Prognostic and predictive gene signature for adjuvant chemotherapy in resected non-small-cell lung cancer

PURPOSE

The JBR.10 trial demonstrated benefit from adjuvant cisplatin/vinorelbine (ACT) in early-stage non-small-cell lung cancer (NSCLC). We hypothesized that expression profiling may identify stage-independent subgroups who might benefit from ACT.

PATIENTS AND METHODS

Gene expression profiling was conducted on mRNA from 133 frozen JBR.10 tumor samples (62 observation [OBS], 71 ACT). The minimum gene set that was selected for the greatest separation of good and poor prognosis patient subgroups in OBS patients was identified. The prognostic value of this gene signature was tested in four independent published microarray data sets and by quantitative reverse-transcriptase polymerase chain reaction (RT-qPCR).

RESULTS

A 15-gene signature separated OBS patients into high-risk and low-risk subgroups with significantly different survival (hazard ratio [HR], 15.02; 95% CI, 5.12 to 44.04; P < .001; stage I HR, 13.31; P < .001; stage II HR, 13.47; P < .001). The prognostic effect was verified in the same 62 OBS patients where gene expression was assessed by qPCR. Furthermore, it was validated consistently in four separate microarray data sets (total 356 stage IB to II patients without adjuvant treatment) and additional JBR.10 OBS patients by qPCR (n = 19). The signature was also predictive of improved survival after ACT in JBR.10 high-risk patients (HR, 0.33; 95% CI, 0.17 to 0.63; P = .0005), but not in low-risk patients (HR, 3.67; 95% CI, 1.22 to 11.06; P = .0133; interaction P < .001). Significant interaction between risk groups and ACT was verified by qPCR.

CONCLUSION

This 15-gene expression signature is an independent prognostic marker in early-stage, completely resected NSCLC, and to our knowledge, is the first signature that has demonstrated the potential to select patients with stage IB to II NSCLC most likely to benefit from adjuvant chemotherapy with cisplatin/vinorelbine.

Abstract A20: FGFR1-amplified squamous cell lung cancers depend on FGFR1

In lung adenocarcinomas of never-smokers EGFR mutations or EML4-ALK gene fusions are frequent genomic events that both expose prime therapeutic targets. By contrast, squamous cell lung cancer (SQLC) is almost invariably associated with smoking; in this subgroup of patients, no attractive therapeutic target has so far been identified. In order to identify such a therapeutically exploitable target in SQLC, we performed high-resolution genomic analyses of over 300 lung tumor specimens. Using 6.0 Affymetrix SNP-arrays we identified high-level focal amplifications of FGFR1 in 10% of over 150 primary SQLC specimens. Importantly, FGFR1 amplification was almost exclusively restricted to SQLC of smokers and almost never observed in adenocarcinomas. We also performed high-throughput cell line screening of 82 genomically annotated lung cancer cell lines using the FGFR inhibitor PD170374 and identified the presence of focal FGFR1 -amplifications as the strongest predictor of PD170374 activity. Biochemical kinase profiling across 108 kinases suggested that PD170374 was highly selective with only one of the kinases being inhibited to a similar extend as FGFR1 itself. Treatment with PD173074 induced apoptosis and inhibited MAPK- and, to a lesser extend, PI3K signaling in cell lines with focal amplification of FGFR1. In order to validate FGFR1 as a critical target in FGFR1 -amplified cells we employed retroviral expression of the gatekeeper mutant allele of FGFR1 (V561M) and thus the PD173074-sensitive cells were rendered resistant. Additionally, lentiviral-mediated knockdown of FGFR1 in FGFR1 -amplified cell lines confirmed FGFR1 as a critical target for FGFR1 inhibition in these cells. Finally, successful treatment of mice engrafted with FGFR1 -amplified lung cancer cell lines with PD173074 confirmed its on-target activity in vivo. Overall, our work demonstrates the functional relevance of amplification of FGFR1 in lung cancer and suggests that inhibition of FGFR with targeted therapeutics might be an effective strategy in squamous cell carcinoma patients with focal amplification of FGFR1.

Citation Information: Clin Cancer Res 2010;16(14 Suppl):A20.

