Methotrexate induces apoptosis through p53/p21-dependent pathway and increases E-cadherin expression through downregulation of HDAC/EZH2

A Novel Class I HDAC Inhibitor, AW01178, Inhibits Epithelial-Mesenchymal Transition and Metastasis of Breast Cancer

Epithelial-mesenchymal transition (EMT) refers to the transformation of polar epithelial cells into motile mesenchymal cells under specific physiological or pathological conditions, thus promoting the metastasis of cancer cells. Epithelial cadherin (E-cadherin) is a protein that plays an important role in the acquisition of tumor cell motility and serves as a key EMT epithelial marker. In the present study, AW01178, a small-molecule compound with potential therapeutic efficacy, was identified via in-cell Western high-throughput screening technology using E-cadherin as the target. The compound induced the upregulation of E-cadherin at both mRNA and protein levels and inhibited the EMT of breast cancer cells in vitro as well as metastasis in vivo. Mechanistically, AW01178 is a novel benzacetamide histone deacetylase inhibitor (HDACi) mainly targeting class I histone deacetylases. AW01178 promoted the transcription and expression of E-cadherin through enhancing the acetylation level of histone H3 in the E-cadherin promoter region, thereby inhibiting the metastasis of breast cancer cells. The collective findings support the potential utility of the novel HDACi compound identified in this study, AW01178, as a therapeutic drug for breast cancer and highlight its value for the future development of HDACi structures as anticancer drugs.

Designing a novel drug-drug conjugate as a prodrug for breast cancer therapy: in silico insights

Breast cancer (BC) poses a significant global health threat, necessitating innovative therapeutic approaches. The ribosomal s6 kinase 2 (RSK2) has emerged as a promising target due to its roles in cell proliferation and survival. This study proposes a drug-drug conjugate prodrug comprising Methotrexate (hydrophobic) and Capecitabine (hydrophilic) for BC treatment. In silico approaches, including Molecular Docking, Molecular Dynamics Simulations, MM-PBSA, ADME, and DFT calculations were employed to evaluate the prodrug's potential. The designed MET-CAP ligand exhibits a robust docking score (-8.980 kcal/mol), superior binding affinity (-53.16 kcal/mol), and stable dynamic behavior (0.62 nm) compared to native ligands. The DFT results reveal intramolecular charge transfer in MET-CAP (HLG = 0.09 eV), indicating its potential as a BC inhibitor. ADME analysis suggests satisfactory pharmaceutically relevant properties. The results indicate that the conjugated MET-CAP ligand exhibits favorable binding characteristics, stability, and pharmaceutically relevant properties, making it a potential RSK2 inhibitor for BC therapy. The multifaceted approach provides insights into binding interactions, stability, and pharmacokinetic properties, laying the foundation for further experimental validation and potential clinical development.

The Protective Effect of Roflumilast Against Acute Hepatotoxicity Caused by Methotrexate in Wistar Rats: In vivo Evaluation

Introduction

Methotrexate (MTX) is one of the most widely used drugs in cancer chemotherapy and treating rheumatoid arthritis. The hepatotoxicity of MTX is one of its major side effects. Roflumilast (ROF) has been recognized to have antioxidant and anti-inflammatory activity in in-vivo and in-vitro models. The present study aimed to explore the potential protective effects of roflumilast against MTX-induced liver toxicity in male Wistar rats.

Methods

High dose of 5 mg/kg for 4 consecutive days subcutaneous (S.C) injection of methotrexate for induction of acute liver injury. A total of 24 Wistar rats, rats were used in four different groups. The NS injections were given S.C to the control group once a day for 4 consecutive days. SC injections of MTX (5 mg/kg) were given to the MTX group daily for four days. At 5 mg/kg once daily for four days, the roflumilast group was given daily oral roflumilast. An injection of MTX and oral roflumilast were given to the MTX + roflumilast group once daily for four consecutive days.

Results

Administration of high dose MTX (5 mg/kg) today 4 produced a significant decrease in hepatic glutathione (GSH) levels and a significant increase in ALT and AST liver enzymes, hepatic malondialdehyde (MDA), tumor suppressor protein (p53), interleukin 6, interleukin 1 levels compared to the control group. Treatment with roflumilast for 4 days significantly attenuated unfavorable changes in these parameters. According to histopathological findings, Roflumilast significantly reduced MTX-induced inflammation and degeneration in the liver. In conclusion, the findings indicate that roflumilast may have a potential therapeutic benefit in treating rats with MTX-induced liver toxicity by mitigating its effects.

Purpose

The aim of this study is to investigate the potential protective effects of roflumilast against MTX-induced liver toxicity in Wistar rats.

Synthesis and characterization of bis-amide SSE1917 as a microtubule-stabilizing anticancer agent

Microtubule dynamics are critical for spindle assembly and chromosome segregation during cell division. Pharmacological inhibition of microtubule dynamics in cells causes prolonged mitotic arrest, resulting in apoptosis, an approach extensively employed in treating different types of cancers. The present study reports the synthesis of thirty-two novel bis-amides (SSE1901-SSE1932) and the evaluation of their antiproliferative activities. N-(1-oxo-3-phenyl-1-(phenylamino)propan-2-yl)benzamide (SSE1917) exhibited the most potent activity with GI50 values of 0.331 ± 0.01 µM in HCT116 colorectal and 0.48 ± 0.27 µM in BT-549 breast cancer cells. SSE1917 stabilized microtubules in biochemical and cellular assays, bound to taxol site in docking studies, and caused aberrant mitosis and G2/M arrest in cells. Prolonged treatment of cells with the compound increased p53 expression and triggered apoptotic cell death. Furthermore, SSE1917 suppressed the growth of both mouse and patient-derived human colon cancer organoids, highlighting its potential therapeutic value as an anticancer agent.

Differential Benefit of Metronomic Chemotherapy Among Triple-Negative Breast Cancer Subtypes Treated in the IBCSG Trial 22-00

PURPOSE

To explore whether specific triple-negative breast cancer (TNBC) molecular subtypes are predictive for a benefit from maintenance low-dose cyclophosphamide and methotrexate (CM) in the adjuvant IBCSG 22-00 phase III clinical trial.

EXPERIMENTAL DESIGN

RNA sequencing was performed on a selection of 347 TNBC formalin-fixed paraffin-embedded (FFPE) tumor samples following a case-cohort-like sampling. TNBC subtypes were computed on gene expression data. The association between TNBC subtypes and treatment outcome was assessed using a Cox proportional-hazards interaction test.

RESULTS

Immunomodulatory (IM) and basal-like/immune activated (BLIA) molecular subtypes showed a significant survival benefit when treated with low-dose CM [disease-free survival (DFS): HR, 0.5; 95% confidence interval (CI), 0.28-0.89; Pinteraction = 0.018 and HR, 0.49; 95% CI, 0.27-0.9; Pinteraction = 0.021]. Moreover, a high expression of regulatory T-cell immune signature was associated with a better prognosis in the CM arm, in line with a potential immunomodulating role of cyclophosphamide. In contrast, a worse outcome was observed in tumors with a mesenchymal (M) subtype treated with low-dose CM (DFS: HR, 1.9; 95% CI, 1.2-3; Pinteraction = 0.0044).

