RhoA downregulation in the murine intestinal epithelium results in chronic Wnt activation and increased tumorigenesis

Rho GTPases are molecular switches regulating multiple cellular processes. To investigate the role of RhoA in normal intestinal physiology, we used a conditional mouse model overexpressing a dominant negative RhoA mutant (RhoAT19N) in the intestinal epithelium. Although RhoA inhibition did not cause an overt phenotype, increased levels of nuclear β-catenin were observed in the small intestinal epithelium of RhoAT19N mice, and the overexpression of multiple Wnt target genes revealed a chronic activation of Wnt signaling. Elevated Wnt signaling in RhoAT19N mice and intestinal organoids did not affect the proliferation of intestinal epithelial cells but significantly interfered with their differentiation. Importantly, 17-month-old RhoAT19N mice showed a significant increase in the number of spontaneous intestinal tumors. Altogether, our results indicate that RhoA regulates the differentiation of intestinal epithelial cells and inhibits tumor initiation, likely through the control of Wnt signaling, a key regulator of proliferation and differentiation in the intestine.

Abstract 95: High Proportion Of Granulocytes Form Intracranial Thrombus Is Associated With Increased Stiffness And Resistance To Endovascular Recanalization

Hypothesis: We aim to identify a profile of intracranial thrombus resistant to recanalization by standard mechanical thrombectomy (MT) in acute stroke treatment.

Methods: First extracted clot of each MT were analyzed by Flow Cytometry obtaining composition of main leukocyte populations: granulocytes, monocytes and lymphocytes. Demographics, reperfusion treatment and grade of recanalization were registered. MT Failure ( MTF) was defined as final Thrombolysis in Cerebral Infarction score IIa or lower and/ or need of permanent intracranial stenting as a rescue therapy after standard MT. In other cohort of cases, unconfined compression tests were performed to explore stiffness of retrieved clots . We looked for correlation between mechanical characterization tests and clot composition.

Results: Among 225 patients, there were 13 % of MTF that were significantly associated to atherosclerosis etiology ( 33.3% vs. 15.9% ; p 0.021) , more passes ( 3 vs. 2; p <0.001), higher proportion of clot granulocytes ( 82.46% vs. 68.90% ; p <0.001) and lower proportion of clot monocytes ( 9.18% vs.17.34% ; p<0.001). The proportion of clot granulocytes (aOR 1.07; 95% CI 1.01-1.14) remained as an independent marker of MTF. Among Thirty eight clots tested by unconfined compression median clot stiffness was 30.2 (IQR, 18.9-42.7) kPa. There was a positive correlation between granulocyte proportion and thrombi stiffness (Pearson’s r=0.35, p=0.032).

Conclusions: There is a positive correlation between granulocyte proportion and thrombi stiffness that may explain endovascular resistance to recanalization. Influence of granulocytes within thrombus may be a target for future reperfusion treatments.

Integrating digital pathology with transcriptomic and epigenomic tools for predicting metastatic uterine tumor aggressiveness

The incidence of new cancer cases is expected to increase significantly in the future, posing a worldwide problem. In this regard, precision oncology and its diagnostic tools are essential for developing personalized cancer treatments. Digital pathology (DP) is a particularly key strategy to study the interactions of tumor cells and the tumor microenvironment (TME), which play a crucial role in tumor initiation, progression and metastasis. The purpose of this study was to integrate data on the digital patterns of reticulin fiber scaffolding and the immune cell infiltrate, transcriptomic and epigenetic profiles in aggressive uterine adenocarcinoma (uADC), uterine leiomyosarcoma (uLMS) and their respective lung metastases, with the aim of obtaining key TME biomarkers that can help improve metastatic prediction and shed light on potential therapeutic targets. Automatized algorithms were used to analyze reticulin fiber architecture and immune infiltration in colocalized regions of interest (ROIs) of 133 invasive tumor front (ITF), 89 tumor niches and 70 target tissues in a total of six paired samples of uADC and nine of uLMS. Microdissected tissue from the ITF was employed for transcriptomic and epigenetic studies in primary and metastatic tumors. Reticulin fiber scaffolding was characterized by a large and loose reticular fiber network in uADC, while dense bundles were found in uLMS. Notably, more similarities between reticulin fibers were observed in paired uLMS then paired uADCs. Transcriptomic and multiplex immunofluorescence-based immune profiling showed a higher abundance of T and B cells in primary tumor and in metastatic uADC than uLMS. Moreover, the epigenetic signature of paired samples in uADCs showed more differences than paired samples in uLMS. Some epigenetic variation was also found between the ITF of metastatic uADC and uLMS. Altogether, our data suggest a correlation between morphological and molecular changes at the ITF and the degree of aggressiveness. The use of DP tools for characterizing reticulin scaffolding and immune cell infiltration at the ITF in paired samples together with information provided by omics analyses in a large cohort will hopefully help validate novel biomarkers of tumor aggressiveness, develop new drugs and improve patient quality of life in a much more efficient way.

Abstract TP255: Lymphocytes And Platelets In Extracted Thrombus May Indicate The Etiology Of The Thrombus. Results From The Itacat Multicentric Registry

Aim: We performed a histological and immune analysis of the clot in acute stroke patients to detect surrogates of stroke etiology.

Methods: We conducted a prospective observational study of consecutive patients with acute stroke who underwent thrombectomy that obtained extracted thrombus (ITACAT study). Several staining were performed to evaluate red blood cells/fibrin (hematoxylin/eosin), platelets (CD61) and leucocytes (CD4, CD8 and CD20). All patients received CT angio to detect extra/intracranial vascular stenosis and 30-day cardiac monitoring to diagnose AF. According to TOAST classification the thrombi were classified in cardioembolic etiology CE (T-CE), due to symptomatic atherosclerosis (T-AT) and without any cause (T-CRYP). We excluded strokes due to double cause or incomplete workup.

Results: Of the 117 patients: 30 were T-AT, 55 were T-CE and 32 were T-CRYP. T-AT patients were younger: T-AT 68 years (60-77) Vs. T-CE 75 years (68-80) Vs. T-CRYP 72 years (55-81) (p=0.034). T-AT group had higher percentage of CD4: T-AT 6.52% (4-13) Vs. T-CE (3.31% (12.9) Vs .T-CRYP 3.72% (1.5-12) (p=0.015) and lower percentage of CD61: T-AT 51.18% (34-68) Vs. CE 64.70% (19.56) Vs. CRYP 70.3% (19) (p=0.001). There were no correlation between CD4 and platelets. Both CD4 OR 1.05 (1-1.10) (p=0.020) and CD61 (OR 0.96 (0.94-0.98) (p=0.01) independently predicted T-AT from the age. Final analysis (n=400 cases) will be ended in September 2021.

