Hepatitis B and Hepatitis D Viruses: A Comprehensive Update with an Immunological Focus.

Hepatitis B virus (HBV) and hepatitis delta virus (HDV) are highly prevalent viruses estimated to infect approximately 300 million people and 12-72 million people worldwide, respectively. HDV requires the HBV envelope to establish a successful infection. Concurrent infection with HBV and HDV can result in more severe disease outcomes than infection with HBV alone. These viruses can cause significant hepatic disease, including cirrhosis, fulminant hepatitis, and hepatocellular carcinoma, and represent a significant cause of global mortality. Therefore, a thorough understanding of these viruses and the immune response they generate is essential to enhance disease management. This review includes an overview of the HBV and HDV viruses, including life cycle, structure, natural course of infection, and histopathology. A discussion of the interplay between HDV RNA and HBV DNA during chronic infection is also included. It then discusses characteristics of the immune response with a focus on reactions to the antigenic hepatitis B surface antigen, including small, middle, and large surface antigens. This paper also reviews characteristics of the immune response to the hepatitis D antigen (including small and large antigens), the only protein expressed by hepatitis D. Lastly, we conclude with a discussion of recent therapeutic advances pertaining to these viruses.

Targeting the Breast Cancer Kinome.

Protein kinases are highly tractable targets for the treatment of many cancers including breast cancer, due to their essential role in tumor cell proliferation and survival. Sequencing of the breast cancer genome and transcriptome has defined breast cancer as a heterogeneous disease that is classified into five molecular subtypes: luminal A, luminal B, HER2-enriched, basal-like, and claudin-low. Each subtype displays a unique expression profile of protein kinases that can be targeted by small molecule kinase inhibitors or biologics. An understanding of genomic changes, including mutations or copy number variations, for specific protein kinases and dependencies on kinases across breast cancer subtypes is allowing for a more rational design of targeted breast cancer therapies. While specific kinase inhibitors have had success in the clinic, including the CDK4/6 inhibitor palbociclib in combination with aromatase inhibitors in luminal breast cancer, patients often become resistant to treatment. An understanding of the mechanisms allowing cells to bypass targeted kinase inhibition has led to the development of combination therapies that are more durable in pre-clinical studies. However, the heterogeneity of resistance mechanisms and rapid adaptability of the kinome through feedback regulation greatly inhibit the long-term efficacy of combination kinase inhibitor therapies. It is becoming apparent that epigenetic inhibitors, such as HDAC and BET bromodomain inhibitors can block the transcriptional adaptability of tumor cells to kinase inhibitors and prevent the onset of resistance. Such novel combination therapies are currently showing promise in preclinical studies to markedly increase the durability of kinase inhibitors in breast cancer. J. Cell. Physiol. 232: 53-60, 2017. © 2016 Wiley Periodicals, Inc.

Epigenetic inhibition of adaptive bypass responses to lapatinib by targeting BET Bromodomains.

The characterization of kinases as oncogenic drivers has led to more than 30 FDA-approved targeted kinase inhibitors for cancer treatment. Unfortunately, these therapeutics fail to have clinical durability because of adaptive responses from the kinome and transcriptome that bypass inhibition of the targeted pathway. In our recent work, we describe a method to prevent these adaptive responses at an epigenetic level, generating a durable response to kinase inhibition.

Weight loss reduces basal-like breast cancer through kinome reprogramming.