CONCLUSIONS

Our results show a differential benefit of low-dose CM therapy across different TNBC subtypes. Low-dose CM therapy could be considered as a potential strategy for TNBC tumors with IM subtype in the early-disease setting.

Hypoxia-mediated promotion of glucose metabolism in non-small cell lung cancer correlates with activation of the EZH2/FBXL7/PFKFB4 axis

F-box/LRR-repeat protein 7 (FBXL7) was predicted as a differentially expressed E3 ubiquitin ligase in non-small cell lung cancer (NSCLC), which has been suggested to influence cancer growth and metastasis. In this study, we aimed to decipher the function of FBXL7 in NSCLC and delineate the upstream and downstream mechanisms. FBXL7 expression was verified in NSCLC cell lines and GEPIA-based tissue samples, after which the upstream transcription factor of FBXL7 was bioinformatically identified. The substrate PFKFB4 of the FBXL7 was screened out by tandem affinity purification coupled with mass-spectrometry (TAP/MS). FBXL7 was downregulated in NSCLC cell lines and tissue samples. FBXL7 ubiquitinated and degraded PFKFB4, thus suppressing glucose metabolism and malignant phenotypes of NSCLC cells. Hypoxia-induced HIF-1α upregulation elevated EZH2 and inhibited FBXL7 transcription and reduced its expression, thus promoting PFKFB4 protein stability. By this mechanism, glucose metabolism and the malignant phenotype were enhanced. In addition, knockdown of EZH2 impeded tumor growth through the FBXL7/PFKFB4 axis. In conclusion, our work reveals that the EZH2/FBXL7/PFKFB4 axis plays a regulatory role in glucose metabolism and tumor growth of NSCLC, which is expected to be potential biomarkers for NSCLC.

Reverse tracking from drug-induced transcriptomes through multilayer molecular networks reveals hidden drug targets

Identifying molecular targets of a drug is an essential process for drug discovery and development. The recent in-silico approaches are usually based on the structure information of chemicals and proteins. However, 3D structure information is hard to obtain and machine-learning methods using 2D structure suffer from data imbalance problem. Here, we present a reverse tracking method from genes to target proteins using drug-perturbed gene transcriptional profiles and multilayer molecular networks. We scored how well the protein explains gene expression changes perturbed by a drug. We validated the protein scores of our method in predicting known targets of drugs. Our method performs better than other methods using the gene transcriptional profiles and shows the ability to suggest the molecular mechanism of drugs. Furthermore, our method has the potential to predict targets for objects that do not have rigid structural information, such as coronavirus.

Systems Drug Discovery for Diffuse Large B Cell Lymphoma Based on Pathogenic Molecular Mechanism via Big Data Mining and Deep Learning Method

Diffuse large B cell lymphoma (DLBCL) is an aggressive heterogeneous disease. The most common subtypes of DLBCL include germinal center b-cell (GCB) type and activated b-cell (ABC) type. To learn more about the pathogenesis of two DLBCL subtypes (i.e., DLBCL ABC and DLBCL GCB), we firstly construct a candidate genome-wide genetic and epigenetic network (GWGEN) by big database mining. With the help of two DLBCL subtypes’ genome-wide microarray data, we identify their real GWGENs via system identification and model order selection approaches. Afterword, the core GWGENs of two DLBCL subtypes could be extracted from real GWGENs by principal network projection (PNP) method. By comparing core signaling pathways and investigating pathogenic mechanisms, we are able to identify pathogenic biomarkers as drug targets for DLBCL ABC and DLBCL GCD, respectively. Furthermore, we do drug discovery considering drug-target interaction ability, drug regulation ability, and drug toxicity. Among them, a deep neural network (DNN)-based drug-target interaction (DTI) model is trained in advance to predict potential drug candidates holding higher probability to interact with identified biomarkers. Consequently, two drug combinations are proposed to alleviate DLBCL ABC and DLBCL GCB, respectively.

Protective Effect of Pycnogenol against Methotrexate-Induced Hepatic, Renal, and Cardiac Toxicity: An In Vivo Study

Methotrexate (MTX) is one of the most commonly used chemotherapies for various types of cancer, including leukemia, breast cancer, hepatocarcinoma, and gastric cancers. However, the efficacy of MTX is frequently limited by serious side effects. Several studies have reported that the cytotoxic effect of MTX is not limited to cancer cells but can also affect normal tissues, leading to prospective damage to many organs. In the present study, we extensively investigated the molecular and microscopic basis of MTX-induced toxicity in different organs (liver, kidney, and heart) and explored the possible protective effect of pycnogenol, a polyphenolic component extracted from the bark of P. pinaster, to attenuate these effects. Biochemical analysis revealed that administration of MTX significantly reduced the function of the liver, kidney, and heart. Histological and immunohistochemical analysis indicated that MTX treatment caused damage to tissues of different organs. Interestingly, administration of pycnogenol (10, 20, and 30 mg/kg) significantly attenuated the deterioration effects of MTX on different organs in a dose-dependent manner, as demonstrated by biochemical and histological analysis. Our results reveal that pycnogenol successfully ameliorated oxidative damage and reduced toxicity, inflammatory response, and histological markers induced by methotrexate treatment. Taken together, this study provides solid evidence for the pharmacological application of pycnogenol to attenuate damage to different organs induced by MTX treatment.

Vitamin-Containing Antioxidant Formulation Reduces Carcinogen-Induced DNA Damage through ATR/Chk1 Signaling in Bronchial Epithelial Cells In Vitro

Lung cancer has the highest mortality rate worldwide and is often diagnosed at late stages, requiring genotoxic chemotherapy with significant side effects. Cancer prevention has become a major focus, including the use of dietary and supplemental antioxidants. Thus, we investigated the ability of an antioxidant formulation (AOX1) to reduce DNA damage in human bronchial epithelial cells (BEAS-2B) with and without the combination of apple peel flavonoid fraction (AF4), or its major constituent quercetin (Q), or Q-3-O-d-glucoside (Q3G) in vitro. To model smoke-related genotoxicity, we used cigarette-smoke hydrocarbon 4-[(acetoxymethyl)nitrosamino]-1-(3-pyridyl)-1-butanone (NNKOAc) as well as methotrexate (MTX) to induce DNA damage in BEAS-2B cells. DNA fragmentation, γ-H2AX immunofluorescence, and comet assays were used as indicators of DNA damage. Pre-exposure to AOX1 alone or in combination with AF4, Q, or Q3G before challenging with NNKOAc and MTX significantly reduced intracellular reactive oxygen species (ROS) levels and DNA damage in BEAS-2B cells. Although NNKOAc-induced DNA damage activated ATM-Rad3-related (ATR) and Chk1 kinase in BEAS-2B cells, pre-exposure of the cells with tested antioxidants prior to carcinogen challenge significantly reduced their activation and levels of γ-H2AX (p ≤ 0.05). Therefore, AOX1 alone or combined with flavonoids holds promise as a chemoprotectant by reducing ROS and DNA damage to attenuate activation of ATR kinase following carcinogen exposure.