Conclusions: Patients with high percentage of CD4 and low percentage of CD61 are related to atherosclerosis etiology.

Abstract 138: Thrombus Composition Is Associated With First Pass Recanalization

Introduction: Our objective is to identify thrombus composition associated with first pass recanalization (FPR) in mechanical thrombectomy (MT).

Methods: Intracranial thrombi obtained in MT were divided in two equal parts. One part was analyzed with anatomopathological studies to quantify fibrin, red-blood cell( Hematoxilin & Eosin) and platelets( cd61 Immunohistochemical staining ) , the other part was analyzed by flow cytometry to quantify leukocyte populations (granulocytes, lymphocytes and monocytes) and their relative proportions . FPR were defined as ≥ mTICI 2b after first pass in MT. Thrombi composition, baseline variables (demographics, previos use of antiplatelets or anticoagulants, blood pressure and blood glucose at hospital arrival ) etiology, intravenous fibrinolysis, ASPECTS score and first attempt thrombectomy devices: direct aspiration, stent retriever or combinations were compared between FPR and Non-FPR groups.

Results: Fifty percent (38/76) of the cases analyzed obtained FPR. There were no differences in baseline variables , etiology, Aspects score, previous use of fibrinolysis or type of device used for MT. The thrombi obtained with FPR presented higher proportion of red blood cells (33.64% vs 18.16% p = 0.048) and lymphocytes (10.07% vs 4.43% p = 0.042) and lower proportion of platelets (61, 48% vs 67.26% p = 0.042) in comparison to non-FPR group. The proportion of platelets was an independent marker of FPR (OR 0.97; CI 0.95-0.99). There was an inverse correlation between the proportion of platelets and lymphocytes (rho -0.44, p <0.001).

Conclusion: Platelets proportion in intracranial thrombus is an independent marker of first pass recanalization. Inverse relationship between lymphocytes and platelets may be a target for future reperfusion treatments

Abstract P779: Monocyte to Lymphocyte Ratio in Clot Analysis is a Marker of Cardioembolic Stroke Etiology

Methods: We analyzed data from 190 patients in a prospective unicentric study. Thrombi obtained in emergent endovascular treatment ( EVT) were analyzed by MFC order to calculate the percentage of granulocytes , monocytes and lymphocytes, over total leukocyte population as well as monocyte-to-lymphocyte ratio ( MLR) Clinical and interventional parameters were recorded for each patient. Stroke subtypes were defined by the Trial of ORG 10172 in Acute Stroke Treatment classification. We tested MFC predictors of high risk cardioembolic strokes (HR CE) in patients with undetermined stroke etiology . MFC predictor was obtained by comparison of clots due to Large Arterial Atherosclerosis compared with clots due to HR CE.

Results: Among 190 clots retrieved, 163 cases were properly analized. 91 cases with known stroke etiology after EVT and 72 cases of Undetermined stroke. In a demographic (age, gender) and EVT matched (time, tpa, number of passes) case -control study of 56 patients: HR CE strokes (28 cases) and LAA strokes (28 cases), the proportion of monocytes ( OR 1.06 , 95% CI 1.01- 1.11) and MLR ( OR 1.83 , 95% CI 1.12- 2.98) independently predicted HR CE detection. A cut-off point of 1.77% in a receiver operating characteristic curve predicted cardiomebolic etiology with sensitivity of 71% and specificity of 82%. Among Undetermined Strokes (n=72) the percentage of HR CE detection was higher in patients with high MLR (n=40 ; 74%) compared with low MLR (n=6; 33%) ( p< 0.001). Patients with high MLR were older than low MLR cases, although MLR > 1.77 independently predicted HR CE detection among Undetermined strokes (OR, 4.50 ,95% CI 1.35-15.04) in a multivariate model adjusted for age.

Conclusion: Measurement of monocyte to lymphocyte ratio in clots by multiparametric flow cytometry detected patients at high risk of hidden cardioembolic origin among undetermined stroke population.

Clinical and molecular practice of European thoracic pathology laboratories during the COVID-19 pandemic. The past and the near future

Background

This study evaluated the consequences in Europe of the COVID-19 outbreak on pathology laboratories orientated toward the diagnosis of thoracic diseases.

Materials and methods

A survey was sent to 71 pathology laboratories from 21 European countries. The questionnaire requested information concerning the organization of biosafety, the clinical and molecular pathology, the biobanking, the workload, the associated research into COVID-19, and the organization of education and training during the COVID-19 crisis, from 15 March to 31 May 2020, compared with the same period in 2019.

Results

Questionnaires were returned from 53/71 (75%) laboratories from 18 European countries. The biosafety procedures were heterogeneous. The workload in clinical and molecular pathology decreased dramatically by 31% (range, 3%-55%) and 26% (range, 7%-62%), respectively. According to the professional category, between 28% and 41% of the staff members were not present in the laboratories but did teleworking. A total of 70% of the laboratories developed virtual meetings for the training of residents and junior pathologists. During the period of study, none of the staff members with confirmed COVID-19 became infected as a result of handling samples.

Conclusions

The COVID-19 pandemic has had a strong impact on most of the European pathology laboratories included in this study. Urgent implementation of several changes to the organization of most of these laboratories, notably to better harmonize biosafety procedures, was noted at the onset of the pandemic and maintained in the event of a new wave of infection occurring in Europe.

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Biosafety measures used in the first wave of the COVID-19 crisis were heterogeneous in 53 European pathology laboratories.

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A dramatic decrease of the workload in pathology laboratories was noted.

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No case of healthcare workers contaminated with SARS-CoV-2 associated with samples handling was identified.

Abstract WMP62: High Linfocytes B Cells In Intracranial Thrombi Represent A Biomarker Of Atherothrombotic Stroke

Approximately 30% of strokes are cryptogenic despite an exhaustive in-hospital work-up Analysis of clot composition following endovascular treatment could provide insight into stroke etiology.

Objective: To evaluate different population of lymphocytes in the clot analyses obtained in the hyper acute phase of stroke, as an early marker of etiology of ischemic stroke.

Material and Methods: Consecutively, intracranial clots were obtained in the hyper acute phase of stroke in endovascular treatment with solitaire device and analyzed by flow cytometry quantifying the relative proportion ( RP ) of main leukocyte, monocyte, granulocyte and total lymphocyte populations and lymphocyte sub populations of B line (CD19), T line (CD3, CD4, CD8), Cytotoxic and Natural Killer. The results were expressed as percentages (%). All patients included were studied with complete diagnostic work up that included at least complete arteriography , aortic Angio CT , complete cardiac holter monitoring until one month form hospital discharge and transthoracic echocardiography , The etiology of stroke was categorized: cardiomebolic ( major structural heart disease and Atrial Fibrillation) atherosclerotic ( AT) (severe symptomatic arterial stenosis or complicated aortic atheromatosis ulceration confirmed by trans esophageal echocardiography ) ,infrequent causes or unknown etiology .

