Methotrexate differentially affects growth of suspension and adherent cells

The metabolite 5-methyl-1,3-benzenediol and its derivative methyl-2,4-dihydroxy-6-methylbenzoate from the lichen Parmotrema tinctorum with potent apoptotic and anti-angiogenesis effects

Nature has been a rich resource of novel anticancer agents, one such source being lichens, which represent the symbiosis between algae and fungi with diverse range of secondary metabolites having therapeutic significance. With respect to this, the present study evaluates the in vitro apoptogenic profile of secondary metabolites from the lichen Parmotrema tinctorum towards cancer cell lines. Treatment with TLC-purified fraction 1 from P. tinctorum resulted in significant reduction in the cell viabilities of cancer cells with IC50 values ranging between 1.2 and 12.8 μg/ml. The potential anticancer effect of the bioactive fraction was further supported by Trypan blue cell viability, LDH and DNA fragmentation assays. At the cellular level, induction of apoptosis was confirmed through the activation of the caspase cascade and apoptotic cells accumulating in the Sub-G1 phase of cell cycle. Angiogenesis being one of the major characteristics needed for cancer growth, the ability of the lichen fraction to inhibit angiogenesis was checked through in ovo Yolk Sac Membrane (YSM) assay and was found to be significant. The study also verified the non-toxic nature of the bioactive fraction towards normal human peripheral lymphocytes. HPLC analysis and GC-MS characterisation of the bioactive fraction indicated the presence of 5-methyl-1,3-benzenediol and its derivative methyl-2,4-dihydroxy-6-methylbenzoate.

Suspension State Promotes Drug Resistance of Breast Tumor Cells by Inducing ABCC3 Overexpression

Mechanical microenvironment plays a critical role in cancer drug resistance and this study supposed that suspension state might be involved in drug resistance of breast tumor cells. The viability of cell was detected by 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) assay. Cell cycle and apoptosis were detected by flow cytometry. Gene and protein were tested by RT-qPCR and Western blot, respectively. Drug resistance of MDA-MB-231 cells cultured for 72 h under suspension state was significantly increased. Suspension state was found to induce the overexpression of adenosine triphosphate-binding cassette subfamily C member 3 (ABCC3) in MDA-MB-231 cells. Silencing of ABCC3 significantly decreased drug resistance of suspension MDA-MB-231 cells. Moreover, suspension state was able to increase lamin A/C accumulation in MDA-MB-231 cells and lamin A/C regulated the expression of ABCC3. Moreover, lamin A/C knockdown also decreased drug resistance of suspension MDA-MB-231 cells, but the effect on drug resistance was less than that of ABCC3 knockdown. Suspension state plays a vital role in promoting drug resistance of MDA-MB-231 cells by inducing ABCC3 overexpression, and lamin A/C accumulation is associated with this process.

Disparate Response to Methotrexate in Stem Versus Non-Stem Cells

Methotrexate (MTX) is a commonly used chemotherapeutic agent that kills cancer cells by binding dihydrofolate reductase (DHFR) as a competitive inhibitor. Due to its non-selectivity, MTX also impairs normal (non-cancerous) cell function and causes long-term damage to healthy tissue. These consequences have been investigated extensively in bone-derived cells due to their sensitivity to the drug. While DHFR likely plays a role in normal cell response to MTX, research in this area is limited. Moreover, how MTX sensitivity differs among cell types responsible for maintaining connective tissues is unknown. The goal of this study was to investigate the role of DHFR and subsequent nucleotide synthesis in normal cell response to MTX. We also sought to compare adverse effects of MTX among normal cell types to identify sensitive populations and resistant cell sources for regenerative procedures targeting patients undergoing chemotherapy. DHFR overexpression or exogenous amino acid + nucleoside delivery rescued normal cells from adverse MTX effects. Conversely, DHFR knockdown impaired MTX-treated adipose-derived stem cell (ASC) osteogenesis. Proliferation of ASCs and bone marrow stem cells was more resistant to MTX than that of terminally differentiated osteoblasts. However, stem cells became susceptible to the drug after beginning differentiation. These results suggest that the ability of stem cells to survive and to maintain their surrounding tissues likely depends on whether they are in a "stem" state when exposed to MTX. Therapeutic strategies that delay the differentiation of stem cells until clearance of the drug may produce more favorable outcomes in the long-term health of treated tissues.