Overview of Evidence-Based Chemotherapy for Oral Cancer: Focus on Drug Resistance Related to the Epithelial-Mesenchymal Transition

The increasing incidence of resistance to chemotherapeutic agents has become a major issue in the treatment of oral cancer (OC). Epithelial-mesenchymal transition (EMT) has attracted a great deal of attention in recent years with regard to its relation to the mechanism of chemotherapy drug resistance. EMT-activating transcription factors (EMT-ATFs), such as Snail, TWIST, and ZEB, can activate several different molecular pathways, e.g., PI3K/AKT, NF-κB, and TGF-β. In contrast, the activated oncological signal pathways provide reciprocal feedback that affects the expression of EMT-ATFs, resulting in a peritumoral extracellular environment conducive to cancer cell survival and evasion of the immune system, leading to resistance to multiple chemotherapeutic agents. We present an overview of evidence-based chemotherapy for OC treatment based on the National Comprehensive Cancer Network (NCCN) Chemotherapy Order Templates. We focus on the molecular pathways involved in drug resistance related to the EMT and highlight the signal pathways and transcription factors that may be important for EMT-regulated drug resistance. Rapid progress in antitumor regimens, together with the application of powerful techniques such as high-throughput screening and microRNA technology, will facilitate the development of therapeutic strategies to augment chemotherapy.

Modeling drug response using network-based personalized treatment prediction (NetPTP) with applications to inflammatory bowel disease

For many prevalent complex diseases, treatment regimens are frequently ineffective. For example, despite multiple available immunomodulators and immunosuppressants, inflammatory bowel disease (IBD) remains difficult to treat. Heterogeneity in the disease across patients makes it challenging to select the optimal treatment regimens, and some patients do not respond to any of the existing treatment choices. Drug repurposing strategies for IBD have had limited clinical success and have not typically offered individualized patient-level treatment recommendations. In this work, we present NetPTP, a Network-based Personalized Treatment Prediction framework which models measured drug effects from gene expression data and applies them to patient samples to generate personalized ranked treatment lists. To accomplish this, we combine publicly available network, drug target, and drug effect data to generate treatment rankings using patient data. These ranked lists can then be used to prioritize existing treatments and discover new therapies for individual patients. We demonstrate how NetPTP captures and models drug effects, and we apply our framework to individual IBD samples to provide novel insights into IBD treatment.

Offering personalized treatment results is an important tenant of precision medicine, particularly in complex diseases which have high variability in disease manifestation and treatment response. We have developed a novel framework, NetPTP (Network-based Personalized Treatment Prediction), for making personalized drug ranking lists for patient samples. Our method uses networks to model drug effects from gene expression data and applies these captured effects to individual samples to produce tailored drug treatment rankings. We applied NetPTP to inflammatory bowel disease, yielding insights into the treatment of this particular disease. Our method is modular and generalizable, and thus can be applied to other diseases that could benefit from a personalized treatment approach.

Nanoparticles Incorporating a Fluorescence Turn-on Reporter for Real-Time Drug Release Monitoring, a Chemoenhancer and a Stealth Agent: Poseidon's Trident against Cancer?

The rate and extent of drug release under physiological conditions is a key factor influencing the therapeutic activity of a formulation. Real-time detection of drug release by conventional pharmacokinetics approaches is confounded by low sensitivity, particularly in the case of tissue-targeted novel drug delivery systems, where low concentrations of the drug reach systemic circulation. We present a novel fluorescence turn-on platform for real-time monitoring of drug release from nanoparticles based on reversible fluorescence quenching in fluorescein esters. Fluorescein-conjugated carbon nanotubes (CNTs) were esterified with methotrexate in solution and solid phase, followed by supramolecular functionalization with a chemoenhancer (suramin) or/and a stealth agent (dextran sulfate). Suramin was found to increase the cytotoxicity of methotrexate in A549 cells. On the other hand, dextran sulfate exhibited no effect on cytotoxicity or cellular uptake of CNTs by A549 cells, while a decrease in cellular uptake of CNTs and cytotoxicity of methotrexate was observed in macrophages (RAW 264.7 cells). Similar results were also obtained when CNTs were replaced with graphene. Docking studies revealed that the conjugates are not internalized by folate receptors/transporters. Further, docking and molecular dynamics studies revealed the conjugates do not exhibit affinity toward the methotrexate target, dihydrofolate reductase. Molecular dynamics studies also revealed that distinct features of dextran-CNT and suramin-CNT interactions, characterized by π-π interactions between CNTs and dextran/suramin. Our study provides a simple, cost-effective, and scalable method for the synthesis of nanoparticles conferred with the ability to monitor drug release in real-time. This method could also be extended to other drugs and other types of nanoparticles.

CDKN1A upregulation and cisplatin‑pemetrexed resistance in non‑small cell lung cancer cells

Cisplatin-pemetrexed is a frequently adopted first-line treatment for patients with advanced non-small cell lung cancer (NSCLC) ineligible for biological therapy, notwithstanding its limited efficacy. In the present study, the RAL cell line, an epidermal growth factor receptor (EGFR)-wild-type, p53- and KRAS-mutated model of NSCLC, was used to investigate novel biomarkers of resistance to this treatment. Cells were analyzed 96 h (96 h-post wo) and 21 days (21 days-post wo) after the combined treatment washout. Following an initial moderate sensitivity to the treatment, the cell growth proliferative capability had fully recovered. Gene expression analysis of the resistant surviving cells revealed a significant upregulation of CDKN1A expression in the cells at 96-h post-wo and, although to a lesser extent, in the cells at 21 days-post wo, accompanied by an enrichment of acetylated histone H3 in its promoter region. CDKN1A was also upregulated at the protein level, being mainly detected in the cytoplasm of the cells at 96 h-post wo. A marked increase in the number of apoptotic cells, together with a significant G1 phase block, were observed at 96-h post wo in the cells in which CDKN1A was knocked down, suggesting its involvement in the modulation of the response of RAL cells to the drug combination. On the whole, these data suggest that CDKN1A plays a role in the response to the cisplatin-pemetrexed combination in advanced KRAS-mutated NSCLC, thus suggesting that it may be used as a promising predictive marker.

Toxic Effects of Methotrexate on Rat Kidney Recovered by Crocin as a Consequence of Antioxidant Activity and Lipid Peroxidation Prevention

Background

The application of methotrexate (MTX) as a chemotherapy agent and immune system suppressant has various side effects. Crocin, a xanthine derivative plant, has many therapeutic benefits. This study was planned to assess the effect of crocin on renal toxicity of MTX in a rat model.

Methods

Forty eight rats were divided randomly into eight groups (n = 6), which received normal saline, MTX, crocin, and MTX + crocin for 28 days intraperitoneally. The levels of oxidative stress in kidney and blood serum were measured, and the kidney was analyzed histologically.

Results

MTX caused an enhancement in the levels of thiobarbituric acid reactive substances and biochemical marker (creatinine and BUN). Besides, a significant decrease was observed in tissue parameters and antioxidant capacity compared to the normal control group (p < 0.001). The crocin and crocin + MTX decreased the biochemical markers, the levels of thiobarbituric acid reactive species, and tissue parameters considerably at entire dose (12.5, 25, and 50 mg/kg) and enhanced the antioxidant capacity levels compared to the MTX group (p < 0.001).

Conclusion

Administration of crocin improves the damage caused by MTX in rats. The crocin by the establishment of balance in the levels of antioxidant prevents the damage to the renal cell membrane, and subsequently the renal damage repairs.

