CXCR2 Inhibition Combined with Sorafenib Improved Antitumor and Antiangiogenic Response in Preclinical Models of Ovarian Cancer

Antiangiogenic therapy is important for the treatment of gynecological cancer. However, the therapeutic benefit derived from these treatments is transient, predominantly due to the selective activation of compensatory proangiogenic pathways that lead to rapid development of resistance. We aimed to identify and target potential alternative signaling to anti-vascular endothelial growth factor (VEGF) therapy, with a view toward developing a combination of antiangiogenic agents to provide extended therapeutic benefits. We developed a preclinical in vivo phenotypic resistance model of ovarian cancer resistant to antiangiogenic therapy. We measured dynamic changes in secreted chemokines and angiogenic signaling in tumors and plasma in response to anti-VEGF treatment, as tumors advanced from the initial responsive phase to progressive disease. In tumors that progressed following sorafenib treatment, gene and protein expression levels of proangiogenic CXC chemokines and their receptors were significantly elevated, compared with responsive tumors. The chemokine (C-X-C motif) ligand 8 (CXCL8), also known as interleukin-8 (IL-8) increase was time-dependent and coincided with the dynamics of tumor progression. We used SB225002, a pharmacological inhibitor of chemokine (C-X-C motif) receptor 2 (CXCR2), to disrupt the CXC chemokine-mediated functions of ovarian cancer cells in in vitro assays of cell growth inhibition, spheroid formation, and cell migration. The combination of CXCR2 inhibitor with sorafenib led to a synergistic inhibition of cell growth in vitro, and further stabilized tumor progression following sorafenib in vivo. Our results suggest that CXCR2-mediated chemokines may represent an important compensatory pathway that promotes resistance to antiangiogenic therapy in ovarian cancer. Thus, simultaneous blockage of this proangiogenic cytokine pathway using CXCR2 inhibitors and the VEGF receptor (VEGFR) pathway could improve the outcomes of antiangiogenic therapy.     

Characterization and Propagation of Tumor Initiating Cells Derived from Colorectal Liver Metastases: Trials,Tribulations and a Cautionary Note

Tumor initiating cells (TIC) are increasingly being put forward as a potential target for intervention within colorectal cancer. Whilst characterisation and outgrowth of these cells has been extensively undertaken in primary colorectal cancers, few data are available describing characteristics within the metastatic setting. Tissue was obtained from patients undergoing surgical resection for colorectal liver metastases, and processed into single cell suspension for assessment. Tumor initiating cells from liver metastases were characterised using combinations of EPCAM, Aldehyde dehydrogenase activity, CD133 and CD26. CD133 expression was significantly lower in patients who had received chemotherapy, but this was accounted for by a decrease observed in the male patient cohort only. ALDH^high populations were rare (0.4 and 0.3% for EPCAM⁺/ALDH^high/CD133^- and EPCAM⁺/ALDH^high/CD133⁺ populations respectively) and below the limits of detection in 28% of samples. Spheroid outgrowth of metastatic tumor cells across all samples could not be readily achieved using standard spheroid-formation techniques, thus requiring further method validation to reliably propagate cells from the majority of tissues. Spheroid formation was not enhanced using additional growth factors or fibroblast co-culture, but once cells were passaged through NOD-SCID mice, spheroid formation was observed in 82% samples, accompanied by a significant increase in CD26. Order of spheroid forming ability was ALDH^high>CD133>CD26. Samples sorted by these markers each had the ability to reform ALDH^high, CD133 and CD26 positive populations to a similar extent, suggestive of a high degree of plasticity for each population. Ex vivo TIC models are increasingly being utilised to assess efficacy of therapeutic interventions. It is therefore essential that such investigations use well-characterised models that are able to sustain TIC populations across a large patient cohort in order that the inherent heterogeneity observed in cancer populations is maintained.     

Design, synthesis, and biological functionality of a dendrimer-based modular drug delivery platform

A modular dendrimer-based drug delivery platform was designed to improve upon existing limitations in single dendrimer systems. Using this modular strategy, a biologically active platform containing receptor mediated targeting and fluorescence imaging modules was synthesized by coupling a folic acid (FA) conjugated dendrimer with a fluorescein isothiocyanate (FITC) conjugated dendrimer. The two different dendrimer modules were coupled via the 1,3-dipolar cycloaddition reaction ("click" chemistry) between an alkyne moiety on the surface of the first dendrimer and an azide moiety on the second dendrimer. Two simplified model systems were also synthesized to develop appropriate "click" reaction conditions and aid in spectroscopic assignments. Conjugates were characterized by (1)H NMR spectroscopy and NOESY. The FA-FITC modular platform was evaluated in vitro with a human epithelial cancer cell line (KB) and found to specifically target the overexpressed folic acid receptor.     