Comparative Phytochemical Analysis of Essential Oils from Different Biological Parts of Artemisia herba alba and Their Cytotoxic Effect on Cancer Cells

PURPOSE

Carrying out the chemical composition and antiproliferative effects against cancer cells from different biological parts of Artemisia herba alba.

METHODS

Essential oils were studied by gas chromatography coupled to mass spectrometry (GC-MS) and their antitumoral activity was tested against P815 mastocytoma and BSR kidney carcinoma cell lines; also, in order to evaluate the effect on normal human cells, oils were tested against peripheral blood mononuclear cells PBMCs.

RESULTS

Essential oils from leaves and aerial parts (mixture of capitulum and leaves) were mainly composed by oxygenated sesquiterpenes 39.89% and 46.15% respectively; capitulum oil contained essentially monoterpenes (22.86%) and monocyclic monoterpenes (21.48%); esters constituted the major fraction (62.8%) of stem oil. Essential oils of different biological parts studied demonstrated a differential antiproliferative activity against P815 and BSR cancer cells; P815 cells are the most sensitive to the cytotoxic effect. Leaves and capitulum essential oils are more active than aerial parts. Interestingly, no cytotoxic effect of these essential oils was observed on peripheral blood mononuclear cells.

CONCLUSION

Our results showed that the chemical composition variability of essential oils depends on the nature of botanical parts of Artemisia herba alba. Furthermore, we have demonstrated that the differential cytotoxic effect depends not only on the essential oils concentration, but also on the target cells and the botanical parts of essential oils used.

Methotrexate treatment causes early onset of disease in a mouse model of Ross River virus-induced inflammatory disease through increased monocyte production

Part of the Togaviridae family, alphaviruses, including chikungunya virus (CHIKV), Sindbis virus (SINV) and Ross River virus (RRV), are able to cause significant inflammatory pathologies ranging from arthritis to encephalitis. Following symptomatic infection with arthritis-associated alphaviruses, patients often experience severe joint pain, affecting distal and small joints, which can last six months or longer. Recently, methotrexate (MTX), a disease modifying anti-rheumatic drug (DMARD), was used to treat patients experiencing chronic rheumatic symptoms following infection with CHIKV. Here, the effect of MTX on Ross River virus disease (RRVD) in mice was examined to better understand its therapeutic potential for alphaviral-induced musculoskeletal disease and to further our knowledge of the development of alphaviral pathologies. Using a mouse model, we analyzed the effect of MTX on RRVD. RRV disease pathogenesis in response to MTX treatment was determined by measuring levels of proinflammatory factors, cellular infiltrates, viral titer and histological analysis of infected tissues. RRV-infected mice receiving MTX treatment rapidly developed musculoskeletal disease, which correlated with a significant influx of inflammatory cell infiltrates into the skeletal muscle tissue. Although no difference was observed in the level of proinflammatory cytokines and chemokines, the viral load increased at early time points post infection in the serum and quadriceps of MTX treated mice, possibly contributing to disease pathogenesis. Results suggest that MTX treatment of acute RRVD in mice provides no therapeutic benefit and underline the importance of inflammatory monocytes in alphaviral induced arthritides.

Protective effects of erythropoietin and N-acetylcysteine on methotrexate-induced lung injury in rats

OBJECTIVE

Methotrexate (MTX) is known to have deleterious side effects on lung tissue. We aimed to investigate the effects of erythropoietin (EPO) and N-acetyl-cysteine (NAC) on MTX-induced lung injury in rats.

STUDY DESIGN

Animal experiment.