The possible role of heat shock protein-70 induction in collagen-induced arthritis in rats

AIM

This study aimed to evaluate the possible role of heat shock protein-70 (HSP70) induction by 17-allylaminodemethoxygeldanamycin (17-AAG) in collagen-induced arthritis in rats.

MATERIAL AND METHODS

Male Wistar rats were divided into five groups (n = 10/group) and were treated intraperitoneally twice a week for 4 weeks, namely normal control (saline), arthritis control (AR; saline), AR + 17-AAG, AR + methotrexate (MTX), and AR + 17-AAG + MTX. At the end of the treatments, arthritic score was determined and then the animals were sacrificed. Erythrocyte sedimentation rate (ESR), serum levels of HSP70, interleukin-17 (IL-17), tumor necrosis factor-alpha (TNF-α), rheumatic factor (RF), C-reactive protein (CRP), malondialdehyde (MDA), glutathione peroxidase (GPx), and matrix metalloproteinase-9 (MMP-9) were determined.

RESULTS

In the AR group, all parameters increased significantly, except for GPx, which showed a pronounced decrease. The 17-AAG and/or MTX treatments significantly reduced arthritic score, ESR, IL-17, TNF-α, RF, CRP, MDA, and MMP-9 with significant increase in GPx compared to the AR group. The HSP70 level was significantly higher in the AR + 17-AAG and the AR + 17-AAG + MTX groups but significantly lower in the AR + MTX group as compared to the AR group. Also, it was significantly lower in the AR + MTX group as compared to the AR + 17-AAG group.

CONCLUSION

We concluded that HSP70 induction by 17-AAG attenuated the inflammatory process in a rheumatoid arthritis (RA) model induced by collagen, which suggested that HSP70 inducers can be promising agents in the treatment of RA.

Apoptosis: A mammalian cell bioprocessing perspective

Apoptosis is a form of programmed and controlled cell death that accounts for the majority of cellular death in bioprocesses. Cell death affects culture longevity and product quality; it is instigated by several stresses experienced by the cells within a bioreactor. Understanding the factors that cause apoptosis as well as developing strategies that can protect cells is crucial for robust bioprocess development. This review aims to a) address apoptosis from a bioprocess perspective; b) describe the significant apoptotic mechanisms linking them to the most relevant stresses encountered in bioreactors; c) discuss the design of operating conditions in order to avoid cell death; d) focus on industrially relevant cell lines; and e) present anti-apoptosis strategies including cell engineering and model-based optimization of bioprocesses. In addition, the importance of apoptosis in quality-by-design bioprocess development from clone screening to production scale are highlighted.

TAT-mediated intracellular delivery of carboxypeptidase G2 protects against methotrexate-induced cell death in HepG2 cells

Side effects of methotrexate (MTX) especially hepatotoxicity limits clinical applications of this anticancer agent. Carboxypeptidase G2 (CPG2) is administrated for the treatment of elevated plasma concentrations of MTX. In this study, we have investigated the intracellular delivery of CPG2 fused to the transactivator transduction domain (TAT) and its protective effects against MTX-induced cell death of HepG2 cells. We have observed that both native and denatured forms of the enzyme transduced into the HepG2 cells efficiently in a concentration and time-dependent manner. The denatured protein transduced with higher efficiency than the native form and was functional inside the cells. MTX exposure significantly decreased HepG2 cell viability in a dose- and time-dependent manner. The cell viability after 24 and 48 h of incubation with 100 μM MTX was reduced to 44.37% and 17.69%, respectively. In cells pretreated with native and denatured TAT-CPG2 protein the cell viability was 98.63% and 86.31% after 24 and 48 h, respectively. Treatment with MTX increased the number of apoptotic HepG2 cells to 90.23% after 48 h. However, the apoptosis percentage in cells pretreated with native and denatured TAT-CPG2 was 21.49% and 22.28%, respectively. Our results showed that TAT-CPG2 significantly prevents MTX-induced oxidative stress by decreasing the formation of ROS and increasing the content of glutathione (GSH) and catalase activity. Our finding indicates that both native and denatured TAT-CPG2 strongly protect HepG2 cells against MTX-induced oxidative stress and apoptosis. Hence, intracellular delivery of CPG2 might provide a new therapeutic strategy for protecting against MTX mediated cytotoxicity.

Novel DOX-MTX nanoparticles improve oral SCC clinical outcome by down regulation of lymph dissemination factor VEGF-C expression in vivo: oral and IV modalities

BACKGROUND

Oral squamous cell carcinoma (OSCC) remains as one of the most difficult malignancies to control because of its high propensity for local invasion and cervical lymph node dissemination. The aim of present study was to evaluate the efficacy of novel pH and temperature sensitive doxorubicin-methotrexate- loaded nanoparticles (DOX-MTX NP) in terms of their potential to change the VEGF-C expression profile in a rat OSCC model.

MATERIALS AND METHODS

120 male rats were divided into 8 groups of 15 animals administrated with 4-nitroquinoline-1-oxide to induce OSCCs. Newly formulated doxorubicin-methotrexate-loaded nanoparticles (DOX-MTX NP) and free doxorubicin were IV and orally administered.

RESULTS

RESULTS indicated that both oral and IV forms of DOX-MTX- nanoparticle complexes caused significant decrease in the mRNA level of VEGF-C compared to untreated cancerous rats (p<0.05) . Surprisingly, the VEGF-C mRNA was not affected by free DOX in both IV and oral modalities (p>0.05). Furthermore, in DOX-MTX NP treated group, less tumors characterized with advanced stage and VEGF-C mRNA level paralleled with improved clinical outcome (p<0.05). In addition, compared to untreated healthy rats , the VEGF-C expression was not affected in healthy groups that were treated with IV and oral dosages of nanodrug (p>0.05).

CONCLUSIONS

VEGF-C is one of the main prognosticators for lymph node metastasis in OSCC. Down-regulation of this lymph-angiogenesis promoting factor is a new feature acquired in group treated with dual action DOX-MTX-NPs. Beside the synergic apoptotic properties of concomitant use of DOX and MTX on OSCC, DOX-MTX NPs possessed anti-angiogenesis properties which was related to the improved clinical outcome in treated rats. Taking together, we conclude that our multifunctional doxorubicin-methotrexate complex exerts specific potent apoptotic and anti-angiogenesis properties that could ameliorate the clinical outcome presumably via down-regulating dissemination factor-VEGF-C expression in a rat OSCC model.

Apoptosis Induction and Gene Expression Profile Alterations of Cutaneous T-Cell Lymphoma Cells following Their Exposure to Bortezomib and Methotrexate

Mycosis fungoides (MF) and its leukemic variant Sézary syndrome (SS) comprise the majority of CTCL, a heterogenous group of non-Hodgkins lymphomas involving the skin. The CTCL’s resistance to chemotherapy and the lack of full understanding of their pathogenesis request further investigation. With the view of a more targeted therapy, we evaluated in vitro the effectiveness of bortezomib and methotrexate, as well as their combination in CTCL cell lines, regarding apoptosis induction. Our data are of clinical value and indicate that the bortezomib/methotrexate combinational therapy has an inferior impact on the apoptosis of CTCL compared to monotherapy, with bortezomib presenting as the most efficient treatment option for SS and methotrexate for MF. Using PCR arrays technology, we also investigated the alterations in the expression profile of genes related to DNA repair pathways in CTCL cell lines after treatment with bortezomib or methotrexate. We found that both agents, but mostly bortezomib, significantly deregulate a large number of genes in SS and MF cell lines, suggesting another pathway through which these agents could induce apoptosis in CTCL. Finally, we show that SS and MF respond differently to treatment, verifying their distinct nature and further emphasizing the need for discrete treatment approaches.

