Doxorubicin induces apoptosis and CD95 gene expression in human primary endothelial cells through a p53-dependent mechanism

An MDM2 degrader shows potent cytotoxicity to MDM2-overexpressing acute lymphoblastic leukemia cells with minimal toxicity to normal cells/tissues

The MDM2 oncogene is amplified and/or overexpressed in various human cancers and elevated expression of MDM2 protein acts as a survival factor promoting cancer progression through both p53-dependent and -independent pathways. Here, we report a novel small-molecule chemical compound (MX69-102) that we identified to induce MDM2 protein degradation, resulting in reactivation of p53, inhibition of XIAP, and potent cell growth inhibition and apoptosis in MDM2-overexpressing acute lymphoblastic leukemia (ALL) in vitro and in vivo. We have previously identified a compound (MX69) that binds to the MDM2 C-terminal RING domain and induces MDM2 protein degradation. In the present study, we performed structural modifications of MX69 and selected analog MX69-102, showing increased MDM2-targeting activity. MX69-102 exhibited significantly enhanced inhibitory and apoptotic effects on a group of MDM2-overexpressing ALL cell lines in vitro with IC50 values of about 0.2 μM, representing an approximately 38-fold increase in activity compared to MX69. MX69-102 also showed effective inhibition on xenografted human MDM2-overexpressing ALL in SCID mice. Importantly, MX69-102 had minimal or no inhibitory effect on normal human hematopoiesis in vitro and was very well tolerated in vivo in animal models. Based on the strong inhibitory and apoptotic activity against MDM2-overexpressing ALL, along with minimal or no toxicity to normal cells/tissues, MX69-102 is a candidate for further development as a novel MDM2-targeted therapeutic drug for refractory/MDM2-overexpressing ALL.

Cryptolepine Analog Exhibits Antitumor Activity against Ehrlich Ascites Carcinoma Cells in Mice via Targeting Cell Growth, Oxidative Stress, and PTEN/Akt/mTOR Signaling Pathway

BACKGROUND

The efficacy of chemotherapy continues to be limited due to associated toxicity and chemoresistance. Thus, synthesizing and investigating novel agents for cancer treatment that could potentially eliminate such limitations is imperative.

OBJECTIVE

The current study aims to explore the anticancer potency of cryptolepine (CPE) analog on Ehrlich ascites carcinoma cells (EACs) in mice.

METHODS

The effect of a CPE analog on EAC cell viability and ascites volume, as well as malonaldehyde, total antioxidant capacity, and catalase, were estimated. The concentration of caspase-8 and mTOR in EACs was also measured, and the expression levels of PTEN and Akt were determined.

RESULTS

Results revealed that CPE analog exerts a cytotoxic effect on EAC cell viability and reduces the ascites volume. Moreover, this analog induces oxidative stress in EACs by increasing the level of malonaldehyde and decreasing the level of total antioxidant capacity and catalase activity. It also induces apoptosis by elevating the concentration of caspase-8 in EACs. Furthermore, it decreases the concentration of mTOR in EACs. Moreover, it upregulates the expression of PTEN and downregulates the expression of Akt in EACs.

CONCLUSION

Our findings showed the anticancer activity of CPE analog against EACs in mice mediated by regulation of the PTEN/Akt/mTOR signaling pathway.

Emerging role and therapeutic implications of p53 in intervertebral disc degeneration

Lower back pain (LBP) is a common degenerative musculoskeletal disease that imposes a huge economic burden on both individuals and society. With the aggravation of social aging, the incidence of LBP has increased globally. Intervertebral disc degeneration (IDD) is the primary cause of LBP. Currently, IDD treatment strategies include physiotherapy, medication, and surgery; however, none can address the root cause by ending the degeneration of intervertebral discs (IVDs). However, in recent years, targeted therapy based on specific molecules has brought hope for treating IDD. The tumor suppressor gene p53 produces a transcription factor that regulates cell metabolism and survival. Recently, p53 was shown to play an important role in maintaining IVD microenvironment homeostasis by regulating IVD cell senescence, apoptosis, and metabolism by activating downstream target genes. This study reviews research progress regarding the potential role of p53 in IDD and discusses the challenges of targeting p53 in the treatment of IDD. This review will help to elucidate the pathogenesis of IDD and provide insights for the future development of precision treatments.

Morphine decreases cytotoxicity and mutagenicity of doxorubicin in vitro: Implications for cancer chemotherapy

Morphine is the most common opioid analgesic administered to treat pain in patients undergoing cancer chemotherapy. This study aimed to evaluate the cytotoxic and mutagenic effects of morphine alone and in combination with doxorubicin (Dox), an antineoplastic agent largely used in patients with solid cancers. Cytotoxicity was evaluated in neuroblastoma (SH-SY5Y) and fibroblast (V79) cells using 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide (MTT) colorimetric assay while mutagenicity was assessed using the Salmonella/microsome assay in the absence and in the presence of S9 mix. Morphine showed a cytotoxic effect mainly on SH-SY5Y cells and reduced the cytotoxic effects of Dox when evaluated in a co-treatment procedure. In the Salmonella/microsome assay, it was observed that morphine did not induce mutations and, in fact, decreased the mutagenic effects induced by Dox in TA98 and TA102 strains in the absence of metabolic activation. Furthermore, in the presence of metabolic activation, no induction of mutations was observed with morphine. In conclusion, morphine decreased Dox cytotoxicity in both neuronal and non-neuronal cells and showed antimutagenic effects in the TA102 strain which detects mutagens inducing DNA oxidative damages. However, morphine decreased frameshift mutations induced by Dox in non-cytotoxic concentrations, an effect suggesting interference of Dox intercalation activity that could decrease its chemotherapeutic efficacy. These compelling findings highlight the importance of conducting further studies to explore the potential implications of co-administering morphine and Dox during cancer chemotherapy.

Molecular mechanisms of endothelial remodeling under doxorubicin treatment

Doxorubicin (DOX) is an effective antineoplastic agent used to treat various types of cancers. However, its use is limited by the development of cardiotoxicity, which may result in heart failure. The exact mechanisms underlying DOX-induced cardiotoxicity are not fully understood, but recent studies have shown that endothelial-mesenchymal transition (EndMT) and endothelial damage play a crucial role in this process. EndMT is a biological process in which endothelial cells lose their characteristics and transform into mesenchymal cells, which have a fibroblast-like phenotype. This process has been shown to contribute to tissue fibrosis and remodeling in various diseases, including cancer and cardiovascular diseases. DOX-induced cardiotoxicity has been demonstrated to increase the expression of EndMT markers, suggesting that EndMT may play a critical role in the development of this condition. Furthermore, DOX-induced cardiotoxicity has been shown to cause endothelial damage, leading to the disruption of the endothelial barrier function and increased vascular permeability. This can result in the leakage of plasma proteins, leading to tissue edema and inflammation. Moreover, DOX can impair the production of nitric oxide, endothelin-1, neuregulin, thrombomodulin, thromboxane B2 etc. by endothelial cells, leading to vasoconstriction, thrombosis and further impairing cardiac function. In this regard, this review is devoted to the generalization and structuring of information about the known molecular mechanisms of endothelial remodeling under the action of DOX.

An integrative review of nonobvious puzzles of cellular and molecular cardiooncology

Oncologic patients are subjected to four major treatment types: surgery, radiotherapy, chemotherapy, and immunotherapy. All nonsurgical forms of cancer management are known to potentially violate the structural and functional integrity of the cardiovascular system. The prevalence and severity of cardiotoxicity and vascular abnormalities led to the emergence of a clinical subdiscipline, called cardiooncology. This relatively new, but rapidly expanding area of knowledge, primarily focuses on clinical observations linking the adverse effects of cancer therapy with deteriorated quality of life of cancer survivors and their increased morbidity and mortality. Cellular and molecular determinants of these relations are far less understood, mainly because of several unsolved paths and contradicting findings in the literature. In this article, we provide a comprehensive view of the cellular and molecular etiology of cardiooncology. We pay particular attention to various intracellular processes that arise in cardiomyocytes, vascular endothelial cells, and smooth muscle cells treated in experimentally-controlled conditions in vitro and in vivo with ionizing radiation and drugs representing diverse modes of anti-cancer activity.