Surface and solution properties of anionic/nonionic surfactant mixtures of alkylbenzene sulfonate and triethyleneglycol decyl ether

The surface adsorption behavior and the solution microstructure of mixtures of the C(6) isomer of anionic surfactant sodium para-dodecyl benzene sulfonate, ABS, with nonionic surfactant monodecyl triethyleneglycol ether, C(10)E(3,) have been investigated using a combination of neutron reflectivity, NR, and small-angle neutron scattering, SANS. In solution, the mixing of C(10)E(3) and ABS results in the formation of small globular micelles over most of the composition range (100:0 to 20:80 ABS/C(10)E(3)). Planar aggregates (lamellar or unilamellar vesicles, ULV) are observed for solution compositions rich in the nonionic surfactant (>80 mol % nonionic). Prior to the transition to planar aggregates, the micelle aggregation number increases with increasing nonionic composition. The lamellar-phase region is preceded by a narrow range of composition over which mixtures of micelles and small unilamellar vesicles coexist. The variation in surface absorption behavior with solution composition shows a strong surface partitioning of the more surface-active component, C(10)E(3). This pronounced departure from ideal mixing is not readily explained by existing surfactant mixing theories. In the presence of Ca(2+) ions, a more complex evolution of solution phase behavior with solution composition is observed. The lamellar-phase region occurs over a broader range of solution compositions at the expense of the small-vesicle phase. The phase boundaries are shifted to lower nonionic compositions, and the extent to which the solution-phase diagrams are modified increases with increasing calcium ion concentration. The SANS data for the large planar aggregates are consistent with large polydisperse flexible unilamellar vesicles. In the presence of Ca(2+) ions, the surface adsorption patterns become more consistent with ideal mixing in the nonionic-rich region of the surface-phase diagram. However, in the ABS-rich regions the surface behavior is more complex because of the spontaneous formation of more complex surface microstructures (bilayers to multilayers). Both in water and in the presence of Ca(2+) ions the variations in the surface adsorption behavior and in the solution mesophase structure do not appear to be closely correlated.

Targeted next-generation sequencing of DNA regions proximal to a conserved GXGXXG signaling motif enables systematic discovery of tyrosine kinase fusions in cancer

Tyrosine kinase (TK) fusions are attractive drug targets in cancers. However, rapid identification of these lesions has been hampered by experimental limitations. Our in silico analysis of known cancer-derived TK fusions revealed that most breakpoints occur within a defined region upstream of a conserved GXGXXG kinase motif. We therefore designed a novel DNA-based targeted sequencing approach to screen systematically for fusions within the 90 human TKs; it should detect 92% of known TK fusions. We deliberately paired ‘in-solution’ DNA capture with 454 sequencing to minimize starting material requirements, take advantage of long sequence reads, and facilitate mapping of fusions. To validate this platform, we analyzed genomic DNA from thyroid cancer cells (TPC-1) and leukemia cells (KG-1) with fusions known only at the mRNA level. We readily identified for the first time the genomic fusion sequences of CCDC6-RET in TPC-1 cells and FGFR1OP2-FGFR1 in KG-1 cells. These data demonstrate the feasibility of this approach to identify TK fusions across multiple human cancers in a high-throughput, unbiased manner. This method is distinct from other similar efforts, because it focuses specifically on targets with therapeutic potential, uses only 1.5 µg of DNA, and circumvents the need for complex computational sequence analysis.

Adsorption of nonionic and mixed nonionic/cationic surfactants onto hydrophilic and hydrophobic cellulose thin films

The adsorption of the nonionic surfactant hexaethylene monododecyl ether, C(12)E(6), and the mixed nonionic/cationic surfactants C(12)E(6) and hexadecyl trimethyl ammonium bromide, C(16)TAB, onto the hydrophilic and hydrophobic surfaces of thin cellulose films, formed by Langmuir-Blodgett, L-B, deposition, have been studied by neutron reflectivity. For the surfactant mixtures, considerable nonideal mixing is observed at both hydrophobic and hydrophilic surfaces. The results demonstrate that the C(12)E(6), C(12)E(6)/C(16)TAB mixture and solvent have a greater penetration into the cellulose film upon adsorption, compared to that observed in previous studies of C(16)TAB adsorbed onto cellulose, due to the presence of the nonionic surfactant. From the range of measurements made, it is concluded that both the presence of the nonionic surfactant and the nature of the cellulose films are both contributing factors to this increased penetration and swelling of the cellulose film.

Synthesis and biological evaluation of 4-anilinoquinolines as potent inhibitors of epidermal growth factor receptor

The mutant receptor tyrosine kinase EGFR is a validated and therapeutically amenable target for genotypically selected lung cancer patients. Here we present the synthesis and biological evaluation of a series of 6- and 7-substituted 4-anilinoquinolines as potent type I inhibitors of clinically relevant mutant variants of EGFR. Quinolines 3a and 3e were found to be highly active kinase inhibitors in biochemical assays and were further investigated for their biological effect on EGFR-dependent Ba/F3 cells and non-small cell lung cancer (NSCLC) cell lines.