Much more than you expected: The non-DHFR-mediated effects of methotrexate

BACKGROUND

For decades, methotrexate (MTX; amethopterin) has been known as an antifolate inhibitor of dihydrofolate reductase (DHFR), and it is widely used for the treatment of various malignancies and autoimmune diseases. Although the inclusion of MTX in various therapeutic regimens is based on its ability to inhibit DHFR and consequently to suppress the synthesis of pyrimidine and purine precursors, recent studies have shown that MTX is also able to target other intracellular pathways that are independent of folate metabolism.

SCOPE OF REVIEW

The main aim of this review is to summarize the most important, up-to-date findings of studies regarding the non-DHFR-mediated mechanisms of MTX action.

MAJOR CONCLUSIONS

The effectiveness of MTX is undoubtedly caused by its capability to affect various intracellular pathways at many levels. Although the most important therapeutic mechanism of MTX is strongly based on the inhibition of DHFR, many other effects of this compound have been described and new studies bring new insights into the pharmacology of MTX every year.

GENERAL SIGNIFICANCE

Identification of these new targets for MTX is especially important for a better understanding of MTX action in new protocols of combination therapy.

Methotrexate induces DNA damage and inhibits homologous recombination repair in choriocarcinoma cells

OBJECTIVE

The objective of this study was to investigate the mechanism of sensitivity to methotrexate (MTX) in human choriocarcinoma cells regarding DNA damage response.

METHODS

Two choriocarcinoma cancer cell lines, JAR and JEG-3, were utilized in this study. An MTX-sensitive osteosarcoma cell line MG63, an MTX-resistant epithelial ovarian cancer cell line A2780 and an MTX-resistant cervical adenocarcinoma cell line Hela served as controls. Cell viability assay was carried out to assess MTX sensitivity of cell lines. MTX-induced DNA damage was evaluated by comet assay. Quantitative reverse transcription polymerase chain reaction was used to detect the mRNA levels of BRCA1, BRCA2, RAD51 and RAD52. The protein levels of γH2AX, RAD 51 and p53 were analyzed by Western blot.

RESULTS

Remarkable DNA strand breaks were observed in MTX-sensitive cell lines (JAR, JEG-3 and MG63) but not in MTX-resistant cancer cells (A2780 and Hela) after 48 h of MTX treatment. Only in the choriocarcinoma cells, the expression of homologous recombination (HR) repair gene RAD51 was dramatically suppressed by MTX in a dose- and time-dependent manner, accompanied with the increase in p53.

CONCLUSION

The MTX-induced DNA strand breaks accompanied by deficiencies in HR repair may contribute to the hypersensitivity to chemotherapy in choriocarcinoma.

One-Carbon Metabolism in Prostate Cancer: The Role of Androgen Signaling

Cancer cell metabolism differs significantly from the metabolism of non-transformed cells. This altered metabolic reprogramming mediates changes in the uptake and use of nutrients that permit high rates of proliferation, growth, and survival. The androgen receptor (AR) plays an essential role in the establishment and progression of prostate cancer (PCa), and in the metabolic adaptation that takes place during this progression. In its role as a transcription factor, the AR directly affects the expression of several effectors and regulators of essential catabolic and biosynthetic pathways. Indirectly, as a modulator of the one-carbon metabolism, the AR can affect epigenetic processes, DNA metabolism, and redox balance, all of which are important factors in tumorigenesis. In this review, we focus on the role of AR-signaling on one-carbon metabolism in tumorigenesis. Clinical implications of one-carbon metabolism and AR-targeted therapies for PCa are discussed in this context.

Perturbation Detection Through Modeling of Gene Expression on a Latent Biological Pathway Network: A Bayesian hierarchical approach

Cellular response to a perturbation is the result of a dynamic system of biological variables linked in a complex network. A major challenge in drug and disease studies is identifying the key factors of a biological network that are essential in determining the cell's fate. Here our goal is the identification of perturbed pathways from high-throughput gene expression data. We develop a three-level hierarchical model, where (i) the first level captures the relationship between gene expression and biological pathways using confirmatory factor analysis, (ii) the second level models the behavior within an underlying network of pathways induced by an unknown perturbation using a conditional autoregressive model, and (iii) the third level is a spike-and-slab prior on the perturbations. We then identify perturbations through posterior-based variable selection. We illustrate our approach using gene transcription drug perturbation profiles from the DREAM7 drug sensitivity predication challenge data set. Our proposed method identified regulatory pathways that are known to play a causative role and that were not readily resolved using gene set enrichment analysis or exploratory factor models. Simulation results are presented assessing the performance of this model relative to a network-free variant and its robustness to inaccuracies in biological databases.

Targeting EZH2 for cancer therapy: progress and perspective

Enhancer of Zeste Homolog 2 (EZH2) is the core component of the polycomb repressive complex 2 (PRC2), possessing the enzymatic activity in generating di/tri-methylated lysine 27 in histone H3. EZH2 has important roles during early development, and its dysregulation is heavily linked to oncogenesis in various tissue types. Accumulating evidences suggest a remarkable therapeutic potential by targeting EZH2 in cancer cells. The first part reviews current strategies to target EZH2 in cancers, and evaluates the available compounds and agents used to disrupt EZH2 functions. Then we provide insight to the future direction of the research on targeting EZH2 in different cancer types. We comprehensively discuss the current understandings of the 1) structure and biological activity of EZH2, 2) its role during the assembling of PRC2 and recruitment of other protein components, 3) the molecular events directing EZH2 to target genomic regions, and 4) post-translational modification at EZH2 protein. The discussion provides the basis to inspire the development of novel strategies to abolish EZH2-related effects in cancer cells.

Ceramide Synthase 6 Is a Novel Target of Methotrexate Mediating Its Antiproliferative Effect in a p53-Dependent Manner

We previously reported that ceramide synthase 6 (CerS6) is elevated in response to folate stress in cancer cells, leading to enhanced production of C₁₆-ceramide and apoptosis. Antifolate methotrexate (MTX), a drug commonly used in chemotherapy of several types of cancer, is a strong inhibitor of folate metabolism. Here we investigated whether this drug targets CerS6. We observed that CerS6 protein was markedly elevated in several cancer cell lines treated with MTX. In agreement with the enzyme elevation, its product C₁₆-ceramide was also strongly elevated, so as several other ceramide species. The increase in C₁₆-ceramide, however, was eliminated in MTX-treated cells lacking CerS6 through siRNA silencing, while the increase in other ceramides sustained. Furthermore, the siRNA silencing of CerS6 robustly protected A549 lung adenocarcinoma cells from MTX toxicity, while the silencing of another ceramide synthase, CerS4, which was also responsive to folate stress in our previous study, did not interfere with the MTX effect. The rescue effect of CerS6 silencing upon MTX treatment was further confirmed in HCT116 and HepG2 cell lines. Interestingly, CerS6 itself, but not CerS4, induced strong antiproliferative effect in several cancer cell lines if elevated by transient transfection. The effect of MTX on CerS6 elevation was likely p53 dependent, which is in agreement with the hypothesis that the protein is a transcriptional target of p53. In line with this notion, lometrexol, the antifolate inducing cytotoxicity through the p53-independent mechanism, did not affect CerS6 levels. We have also found that MTX induces the formation of ER aggregates, enriched with CerS6 protein. We further demonstrated that such aggregation requires CerS6 and suggests that it is an indication of ER stress. Overall, our study identified CerS6 and ceramide pathways as a novel MTX target.