Results: 80 patients were included. 22, 5% AT (n = 18) strokes were associated with higher RP lymphocytes PR (16.55 % vs. 5. 37 % p < 0,001), CD4 RP (5.74% vs. 2.03 % p = 0.001) and RP CD 19 (2.26 % vs. 0.37 % p< 0,001) in clot cytometry Analysis than rest of of strokes etiologies (n= 72). Multivariate logistic regression analysis showed that RP CD 19 (OR 3.51; 95% CI, 1, 81-6.81) was an independent predictor of atherosclerotic stroke .The ROC curve showed AUC (0.83) (95% CI, 0.72-0.95) for RP CD 19 for diagnosis of atherosclerotic strokes with flow cytometry of the clot ,obtained in emergent endovascular treatment.

Conclusion: High expression of lymphocytes B in intracranial thrombi is a marker of atherosclerotic etiology.

Abstract B40: Intratumor heterogeneity in lung adenocarcinoma: Beyond genetics

Background: For decades, pathologists have been describing new anatomopathological entities in lung carcinomas emphasizing the great heterogeneity of intratumor cell growth patterns. Modern genomic studies have identified a vast number of genetic alterations throughout the whole tumor and metastasis. In lung, oncogenic drivers such as EGFR, ALK, ROS, and RAS are mutated or translocated in a significant number of adenocarcinomas. Because genetic alteration can be heterogeneous, we studied DNA mutations and RNA expression in three different areas of the tumors, as well as protein expression of receptors and signaling factors in whole lung carcinomas sections.

Material and Methods: In 130 lung adenocarcinomas the histopathological features were assessed as well as the expression of ALK, HER2, ki67, pMAPK, mtor, 4E-BP1, p4E-BP1, eIF4E, peIF4E, and Epithelial-Mesenchymal Transition (EMT) factors (N-cadherin, YB1, pYB1) by specific antibodies in whole paraffin sections. Homogeneous expression was considered when &gt;80% tumor cells displayed a strong positivity. In 30 adenocarcinomas, molecular studies were run in three different histological cores with acinar, papilar and micropapilar cell growth patterns. DNA extraction for detection of mutations of EGFR and KRAS and RNA extraction, and gene expression of 110 genes was screened using NanoString technology.

Levels of expression were evaluated semi quantitatively as percentage and intensity of stained tumor cells (histo-score [H score]) and correlations were analyzed using Kruskal-Wallis and Kaplan-Meier (log Rank) statistical tests.

Results: The predominant histological subtypes were acinar, papillary and solid, with the latter associated with higher histological grade and more necrosis. p4E-BP1 and peIF4E displayed a homogenous and diffuse protein expression in about 80% of tumors. High expression of eIF4E, 4EBP1 and YB1 was associated with higher recurrence rate, histological grade and metastases. Regarding RNA expression, 90% of cases showed intratumoral heterogeneity in some genes. EGFR mutations show a heterogeneous distribution in about 20% cases while KRAS mutations were positive in all the areas of the tumors.

Conclusions: In lung adenocarcinomas, there is intratumor heterogeneity of mRNA expression in most cases, of EGFR mutations in a significant number of cases and a striking diversity in protein expression. With this data, several conclusions can be drawn: first, the importance to study several areas of the tumors to assess tumor heterogeneity both at molecular and protein levels; second, the patchy expression of signaling factors, probably due to local factors such as hypoxia, may explain partial clinical responses, third, in most cases peIF4E displayed a homogeneous expression supporting its role as a therapeutical target and fourth, pathologists need to integrate the molecular data, protein and histopathological data and apply systems biology and topologic approaches to highlight the more relevant prognostic information and therapeutical options for each tumor and patient.

Citation Format: Santiago Ramon y Cajal. Intratumor heterogeneity in lung adenocarcinoma: Beyond genetics. [abstract]. In: Proceedings of the AACR Special Conference on Translational Control of Cancer: A New Frontier in Cancer Biology and Therapy; 2016 Oct 27-30; San Francisco, CA. Philadelphia (PA): AACR; Cancer Res 2017;77(6 Suppl):Abstract nr B40.

Investigation of the role of tyrosine kinase receptor EPHA3 in colorectal cancer

EPH signaling deregulation has been shown to be important for colorectal carcinogenesis and genome-wide sequencing efforts have identified EPHA3 as one of the most frequently mutated genes in these tumors. However, the role of EPHA3 in colorectal cancer has not been thoroughly investigated. We show here that ectopic expression of wild type EPHA3 in colon cancer cells did not affect their growth, motility/invasion or metastatic potential in vivo. Moreover, overexpression of mutant EPHA3 or deletion of the endogenous mutant EPHA3 in colon cancer cells did not affect their growth or motility. EPHA3 inactivation in mice did not initiate the tumorigenic process in their intestine, and had no effects on tumor size/multiplicity after tumor initiation either genetically or pharmacologically. In addition, immunohistochemical analysis of EPHA3 tumor levels did not reveal associations with survival or clinicopathological features of colorectal cancer patients. In conclusion, we show that EPHA3 does not play a major role in colorectal tumorigenesis. These results significantly contribute to our understanding of the role of EPH signaling during colorectal carcinogenesis, and highlighting the need for detailed functional studies to confirm the relevance of putative cancer driver genes identified in sequencing efforts of the cancer genome.

Cerebrospinal fluid-derived circulating tumour DNA better represents the genomic alterations of brain tumours than plasma

Cell-free circulating tumour DNA (ctDNA) in plasma has been shown to be informative of the genomic alterations present in tumours and has been used to monitor tumour progression and response to treatments. However, patients with brain tumours do not present with or present with low amounts of ctDNA in plasma precluding the genomic characterization of brain cancer through plasma ctDNA. Here we show that ctDNA derived from central nervous system tumours is more abundantly present in the cerebrospinal fluid (CSF) than in plasma. Massively parallel sequencing of CSF ctDNA more comprehensively characterizes the genomic alterations of brain tumours than plasma, allowing the identification of actionable brain tumour somatic mutations. We show that CSF ctDNA levels longitudinally fluctuate in time and follow the changes in brain tumour burden providing biomarkers to monitor brain malignancies. Moreover, CSF ctDNA is shown to facilitate and complement the diagnosis of leptomeningeal carcinomatosis.

DNA circulating in the plasma of cancer patients carries features of the primary tumour, however such DNA is found in low levels in brain cancer patients. Here, the authors show that circulating tumour DNA can be detected in the cerebral spinal fluid of cancer patients and that this better recapitulates the primary tumour compared to DNA from the plasma.

