Allison H. S. Hall

RNA Interference of Human Papillomavirus Type 18 E6 and E7 Induces Senescence in HeLa Cells

ABSTRACT The human papillomavirus oncoproteins E6 and E7 promote cell proliferation and contribute to carcinogenesis by interfering with the activities of cellular tumor suppressors. We used a small interfering RNA molecule targeting the E7 region of the bicistronic E6 and E7 mRNA to induce RNA interference, thereby reducing expression of E6 and E7 in HeLa cells. RNA interference of E6 and E7 also inhibited cellular DNA synthesis and induced morphological and biochemical changes characteristic of cellular senescence. These results demonstrate that reducing E6 and E7 expression is sufficient to cause HeLa cells to become senescent.

High potency silencing by single-stranded boranophosphate siRNA

In RNA interference (RNAi), double-stranded short interfering RNA (ds-siRNA) inhibits expression from complementary mRNAs. Recently, it was demonstrated that short, single-stranded antisense RNA (ss-siRNA) can also induce RNAi. While ss-siRNA may offer several advantages in both clinical and research applications, its overall poor activity compared with ds-siRNA has prevented its widespread use. In contrast to the poor gene silencing activity of native ss-siRNA, we found that the silencing activity of boranophosphate-modified ss-siRNA is comparable with that of unmodified ds-siRNA. Boranophosphate ss-siRNA has excellent maximum silencing activity and is highly effective at low concentrations. The silencing activity of boranophosphate ss-siRNA is also durable, with significant silencing up to 1 week after transfection. Thus, we have demonstrated that boranophosphate-modified ss-siRNA can silence gene expression as well as native ds-siRNA, suggesting that boranophosphate-modified ss-siRNAs should be investigated as a potential new class of therapeutic agents.

Maternal CD4+ T cells protect against severe congenital cytomegalovirus disease in a novel nonhuman primate model of placental cytomegalovirus transmission

Significance Congenital cytomegalovirus (CMV) is the leading infectious cause of childhood hearing loss and brain damage worldwide. Yet, despite its high prevalence and ranking as a top priority for vaccine development, the immune correlates of protection that could guide vaccine development remain undefined. Using a novel nonhuman primate model of congenital CMV transmission, we demonstrate a critical role for maternal CD4+ T cells in the induction of protective maternal immune responses that prevent fetal demise. In addition to establishing placental CMV transmission for the first time (to our knowledge) in nonhuman primates, this study reveals an association between delayed maternal virus-specific neutralizing antibody responses and severe fetal outcome, providing insight into the mechanism by which maternal CD4+ T cells impact congenital CMV disease. Elucidation of maternal immune correlates of protection against congenital cytomegalovirus (CMV) is necessary to inform future vaccine design. Here, we present a novel rhesus macaque model of placental rhesus CMV (rhCMV) transmission and use it to dissect determinants of protection against congenital transmission following primary maternal rhCMV infection. In this model, asymptomatic intrauterine infection was observed following i.v. rhCMV inoculation during the early second trimester in two of three rhCMV-seronegative pregnant females. In contrast, fetal loss or infant CMV-associated sequelae occurred in four rhCMV-seronegative pregnant macaques that were CD4+ T-cell depleted at the time of inoculation. Animals that received the CD4+ T-cell–depleting antibody also exhibited higher plasma and amniotic fluid viral loads, dampened virus-specific CD8+ T-cell responses, and delayed production of autologous neutralizing antibodies compared with immunocompetent monkeys. Thus, maternal CD4+ T-cell immunity during primary rhCMV infection is important for controlling maternal viremia and inducing protective immune responses that prevent severe CMV-associated fetal disease.

