Novel Biomarkers Of Response Research Articles

Abstract 509: Novel role of MeCP2 in response to EGFR targeted therapy

Abstract One of the targets towards the development of new agents to combat cancer is the inhibition of epidermal growth factor receptor (EGFR). A therapeutic antibody to EGFR, cetuximab, is seen to be effective in combination with cisplatin or radiation. However, only one out of four patients treated benefit from this therapy. It is therefore important to identify patients who can gain from this treatment. We hypothesize that through phosphoproteome analysis, we can identify alterations in novel signal transduction molecule(s) induced by cetuximab treatment in sensitive cell lines or TMA that will predict response to treatment. Phosphoproteomic changes upon cetuximab treatment in UMSCC-1 (cetuximab-responsive) and UMSCC-74B (cetuximab-non-responsive) cell lines using nonporous silica reverse-phase high performance liquid chromatography (NPS-RP-HPLC) were assessed. To confirm the results of phosphoproteomics data, three proteins that were seen to be affected in the sensitive cell line were investigated by immunoprecipitating total proteins followed by immunoblotting with phospho-specific antibodies. We found pharmacodynamic changes in 12 novel proteins upon cetuximab treatment in UMSCC-1 cell line. By Immunoblotting, we confirmed that these three proteins (methyl-CpG binding proteins) are indeed phosphorylated at serine, threonine and tyrosine sites. Cetuximab treatment in UMSCC-1, induced phosphorylation of NCoR1 and MeCP2 (which cause transcriptional repression) and decreased phosphorylation of MBD2 (which causes transcriptional activation), thus confirming the phosphoproteomic data. In contrast, the phosphoproteomics data in UMSCC-74B indicated either no effect or an opposing effect to that seen in the sensitive cells. These data suggest that we have a powerful strategy to identify novel phosphoproteins that are affected by EGFR inhibition and thus, novel biomarkers of response to cetuximab. These and additional biomarkers that we hope to discover will undergo rigorous in vitro and in vivo testing before employing them on TMA from xenografts. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 509.

Peripheral Blood Mononuclear Cells as a Model to Study the Response of Energy Homeostasis-Related Genes to Acute Changes in Feeding Conditions

Peripheral blood mononuclear cells (PBMCs) are readily accessible biological material and a potential tissue source to discover novel biomarkers of response to environmental exposures including nutrition. We analyzed whether PBMCs could reflect molecular changes that take place in response to different feeding conditions in key organs/tissues involved in energy homeostasis. We studied energy balance-related genes whose expression was altered in normoweight (control) rats and in diet-induced (cafeteria) obese rats in response to ad libitum feeding, 14-h fasting, and 6-h refeeding after fasting, using whole-genome microarray analysis. In PBMCs, the expression of the genes central to energy metabolism was altered by the feeding conditions. The number of affected genes was 75 in the control rats, but only 23 in the cafeteria obese rats. Most of these genes play a role in metabolic pathways regulated by nutritional changes, such as lipid metabolism (the metabolic pathway mainly reflected in blood cells), carbohydrate metabolism, central energy metabolism, respiratory chain/mitochondrial ATPase system, and food intake regulation. Importantly, our results showed a similar behavior to that of the mesenteric white adipose tissue. In conclusion, metabolic adaptations to acute changes in feeding conditions are reflected in the expression of genes central to energy homeostasis in PBMCs of normoweight rats, while response is impaired in cafeteria obese animals. The lower number of genes affected in obese animals indicates impaired nutritional regulation. PBMCs appear as a suitable potential model to characterize metabolic adaptations to food intake and body weight maintenance in experimental animals. These findings may also inform the development of future peripheral tissue models in the emerging field of clinical nutrigenomics.

Differential Methylation Profile of Ovarian Cancer in Tissues and Plasma

An accurate biomarker for detection of ovarian cancer may reduce cancer-related mortality. Using a previously developed microarray-based technique, we evaluated differences in DNA methylation profiles in a panel of 56 genes using sections of serous papillary adenocarcinomas and uninvolved ovaries (n=30) from women in a high-risk group. Methylation profiles were also generated for circulating DNA from blood of patients (n=33) and healthy controls (n=33). Using the most differentially methylated genes for naïve Bayesian analysis, we identified ten of these profiles as potentially informative in tissues. Various combinations of these genes produced 69% sensitivity and 70% specificity for cancer detection as estimated under a stratified, fivefold cross-validation protocol. In plasma, five genes were identified as informative; their combination had 85% sensitivity and 61% specificity for cancer detection. These results suggest that differential methylation profiling in heterogeneous samples has the potential to identify components of a composite biomarker that may detect ovarian cancer in blood with significant accuracy.

Circulating cell-free DNA: A novel biomarker for response to therapy in ovarian carcinoma

Introduction: Cell-free DNA (CFDNA) is a reflection of both normal and tumor-derived DNA released into the circulation through cellular necrosis and apoptosis. We sought to determine whether tumor-specific plasma DNA could be used as a biomarker for tumor burden and response to therapy in an orthotopic ovarian cancer model. Methods: Female nude mice injected intraperitoneally with HeyA8 ovarian cancer cells were treated with either docetaxel alone or in combination with anti-angiogenic agents (AEE788 -- dual VEGFR and EGFR antagonist or EA5 – monoclonal antibody against ephrin A2). Following DNA extraction from plasma, quantification of tumor-specific DNA was performed by real-time PCR using human specific beta-actin primers. The number of genome equivalents (GE/ml) were determined from a standard curve. Apoptosis was assessed by TUNEL staining of treated tumors. Results: The levels of tumor-specific DNA in plasma increased progressively with increasing tumor burden (R2=0.8, p