration-dependent manner. The superoxide dismutase mimetic MnTBAP rescues ATQ-induced mROS production and pre-loading cells with the GSH prodrug N-acetyl cysteine (NAC) abrogates the sensitization. Together, these findings implicate ATQ-induced oxidative stress as key mediator of the sensitizing effect. At physiologically achievable concentrations, ATQ and carboplatin furthermore synergistically delay the growth of three-dimensional avascular spheroids. Clinically, ATQ is a safe and specific inhibitor of the electron transport chain (ETC) and is concurrently being repurposed as a candidate tumor hypoxia modifier. Together, these findings suggest that ATQ is deserving of further study as a candidate platinum sensitizing agent.

Nano liposomal and cubosomal formulations with platinum-based anticancer agents: therapeutic advances and challenges

Nephrotoxicity, neurotoxicity and multidrug resistance in tumor cells can result from platinum-based anticancer (PBA) agents which can be reduced by nano formulations. Recently, novel formulations based on liposomes and cubosomes have been described as efficient strategies to overcome nephrotoxicity, ototoxicity, neurotoxicity, cardiotoxicity, hematological toxicities, hepatotoxicity and gastrointestinal toxicity as well as multidrug resistance. The co-delivery of anticancer agents concomitant with PBAs via biocompatible and biodegradable smart liposomes and cubosomes can augment therapeutic results of chemotherapy as well as radiotherapy owing to their high accessibility of surface and internal modification. For this purpose, surface, bilayer or core sections of these formulations can be functionalized by pure PBAs or modified PBAs. In this review, recent significant advances and challenges related to various liposomal and cubosomal formulations of PBA are presented in order to emphasize suitable formulations for anticancer applications with critical thoughts provided on how the field can progress.

Metabolic regulation in HPV associated head and neck squamous cell carcinoma

Cancer cells exhibit distinct energy metabolic pathways due to multiple oncogenic events. In normoxia condition, the anaerobic glycolysis (Warburg effect) is highly observed in head and neck squamous cell carcinoma (HNSCC). HNSCC is associated with smoking, chewing tobacco, consumption of alcohol or Human Papillomavirus (HPV) infection primarily HPV16. In recent years, the correlation of HPV with HNSCC has significantly expanded. Despite the recent advancement in therapeutic approaches, the rate of HPV infected HNSCC has significantly increased in the last few years, specifically, in lower middle-income countries. The oncoproteins of High-risk Human Papillomavirus (HR-HPV), E6 and E7, alter the metabolic phenotype in HNSCC, which is distinct from non-HPV associated HNSCC. These oncoproteins, modulate the cell cycle and metabolic signalling through interacting with tumor suppressor proteins, p53 and pRb. Since, metabolic alteration represents a major hallmark for tumorigenesis, HPV acts as a source of biomarker linked to cancer progression in HNSCC. The dependency of cancer cells to specific nutrients and alteration of various metabolic associated genes may provide a unique opportunity for pharmacological intervention in HPV infected HNSCC. In this review, we have discussed the molecular mechanism (s) and metabolic regulation in HNSCC depending on the HPV status. We have also discussed the possible potential therapeutic approaches for HPV associated HNSCC through targeting metabolic pathways.

Combination Chemotherapy of Lung Cancer - Co-Delivery of Docetaxel Prodrug and Cisplatin Using Aptamer-Decorated Lipid-Polymer Hybrid Nanoparticles

Purpose

Lung cancer is the leading cause of cancer mortality worldwide. Drug resistance is the major barrier for the treatment of non-small cell lung cancer (NSCLC). The aim of this research is to develop an aptamer-decorated hybrid nanoparticle for the co-delivery of docetaxel prodrug (DTXp) and cisplatin (DDP) and to treat lung cancer.

Materials and Methods

Aptamer-conjugated lipid–polymer ligands and redox-sensitive docetaxel prodrug were synthesized. DTXp and DDP were loaded into the lipid–polymer hybrid nanoparticles (LPHNs). The targeted efficiency of aptamer-decorated, DTXp and DDP co-encapsulated LPHNs (APT-DTXp/DDP-LPHNs) was determined by performing a cell uptake assay by flow cytometry-based analysis. In vivo biodistribution and anticancer efficiency of APT-DTXp/DDP-LPHNs were evaluated on NSCLC-bearing mice xenograft.

