Abrogated Response to Cellular Stress Identifies DCIS Associated with Subsequent Tumor Events and Defines Basal-like Breast Tumors

SummaryApproximately 15%–30% of women diagnosed with ductal carcinoma in situ (DCIS) develop a subsequent tumor event within 10 years after surgical lumpectomy. To date, little is known about the molecular pathways that confer this differential risk for developing subsequent disease. In this study, we demonstrate that expression of biomarkers indicative of an abrogated response to cellular stress predicts DCIS with worse outcome and is a defining characteristic of basal-like invasive tumors. Mechanistic studies identify the Rb pathway as a key regulator of this response. Conversely, biomarkers indicative of an intact response to cellular stress are strongly associated with a disease-free prognosis. Assessment of these biomarkers in DCIS begins to allow prediction of tumor formation years before it actually occurs

All is not lost: learning from 9p21 loss in cancer

The cancer research community continues to search for additional biomarkers of response and resistance to immune checkpoint treatment (ICT). The ultimate goal is to direct the use of ICT in patients whose tumors are most likely to benefit to achieve a refinement that is equivalent to that of a genotype-matched targeted treatment. Dissecting the mechanisms of ICT resistance can help us characterize ICT nonresponders more efficiently. In this opinion, we argue that there may be additional knowledge gained about immune evasion in cancer by analyzing the loss of the human 9p21.3 locus; as an example, we highlight findings of 9p21.3 loss from the investigator-initiated, pan-cancer INSPIRE study, in which patients were treated with pembrolizumab (anti-PD-1 antibody) ICT

Premalignant breast neoplasia: a paradigm of interlesional and intralesional molecular heterogeneity and its biological and clinical ramifications.

As is well established in invasive breast disease, it is becoming increasingly clear that molecular heterogeneity, both between and within lesions, is a prevalent, distinct phenotype of premalignant lesions of the breast. Key pathways of tumorigenesis modulate critical features of premalignant lesions such as proliferation, differentiation, stress response, and even the generation of diversity. Current studies show that evaluation of these lesions may provide clinically useful information on future tumor formation as well as biological insights into the origin and functional significance of this distinct phenotype

Abstract 333: The role of the retinoblastoma pathway (Rb) in high grade serous ovarian varcinoma (HGSC)

Abstract The Rb pathway functions as a cell cycle checkpoint and deregulation of its components, commonly found in malignancies, causes progression from G1 to S phase, promoting cellular proliferation. Because of Rb's central role in checkpoint regulation, abrogation of the pathway can occur through multiple non-redundant mechanisms including Rb loss, hypermethylation or mutation, and CCND1 or CCNE amplification. Emerging evidence shows that tumour types can often be distinguished by particular alterations in one member of the pathway suggesting that different mechanisms of Rb abrogation may regulate tumour behaviour. We hypothesize that Rb pathway deregulation is frequent in HGSC, the most common and most aggressive histotype of ovarian cancer, and that the mechanism of Rb pathway deregulation identifies clinically distinct subgroups of HGSC. Micro-dissected epithelium from HGSC and normal FTE samples were analyzed for differential gene expression using the Affymetrix U133 Plus 2.0 gene-chips, and expression values for p53, p21, p27, p16, CCND1, CCNE and Rb genes determined. Protein expression was assessed by immunohistochemistry (IHC) on tissue microarrays composed of ovarian/tubal carcinomas inclusive of the major histotypes. Digitized stained slides were quantified using automated image analysis and correlated with clinico-pathologic variables including outcome. Rb loss of heterozygosity (LOH) was tested by an Rb diagnostics protocol involving D13S153 and RB1.2 polymorphic marker analyses using PCR amplification, followed by comparisons of the tumour and its corresponding normal sample by MicroGene Clipper sequencers. Gene expression analysis showed statistically significant over-expression of p53, CCNE E2F1/3 and p16 and down-regulation of p21 and CCND1 in HGSC compared to normal fallopian tube epithelium (p<0.001). Protein expression determined by IHC analysis of HGSC revealed a similar pattern of expression when compared to normal fallopian tube, the site of origin of this carcinoma. There were important differences in the expression of these proteins between HGSC subgroups, where up-regulation was observed for p16, CCNE, CCND1 and BIRC5 in 58.3%, 57%, 33.3%, and 58.3% respectively. Rb however, showed no statistically significant differences at the RNA level, but 40% of all HGSC profiled had a significant decrease in protein expression. Interestingly, LOH analysis revealed 76% of HGSC had Rb inactivation at the gene level. Furthermore, we observed statistically significant correlations (p=0.029) between p16 over-expression and Rb protein loss, using Fisher's Exact test. HGSC is characterized by both genetic and protein abrogation in the Rb pathway. Additionally, we observed differences in the mechanism of this G1/S checkpoint inactivation amongst HGSC patient samples which may represent important biological/clinical differences amongst sub-groups of serous cancer patients. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 333. doi:10.1158/1538-7445.AM2011-33

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Glycogen-targeting subunits of protein phosphatase-1, such as protein targeting to glycogen (PTG), direct the phosphatase to the glycogen particle, where it stimulates glycogenesis. We have investigated the metabolic impact of overexpressing PTG in liver of normal rats. After administration of PTG cDNA in a recombinant adenovirus, animals were fasted or allowed to continue feeding for 24 hours. Liver glycogen was nearly completely depleted in fasted control animals, whereas glycogen levels in fasted or fed PTG-overexpressing animals were 70% higher than in fed controls. Nevertheless, transgenic animals regulated plasma glucose, triglycerides, FFAs, ketones, and insulin normally in the fasted and fed states. Fasted PTG-overexpressing animals receiving an oral bolus of [U-13 C]glucose exhibited a large increase in hepatic glycogen content and a 70% increase in incorporation of [ 13 C]glucose into glycogen. However, incorporation of labeled glucose accounted for only a small portion of the glycogen synthesized in PTG-overexpressing animals, consistent with our earlier finding that PTG promotes glycogen synthesis from gluconeogenic precursors. We conclude that hepatic PTG overexpression activates both direct and indirect pathways of glycogen synthesis. Because of its ability to enhance glucose storage without affecting other metabolic indicators, the glycogen-targeting subunit may prove valuable in controlling blood glucose levels in diabetes