A biomarker panel and psychological morbidity differentiates the irritable bowel syndrome from health and provides novel pathophysiological leads

BACKGROUNDS

The development of a reliable biomarker for irritable bowel syndrome (IBS) remains one of the major aims of research in functional gastrointestinal disorders (FGIDs) and is complicated by the absence of a perfect reference standard. Previous efforts based on genetic and immune markers have showed promise, but have not been robust.

AIM

To evaluate an extensive panel of gene expression and serology markers combined with psychological measures in differentiating IBS from health and between subtypes of IBS.

METHODS

Of subjects eligible for analysis (N = 244), 168 met criteria for IBS (60 IBS-C, 57 IBS-D and 51 mixed), while 76 were free of any FGID. A total of 34 markers were selected based on pathways implicated in pathophysiology of IBS or whole human genome screening. Psychological measures were recorded that covered anxiety, depression and somatisation. Models differentiating disease and health were based on unconditional logistic regression and performance assessed through area under the receiver-operator characteristic curve (AUC), sensitivity and specificity.

RESULTS

The performance of a combination of 34 markers was good in differentiating IBS from health (AUC = 0.81) and was improved considerably with the addition of four psychological markers (combined AUC = 0.93). Of the 34 markers considered, discrimination was derived largely from a small subset. Good discrimination was also obtained between IBS subtypes with the best being observed for IBS-C vs. IBS-D (AUC = 0.92); however, psychological variables provided almost no incremental discrimination subtypes over biological markers (combined AUC = 0.94).

CONCLUSIONS

A combination of gene expression and serological markers in combination with psychological measures shows exciting progress towards a diagnostic test for IBS compared with healthy subjects, and to discriminate IBS-C from IBS-D.

Abstract P4-06-08: Clinical utility of functional analysis of FGFR kinase family for selecting patients who may benefit from FGFR inhibitors

Background: Fibroblast growth factor receptor (FGFR) family of receptor tyrosine kinases (RTKs) are currently under investigation as therapeutic targets for the treatment of breast cancer. Members of this kinase family have been associated with breast cancer progression and resistance to current therapeutics. FGFR1 amplifications range from 7.5–17% in breast cancers and are associated with a shorter overall survival. FGFR1 amplified cell lines drive activation of AKT, ERK, and RSK and are highly sensitive to FGFR1 inhibition, suggesting an oncogenic addiction to FGFR1. FGFR2 is activated in lapatinib-resistant, HER2-positive cells. Likewise, FGFR3 expression levels are elevated in tamoxifen-resistant, ER positive patients. FGFR 4 overexpression correlated with poor response to chemotherapy due to activation of MAPK and increase in B-cell lymphoma extra large (BCL-XL) levels. Using an immuno-microarray system, this study seeks to determine FGFR signal transduction pathway modulation post FGFR inhibitor treatment in breast cancer cell lines expressing varying levels of FGFR1, 2, 3 or 4.

Method: FGFR 1, 2, 3, and 4 amplified cell lines (MDA-MB-134VI (KRAS), SNU16, RT112, and MDA-MB-453) were treated with varying dosages (1, 10, 100, and 1000nM) of several FGFR inhibitors (AZD4547 (pan FGFR), PD173074 (FGFR1,3) and Ponatinib-AP24534 (FGFR1)) either in presence or absence of corresponding FGF (FGF1, FGF7, FGF9, and FGF19) stimulation. Expression and activation of FGFR 1, 2, 3, and 4 and downstream signaling proteins FRS2, AKT, ERK, MEK, and RSK were measured utilizing a proximity based immuno-microarray.

Results: FGFR1, 2, 3, 4 protein expression was detected in each of the corresponding four FGFR1, 2, 3, 4 amplified cell lines. Total protein levels remained unchanged with or without FGFs stimulation. Levels of FGFR1 phosphorylation increased 5 folds in MDA-MB-134VI stimulated with FGF1. FGFR2 and FGFR3 activation increased by 2–3 folds in SNU16 and RT112 stimulated with FGF7, and FGF9 respectively. FGFR4 activation levels in MDA-MB-453 remained unchanged due to Y367C mutation. ERK was activated in both FGF1 stimulated and unstimulated group in MDA-MB134 due to the KRAS mutation. RSK activation increased in both SNU16 and RT112 when stimulated with FGF7, and FGF9 respectively. FGFR inhibitors treated data analysis is currently in progress and will be presented.

Conclusion: We have demonstrated utility of specific FGFR analysis using well defined model systems. FGFR- profiling should be considered during the clinical work-up in order to select patients who may benefit from regimen containing specific FGFR inhibitors.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P4-06-08.