MATERIAL AND METHODS

Twenty-six female Sprague-Dawley rats were divided into 4 groups. Sham group, 0.3 mL saline; MTX group, 5 mg/kg MTX; EPO group, 5mg/kg MTX and 2000 IU/kg EPO; NAC group, 5 mg/kg MTX and 200 mg/kg NAC were administered once daily for 4 consecutive days. Malondialdehyde (MDA), superoxide dismutase (SOD), catalase (CAT) and inflammation and congestion scores in lung tissues were evaluated.

RESULTS

In MTX group MDA were significantly higher, CAT and SOD were significantly lower than in sham, EPO and NAC groups (p<0.005). In EPO group MDA, CAT, and SOD were higher, but not significant than those in group NAC (p>0.005). In group MTX both scores were significantly higher than in sham (p<0.005). The congestion score of group MTX was significantly higher than those of group EPO and NAC (p<0.005).

CONCLUSION

EPO and NAC have significant preventive effects on MTX-induced lung injury in rats. Decreased antioxidant capacity and increased MDA level may cause the oxidative damage in MTX group. Also, higher antioxidant capacity and lower MDA level may be a response to oxidative stress in EPO and NAC groups.

Acute treatment with methotrexate induces hippocampal dysfunction in a mouse model of breast cancer

Methotrexate (MTX) is a well-known cytostatic agent used in adjuvant chemotherapy for breast cancer, that has neurological side effects, including depression and cognitive impairment. We investigated the neurotoxic effects of MTX on the hippocampus and hippocampus-dependent behaviors in breast cancer cell line (FM3A)-inoculated tumor-bearing mice. In addition, we evaluated the changes in inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) expression in the hippocampus of tumor-bearing mice after treatment with MTX. Depressive-like behavior test (tail-suspension test, TST) and learning and memory tasks (passive avoidance) were administered 24h after MTX (40 mg/kg, i.p.) injection. MTX-treated tumor-bearing mice showed significant depressive-like behaviors and cognitive impairment. Treatment with MTX significantly decreased the number of doublecortin (a marker for immature progenitor neurons)-positive cells in the hippocampal dentate gyrus of tumor-free and tumor-bearing mice. Moreover, treatment with MTX significantly upregulated proinflammatory enzymes, including iNOS and COX-2, in tumor-bearing mice. These findings indicate that the acute neurotoxic effect of MTX leads to hippocampal dysfunction including depressive-like behaviors and memory deficits, which may be related to an inhibition of neurogenesis and an increase of the inflammatory response in the hippocampus of a mouse model of breast cancer.

Differential influences of bucillamine and methotrexate on the generation of fibroblast-like cells from bone marrow CD34+ cells of rheumatoid arthritis patients

We have recently demonstrated that bone marrow CD34+ cells from rheumatoid arthritis (RA) patients displayed abnormal capacities to respond to TNF-alpha and to differentiate into fibroblast-like cells producing MMP-1 (type B synoviocyte -like cells). The current study examined the effects of representative potent disease-modifying antirheumatic drugs, including bucillamine (BUC) and methotrexate (MTX) on the in vitro generation of fibroblast-like cells from RA bone marrow CD34+ cells. CD34+ cells purified from bone marrow specimens of 8 patients with active RA were cultured in the presence or absence of pharmacologically attainable concentrations of intramolecular disulfide form of bucillamine (BUC-ID, 3 microM), a major metabolite of BUC or MTX (20 nM). After incubation for 28 days, the generation of fibroblast-like cells was assessed under phase-contrast light microscopy and the concentrations of MMP-1 and VEGF in the culture supernatants were measured by ELISA. BUC-ID, but not MTX, significantly suppressed the generation of fibroblast-like cells from RA bone marrow CD34+ cells stimulated with SCF, GM-CSF and TNF-alpha (p=0.024 as determined by Wilcoxon signed rank test). Accordingly, BUC-ID, but not MTX, significantly suppressed the production of MMP-1 (p=0.017) and VEGF (p=0.017) by RA bone marrow CD34+ cells, without inhibition of beta2-microglobulin production. These results demonstrate that BUC-ID, but not MTX, is a potent inhibitor of differentiation of fibroblast-like cells from RA bone marrow CD34+ cells. Since MTX, but not BUC, has been previously shown to influence on type A synoviocytes, the data provide rationale of combination of BUC and MTX in the treatment of RA.

