Inducible expression of TGFβ, snail and Zeb1 recapitulates EMT in vitro and in vivo in a NSCLC model

The progression of cancer from non-metastatic to metastatic is the critical transition in the course of the disease. The epithelial to mesenchymal transition (EMT) is a mechanism by which tumor cells acquire characteristics that improve metastatic efficiency. Targeting EMT processes in patients is therefore a potential strategy to block the transition to metastatic cancer and improve patient outcome. To develop models of EMT applicable to in vitro and in vivo settings, we engineered NCI-H358 non-small cell lung carcinoma cells to inducibly express three well-established drivers of EMT: activated transforming growth factor β (aTGFβ), Snail or Zeb1. We characterized the morphological, molecular and phenotypic changes induced by each of the drivers and compared the different end-states of EMT between the models. Both in vitro and in vivo, induction of the transgenes Snail and Zeb1 resulted in downregulation of epithelial markers and upregulation of mesenchymal markers, and reduced the ability of the cells to proliferate. Induced autocrine expression of aTGFβ caused marker and phenotypic changes consistent with EMT, a modest effect on growth rate, and a shift to a more invasive phenotype. In vivo, this manifested as tumor cell infiltration of the surrounding mouse stromal tissue. Overall, Snail and Zeb1 were sufficient to induce EMT in the cells, but aTGFβ induced a more complex EMT, in which changes in extracellular matrix remodeling components were pronounced.

Implementation of neuro-oncology service reconfiguration in accordance with NICE guidance provides enhanced clinical care for patients with glioblastoma multiforme

Background:

Brain tumours account for <2% of all primary neoplasms but are responsible for 7% of the years of life lost from cancer before age 70 years. The latest survival trends for patients with CNS malignancies have remained largely static. The objective of this study was to evaluate the change in practice as a result of implementing the Improving Outcomes Guidance from the UK National Institute for Health and Clinical Excellence (NICE).

Methods:

Patients were identified from the local cancer registry and hospital databases. We compared time from diagnosis to treatment, proportion of patients discussed at multidisciplinary team (MDT) meetings, treatment received, length of inpatient stay and survival. Inpatient and imaging costs were also estimated.

Results:

Service reconfiguration and implementation of NICE guidance resulted in significantly more patients being discussed by the MDT—increased from 66 to 87%, reduced emergency admission in favour of elective surgery, reduced median hospital stay from 8 to 4.5 days, increased use of post-operative MRI from 17 to 91% facilitating early discharge and treatment planning, and reduced cost of inpatient stay from £2096 in 2006 to £1316 in 2009. Patients treated with optimal surgery followed by radiotherapy with concomitant and adjuvant temozolomide achieved outcomes comparable to those reported in clinical trials: median overall survival 18 months (2-year survival 35%).

Conclusions:

Advancing the management of neuro-oncology patients by moving from an emergency-based system of patient referral and management to a more planned elective outpatient-based pattern of care improves patient experience and has the potential to deliver better outcomes and research opportunities.

Abstract 5063: Preclinical evaluation of an EMT multi-gene biomarker index for predicting response to inhibitors of EGFR and IGF1R

In oncology, the goal of personalized medicine is to improve patient outcome by tailoring therapy to the biochemical signaling within the individual's tumor. This requires identifying effective predictors of response that can be measured in biopsy material. High expression of the epithelial marker E-cadherin is associated with increased sensitivity in cultured cells and an improved survival benefit in response to erlotinib in patients. Downregulation of E-cadherin is a critical event in epithelial to mesenchymal transition (EMT) and is associated with decreased sensitivity to erlotinib. In order to determine if a more complete characterization of the EMT state would better predict sensitivity to erlotinib as well as other epithelial-targeting drugs, we developed an 88-gene signature that can be used to calculate a numerical index value which represents the EMT state of cells or tumors. In a panel of human tumor cell lines, the EMT index predicted erlotinib sensitivity correctly in 21 out of 24 lines. The index also predicted sensitivity to the IGF1R inhibitor OSI-906. While the EMT index marginally improved sensitivity prediction in vitro compared to E-cadherin, the numerical index allowed for a comparison of relative EMT states that was not possible with E-cadherin alone. Using a microarray database of human tumor sections, we computed EMT index values across 8 solid tumor types in order to compare their relative EMT states. Breast and lung tumors had a fairly even distribution between epithelial and mesenchymal tumors, while colon tumors were more epithelial, and kidney tumors were more mesenchymal. When comparing EMT index values to E-cadherin mRNA levels, some tumor types showed good agreement between E-cadherin and the EMT index (colon, kidney, lung) while others showed less agreement (breast, pancreas).