Abstract 930: Analysis of cell-free tumor DNA in cerebrospinal fluid to characterize and monitor the genetic alterations of brain tumors

Background: Genetic characterization and monitoring of brain tumors is challenging given the restricted sampling of tumors and the limited abundance of brain tumor-derived circulating tumor DNA (ctDNA) in the plasma. Here, we sought to define whether cerebrospinal fluid (CSF) could serve as a ‘liquid biopsy’ for the genetic characterization of tumor DNA originated from the central nervous system (CNS) of patients (pts) with brain tumors.

Methods: CSF, plasma and tumor tissue were obtained from pts with glioblastoma (GBM), brain metastases from breast (BMBC) and lung cancers (BMLC) and leptomeningeal carcinomatosis (LC). Whole exome sequencing was done in CSF and tumor (n = 3) and was coupled with digital PCR for monitoring CSF and plasma ctDNA (n = 6). Targeted capture massively parallel sequencing of 39 samples from 4 BMBC pts, including samples from CSF, plasma and matched metastatic sites obtained at autopsy was performed using two independent platforms (MSK-IMPACT (341 genes) and BC panel (254 genes most frequently mutated in BC)) comprising 488 unique genes. Sequencing was performed on an Illumina HiSeq2000. Single nucleotide variants were defined using MuTect, and indels using Varscan. Copy number alterations were assessed using Varscan2 and GISTIC.

Results: Whole exome sequencing of tumor and CSF DNA revealed a high proportion of tumor-derived cell-free DNA in the CSF of 3 pts (1 GBM, 2 BMBC). We identified actionable somatic mutations (EGFR L858R, IDH1 R132H) and also IDH1 mutations associated with molecular diagnosis of proneural GBM. In CSF and plasma ctDNA of 6 pts with GBM, BMBC, BMLC, we observed that the mutations present in the CSF ctDNA, but not plasma ctDNA, and their mutant allele fractions (MAFs) correlated with brain tumor burden. In 3 pts with suspected LC, we compared the results of cytopathologic analysis and CSF ctDNA obtained from samples used for cytopathologic diagnosis, and observed that CSF ctDNA was more robust and sensitive for the diagnosis of LC. The analysis of synchronous CSF ctDNA, plasma ctDNA and intra- and extra-cranial metastases from 4 autopsied BMBC pts showed that CSF ctDNA recapitulated the somatic genetic alterations present in the intra-cranial lesions. We detected similar MAFs for the truncal mutations (RB1, KMT2D, AHNAK2) in both CSF and plasma DNA of BMBC3, a pt with Li-Fraumeni syndrome and a diagnosis of concurrent BMBC and esthesioneuroblastoma; however, mutations in PIK3CB, PAK7, MSH5 found only in the CNS implant of each disease were only detected in the CSF but not in the plasma DNA.

Conclusions: Brain tumor-derived ctDNA is abundantly present in the CSF of brain cancer pts and compared to plasma ctDNA, CSF ctDNA is more representative of the brain lesions. Our results demonstrate that massively parallel sequencing can be performed using CSF DNA, allowing for the non-invasive genomic characterization and monitoring of brain lesions.

Citation Format: Leticia De Mattos-Arruda, Regina Mayor, Charlotte K. Y. Ng, Britta Weigelt, Francisco Martínez-Ricarte, Davis Torrejon, Mafalda Oliveira, Carolina Raventos, Alexandra Arias, Elena Guerini-Rocco, Elena Martínez-Sáez, Sergio Lois, Oscar Marín, Xavier de la Cruz, Salvatore Piscuoglio, Russell Towers, Ana Vivancos, Vicente Peg, Santiago Ramon y Cajal, Jordi Rodon, Enriqueta Felip, Joan Sahuquillo, Josep Tabernero, Javier Cortes, Jorge S. Reis-Filho, Joan Seoane. Analysis of cell-free tumor DNA in cerebrospinal fluid to characterize and monitor the genetic alterations of brain tumors. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 930. doi:10.1158/1538-7445.AM2015-930

Identification of somatic gene mutations in penile squamous cell carcinoma

There is a lack of studies on somatic gene mutations and cell signaling driving penile carcinogenesis. Our objective was to analyze somatic mutations in genes downstream of EGFR in penile squamous cell carcinomas, especially the mTOR and RAS/MAPK pathways. We retrospectively analyzed somatic mutations in 10 in situ and 65 invasive penile squamous cell carcinomas by using Sequenom's Mass Spectrometry iPlex Technology and Oncocarta v1.0 Panel. The DNA was extracted from FFPE blocks and we identified somatic missense mutations in three in situ tumors and in 19 invasive tumors, mostly in PIK3CA, KRAS, HRAS, NRAS, and PDGFA genes. Somatic mutations in the PIK3CA gene or RAS family genes were neither associated with tumor grade, stage or outcome, and were equally often identified in hrHPV positive and in hrHPV negative tumors that showed no p53 expression. Mutations in PIK3CA, KRAS, and HRAS are frequent in penile squamous cell carcinoma and likely play a role in the development of p53-negative tumors. Although the presence of these mutations does not seem to correlate with tumoral behavior or outcome, they could be biomarkers of treatment failure with anti-EGFR mAb in patients with penile squamous cell carcinoma.

Myo5b knockout mice as a model of microvillus inclusion disease

Inherited MYO5B mutations have recently been associated with microvillus inclusion disease (MVID), an autosomal recessive syndrome characterized by intractable, life-threatening, watery diarrhea appearing shortly after birth. Characterization of the molecular mechanisms underlying this disease and development of novel therapeutic approaches is hampered by the lack of animal models. In this study we describe the phenotype of a novel mouse model with targeted inactivation of Myo5b. Myo5b knockout mice show perinatal mortality, diarrhea and the characteristic mislocalization of apical and basolateral plasma membrane markers in enterocytes. Moreover, in transmission electron preparations, we observed microvillus atrophy and the presence of microvillus inclusion bodies. Importantly, Myo5b knockout embryos at day 20 of gestation already display all these structural defects, indicating that they are tissue autonomous rather than secondary to environmental cues, such as the long-term absence of nutrients in the intestine. Myo5b knockout mice closely resemble the phenotype of MVID patients and constitute a useful model to further investigate the underlying molecular mechanism of this disease and to preclinically assess the efficacy of novel therapeutic approaches.