Results

APT-DTXp/DDP-LPHNs had a particle size of 213.5 ± 5.3 nm, with a zeta potential of 15.9 ± 1.9 mV. APT-DTXp/DDP-LPHNs exhibited a significantly enhanced cytotoxicity (drug concentration causing 50% inhibition was 0.71 ± 0.09 μg/mL), synergy antitumor effect (combination index was 0.62), and profound tumor inhibition ability (tumor inhibition ratio of 81.4%) compared with the non-aptamer-decorated LPHNs and single drug-loaded LPHNs.

Conclusion

Since the synergistic effect of the drugs was found in this system, it would have great potential to inhibit lung tumor cells and in vivo tumor growth.

DGKA Provides Platinum Resistance in Ovarian Cancer Through Activation of c-JUN-WEE1 Signaling

PURPOSE

Although platinum compounds are the first-line treatment for ovarian cancer, the majority of patients relapse and develop resistance to treatment. However, the mechanism underlying resistance is unclear. The goal of our study is to decipher the mechanism by which a metabolic kinase, diacylglycerol kinase alpha (DGKA), confers platinum resistance in ovarian cancer.

EXPERIMENTAL DESIGN

Metabolic kinase RNAi synthetic lethal screening was used to identify a cisplatin resistance driver in ovarian cancer. DGKA variants were used to demonstrate the need for DGKA activity in cisplatin resistance. Phospho-proteomic and genomic screens were performed to identify downstream effectors of DGKA. Therapeutic efficacy of targeting DGKA was confirmed and clinical relevance of DGKA signaling was validated using ovarian cancer patient-derived tumors that had different responses to platinum-based therapy.

RESULTS

We found that platinum resistance was mediated by DGKA and its product, phosphatidic acid (PA), in ovarian cancer. Proteomic and genomic screens revealed that DGKA activates the transcription factor c-JUN and consequently enhances expression of a cell-cycle regulator, WEE1. Mechanistically, PA facilitates c-JUN N-terminal kinase recruitment to c-JUN and its nuclear localization, leading to c-JUN activation upon cisplatin exposure. Pharmacologic inhibition of DGKA sensitized ovarian cancer cells to cisplatin treatment and DGKA-c-JUN-WEE1 signaling positively correlated with platinum resistance in tumors derived from patients with ovarian cancer.

CONCLUSIONS

Our study demonstrates how the DGKA-derived lipid messenger, PA, contributes to cisplatin resistance by intertwining with kinase and transcription networks, and provides preclinical evidence for targeting DGKA as a new strategy in ovarian cancer treatment to battle cisplatin resistance.

Non-small cell lung cancer combination therapy: Hyaluronic acid modified, epidermal growth factor receptor targeted, pH sensitive lipid-polymer hybrid nanoparticles for the delivery of erlotinib plus bevacizumab

Non-small cell lung cancer (NSCLC) is the leading cause of cancer-related mortality in China. This study aimed to develop a hyaluronic acid (HA) decorated, pH sensitive lipid-polymer hybrid nanoparticles (LPH NPs) to co-deliver erlotinib (ERL) and bevacizumab (BEV) (HA-ERL/BEV-LPH NPs) for targeting and suppressing NSCLC. HA contained pH sensitive nano-materials were synthesized by acylation reaction. HA-ERL/BEV-LPH NPs were prepared using a sonication method. To explore the efficiency of the system, we evaluated the physicochemical parameters and performed a release study, a cellular uptake assay, a cytotoxicity evaluation, and several in vivo anti-tumor studies in comparison with free drugs and single drug systems. All LPH NPs samples have particle sizes of about 100-120 nm, polydispersity index values range from 0.12 to 0.15, and negative zeta potentials. HA-ERL/BEV-LPH NPs contained pH sensitive adipic acid dihydrazide (ADH) showed fast drug release at pH 5.5 than pH 7.4. After 21 days, the tumor volume of the HA-ERL/BEV-LPH NPs group (229.2 ± 13.1 mm³) was significantly smaller than 0.9 % NaCl control group (1126.3 ± 39.4 mm³), with a tumor inhibition rate of 79.7 ± 3.2 %. The maximum plasma ERL concentrations, half life period, and area under the curve of HA-ERL/BEV-LPH NPs were 21.6 μg/mL, 7.57 h, and 290.3 mg/L·h). With the highest tumor tissue accumulation concentration (25.3 μg/mL) and low system toxicity, HA-ERL/BEV-LPH NPs. HA-ERL/BEV-LPH NPs could be used as a promising system for the combination therapy of NSCLC.