Cell cycle arrest and apoptosis induced by aspidin PB through the p53/p21 and mitochondria-dependent pathways in human osteosarcoma cells

Aspidin PB is a natural product extracted from Dryopteris fragrans (L.) Schott, which has been characterized for its various biological activities. We reported that aspidin PB induced cell cycle arrest and apoptosis through the p53/p21 and mitochondria-dependent pathways in human osteosarcoma cells. Aspidin PB inhibited the proliferation of Saos-2, U2OS, and HOS cells in a dose-dependent and time-dependent manner. Aspidin PB induced changes in the cell cycle regulators (cyclin A, pRb, CDK2, p53, and p21), which caused cell cycle arrest in the S phase. We also explored the role of siRNA targeted to p53; it led to a dose-dependent attenuation of aspidin PB-induced apoptosis signaling. Moreover, after treatment with aspidin PB, the p21-silenced cells decreased significantly at the S phase. Aspidin PB increased the percentage of cells with mitochondrial membrane potential disruption. Western blot analysis showed that aspidin PB inhibited Bcl-2 expression and induced Bax expression to disintegrate the outer mitochondrial membrane and caused cytochrome C release. Mitochondrial cytochrome C release was associated with the activation of caspase-9 and caspase-3 cascades. Furthermore, the double-stranded DNA breaks and reactive oxygen species signaling were both involved in aspidin PB-induced DNA damage. In addition, aspidin PB inhibited tumor growth significantly in U2OS xenografts. Above all, we conclude that aspidin PB represents a valuable natural source and may potentially be applicable in osteosarcoma therapy.

Oral and IV dosages of doxorubicin-methotrexate loaded- nanoparticles inhibit progression of oral cancer by down- regulation of matrix Methaloproteinase 2 expression in vivo

Oral cancer is one of the most common and lethal cancers in the world. Combination chemotherapy coupled with nanoparticle drug delivery holds substantial promise in cancer therapy. This study aimed to evaluate the efficacy and safety of two dosages of our novel pH and temperature sensitive doxorubicin-methotrexate-loaded nanoparticles (DOX-MTX NPs) with attention to the MMP-2 mRNA profile in a 4-nitroquinoline-1-oxide induced oral squamous cell carcinoma (OSCC) model in the rat. Our results showed that both IV and oral dosages of DOX-MTX NP caused significant decrease in mRNA levels of MMP-2 compared to the untreated group (p<0.003). Surprisingly, MMP-2 mRNA was not affected in DOX treated compared to cancer group (p>0.05). Our results indicated that IV dosage of MTX-DOX is more effective than free DOX (12 fold) in inhibiting the activity of MMP-2 in OSCCs (P<0.001). Furthermore, MMP-2 mRNA expression in the DOX-MTX treated group showed a significant relation with histopathological changes (P=0.011). Compared to the untreated cancer group, we observed no pathological changes and neither a significant alteration in MMP-2 amount in either of healthy controls that were treated with oral and IV dosages of DOX-MTX NPs whilst cancer group showed a high level of MMP-2 expression compared to healthy controls (p<0.001).Taking together our results indicate that DOX- MTX NPs is a safe chemotherapeutic nanodrug that its oral and IV forms possess potent anti-cancer properties on aggressive tumors like OSCC, possibly by affecting the expression of genes that drive tumor invasion and metastasis.

New formulated "DOX-MTX-loaded nanoparticles" down- regulate HER2 gene expression and improve the clinical outcome in OSCCs model in rat: the effect of IV and oral modalities

BACKGROUND

Oral squamous cell carcinoma (OSCC) remains as one of the most difficult malignancies to control because of its high propensity for local invasion and cervical lymph node dissemination. In this study, we evaluate the efficacy of our novel pH and temperature sensitive doxorubicin-methotrexate-loaded nanoparticles (DOX-MTX NP) in affecting HER2 expression profile in OSCC model in rat.

RESULTS

DOX-MTX- nanoparticle complexes caused significant decrease in mRNA level of HER2 compared to untreated cancers (p<0.05) and this finding was more pronounced with the IV mode (p<0.000). Surprisingly, HER2 mRNA was not affected in DOX treated as compared to the control group (p>0.05). On the other hand, in the DOX-MTX NP treated group, fewer tumors characterized with advanced stage and decreased HER2 paralleled improved clinical outcome (P<0.05). Moreover, the effectiveness of the oral route in the group treated with nanodrug accounted for the enhanced bioavailability of nanoparticulated DOX-MTX compared to free DOX. Furthermore, there was no significant difference in mRNA level of HER2 (p>0.05).

CONCLUSIONS

Influence of HER2 gene expression is a new feature and mechanism of action observed only in dual action DOX-MTX-NPs treated groups. Down-regulation of HER2 mRNA as a promising marker and prognosticator of OSCC adds to the cytotoxic benefits of DOX in its new formulation. Both oral and IV application of this nanodrug could be used, with no preferences in term of their safety or toxicity. As HER2 is expressed abundantly by a wide spectrum of tumors, i DOX-MTX NPs may be useful for a wide-spectrum of lesions. However, molecular mechanisms underlying HER2 down regulation induced by DOX-MTX NPs remain to be addressed.

DOX-MTX-NPs augment p53 mRNA expression in OSCC model in rat: effects of IV and oral routes

BACKGROUND

Oral squamous cell carcinoma (OSCC) is the sixth most common malignancy worldwide. Cancer development and progression require inactivation of tumor suppressor genes and activation of proto-oncogenes. The well recognized mechanism of action demonstrated for chemotherapeutic agents is induction of apoptosis via reactivation of p53. In this context, we evaluate the efficacy of IV and oral routes of our novel PH and temperature sensitive doxorubicin-methotrexate-loaded nanoparticles (DOX-MTX NP) in affecting p53 profile in an OSCC rat model.

METHODS

In this study, 120 male rats were divided into 8 groups of 15 animals each. The new formulated DOX-MTX NP and free doxorubicin were IV and orally given to rats with 4-nitroquinoline-1- oxide induced OSCC.

RESULTS

RESULTS showed that both DOX and DOX-MTX-NP caused significant increase in mRNA levels of P53 compared to the untreated group (p<0.000). With both DOX and DOX-MTX NP, the IV mode was more effective than the oral (gavage) route (p<0.000). Surprisingly, in oral mode, p53 mRNA was not affected in DOX treated groups (p>0.05), Nonetheless, both IV and oral administration of MTX-DOX NP showed superior activity (~3 fold) over free DOX in reactivation of p53 in OSCC (p<0.000). The effectiveness of oral route in group treated with nanodrug accounts for the enhanced bioavailability of nanoparticulated DOX- MTX compared to free DOX. Moreover, in treated groups, tumor stage was markedly related to the amount of p53 mRNA (p<0.05).