Abstract 2189: Efficacy of combination therapies in lung cancer

Genetically activated oncogenes induce dependency on the constitutively activated oncoprotein in cancer cells. Targeted therapeutics that shut down the oncogenic signaling, induce apoptosis and thus lead to tumor shrinkage in patients can exploit this dependency. However, efficacy of single-agent inhibition often is limited by release of negative feedback loops or incomplete suppression of its primary target at clinically relevant concentrations.

The lack of preclinical models that capture the genomic diversity of human tumors impedes the transition from preclinical drug discovery to clinical trials lies in and this diversity. We sought to overcome these limitations and therefore we established a panel of 84 non-small cell lung cancer cell lines and characterized in depth in gene copy number, gene expression and mutation space.

We applied a chemo-genomics approach in order to determine the efficacy of single-agent and combination treatment with PI3K-, MAPK- and receptor tyrosine kinase (RTK-) inhibitors in genotypically defined subsets of tumor cells. We found RTK-driven tumors to largely depend on PI3K and RAS-/ RAF-driven tumors to be addicted to the MAPK signaling pathways, respectively. However, release of negative feedback loops led to activation of the alternate pathway. Combined inhibition of PI3K- and MAPK-pathways potently suppressed release of negative feedback loops, thereby resulting in enhanced induction of apoptosis in tumor cells and tumor shrinkage in vivo. In the subset of EGFR mutated cells harboring the gatekeeper mutation T790M we found limited efficacy of single-agent treatment with irreversible EGFR inhibitors. This limited activity could be linked to decreased binding velocity to the mutant kinase. However combined treatment of T790M-mutant tumor cells with irreversible ERBB inhibitors, and PI3K/mTOR inhibitors led to induction of apoptosis. Recently we established a systematic screening pipeline for the study of combined inhibition of key nodules of oncogenic signaling pathways and preliminary results suggest a critical role of PI3K/mTOR-signaling for efficacy of combination therapies. Overall our approach builds a robust framework for the preclinical study of combination therapies and might help to direct future drug development and patient stratification in clinical trials.

Note: This abstract was not presented at the AACR 101st Annual Meeting 2010 because the presenter was unable to attend.

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 2189.

Abstract A18: A novel targeted capture and massively parallel sequencing platform for systematic discovery of tyrosine kinase fusions in cancer

Purpose: To identify systematically unknown kinase fusions in an unbiased manner from minimal amounts of tumor-derived genomic DNA.

Background: Tyrosine kinase (TK) fusion proteins drive tumorigenesis of many different cancers through deregulated kinase activity. Since cancer cells are dependent on such aberrant signaling, TK fusions are attractive drug targets, and effective therapies targeting these lesions have translated rapidly into the clinic. Unfortunately, only a limited number of TK fusions have been found, because current methods for their identification lack sufficient throughput to allow for systematic analyses of hundreds of tumors. We hypothesized that tumors contain as yet unidentified TK fusions whose discovery has been hindered by these experimental limitations.

Experimental Procedures: To overcome these challenges, we performed an in silico analysis of the protein and genomic breakpoint sequences of known cancer-derived TK fusions (n=59). All TK fusions identified to date contain an intact GXGXXG kinase motif. Fusion points at the genomic level occurred within a defined region upstream of this motif, evoking a high throughput screening strategy. We therefore applied DNA capture (Agilent SureSelect) technology to target specifically these regions where breakpoints were likely to occur. Our custom DNA capture platform included all 90 human TKs (and AKT-1, -2, -3 and BRAF), and should capture ∼92% of known TK fusions. The captured DNA was then subjected to 454 massively parallel sequencing. We chose 454 sequencing because the long read length (∼200 nts) would allow for identification of breakpoints that occurred far upstream of the GXGXXG motif. To validate this platform, we used DNA (1.5 g per sample) from thyroid cancer cells (TPC-1) and acute myeloid leukemia cells (KG-1) with known fusions at the mRNA level but unknown fusion points at the genomic level. The recovered sequences were analyzed using two independently derived novel computational algorithms designed specifically for this application.

Results: Approximately 60,000 and 100,000 captured 454 sequences were recovered from TPC-1 and KG-1 cells, respectively. TK-containing sequences were enriched ∼776 fold across both samples, indicating the efficiency of our capture method. Candidate fusion sequences were validated by PCR with breakpoint-spanning primers. Among the 15 candidate fusions identified from computational analyses of the TPC-1 sequences, only the CCDC6-RET fusion was validated by direct sequencing of the PCR products. Whereas the CCDC6-RET sequence juxtaposed intronic elements from the fusion partners, the FGFR1OP2-FGFR1 fusion sequence in KG-1 cells proved more complex. The only validated fusion sequence among the 30 candidates contained two non-contiguous portions of FGFR1. Further analysis with long-range PCR revealed that this sequence was actually part of the FGFR1OP2-FGFR1 fusion sequence, which contained inverted exonic regions between the sequences of the two fusion partners. No fusion sequences were recovered from an additional 3 control cell lines without known fusions.