Links between cancer metabolism and cisplatin resistance

Cisplatin is one of the most potent and widely used chemotherapeutic agent in the treatment of several solid tumors, despite the high toxicity and the frequent relapse of patients due to the onset of drug resistance. Resistance to chemotherapeutic agents, either intrinsic or acquired, is currently one of the major problems in oncology. Thus, understanding the biology of chemoresistance is fundamental in order to overcome this challenge and to improve the survival rate of patients. Studies over the last 30 decades have underlined how resistance is a multifactorial phenomenon not yet completely understood. Recently, tumor metabolism has gained a lot of interest in the context of chemoresistance; accumulating evidence suggests that the rearrangements of the principal metabolic pathways within cells, contributes to the sensitivity of tumor to the drug treatment. In this review, the principal metabolic alterations associated with cisplatin resistance are highlighted. Improving the knowledge of the influence of metabolism on cisplatin response is fundamental to identify new possible metabolic targets useful for combinatory treatments, in order to overcome cisplatin resistance.

The Pentose Phosphate Pathway and Its Involvement in Cisplatin Resistance

Cisplatin is the first-line treatment for different types of solid tumors, such as ovarian, testicular, bladder, cervical, head and neck, lung, and esophageal cancers. The main problem related to its clinical use is the onset of drug resistance. In the last decades, among the studied molecular mechanisms of cisplatin resistance, metabolic reprogramming has emerged as a possible one. This review focuses on the pentose phosphate pathway (PPP) playing a pivotal role in maintaining the high cell proliferation rate and representing an advantage for cancer cells. In particular, the oxidative branch of PPP plays a role in oxidative stress and seems to be involved in cisplatin resistance. In light of these considerations, it has been demonstrated that overexpression and higher enzymatic activity of different enzymes of both oxidative and non-oxidative branches (such as glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, and transketolase) increase cisplatin resistance, and their silencing or combined treatment with cisplatin could restore cisplatin sensitivity. Moreover, drug delivery systems loaded with both PPP inhibitors and cisplatin give the possibility of reaching cancer cells selectively. In conclusion, targeting PPP is becoming a strategy to overcome cisplatin resistance; however, further studies are required to better understand the mechanisms.

Niacin analogue, 6-Aminonicotinamide, a novel inhibitor of hepatitis B virus replication and HBsAg production

Background: Hepatitis B surface antigen (HBsAg) is one of the important clinical indexes for hepatitis B virus (HBV) infection diagnosis and sustained seroconversion of HBsAg is an indicator for functional cure. However, the level of HBsAg could not be reduced by interferons and nucleoside analogs effectively. Therefore, identification of a new drug targeting HBsAg is urgently needed.

Methods: In this study, 6-AN was screened out from 1500 compounds due to its low cytotoxicity and high antiviral activity. The effect of 6-AN on HBV was examined in HepAD38, HepG2-NTCP and PHHs cells. In addition, the antivirus effect of 6-AN was also identified in mouse model.

Findings: 6-AN treatment resulted in a significant decrease of HBsAg and other viral markers both in vitro and in vivo. Furthermore, we found that 6-AN inhibited the activities of HBV SpI, SpII and core promoter by decreasing transcription factor PPARα, subsequently reduced HBV RNAs transcription and HBsAg production.

Interpretation: We have identified a novel small molecule to inhibit HBV core DNA, HBV RNAs, HBsAg production, as well as cccDNA to a minor degree both in vitro and in vivo. This study may shed light on the development of a novel class of anti-HBV agent.

Semaphoring 4D is required for the induction of antioxidant stress and anti-inflammatory effects of dihydromyricetin in colon cancer

Semaphorin 4D (Sema4D) has been involved in cancer progression, the expression of which is associated with the poor clinical outcomes of some cancer patients. Dihydromyricetin (DMY) has antitumor potentials for different types of human cancer cells. However, the pharmacological effects of DMY on colon cancer (CC) or the regulatory effects of Sema4D on this process remain largely unknown. In the present study, we aimed to evaluate the effects of DMY on CC, and to elucidate the role of Sema4D in DMY-induced antitumor effects. DMY inhibited the proliferation and growth of Colo-205 colon cancer cells significantly in vivo and in vitro. DMY inhibited reactive oxygen species (ROS) and malondialdehyde (MDA) levels, but increased glutathione (GSH) level. Moreover, the activities of antioxidant enzymes catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx), glutathione reductase (GR) and heme oxygenase 1 (HO-1) were enhanced by DMY treatment in vitro, showing strong anti-oxidative stress effect. In addition, DMY inhibited the secretion of interleukin 1β (IL-1β), interleukin-6 (IL-6), interleukin-8 (IL-8) and tumor necrosis factor (TNF-α) in the supernatant of Colo-205 culture medium. Besides, the expressions of cyclooxygenase (COX-2) and inducible nitric oxide synthase (iNOS) were suppressed by DMY in dose-dependent manners in vivo, showing potent anti-inflammatory effect. Further investigations showed that DMY suppressed the expression and secretion of Sema4D in Colo-205 cells and tissues. Interestingly, overexpression of Sema4D significantly weakened the regulatory effects of DMY on oxidative stress. Furthermore, overexpression of Sema4D significantly attenuated the anti-inflammatory effects of DMY. Collectively, we drew a conclusion that the anti-colon cancer effect of DMY was attributed to its negative modulation on oxidative stress and inflammation via suppression of Sema4D. The findings broaden the width and depth of molecular mechanisms involved in the DMY action, facilitating the development of DMY in anti-colon cancer therapies.