Effects of antisense RNA targeting of ODC and AdoMetDC on the synthesis of polyamine synthesis and cell growth in prostate cancer cells using a prostatic androgen-dependent promoter in adenovirus

PURPOSE

This study was designed to investigate the use of a prostatic androgen-dependent promoter to mediate antisense targeting of ornithine decarboxylase (ODC) and S-adenosylmethionine decarboxylase (AdoMetDC) and its effects on the synthesis of polyamine. We also examined the potential of this construct for prostate cancer therapy.

METHODS

pADxsi-PSES-AdoMetDC-ODC-PolyA AV was constructed and used to infect various cancer cell lines, including LNCaP, HT-29, H1299, HepG2. The effects of pADxsi-PSES-AdoMetDC-ODC-PolyA AV on the expression of ODC and AdoMetDC, in addition to the cell cycle, apoptosis and p21 levels, were analyzed through Western blotting and cytometry. A Matrigel invasion assay was used to analyze the effects of the recombinant virus on tumor cell invasion. The effect on polyamine content was also determined, and the relationship between inhibition of cellular ODC and AdoMetDC and decreases in polyamine were also investigated using a polyamine recovery assay.

RESULTS

Treatment with pADxsi-PSES-AdoMetDC-ODC-PolyA at an MOI of 90 significantly inhibited the proliferation of LNCaP cells, which could not be recovered through the addition of exogenous putrescine. The expression of ODC and AdoMetDC was also reduced, as was the polyamine content. The G1 phase of LNCaP cells was delayed, but no increase in apoptosis was detected. The down-regulation of ODC and AdoMetDC led to increased p21 expression.

CONCLUSIONS

The pADxsi-PSES-AdoMetDC-ODC-PolyA AV specifically inhibited the expression of ODC and AdoMetDC and the synthesis of polyamine, while it induced p21 expression, resulting in cell growth arrest in the G1 phase in prostate cancer cells but not in other cells.

Inhibition of c-Myc down-regulation by sustained extracellular signal-regulated kinase activation prevents the antimetabolite methotrexate- and gemcitabine-induced differentiation in non-small-cell lung cancer cells

Non-small-cell lung cancer (NSCLC) is characterized by severe resistance to chemotherapy. Here, we demonstrate that A549 adenocarcinoma cells permanently differentiate with the antimetabolites methotrexate (MTX) and gemcitabine (GE) when blocking the resistance mechanism that normally counteracts this process. MTX (1-10 microM) and GE (1 microM) induced growth arrest accompanied by sustained extracellular signal-regulated kinase (ERK1/2) phosphorylation and moderate reduction of c-Myc levels after 96 h, whereas only a low percentage of the cells differentiated. Combination with the mitogen-activated protein kinase kinase (MEK) inhibitor 1,4-diamino-2,3-dicyano-1,4-bis-(methylthio)butadiene (U0126) reduced MTX- or GE-induced ERK1/2 over-phosphorylation, nearly abolished c-Myc expression, and provoked radical morphological changes in all cells. Besides the appearance of multilamellar bodies and intracellular cytokeratin reorganization, modulation of molecular markers occurred in a manner consistent with differentiation (gelsolin, +300%; surfactant protein A and C, -70%). Similar to U0126, c-Myc inactivation with specific small interfering RNA initiated differentiation only in the presence of MTX, demonstrating that inhibition of the mitogen-activated protein kinase/ERK pathway alone or down-regulation of c-Myc is not sufficient to induce this process. It is noteworthy that withdrawal of antitumoral drugs and U0126 neither reversed differentiation nor reactivated proliferation. Our results reveal that maintenance of a certain threshold of c-Myc expression through sustained ERK1/2 activation represents a molecular mechanism that confers resistance to antimetabolite-induced differentiation in A549 cells, and provide a novel molecular basis for therapeutic strategies based on irreversible differentiation of cancer cells using conventional chemotherapeutic antimetabolites in combination with inhibitors of the MEK/ERK pathway or c-Myc.