Conclusions: We have developed a unique high throughput platform to map genomic fusion points involving TKs in an unbiased manner. Using this technology, we were able to identify readily the genomic sequences of 2 TK fusions mapped previously at the mRNA level. This novel method is distinct from other similar efforts, because it focuses specifically on targets with therapeutic potential, uses only 1.5 g of DNA per sample, and circumvents the need for complex computational sequence analysis. We now plan to use this screening method to search for novel TK fusions in highly annotated tumor samples.

Citation Information: Clin Cancer Res 2010;16(7 Suppl):A18

An activated ErbB3/NRG1 autocrine loop supports in vivo proliferation in ovarian cancer cells

Ovarian cancer is a leading cause of death from gynecologic malignancies. Treatment for advanced-stage disease remains limited and, to date, targeted therapies have been incompletely explored. By systematically suppressing each human tyrosine kinase in ovarian cancer cell lines by RNAi, we found that an autocrine signal-transducing loop involving NRG1 and activated ErbB3 operates in a subset of primary ovarian cancers and ovarian cancer cell lines. Perturbation of this circuit with ErbB3-directed RNAi decreased cell growth in three-dimensional culture and resulted in decreased disease progression and prolonged survival in a xenograft mouse model of ovarian cancer. Furthermore, a monoclonal ErbB3-directed antibody (MM-121) also significantly inhibited tumor growth in vivo. These findings identify ErbB3 as a potential therapeutic target in ovarian cancer.

Analysis of compound synergy in high-throughput cellular screens by population-based lifetime modeling

Despite the successful introduction of potent anti-cancer therapeutics, most of these drugs lead to only modest tumor-shrinkage or transient responses, followed by re-growth of tumors. Combining different compounds has resulted in enhanced tumor control and prolonged survival. However, methods querying the efficacy of such combinations have been hampered by limited scalability, analytical resolution, statistical feasibility, or a combination thereof. We have developed a theoretical framework modeling cellular viability as a stochastic lifetime process to determine synergistic compound combinations from high-throughput cellular screens. We apply our method to data derived from chemical perturbations of 65 cancer cell lines with two inhibitors. Our analysis revealed synergy for the combination of both compounds in subsets of cell lines. By contrast, in cell lines in which inhibition of one of both targets was sufficient to induce cell death, no synergy was detected, compatible with the topology of the oncogenically activated signaling network. In summary, we provide a tool for the measurement of synergy strength for combination perturbation experiments that might help define pathway topologies and direct clinical trials.

High-throughput molecular analysis in lung cancer: insights into biology and potential clinical applications

During the last decade, high-throughput technologies including genomic, epigenomic, transcriptomic and proteomic have been applied to further our understanding of the molecular pathogenesis of this heterogeneous disease, and to develop strategies that aim to improve the management of patients with lung cancer. Ultimately, these approaches should lead to sensitive, specific and noninvasive methods for early diagnosis, and facilitate the prediction of response to therapy and outcome, as well as the identification of potential novel therapeutic targets. Genomic studies were the first to move this field forward by providing novel insights into the molecular biology of lung cancer and by generating candidate biomarkers of disease progression. Lung carcinogenesis is driven by genetic and epigenetic alterations that cause aberrant gene function; however, the challenge remains to pinpoint the key regulatory control mechanisms and to distinguish driver from passenger alterations that may have a small but additive effect on cancer development. Epigenetic regulation by DNA methylation and histone modifications modulate chromatin structure and, in turn, either activate or silence gene expression. Proteomic approaches critically complement these molecular studies, as the phenotype of a cancer cell is determined by proteins and cannot be predicted by genomics or transcriptomics alone. The present article focuses on the technological platforms available and some proposed clinical applications. We illustrate herein how the "-omics" have revolutionised our approach to lung cancer biology and hold promise for personalised management of lung cancer.

Abstract A32: Combined inhibition of phosphoinositide-3-kinase and mitogen-activated protein kinase pathways prevents activation of feedback loops in cancer

In tumor cells, genetically activated oncogenes often induce dependency on the constitutive activity of the mutant oncoprotein. Therapeutic inhibitors exploit this dependency by abrogating the oncogenic signaling, inducing massive apoptosis and thus leading to tumor regressions in patients. The phosphoinositide-3-kinase (PI3K) and mitogen-activated protein kinase (MAPK) signaling pathways are key regulators of tumor maintenance and oncogenic transformation.