We next compared our EMT signature to other published signatures of EMT and EGFR inhibitor response. Interestingly, most signatures were equally predictive of erlotinib sensitivity in vitro, even though less than 20% of the genes overlaped between any two signatures. We also analyzed signatures developed for individual characteristics of EMT such as invasion or stem cells. These did not correlate with erlotinib sensitivity, suggesting the protection from current therapeutics is not controlled solely by these specific aspects of EMT.

Finally, we characterized sub-types of lung cancer for EMT state to determine if the EMT classification might correlate with established response rates to erlotinib. Adenocarcinomas, which tend to respond well, had more epithelial index values while squamous cell carcinomas, which tend to be less sensitive, had more mesenchymal values. This suggests that more epithelial index values might predict for erlotinib response in patients, potentially providing clinicians with a tool to more effectively treat patients based on the EMT status of their tumors.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 5063. doi:10.1158/1538-7445.AM2011-5063

Abstract 3370: The role of epithelial to mesenchymal transition (EMT) in resistance to Erlotinib in EGFR mutant NSCLC cell line models

The EGFR kinase inhibitor erlotinib is approved as a maintenance therapy in 1st line NSCLC as well as for treatment of 2nd/3rd line NSCLC and in combination with Gemcitabine for pancreatic cancer. It has been observed that the most pronounced responses to EGFR tyrosine kinase inhibitors (TKI's) were observed in patients whose tumors expressed a mutated form of the EGFR kinase. These mutations mapped to the kinase domain of the receptor and functionally have been shown to render tumors and cells lines onco-addicted to EGFR signaling. Although patients expressing a mutated EGFR show a dramatic initial response to EGFR TKI's, ∼50% of these patients will progress while on therapy after 1-2 years. The mechanisms that underlie this acquired resistance to EGFR TKI therapy have been intensively studied and include but are not limited to the presence of a second mutation, T790M, or increased HGF-MET signaling.

Previously, the role of epithelial to mesenchymal transition (EMT) in resistance to EGFR kinase inhibitors has been described in the context of wild type EGFR. EMT. We were therefore interested in understanding whether EMT could play a role in resistance to EGFR TKIs in the context of an EGFR mutation. Here we show that a panel of NSCLC cell lines, expressing mutant EGFR, can undergo an EMT in response to TGFβ treatment. The cell lines take on a scattered and spindle-like morphology and also down regulate the expression of E-cadherin and up regulate expression of vimentin, classic protein markers of an EMT. Importantly we show that after undergoing EMT, the EGFR mutant line HCC827 has reduced sensitivity to erlotnib treatment which is regained after reversal of the EMT. To further explore whether EMT could play a role in acquired resistance to erlotinib, we generated in vitro cell line models that were resistant to EGFR inhibition through continued culturing in the presence of erlotinib over a 6 month period. Resistant clones generated from parental HCC4006 cells acquired a more scattered and spindle-like morphology consistent with an EMT. These clones had down-regulated E-cadherin and ErbB3 expression and upregulated vimentin, fibronectin and Zeb1 expression and also showed a gene expression pattern consistent with having undergone an EMT. In addition, the resistant H4006 clones were more migratory and invasive than their parental counterpart. Finally we show that the resistant clones are enriched for stem cell markers and have enhanced signaling through the Src family kinases and the JAK-STAT pathway suggesting a mechanistic rationale for their reduced sensitivity to EGFR inhibitors.