A systematic evaluation of quenching and extraction procedures for quantitative metabolome profiling of HeLa carcinoma cell under 2D and 3D cell culture conditions

Metabolic reprogramming has been coined as a hallmark of cancer, accompanied by which the alterations in metabolite levels have profound effects on gene expression, cellular differentiation, and the tumor environment. Yet a systematic evaluation of quenching and extraction procedures for quantitative metabolome profiling of tumor cells is currently lacking. To achieve this, this study is aimed at establishing an unbiased and leakage-free metabolome preparation protocol for HeLa carcinoma cell. We evaluated 12 combinations of quenching and extraction methods from three quenchers (liquid nitrogen, -40°C 50% methanol, 0.5°C normal saline) and four extractants (-80°C 80% methanol, 0.5°C methanol/chloroform/water [1:1:1 v/v/v], 0.5°C 50% acetonitrile, 75°C 70% ethanol) for global metabolite profiling of adherent HeLa carcinoma cells. Based on the isotope dilution mass spectrometry (IDMS) method, gas/liquid chromatography in tandem with mass spectrometry was used to quantitatively determine 43 metabolites including sugar phosphates, organic acids, amino acids (AAs), adenosine nucleotides, and coenzymes involved in central carbon metabolism. The results showed that the total amount of the intracellular metabolites in cell extracts obtained using different sample preparation procedures with the IDMS method ranged from 21.51 to 295.33 nmol per million cells. Among 12 combinations, cells that washed twice with phosphate buffered saline (PBS), quenched with liquid nitrogen, and then extracted with 50% acetonitrile were found to be the most optimal method to acquire intracellular metabolites with high efficiency of metabolic arrest and minimal loss during sample preparation. In addition, the same conclusion was drawn as these 12 combinations were applied to obtain quantitative metabolome data from three-dimensional (3D) tumor spheroids. Furthermore, a case study was carried out to evaluate the effect of doxorubicin (DOX) on both adherent cells and 3D tumor spheroids using quantitative metabolite profiling. Pathway enrichment analysis using targeted metabolomics data showed that DOX exposure would significantly affect AA metabolism-related pathways, which might be related to the mitigation of redox stress. Strikingly, our data suggested that compared to two-dimensional (2D) cells the increased intracellular glutamine level in 3D cells benefited replenishing the tricarboxylic acid (TCA) cycle when the glycolysis was limited after dosing with DOX. Taken together, this study provides a well-established quenching and extraction protocol for quantitative metabolome profiling of HeLa carcinoma cell under 2D and 3D cell culture conditions. Based on this, quantitative time-resolved metabolite data can serve to the generation of hypotheses on metabolic reprogramming to reveal its important role in tumor development and treatment.

Biocompatible, Multi-Mode, Fluorescent, T2 MRI Contrast Magnetoelectric-Silica Nanoparticles (MagSiNs), for On-Demand Doxorubicin Delivery to Metastatic Cancer Cells

There is a need to improve current cancer treatment regimens to reduce systemic toxicity, to positively impact the quality-of-life post-treatment. We hypothesized the negation of off-target toxicity of anthracyclines (e.g., Doxorubicin) by delivering Doxorubicin on magneto-electric silica nanoparticles (Dox-MagSiNs) to cancer cells. Dox-MagSiNs were completely biocompatible with all cell types and are therapeutically inert till the release of Doxorubicin from the MagSiNs at the cancer cells location. The MagSiNs themselves are comprised of biocompatible components with a magnetostrictive cobalt ferrite core (4−6 nm) surrounded by a piezoelectric fused silica shell of 1.5 nm to 2 nm thickness. The MagSiNs possess T2-MRI contrast properties on par with RESOVIST™ due to their cobalt ferrite core. Additionally, the silica shell surrounding the core was volume loaded with green or red fluorophores to fluorescently track the MagSiNs in vitro. This makes the MagSiNs a suitable candidate for trackable, drug nanocarriers. We used metastatic triple-negative breast cancer cells (MDAMB231), ovarian cancer cells (A2780), and prostate cancer cells (PC3) as our model cancer cell lines. Human umbilical vein endothelial cells (HUVEC) were used as control cell lines to represent blood-vessel cells that suffer from the systemic toxicity of Doxorubicin. In the presence of an external magnetic field that is 300× times lower than an MRI field, we successfully nanoporated the cancer cells, then triggered the release of 500 nM of doxorubicin from Dox-MagSiNs to successfully kill >50% PC3, >50% A2780 cells, and killed 125% more MDAMB231 cells than free Dox.HCl. In control HUVECs, the Dox-MagSiNs did not nanoporate into the HUVECS and did not exhibited any cytotoxicity at all when there was no triggered release of Dox.HCl. Currently, the major advantages of our approach are, (i) the MagSiNs are biocompatible in vitro and in vivo; (ii) the label-free nanoporation of Dox-MagSiNs into cancer cells and not the model blood vessel cell line; (iii) the complete cancellation of the cytotoxicity of Doxorubicin in the Dox-MagSiNs form; (iv) the clinical impact of such a nanocarrier will be that it will be possible to increase the current upper limit for cumulative-dosages of anthracyclines through multiple dosing, which in turn will improve the anti-cancer efficacy of anthracyclines.

Thyme Oil and Thymol Counter Doxorubicin-Induced Hepatotoxicity via Modulation of Inflammation, Apoptosis, and Oxidative Stress

Doxorubicin (DOX) is an effective anticancer agent with a wide spectrum of activities. However, it has many adverse effects on various organs especially on the liver. Thymol, one of the major components of thyme oil, has biological properties that include anti-inflammatory and antioxidant activities. Thus, this study was designed to examine thyme oil and thymol for their ability to prevent doxorubicin-induced hepatotoxicity in Wistar rats. Hepatotoxicity was induced by an intraperitoneal injection of doxorubicin, at a dose of 2 mg/kg bw/week, for seven weeks. Doxorubicin-injected rats were supplemented with thyme oil and thymol at doses 250 and 100 mg/kg bw, respectively, four times/week by oral gavage for the same period. Treatment of rats with thyme oil and thymol reversed the high serum activities of AST, ALT, and ALP and total bilirubin, AFP, and CA19.9 levels, caused by doxorubicin. Thyme oil and thymol also reduced the high levels of TNF-α and the decreased levels of both albumin and IL-4. These agents ameliorated doxorubicin-induced elevation in hepatic lipid peroxidation and associated reduction in GSH content and GST and GPx activities. Further, the supplementation with thyme oil and thymol significantly augmented mRNA expression of the level of antiapoptotic protein Bcl-2 and significantly downregulated nuclear and cytoplasmic levels of the hepatic apoptotic mediator p53. Thus, thyme oil and thymol successfully counteracted doxorubicin-induced experimental hepatotoxicity via their anti-inflammatory, antioxidant, and antiapoptotic properties.

Comparative Study of the Pharmacological Properties and Biological Effects of Polygonum aviculare L. herba Extract-Entrapped Liposomes versus Quercetin-Entrapped Liposomes on Doxorubicin-Induced Toxicity on HUVECs

This study aimed to evaluate the comparative biological effects of Polygonum aviculare L. herba (PAH) extract and quercetin-entrapped liposomes on doxorubicin (Doxo)-induced toxicity in HUVECs. HUVECs were treated with two formulations of liposomes loaded with PAH extract (L5 and L6) and two formulations of liposomes loaded with quercetin (L3 prepared with phosphatidylcholine and L4 prepared with phosphatidylserine). The results obtained with atomic force microscopy, zeta potential and entrapment liposome efficiency confirmed the interactions of the liposomes with PAH or free quercetin and a controlled release of flavonoids entrapped in all the liposomes. Doxo decreased the cell viability and induced oxidative stress, inflammation, DNA lesions and apoptosis in parallel with the activation of Nrf2 and NF-kB. Free quercetin, L3 and L4 inhibited the oxidative stress and inflammation and reduced apoptosis, particularly L3. Additionally, these compounds diminished the Nrf2 and NF-kB expressions and DNA lesions, principally L4. PAH extract, L5 and L6 exerted antioxidant and anti-inflammatory activities, reduced γH2AX formation and inhibited extrinsic apoptosis and transcription factors activation but to a lesser extent. The loading of quercetin in liposomes increased the cell viability and exerted better endothelial protection compared to free quercetin, especially L3. The liposomes with PAH extract had moderate efficiency, mainly due to the antioxidant and anti-inflammatory effects and the inhibition of extrinsic apoptosis.

Antitumor activity of sitagliptin and vitamin B12 on Ehrlich ascites carcinoma solid tumor in mice

This study was carried out to investigate the potential effects of vitamin B12 and sitagliptin, and their possible synergistic effect with doxorubicin (DOX) on the Ehrlich solid tumor model. B12, sitagliptin, and their combination with DOX were administered to tumor-bearing mice for 21 days. Treatment with B12, sitagliptin, as well as their combinations with DOX caused a significant inhibition of tumor growth and increased the survival time. Malondialdehyde levels and the relative expression of tumor necrosis factor-α and nuclear factor kappa B were significantly decreased, whereas the total antioxidant capacity was significantly increased in all treated groups, except the DOX-treated one, when compared with the positive control group. Moreover, increased apoptosis was also observed by increased cleaved caspase-3 immunostaining and histopathological examination. In conclusion, the antitumor activity of B12 and sitagliptin could be attributed to their ability to induce apoptosis and suppress oxidative stress and inflammation.