The Influence of Metabolism on Drug Response in Cancer

Resistance to therapeutic agents, either intrinsic or acquired, is currently a major problem in the treatment of cancers and occurs in virtually every type of anti-cancer therapy. Therefore, understanding how resistance can be prevented, targeted and predicted becomes increasingly important to improve cancer therapy. In the last decade, it has become apparent that alterations in cellular metabolism are a hallmark of cancer cells and that a rewired metabolism is essential for rapid tumor growth and proliferation. Recently, metabolic alterations have been shown to play a role in the sensitivity of cancer cells to widely-used first-line chemotherapeutics. This suggests that metabolic pathways are important mediators of resistance toward anticancer agents. In this review, we highlight the metabolic alterations associated with resistance toward different anticancer agents and discuss how metabolism may be exploited to overcome drug resistance to classical chemotherapy.

Influence of 6-aminonicotinamide (6AN) on Leishmania promastigotes evaluated by metabolomics: Beyond the pentose phosphate pathway

6-Aminonicotinamide (6AN) is an antimetabolite used to inhibit the NADPH-producing pentose phosphate pathway (PPP) in many cellular systems, making them more susceptible to oxidative stress. It is converted by a NAD(P)⁺ glycohydrolase to 6-aminoNAD and 6-aminoNADP, causing the accumulation of PPP intermediates, due to their inability to participate in redox reactions. Some parasites like Plasmodium falciparum and Coccidia are highly sensitive but not all cell types showed a strong responsiveness to 6AN, probably due to the different targeted pathway. For instance, in bacteria the main target is the Preiss-Handler salvage pathway for NAD⁺ biosynthesis. We were interested in testing 6AN on the kinetoplastid protozoan Leishmania as another model to clarify the mechanisms of action of 6AN, by using metabolomics. Leishmania promastigotes, the life-cycle stage residing in the sandfly, demonstrated a three order of magnitude higher EC50 (mM) compared to P. falciparum and mammalian cells (μM), although pre-treatment with 100 μM 6AN prior to sub-lethal oxidative challenge induced a supra-additive cell kill in L. infantum. By metabolomics, we did not detect 6ANAD/P suggesting that NAD⁺ glycohydrolases in Leishmania may not be highly efficient in catalysing transglycosidation as happens in other microorganisms. Contrariwise to the reported effect on 6AN-treated cancer cells, we did not detect 6-phosphogluconate (6 PG) accumulation, indicating that 6ANADP cannot bind with high affinity to the PPP enzyme 6 PG dehydrogenase. By contrast, 6AN caused a profound phosphoribosylpyrophosphate (PRPP) decrease and nucleobases accumulation confirming that PPP is somehow affected. More importantly, we found a decrease in nicotinate production, evidencing the interference with the Preiss-Handler salvage pathway for NAD⁺ biosynthesis, most probably by inhibiting the reaction catalysed by nicotinamidase. Therefore, our combined data from Leishmania strains, though confirming the interference with PPP, also showed that 6AN impairs the Preiss-Handler pathway, underlining the importance to develop compounds targeting this last route.

Iron granules in plasma cells

Resistance of cancer cells to chemotherapy is the first cause of cancer-associated death. Thus, new strategies to deal with the evasion of drug response and to improve clinical outcomes are needed. Genetic and epigenetic mechanisms associated with uncontrolled cell growth result in metabolism reprogramming. Cancer cells enhance anabolic pathways and acquire the ability to use different carbon sources besides glucose. An oxygen and nutrient-poor tumor microenvironment determines metabolic interactions among normal cells, cancer cells and the immune system giving rise to metabolically heterogeneous tumors which will partially respond to metabolic therapy. Here we go into the best-known cancer metabolic profiles and discuss several studies that reported tumors sensitization to chemotherapy by modulating metabolic pathways. Uncovering metabolic dependencies across different chemotherapy treatments could help to rationalize the use of metabolic modulators to overcome therapy resistance.