BackgroundSomatic mutations in the kinase domain of the epidermal growth factor receptor tyrosine kinase gene EGFR are common in lung adenocarcinoma. The presence of mutations correlates with tumor sensitivity to the EGFR inhibitors erlotinib and gefitinib, but the transforming potential of specific mutations and their relationship to drug sensitivity have not been described.Methods and FindingsHere, we demonstrate that EGFR active site mutants are oncogenic. Mutant EGFR can transform both fibroblasts and lung epithelial cells in the absence of exogenous epidermal growth factor, as evidenced by anchorage-independent growth, focus formation, and tumor formation in immunocompromised mice. Transformation is associated with constitutive autophosphorylation of EGFR, Shc phosphorylation, and STAT pathway activation. Whereas transformation by most EGFR mutants confers on cells sensitivity to erlotinib and gefitinib, transformation by an exon 20 insertion makes cells resistant to these inhibitors but more sensitive to the irreversible inhibitor CL-387,785.ConclusionOncogenic transformation of cells by different EGFR mutants causes differential sensitivity to gefitinib and erlotinib. Treatment of lung cancers harboring EGFR exon 20 insertions may therefore require the development of alternative kinase inhibition strategies.

Oncogenic activation of tyrosine kinases is a common mechanism of carcinogenesis and, given the druggable nature of these enzymes, an attractive target for anticancer therapy. Here, we show that somatic mutations of the fibroblast growth factor receptor 2 (FGFR2) tyrosine kinase gene, FGFR2, are present in 12% of endometrial carcinomas, with additional instances found in lung squamous cell carcinoma and cervical carcinoma. These FGFR2 mutations, many of which are identical to mutations associated with congenital craniofacial developmental disorders, are constitutively activated and oncogenic when ectopically expressed in NIH 3T3 cells. Inhibition of FGFR2 kinase activity in endometrial carcinoma cell lines bearing such FGFR2 mutations inhibits transformation and survival, implicating FGFR2 as a novel therapeutic target in endometrial carcinoma.endometrial cancer ͉ fibroblast growth factor receptor 2 ͉ oncogene ͉ targeted therapy ͉ tyrosine kinase T yrosine kinases play a major role in transduction of proliferative signals and can become oncogenic when deregulated by somatic mutation (1). Somatically altered tyrosine kinases have proven to be tractable therapeutic targets in several tumor types; examples of successfully targeted tyrosine kinases include ABL1 in chronic myeloid leukemia (2), KIT in gastrointestinal stromal tumors (3), ERBB2 in breast cancer (4), and EGFR in non-small-cell lung cancer (5-7). The tyrosine kinase family has not been exhaustively studied in human cancer, and it is likely that additional tyrosine kinase therapeutic targets remain to be discovered.The fibroblast growth factor receptor (FGFR) tyrosine kinase family, which is comprised of four kinases that differentially respond to 18 FGF ligands (8, 9), has long been implicated in cancer. Translocations involving FGFR3, and activating somatic mutations in FGFR3, have been identified in multiple myeloma patients (10, 11), and translocations of FGFR1 have been found in patients with 8p11 myeloproliferative syndrome (12). Isolated cases of a missense mutation of FGFR4 in a lung adenocarcinoma patient and missense mutations of FGFR2 in a lung squamous cell carcinoma patient and gastric cancer patient have also been reported (13,14). In addition to these documented examples of somatic mutation of FGFR family members in cancer, a germ-line polymorphism in the second intron of FGFR2 was found to be associated with breast cancer in genomewide association studies (15,16).FGFR1-FGFR3 are characterized by alternative splicing of the mRNA encoding the third Ig-like repeat in the extracellular ligand-binding domain. This differential splicing determines ligand specificity such that isoforms expressed primarily in epithelial cells (IIIb) preferentially bind FGF ligands expressed by mesenchymal cells, and isoforms expressed primarily in mesenchymal cells (IIIc) preferentially bind FGF ligands expressed by epithelial cells (17)(18)(19). Alteration of this restricted expression pattern can lead to oncogenic transformation (20). Mutations in FGFR2 and FGF...

We assessed somatic alleles of six receptor tyrosine kinase genes mutated in lung adenocarcinoma for oncogenic activity. Five of these genes failed to score in transformation assays; however, novel recurring extracellular domain mutations of the receptor tyrosine kinase gene ERBB2 were potently oncogenic. These ERBB2 extracellular domain mutants were activated by two distinct mechanisms, characterized by elevated C-terminal tail phosphorylation or by covalent dimerization mediated by intermolecular disulfide bond formation. These distinct mechanisms of receptor activation converged upon tyrosine phosphorylation of cellular proteins, impacting cell motility. Survival of Ba/F3 cells transformed to IL-3 independence by the ERBB2 extracellular domain mutants was abrogated by treatment with small-molecule inhibitors of ERBB2, raising the possibility that patients harboring such mutations could benefit from ERBB2-directed therapy.HER2 | breast cancer | bladder cancer L ung cancer is the leading cause of cancer death, accounting for over 150,000 deaths annually in the United States alone (1). Current treatment options are thus inadequate for the majority of patients and additional therapies are needed. Mutationally activated oncogenes that promote tumorigenesis represent potential drug targets due to frequent dependency of tumor cells on such oncogenes (2, 3), and somatically altered receptor tyrosine kinases in particular have been successfully exploited as therapeutic targets in several cancers.The prototypical therapy targeted to a somatically activated tyrosine kinase oncogene is imatinib mesylate, which targets the BCR-ABL fusion protein in chronic myelogenous leukemia (4). Targeted therapies developed for lung cancer include gefitinib and erlotinib, small-molecule inhibitors of mutationally activated EGFR in lung adenocarcinoma (5-8), and crizotinib, a smallmolecule inhibitor of the EML4-ALK translocation product in lung adenocarcinoma (9). Trastuzumab, a monoclonal antibody inhibitor targeting ERBB2, and the small-molecule EGFR/ ERBB2 inhibitor lapatinib are effective in ERBB2-amplified patients with breast cancer (10, 11).The advent of next-generation sequencing technologies has enabled compilation of large somatic mutation datasets from cancer sequencing studies. Statistical methods that examine differences in gene mutation frequency can reveal evidence of positive selection; however, demonstration of the contribution of a mutated gene to tumorigenesis additionally requires functional validation. To identify new lung cancer oncogenes, we systematically assessed somatic alleles of significantly mutated receptor tyrosine kinase genes reported in patients with lung adenocarcinoma (12) for activity in cellular transformation assays.Although most receptor tyrosine kinase mutations tested failed to score, novel extracellular domain mutations of ERBB2 were oncogenic. Our results indicate a unique therapeutic opportunity for patients with lung and breast cancer who harbor extracellular domain mutations of ERBB2. Resul...