MDM2 inhibition-mediated autophagy contributes to the pro-apoptotic effect of berberine in p53-null leukemic cells

AIMS

Berberine (BBR) is reported to induce apoptosis and inhibit migration of leukemic cells, but the underlying pharmacological mechanisms have not been fully revealed. This study aims to investigate the possible mechanisms from the perspective of autophagy.

MAIN METHODS

P-53-null leukemic cell lines Jurkat and U937 were used for the in vitro study. MDC staining was used for observation of autophagy in leukemic cells, and Western blot analysis was for determination of the expression levels of autophagy-associated proteins. Apoptosis of the leukemic cells was detected by flow cytometry. Cellular location of MDM2 was observed with immunofluorescence staining. Ubiquitination of MDM2 was assessed by immunoprecipitation. Male 6-8-week-old NOD/SCID mice were used for evaluating the effect of BBR on chemotherapy sensitivity in vivo.

KEY FINDINGS

BBR induced autophagy in p53-null leukemic cells, which was inhibited by autophagy inhibitors 3-methyladenine. 3-methyladenine also inhibited BBR-induced apoptosis in leukemic cells. In addition, BBR not only decreased MDM2 mRNA expression, but also enhanced MDM2 self-ubiquitination in leukemic cells. Forced overexpression of MDM2 reversed the effect of BBR on autophagy and apoptosis. Furthermore, BBR promoted doxorubicin-induced autophagy and cell death in the leukemic cells and overexpression of MDM2 suppressed these effects. In vivo, BBR combined with doxorubicin achieved better therapeutic effect than doxorubicin alone.

SIGNIFICANCE

MDM2 inhibits autophagy and apoptosis in leukemic cells in a p53-independent manner. BBR induces autophagy in p53-null leukemic cells through downregulating MDM2 expression at both transcriptional and post-transcriptional levels, which may contribute to the anti-cancer effect of BBR in leukemia.

Calcitriol Attenuates Doxorubicin-Induced Cardiac Dysfunction and Inhibits Endothelial-to-Mesenchymal Transition in Mice

Doxorubicin (Dox) is an effective anti-neoplasm drug, but its cardiac toxicity limits its clinical use. Endothelial-to-mesenchymal transition (EndMT) has been found to be involved in the process of heart failure. It is unclear whether EndMT contributes to Dox-induced cardiomyopathy (DoIC). Calcitriol, an active form Vitamin D3, blocks the growth of cancer cells by inhibiting the Smad pathway. To investigate the effect of calcitriol via inhibiting EndMT in DoIC, C57BL/6 mice and endothelial-specific labeled mice were intraperitoneally administered Dox twice weekly for 4 weeks (32 mg/kg cumulative dose) and were subsequently treated with or without calcitriol for 12 weeks. Echocardiography revealed diastolic dysfunction at 13 weeks following the first Dox treatment, accompanied by increased myocardial fibrosis and up-regulated pro-fibrotic proteins. Calcitriol attenuated Dox-induced myocardial fibrosis, down-regulated pro-fibrotic proteins and improved diastolic function. Endothelial fate tracing revealed that EndMT-derived cells contributed to Dox-induced cardiac fibrosis. In vitro, human umbilical vein endothelial cells and mouse cardiac fibroblasts were treated with Transforming growth factor (TGF)-β with or without calcitriol. Morphological, immunofluorescence staining, and Western blot analyses revealed that TGF-β-induced EndMT and fibroblast-to-myofibroblast transition (FMT) were attenuated by calcitriol by the inhibition of the Smad2 pathway. Collectively, calcitriol attenuated DoIC through the inhibition of the EndMT and FMT processes.

Nicorandil prevents doxorubicin-induced human umbilical vein endothelial cell apoptosis

Nicorandil is an adenosine triphosphate-sensitive potassium channel opener with additional antioxidant properties. Doxorubicin (DOX) is an anticancer drug that exerts oxidation-mediated adverse cardiovascular effects. This study examined the effects of nicorandil on DOX-induced cytotoxicity in human umbilical vein endothelial cells (HUVECs) and underlying intracellular signaling mechanisms. Cultured HUVECs were pretreated with nicorandil (0.1, 0.3, 1, 3, and 10 μM) for 12 h and then treated with DOX (1 μM) for 24 h. Cell viability and cytotoxicity were measured using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and lactate dehydrogenase assays, respectively. Cell apoptosis was examined using a caspase-3 activity assay, and DNA fragmentation was detected through TUNEL (terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling) staining. Western blot analysis was conducted to determine the related protein expression. DOX markedly increased reactive oxygen species production, p53 expression, caspase-3 activity, cleaved caspase-3 levels, and TUNEL-positive cell numbers but reduced Bcl-2 expression and intracellular antioxidant enzyme levels; these effects were effectively antagonized through nicorandil (3 μM, 12 h) pretreatment, which resulted in HUVECs being protected from DOX-induced apoptosis. Activating transcription factor 3 (ATF3), a stress-induced transcription factor, was induced by nicorandil (3 μM). Furthermore, nicorandil (3 μM) enhanced nuclear factor erythroid 2-related factor 2 (Nrf2) translocation and heme oxygenase-1 (HO-1) expression. ATF3 short interfering RNA significantly attenuated nicorandil-mediated Nrf2 translocation, HO-1 expression, and inhibitory effects on DOX-stimulated reactive oxygen species production and cell apoptosis. In summary, nicorandil may protect HUVECs from DOX-induced apoptosis, in part through ATF3-mediated Nrf2/HO-1 signaling pathways, which potentially protect the vessels from severe DOX toxicity.

NH4Cl treatment prevents doxorubicin-induced myocardial dysfunction in vivo

AIMS

Improvements in cancer treatment have significantly extended the lifespan of patients. However, due to the adverse effects of cancer treatment, cancer survivors are at increased risk of cardiovascular complications. Doxorubicin is a widely used spectrum antitumor drug, but the life-threatening side-effect of cardiotoxicity limits its clinical application. Ammonium chloride (NH₄Cl), as a heteropolar compound with pH value regulation, can cause intracellular alkalization and metabolic acidosis thus effecting enzymatic activity and influencing the process of biological system. The underlying effect of NH₄CL in DOX-induced cardiomyocyte apoptosis and hypertrophy in mice has never been reported before.

MAIN METHODS

This study we used DOX to induce cardiac remodeling and dysfunction in mice. Myocardial histology was performed using HE staining. Myocardial cell size was measured by wheat germ agglutinin (WGA) staining. Echocardiographic evaluation of cardiac function, qPCR detection of the mRNA expression of cardiac hypertrophy and inflammation markers. Apoptosis was detected by TUNEL method. Transmission electron microscopy (TEM) was used to detect autophagy.

KEY FINDINGS

We found that NH₄CL effectively improved DOX-induced cardiomyocyte apoptosis and cardiac dysfunction in mice. Our results showed that NH₄CL significantly improved DOX-induced contractile dysfunction, inflammation, apoptosis and autophagy in mice.

SIGNIFICANCE

Our results indicate that NH₄CL is effective in improving DOX-induced cardiac dysfunction and remodeling. It may therefore be a therapeutic entry point to limit doxorubicin-mediated adverse cardiac reactions.

LncRNA Meg3 protects endothelial function by regulating the DNA damage response

The role of long non-coding RNAs (lncRNAs) in regulating endothelial function through the DNA damage response (DDR) remains poorly understood. In this study, we demonstrate that lncRNA maternally expressed gene 3 (Meg3) interacts with the RNA binding protein polypyrimidine tract binding protein 3 (PTBP3) to regulate gene expression and endothelial function through p53 signaling ─ a major coordinator of apoptosis and cell proliferation triggered by the DDR. Meg3 expression is induced in endothelial cells (ECs) upon p53 activation. Meg3 silencing induces DNA damage, activates p53 signaling, increases the expression of p53 target genes, promotes EC apoptosis, and inhibits EC proliferation. Mechanistically, Meg3 silencing reduces the interaction of p53 with Mdm2, induces p53 expression, and promotes the association of p53 with the promoters of a subset of p53 target genes. PTBP3 silencing recapitulates the effects of Meg3 deficiency on the expression of p53 target genes, EC apoptosis and proliferation. The Meg3-dependent association of PTBP3 with the promoters of p53 target genes suggests that Meg3 and PTBP3 restrain p53 activation. Our studies reveal a novel role of Meg3 and PTBP3 in regulating p53 signaling and endothelial function, which may serve as novel targets for therapies to restore endothelial homeostasis.