Clinical and molecular characterization of refractory BRAF mutant metastatic colorectal carcinoma (mCRC): Vall d’Hebron Institute of Oncology phase I program cohort

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Background: BRAF mutation (mt) occurs in 5-8% of mCRC and its role as a negative prognostic factor is well known. The up-front detection of BRAF mt is not standardized beyond the boundaries of research. However, since novel emerging specific therapies are increasingly available in clinical trials, the prior determination of this mutation is now warranted. Methods: From 07/2010 to 01/2014, 581 patients (pts) with advanced refractory mCRCunderwent genetic tumor profiling as part of the VHIO Phase I Trial Molecular Prescreening Program. BRAF mt was determined by Sanger sequencing or multiplex PCR and mass detection (MassARRAY, Sequenom) of 268 frequent hotspots in 25 oncogenes including, KRAS, NRAS, and PIK3CA. PTEN status was also assessed by immunohistochemistry. Results: 581 samples were analyzed detecting BRAF mt in 56 (9.6%). In the BRAF mt population, median age was 61 years (45-80) and 54% had right-sided CRC. Metastatic sites were found at: liver 61%; peritoneum 52%; lung 39%. Median number of standard treatment was 4 (0-8) including cetuximab and/or panitumumab in 73%. BRAF V600E mutation was detected in 53 samples whereas V600K, D594V and D594G were seen in one sample each. PTEN was analyzed in 44.6% of samples resulting in low expression (H-score <50) in 56%. Other co-existing mutations were PIK3KCA H1047R, PIK3CA E545K, NRAS G12V, GNAS R201C and EGFR S768I. 22 pts were enrolled at least in one phase I trial with drugs targeting either BRAF alone (n=12) or combined with anti-EGFR (n=5), MEK (n=2), PI3K (n=1) inhibitors or double MEK/PI3K inhibition (n=2). Partial responses (PR) were seen in 3 pts (2 with BRAF inhibitor and EGFR inhibitor and 1 with BRAF inhibitor as a single agent). Conclusions: BRAF mt mCRC pts in our institution have a similar pattern to other series reported. Notably, PTEN low expression was present in almost half of the samples analyzed and other co-existent mutations in the ERK and PI3K pathways were detected. This observation, coupled with the clinical outcome observed with single agent BRAF inhibition in this population, suggests that these patients may derive greater benefit from dual BRAF and either EGFR, MEK or PI3K inhibition.

Genomic analyses across six cancer types identify basal-like breast cancer as a unique molecular entity

To improve our understanding of the biological relationships among different types of cancer, we have characterized variation in gene expression patterns in a set of 1,707 samples representing 6 human cancer types (breast, ovarian, brain, colorectal, lung adenocarcinoma and squamous cell lung cancer). In the unified dataset, breast tumors of the Basal-like subtype were found to represent a unique molecular entity as any other cancer type, including the rest of breast tumors, while showing striking similarities with squamous cell lung cancers. Moreover, gene signatures tracking various cancer- and stromal-related biological processes such as proliferation, hypoxia and immune activation were found expressed similarly in different proportions of tumors across the various cancer types. These data suggest that clinical trials focusing on tumors with common profiles and/or biomarker expression rather than their tissue of origin are warranted with a special focus on Basal-like breast cancer and squamous cell lung carcinoma.

mTOR signaling pathway in penile squamous cell carcinoma: pmTOR and peIF4E over expression correlate with aggressive tumor behavior

PURPOSE

Penile squamous cell carcinoma is a rare neoplasm associated with a high risk of metastasis and morbidity. There are limited data on the role of the mTOR signaling pathway in penile squamous cell carcinoma carcinogenesis and tumor maintenance. We assessed a possible role for mTOR signaling pathway activation as a potential predictive biomarker of outcome and a therapeutic target for penile cancer.

MATERIAL AND METHODS

A cohort of 67 patients diagnosed with invasive penile squamous cell carcinoma from 1987 to 2010 who had known HPV status were selected for study. Tissue microarrays were constructed with 67 primary penile squamous cell carcinomas, matched normal tissues and 8 lymph node metastases. Immunohistochemical staining was performed for p53, pmTOR, pERK, p4E-BP1, eIF4E and peIF4E. Expression was evaluated using a semiquantitative H-score on a scale of 0 to 300.

RESULTS

Expression of pmTOR, p4E-BP1, eIF4E and peIF4E was increased in penile tumors compared with matched adjacent normal tissues, indicating activation of the mTOR signaling pathway in penile tumorigenesis. Over expression of pmTOR, peIF4E and p53 was significantly associated with lymph node disease. peIF4E and p53 also correlated with a poor outcome, including recurrence, metastasis or disease specific death. In contrast, pERK and p4E-BP1 were associated with lower pT stages. pmTOR and intense p53 expression was associated with HPV negative tumors.

CONCLUSIONS

Activation of mTOR signaling may contribute to penile squamous cell carcinoma progression and aggressive behavior. Targeting mTOR or its downstream signaling targets, such as peIF4E, may be a valid therapeutic strategy.

Abstract 3034: Determining the profiles and parameters for gene amplification testing of growth factor receptors in lung cancer

Growth factor receptors (GFRs) are amenable to therapeutic intervention in cancer and it is important to select patients appropriately.

One of the mechanisms for activation of GFRs is gene amplification (GA) but discrepancies arising from the difficulties associated with data interpretation and the lack of agreed parameters confound the comparison of results from different laboratories. Here, we attempt to establish appropriate conditions for standardization of the determination of GA in a panel of GFRs. A NSCLC tissue microarray panel containing 302 samples was screened for alterations at ALK,

FGFR1, FGFR2, FGFR3, ERBB2, IGF1R, KIT, MET and PDGFRA by FISH, immunostaining and/or real-time quantitative RT-PCR. Strong amplification was found for FGFR1, ERBB2, KIT/PDFGRA and MET, with frequencies ranging from 1 to

6%. Thresholds for overexpression and GA were established. Strong immunostaining was found in most tumors with ERBB2, MET and KIT amplification, although some tumors underwent strong immunostaining in the absence of GA. KIT and PDFGRA were always co-amplified, but only one tumor showed PDGFRA overexpression, indicating that KIT is the main target.

Amplification of FGFR1 predominated in squamous cell carcinomas, although the association with overexpression was inconclusive. Interestingly, alterations at ALK,

MET, EGFR, ERBB2 and KRAS correlated with augmented levels of phospho-S6 protein, suggesting activation of the mTOR pathway, which may prove useful to pre-select tumors for testing.

Overall, here, we provide with parameters for the determination of GA at ERBB2, MET, KIT, and PDGFRA which could be implemented in the clinic to stratify lung cancer patients for specific treatments.