A major hurdle in the transition from preclinical drug discovery to clinical trials lies in the genomic diversity of human tumors and the lack of preclinical models that capture this diversity. Given the impact of genomic aberrations on therapeutic response, such models are necessary in order to identify genetic lesions linked with individual drug response. In order to overcome these limitations we have recently established a panel of 84 NSCLC cell lines that we have characterized in depth in gene copy number, gene expression and mutation space (Sos et al.; J Clin Invest 2009).

In this study, we interrogated whether upstream dependency encodes for a certain “downstream” dependency either in the PI3K- or the MAPK- pathway and analyzed whether such a downstream pathway dependency can be linked to certain genetic lesions. We demonstrate by systematically linking compound activity to genetic lesions in vitro and in vivo, that tumors with genetically activated receptor tyrosine kinases predominantly depend on PI3K signaling while tumors with mutations in the Ras/Raf pathway depend on MAPK signaling. However, release of negative feedback loops limited the efficacy of downstream pathway inhibition. By contrast, combined blockade of both PI3K- and MAPK-pathways was able to block the reciprocal pathway activation induced by inhibitor-mediated release of negative feedback loops and resulted in a significant increase in apoptosis. Using a systematic chemo-genomics approach, we provide a framework for PI3K and MAPK pathway activation in connection with particular genetic aberrations and provide a rationale for combined inhibition of both pathways. Our findings may impact patient stratification in clinical trials involving PI3K and MAPK inhibitors either as single agents or in combination.

Citation Information: Cancer Res 2009;69(23 Suppl):A32.

Amplification of chromosomal segment 4q12 in non-small cell lung cancer

In cancer, proto-oncogenes are often altered by genomic amplification. Here we report recurrent focal amplifications of chromosomal segment 4q12 overlapping the proto-oncogenes PDGFRA and KIT in non-small cell lung cancer (NSCLC). Single nucleotide polymorphism (SNP) array and fluorescent in situ hybridization (FISH) analysis indicate that 4q12 is amplified in 3-7% of lung adenocarcinomas and 8-10% of lung squamous cell carcinomas. In addition, we demonstrate that the NSCLC cell line NCI-H1703 exhibits focal amplification of PDGFRA and is dependent on PDGFRalpha activity for cell growth. Treatment of NCI-H1703 cells with PDGFRA-specific shRNAs or with the PDGFRalpha/KIT small molecule inhibitors imatinib or sunitinib leads to cell growth inhibition. However, these observations do not extend to NSCLC cell lines with lower-amplitude and broader gains of chromosome 4q. Together these observations implicate PDGFRA and KIT as potential oncogenes in NSCLC, but further study is needed to define the specific characteristics of those tumors that could respond to PDGFRalpha/KIT inhibitors.

High expression levels of total IGF-1R and sensitivity of NSCLC cells in vitro to an anti-IGF-1R antibody (R1507)

Background

The IGF receptor type 1 (IGF-1R) pathway is frequently deregulated in human tumors and has become a target of interest for anti-cancer therapy.

Methodology/Principal Findings

We used a panel of 22 non-small cell lung cancer (NSCLC) cell lines to investigate predictive biomarkers of response to R1507, a fully-humanized anti-IGF-1R monoclonal antibody (Ab; Roche). 5 lines were moderately sensitive (25–50% growth inhibition) to R1507 alone. While levels of phospho-IGF-1R did not correlate with drug sensitivity, 4 out of 5 sensitive lines displayed high levels of total IGF-1R versus 1 out of 17 resistant lines (p = 0.003, Fisher's Exact). Sensitive lines also harbored higher copy numbers of IGF-1R as assessed by independent SNP array analysis. Addition of erlotinib or paclitaxel to R1507 led to further growth inhibition in sensitive but not resistant lines. In one EGFR mutant lung adenocarcinoma cell line (11–18), R1507 and erlotinib co-treatment induced apoptosis, whereas treatment with either drug alone induced only cell cycle arrest. Apoptosis was mediated, in part, by the survival-related AKT pathway. Additionally, immunohistochemical (IHC) staining of total IGF-1R with an anti-total IGF-1R Ab (G11;Ventana) was performed on tissue microarrays (TMAs) containing 270 independent NSCLC tumor samples. Staining intensity was scored on a scale of 0 to 3+. 39.3% of tumors showed medium to high IGF-1R IHC staining (scores of 2+ or 3+, respectively), while 16.7% had scores of 3+.