CONCLUSION

Both oral and IV application of our novel nanodrug possesses superior activity over free DOX-in up-regulation of p53 in a OSCC model and this increase in p53 level associated with less aggressive tumors in our study. Although, impressive results obtained with IV form of nanodrug (-21 fold increase in p53 mRNA level) but both forms of nanodrug are effective in OSCC, with less toxicity normal cells.

Effect of methotrexate on cerebellar development in infant rats

Six-day-old rats were treated intraperitoneal injections with methotrexate 1 mg/kg, and the cerebellum was examined. Both the length and width of the vermis decreased in the methotrexate-treated group instead of the control from 4 day after treatment (DAT) onward. A significant reduction in the width of the external granular layer was detected on 2 and 3 DAT in the methotrexate group. By 4 DAT, the width of the external granular layer of the methotrexate group was indistinguishable from the control, and by 8 DAT, it was greater than that of the control. The molecular layer of methotrexate group on 8 and 15 DAT was thinner than that of the control. On 1 DAT, in the methotrexate group, there were many TUNEL and cleaved caspase-3-positive granular cells throughout the external granular layer, and they decreased time-dependently. On 1 DAT, in the methotrexate group, phospho-histone H3-positive cells in the external granular layer were fewer than in the control and tended to increase on 2–4 DAT. The p21-positive-rate of the external granule cells in the MTX group was higher than in the control on 1–4 DAT. These results suggested that methotrexate exposure on postnatal day 6 induces a delay, slowing in the migration of external granular cells to the inner granular layer, attributed to decrease or inhibition in the production of external granular cells that had arisen from apoptosis and the decrease in cell proliferative activity, resulting in cerebellar hypoplasia.

Identification of novel small compounds that restore E-cadherin expression and inhibit tumor cell motility and invasiveness

Tumor dissemination and invasive behavior are associated with a majority of cancer-related mortality cases. Loss of E-cadherin, which is caused by several tumor-promoting factors, is associated with metastasis and poor prognosis in many neoplasms. In this study, we aimed to identify small molecule compounds that restore the expression of E-cadherin, because these molecules are most likely to suppress tumor malignancy by restoring E-cadherin function and/or by inhibiting signals that suppress E-cadherin expression. Here, we developed a fluorescence screen system based on E-cadherin expression. A pilot drug library screen revealed that methotrexate (MTX) strongly induces E-cadherin expression in a colorectal cancer cell line, SW620. From the screen for 9600 compounds, we identified 9 hit compounds, which restored the expression of E-cadherin in SW620 and/or a melanoma cell line, SK-MEL-28. We confirmed that MTX and the other identified compounds transcriptionally promote E-cadherin expression. Among these, 2 compounds suppressed migration/invasion capacity in colorectal cancer cells and 3 in melanoma cells. A compound reduced SW620 migration and invasion with subtle effects on cell viability in SW620, SK-MEL-28, and a non-tumor cell line, HaCaT, with decrease in AKT and ERK1/2 protein levels. One of the other compounds reduced SK-MEL-28 cell migration and invasion and affected the viability only of SW620 and SK-MEL-28 cells but not HaCaT cells. These results suggest that these compounds would be attractive lead molecules as anti-metastasis agents.

The effect of systemic chemotherapy on neurogenesis, plasticity and memory

Chemotherapy has been enormously successful in treating many forms of cancer and improving patient survival rates. With the increasing numbers of survivors, a number of cognitive side effects have become apparent. These have been called "chemobrain" or "chemofog" among patient groups, who describe the symptoms as a decline in memory, concentration and executive functions. Changes which, although subtle, can cause significant distress among patients and prevent a return to the quality of life experienced before treatment. This cognitive side effect of chemotherapy was not anticipated as it had been assumed that chemotherapy agents, administered systematically, could not cross the blood-brain barrier and that the brain was therefore protected from their action. It is now realised that low concentrations of many chemotherapy agents cross the blood-brain barrier and even those that are completely prevented from doing so, can induce the production of inflammatory cytokines in peripheral tissues which in turn can cross the blood-brain barrier and impact on the brain. A large number of patient studies have shown that cognitive decline is found in a proportion of patients treated with a variety of chemotherapy agents for different types of cancer. The deficits experienced by these patients can last for up to several years and have a deleterious effect on educational attainment and ability to return to work. Imaging studies of patients after systemic chemotherapy show that this treatment produces structural and functional changes in the brain some of which seem to persist even when the cognitive deficits have ceased. This suggests that, with time, brain plasticity may be able to compensate for the deleterious effects of chemotherapy treatment. A number of mechanisms have been suggested for the changes in brain structure and function found after chemotherapy. These include both central and peripheral inflammatory changes, demyelination of white matter tracts, a reduction in stem cell proliferation in both the hippocampal neurogenic region and by oligodendrocyte precursors as well as changes in hormonal or growth factor levels. A number of possible treatments have been suggested which range from pharmacological interventions to cognitive behavioural therapies. Some of these have only been tested in animal models while others have produced varying degrees of improvement in patient populations. Currently, there is no recognised treatment and a greater understanding of the causes of the cognitive decline experienced after chemotherapy will be key to finding ways of preventing or treating the effects of chemobrain.

Role of microRNA-138 as a potential tumor suppressor in head and neck squamous cell carcinoma

Head and neck squamous cell carcinoma (HNSCC) is an aggressive life-threatening disease associated with high mortality rates. While efforts have been made to explore the molecular mechanisms that contribute to the initiation and progression of HNSCC, most studies focus on protein-coding genes. Understanding of the genomic aberrations associated with noncoding genes (such as microRNAs) and their effects on HNSCC is still relatively limited. Recent evidence suggests that deregulation of microRNA genes (such as downregulation of miR-138) plays an important role in HNSCC. While deregulation of miR-138 has been frequently observed in HNSCC and other cancer types, the precise roles of miR-138 in tumorigenesis remain elusive. Recent bioinformatics analyses and functional studies using in vitro and in vivo systems have identified a number of functional targets for miR-138. These include genes that participate in essential biological processes that are highly relevant to the initiation and progression of HNSCC, including cell migration, epithelial to mesenchymal transition, cell cycle progression, DNA damage response and repair, senescence, and differentiation. However, the biological systems, study design, and data interpretation from these studies are highly variable, which hinder our understanding of the role of miR-138 in tumorigenesis at molecular level. In this review, we will first introduce the significance of microRNA deregulation in HNSCC. We will then provide a comprehensive review and integrative analysis of the existing studies on miR-138, and aim to define its molecular mechanisms that contribute to the initiation and progression of HNSCC.