Genes with Bimodal Expression Are Robust Diagnostic Targets that Define Distinct Subtypes of Epithelial Ovarian Cancer with Different Overall Survival

In some cancer types, certain genes behave as molecular switches, with on and off expression states. These genes tend to define tumor subtypes associated with different treatments and different patient survival. We hypothesized that clinically relevant molecular switch genes exist in epithelial ovarian cancer. To test this hypothesis, we applied a bimodal discovery algorithm to a publicly available ovarian cancer expression microarray data set, GSE9891 [285 tumors: 246 malignant serous (MS), 20 endometrioid (EM), and 18 low malignant potential (LMP) ovarian carcinomas]. Genes with robust bimodal expression patterns were identified across all ovarian tumor types and also within selected subtypes: 73 bimodal genes demonstrated differential expression between LMP versus MS and EM; 22 bimodal genes distinguished MS from EM; and 14 genes had significant association with survival among MS tumors. When these genes were combined into a single survival score, the median survival for patients with a favorable versus unfavorable score was 65 versus 29 months (P < 0.0001, hazard ratio = 0.4221). Two independent data sets [high-grade, advanced-stage serous (n = 53) and advanced-stage (n = 119) ovarian tumors] validated the survival score performance. We conclude that genes with bimodal expression patterns not only define clinically relevant molecular subtypes of ovarian carcinoma but also provide ideal targets for translation into the clinical laboratory.

Colonic schwannoma visualized on FDG PET/CT

Abstract:Isolated colonic schwannomas are rare gastrointestinal mesenchymal tumors; only a small number of cases have been reported. The incidence is 2% to 6% of all submucosal tumors of the gastrointestinal tract. They are thought to be distinctive from conventional schwannomas that arise in soft t

Cystic fibrosis involving the cervix, mimicking a well-differentiated adenocarcinoma: a case report.

We describe clinicopathologic and immunohistochemical features of an unusual case of cystic fibrosis manifesting in the cervix as a mass lesion, mimicking cervical adenocarcinoma. A 24-year-old nulligravida with cystic fibrosis developed heavy postcoital vaginal bleeding 4 months after starting oral contraceptives and was found to have a cervical mass. She underwent a loop electrosurgical excision of the mass, and microscopic examination revealed a florid endocervical proliferation, extending to the margins. This lesion was initially interpreted as an invasive, well-differentiated endocervical adenocarcinoma. However, on subsequent review, the lesion was found to have a low rate of proliferation, no evidence of an infiltrative growth pattern, and abundant acute inflammation. Given these findings and the absence of any residual endocervical lesion on a subsequent cold knife conization, we determined that this was a benign, likely reactive, lesion. This case, together with previous studies, suggests that women with cystic fibrosis can develop proliferative endocervical lesions and that oral contraceptives may contribute to their development.

Abstract P6-05-03: Genomic diversity of ductal carcinoma in situ (DCIS) as a driver of invasion and metastasis

Background: Recent evidence indicates that breast cancers may have high levels of heterogeneity. Based on principles of tumor evolution, we are investigating whether DCIS with higher levels of intra-tumoral genetic heterogeneity are more likely to progress to invasive and/or metastatic disease. Methods: Cases (DCIS with co-existing invasive or metastatic cancer) and controls (pure DCIS) are identified from Duke Pathology archives. From cases and controls, we are analyzing two areas of DCIS separated by >1cm with germ line DNA from the same subject to measure allele frequencies of somatic mutations and copy number variation (CNV). Small amounts of FFPE derived DNA are made into NGS libraries for full exome sequencing and hybridization to a 4.2 million element SNP array. Comparison of allele frequencies and CNV is made between specimens from the same cancer to assess heterogeneity. Results: We identified a series of pure DCIS (controls for this study) and generated high coverage sequencing data from 20ng of FFPE DNA from 12 samples (4 subjects, germline + 2 DCIS containing areas from each subject) as proof of principle. We compared the occurrence of deletions, insertions and SNP9s after a 20X coverage filtration. From these data, we identified between 50 to greater than 600 sequence changes in these DCIS compared to normal DNA. Present/absent calls and allele frequencies indicate both significant and variable degrees of heterogeneity even in these pure DCIS samples. Additional data is now being gathered and analyzed based on this established technical approach. Conclusion: We have demonstrated the feasibility of acquiring high quality NGS data from archival DCIS specimens allowing us to test the hypothesis that genetic heterogeneity is a driving force in breast cancer progression. The degree and nature of this heterogeneity will be assessed in a panel of pure DCIS and DCIS co-existing with invasive and/or metastatic cancer. We are now generating and analyzing these data for Symposium presentation. Citation Format: King LM, Marks JR, Hall AH, Temko D, Graham TA, Mardis ER, Maley CC, Hwang E. Genomic diversity of ductal carcinoma in situ (DCIS) as a driver of invasion and metastasis. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P6-05-03.