Conclusions/Significance

In NSCLC cell lines, high levels of total IGF-1R are associated with moderate sensitivity to R1507. These results suggest a possible enrichment strategy for clinical trials with anti-IGF-1R therapy.

Repeated Clonal Relapses in Classical Hodgkin's Lymphoma and the Occurrence of a Clonally Unrelated Diffuse Large B Cell Non-Hodgkin Lymphoma in the Same Patient

Classical Hodgkin's lymphoma (cHL) and B-cell Non-Hodgkin Lymphoma (B-NHL) occasionally occur in the same patient. However, molecular studies that aim at determining the clonal relationship between both lymphomas are rare. In most instances, the lymphoma components appear to be derived from the same germinal center (GC) B cell precursor. We describe the molecular monitoring of repeated clonal relapses in a patient with cHL in whom diffuse large B cell NHL (DLBCL) developed concurrently. Intriguingly, both lymphomas were clonally unrelated. Thus, the derivation from a shared precursor likely is not a general rule in cHL and DLBCL arising in the same patient.

Predicting drug susceptibility of non-small cell lung cancers based on genetic lesions

Somatic genetic alterations in cancers have been linked with response to targeted therapeutics by creation of specific dependency on activated oncogenic signaling pathways. However, no tools currently exist to systematically connect such genetic lesions to therapeutic vulnerability. We have therefore developed a genomics approach to identify lesions associated with therapeutically relevant oncogene dependency. Using integrated genomic profiling, we have demonstrated that the genomes of a large panel of human non-small cell lung cancer (NSCLC) cell lines are highly representative of those of primary NSCLC tumors. Using cell-based compound screening coupled with diverse computational approaches to integrate orthogonal genomic and biochemical data sets, we identified molecular and genomic predictors of therapeutic response to clinically relevant compounds. Using this approach, we showed that v-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog (KRAS) mutations confer enhanced Hsp90 dependency and validated this finding in mice with KRAS-driven lung adenocarcinoma, as these mice exhibited dramatic tumor regression when treated with an Hsp90 inhibitor. In addition, we found that cells with copy number enhancement of v-abl Abelson murine leukemia viral oncogene homolog 2 (ABL2) and ephrin receptor kinase and v-src sarcoma (Schmidt-Ruppin A-2) viral oncogene homolog (avian) (SRC) kinase family genes were exquisitely sensitive to treatment with the SRC/ABL inhibitor dasatinib, both in vitro and when it xenografted into mice. Thus, genomically annotated cell-line collections may help translate cancer genomics information into clinical practice by defining critical pathway dependencies amenable to therapeutic inhibition.

Transition from vesicles to small nanometer scaled vesicles, arising from the manipulation of curvature in dialkyl chain cationic/nonionic surfactant mixed aggregates by the addition of straight chain alkanols

The addition of straight chain alkanols to the dialkyl chain cationic/nonionic surfactant mixtures of dihexadecyl dimethyl ammonium bromide, DHDAB, and dodecaethylene monododecyl ether, C(12)E(12), has been used to manipulate the mean curvature of the self-assembled aggregates. This induces some significant structural changes and notably the formation of small unilamellar vesicles, nanometer scaled vesicles, L(sv). These structural changes have been measured and quantified using small angle neutron scattering, SANS. At a solution concentration of 25 mM, the DHDAB/C(12)E(12) mixtures have a structural evolution, from C(12)E(12) rich to DHDAB rich solution compositions, of small globular micelles, L(1), to micellar/vesicle coexistence, L(1)/L(v) or L(v)/L(1), to vesicle structures, L(v), bilamellar or multilamellar vesicles, blv or mlv. The impact of the addition of straight chain alkanols (in the range octanol to hexadecanol) depends upon the alkyl chain length and the amount of alcohol added. Furthermore, the effect of the addition of octanol and decanol appears to be distinctly different from that of the larger straight chain alkanols of dodecanol and hexadecanol. For the addition of octanol and decanol to C(12)E(12) rich DHDAB/C(12)E(12) mixtures, the alcohol is solubilized into the micellar core, and as the amount of alcohol added increases, significant micellar growth is ultimately observed. However, notably at intermediate DHDAB/C(12)E(12) solution compositions, in the region of L(1)/L(v) or L(v)/L(1) coexistance in the absence of alcohol, the addition of octanol or decanol promotes the formation of relatively small unilamellar vesicles, L(sv), nanometer sized vesicles, with a mean diameter in the range 70-140 A. For solutions that are rich in DHDAB, the addition of octanol or decanol results in a transition to L(v)/L(sv) coexistence and ultimately to L(v) formation. In contrast, the addition of the larger straight chain length alkanols, dodecanol or hexadecanol, to DHDAB/C(12)E(12) mixtures results in a somewhat different behavior. In this case, the addition of dodecanol or hexadecanol results in the transition from L(1) to L(1)/L(v) to L(v) occurring for solutions less rich in DHDAB than is observed in the absence of alcohol. That is, there is an enhanced tendency toward the formation of structures with a lower net curvature, either blv or mlv. Notably, for these mixtures, the small unilamellar nanometer scaled vesicle phase, L(sv), is absent.