Role of Endothelium in Doxorubicin-Induced Cardiomyopathy

The clinical use of doxorubicin in cancer is limited by cardiotoxic effects that can lead to heart failure. Whereas earlier work focused on the direct impact of doxorubicin on cardiomyocytes, recent studies have turned to the endothelium, because doxorubicin-damaged endothelial cells can trigger the development and progression of cardiomyopathy by decreasing the release and activity of key endothelial factors and inducing endothelial cell death. Thus, the endothelium represents a novel target for improving the detection, management, and prevention of doxorubicin-induced cardiomyopathy.

Pifithrin-α enhancing anticancer effect of topotecan on p53-expressing cancer cells

p53 is generally known as an effective anti-cancer molecular, but it is lost or mutated in more than 50% of human tumors. It is still a controversial issue whether the activity of p53 really benefits for treating cancers, we wondered what would happen if the endogenous p53 was inhibited before treated with topotecan (TPT) on p53 positive tumor cells. In this study, pifithrin-α (PFTα), a p53 inhibitor, was used 2 h before treated with TPT on three kinds of cancer cell lines including MCF7, BGC823 and HepG2 cells. The IC₅₀s of TPT for MCF7, BGC823 and HepG2 cells after 10 μΜ PFTα pretreated, was 4.8 to 14.4 folds lower than the effect of TPT alone. It was demonstrated that PFTα decreases the p-p53 levels and p-p53 activity, not affects p53 expression in p53 positive tumor cells. PFTα enhanced anticancer effect of TPT on cells was found mainly by two ways. Firstly, it increased the TPT accumulation in cells and nucleus and promoted the inhibition of TPT on activity of Topo I, and induced more DNA damage. Secondly, PFTα decreased formation of p53/mdm2 complex responsible for p53 degradation by inhibiting the protein expression of mdm2, so p53 degradation was decreased in cytoplasm and p53 accumulation was increased in nucleus, which induced more cells undergo apoptosis. So, the crosstalk between p53 and TPT played a pivotal role for enhancing anticancer effects of PFTα and TPT on p53 positive cancer cells. These findings provide a new idea for drug design and combination chemotherapy of cancers.

Efficacy of metformin in mediating cellular uptake and inducing apoptosis activity of doxorubicin

The clinical use of doxorubicin (DOX) is limited due to its systemic side effects and drug resistance. Recent evidence suggests that metformin prevents and controls certain but not all types of cancer. The beneficial use of metformin in combination with some chemotherapeutic agents has been reported. The aim of this study is to investigate the influence of metformin on DOX-induced effects in human prostate DU145 cancer cells and clarify its molecular mechanisms. For this purpose, DU145 cells were treated with DOX or metformin, either alone or in combination with each other. The proliferation of DU145 cells was inhibited by DOX-alone and metformin-alone treatment in a time and dose-dependent manner. Metformin could enhance the cytotoxicity of DOX by increasing DOX cellular uptake and cell cycle arrest at G1/S checkpoint which is associated with the enhancement of p21 protein expression. Moreover, metformin could elevate DOX-induced apoptosis in DU145 cells in a concentration-dependent manner and DOX-induced caspase-3 activity. These findings suggest that the combined treatment of metformin with DOX potentiates the anticancer efficacy of DOX in DU145 cells via inhibiting ABCB1 function, cell cycle arrest at G1/S transition and apoptosis induction.

Inhibition of MDM2 by a Rhein-Derived Compound AQ-101 Suppresses Cancer Development in SCID Mice

A novel small-molecule anthraquinone (AQ) analogue, AQ-101, which was synthesized through chemical modification of the core structures of rhein, exhibited potent anticancer activity. In the present study, we evaluated the cancer-inhibiting mechanism of AQ-101 and tested the therapeutic potential of this compound for treating cancer in mice. We found that AQ-101 was able to induce MDM2 protein degradation through a self-ubiquitination and proteasome-mediated mechanism. This AQ-101-induced MDM2 downregulation led to activation of p53, which contributed to apoptosis of acute lymphoblastic leukemia (ALL), especially those with a wild-type p53 phenotype and MDM2 expression in vitro and in vivo When given for a period of 2 weeks (20 mg/kg/day, 3×/week), AQ-101 inhibited development of ALL in nude or SCID mice with a human ALL xenograft and achieved cure by the end of the 5-month experiment. Importantly, AQ-101 showed minimal or no inhibitory effect on normal human hematopoiesis in vitro and was well tolerated in vivo in animal models. Given that MDM2-overexpressing cancers are commonly refractory to current treatment options, our study results suggest that further development of AQ-101 is warranted, as it represents a potentially new, safe anticancer drug with a novel strategy for targeting MDM2. Mol Cancer Ther; 17(2); 497-507. ©2017 AACR.

Sirt1 Protects Endothelial Cells against LPS-Induced Barrier Dysfunction

Sepsis is a threatening health problem and characterized by microvascular dysfunction. In this study, we verified that LPS caused the downregulation of Sirt1 and the hyperpermeability of endothelial cells. Inhibition of Sirt1 with ex527 or Sirt1 siRNA displayed a higher permeability, while activation of Sirt1 with SRT1720 reversed the LPS-induced hyperpermeability, formation of fiber stress, and disruption of VE-cadherin distribution. In pulmonary microvascular vein endothelial cells isolated from wild-type mice, Sirt1 was attenuated upon LPS, while Sirt1 was preserved in a receptor of advanced glycation end product-knockout mice. The RAGE antibody could also diminish the downregulation and ubiquitination of Sirt1 in LPS-exposed human umbilical vein endothelial cells. An LPS-induced decrease in Sirt1 activity was attenuated by the RAGE antibody and TLR4 inhibitor. In vivo study also demonstrated the attenuating role of Sirt1 and RAGE knockout in LPS-induced increases in dextran leakage of mesenteric venules. Furthermore, activation of Sirt1 prevented LPS-induced decreases in the activity and expression of superoxide dismutase 2, as well as the increases in NADPH oxidase 4 and reactive oxygen species, while inhibition of Sirt1 aggravated the SOD2 decline. It also demonstrated that Sirt1-deacetylated p53 is required for p53 inactivation, which reversed the downregulation of β-catenin caused by LPS.

The role of p53-microRNA 200-Moesin axis in invasion and drug resistance of breast cancer cells

This study aimed to analyze the expression of microRNAs in relation to p53 status in breast cancer cells and to delineate the role of Moesin in this axis. We used three isogenic breast carcinoma cell lines MCF7 (with wild-type p53), 1001 (MCF7 with mutated p53), and MCF7-E6 (MCF7 in which p53 function was disrupted). MicroRNA expression was analyzed using microarray analysis and confirmed by real-time polymerase chain reaction. The 1001 clone with mutant p53 showed 22 upregulated and 25 downregulated microRNAs. The predicted targets of these 47 microRNAs were >700 human genes belonging to interesting functional groups such as stem cell development and maintenance. The most significantly downregulated microRNAs in the p53-mutant cell line were from the miR-200 family. We focused on miR-200c which targets many transcripts involved in epithelial-to-mesenchymal transition including Moesin. We found that Moesin was expressed in 1001 but not in its p53 wild-type parental MCF7 consistent with the observed mesenchymal features in the 1001, such as vimentin positivity, E-cadherin negativity, and ZEB1 positivity in addition to the morphological changes. After Moesin silencing, the p53-mutant cells 1001 reverted from mesenchymal-to-epithelial phenotype and showed subtle reduction in migration and invasion and loss of ZEB1 and SNAIL expression. Interestingly, Moesin silencing restored the 1001 sensitivity to Doxorubicin. These results indicate that loss of miR-200c, as a consequence of p53 mutation, can upregulate Moesin oncogene and thus promote carcinogenesis. Moesin may play a role in metastasis and drug resistance of breast cancer.