Taken together. these data indicate that NSCLC cell lines that express a mutant version of EGFR are able to undergo an EMT which can influence the efficacy of EGFR TKIs, suggesting that this may be an additional mechanism underlying the acquired resistance of NSCLC patients to EGFR therapy in the clinic.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 3370. doi:10.1158/1538-7445.AM2011-3370

Abstract 3385: A systems view of epithelial – mesenchymal transition signaling states

Epithelial – mesenchymal transition (EMT) is an important contributor to the invasion and metastasis of epithelial-derived cancers. While considerable effort has focused in the regulators involved in the transition process, we have focused on consequences of EMT to prosurvival signaling. Changes in distinct metastable and ‘epigentically-fixed’ EMT states were measured by correlation of protein, phosphoprotein, phosphopeptide and RNA transcript abundance. The assembly of 1167 modulated components into functional systems or machines simplified biological understanding and increased prediction confidence highlighting four functional groups: cell adhesion and migration, metabolism, transcription nodes and proliferation/survival networks. A coordinate metabolic reduction in a cluster of 17 free-radical stress pathway components was observed and correlated with reduced glycolytic and increased oxidative phosphorylation enzyme capacity, consistent with reduced cell cycling and reduced need for macromolecular biosynthesis in the mesenchymal state. An attenuation of EGFR autophosphorylation and a switch from autocrine to paracrine-competent EGFR signaling was implicated in the enablement of tumor cell chemotaxis. A similar attenuation of IGF1R, MET and RON signaling with EMT was observed. In contrast, EMT increased prosurvival autocrine IL11/IL6-JAK2-STAT signaling, autocrine fibronectin-integrin α5β1 activation, autocrine Axl/Tyro3/PDGFR/FGFR RTK signaling and autocrine TGFβR signaling. A relatively uniform loss of polarity and cell-cell junction linkages to actin cytoskeleton and intermediate filaments was measured at a systems level. A more heterogeneous gain of ECM remodeling and associated with invasion and migration was observed. Correlation to stem cell, EMT, invasion and metastasis datasets revealed the greatest similarity with normal and cancerous breast stem cell populations, CD49fhi/EpCAM-/lo and CD44hi/CD24lo respectively.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 3385. doi:10.1158/1538-7445.AM2011-3385

Abstract LB-388: Combination treatment of a dual IGF-1R/IR kinase inhibitor, OSI-906, with EGFR inhibitor erlotinib in models of non-small cell lung cancer with an EGFR activating mutation

Erlotinib is a tyrosine kinase inhibitor of EGFR approved for use in non-small cell lung cancer (NSCLC) and pancreatic cancer in combination with Gemcitabine. Within the context of NSCLC it has been observed that patients harboring an activating mutation within the kinase domain of EGFR demonstrate a high response to treatment. However, their disease often progresses within 1 year. OSI-906 targets IGF-1R and IR receptor tyrosine kinases and has shown combination efficacy with erlotinib in preclinical models of NSCLC with wild type EGFR. Here we report preclinical data suggesting that the combination of erlotinib and OSI-906 is more efficacious in NSCLC models expressing an EGFR mutation than either single agent. A panel of NSCLC cells lines with confirmed mutations in the EGFR kinase domain was screened for erlotinib and OSI-906 single agent drug sensitivities. All mutant EGFR models exhibited sensitivity to EGFR inhibition by erlotinib (IC50 7–33 nM) while none showed sensitivity to OSI-906 (IC50 7gt;10 uM). In vitro, the combination of erlotinib and OSI-906 resulted in synergistic inhibition of cell proliferation and induction of apoptosis in PC3 (JCP-1) cells. Mechanistically we found the combination had enhanced inhibition of signaling through the PI3K/AKT pathway compared to treatment with either single agent. We also observed that while OSI-906 showed no induction of cell death, erlotinib treatment caused almost complete cell death. However after 9 days of erlotinib treatment small colonies of viable cells still remained. Removal of drug allowed the cells to grow and expand. When cells were treated with both erlotinib and OSI-906, complete cell death occurred without any evidence of cell regrowth following removal of both drugs. In order to evaluate this combination effect in vivo the EGFR mutant human tumor xenograft models NCI-H1650 and PC-14 were employed. Both lines are highly sensitive to erlotinib single agent treatment but show no anti-tumor activity with OSI-906 single agent treatment. The combination of 100 mg/kg erlotinib and 10 mg/kg OSI-906 demonstrated enhanced tumor growth delay when compared to either single agent dosed at MTD. However, as a first step towards understanding preclinical mechanism of this interaction we investigated the combination of 25 mg/kg of erlotinib with 30 mg/kg of OSI-906 and identified potential in vivo synergy. These studies with 25 mg/kg of erlotinib and 30 mg/kg of OSI-906 showed initial tumor regressions, enhanced tumor inhibition and substantially prolonged tumor growth delay when compared to either single agent. Drug-drug interaction PK studies suggest that OSI-906 is not acting to enhance erlotinib exposure. This data provides preclinical proof-of-concept for the use of OSI-906 in combination with erlotinib to obtain greater anti-tumor activity in the mutant EGFR setting.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr LB-388. doi:10.1158/1538-7445.AM2011-LB-388