Interplay between the surface adsorption and solution-phase behavior in dialkyl chain cationic-nonionic surfactant mixtures

Neutron reflectivity, NR, and surface tension have been used to study the adsorption at the air-solution interface of mixtures of the dialkyl chain cationic surfactant dihexadecyl dimethyl ammonium bromide (DHDAB) and the nonionic surfactants monododecyl triethylene glycol (C12E3), monododecyl hexaethylene glycol (C12E6), and monododecyl dodecaethylene glycol (C12E12). The adsorption behavior of the surfactant mixtures with solution composition shows a marked departure from ideal mixing that is not consistent with current theories of nonideal mixing. For all three binary surfactant mixtures there is a critical composition below which the surface is totally dominated by the cationic surfactant. The onset of nonionic surfactant adsorption (expressed as a mole fraction of the nonionic surfactant) increases in composition as the ethylene oxide chain length of the nonionic cosurfactant increases from E3 to E12. Furthermore, the variation in the adsorption is strongly correlated with the variation in the phase behavior of the solution that is in equilibrium with the surface. The adsorbed amounts of DHDAB and the nonionic cosurfactants have been used to estimate the monomer concentration that is in equilibrium with the surface and are shown to be in reasonable qualitative agreement with the variation in the mixed critical aggregation concentration (cac).

Interaction of a cationic gemini surfactant with DNA and with sodium poly(styrene sulphonate) at the air/water interface: a neutron reflectometry study

The interactions between a dicationic gemini surfactant with a six-hydrocarbon spacer (1,2-bis(dodecyldimethyl-ammonio)hexane dibromide, C12C6C12Br2) and anionic polyelectrolyte DNA or sodium (polystyrene sulfonate) (NaPSS) at the air/solution interface have been studied and compared using neutron reflectometry together with surface tension. In the presence of the dichained cationic gemini surfactant, DNA and NaPSS display very different adsorption behaviors. The DNA/gemini mixtures show adsorption behavior very similar to that of DNA/C12TAB mixtures, with enhanced surfactant adsorption at low concentrations and thick structured layers at higher concentrations. However, for the NaPSS/gemini mixtures the amount of gemini at the surface is reduced relative to that in the absence of NaPSS at concentrations below the cmc. These differences in adsorption behavior are attributed to differences in the molecular structure and flexibility of the two polyanions. NaPSS is relatively hydrophobic and flexible enough to form bulk-phase polymer-micelle complexes with the gemini surfactant at low surfactant concentrations, whereas the adsorption of surface complexes is much less favorable because the dications on the gemini would require adjacent bulky pendant charges on the NaPSS to be oriented toward the surface. This would force the NaPSS to bend significantly whereas it is more favorable for the NaPSS to adopt an extended conformation at the surface. Thus, surfactant is actually removed from the surface to form bulk-phase complexes. In contrast with NaPSS, DNA has a far more rigid structure, and the charges on the backbone are at fixed intervals, factors that make the formation of surface DNA-monomer complexes much more favorable than bulk-phase DNA-micelle complexes. Finally, a short-chain sample of NaPSS consisting of only five to six segments adsorbs very strongly at the surface with the gemini to form more extensive layered structures than have previously been observed, consisting of approximately five sublayers.