Optimizing fluorescently-tethered Hsp90 inhibitor dose for maximal specific uptake by breast tumors

Despite improvements in surgical resection, 20-40% of patients undergoing breast conserving surgery require at least one additional re-excision. Leveraging the unique surface expression of heat shock protein 90 (Hsp90), a chaperone protein involved in several key hallmarks of cancer, in breast cancer provides an exciting opportunity to identify residual disease during surgery. We developed a completely non-destructive strategy using HS-27, a fluorescently-tethered Hsp90 inhibitor, to assay surface Hsp90 expression on intact tissue specimens using a fluorescence microendoscope with a field of view of 750 μm and subcellular resolution of 4 μm. HS-27 consists of an FDA approved Hsp90 inhibitor tethered to fluorescein isothiocyanate (EX 488nm, EM 525nm). Here, we optimized ex vivo HS-27 administration in pre-clinical breast cancer models and validated our approach on 21 patients undergoing standard of care ultrasound guided core needle biopsy. HS-27 administration time was fixed at 1- minute to minimize imaging impact on clinical workflow. HS-27 and HS-217 (non-specific control) doses were modulated from 1 μM up to 100 μM to identify the dose maximizing the ratio of specific uptake (HS-27 fluorescence) to non-specific uptake (HS-217 fluorescence). The specificity ratio was maximized at 100 μM and was significantly greater than all other doses (p<0.05). We applied our optimized imaging protocol to clinical samples and demonstrated significantly greater uptake of HS-27 by tumor than non-tumor tissue (p<0.05). The ubiquitous nature of HS-27 binding to all subtypes of breast cancer makes this technology attractive for assessing tumor margins, as one agent can be used for all subtypes.

Intra-tumor molecular heterogeneity in breast cancer: definitions of measures and association with distant recurrence-free survival

PurposeThe purpose of the study was to define quantitative measures of intra-tumor heterogeneity in breast cancer based on histopathology data gathered from multiple samples on individual patients and determine their association with distant recurrence-free survival (DRFS).MethodsWe collected data from 971 invasive breast cancers, from 1st January 2000 to 23rd March 2014, that underwent repeat tumor sampling at our institution. We defined and calculated 31 measures of intra-tumor heterogeneity including ER, PR, and HER2 immunohistochemistry (IHC), proliferation, EGFR IHC, grade, and histology. For each heterogeneity measure, Cox proportional hazards models were used to determine whether patients with heterogeneous disease had different distant recurrence-free survival (DRFS) than those with homogeneous disease.ResultsThe presence of heterogeneity in ER percentage staining was prognostic of reduced DRFS with a hazard ratio of 4.26 (95% CI 2.22–8.18, p < 0.00002). It remained significant after controlling for the ER status itself (p < 0.00062) and for patients that had chemotherapy (p < 0.00032). Most of the heterogeneity measures did not show any association with DRFS despite the considerable sample size.ConclusionsIntra-tumor heterogeneity of ER receptor status may be a predictor of patient DRFS. Histopathologic data from multiple tissue samples may offer a view of tumor heterogeneity and assess recurrence risk.

Leveraging ectopic Hsp90 expression to assay the presence of tumor cells and aggressive tumor phenotypes in breast specimens

Hsp90 has been studied extensively as a therapeutic target in breast cancer in pre-clinical and clinical trials, demonstrating a variety of roles in metastatic progression. The evidence to date suggests a compelling opportunity to leverage attributes of Hsp90 expression beyond therapeutics with potential applications in breast cancer diagnosis, prognosis, and recurrence risk assessment. In this study, we developed a completely non-destructive strategy using HS-27, a fluorescently-tethered Hsp90 inhibitor, to assay Hsp90 expression on intact tissue specimens with comparable contrast to in vivo administration routes, and demonstrate the feasibility of our approach in breast cancer patients. In addition to Hsp90 inhibition being most effective in glycolytic tumors, we found ectopic Hsp90 expression to be highest in glycolytic tumors reinforcing its role as an indicator of aggressive disease. This work sets the stage for immediately using Hsp90 to improve outcomes for breast cancer patients without affecting traditional care pathways.