A systems view of epithelial-mesenchymal transition signaling states

Epithelial–mesenchymal transition (EMT) is an important contributor to the invasion and metastasis of epithelial-derived cancers. While considerable effort has focused in the regulators involved in the transition process, we have focused on consequences of EMT to prosurvival signaling. Changes in distinct metastable and ‘epigentically-fixed’ EMT states were measured by correlation of protein, phosphoprotein, phosphopeptide and RNA transcript abundance. The assembly of 1167 modulated components into functional systems or machines simplified biological understanding and increased prediction confidence highlighting four functional groups: cell adhesion and migration, metabolism, transcription nodes and proliferation/survival networks. A coordinate metabolic reduction in a cluster of 17 free-radical stress pathway components was observed and correlated with reduced glycolytic and increased oxidative phosphorylation enzyme capacity, consistent with reduced cell cycling and reduced need for macromolecular biosynthesis in the mesenchymal state. An attenuation of EGFR autophosphorylation and a switch from autocrine to paracrine-competent EGFR signaling was implicated in the enablement of tumor cell chemotaxis. A similar attenuation of IGF1R, MET and RON signaling with EMT was observed. In contrast, EMT increased prosurvival autocrine IL11/IL6-JAK2-STAT signaling, autocrine fibronectin-integrin α5β1 activation, autocrine Axl/Tyro3/PDGFR/FGFR RTK signaling and autocrine TGFβR signaling. A relatively uniform loss of polarity and cell–cell junction linkages to actin cytoskeleton and intermediate filaments was measured at a systems level. A more heterogeneous gain of ECM remodeling and associated with invasion and migration was observed. Correlation to stem cell, EMT, invasion and metastasis datasets revealed the greatest similarity with normal and cancerous breast stem cell populations, CD49f^hi/EpCAM^-/lo and CD44^hi/CD24^lo, respectively.

Abstract P1-01-19: Comparison of Ultrasound-Guided Fine Needles Aspiration Cytology and Ultrasound Guided Core Biopsy in Pre-Operative Axillary Staging for Early Breast Cancer

Introduction: Pre-operative axillary staging is now widely accepted as a prerequisite in surgical management of the axilla for patients newly diagnosed with early breast cancer. For those patients having breast tumour excision who are found to have nodal involvement, axillary clearance can be performed at the same time without prior sentinel node biopsy. Ultrasound (US) alone has low sensitivity, but can be used to direct needle biopsy. We assessed and compared the sensitivity and specificity of US-guided core biopsies (USCB) and US-guided fine needle cytology (USFNAC) used in our unit.

Patients and methods: A retrospective and prospective data collection was performed between November 2007 and May 2010 on all newly diagnosed breast cancer patients in our unit since the introduction of routine pre-operative axillary US. Patients whose nodes looked benign or normal on US were offered sentinel node biopsy (SNB). Patients found to have suspicious nodes were offered USFNAC or USCB, according to the individual preference of the radiologists. Patients with positive cytology or histology underwent axillary node clearances (ANC), those with benign cytology or histology were offered SNB. The final histology results were reviewed and correlated to their pre-operative histology or cytology.