Nature of amine-surfactant interactions at the air-solution interface

The surface tension and adsorption behavior of polymer/surfactant mixtures of polyethyleneimine (PEI)/sodium dodecyl sulfate (SDS) is strongly dependent on pH. At both low and high pH, a strong PEI/SDS interaction gives rise to surface polymer/surfactant complex formation that results in significantly enhanced SDS adsorption at very low SDS concentrations and in multilayer formation at the interface. At low pH, this strong PEI/SDS interaction is dominated by the electrostatic attraction between the two oppositely charged species. However, at high pH the PEI is essentially neutral, and the origin of the "hydrophobic" interaction, or interaction of nonelectrostatic origin, is less clear. To investigate the origins of this interaction further, we have used neutron reflectivity and surface tension to study the pH dependence of the surface adsorption of different anionic surfactants-SDS, lithium dodecyl sulfate (LiDS), and sodium dodecyl benzene sulfonate (LAS)--in the presence of a range of small amine molecules (from ethylenediamine to pentaethylenehexamine). Analogous to that observed in PEI/SDS mixtures, the presence of amine molecules induces a strong enhancement in the surfactant adsorption at both low and high pH, which can result in extreme cases in multilayer formation at the interface. At high pH, the adsorption is highly dependent upon the amine molecular weight and is equivalent to that observed at low pH by the time the molecular weight of the amine has increased to that of pentaethylenehexamine. We attribute this nonelectrostatic interaction observed at high pH to the combined effect of a dipole-dipole interaction between the sulfate (or sulfonate) headgroup and the amine nitrogens and a cooperative hydrophobic interaction between the chains of the attached surfactants. At high pH and when there are at least six amine groups present, this effect appears to be equivalent in strength to the electrostatic attraction that dominates at low pH. These results are significant in the context of understanding the unusual nature of the PEI/surfactant interaction and of using small molecular weight additives rather than much larger molecular weight polymers to manipulate adsorption properties.

Structure of partially fluorinated surfactant monolayers at the air-water interface

Partially fluorinated cationic surfactants of the form C(n)F(2n+1)C(m)H(2m)N(CH3)Br have been prepared, and their behavior at the air-water interface has been studied using surface tension measurements and neutron reflectometry. The degree of fluorination has been varied while keeping the overall chain lengths similar. The results are compared with those previously obtained for C16H33N(CH3)Br (C16TAB). The structural studies show a decrease in molecular orientation with increasing fluorination. The mean tilt away from the surface normal varies from 55 degrees for C16TAB to 25 degrees for C8F17C6H12N(CH3)Br. The interfacial layer roughness is observed to be lower than that expected for a pure fluorocarbon surfactant.

PTEN loss contributes to erlotinib resistance in EGFR-mutant lung cancer by activation of Akt and EGFR

Clinical resistance to epidermal growth factor receptor (EGFR) inhibition in lung cancer has been linked to the emergence of the EGFR T790M resistance mutation or amplification of MET. Additional mechanisms contributing to EGFR inhibitor resistance remain elusive. By applying combined analyses of gene expression, copy number, and biochemical analyses of EGFR inhibitor responsiveness, we identified homozygous loss of PTEN to segregate EGFR-dependent and EGFR-independent cells. We show that in EGFR-dependent cells, PTEN loss partially uncouples mutant EGFR from downstream signaling and activates EGFR, thereby contributing to erlotinib resistance. The clinical relevance of our findings is supported by the observation of PTEN loss in 1 out of 24 primary EGFR-mutant non-small cell lung cancer (NSCLC) tumors. These results suggest a novel resistance mechanism in EGFR-mutant NSCLC involving PTEN loss.

Monomer-aggregate exchange rates in dialkyl chain cationic-nonionic surfactant mixtures

The monomer-aggregate exchange rate in self-assembled dialkyl chain cationic-nonionic mixed surfactant aggregates has been studied using small-angle neutron scattering, SANS, and a stopped-flow apparatus. SANS was used to follow the evolution of the structure with time of an equimolar mixture of the dialkyl chain cationic surfactant dihexadecyl dimethyl ammonium bromide, DHDAB, in D2O with the nonionic surfactant dodecaethylene monododecyl ether, C12E12, in D2O at a solution concentration of 1.5 mM. With increasing time, the bilamellar vesicle structure, blv, of DHDAB and the globular micellar structure, L1, of C12E12 evolved to a lamellar (Lbeta or Lalpha)/micellar (L1) coexistence. Measurements were made for the isotopically labeled combinations of hydrogeneous DHDAB (h-DHDAB) and alkyl chain deuterium-labeled C12E12 (d-C12E12) in D2O such that the lamellar contribution is the predominantly visible contribution to the scattering. From the variation (decrease) in the scattering intensity with time (measured at a scattering vector of approximately 0.014 angstroms(-1)), a characteristic time was measured at 32 degrees C (T < Lbeta/Lalpha transition temperature) and at 46 degrees C (T > Lbeta/Lalpha). The characteristic time was approximately 130 min and a few seconds respectively, indicating a dramatic change in the monomer/aggregate exchange rate between the solid-like Lbeta and fluid-like Lalpha phases. The characteristic time of approximately 130 min in the Lbeta phase is indicative of a slow monomer-aggregate exchange rate and is consistent with the slow kinetics of adsorption of DHDAB and DHDAB/nonionic surfactant mixtures observed at the air-water interface. This slow adsorption kinetics was assumed to arise from near-surface depletion effects associated with slow monomer/aggregate exchange rates, and these results support and reinforce that hypothesis.