Regulation of p53 and survivin by prodigiosin compound derived from Serratia marcescens contribute to caspase-3-dependent apoptosis in acute lymphoblastic leukemia cells

Tumor suppressor p53 and proto-oncogene survivin are challenging targets for anticancer drugs in acute lymphoblastic leukemia (ALL) which are associated with chemoresistance. Yet, no p53 and survivin-modulating drug with low toxicity and high efficacy has been approved for clinical application in ALL. Consequently, the search for novel compounds which target p53 or survivin is needed to further advance ALL treatment. Prodigiosin, a secondary metabolite of Serratia marcescens induces apoptosis in cancer cells with no toxicity on normal cells. However, the possible potential of prodigiosin as p53- and survivin-modulating agent in ALL cells has not been investigated. Wt-p53 Molt-4 cells were treated with 100 to 600 nM prodigiosin, after which, viability, cell proliferation rates, survivin and p53 protein levels, caspase-3 activation, and apoptosis were evaluated. After 24-, 48-, and 72-h treatments with 100 to 600 nM prodigiosin, cell proliferation rates were measured to be 93.7-77.3%, 75.5-58.3%, and 55-23.3%, respectively. Treatment for 48 hours with 100 to 600 nM prodigiosin resulted in 41-19% decrease in survivin protein levels followed by 450-950% increases in caspase-3 activation levels. Prodigiosin induced remarkably p53 accumulation and increased p53/survivin and caspase-3/survivin ratios by 6.1 to 11.3 and 10.3 to 47.5-fold at 100 to 600 nM, respectively. Survivin protein levels were inversely proportional to p53 accumulation levels. Low survivin protein levels combined with high levels of p53 accumulation were correlated to higher apoptotic rates. P53 and survivin as molecular targets of prodigiosin contribute to caspase-3-dependent apoptosis in ALL cells and this compound represents an attractive p53- and survivin-modulating agent in ALL.

Dual-targeted hybrid nanoparticles of synergistic drugs for treating lung metastases of triple negative breast cancer in mice

Lung metastasis is the major cause of death in patients with triple negative breast cancer (TNBC), an aggressive subtype of breast cancer with no effective therapy at present. It has been proposed that dual-targeted therapy, ie, targeting chemotherapeutic agents to both tumor vasculature and cancer cells, may offer some advantages. The present work was aimed to develop a dual-targeted synergistic drug combination nanomedicine for the treatment of lung metastases of TNBC. Thus, Arg-Gly-Asp peptide (RGD)-conjugated, doxorubicin (DOX) and mitomycin C (MMC) co-loaded polymer-lipid hybrid nanoparticles (RGD-DMPLN) were prepared and characterized. The synergism between DOX and MMC and the effect of RGD-DMPLN on cell morphology and cell viability were evaluated in human MDA-MB-231 cells in vitro. The optimal RGD density on nanoparticles (NPs) was identified based on the biodistribution and tumor accumulation of the NPs in a murine lung metastatic model of MDA-MB-231 cells. The microscopic distribution of RGD-conjugated NPs in lung metastases was examined using confocal microscopy. The anticancer efficacy of RGD-DMPLN was investigated in the lung metastatic model. A synergistic ratio of DOX and MMC was found in the MDA-MB-231 human TNBC cells. RGD-DMPLN induced morphological changes and enhanced cytotoxicity in vitro. NPs with a median RGD density showed the highest accumulation in lung metastases by targeting both tumor vasculature and cancer cells. Compared to free drugs, RGD-DMPLN exhibited significantly low toxicity to the host, liver and heart. Compared to non-targeted DMPLN or free drugs, administration of RGD-DMPLN (10 mg/kg, iv) resulted in a 4.7-fold and 31-fold reduction in the burden of lung metastases measured by bioluminescence imaging, a 2.4-fold and 4.0-fold reduction in the lung metastasis area index, and a 35% and 57% longer median survival time, respectively. Dual-targeted RGD-DMPLN, with optimal RGD density, significantly inhibited the progression of lung metastasis and extended host survival.

VEGF-ablation therapy reduces drug delivery and therapeutic response in ECM-dense tumors

The inadequate transport of drugs into the tumor tissue caused by its abnormal vasculature is a major obstacle to the treatment of cancer. Anti-vascular endothelial growth factor (anti-VEGF) drugs can cause phenotypic alteration and maturation of the tumor's vasculature. However, whether this consistently improves delivery and subsequent response to therapy is still controversial. Clinical results indicate that not all patients benefit from antiangiogenic treatment, necessitating the development of criteria to predict the effect of these agents in individual tumors. We demonstrate that, in anti-VEGF-refractory murine tumors, vascular changes after VEGF ablation result in reduced delivery leading to therapeutic failure. In these tumors, the impaired response after anti-VEGF treatment is directly linked to strong deposition of fibrillar extracellular matrix (ECM) components and high expression of lysyl oxidases. The resulting condensed, highly crosslinked ECM impeded drug permeation, protecting tumor cells from exposure to small-molecule drugs. The reduced vascular density after anti-VEGF treatment further decreased delivery in these tumors, an effect not compensated by the improved vessel quality. Pharmacological inhibition of lysyl oxidases improved drug delivery in various tumor models and reversed the negative effect of VEGF ablation on drug delivery and therapeutic response in anti-VEGF-resistant tumors. In conclusion, the vascular changes after anti-VEGF therapy can have a context-dependent negative impact on overall therapeutic efficacy. A determining factor is the tumor ECM, which strongly influences the effect of anti-VEGF therapy. Our results reveal the prospect to revert a possible negative effect and to potentiate responsiveness to antiangiogenic therapy by concomitantly targeting ECM-modifying enzymes.

Elastomeric free-form blood vessels for interconnecting organs on chip systems

Conventional blood vessel-on-a-chip models are typically based on microchannel-like structures enclosed within bulk elastomers such as polydimethylsiloxane (PDMS). However, these bulk vascular models largely function as individual platforms and exhibit limited flexibility particularly when used in conjunction with other organ modules. Oftentimes, lengthy connectors and/or tubes are still needed to interface multiple chips, resulting in a large waste volume counterintuitive to the miniaturized nature of organs-on-chips. In this work, we report the development of a novel form of a vascular module based on PDMS hollow tubes, which closely emulates the morphology and properties of human blood vessels to integrate multiple organs-on-chips. Specifically, we present two templating strategies to fabricate hollow PDMS tubes with adjustable diameters and wall thicknesses, where metal rods or airflow were employed as the inner templates, while plastic tubes were used as the outer template. The PDMS tubes could then be functionalized by human umbilical vein endothelial cells (HUVECs) in their interior surfaces to further construct elastomeric biomimetic blood vessels. The endothelium developed biofunctionality as demonstrated by the expression of an endothelial biomarker (CD31) as well as dose-dependent responses in the secretion of von Willebrand factor and nitric oxide upon treatment with pharmaceutical compounds. We believe that with their clear advantages including high optical transparency, gas permeability, and tunable elasticity matching those of native blood vessels, these free-form PDMS vascular modules can supplement bulk vascular organoids and likely replace inert plastic tubes in integrating multiple organoids into a single microfluidic circuitry.

Pterostilbene carboxaldehyde thiosemicarbazone, a resveratrol derivative inhibits 17β-Estradiol induced cell migration and proliferation in HUVECs

Angiogenesis plays important roles in tumor growth and metastasis, thus development of a novel angiogenesis inhibitor is essential for the improvement of therapeutics against cancer. Thrombospondins-1 (TSP-1) is a potent endogenous inhibitor of angiogenesis that acts through direct effects on endothelial cell migration, proliferation, survival, and activating apoptotic pathways. TSP-1 has been shown to disrupt estrogen-induced endothelial cell proliferation and migration. Here we investigated the potential of pterostilbene carboxaldehyde thiosemicarbazone (PTERC-T), a novel resveratrol (RESV) derivative, to inhibit angiogenesis induced by female sex steroids, particularly 17β-Estradiol (E2), on Human umbilical vein endothelial cells (HUVECs) and to elucidate the involvement of TSP-1 in PTERC-T action. Our results showed that PTERC-T significantly inhibited 17β-E2-stimulated proliferation of HUVECs and induced apoptosis as determined by annexin V/propidium iodide staining and cleaved caspase-3 expression. Furthermore, PTERC-T also inhibited endothelial cell migration, and invasion in chick chorioallantoic membrane (CAM) assay. In contrast, RESV failed to inhibit 17β-E2 induced HUVECs proliferation and invasion at similar dose. PTERC-T was also found to increase TSP-1 protein expression levels in a dose-dependent manner which, however, was counteracted by co-incubation with p38MAPK or JNK inhibitors, suggesting involvement of these pathways in PTERC-T action. These results suggest that the inhibitory effect of PTERC-T on 17β-E2 induced angiogenesis is associated, at least in part, with its induction of endothelial cell apoptosis and inhibition of cell migration through targeting TSP-1. Thus, PTERC-T could be considered as a potential lead compound for developing a class of new drugs targeting angiogenesis-related diseases.

Carfilzomib reverses pulmonary arterial hypertension

AIMS

Pulmonary arterial hypertension (PAH) remains a lethal disease with pronounced narrowing of pulmonary vessels due to abnormal cell growth. Agents that can reduce the pulmonary vascular thickness thus have therapeutic potential. The present study investigated the efficacy of carfilzomib (CFZ), a proteasome inhibitor and a cancer chemotherapeutic drug, on reversing PAH.