Results: Of 559 Axillary ultrasound scans performed in our department between November 2007 and May 2010, 229 patients had pre-operative US scans of the axilla for newly diagnosed, clinically node-negative breast cancer. Of these 46 had USFNAC, 44 had USCB and 139 had normal/benign US. The USFNAC and USCB groups had similar proportions of positive results on postoperative histology, namely 70% and 79% respectively, allowing direct comparisons to be made. Of the 46 USFNAC patients, 17 (37%) had positive cytology (all confirmed by axillary clearance final histology). The 29 USFNAC patients with negative cytology had 15 (52%) with positive histology on sentinel node biopsy. The sensitivity of USFNAC was 53% and the specificity 100%. Of the 44 USCB patients, 26 (59%) were positive (all confirmed by axillary clearance final histology). Of the 18 USCB-negative patients, 7 (39%) were found to be positive on axillary clearance. The sensitivity of USCB was 79% and the specificity 100%. Of the 139 patients with normal US, 42 (30%) were found to be positive on sentinel node biopsies. For US alone, sensitivity was 61% and specificity was 80%.

Conclusion: US staging of the axilla is superior to clinical staging. However, there is still a high incidence of false negative results, making US a crude way of assessing the axilla and confirming the necessity for sentinel node biopsy in US-negative axillae. For patients with axillae that are indeterminate on US, our data supports routine use of ultrasound core biopsy (USCB) over Ultrasound fine needle aspiration cytology (USFNAC) for preoperative staging of the axilla, where technically feasible.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P1-01-19.

Abstract SY01-01: Adaptive protein and phosphoprotein networks which promote therapeutic sensitivity or acquired resistance

&lt;abstract&gt; Multiple signal transduction pathways can be concurrently active within a single cell, and extensive crosstalk can occur between RTKs. Additionally, tumor tissues can be comprised of a heterogeneous collection of cell states utilizing distinct RTKs for maintenance of tumor cell growth and survival. As a consequence of this complexity, many tumors may be only partially sensitive to single agent therapies and would require the interdiction of multiple RTKs and other protein signaling targets for optimal anti-cancer therapy. Understanding pathway crosstalk is vital to guide the rational combination of approved and experimental anti-cancer agents.

Receptor tyrosine kinases (RTKs) are key mediators of tumor cell survival, proliferation and migratory pathways, and inhibitors of RTKs have demonstrated anti-tumor efficacy in both the preclinical and clinical settings. Multiple sensitivity and resistance mechanisms have been described for EGF receptor inhibitors for the treatment of NSCLC. In carcinomas with an epithelial phenotype, onco-addiction and tumor progression have been associated with autocrine ligand-dependent activation of EGFR (1, 2). Notably, EGFR dependence can also occur through genetic mutations in exons 19-21 of the EGFR gene (3-5) which renders the encoded protein less able to bind ATP. Resistance can occur, primarily in these patients with these primary activating mutations, from acquisition of a secondary mutation of EGFR at the T790M gatekeeper site (6, 7) which increases ATP affinity and thereby decreases binding of ATP competitive inhibitors (8). Importantly, resistance can also occur through up regulation of alternate receptor tyrosine kinases (RTKs), and therefore understanding crosstalk between RTKs is critical for optimizing the use of RTK inhibitors in the clinic.

Tumor tissues progress from in situ to metastatic states through the reacquisition of developmental programs allowing invasion and metastasis. The acquisition of an invasive phenotype can occur by epithelial-mesenchymal transition (EMT). The molecular characteristics of epithelial and mesenchymal cell phenotypes were extensively characterized by intersection of proteomic, phosphoproteomic and gene expression profiling approaches. Tumor cells that have undergone EMT show a marked reduction in sensitivity to EGFR TKIs and anti-EGFR MAbs (9). In several instances, the EMT-derived mesenchymal-like tumor cells have gained sensitivity to PDGFR and/or FGFR1 inhibitors. Significant switching of receptor tyrosine kinases, from EGFR, Met/Ron and IGF-1R to cells utilizing PDGFR and FGFR was observed. The acquisition of autocrine fibronectin - integrin was also observed in several tumor lines and inducible models. Therefore, EMT can promote use of alternative signaling pathways.

