Granzyme B inhibits vaccinia virus production through proteolytic cleavage of eukaryotic initiation factor 4 gamma 3.

Cytotoxic T lymphocytes (CTLs) are the major killer of virus-infected cells. Granzyme B (GrB) from CTLs induces apoptosis in target cells by cleavage and activation of substrates like caspase-3 and Bid. However, while undergoing apoptosis, cells are still capable of producing infectious viruses unless a mechanism exists to specifically inhibit viral production. Using proteomic approaches, we identified a novel GrB target that plays a major role in protein synthesis: eukaryotic initiation factor 4 gamma 3 (eIF4G3). We hypothesized a novel role for GrB in translation of viral proteins by targeting eIF4G3, and showed that GrB cleaves eIF4G3 specifically at the IESD(1408)S sequence. Both GrB and human CTL treatment resulted in degradation of eIF4G3 and reduced rates of translation. When Jurkat cells infected with vaccinia virus were treated with GrB, there was a halt in viral protein synthesis and a decrease in production of infectious new virions. The GrB-induced inhibition of viral translation was independent of the activation of caspases, as inhibition of protein synthesis still occurred with addition of the pan-caspase inhibitor zVAD-fmk. This demonstrated for the first time that GrB prevents the production of infectious vaccinia virus by targeting the host translational machinery.

Adoption, acceptability, and accuracy of an online clinical trial matching website for breast cancer.

BACKGROUND: Less than 5% of breast cancer patients participate in clinical trials. To increase patients' awareness and access to trials, we created BreastCancerTrials.org, a clinical trial matching website. BreastCancerTrials.org matched patients to trials based on their self-reported breast cancer history. It also provided a messaging platform through which patients could self-refer themselves to participating research sites. OBJECTIVE: To assess adoption by research sites, acceptability to patients, and patients' accuracy in providing information to BreastCancerTrials.org. METHODS: We approached 13 research sites in Northern California to list their trials on BreastCancerTrials.org. For adoption, we examined the willingness of contacted research sites to collaborate with BreastCancerTrials.org. For acceptability, we analyzed usage statistics of visitors who completed the BreastCancerTrials.org health history questionnaire in the first 14 months after launch and surveyed users who visited the website during its first year about their experience. For accuracy, we compared the self-reported health history of 20 patients against their medical records. The health history questionnaire was divided into four sections: About Me, personal information including date of birth and sex; My Health as of Today, current status including cancer stage, menopausal status, and sites with evidence of disease; My Cancer, diagnostic information such as hormone and human epidermal growth factor receptor 2 status; and My Treatment, an itemized record of past treatment including responses to therapy. RESULTS: A total of 12 sites contributed 55 trials. Regarding acceptability, 733 visitors registered on the website; 428 reported their health history; and 407 matched to at least one trial. Of 375 patients who were sent a survey, 75 responded (20%); 23 of the 75 (31%) contacted a research site, 12 of the 23 (52%) were eligible for a trial, and 5 of the 12 (42%) reported enrolling. As for accuracy, 20 clinic visitors reported 1456 health history items, 1324 of which matched their clinic record (90.93%). CONCLUSIONS: BreastCancerTrials.org was adopted by research sites. Patients found it acceptable and were able to provide accurate information for trial matching. Based on our findings, we launched an upgraded version of BreastCancerTrials.org as a national service in October 2008.

A novel lineage-specific hypersensitive site is essential for position independent granzyme B expression in transgenic mice.

The granzyme B gene is activated upon cytotoxic T cell stimulation and the protein is a key inducer of apoptosis in target cells. Previous studies have identified important proximal regulatory regions but these proved insufficient to drive expression in vivo. We identified a DNase1 hypersensitive site (HS2) 3.9kb upstream of the transcription start site that was present in stimulated but not resting CD8+ cells. The CTL line CTLL R8 was stably transfected with GFP reporter constructs and showed consistently higher fluorescence values when HS2 was included. In transgenic mice the presence of the relevant region of DNA resulted in inducible, CTL-specific transcription of the transgene in all transgenic founder lines analyzed. Deletion of HS2 resulted in a 10-fold reduction in expression. This is the first report of a major distal regulatory element in the control of granzyme B transcription.

Design and characterization of a novel human Granzyme B inhibitor.

The intracellular roles of Granzyme B (GrB) in immune-mediated cell killing have been extensively studied. Recent data also implicate GrB in extracellular pathways of inflammation, cytokine activation and autoimmunity. Targeting (GrB) provides a new pharmaceutical agent for various inflammatory disorders. Serpina3n is a mouse extracellular inhibitor of GrB. There is no apparent equivalent in humans. In this study, we used a novel applied genetics approach to engineer a new extracellular GrB serpin. A chimeric protein was generated in which the reactive center loop (RCL) of human extracellular antichymotrypsin (ACT) was replaced with that of serpina3n. This serpin contained 27 amino acid residues from the serpina3n RCL and the remaining 395 residues from human ACT. The insertion converted human ACT into a GrB-inhibitory serpin. Several critical residues were identified by scanning mutagenesis on the chimera and serpina3n. Targeted mutagenesis was conducted on wild-type human ACT by specifically substituting those critical residues, creating a novel inhibitor that contains 99.3% human ACT sequence with only three point mutations. Wild-type human ACT had a kass for GrB of 2.26 × 10(4) M(-1) s(-1), whereas the novel inhibitor binds GrB with a kass of 7.65 × 10(5) M(-1) s(-1). This new drug candidate can be developed in animal models and further tested in clinical trials to help us understand the role of GrB in numerous disorders.

Use of the National Cancer Institute Community Cancer Centers Program screening and accrual log to address cancer clinical trial accrual.

PURPOSE: Screening logs have the potential to help oncology clinical trial programs at the site level, as well as trial leaders, address enrollment in real time. Such an approach could be especially helpful in improving representation of racial/ethnic minority and other underrepresented populations in clinical trials. METHODS: The National Cancer Institute Community Cancer Centers Program (NCCCP) developed a screening log. Log data collected from March 2009 through May 2012 were analyzed for number of patients screened versus enrolled, including for demographic subgroups; screening methods; and enrollment barriers, including reasons for ineligibility and provider and patient reasons for declining to offer or participate in a trial. User feedback was obtained to better understand perceptions of log utility. RESULTS: Of 4,483 patients screened, 18.4% enrolled onto NCCCP log trials. Reasons for nonenrollment were ineligibility (51.6%), patient declined (25.8%), physician declined (15.6%), urgent need for treatment (6.6%), and trial suspension (0.4%). Major reasons for patients declining were no desire to participate in trials (43.2%) and preference for standard of care (39%). Major reasons for physicians declining to offer trials were preference for standard of care (53%) and concerns about tolerability (29.3%). Enrollment rates onto log trials did not differ between white and black (P = .15) or between Hispanic and non-Hispanic patients (P = .73). Other races had lower enrollment rates than whites and blacks. Sites valued the ready access to log data on enrollment barriers, with some sites changing practices to address those barriers. CONCLUSION: Use of screening logs to document enrollment barriers at the local level can facilitate development of strategies to enhance clinical trial accrual.