The CCR5 chemokine receptor acts as a co-receptor for HIV-1 viral entry. Here we report the 2.7 Å resolution crystal structure of human CCR5 bound to the marketed HIV drug Maraviroc. The structure reveals a ligand binding site that is distinct from the proposed major recognition sites for chemokines and the viral glycoprotein gp120, providing insights into the mechanism of allosteric inhibition of chemokine signaling and viral entry. A comparison between CCR5 and CXCR4 crystal structures, along with models of co-receptor/gp120-V3 complexes, suggests that different charge distributions and steric hindrances caused by residue substitutions may be major determinants of HIV-1 co-receptor selectivity. These high-resolution insights into CCR5 can enable structure-based drug discovery for the treatment of HIV-1 infection.

Small molecules are known to stabilise membrane proteins and to modulate function and oligomeric state, but their identity is often hard to define. Here we develop and apply a high-resolution, Orbitrap mass spectrometer for intact membrane protein-ligand complexes. Using this platform we resolve the complexity of multiple binding events, quantify small molecule binding and reveal selectivity for endogenous lipids that differ only in acyl chain length.

Estrogen independence and progression to a metastatic phenotype are hallmarks of therapeutic resistance and mortality in breast cancer patients. Metastasis has been associated with chemokine signaling through the SDF-1–CXCR4 axis. Thus, the development of estrogen independence and endocrine therapy resistance in breast cancer patients may be driven by SDF-1–CXCR4 signaling. Here we report that CXCR4 overexpression is indeed correlated with worse prognosis and decreased patient survival irrespective of the status of the estrogen receptor (ER). Constitutive activation of CXCR4 in poorly metastatic MCF-7 cells led to enhanced tumor growth and metastases that could be reversed by CXCR4 inhibition. CXCR4 overexpression in MCF-7 cells promoted estrogen independence in vivo, whereas exogenous SDF-1 treatment negated the inhibitory effects of treatment with the anti-estrogen ICI 182,780 on CXCR4-mediated tumor growth. The effects of CXCR4 overexpression were correlated with SDF-1–mediated activation of downstream signaling via ERK1/2 and p38 MAPK (mitogen activated protein kinase) and with an enhancement of ER-mediated gene expression. Together, these results show that enhanced CXCR4 signaling is sufficient to drive ER-positive breast cancers to a metastatic and endocrine therapy-resistant phenotype via increased MAPK signaling. Our findings highlight CXCR4 signaling as a rational therapeutic target for the treatment of ER-positive, estrogen-independent breast carcinomas needing improved clinical management.

The chemokine receptor CCR5 plays a vital role in immune surveillance and inflammation. However, molecular details that govern its endogenous chemokine recognition and receptor activation remain elusive. Here we report three cryo-electron microscopy structures of Gi1 protein-coupled CCR5 in a ligand-free state and in complex with the chemokine MIP-1α or RANTES, as well as the crystal structure of MIP-1α-bound CCR5. These structures reveal distinct binding modes of the two chemokines and a specific accommodate pattern of the chemokine for the distal N terminus of CCR5. Together with functional data, the structures demonstrate that chemokine-induced rearrangement of toggle switch and plasticity of the receptor extracellular region are critical for receptor activation, while a conserved tryptophan residue in helix II acts as a trigger of receptor constitutive activation.

No abstract

Methylated SEPT9 showed relatively low sensitivity in detecting early stage colorectal cancer (CRC) and advanced adenomas (AA) in plasma. Combination of multiple biomarkers was an effective strategy to improve sensitivity in early stage cancer diagnosis and screening. A new qPCR‐based assay combining the detection of methylated SEPT9 and SDC2 (ColoDefense test) was used. Methylation statuses of SEPT9 and SDC2 were examined in 40 sets of cancer tissues and paired adjacent tissues, 10 adenomatous polyps and 3 hyperplastic polyps (HP). Then evaluated with 384 plasma samples, including 117 CRC patients, 23 AA patients, 78 small polyps patients, and 166 normal individuals. The limit of detection of ColoDefense was about 25 pg per reaction. Both SEPT9 and SDC2 were shown by ColoDefense to be heavily methylated in CRC tissues when compared to paired paracancerous tissues and HP (P < .01). The sensitivities for detecting AA and stage I CRC by plasma SEPT9 methylation alone were 12.1% and 65.0%, and those by plasma SDC2 methylation alone were 43.5% and 55.0%. In comparison, the sensitivities to detect AA and stage I CRC by ColoDefense improved to 47.8% and 80.0%. The overall sensitivity of ColoDefense in detecting CRC was 88.9% (95% CI: 81.4%‐93.7%) with a specificity of 92.8% (95% CI: 87.4%‐96.0%). Detection of the combinatorial biomarker of methylated SEPT9 and/or SDC2 is a powerful, convenient and highly effective strategy for early CRC screening with high sensitivity and specificity.

Drug binding to the P2Y1 receptor prevents phosphorylation and competes with an endogenous ligand.

Current nanodrug-based cancer therapy is susceptible to the problems of rapid clearance from circulation and limited therapeutic efficacy. Herein, we report a magnetically targeted and photothermal-triggered drug release nanotheranostics system based on superparamagnetic iron oxide (Fe3O4), IR780, doxorubicin (DOX), and perfluoropentane (PFP) entrapped poly-lactide-co-glycolide (PLGA) nanoparticles (IR780/Fe3O4@PLGA/PFP/DOX NPs) for triple-modal imaging-guided synergistic therapy of breast cancer. In this work, IR780 and Fe3O4 convert light into heat, which triggers DOX release from IR780/Fe3O4@PLGA/PFP/DOX NPs and a phase-shift thermoelastic expansion of PFP; this procedure further accelerates the DOX release and tissue extrusion deformation. Fe3O4 NPs also serve as the target moiety by an external magnet directed to the tumor. Specifically, the IR780/Fe3O4@PLGA/PFP/DOX NPs can be used for triple-modal imaging, including near infrared fluorescence, magnetic resonance, and ultrasound. Furthermore, the antitumor therapy studies reveal the extraordinary performance of IR780/Fe3O4@PLGA/PFP/DOX NPs in magnetically targeted synergistic chemo-photothermal therapy of cancer. Therefore, the multifunctional IR780/Fe3O4@PLGA/PFP/DOX NPs guided by the magnetic field show a great potential for cancer theranostics.