Resistance can also derive from over activation of partially redundant pathways concurrently active in a cell. For example, activation of the IGF-1 receptor (IGF-1R) or the HGF receptor (Met) has been shown to obviate the need for EGFR signaling in epithelial-derived lung tumors (10). Crosstalk has been well documented with EGF, HGF and IGF1 receptors. These receptors, when activated by ligand binding, can create network redundancies (for example by IGF stimulation of EGFR onco-addicted cells; (11)). Reciprocal activation of one receptor following the inhibition of a distinct receptor has also been observed. For example PDGFRα was observed to be activated and substrates phosphorylated when EGFR was inhibited in the NSCLC line H1703(12). These studies involved a quantitative anti-phosphotyrosine profiling (13) coupled to an LC-MS/MS shotgun approach. In a second example in the Ewings sarcoma line A673, IGF-1R inhibition, by kinase inhibition resulted in the reciprocal activation of the insulin receptor and cell survival (14). We have previously shown reciprocal activation of EGFR by IGF1R inhibition and activation of IGF1R through EGFR inhibition (15). The mechanisms by which reciprocity is achieved are under investigation. The ability of tumor cells to reciprocally induce alternative RTKs following the inhibition of a given receptor (in this case EGFR or IGF1R) highlights the need for rational combination anti-cancer therapy.

One RTK may also positively affect the activity of another in a process that can be termed receptor co-option. Here, one dominant ligand-stimulated RTK, possibly amplified or mutated, directly or indirectly tyrosine phosphorylates additional RTKs to create functional signaling scaffolds and to engage signaling networks beyond the normal capabilities of the original dominant kinase. Where the co-option of RTK signaling networks is observed, markers of RTK activation (e.g. the extent of receptor tyrosine phosphorylation) are not necessarily predictive of onco-addiction. Direct or indirect crosstalk between EGFR, ErbB2, Met, Ron and other RTKs has been observed in a bidirectional manner. Crosstalk can occur on the RON Y1238/Y1239 autophosphorylation site where MET and/or EGFR are the active kinases. Such phosphorylation in trans (either direct or indirect) may promote RON kinase activity in the absence of ligand. Alternatively or in addition, cross phosphorylation of RTKs in trans can allow signaling scaffolds to be established, mimicking kinase activation in the absence of ligand. Three NSCLC models illustrate co-option of RTKs as described below:

The NSCLC line H1650 harbors a gain-of-function exon 19 deletion that is strongly onco-addicting in adenocarcinoma of the lung and is often associated with exquisite sensitivity to EGFR blockade. Pharmacological inhibition of EGFR in H1650 by the EGFR-ErbB2 inhibitor erlotinib results in a rapid dephosphorylation of ErbB2, Src family kinases and the direct and downstream substrates Cbl-B and Erk2 respectively. Interestingly attenuation of Met tyrosine phosphorylation is also observed suggesting that hyperactive mutant EGFR (del19) can also co-opt additional RTKs.

In the NSCLC line H292, ~50% of the tyrosine phosphate on Met and on Ron is inhibitable by EGFR blockade. Crosstalk between EGFR, Met and Ron kinases was measured by combined anti-phosphotyrosine immunoaffinity selection, stable isotope peptide labeling (iTRAQ) and LC-electrospray tandem MS. The phosphotyrosine content on Met and Ron was decreased following exposure to erlotinib relative to mock control cells. The inhibition of phospho-Met and phospho-Ron followed kinetics for the erlotinib-dependent decrease in the SH2 adapter proteins phospho-SHC, -Erk2 and Grb2. The data suggest either direct phosphorylation of Met and Ron by EGFR or rapid recruitment and activation of intermediary non-transmembrane tyrosine kinases. These non-transmembrane tyrosine kinases could include Src/Yes/Fyn family kinases or Brk family kinases, possibly in a cell-specific manner, but this remains to be tested.