Role of an invariant lysine residue in folate binding on Escherichia coli thymidylate synthase: calorimetric and crystallographic analysis of the K48Q mutant

Thymidylate synthase (TS) catalyzes the reductive methylation of deoxyuridine monophosphate (dUMP) using methylene tetrahydrofolate (CH(2)THF) as cofactor, the glutamate tail of which forms a water-mediated hydrogen bond with an invariant lysine residue of this enzyme. To understand the role of this interaction, we studied the K48Q mutant of Escherichia coli TS using structural and biophysical methods. The k(cat) of the K48Q mutant was 430-fold lower than wild-type TS in activity, while the K(m) for the (R)-stereoisomer of CH(2)THF was 300 microM, about 30-fold larger than K(m) from the wild-type TS. Affinity constants were determined using isothermal titration calorimetry, which showed that binding was reduced by one order of magnitude for folate-like TS inhibitors, such as propargyl-dideazafolate (PDDF) or compounds that distort the TS active site like BW1843U89 (U89). The crystal structure of the K48Q-dUMP complex revealed that dUMP binding is not impaired in the mutant, and that U89 in a ternary complex of K48Q-nucleotide-U89 was bound in the active site with subtle differences relative to comparable wild-type complexes. PDDF failed to form ternary complexes with K48Q and dUMP. Thermodynamic data correlated with the structural determinations, since PDDF binding was dominated by enthalpic effects while U89 had an important entropic component. In conclusion, K48 is critical for catalysis since it leads to a productive CH(2)THF binding, while mutation at this residue does not affect much the binding of inhibitors that do not make contact with this group.

Methotrexate induced differentiation in colon cancer cells is primarily due to purine deprivation

The folate antagonist methotrexate (MTX) inhibits synthesis of tetrahydrofolate (THF), pyrimidines and purines, and induces differentiation in several cell types. At 1 microM, MTX reduced proliferation and induced differentiation in HT29 colon cancer cells; the latter effect was augmented (P < 0.001) by thymidine (100 microM) but was reversed (P < 0.001) by the purines, hypoxanthine (Hx; 100 microM) and adenosine (100 microM). In contrast 5-fluoro-uracil (5-FU), a specific thymidylate synthase (TS) inhibitor, had no effect on differentiation, suggesting that MTX-induced differentiation is not due to a reduction in thymidine but to the inhibition of purine biosynthesis. Inhibition of cyclic AMP (cAMP) by RpcAMP (25 microM) further enhanced (P < 0.001) MTX induced differentiation, whereas the cAMP activator forskolin (10 microM) reversed (P < 0.001) MTX induced differentiation. These observations implicate a central role of adenosine and cAMP in MTX induced differentiation. By combining Western blot analysis with liquid chromatography-mass spectrometry (LC-MS)and HPLC analyses we also reveal both the expression and activity of key enzymes (i.e. methionine synthase (MS), s-adenosylhomocysteinase, cystathionine beta-synthase and ornithine decarboxylase) regulating methyl cycle, transsulfuration and polyamine pathways in HT29 colon cancer cells. At 1 microM, MTX induced differentiation was associated with a marked reduction in the intracellular concentrations of adenosine and, consequently, S-adenosylmethionine (SAM), S-adenosylhomocysteine, polyamines and glutathione (GSH). Importantly, the marked reduction in methionine that accompanied MS inhibition following MTX treatment was non-limiting with respect to SAM synthesis. Collectively, these findings indicate that the effects of MTX on cellular differentiation and single carbon metabolism are primarily due to the intracellular depletion of purines.