Citation Format: Eva Pros, Sylvie Lantuejoul, Lydia Sanchez-Verde, Sandra D. Castillo, Ana Suarez-Gauthier, Esther Conde, Juan C. Cigudosa, Fernando Lopez-Rios, Juan Torres-Lanzas, Josep Castellví, Santiago Ramon y Cajal, Elisabeth Brambilla, Montse Sanchez-Cespedes. Determining the profiles and parameters for gene amplification testing of growth factor receptors in lung cancer. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 3034. doi:10.1158/1538-7445.AM2013-3034

Determining the profiles and parameters for gene amplification testing of growth factor receptors in lung cancer

Growth factor receptors (GFRs) are amenable to therapeutic intervention in cancer and it is important to select patients appropriately. One of the mechanisms for activation of GFRs is gene amplification (GA) but discrepancies arising from the difficulties associated with data interpretation and the lack of agreed parameters confound the comparison of results from different laboratories. Here, we attempt to establish appropriate conditions for standardization of the determination of GA in a panel of GFRs. A NSCLC tissue microarray panel containing 302 samples was screened for alterations at ALK, FGFR1, FGFR2, FGFR3, ERBB2, IGF1R, KIT, MET and PDGFRA by FISH, immunostaining and/or real-time quantitative RT-PCR. Strong amplification was found for FGFR1, ERBB2, KIT/PDFGRA and MET, with frequencies ranging from 1 to 6%. Thresholds for overexpression and GA were established. Strong immunostaining was found in most tumors with ERBB2, MET and KIT amplification, although some tumors underwent strong immunostaining in the absence of GA. KIT and PDFGRA were always coamplified, but only one tumor showed PDGFRA overexpression, indicating that KIT is the main target. Amplification of FGFR1 predominated in squamous cell carcinomas, although the association with overexpression was inconclusive. Interestingly, alterations at ALK, MET, EGFR, ERBB2 and KRAS correlated with augmented levels of phospho-S6 protein, suggesting activation of the mTOR pathway, which may prove useful to pre-select tumors for testing. Overall, here, we provide with parameters for the determination of GA at ERBB2, MET, KIT and PDGFRA which could be implemented in the clinic to stratify lung cancer patients for specific treatments.

Fluorescence in situ hybridization and immunohistochemistry as diagnostic methods for ALK positive non-small cell lung cancer patients

Background

Anaplastic Lymphoma Kinase (ALK) positivity represents a novel molecular target in a subset of Non-Small Cell Lung Cancers (NSCLC). We explore Fluorescence in situ Hybridization (FISH) and Immunohistochemistry (IHC) as diagnostic methods for ALK positive patients and to describe its prevalence and outcomes in a population of NSCLC patients.

Methods

NSCLC patients previously screened for Epidermal Growth Factor Receptor (EGFR) at our institution were selected. ALK positive patients were identified by FISH and the value of IHC (D5F3) was explored.

Results

ninety-nine patients were identified. Median age was 61.5 years (range 35–83), all were caucasians, eighty percent were adenocarcinomas, fifty-one percent were male and thirty-eight percent were current smokers. Seven (7.1%) patients were ALK positive by FISH, thirteen (13.1%) were EGFR mutant, and 65 (65.6%) were negative/Wild Type (WT) for both ALK and EGFR. ALK positivity and EGFR mutations were mutually exclusive. ALK positive patients tend to be younger than EGFR mutated or wt patients. ALK positive patients were predominantly never smokers (71.4%) and adenocarcinoma (71.4%). ALK positive and EGFR mutant patients have a better outcome than negative/WT. All patients with ALK FISH negative tumours were negative for ALK IHC. Out of 6 patients positive for ALK FISH with more tissue available, 5 were positive for ALK IHC and 1 negative.

Conclusions

ALK positive patients represent 7.1% of a population of selected NSCLC. ALK positive patients have different clinical features and a better outcome than EGFR WT and ALK negative patients. IHC is a promising method for detecting ALK positive NSCLC patients.

Amplification of fibroblast growth factor receptor type 1 gene (FGFR1) in samples from 101 NSCLC patients (pts) with squamous cell carcinoma (SCC) histology

7041

Background: The FGFR1 gene is located in the chromosomal region 8p12 and encodes a transmembrane receptor tyrosine kinase. Amplification of FGFR1 has been reported in lung cancer, predominantly in SCC (in up to ~ 20%) and has been considered a potential target for treatment with anti-FGFR1 agents. Different methods and cutoff levels to determine FGFR1 amplification have been reported but as yet no consensus has been reached on standard method. The aim of this study is to assess FGFR1 amplification determined by FISH analysis in a set of samples from 101SCC pts and to explore their clinical features. Methods: Tumor samples from 101SCC pts diagnosed at our institution from August 2007 to August 2011 were screened for FGFR1 amplification by FISH using the ZytoLight SPEC FGFR1/CEN8 probe. FGFR1 was considered FISH positive with a ratio > 2.2 and FISH FGFR1 was polysomic with 3 or more signals in ≥30% of tumor cells, any other result was considered as negative. For exploratory analyses FGFR1 amplification was considered positive if a median of 6 or more gene copies were identified and FISH were polysomic with more than 2 gene copies but less than 6. Results: Pts characteristics: median age 76 yrs (range 45-80), 91% male, 33% current smokers, 67% former smokers, stage: 8% IA/ 15% IB/ 11% IIA/ 11% IIB/ 24% IIIA, 12% IIIB/ 19% IV. With a median follow up of 48 months, the median overall survival was 18 months. FISH FGFR1 was positive (ratio > 2.2) in 7 (6.9%) pts: 6 were male, 4 former smokers. FISH FGFR1 was considered negative but polysomic (3 or more signals in ≥30% of tumor cells) in 43/94 (45%) pts. If we use for FISH positivity a cutoff of 6 or more copies only 3 patients were considered as positive for FGFR1 amplification (2 were also FISH positive by ratio>2.2). All those 5 patients considered FISH negative by gen copy number (but positive by ratio) were polysomic. Conclusions: In our experience FGFR1 amplification detected by FISH isrelatively uncommon in SCC, although a relevant proportion of FGFR1 FISH negative tumors had polysomy. Standarization of methods to determine FGFR1 amplification and the potential clinical significance of the presence of FGFR1 polysomy are needed.