Enhancer of zeste homolog 2 is overexpressed and contributes to epigenetic inactivation of p21 and phosphatase and tensin homolog in B-cell acute lymphoblastic leukemia

Enhancer of zeste homolog 2 (EZH2) is crucially involved in epigenetic silencing by acting as a histone methyltransferase. Although EZH2 is overexpressed in many solid cancers, the role of EZH2 in B-cell acute lymphoblastic leukemia (B-ALL) remains largely unexplored. In a microarray experiment, we found that EZH2 was significantly upregulated in Nalm-6 cells and this was associated with the silencing of tumor suppressor genes p21, p53 and phosphatase and tensin homolog (PTEN). The abnormal expression of these genes was further confirmed by quantitative realtime polymerase chain reaction and Western blot analysis on Nalm-6 cells. Chromatin immunoprecipitation assay showed that EZH2 and H3K27me3 were both enriched in the promoter region of PTEN and p21 in Nalm-6 cells but not in normal B cells. Functional analysis showed that siRNA-mediated EZH2 knockdown led to decreased proliferation and increased apoptosis of Nalm-6 cells, accompanied by the reactivation of PTEN and p21 expression. Furthermore, we found that EZH2 inhibitor deazaneplanocin A promoted vincristine sulfate-induced apoptosis of Nalm-6 cells. Taken together, our data suggest that EZH2 is overexpressed in B-ALL and promotes the progression of B-ALL by directly mediating the inactivation of tumor suppressor genes p21 and PTEN, and could serve as a potential epigenetic target for B-ALL therapy.

Activation of p21-Dependent G1/G2 Arrest in the Absence of DNA Damage as an Antiapoptotic Response to Metabolic Stress

The folate enzyme, FDH (10-formyltetrahydrofolate dehydrogenase, ALDH1L1), a metabolic regulator of proliferation, activates p53-dependent G1 arrest and apoptosis in A549 cells. In the present study, we have demonstrated that FDH-induced apoptosis is abrogated upon siRNA knockdown of the p53 downstream target PUMA. Conversely, siRNA knockdown of p21 eliminated FDH-dependent G1 arrest and resulted in an early apoptosis onset. The acceleration of FDH-dependent apoptosis was even more profound in another cell line, HCT116, in which the p21 gene was silenced through homologous recombination (p21(-/-) cells). In contrast to A549 cells, FDH caused G2 instead of G1 arrest in HCT116 p21(+/+) cells; such an arrest was not seen in p21-deficient (HCT116 p21(-/-)) cells. In agreement with the cell cycle regulatory function of p21, its strong accumulation in nuclei was seen upon FDH expression. Interestingly, our study did not reveal DNA damage upon FDH elevation in either cell line, as judged by comet assay and the evaluation of histone H2AX phosphorylation. In both A549 and HCT116 cell lines, FDH induced a strong decrease in the intracellular ATP pool (2-fold and 30-fold, respectively), an indication of a decrease in de novo purine biosynthesis as we previously reported. The underlying mechanism for the drop in ATP was the strong decrease in intracellular 10-formyltetrahydrofolate, a substrate in two reactions of the de novo purine pathway. Overall, we have demonstrated that p21 can activate G1 or G2 arrest in the absence of DNA damage as a response to metabolite deprivation. In the case of FDH-related metabolic alterations, this response delays apoptosis but is not sufficient to prevent cell death.

MicroRNA-138 suppresses epithelial-mesenchymal transition in squamous cell carcinoma cell lines

Down-regulation of miR-138 (microRNA-138) has been frequently observed in various cancers, including HNSCC (head and neck squamous cell carcinoma). Our previous studies suggest that down-regulation of miR-138 is associated with mesenchymal-like cell morphology and enhanced cell migration and invasion. In the present study, we demonstrated that these miR-138-induced changes were accompanied by marked reduction in E-cad (E-cadherin) expression and enhanced Vim (vimentin) expression, characteristics of EMT (epithelial-mesenchymal transition). On the basis of a combined experimental and bioinformatics analysis, we identified a number of miR-138 target genes that are associated with EMT, including VIM, ZEB2 (zinc finger E-box-binding homeobox 2) and EZH2 (enhancer of zeste homologue 2). Direct targeting of miR-138 to specific sequences located in the mRNAs of the VIM, ZEB2 and EZH2 genes was confirmed using luciferase reporter gene assays. Our functional analyses (knock-in and knock-down) demonstrated that miR-138 regulates the EMT via three distinct pathways: (i) direct targeting of VIM mRNA and controlling the expression of VIM at a post-transcriptional level, (ii) targeting the transcriptional repressors (ZEB2) which in turn regulating the transcription activity of the E-cad gene, and (iii) targeting the epigenetic regulator EZH2 which in turn modulates its gene silencing effects on the downstream genes including E-cad. These results, together with our previously observed miR-138 effects on cell migration and invasion through targeting RhoC (Rho-related GTP-binding protein C) and ROCK2 (Rho-associated, coiled-coil-containing protein kinase 2) concurrently, suggest that miR-138 is a multi-functional molecular regulator and plays major roles in EMT and in HNSCC progression.

Chemotherapy-induced cognitive impairment is associated with decreases in cell proliferation and histone modifications

Background

In this study, we examined the effects of cyclophosphamide, methothrexate, and 5-Fluorouracil (CMF) drug combination on various aspects of learning and memory. We also examined the effects of CMF on cell proliferation and chromatin remodeling as possible underlying mechanisms to explain chemotherapy-associated cognitive dysfunction. Twenty-four adult female Wistar rats were included in the study and had minimitter implantation for continuous activity monitoring two weeks before the chemotherapy regimen was started. Once baseline activity data were collected, rats were randomly assigned to receive either CMF or saline injections given intraperitoneally. Treatments were given once a week for a total of 4 weeks. Two weeks after the last injection, rats were tested in the water maze for spatial learning and memory ability as well as discrimination learning. Bromodeoxyuridine (BrdU) injection was given at 100 mg/Kg intraperitoneally 4 hours prior to euthanasia to determine hippocampal cell proliferation while histone acetylation and histone deacetylase activity was measured to determine CMF effects on chromatin remodeling.

Results

Our data showed learning and memory impairment following CMF administration independent of the drug effects on physical activity. In addition, CMF-treated rats showed decreased hippocampal cell proliferation, associated with increased histone acetylation and decreased histone deacetylase activity.

Conclusions

These results suggest the negative consequences of chemotherapy on brain function and that anti-cancer drugs can adversely affect the self-renewal potential of neural progenitor cells and also chromatin remodeling in the hippocampus. The significance of our findings lie on the possible usefulness of animal models in addressing the clinical phenomenon of 'chemobrain.'

Cell death signaling and anticancer therapy

For a long time, it was commonly believed that efficient anticancer regimens would either trigger the apoptotic demise of tumor cells or induce a permanent arrest in the G₁ phase of the cell cycle, i.e., senescence. The recent discovery that necrosis can occur in a regulated fashion and the increasingly more precise characterization of the underlying molecular mechanisms have raised great interest, as non-apoptotic pathways might be instrumental to circumvent the resistance of cancer cells to conventional, pro-apoptotic therapeutic regimens. Moreover, it has been shown that some anticancer regimens engage lethal signaling cascades that can ignite multiple oncosuppressive mechanisms, including apoptosis, necrosis, and senescence. Among these signaling pathways is mitotic catastrophe, whose role as a bona fide cell death mechanism has recently been reconsidered. Thus, anticancer regimens get ever more sophisticated, and often distinct strategies are combined to maximize efficacy and minimize side effects. In this review, we will discuss the importance of apoptosis, necrosis, and mitotic catastrophe in the response of tumor cells to the most common clinically employed and experimental anticancer agents.