Truncated p110 ERBB2 induces mammary epithelial cell migration, invasion and orthotopic xenograft formation, and is associated with loss of phosphorylated STAT5

Truncated-ERBB2 isoforms (t-ERBB2s), resulting from receptor proteolysis or alternative translation of the ERBB2 mRNA, exist in a subset of human breast tumors. t-ERBB2s lack the receptor extracellular domain targeted by therapeutic anti-ERBB2 antibodies and antibody–drug conjugates, including trastuzumab, trastuzumab-DM1 and pertuzumab. In clinical studies, expression of t-ERBB2 in breast tumors correlates with metastasis as well as trastuzumab resistance. By using a novel immuno-microarray method, we detect a significant t-ERBB2 fraction in 18 of 31 (58%) of immunohistochemistry (IHC)3+ ERBB2+ human tumor specimens, and further show that t-ERBB2 isoforms are phosphorylated in a subset of IHC3+ samples (10 of 31, 32%). We investigated t-ERBB2 biological activity via engineered expression of full-length and truncated ERBB2 isoforms in human mammary epithelial cells (HMECs), including HMEC and MCF10A cells. Expression of p110 t-ERBB2, but not p95m (m=membrane, also 648CTF) or intracellular ERBB2s, significantly enhanced cell migration and invasion in multiple cell types. In addition, only expression of the p110 isoform led to human breast epithelial cell (HMLE) xenograft formation in vivo. Expression of t-ERBB2s did not result in hyperactivation of the phosphoinositide kinase-3/AKT or mitogen-activated protein kinase signaling pathways in these cells; rather, phosphoproteomic array profiling revealed attenuation of phosphorylated signal transducer and activator of transcription 5 (STAT5) in p110-t-ERBB2-expressing cells compared to controls. Short hairpin-mediated silencing of STAT5 phenocopied p110-t-ERBB2-driven cell migration and invasion, while expression of constitutively active STAT5 reversed these effects. Thus, we provide novel evidence that (1) expression of p110 t-ERBB2 is sufficient for full transformation of HMEC, yielding in vivo xenograft formation, and (2) truncated p110 t-ERBB2 expression is associated with decreased phosphorylation of STAT5.

P2-01-25: Truncated p110 ERBB2 (CTF611) Increases Migration and Invasion of Breast Epithelial Cells by Inhibiting STAT5b Activation

Background: Truncated ERBB2 receptors are present in a subset of human ERBB2+ amplified/overexpressing breast tumors, and are associated with trastuzumab resistance, metastasis, and poor clinical prognosis. However, whether truncated ERBB2 receptors are drivers of metastasis has not been well defined. In this study, we examined effects of full-length (p185) and truncated (p110) ERBB2 on the migration and invasion of human mammary epithelial cells, including HMLE and MCF10A cells.

Material and Methods: Recombinant p185 and p110 ERBB2 were stably expressed in human mammary epithelial cells (HMLE) and MCF10A cells via retroviral vector. Expression of comparable levels of p185 and p110 in cells was confirmed by western blot. The phosphorylation states of downstream signaling proteins including STAT5 were assayed via phosphoproteomics and Collaborative Enzyme Enhanced Reactive (CEER™) immunoassay. The effects of the p110 constructs on cell migration and invasion were investigated by transwell assays. shRNA-encoding lentivirus was used for specific silencing of STAT5b in HMLE cells, and STAT5b silencing was confirmed at the protein level using western blot.

Results and Discussion: Expression of p110 ERBB2 increased cell migration (HMLE, p = 0.04; MCF10A, p< 0.01) and invasion (HMLE, p= 0.03) when compared to expression of p185. Furthermore, expression of p110 in HMLE cells was associated with reduced phosphorylation of STAT5b. shRNA mediated silencing of STAT5b was sufficient to increase the migration (p < 0.01) and invasion of HMLE cells, phenocopying the p110 driven effects on HMLE cells. In clinical studies, loss of activated STAT5 protein correlates with breast cancer progression and is a negative predictor of survival. By analyzing publicly available gene expression datasets, we found that STAT5b mRNA expression is also significantly decreased in breast cancer compared to normal breast tissues in several studies, as well as in ERBB2 amplified vs. nonamplified samples. To our knowledge, this is the first reported perturbation of STAT signaling by truncated ERBB2 receptor, and suggests a mechanism by which truncated p110 ERBB2 (CTF611) increases migration and invasion of breast epithelial cells. This study extends the available data regarding STAT5 loss in breast cancer progression.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P2-01-25.

Rapid molecular genetic subtyping of serotype M1 group A Streptococcus strains

Serotype M1 group A Streptococcus, the most common cause of invasive disease in many case series, generally have resisted extensive molecular subtyping by standard techniques (e.g., multilocus enzyme electrophoresis, pulsed-field gel electrophoresis). We used automated sequencing of the sic gene encoding streptococcal inhibitor of complement and of a region of the chromosome with direct repeat sequences to unambiguously differentiate 30 M1 isolates recovered from 28 patients in Texas with invasive disease episodes temporally clustered and thought to represent an outbreak. Sequencing of the emm gene was less useful for M1 strain differentiation, and restriction fragment length polymorphism analysis with IS1548 or IS1562 as Southern hybridization probes did not provide epidemiologically useful subtyping information. Sequence polymorphism in the direct repeat region of the chromosome and IS1548 profiling data support the hypothesis that M1 organisms have two main evolutionary lineages marked by the presence or absence of the speA2 allele encoding streptococcal pyrogenic exotoxin A2.