METHODS AND RESULTS

In two rat models of PAH, SU5416/hypoxia and SU5416/ovalbumin, CFZ effectively reversed pulmonary vascular remodelling with the promotion of apoptosis and autophagy. In human pulmonary artery smooth muscle cells, knocking down mediators of autophagy attenuated CFZ-induced cell death. The cell death role of autophagy was promoted by the participation of tumour protein p53-inducible nuclear protein 1. CFZ increased the protein ubiquitination, and siRNA knockdown of ubiquitin inhibited cell death, suggesting that CFZ-induced cell death is ubiquitin-dependent. Mass spectrometry demonstrated the ubiquitination of major vault protein and heat shock protein 90 in response to CFZ. The siRNA knockdown of these proteins enhanced CFZ-induced cell death, revealing that they are cell survival factors. CFZ reduced right-ventricular pressure and enhanced the efficacy of a vasodilator, sodium nitroprusside. While no indications of CFZ toxicity were observed in the right ventricle of PAH rats, apoptosis was promoted in the left ventricle. Apoptosis was prevented by dexrazoxane or by pifithrin-α without interfering with the efficacy of CFZ to reverse pulmonary vascular remodelling.

CONCLUSION

The addition of anti-tumour agents such as CFZ along with cardioprotectants to currently available vasodilators may be a promising way to improve PAH therapy.

The TGF-β pathway mediates doxorubicin effects on cardiac endothelial cells

Elevated ALK4/5 ligands including TGF-β and activins have been linked to cardiovascular remodeling and heart failure. Doxorubicin (Dox) is commonly used as a model of cardiomyopathy, a condition that often precedes cardiovascular remodeling and heart failure. In 7-8-week-old C57Bl/6 male mice treated with Dox we found decreased capillary density, increased levels of ALK4/5 ligand and Smad2/3 transcripts, and increased expression of Smad2/3 transcriptional targets. Human cardiac microvascular endothelial cells (HCMVEC) treated with Dox also showed increased levels of ALK4/5 ligands, Smad2/3 transcriptional targets, a decrease in proliferation and suppression of vascular network formation in a HCMVEC and human cardiac fibroblasts co-culture assay. Our hypothesis is that the deleterious effects of Dox on endothelial cells are mediated in part by the activation of the TGF-β pathway. We used the inhibitor of ALK4/5 kinases SB431542 (SB) in concert with Dox to ascertain the role of TGF-β pathway activation in doxorubicin induced endothelial cell defects. SB prevented the suppression of HCMVEC proliferation in the presence of TGF-β2 and activin A, and alleviated the inhibition of HCMVEC proliferation by Dox. SB also prevented the suppression of vascular network formation in co-cultures of HCMVEC and human cardiac fibroblasts treated with Dox. Our results show that the inhibition of the TGF-β pathway alleviates the detrimental effects of Dox on endothelial cells in vitro.

Strategy to enhance efficacy of doxorubicin in solid tumor cells by methyl-β-cyclodextrin: Involvement of p53 and Fas receptor ligand complex

Doxorubicin (DOX) is one of the preferred drugs for treating breast and liver cancers. However, its clinical application is limited due to severe side effects and the accompanying drug resistance. In this context, we investigated the effect on therapeutic efficacy of DOX by cholesterol depleting agent methyl-β-cyclodextrin (MCD), and explored the involvement of p53. MCD sensitizes MCF-7 and Hepa1–6 cells to DOX, Combination of MCD and marginal dose of DOX reduces the cell viability, and promoted apoptosis through induction of pro-apoptotic protein, Bax, activation of caspase-8 and caspase-7, down regulation of anti-apoptotic protein Bcl-2 and finally promoting PARP cleavage. Mechanistically, sensitization to DOX by MCD was due to the induction of FasR/FasL pathway through p53 activation. Furthermore, inhibition of p53 by pharmacological inhibitor pifithrin-α (PFT-α) or its specific siRNA attenuated p53 function and down-regulated FasR/FasL, thereby preventing cell death. Animal experiments were performed using C57BL/6J mouse isografted with Hepa1–6 cells. Tumor growth was retarded and survival increased in mice administered MCD together with DOX to as compared to either agent alone. Collectively, these results suggest that MCD enhances the sensitivity to DOX for which wild type p53 is an important determinant.

Macrophage mediated biomimetic delivery system for the treatment of lung metastasis of breast cancer

The biomimetic delivery system (BDS) based on special types of endogenous cells like macrophages and T cells, has been emerging as a novel strategy for cancer therapy, due to its tumor homing property and biocompatibility. However, its development is impeded by complicated construction, low drug loading or negative effect on the cell bioactivity. The present report constructed a BDS by loading doxorubicin (DOX) into a mouse macrophage-like cell line (RAW264.7). It was found that therapeutically meaningful amount of DOX could be loaded into the RAW264.7 cells by simply incubation, without significantly affecting the viability of the cells. Drug could release from the BDS and maintain its activity. RAW264.7 cells exhibited obvious tumor-tropic capacity towards 4T1 mouse breast cancer cells both in vitro and in vivo, and drug loading did not alter this tendency. Importantly, the DOX loaded macrophage system showed promising anti-cancer efficacy in terms of tumor suppression, life span prolongation and metastasis inhibition, with reduced toxicity. In conclusion, it is demonstrated that the BDS developed here seems to overcome some of the main issues related to a BDS. The DOX loaded macrophages might be a potential BDS for targeted cancer therapy.

Urotensin II inhibits doxorubicin-induced human umbilical vein endothelial cell death by modulating ATF expression and via the ERK and Akt pathway

Background and Purpose

Regulation of the homeostasis of vascular endothelium is critical for the processes of vascular remodeling and angiogenesis under physiological and pathological conditions. Urotensin II (U-II), a potent vasoactive peptide, participates in vascular and myocardial remodeling after injury. We investigated the protective effect of U-II on doxorubicin (DOX)-induced apoptosis in cultured human umbilical vein endothelial cells (HUVECs) and the potential mechanisms involved in this process.

Experimental Approach

Cultured HUVECs were treated with vehicle, DOX (1 µM), U-II, or U-II plus DOX. Apoptosis was evaluated by DNA strand break level with TdT-mediated dUTP nick-end labeling (TUNEL) staining. Western blot analysis was employed to determine the related protein expression and flow cytometry assay was used to determine the TUNEL positive cells.

Key Results

U-II reduced the quantity of cleaved caspase-3 and cytosol cytochrome c and increased Bcl-2 expression, which results in protecting HUVECs from DOX-induced apoptosis. U-II induced Activating transcription factor 3 (ATF3) at both mRNA and protein levels in U-II-treated cells. Knockdown of ATF3 with ATF3 siRNA significantly reduced ATF3 protein levels and U-II protective effect under DOX-treated condition. U-II downregulated p53 expression in DOX-induced HUVECs apoptosis, and it rapidly activated extracellular signal-regulated protein kinase (ERK) and Akt. The DOX induced change of p53 was not affected by U-II antagonist (urantide) under ATF-3 knockdown. The inhibitory effect of U-II on DOX-increased apoptosis was attenuated by inhibitors of ERK (U0126) and PI3K/Akt (LY294002).

Conclusion and Implications

Our observations provide evidence that U-II protects HUVECs from DOX-induced apoptosis. ERK-Akt phosphorylation, ATF3 activation, and p53 downregulation may play a signal-transduction role in this process.

In vivo Studies on the Protective Effect of Propolis on Doxorubicin-Induced Toxicity in Liver of Male Rats

Objective:

Since anticancer drugs are to be administered for long durations of time and are associated with systemic toxicities, the present studies were conducted to evaluate the protective potential of honey bee propolis against a widely used anticancer drug, doxorubicin (DXR) induced toxicity and oxidative damage in liver tissues of rats.

Materials and Methods:

Sixteen male Sprague Dawley rats, weighing between 200-220 g, were used and were divided into four equal groups. Propolis was given orally to rats [250 mg/kg body weight (bw) for 14 consecutive days] and DXR [25 mg/kg bw; intraperitoneally (i.p) was administered on 12^th, 13^th and 14^th day of the experiment. All the animals were sacrificed on day 15^th day by decapitation. Blood and tissue samples were collected for measurement of toxicity and oxidative damage parameters (enzymatic assays and biochemical estimations).