A more extreme example of co-option of diverse kinase signaling networks by a single RTK is observed in the NSCLC H1993 cell line. Here exposure to small molecule Met tyrosine kinase inhibitors attenuated both Met and Met-associated SH2/PTB domain adapter proteins as well as more distantly related RTK signaling networks. Exposure of H1993 epithelial carcinoma cells to Met inhibitors markedly inhibited ~250 Met substrates, both known and unknown, including the cell surface signaling proteins Met, Ron, EGFR, ErbB2, DDR1, CSFR2, ITG4, ITG6, EphA2, EphB4. This in turn results in a comparatively complete dephosphorylation of a wide array of signaling adaptors, cell-cell junction proteins, cytoskeletal reorganizing elements and folding chaperones. While marked attenuation of EGFR was observed in response to Met inhibition alone, the combination of both Met and EGFR inhibitors was required for full dephosphorylation of both Erk1/2 and STAT5A. These findings suggest that while Met can co-opt EGFR, phosphorylate EGFR, and establish initial SH2/PTB domain dependent complexes on EGFR via active Met kinase, the extent of Met-dependent EGFR tyrosine phosphorylation is insufficient for full Erk and STAT5 activation. Several conclusions can be drawn. First, Met is the principle source of phosphotyrosine in H1993, and the cell line is likely onco-addicted solely to Met. Second, Met essentially ‘highjacks’ other RTKs as signaling adapters. Third, effective blockade of Erk activation was only observed with dual Met and EGFR inhibition suggesting synergy relies on erlotinib directed Erk inhibition in the H1993 model.

The quantitative measurement of cancer cell signaling under dynamic conditions of pharmacological or siRNA mediated inhibition of specific signaling nodes gives insight into the requirements for effective cellular blockade of survival and invasive networks associated with cancer progression. The use of quantitative shotgun LC-MS/MS methods incorporating stable isotopes provides a rapid means to identify proteins and phosphoproteins perturbed in particular cancer cell states. These methods have allowed interrogation of RTK crosstalk in tumor cell lines and xenografts so as to generate specific hypotheses relating to targeted drug combinations. In addition such data have better defined the role of EMT in survival signaling switching and anticancer drug resistance, again suggesting combination therapy options for further investigation.

References

1. Han et al Br J Cancer 2009.

2. Jacobs et al J Clin Oncol 2009.

3. Lynch et al N Engl J Med 2004.

4. Paez et al Science 2004.

5. Pao et al Proc Natl Acad Sci 2004.

6. Bell et al Nat Genet 2005.

7. Pao et al PLoS Med 2005.

8. Carey et al Cancer Res 2006.

9. Barr et al Clin Exp Metastasis 2008.

10. Engelman et al Science 2007.

1.1 Thelemann et al Mol Cell Proteomics 2005.

12. Thomson et al Clin Exp Metastasis 2008.

13. F. Petti et al Mol Cancer Ther 2005.

14. E. Buck manuscript submitted.

15. E. Buck et al Cancer Res 2008.

Citation Format: John D. Haley, Stuart Thomson, James Bean, Ruixi Xie, David Epstein, Mark Miglarese, Liz Buck. Adaptive protein and phosphoprotein networks which promote therapeutic sensitivity or acquired resistance [abstract]. In: Proceedings of the AACR 101st Annual Meeting 2010; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr SY01-01

Abstract 1463: Pharmacological impact of epithelial-mesenchymal plasticity in the H358 lung tumor model

