Objectives

A growing body of evidence supports a role for thrombocytosis in the promotion of epithelial ovarian cancer biology. However, studies have only linked preoperative platelet count at time of initial cytoreductive surgery to clinical outcome. Here, we sought to determine the impact of elevated platelet count at time of secondary cytoreductive surgery (SCS) for recurrent disease.

Methods

Under an IRB-approved protocol, we identified 107 women with invasive epithelial ovarian cancer who underwent SCS between January 1997 and June 2012. We reviewed clinical, laboratory, and pathologic records from this retrospective cohort. The data was analyzed using the chi-squared, Fisher's exact, Cox proportional hazards, and Kaplan-Meier tests. We defined thrombocytosis as a platelet count ≥ 350 × 10(9)/L and optimal resection at SCS as microscopic residual disease.

Results

Thirteen of 107 women (12%) with recurrent ovarian cancer had thrombocytosis prior to SCS. Preoperative thrombocytosis at SCS was associated with failure to undergo optimal resection (p=0.0001). Women with preoperative thrombocytosis at time of SCS demonstrated shorter overall survival (33 months) compared to those with normal platelet counts (46 months, p=0.004). On multivariate analysis, only preoperative platelet count retained significance as an independent prognostic factor (p=0.025) after controlling for age at SCS (p=0.90), disease free interval from primary treatment (0.06), and initial stage of disease (0.66).

Conclusions

Elevated platelet count at time of SCS is associated with suboptimal resection and shortened overall survival. These data provide further evidence supporting a plausible role for thrombocytosis in aggressive ovarian tumor biology.

Expansion microscopy (ExM) increases the effective resolving power of any microscope by expanding the sample with swellable hydrogel. Since its invention, ExM has been successfully applied to a wide range of cell, tissue, and animal samples. Still, fluorescence signal loss during polymerization and digestion limits molecular-scale imaging using ExM. Here, we report the development of label-retention ExM (LR-ExM) with a set of trifunctional anchors that not only prevent signal loss but also enable high-efficiency labeling using SNAP and CLIP tags. We have demonstrated multicolor LR-ExM for a variety of subcellular structures. Combining LR-ExM with superresolution stochastic optical reconstruction microscopy (STORM), we have achieved molecular resolution in the visualization of polyhedral lattice of clathrin-coated pits in situ.

Natural products serve as chemical blueprints for most antibiotics in clinical use. The evolutionary process by which these molecules arise is inherently accompanied by the co-evolution of resistance mechanisms that shorten the clinical lifetime of any given class of antibiotics¹. Virginiamycin acetyltransferase (Vat) enzymes are resistance proteins that provide protection against streptogramins², potent antibiotics against Gram-positive bacteria that inhibit the bacterial ribosome³. Owing to the challenge of selectively modifying the chemically complex, 23-membered macrocyclic scaffold of group A streptogramins, analogues that overcome the resistance conferred by Vat enzymes have not been previously developed². Here we report the design, synthesis, and antibacterial evaluation of group A streptogramin antibiotics with extensive structural variability. Using cryo-electron microscopy and forcefield-based refinement, we characterize the binding of eight analogues to the bacterial ribosome at high resolution, revealing binding interactions that extend into the peptidyl tRNA-binding site and towards synergistic binders that occupy the nascent peptide exit tunnel. One of these analogues has excellent activity against several streptogramin-resistant strains of Staphylococcus aureus, exhibits decreased rates of acetylation in vitro, and is effective at lowering bacterial load in a mouse model of infection. Our results demonstrate that the combination of rational design and modular chemical synthesis can revitalize classes of antibiotics that are limited by naturally arising resistance mechanisms.