Results:

Administration of DXR for 3 days at a cumulative dose of 25 mg/kg bw, induced toxicity and oxidative stress in rats as significantly decreased activity of catalase (CAT), superoxide dismutase (SOD), glutathione-S-transferase (GST), glutathione peroxidase (GSH-Px) and glutathione reductase (GR) were observed in rat liver supernatants when compared to control group. Increased activity of serum glutamic pyruvic transaminase (SGPT) and serum glutamic oxaloacetic transaminase (SGOT) was obtained in DXR administered rats. Also there are significantly increased levels of lipid peroxides (measured as malondialdehyde formation) and significantly decreased level of glutathione (GSH) in doxorubicin treated rat liver supernatants as compared to healthy controls. On the other hand, administration of animals with propolis prior to DXR treatment led to significant modulation of the oxidative damage related parameters in liver and hepatotoxicity parameters in blood, when compared to doxorubicin treated group. However results were still not comparable to control group or only propolis group indicating partial protection by propolis at the concentration used against anticancer drug toxicity.

Conclusion:

Propolis extract was found to have a protective effect against doxorubicin-induced toxicity in rat liver though it was still not normalized. It can be concluded that propolis provides partial protection from toxicity of anticancer drug.

Death receptor 3 mediates TNFSF15- and TNFα-induced endothelial cell apoptosis

Tumor necrosis factor superfamily 15 (TNFSF15) suppresses angiogenesis by specifically inducing apoptosis in proliferating endothelial cells. Death receptor 3 (DR3), a member of the TNF receptor superfamily (TNFRSF25), has been identified as a receptor for TNFSF15 to activate T cells. It is unclear, however, whether DR3 mediates TNFSF15 activity on endothelial cells. Here we show that siRNA-mediated knockdown of DR3 in an in vivo Matrigel angiogenesis assay, or in adult bovine aortic endothelial (ABAE) cell cultures, leads to resistance of endothelial cells to TNFSF15-induced apoptosis. Interestingly, DR3-depleted cells also exhibited markedly diminished responsiveness to TNFα cytotoxicity, even though DR3 is not a receptor for TNFα. Treatment of the cells with either TNFSF15 siRNA or a TNFSF15-neutralizing antibody, 4-3H, also results in a significant inhibition of TNFα-induced apoptosis. Mechanistically, DR3 siRNA treatment gives rise to an increase of ERK1/2 MAPK activity, and up-regulation of the anti-apoptotic proteins c-FLIP and Bcl-2, thus strengthening apoptosis-resisting potential in the cells. These findings indicate that DR3 mediates TNFSF15-induced endothelial cell apoptosis, and that up-regulation of TNFSF15 expression stimulated by TNFα is partly but significantly responsible for TNFα-induced apoptosis in endothelial cells.

Removal of a small C-terminal region of JCV and SV40 large T antigens has differential effects on transformation

The large T antigen (LT) protein of JCV and SV40 polyomaviruses is required to induce tumors in rodents and transform cells in culture. When both LTs are compared side-by-side in cell culture assays, SV40 shows a more robust transformation phenotype even though the LT sequences are highly conserved. A complete understanding of SV40׳s enhanced transforming capabilities relative to JCV is lacking. When the least conserved region of the LT proteins, the variable linker and host range region (VHR), was removed, changes in T antigen expression and cellular p53 post-translational modifications occurred, but interaction with the pRB pathway was unaffected. Transformation assessed by growth in low serum was reduced after VHR truncation of the SV40, but not the JCV, T antigen. Conversely, anchorage independent transformation was enhanced only by truncation of the JCV VHR. This is the first report to link the SV40 or JCV VHR region to transformation potential.

Targeted delivery of doxorubicin-loaded poly (ε-caprolactone)-b-poly (N-vinylpyrrolidone) micelles enhances antitumor effect in lymphoma

Background

The present study was motivated by the need to design a safe nano-carrier for the delivery of doxorubicin which could be tolerant to normal cells. PCL₆₃-b-PNVP₉₀ was loaded with doxorubicin (6 mg/ml), and with 49.8% drug loading efficiency; it offers a unique platform providing selective immune responses against lymphoma.

Methods

In this study, we have used micelles of amphiphilic PCL₆₃-b-PNVP₉₀ block copolymer as nano-carrier for controlled release of doxorubicin (DOX). DOX is physically entrapped and stabilized in the hydrophobic cores of the micelles and biological roles of these micelles were evaluated in lymphoma.

Results

DOX loaded PCL₆₃-b-PNVP₉₀ block copolymer micelles (DOX-PCL₆₃-b-PNVP₉₀) shows enhanced growth inhibition and cytotoxicity against human (K-562, JE6.1 and Raji) and mice lymphoma cells (Dalton's lymphoma, DL). DOX-PCL₆₃-b-PNVP₉₀ demonstrates higher levels of tumoricidal effect against DOX-resistant tumor cells compared to free DOX. DOX-PCL₆₃-b-PNVP₉₀ demonstrated effective drug loading and a pH-responsive drug release character besides exhibiting sustained drug release performance in in-vitro and intracellular drug release experiments.

Conclusion

Unlike free DOX, DOX-PCL₆₃-b-PNVP₉₀ does not show cytotoxicity against normal cells. DOX-PCL₆₃-b-PNVP₉₀ prolonged the survival of tumor (DL) bearing mice by enhancing the apoptosis of the tumor cells in targeted organs like liver and spleen.

Transactivation of bad by vorinostat-induced acetylated p53 enhances doxorubicin-induced cytotoxicity in cervical cancer cells

Vorinostat (VOR) has been reported to enhance the cytotoxic effects of doxorubicin (DOX) with fewer side effects because of the lower DOX dosage in breast cancer cells. In this study, we investigated the novel mechanism underlying the synergistic cytotoxic effects of VOR and DOX co-treatment in cervical cancer cells HeLa, CaSki and SiHa cells. Co-treatment with VOR and DOX at marginal doses led to the induction of apoptosis through caspase-3 activation, poly (ADP-ribose) polymerase cleavage and DNA micronuclei. Notably, the synergistic growth inhibition induced by the co-treatment was attributed to the upregulation of the pro-apoptotic protein Bad, as the silencing of Bad expression using small interfering RNA (siRNA) abolished the phenomenon. As siRNA against p53 did not result in an increase in acetylated p53 and the consequent upregulation of Bad, the observed Bad upregulation was mediated by acetylated p53. Moreover, a chromatin immunoprecipitation analysis showed that the co-treatment of HeLa cells with VOR and DOX increased the recruitment of acetylated p53 to the bad promoter, with consequent bad transactivation. Conversely, C33A cervical cancer cells containing mutant p53 co-treated with VOR and DOX did not exhibit Bad upregulation, acetylated p53 induction or consequent synergistic growth inhibition. Together, the synergistic growth inhibition of cervical cancer cell lines induced by co-treatment with VOR and DOX can be attributed to the upregulation of Bad, which is induced by acetylated p53. These results show for the first time that the acetylation of p53, rather than histones, is a mechanism for the synergistic growth inhibition induced by VOR and DOX co-treatments.

Preeclampsia is associated with alterations in the p53-pathway in villous trophoblast

BACKGROUND

Preeclampsia (PE) is characterized by exaggerated apoptosis of the villous trophoblast of placental villi. Since p53 is a critical regulator of apoptosis we hypothesized that excessive apoptosis in PE is mediated by abnormal expression of proteins participating in the p53 pathway and that modulation of the p53 pathway alters trophoblast apoptosis in vitro.

METHODS

Fresh placental villous tissue was collected from normal pregnancies and pregnancies complicated by PE; Western blotting and real-time PCR were performed on tissue lysate for protein and mRNA expression of p53 and downstream effector proteins, p21, Bax and caspases 3 and 8. To further assess the ability of p53 to modulate apoptosis within trophoblast, BeWo cells and placental villous tissue were exposed to the p53-activator, Nutlin-3, alone or in combination with the p53-inhibitor, Pifithrin-α (PFT-α). Equally, Mdm2 was knocked-down with siRNA.

RESULTS

Protein expression of p53, p21 and Bax was significantly increased in pregnancies complicated by PE. Conversely, Mdm2 protein levels were significantly depleted in PE; immunohistochemistry showed these changes to be confined to trophoblast. Reduction in the negative feedback of p53 by Mdm2, using siRNA and Nutlin-3, caused an imbalance between p53 and Mdm2 that triggered apoptosis in term villous explants. In the case of Nutlin, this was attenuated by Pifithrin-α.

CONCLUSIONS

These data illustrate the potential for an imbalance in p53 and Mdm2 expression to promote excessive apoptosis in villous trophoblast. The upstream regulation of p53 and Mdm2, with regard to exaggerated apoptosis and autophagy in PE, merits further investigation.

Doxorubicin-induced death in tumour cells and cardiomyocytes: is autophagy the key to improving future clinical outcomes?

