EGFP fluorescence as an indicator of cancer cells response to methotrexate

Antigen presentation capability and AP-1 activation accompany methotrexate-induced colon cancer cell senescence in the context of aberrant β-catenin signaling

Reversible cellular senescence was demonstrated previously to constitute colon cancer cell response to methotrexate. The current study presents a comparison of two senescent states of colon cancer cells, arrested and reversing, resulting from respectively, 120 h exposure to the drug, and 48 h exposure followed by 96 h regrowth in drug-free media. The upregulation of immunoproteasome subunit-coding genes and the increase in human leukocyte antigen HLA-A/B/C membrane level indicated MHC-I-restricted antigen presentation as common to both senescent states. Nuclear factor NF-κB p65 level decreased and activating protein AP-1: c-Jun, Fra2 and JunB nuclear levels increased in both senescent cell populations. Notably, the increase in AP-1- dependent transcription occurred after 48 h exposure to methotrexate. β-catenin nuclear level increased after 48 h exposure to the drug and remained as such only in senescence-arrested cells. β-catenin level was found uncoupled from the protein phosphorylation status indicating the deregulation of β-catenin signaling in colon cancer cells employed in the study. These findings carry implications for both, a general mechanism of senescence establishment and putative advantages for colon cancer treatment.

Synthesis, reactivity and biological activity of N(4)-boronated derivatives of 2'-deoxycytidine

By seeking new stable boron-containing nucleoside derivatives, potential BNCT boron delivery agents, a novel synthetic approach was tested, aimed at a boron attachment via a single bond to an aliphatic carbon of sp(3) hybridization. The latter allowed successful modification of deoxycytidine in the reaction with 2-(iodomethyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane of the deoxynucleoside amino group. For new compounds, detailed NMR, LDI HRMS (Laser Desorption/Ionization High-Resolution Mass Spectrometry) analyses along with in vivo phosphorylation studies, toxicity assays and DFT modelling are presented.

Drug loading and release on tumor cells using silk fibroin-albumin nanoparticles as carriers

Polymeric and biodegradable nanoparticles are frequently used in drug delivery systems. In this study silk fibroin-albumin blended nanoparticles were prepared using the desolvation method without any surfactant. These nanoparticles are easily internalized by the cells, reside within perinuclear spaces and act as carriers for delivery of the model drug methotrexate. Methotrexate loaded nanoparticles have better encapsulation efficiency, drug loading ability and less toxicity. The in vitro release behavior of methotrexate from the nanoparticles suggests that about 85% of the drug gets released after 12 days. The encapsulation and loading of a drug would depend on factors such as size, charge and hydrophobicity, which affect drug release. MTT assay and conjugation of particles with FITC demonstrate that the silk fibroin-albumin nanoparticles do not affect the viability and biocompatibility of cells. This blended nanoparticle, therefore, could be a promising nanocarrier for the delivery of drugs and other bioactive molecules.

Functional gene expression profile underlying methotrexate-induced senescence in human colon cancer cells

Cellular functions accompanying establishment of premature senescence in methotrexate-treated human colon cancer C85 cells are deciphered in the present study from validated competitive expression microarray data, analyzed with the use of Ingenuity Pathways Analysis (IPA) software. The nitrosative/oxidative stress, inferred from upregulated expression of inducible nitric oxide synthase (iNOS) and mitochondrial dysfunction-associated genes, including monoamine oxidases MAOA and MAOB, β-amyloid precursor protein (APP) and presenilin 1 (PSEN1), is identified as the main determinant of signaling pathways operating during senescence establishment. Activation of p53-signaling pathway is found associated with both apoptotic and autophagic components contributing to this process. Activation of nuclear factor κB (NF-κB), resulting from interferon γ (IFNγ), integrin, interleukin 1β (IL-1β), IL-4, IL-13, IL-22, Toll-like receptors (TLRs) 1, 2 and 3, growth factors and tumor necrosis factor (TNF) superfamily members signaling, is found to underpin inflammatory properties of senescent C85 cells. Upregulation of p21-activated kinases (PAK2 and PAK6), several Rho molecules and myosin regulatory light chains MYL12A and MYL12B, indicates acquisition of motility by those cells. Mitogen-activated protein kinase p38 MAPK β, extracellular signal-regulated kinases ERK2 and ERK5, protein kinase B AKT1, as well as calcium, are identified as factors coordinating signaling pathways in senescent C85 cells.

Methotrexate-induced senescence in human adenocarcinoma cells is accompanied by induction of p21(waf1/cip1) expression and lack of polyploidy

Human colorectal adenocarcinoma C85 cells, treated with high dose methotrexate (1 microM; IC(50)=51 nM), undergo accelerated senescence, as the cells (i) are growth arrested at the G(1) and S phases of the cell cycle, (ii) are SA-beta-galactosidase-positive, (iii) show induced expression of p21(waf1/cip1) and decreased expression of p16(INK4a), and (iv) show DNA synthesis continued at the reduced level. The fraction of C85 cells with DNA content higher than 4N is maintained at the same level (14%) in cells untreated, as well as regrown after the treatment. Multinucleation is found as the main karyotypic abnormality.