BackgroundHyperactivation of the Ras signaling pathway is a driver of many cancers, and RAS pathway activation can predict response to targeted therapies. Therefore, optimal methods for measuring Ras pathway activation are critical. The main focus of our work was to develop a gene expression signature that is predictive of RAS pathway dependence.MethodsWe used the coherent expression of RAS pathway-related genes across multiple datasets to derive a RAS pathway gene expression signature and generate RAS pathway activation scores in pre-clinical cancer models and human tumors. We then related this signature to KRAS mutation status and drug response data in pre-clinical and clinical datasets.ResultsThe RAS signature score is predictive of KRAS mutation status in lung tumors and cell lines with high (> 90%) sensitivity but relatively low (50%) specificity due to samples that have apparent RAS pathway activation in the absence of a KRAS mutation. In lung and breast cancer cell line panels, the RAS pathway signature score correlates with pMEK and pERK expression, and predicts resistance to AKT inhibition and sensitivity to MEK inhibition within both KRAS mutant and KRAS wild-type groups. The RAS pathway signature is upregulated in breast cancer cell lines that have acquired resistance to AKT inhibition, and is downregulated by inhibition of MEK. In lung cancer cell lines knockdown of KRAS using siRNA demonstrates that the RAS pathway signature is a better measure of dependence on RAS compared to KRAS mutation status. In human tumors, the RAS pathway signature is elevated in ER negative breast tumors and lung adenocarcinomas, and predicts resistance to cetuximab in metastatic colorectal cancer.ConclusionsThese data demonstrate that the RAS pathway signature is superior to KRAS mutation status for the prediction of dependence on RAS signaling, can predict response to PI3K and RAS pathway inhibitors, and is likely to have the most clinical utility in lung and breast tumors.

Although we have made great progress in understanding the complex genetic alterations that underlie human cancer, it has proven difficult to identify which molecularly targeted therapeutics will benefit which patients. Drug-specific modulation of oncogenic signaling pathways in specific patient subpopulations can predict responsiveness to targeted therapy. Here, we report a pathway-based phosphoprofiling approach to identify and quantify clinically relevant, drug-specific biomarkers for phosphatidylinositol 3-kinase (PI3K) pathway inhibitors that target AKT, phosphoinositide-dependent kinase 1 (PDK1), and PI3K-mammalian target of rapamycin (mTOR). We quantified 375 nonredundant PI3K pathway-relevant phosphopeptides, all containing AKT, PDK1, or mitogen-activated protein kinase substrate recognition motifs. Of these phosphopeptides, 71 were drug-regulated, 11 of them by all three inhibitors. Drug-modulated phosphoproteins were enriched for involvement in cytoskeletal reorganization (filamin, stathmin, dynamin, PAK4, and PTPN14), vesicle transport (LARP1, VPS13D, and SLC20A1), and protein translation (S6RP and PRAS40). We then generated phosphospecific antibodies against selected, drug-regulated phosphorylation sites that would be suitable as biomarker tools for PI3K pathway inhibitors. As proof of concept, we show clinical translation feasibility for an antibody against phospho-PRAS40(Thr246). Evaluation of binding of this antibody in human cancer cell lines, a PTEN (phosphatase and tensin homolog deleted from chromosome 10)-deficient mouse prostate tumor model, and triple-negative breast tumor tissues showed that phospho-PRAS40(Thr246) positively correlates with PI3K pathway activation and predicts AKT inhibitor sensitivity. In contrast to phosphorylation of AKT(Thr308), the phospho-PRAS40(Thr246) epitope is highly stable in tissue samples and thus is ideal for immunohistochemistry. In summary, our study illustrates a rational approach for discovery of drug-specific biomarkers toward development of patient-tailored treatments.

As palliative care shifts from care of the dying to a broader focus on an integrated model where treatment is directed to any patient with a life-threatening illness, nurses working in this area will need to become familiar with common pain syndromes seen in those surviving their illness. In particular, pain syndromes in persons surviving cancer are being seen with greater frequency in the clinical setting. These include persistent pain due to surgery, chemotherapy, radiotherapy, stem cell transplant, and hormonal therapy. To illustrate the complex array of complications that can occur as a result of cancer treatment, a case is presented that describes the course experienced by one patient many years after therapy, as well as the management provided by the palliative care and hospice teams.

Malignant bowel obstruction (MBO) is a common occurrence in patients with abdominal and pelvic malignancies. MBO is a complex problem that is a result of a cascade of pathophysiological events. For many patients near the end of life, aggressive medical management of this problem is necessary because patients are not candidates for surgery. An assessment and thoughtful examination of options for intervention is important in aligning treatments with patients' goals of care. The palliative care nurse has an important and privileged role in nursing, educating and advocating for patients with MBO. This article reviews the normal and abnormal physiology of the gastrointestinal tract. Advice is provided for the assessment and management of the physical and psychological symptoms of MBO in patients near the end of life.

Protein phosphorylation plays a key role in cell signaling and pathophysiological alterations in protein kinases and phosphatases contribute to human diseases. We used stable isotope labeling by amino acids (SILAC) in cell culture combined with phospho-antibody based enrichment for quantitative mass-spectrometry-based identification of differentially phosphorylated proteins in response to small-molecule PI3K-pathway inhibition. We quantified over 500 non-redundant serine/threonine phosphopeptides (NSTPs) containing either the AKT-, MAPK-substrate, or PDK1-docking motif. Of these NSTPs, 71 phosphoproteins were modulated by inhibitors targeting either AKT, PDK1 or PI3K/mTOR and a common set of 11 were modulated by all three drugs. Bioinformatics analysis of the regulated phosphoproteins identified core components of the canonical PI3K pathway and showed enrichment in adaptor and scaffolding molecules involved in cell polarity (PAK4), cytoskeletal reorganization (Filamin, Stathmin, Dynamin) vesicle transport (LARP1, VPS13D, SLC20A1), protein translation (S6RP and PRAS40), and transcription (EIF4BP-1). These results have guided the rational selection of antibodies for biomarker and patient stratification assays and a newly developed phosphor-specific antibody against PRAS40T246 shows specificity for oncogenic PI3K-pathway activation in PTEN-deficient mouse prostate tumor tissue by immunohistochemistry. In addition, the phospho-PRAS40T246 biomarker was evaluated across a panel of 67 breast and 96 lung cancer cell lines and in triple negative human breast tumor tissue. In these datasets, phopspho-PRAS40T246 positively correlates with phospho-AKTS473, but not PTEN protein expression. As such, we have positioned PRAS40T246 as a clinically relevant biomarker for the identification of PI3K-pathway activated tumors to enable individualized cancer therapy. 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 5560.