Peptidoglycan biosynthesis machinery: a rich source of drug targets

The range of antibiotic therapy for the control of bacterial infections is becoming increasingly limited because of the rapid rise in multidrug resistance in clinical bacterial isolates. A few diseases, such as tuberculosis, which were once thought to be under control, have re-emerged as serious health threats. These problems have resulted in intensified research to look for new inhibitors for bacterial pathogens. Of late, the peptidoglycan (PG) layer, the most important component of the bacterial cell wall has been the subject of drug targeting because, first, it is essential for the survivability of eubacteria and secondly, it is absent in humans. The last decade has seen tremendous inputs in deciphering the 3-D structures of the PG biosynthetic enzymes. Many inhibitors against these enzymes have been developed using virtual and high throughput screening techniques. This review discusses the mechanistic and structural properties of the PG biosynthetic enzymes and inhibitors developed in the last decade.     

Evaluation of anti-depressant-like activity of linezolid, an oxazolidinone class derivative - an investigation using behavioral tests battery of depression

Linezolid, an oxazolidinone class derivative is a reversible and nonselective inhibitor of monoamine oxidase (MAO), predominantly for MAO-A type. MAO-A is a key enzyme regulating the catabolism of catecholamine neurotransmitters in the brain. It is well known that the catecholaminergic neuronal systems are associated with depression and inhibition of MAO-A level in the brain could be used to treat depression. Hence, the objective of this study was to evaluate the anti-depressant-like effect of linezolid, a MAO-A inhibitor in the animal models of depression. In the present study, linezolid (10 & 20 mg/kg, i.p.), exhibited anti-depressant-like effects in forced swim test (FST) and tail suspension test (TST) in mice without influencing the baseline locomotion. Moreover, linezolid (10 & 20 mg/kg, i.p.), potentiated the 5-hydroxytryptophan (5-HTP)-induced head twitch responses in mice and antagonized the reserpine-induced hypothermia in rats. In conclusion, the behavioral investigation revealed the anti-depressant-like effect of linezolid in rodent’s behavioral model.     

Recent developments and biological activities of thiazolidinone derivatives: a review

Thiazolidinone is considered as a biologically important active scaffold that possesses almost all types of biological activities. Successful introduction of ralitoline as a potent anti-convulsant, etozoline as a antihypertensive, pioglitazone as a hypoglycemic agent and thiazolidomycin activity against streptomyces species proved potential of thiazolidinone moiety. This diversity in the biological response profile has attracted the attention of many researchers to explore this skeleton to its multiple potential against several activities. This review is complementary to earlier reviews and aims to review the work reported on various biological activities of thiazolidinone derivatives from year 2000 to the beginning of 2011. Data are presented for active compounds, some of which have passed the preclinical testing stage.     

Identification of miRNAs in C. roseus and their potential targets

MicroRNAs are small (20-22 nucleotides) none coding, regulatory RNAs, whose pivotal role in gene expression has been associated in number of diseases, therefore prediction of miRNA is an essential yet challenging field. In this study miRNAs of C. roseus are predicted along with their possible target genes. A total of 19,899 ESTs were downloaded from dbEST database and processed and trimmed through SeqClean. Nine sequences were trashed and 31 sequences were trimmed by the program and the resulting sequences were submitted to Repeatmasker and TGICL for clustering and assembly. This contig database was now used to find the putative miRNAs by performing a local BLAST with the miRNAs of B. rapa retrieved from miRBase. The targets were scanned by hybridizing screened ESTs with the UTRs of human using miRanda software. Finally, 7 putative miRNAs were found to hybridize with the various targets of signal transduction and apoptosis that may play significant role in preventing diseases like Leukemia, Arthritis and Alzheimer.     

Dynamics of Major Histocompatibility Complex Class I Association with the Human Peptide-loading Complex

Although the human peptide-loading complex (PLC) is required for optimal major histocompatibility complex class I (MHC I) antigen presentation, its composition is still incompletely understood. The ratio of the transporter associated with antigen processing (TAP) and MHC I to tapasin, which is responsible for MHC I recruitment and peptide binding optimization, is particularly critical for modeling of the PLC. Here, we characterized the stoichiometry of the human PLC using both biophysical and biochemical approaches. By means of single-molecule pulldown (SiMPull), we determined a TAP/tapasin ratio of 1:2, consistent with previous studies of insect-cell microsomes, rat-human chimeric cells, and HeLa cells expressing truncated TAP subunits. We also report that the tapasin/MHC I ratio varies, with the PLC population comprising both 2:1 and 2:2 complexes, based on mutational and co-precipitation studies. The MHC I-saturated PLC may be particularly prevalent among peptide-selective alleles, such as HLA-C4. Additionally, MHC I association with the PLC increases when its peptide supply is reduced by inhibiting the proteasome or by blocking TAP-mediated peptide transport using viral inhibitors. Taken together, our results indicate that the composition of the human PLC varies under normal conditions and dynamically adapts to alterations in peptide supply that may arise during viral infection. These findings improve our understanding of the quality control of MHC I peptide loading and may aid the structural and functional modeling of the human PLC.