Prognostic significance of PI3K pathway (PI3Kp) dysregulation in metastatic breast cancer (MBC) patients (pts)

566

Background: PI3Kp dysregulation represents a potential target for therapies that are currently being tested in clinical trials. This observational retrospective study aims to evaluate the prognostic implications of PI3Kp dysregulation in MBC. Methods: MBC pts with PI3Kp status assessment from Sep09 to Sep11 were reviewed. PIK3CA mutation status analyzed in paraffin-embedded tissue by DxS PI3K Mutation Test Kit or Sequenom MassARRAY. PTEN status determined by IHC. PI3Kp status: (a) No dysregulation: PIK3CA wt and PTEN normal; (b) PI3Kp dysregulation: PIK3CA mutation (PIK3CAmut) or PTEN low (HScore≤50). Results: 232 MBC pts screened, median age 49.8 (22.9-83.1) and median MBC lines 4 (1-15). Distribution: HR+/HER2- 99 (43%), HER2+ 52 (22%), triple negative 35 (15%), unclassified 46 (20%). Sites of metastasis: visceral 173 (75%), only skin 10 (4%), only bone 49 (21%). PIK3CA status assessed in 174 pts, 53 (22.8%) bearing a mutation (21 exon9, 32 exon20). PTEN status assessed in 229 pts, PTEN low 61 (26.6%). PI3Kp dysregulation in 103/185 pts (55.6%). Time to progression to first line MBC treatment (TTP) and overall survival after MBC diagnosis (OS) are shown. Disease free survival (DFS) and distant-disease free survival (DDFS) in pts initially diagnosed with early breast cancer (n=193) has also been calculated. Conclusions: These results suggest that PI3Kp dysregulation, either by PIK3CA mutation or PTEN low, does not seem to have impact on disease recurrence, response to first line MBC treatment or overall MBC survival.[Table: see text]

Molecular profiling of patients (pts) with colorectal cancer (CRC) and matched targeted therapy (MTA) in phase I clinical trials

3014

Background: Molecular prescreening and biomarker enrichment strategies in Phase 1 trials with targeted therapies are anticipated to improve the outcomes of affected pts. Methods: As part of our personalized oncology program, tumors from pts with advanced chemorefractory CRC were analyzed for specific molecular aberrations (KRAS/ BRAF/ PIK3CA mutations [mut], PTEN and pMET expression) at the Vall d'Hebron Molecular Pathology and Genomics Labs. Those whose tumors were found to have a dysregulation were offered a Phase 1 trial with MTA. Results: During 2010 and 2011, tumor molecular analysis was performed in 254 pts: KRAS mut (80/254, 31.5%), BRAF mut (24/196, 12.2%), PIK3CA mut (15/114, 13.2%), KRAS+PIK3CA mut (9/114, 7.9%), PTEN low (97/183, 53.0% - HSCORE<50; 45/183, 24.6% - PTEN null), KRAS mut + PTEN low (38/138, 20.8%), pMET high (38/64, 59.4% with HSCORE>30). In total, 68 pts (median, age 63 yrs; prior therapies 3), received 82 different matched therapies. Type of MTA: PI3K pathway inh (if PIK3CA mut, n=10; or PTEN low, n=32), MEK+PI3K pathway inh (if KRAS mut, n=10; or BRAF mut, n=1), second-generation anti-EGFR mAbs (if KRAS wild-type, n=11), anti-HGF mAb (if pMET high, n=10), mTOR inh + anti-IGFR-1R mAb (if PTEN low, n=5) and BRAF inh (if BRAF mut, n=3). Median time to treatment failure (TTF) with MTA was 7.9 weeks (CI95%:7.6-8.1) vs. 16.3 weeks (CI95%:13.9-18.7) for their prior systemic antitumor therapy (p<0.001). If prior therapy non-standard (according to NCCN guidelines, n=39), TTF with MTA 7.9 weeks (CI95%:6.8-8.9) vs. TTF with prior therapy 8.7 weeks (CI95%:7.3-10.1). If an approved standard regimen (n=43), TTF with MTA 7.9 weeks (CI95%:7.6-8.1) vs. TTF with prior therapy 21.9 weeks (CI95%:15.0-28.7). Partial response was seen in one pt (1.2%, PI3K inh with PIK3CA mut) and stable disease > 16 weeks in 10 cases (12.2%). Clinical benefit, defined as a TTF ratio ≥ 1.3 (TTF on MTA/ TTF on prior therapy), was seen with 15.9% of the therapies (13/82). Conclusions: Preliminary results suggest that matching chemorefractory CRC patients with targeted agents in early clinical trials based on the current molecular profile does not result in longer TTF compared to their prior therapy.

Abstract 683: Evaluation of PTEN and PIK3CA status in breast cancer for patient selection: Cross-validation between institutions

PTEN and PIK3CA status are potential predictors of response to PI3K-pathway inhibitors. Therefore, we searched the most reliable platform to assess both PTEN expression and PIK3CA mutations in primary and metastatic breast cancer (BC). Cross-validation across platforms at SU2C sites was performed using three different sample sets: 18 formalin-fixed paraffin-embedded (FFPE) primary triple negative breast cancer (pTNBC) samples from VHUH/VHIO, 12 FFPE pTNBC samples from Columbia University and 21 FFPE all-comers BC from VHUH/VHIO. Moreover, we evaluated the transitions occurring between early and disseminated disease in 14 paired FFPE samples from VHUH/VHIO. PTEN alterations were genotyped in 18 triple pTNBCs by OncoscanTM platform (Affymetrix) and were correlated to immunohistochemistry (IHC, 138G6 CST antibody). PTEN loss of heterozygosity (LOH, n=4) or frameshift mutation (n=1) was concordant to PTEN protein loss (H-Score&lt;50) by IHC in 4 samples; with the discordant LOH having an H-Score of 60. In the other two non-concordant samples (total of 3/18, 17% discordance), presence of non-tumor DNA, as assessed by genomic heterogeneity, impeded an accurate DNA copy number variation determination by OncoscanTM. PTEN protein loss by IHC was also cross-validated between two institutions (Columbia and VHIO). In a cohort of 12 pTNBCs containing eight PTEN low samples, only two samples were discordant (2/12, 17% discordance). Paired primary versus metastatic tumors were identified to transit either way, in the PTEN assessment by IHC (2/8 paired samples, 25% transition). PTEN IHC failed in most (3/5) metastatic bone samples due to Bouin's fixative required for handling of this tissue. PIK3CA mutations by OncoscanTM were concordant to MassARRAY (Sequenom) in 4 out of 5 mutated samples within the panel of 18 pTNBCs. The discrepancy (1/18, 6%) was most likely due to differences in the sensitivity of the two assays. In another cohort of 21 BC samples, PIK3CA mutational status was cross-validated by MassARRAY at two institutions (MDACC and VHIO). Using identical, customized panels we found that only two samples were discordant because of mutant allele frequency close to the sensitivity of the assay (10%). Manual review of the individual assays increased the concordance to 100%. Among 14 paired primary vs metastatic breast cancers we detected two transitions from wild type (WT) to H1047R mutation and one transition from E545K to WT (3/14, 21% transition), underscoring the need to determine PIK3CA status in metastatic lesions. The divergence evaluating both PTEN and PIK3CA status between institutions was due to cut-off and sensitivity of the assays respectively. For patient pre-screening purposes, MassARRAY and IHC can be performed at each SU2C site both in primary and metastatic breast cancer lesions. OncoscanTM is a valid, centralized platform for evaluation of PTEN and PIK3CA genomic alterations in BC.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 683. doi:1538-7445.AM2012-683

