CYP4A in tumor-associated macrophages promotes pre-metastatic niche formation and metastasis

Tumor-associated macrophages (TAMs) play an essential role in metastasis. However, what enables TAMs to have a superior capacity to establish pre-metastatic microenvironment in distant organs is unclear. Here we have begun to uncover the effects of cytochrome P450 (CYP) 4A in TAMs on lung pre-metastatic niche formation and metastasis. CYP4A⁺ TAM infiltration was positively associated with metastasis, pre-metastatic niche formation and poor prognosis in breast cancer patients. The pharmacological inhibition of CYP4A reduced lung pre-metastatic niche formation (evidenced by a decrease in vascular endothelial growth factor receptor 1 positive (VEGFR1⁺) myeloid cell recruitment and pro-metastatic protein expression) and metastatic burden, accompanied with TAM polarization away from the M2 phenotype in spontaneous metastasis models of 4T1 breast cancer and B16F10 melanoma. Co-implantation of 4T1 cells with CYP4A10^high macrophages promoted lung pre-metastatic niche formation and metastasis. Depletion of TAMs disrupted lung pre-metastatic niches and thereby prevented metastasis. Treatment with the CM from CYP4A10^high M2 macrophages (M2) increased pre-metastatic niche formation and metastatic burden in the lungs, whereas CYP4A inhibition attenuated these effects. In vitro TAM polarization away from the M2 phenotype induced by CYP4A inhibition decreased VEGFR1⁺ myeloid cell migration and fibronectin expression, accompanied with downregulation of STAT3 signaling. Conversely, overexpression of CYP4A or exogenous addition of 20-hydroxyeicosatetraenoic acid promoted M2 polarization and cytokine production of macrophages and thereby enhanced migration of VEGFR1⁺ myeloid cells, which were reversed by siRNA or pharmacological inhibition of STAT3. Importantly, a combined blocking M2 macrophage-derived factors TGF-β, VEGF and SDF-1 abolished VEGFR1⁺ myeloid cell migration and fibroblast activation induced by CYP4A. In summary, CYP4A in TAMs is crucial for lung pre-metastatic niche formation and metastasis, and may serve as a potential therapeutic target in human cancer.

Production and Directional Evolution of Antisarafloxacin ScFv Antibody for Immunoassay of Fluoroquinolones in Milk

A recombinant antisarafloxacin ScFv antibody was produced by direct transformation of its gene into Rosetta-gami(DE3) for expression, and then its recognition mechanisms for 12 fluoroquinolones were studied using the molecular docking method. On the basis of the results of virtual mutation, the ScFv antibody was evolved by directional mutagenesis of contact amino acid residue Tyr99 to His. The ScFv mutant showed highly increased affinity for the 12 drugs with up to sevenfold improved sensitivity. Finally, the mutant was used to develop an indirect competitive enzyme linked immunosorbent assay for determination of the 12 drugs in milk. The limits of detection were in the range of 0.3-8.0 ng/mL; the ties were in the range of 5-106%, and the recoveries from the standard fortified blank milk were in the range of 62.0-89.3%. This is the first study reporting the evolution of an ScFv antibody using a directional mutagenesis strategy based on virtual mutation.

Correlation between magnetic resonance perfusion weighted imaging of radiation brain injury and pathology

We used magnetic resonance perfusion weighted imaging and pathological evaluation to examine different stages of radiation-induced brain injury and to investigate the correlation between the relative cerebral blood volume (rCBV) ratio and vascular endothelial growth factor (VEGF). Thirty adult rats were randomly divided into 2 groups: control and radiation group. The control group was not subjected to irradiation. The irradiation group rats were examined by magnetic resonance imaging and magnetic resonance perfusion weighted imaging at 1, 3, 6, 9, and 12 months after radiation treatment. We measured the rCBV, mean transit time, and time to peak. Hematoxylin and eosin staining, immunohistochemical staining, and electron microscopy were performed. VEGF absorbance was evaluated by immunohistochemical staining. Compared with the control group, the differences in rCBV, mean transit time, time to peak, and VEGF absorbance after 3 months were statistically significant (P < 0.05). rCBV was positively correlated with VEGF (r = 0.94, P < 0.05). Magnetic resonance perfusion weighted imaging can reflect pathophysiological changes in brain tissue after irradiation. Decreased expression of VEGF plays a critical role in the pathogenesis of radiation-induced brain injury.