BACKGROUND: Obesity is associated with an aggressive subtype of breast cancer called basal-like breast cancer (BBC). BBC has no targeted therapies, making the need for mechanistic insight urgent. Reducing adiposity in adulthood can lower incidence of BBC in humans. Thus, this study investigated whether a dietary intervention to reduce adiposity prior to tumor onset would reverse HFD-induced BBC. METHODS: Adult C3(1)-Tag mice were fed a low or high fat diet (LFD, HFD), and an obese group initially exposed to HFD was then switched to LFD to induce weight loss. A subset of mice was sacrificed prior to average tumor latency to examine unaffected mammary gland. Latency, tumor burden and progression was evaluated for effect of diet exposure. Physiologic, histology and proteomic analysis was undertaken to determine mechanisms regulating obesity and weight loss in BBC risk. Statistical analysis included Kaplan-Meier and log rank analysis to investigate latency. Student's t tests or ANOVA compared variables. RESULTS: Mice that lost weight displayed significantly delayed latency compared to mice fed HFD, with latency matching those on LFD. Plasma leptin concentrations significantly increased with adiposity, were reduced to control levels with weight loss, and negatively correlated with tumor latency. HFD increased atypical ductal hyperplasia and ductal carcinoma in situ in mammary gland isolated prior to mean latency-a phenomenon that was lost in mice induced to lose weight. Importantly, kinome analysis revealed that weight loss reversed HFD-upregulated activity of PKC-α, PKD1, PKA, and MEK3 and increased AMPKα activity in unaffected mammary glands isolated prior to tumor latency. CONCLUSIONS: Weight loss prior to tumor onset protected against the effects of HFD on latency and pre-neoplastic lesions including atypical ductal hyperplasia and DCIS. Using innovative kinomics, multiple kinases upstream of MAPK/P38α were demonstrated to be activated by HFD-induced weight gain and reversed with weight loss, providing novel targets in obesity-associated BBC. Thus, the HFD-exposed microenvironment that promoted early tumor onset was reprogrammed by weight loss and the restoration of a lean phenotype. Our work contributes to an understanding of underlying mechanisms associated with tumor and normal mammary changes that occur with weight loss.

Inhibition of Lapatinib-Induced Kinome Reprogramming in ERBB2-Positive Breast Cancer by Targeting BET Family Bromodomains.

Therapeutics that target ERBB2, such as lapatinib, often provide initial clinical benefit, but resistance frequently develops. Adaptive responses leading to lapatinib resistance involve reprogramming of the kinome through reactivation of ERBB2/ERBB3 signaling and transcriptional upregulation and activation of multiple tyrosine kinases. The heterogeneity of induced kinases prevents their targeting by a single kinase inhibitor, underscoring the challenge of predicting effective kinase inhibitor combination therapies. We hypothesized that, to make the tumor response to single kinase inhibitors durable, the adaptive kinome response itself must be inhibited. Genetic and chemical inhibition of BET bromodomain chromatin readers suppresses transcription of many lapatinib-induced kinases involved in resistance, including ERBB3, IGF1R, DDR1, MET, and FGFRs, preventing downstream SRC/FAK signaling and AKT reactivation. Combining inhibitors of kinases and chromatin readers prevents kinome adaptation by blocking transcription, generating a durable response to lapatinib, and overcoming the dilemma of heterogeneity in the adaptive response.

Role of HGF in epithelial-stromal cell interactions during progression from benign breast disease to ductal carcinoma in situ.

INTRODUCTION: Basal-like and luminal breast cancers have distinct stromal-epithelial interactions, which play a role in progression to invasive cancer. However, little is known about how stromal-epithelial interactions evolve in benign and pre-invasive lesions. METHODS: To study epithelial-stromal interactions in basal-like breast cancer progression, we cocultured reduction mammoplasty fibroblasts with the isogenic MCF10 series of cell lines (representing benign/normal, atypical hyperplasia, and ductal carcinoma in situ). We used gene expression microarrays to identify pathways induced by coculture in premalignant cells (MCF10DCIS) compared with normal and benign cells (MCF10A and MCF10AT1). Relevant pathways were then evaluated in vivo for associations with basal-like subtype and were targeted in vitro to evaluate effects on morphogenesis. RESULTS: Our results show that premalignant MCF10DCIS cells express characteristic gene expression patterns of invasive basal-like microenvironments. Furthermore, while hepatocyte growth factor (HGF) secretion is upregulated (relative to normal, MCF10A levels) when fibroblasts are cocultured with either atypical (MCF10AT1) or premalignant (MCF10DCIS) cells, only MCF10DCIS cells upregulated the HGF receptor MET. In three-dimensional cultures, upregulation of HGF/MET in MCF10DCIS cells induced morphological changes suggestive of invasive potential, and these changes were reversed by antibody-based blocking of HGF signaling. These results are relevant to in vivo progression because high expression of a novel MCF10DCIS-derived HGF signature was correlated with the basallike subtype, with approximately 86% of basal-like cancers highly expressing the HGF signature, and because high expression of HGF signature was associated with poor survival. CONCLUSIONS: Coordinated and complementary changes in HGF/MET expression occur in epithelium and stroma during progression of pre-invasive basal-like lesions. These results suggest that targeting stroma-derived HGF signaling in early carcinogenesis may block progression of basal-like precursor lesions.