Objectives

Doxorubicin, a commonly used frontline chemotherapeutic agent for cancer, is not without side-effects. The original thinking that the drug causes necrosis in tumours has largely given way to its link with apoptosis over the past two decades.

Key findings

More recently, major biomarkers such as AMPK, p53 and Bcl-2 have been identified as important to apoptosis induction by doxorubicin. It is Bcl-2 and its interaction with Beclin-1 that has refocussed research attention on doxorubicin, albeit this time for its ability to induce autophagy. Autophagy can be either anticancerous or procancerous however, so it is critical that the reasons for which cancer cells undergo this type of cell biological event be clearly identified for future exploitation.

Summary

Taking a step back from treating patients with large doses of doxorubicin, which causes toxicity to the heart amongst other organs, and further research with this drug's molecular signalling in not only neoplastic but normal cells, may indeed redefine the way doxorubicin is used clinically and potentially lead to better neoplastic disease management.

Role of p53 in Anticancer Drug Treatment- and Radiation-Induced Injury in Normal Small Intestine

In the human gastrointestinal tract, the functional mucosa of the small intestine has the highest capacity for absorption of nutrients and rapid proliferation rates, making it vulnerable to chemoradiotherapy. Recent understanding of the protective role of p53-mediated cell cycle arrest in the small intestinal mucosa has led researchers to explore new avenues to mitigate mucosal injury during cancer treatment. A traditional p53 inhibitor and two other molecules that exhibit strong protective effects on normal small intestinal epithelium during anticancer drug treatment and radiation therapy are introduced in this work. The objective of this review was to update current knowledge regarding potential mechanisms and targets that inhibit the side effects induced by chemoradiotherapy.

BIRC6 protein, an inhibitor of apoptosis: role in survival of human prostate cancer cells

BACKGROUND

BIRC6 is a member of the Inhibitors of Apoptosis Protein (IAP) family which is thought to protect a variety of cancer cells from apoptosis. The main objective of the present study was to investigate whether BIRC6 plays a role in prostate cancer and could be useful as a novel therapeutic target.

METHODS

BIRC6 expression in cell lines was assessed using Western blot analysis and in clinical samples using immunohistochemistry of tissue microarrays. The biological significance of BIRC6 was determined by siRNA-induced reduction of BIRC6 expression in LNCaP cells followed by functional assays.

RESULTS

Elevated BIRC6 protein expression was found in prostate cancer cell lines and clinical specimens as distinct from their benign counterparts. Increased BIRC6 expression was associated with Gleason 6-8 cancers and castration resistance. Reduction of BIRC6 expression in LNCaP cells led to a marked reduction in cell proliferation which was associated with an increase in apoptosis and a decrease in autophagosome formation. Doxorubicin-induced apoptosis was found to be coupled to a reduction in BIRC6 protein expression.

CONCLUSION

The data suggest a role for BIRC6 in prostate cancer progression and treatment resistance, and indicate for the first time that the BIRC6 gene and its product are potentially valuable targets for treatment of prostate cancers.

Cell type-specific effects of Adenosine 5'-triphosphate and pyrophosphate on the antitumor activity of doxorubicin

Extracellular ATP is an important signaling molecule mediating quite divergent specific biological effects. Even though recent studies suggest a potential role of ATP in cancer progress, its real impact in chemotherapeutic efficacy remains unclear. In the present study, we investigated the effect of ATP on the cytotoxicity of doxorubicin in various cancer cell types and found that ATP had no effect on doxorubicin cytotoxicity in colon, prostate, breast, and cervical cancers or in osteosarcoma. In contrast, ATP has divergent effects on lung cancer cells: it can protect against doxorubicin-induced cell death in non-metastatic lung cancer CL1.0 cells, but not in highly metastatic CL1.5 cells. Both apoptotic (characterized by sub-G(1) peak, caspase 3 activation, poly(ADP-ribose) polymerase-1 cleavage) and necrotic (characterized by propidium iodide uptake and ROS production) features induced by doxorubicin in CL1.0 cells were reduced by ATP. In addition, ATP attenuated p53 accumulation, DNA damage (assessed by poly(ADP-ribose) formation and the comet assay) and topoisomerase II inhibition after doxorubicin treatment, and doxorubicin cytotoxicity was diminished by the p53 inhibitor pifithrin-α. Moreover, UTP, UDP, ADP, and pyrophosphate sodium pyrophosphate tetrabasic decahydrate diminished the antitumor effect of doxorubicin in CL1.0 cells, whereas purinergic P2 receptors antagonists did not abrogate the action of ATP. In summary, ATP fails to alter the antitumor efficacy of doxorubicin in most cancer cell types, except in CL1.0 cells, in which pyrophosphate mediates the cell protection afforded by ATP via attenuation of reactive oxygen species production, DNA damage, p53 accumulation, and caspase activation.

Activation of coagulation by a thalidomide-based regimen

Combining thalidomide (Thal) with chemotherapeutic agents or steroid preparations led to improved response rates in the treatment of multiple myeloma. However, deep vein thrombosis (DVT) is one of the most serious side-effects noted with this regimen, and how a Thal-based regimen causes DVT is unclear. We investigated the procoagulant effects of Thal when combined with chemotherapeutic agents in vitro, focusing on tissue factor (TF) and phosphatidylserine. We examined the effects of the chemotherapeutic doxorubicin hydrochloride (Dox) and the steroid dexamethasone (Dex), with or without Thal. Our study used the human vascular endothelial, monocytic, and myeloma cell lines, EAhy926, THP-1, and RPMI8226, respectively. In EAhy926 and THP-1, Dex treatment increased expression of TF, which may induce procoagulant activity (PCA). Upregulation of TF mRNA correlated with activation of the Egr-1 pathway. In Thal and Dex treatments, the increase of PCA induction from phosphatidylserine exposure was modest. In contrast, Dox and Thal-Dox increased phosphatidylserine exposure in both cell types. In THP-1 cells, cell surface phosphatidylserine exposure correlated with increased PCA by Dox. Thal alone showed a modest increase in phosphatidylserine exposure in endothelial cells and monocytes. When Thal is given in combination with chemotherapies or Dex, endothelial cell and monocyte PCA may be induced through phosphatidylserine exposure, or TF expression. Induction may be protracted by Thal, which has an antiangiogenic activity. Therefore, prophylactic anticoagulant strategies should be considered in Thal-based combination regimens.

Monocyte chemoattractant protein-1 induces endothelial cell apoptosis in vitro through a p53-dependent mitochondrial pathway

The cystine-cystine (CC) chemokine monocyte chemoattractant protein-1 (MCP-1) has been established playing a pathogenic role in the development of atherosclerosis due to its chemotactic ability of leading monocytes to locate to subendothelia. Recent studies have revealed more MCP-1 functions other than chemotaxis. Here we reported that various concentrations (0.1-100 ng/ml) of MCP-1 induced human umbilical vein endothelial cell (HUVEC) strain CRL-1730 apoptosis, caspase-9 activation, and a couple of mitochondrial alterations. Moreover, MCP-1 upregulated p53 expression of HUVECs and the p53-specific inhibitor pifithrin-α (PFTα) rescued the MCP-1-induced apoptosis of HUVECs. Furthermore, PKC (protein kinase C) activation or inhibition might also affect HUVECs apoptosis induced by MCP-1. These findings together demonstrate that MCP-1 exerts direct proapoptotic effects on HUVECs in vitro via a p53-dependent mitochondrial pathway.

Silica nanorattle-doxorubicin-anchored mesenchymal stem cells for tumor-tropic therapy

Low targeting efficiency is one of the biggest limitations for nanoparticulate drug delivery system-based cancer therapy. In this study, an efficient approach for tumor-targeted drug delivery was developed with mesenchymal stem cells as the targeting vehicle and a silica nanorattle as the drug carrier. A silica nanorattle-doxorubicin drug delivery system was efficiently anchored to mesenchymal stem cells (MSCs) by specific antibody-antigen recognitions at the cytomembrane interface without any cell preconditioning. Up to 1500 nanoparticles were uploaded to each MSC cell with high cell viability and tumor-tropic ability. The intracellular retention time of the silica nanorattle was no less than 48 h, which is sufficient for cell-directed tumor-tropic delivery. In vivo experiments proved that the burdened MSCs can track down the U251 glioma tumor cells more efficiently and deliver doxorubicin with wider distribution and longer retention lifetime in tumor tissues compared with free DOX and silica nanorattle-encapsulated DOX. The increased and prolonged DOX intratumoral distribution further contributed to significantly enhanced tumor-cell apoptosis. This strategy has potential to be developed as a robust and generalizable method for targeted tumor therapy with high efficiency and low systematic toxicity.