Thomas Broudy

We found that when group A streptococci are cocultured with human pharyngeal cells, they upregulate and secrete a 25-kDa toxin, determined to be the bacteriophage-encoded streptococcal pyrogenic exotoxin C (SpeC). This prompted us to determine if the bacteriophage themselves are induced during coculture conditions. We found that bacteriophage induction does occur, resulting in the release of approximately 10(5) phage particles during the 3-h coculture. Furthermore, we show that the bacteriophage induction event is mediated by a pharyngeal cell soluble factor for which we provide an initial characterization.

The role lysogenic bacteriophage play in the pathogenesis of the host bacterium is poorly understood. In a previous study, we found that streptococcal coculture with human pharyngeal cells resulted in the induction of lysogenic bacteriophage as well as the phage-associated streptococcal pyrogenic exotoxin C (SpeC). In this study, we have determined that in addition to SpeC induction, a number of other streptococcal proteins are also released by the bacteria during coculture with pharyngeal cells. Among these, we identified and characterized a novel 27-kDa secreted protein. Sequence analysis of this novel protein demonstrated it to be encoded by the same lysogenic bacteriophage which harbors speC. Protein sequence analysis revealed varied homologies with several streptococcal DNases. Further biochemical characterization of the recombinantly expressed protein verified it to be a divalent cation-dependent streptococcal phage-encoded DNase (Spd1). Although functionally distinct, SpeC and Spd1 are associated by a number of parameters, including genetic proximity and transcriptional regulation. Finally, we speculate on the induction of phage-encoded DNase (Spd1) enhancing the fitness of both bacteria and phage.

Temperate bacteriophage can transfer toxin-encoding genes between bacteria, often resulting in acquired pathogenicity. However, little is known regarding the effects of the eukaryotic host on the phage-pathogen interaction. Using Streptococcus pyogenes as a model, we demonstrate, both in vitro and in vivo, that the eukaryote mediates the efficient induction of toxin-encoding temperate phage and the resultant conversion of Tox(-) flora to Tox(+). Furthermore, we show that both phage induction and subsequent conversion need not happen in the same mammalian host, as host-to-host phage transmission can result in toxigenic conversion within the secondary host. Ultimately, our findings demonstrate that the eukaryotic host serves as an essential component in the phage-mediated evolution of virulence within the microbial population.

Abstract Fibrolamellar hepatocellular carcinoma (FL-HCC) is a rare and distinct primary hepatic malignancy that has conventionally been considered to be a histologic variant of hepatocellular carcinoma. However, it has more recently been recognized as a distinct clinical entity with respect to its epidemiology and prognosis. The etiology of FL-HCC is unclear and there is no clinical or histological evidence for association with chronic liver disease. Recent genetic studies have identified the fusion gene DNAJB1-PRKACA as a recurrent genetic lesion in the disease. Molecular pathogenesis of FL-HCC; however, is not well understood and has been reported to occur in association with focal nodular hyperplasia. Overexpression of genes in PIK3, MAPK and RAS pathways is observed in FL-HCC and in contrast to viral-associated HCC, epigenetic instability is rare in FL-HCC. Here we describe development of a novel FL-HCC Patient Derived Xenograft (PDX) model LI5132. RNASeq analysis revealed presence of DNAJB1-PRKACA gene fusion on chromosome 19, a molecular signature of FL-HCC. Clinical diagnosis as HCC of fibrolamellar type was confirmed by H&E staining in the PDX tumor. The PDX tumor had a distinctive intratumoral fibrosis with a lamellar pattern. PDX model was established by inoculating patient tumor cells subcutaneously in NOD-SCID mice. Robust tumor growth was observed with a 100% take rate in NOD-SCID mice. To evaluate the translational relevance of this model toward therapeutic development, the efficacy of a novel multi-target Aurora kinase A and angiokinase inhibitor, ENMD-2076, was evaluated in a therapeutic mode in this model. ENMD-2076 showed significant efficacy in suppressing tumor growth in NOD-SCID mice, at the 200 mg/kg dose evaluated in this study. Weight loss observed during the treatment period could not be attributed to ENMD-2076 as it was similar to weight loss observed with vehicle treatment. ENMD-2076 has now progressed in to phase II trials in the clinic for treatment of FL-HCC. This demonstrates the translational utility of this FL-HCC model in development of anti-cancer therapeutic agents. Citation Format: Jayant Thatte, Elvira C. Talaoc, Colleen Scott, Ken Ren, Thomas Broudy. Kinase inhibitor demonstrates efficacy in patient derived xenograft model of fibrolamellar hepatocellular carcinoma featuring DNAJB1-PRKACA gene fusion [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4203. doi:10.1158/1538-7445.AM2017-4203