The phenotypic changes associated with epithelial to mesenchymal transition (EMT) give tumor cells at least two attributes that increase metastatic efficiency. First, mesenchymal cells have lost cell-cell contacts and are more invasive and can therefore escape the primary tumor, whereas epithelial cells remain anchored by cell-cell contacts in the primary tumor. Second, mesenchymal cells in vitro are less sensitive than epithelial cells to agents that inhibit the EGFR pathway. This appears to translate into the clinic, since patients with tumors that express mesenchymal markers do not respond to EGFR targeting therapeutics as well as patients with more epithelial tumors. To determine whether we can control sensitivity to EGFR inhibitors by manipulating a cell's epithelial/mesenchymal status, we examined the role of EMT and its reversibility in tumor cell sensitivity to the EGFR inhibitor erlotinib. We studied in vitro models of EMT driven by Transforming Growth Factor β (TGFβ), Hepatocyte Growth Factor + Oncostatin M (HGF+OSM), Snail or Zeb1 in the H358 non-small cell lung carcinoma model. EMT driven by TGFβ or HGF+OSM caused a significant decrease in sensitivity to erlotinib, while EMT driven by induced expression of Snail or Zeb1 was much less effective, suggesting a change in drug sensitivity requires more input than these canonical EMT transcription factors. Once mesenchymal tumor cells have localized to a metastatic site, it is thought the tumor cells must undergo a mesenchymal to epithelial transition (MET) in order to form a cohesive tumor. We examined the reversibility of EMT in our models and the corresponding erlotinib sensitivity, both by withdrawal of ligand and by pharmacological inhibition of the signaling pathways downstream of the drivers. Using these approaches, we found EMT driven by HGF+OSM was reversible as evidenced by morphology and marker changes, and this reversion correlated with an increase in erlotinib sensitivity, comparable to the parental H358 cells. EMT driven by TGFβ was partially reversed by both ligand withdrawal and pharmacological inhibition of the receptor, and the extent of reversion in erlotinib sensitivity correlated with the extent of marker reversion. These results demonstrate that the extent of reversibility of EMT is dependent on the driver. Furthermore, it may be possible to drive some erlotinib-insensitive tumors back to a more erlotinib-sensitive state with pharmacological agents, thus improving patient response.

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 1463.

Hair analysis provides a historical record of cortisol levels in Cushing's syndrome

The severity of Cushing's Syndrome (CS) depends on the duration and extent of the exposure to excess glucocorticoids. Current measurements of cortisol in serum, saliva and urine reflect systemic cortisol levels at the time of sample collection, but cannot assess past cortisol levels. Hair cortisol levels may be increased in patients with CS, and, as hair grows about 1 cm/month, measurement of hair cortisol may provide historical information on the development of hypercortisolism. We attempted to measure cortisol in hair in relation to clinical course in six female patients with CS and in 32 healthy volunteers in 1 cm hair sections. Hair cortisol content was measured using a commercially available salivary cortisol immune assay with a protocol modified for use with hair. Hair cortisol levels were higher in patients with CS than in controls, the medians (ranges) were 679 (279-2500) and 116 (26-204) ng/g respectively (P<0.001). Segmental hair analysis provided information for up to 18 months before time of sampling. Hair cortisol concentrations appeared to vary in accordance with the clinical course. Based on these data, we suggest that hair cortisol measurement is a novel method for assessing dynamic systemic cortisol exposure and provides unique historical information on variation in cortisol, and that more research is required to fully understand the utility and limits of this technique.

An assessment of cortisol analysis in hair and its clinical applications

Hair analyses for exogenous compounds, specifically drugs of abuse, have been a useful tool in detecting long-term drug exposure. More recently, studies have delved into the exposure of endogenous compounds in hair. Cortisol is synthesized in the adrenal cortex in response to stress-induced activation of the hypothalamic-pituitary-adrenal (HPA) axis. While catecholamines generally indicate acute stress, cortisol can be used as an indicator for sub-acute and chronic stress. Studies on the effects of chronic stress are most often subjective in nature, relying on questionnaires asking the participant to recall on past stressors. This can lead to the issue of recall and reporting bias. A new objective measure of chronic stress is needed for a more accurate understanding of the effects of chronic stress on the body. This review uses emerging evidence to describe the usefulness of hair analysis for cortisol and discusses the current methods used.