CXCR4 Expression and Treatment With SDF-1? or Plerixafor Modulate Proliferation and Chemosensitivity of Colon Cancer Cells.

CXCR4 Expression and Treatment with SDF-1? or Plerixafor Modulate Proliferation and Chemosensitivity of Colon Cancer Cells.

Transl Oncol. 2013 Apr; 6(2): 124-32
Heckmann D, Maier P, Laufs S, Wenz F, Zeller WJ, Fruehauf S, Allgayer H

Signaling through stromal cell-derived factor-1? (SDF-1?), strongly secreted by bone marrow stromal cells and the CXC chemokine receptor 4 (CXCR4) exposed on tumor cells has pivotal roles in proliferation, metastasis, and tumor cell “dormancy.” Dormancy is associated with cytostatic drug resistance and is probably a property of tumor stem cells and minimal residual disease. Thus, hampering the SDF-1?/CXCR4 cross talk by a CXCR4 antagonist like Plerixafor (AMD3100) should overcome tumor cell dormancy bymobilization of tumor cells from “sanctuary” niches. Our aim was to elucidate the direct effects exerted by SDF-1? and Plerixafor on proliferation, chemosensitivity, and apoptosis of CXCR4-expressing tumor cells.The ability of SDF-1? and Plerixafor to regulate intracellular signaling, proliferation, and invasion was investigated using two colon cancer cell lines (HT-29 and SW480) with either high endogenous or lentiviral expression of CXCR4 compared to their respective low CXCR4-expressing counterparts as a model system. Efficacy of Plerixafor on sensitivity of these cell lines against 5-fluorouracil, irinotecan, or oxaliplatin was determined in a cell viability assay as well as stroma-dependent cytotoxicity and apoptosis assays.SDF-1? increased proliferation, invasion, and ERK signaling of endogenously and lentivirally CXCR4-expressing cells. Exposure to Plerixafor reduced proliferation, invasion, and extracellular signal-regulated kinase 1/2 (ERK1/2) signaling. Combination of chemotherapy with Plerixafor showed an additive effect on chemosensitivity and apoptosis in CXCR4-overexpressing cells. An SDF-1-secreting feeder layer provideda”protective niche” for CXCR4-overexpressing cells resulting in decreased chemosensitivity.CXCR4-antagonistic therapy mobilizes and additionally sensitizes tumor cells toward cytoreductive chemotherapy. HubMed – drug

The influence of 150-cavity binders on the dynamics of influenza a neuraminidases as revealed by molecular dynamics simulations and combined clustering.

PLoS One. 2013; 8(3): e59873
Greenway KT, Legresley EB, Pinto BM

Neuraminidase inhibitors are the main pharmaceutical agents employed for treatments of influenza infections. The neuraminidase structures typically exhibit a 150-cavity, an exposed pocket that is adjacent to the catalytic site. This site offers promising additional contact points for improving potency of existing pharmaceuticals, as well as generating entirely new candidate inhibitors. Several inhibitors based on known compounds and designed to interact with 150-cavity residues have been reported. However, the dynamics of any of these inhibitors remains unstudied and their viability remains unknown. This work reports the outcome of long-term, all-atom molecular dynamics simulations of four such inhibitors, along with three standard inhibitors for comparison. Each is studied in complex with four representative neuraminidase structures, which are also simulated in the absence of ligands for comparison, resulting in a total simulation time of 9.6µs. Our results demonstrate that standard inhibitors characteristically reduce the mobility of these dynamic proteins, while the 150-binders do not, instead giving rise to many unique conformations. We further describe an improved RMSD-based clustering technique that isolates these conformations – the structures of which are provided to facilitate future molecular docking studies – and reveals their interdependence. We find that this approach confers many advantages over previously described techniques, and the implications for rational drug design are discussed. HubMed – drug

Polyanionic Candidate Microbicides Accelerate the Formation of Semen-Derived Amyloid Fibrils to Enhance HIV-1 Infection.

PLoS One. 2013; 8(3): e59777
Tan S, Lu L, Li L, Liu J, Oksov Y, Lu H, Jiang S, Liu S

Polyanionic candidate microbicides, including cellulose sulfate, carrageenan, PRO 2000, were proven ineffective in preventing HIV-1 transmission and even cellulose sulfate showed increased risk of HIV acquisition in the Phase III efficacy trials. Semen plays critical roles in HIV-1 sexual transmission. Specifically, amyloid fibrils formed by fragments of prostatic acidic phosphatase (PAP) in semen termed semen-derived enhancer of virus infection (SEVI) could drastically enhance HIV-1 infection. Here we investigated the interaction between polyanions and PAP248-286, a prototype peptide of SEVI, to understand the possible cause of polyanionic candidate microbicides to fail in clinical trials. We found anionic polymers could efficiently promote SEVI fibril formation, most likely mediated by the natural electrostatic interaction between polyanions and PAP248-286, as revealed by acid native PAGE and Western blot. The overall anti-HIV-1 activity of polyanions in the presence or absence of PAP248-286 or semen was evaluated. In the viral infection assay, the supernatants of polyanions/PAP248-286 or polyanions/semen mixtures containing the free, unbound polyanionic molecules showed a general reduction in antiviral efficacy, while the pellets containing amyloid fibrils formed by the polyanion-bound PAP248-286 showed aggravated enhancement of viral infection. Collectively, from the point of drug-host protein interaction, our study revealed that polyanions facilitate SEVI fibril formation to promote HIV-1 infection, thus highlighting a molecular mechanism underlying the failure of polyanions in clinical trials and the importance of drug-semen interaction in evaluating the anti-HIV-1 efficacy of candidate microbicides. HubMed – drug

Recurrent acute inflammatory demyelinating polyradiculoneuropathy following R-CHOP treatment for non-Hodgkin lymphoma.

Proc (Bayl Univ Med Cent). 2013 Apr; 26(2): 156-8
Liang JJ, Singh PP, Witzig TE

Acute flaccid paralysis following chemotherapy has a wide differential diagnosis, including drug toxicity, acute inflammatory demyelinating polyradiculoneuropathy (AIDP), and malignant nerve infiltration. We present a case of recurrent acute quadriparesis due to AIDP following chemotherapy for non-Hodgkin lymphoma, which resolved each time following administration of intravenous immunoglobulin. Although many chemotherapeutic agents can cause neurologic side effects, such as peripheral neuropathy, drug toxicity as a cause is a diagnosis of exclusion. HubMed – drug