Reversible epidermal growth factor receptor (EGFR) inhibitors are the first class of small molecules to improve progression-free survival of patients with EGFR-mutated lung cancers. Second-generation EGFR inhibitors introduced to overcome acquired resistance by the T790M resistance mutation of EGFR have thus far shown limited clinical activity in patients with T790M-mutant tumors. In this study, we systematically analyzed the determinants of the activity and selectivity of the second-generation EGFR inhibitors. A focused library of irreversible as well as structurally corresponding reversible EGFR-inhibitors was synthesized for chemogenomic profiling involving over 79 genetically defined NSCLC and 19 EGFR-dependent cell lines. Overall, our results show that the growth-inhibitory potency of all irreversible inhibitors against the EGFR

Targeted cancer therapies impede cancer cell growth by inhibiting the function of activated oncogene products. Patients with non-small cell lung cancer and somatic mutations of EGFR can have a dramatic response to treatment with erlotinib and gefitinib; different somatic mutations are associated with different times to progression and survival. In this study, the relative and absolute potencies of two distinct EGFR tyrosine kinase inhibitors, erlotinib and an investigational irreversible inhibitor, HKI-272, were found to vary significantly in a panel of Ba/F3 cells transformed by representative EGFR somatic mutations. HKI-272 more potently inhibited the primary exon 20 insertion mutants, the secondary erlotinib-resistance mutants including T790M and many erlotinib-sensitive mutants including L858R. In contrast, erlotinib is a more potent inhibitor of the major exon 19 deletion mutants than is HKI-272. Analyses of EGFR autophosphorylation patterns confirmed the mutation-specific variation in relative potency of these tyrosine kinase inhibitors. Our finding that distinct EGFR inhibitors are more effective in vitro for different mutant forms of the protein suggests that tyrosine kinase inhibitor treatment could be tailored to specific EGFR mutations. More broadly, these results imply that the development and deployment of targeted therapies should focus on inhibition of specific cancer-causing mutations, not only on the mutated target.

The complete sequencing of the human genome and the development of molecularly targeted cancer therapy have promoted efforts to identify systematically the genetic alterations in human cancer. By high-throughput sequencing of tyrosine kinase genes in human non-small-cell lung cancer, we identified somatic mutations in the kinase domain of the epidermal growth factor receptor tyrosine kinase gene (EGFR) that are correlated with clinical response to EGFR tyrosine kinase inhibitors (TKIs). We have shown that these mutant forms of EGFR induce oncogenic transformation in different cellular systems. Cells whose growth depends on EGFR with mutations in exons 19 and 21 are sensitive to EGFR-TKIs, whereas cells expressing insertion mutations in exon 20 or the T790M point mutant, found in tumor biopsies from patients that relapsed after an initial response to EGFR-TKIs, are resistant. Furthermore, by applying a novel, massively parallel sequencing technology, we have shown that clinically relevant oncogene mutations can be detected in clinical specimens with very low tumor content, thereby enabling optimal patient selection for mutation-directed therapy. In summary, by applying high-throughput genomic resequencing, we have identified a novel therapeutic target, mutant EGFR, in lung cancer and evaluated its role in predicting response to targeted therapy.

We investigated the major determinant of hyperphosphatemia incidence among patients receiving peritoneal dialysis. Seventy-six patients aged 25-55 years who had received peritoneal dialysis for more than 3 months were recruited. The patients were divided into three groups according to their serum phosphorus levels (Group 1, ≥ 6 mg/dL; Group 2, 5.9-4.8 mg/dL; and Group 3, <4.8 mg/dL). Renal dietitians interviewed the patients to determine their phosphate intake and adherence to phosphate binder therapy. No statistical differences in demographics or phosphate intake were identified among the groups. However, adherence to phosphate binders was greater in Group 3 than in Groups 1 and 2 (96.3% vs. 21.4% and 52.4%, respectively; P < 0.001). Multivariate analysis showed that adherence to phosphate binder therapy was the only significant contributor to serum phosphorus levels (P= 0.0001). Adherence to diet was better than adherence to phosphate binder therapy among patients receiving peritoneal dialysis, and the latter determined the incidence of hyperphosphatemia.

A study on poly tetrafluoroethylene (PTFE) reinforced with two nano-sized silica is described in this article. This includes the discussion of thermal, mechanical, and dielectric properties of the PTFE-silica composites. In this study, it is found that the composites filled with 2wt% nano-sized silica (20 nm) and 33wt% micron-sized silica (5 mm) have the best modulus. Furthermore, the Z-direction coefficients of thermal expansion (CTEz) decrease with the increasing concentration of nano-sized silica in the composites. The higher the content of nano-sized silica added in the PTFE results in the porous morphology, and lowers the dielectric constant.