Abstract 4984: Phosporylation of eIF4E confer resistance to cellular stress

Eukaryotic initiation factor (eIF) 4E mediates eIF4F association with the mRNA 5′ cap structure and is an essential factor for canonical protein translation. eIF4E can act as an oncogene when overexpressed in cell lines and high levels of eIF4E and phosporylated peIF4E have been described in a large number of human tumors. eIF4E has also been described as a component of cytoplasmic stress granules and processing bodies. Importantly, non-phosphorylated 4E-BP1 (often in response to stress) binds eIF4E to suppress protein translation. We demonstrated previously that high levels of peIF4E were associated with resistance to this suppressor effect in carcinoma cell lines. Because the role of peIF4E is not yet well established, we evaluated the role of eIF4E phosphorylation on in vitro stress resistance. Breast carcinoma cell lines (MDA-MB 231, MBA- MB 468 and HeLa cells) and an immortalized human keratinocyte cell line (HaCaT) were infected with retrovirus expressing wild type, hyperphosporylated (S209D) or hypophosporylated (S209D) mutants of eIF4E. Cells were subjected to different types of stress including oxidative (Arsenite), nutrient starving and cisplatin treatment. Immediate and long term response to stress was evaluated using colony formation, MTT cell proliferation assays, co-inmunoprecipitation and immunofluorescence microscopy. A significantly greater recovery after all forms of stress was observed in all the cell lines expressing hyperphosporylated eIF4E-S209D. After treatment with arsenite there was an increase of peIF4E, 4E-T and Hur and importantly higher increase of levels of Hur, CyclinD1, Mcl-1 and eIF4G in eIF4E-S209D expressing cells. Under normal condition we observed a unique colocalitzation of 4E-T and eIF4E-S209D in cytoplasmic bodies. This complex colocalize with Ago2 but not with markers of the stress granules (TIA-1) and processing bodies (DCP1A). By co-immunopreciptation, we observed that peIF4E binds to its carrier protein 4E-T, Ago2 and Hur. Conclusions: Phosphorylated eIF4E confer resistance to several stress conditions, including oxidative stress, DNA damage and nutrient deprivation. The fact that there was a relevant and significant increase of proteins such as Cyclin D1, Mcl-1 and Hur suggests that phosporylated eIF4E has an important role in selectively stimulating RNA translation under stress conditions, possibly via the formation of a unique type of 4E-T/peIF4E cytoplasmic bodies.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 4984. doi:1538-7445.AM2012-4984

Balance between MKK6 and MKK3 mediates p38 MAPK associated resistance to cisplatin in NSCLC

The p38 MAPK signaling pathway has been proposed as a critical mediator of the therapeutic effect of several antitumor agents, including cisplatin. Here, we found that sensitivity to cisplatin, in a system of 7 non-small cell lung carcinoma derived cell lines, correlated with high levels of MKK6 and marked activation of p38 MAPK. However, knockdown of MKK6 modified neither the response to cisplatin nor the activation of p38 MAPK. Deeper studies showed that resistant cell lines also displayed higher basal levels of MKK3. Interestingly, MKK3 knockdown significantly decreased p38 phosphorylation upon cisplatin exposure and consequently reduced the response to the drug. Indeed, cisplatin poorly activated MKK3 in resistant cells, while in sensitive cell lines MKK3 showed the opposite pattern in response to the drug. Our data also demonstrate that the low levels of MKK6 expressed in resistant cell lines are the consequence of high basal activity of p38 MAPK mediated by the elevated levels of MKK3. This finding supports the existence of a regulatory mechanism between both MAPK kinases through their MAPK. Furthermore, our results were also mirrored in head and neck carcinoma derived cell lines, suggesting our observations boast a potential universal characteristic in cancer resistance of cisplatin. Altogether, our work provides evidence that MKK3 is the major determinant of p38 MAPK activation in response to cisplatin and, hence, the resistance associated with this MAPK. Therefore, these data suggest that the balance between both MKK3 and MKK6 could be a novel mechanism which explains the cellular response to cisplatin.

Spinophilin acts as a tumor suppressor by regulating Rb phosphorylation

The scaffold protein Spinophilin (SPN) is a regulatory subunit of phosphatase1a located at 17q21.33. This region is frequently associated with microsatellite instability and LOH containing a relatively high density of known tumor suppressor genes, including BRCA1. Several linkage studies have suggested the existence of an unknown tumor suppressor gene distal to BRCA1. Spn may be this gene, but the mechanism through which this gene makes its contribution to cancer has not been described. In this study, we aimed to determine how loss of Spn may contribute to tumorigenesis. We explored the contribution of SPN to PP1a-mediated Rb regulation. We found that the loss of Spn downregulated PPP1CA and PP1a activity, resulting in a high level of phosphorylated Rb and increased ARF and p53 activity. However, in the absence of p53, reduced levels of SPN enhanced the tumorigenic potential of the cells. Furthermore, the ectopic expression of SPN in human tumor cells greatly reduced cell growth. Taken together, our results demonstrate that the loss of Spn induces a proliferative response by increasing Rb phosphorylation, which, in turn, activates p53, thereby neutralizing the proliferative response. We suggest that Spn may be the tumor suppressor gene located at 17q21.33 acting through Rb regulation.

Down-regulation of spinophilin in lung tumours contributes to tumourigenesis

The scaffold protein spinophilin (Spn, PPP1R9B) is one of the regulatory subunits of phosphatase-1a (PP1), targeting it to distinct subcellular locations and to its target. Loss of Spn reduces PPP1CA levels, thereby maintaining higher levels of phosphorylated pRb. This effect contributes to an increase in p53 activity. However, in the absence of p53, reduced levels of Spn increase the tumourigenic properties of cells. In addition, Spn knockout mice have a reduced lifespan, an increased number of tumours and increased cellular proliferation in some tissues, such as the mammary ducts. In addition, the combined loss of Spn and p53 activity leads to an increase in mammary carcinomas, confirming the functional relationship between p53 and Spn. In this paper, we report that Spn is absent in 20% and reduced in another 37% of human lung tumours. Spn reduction correlates with malignant grade. Furthermore, the loss of Spn also correlates with p53 mutations. Analysis of miRNAs in a series of lung tumours showed that miRNA106a* targeting Spn is over-expressed in some patients, correlating with decreased Spn levels. Proof-of-concept experiments over-expressing miRNA106a* or Spn shRNA in lung tumour cells showed increased tumourigenicity. In conclusion, our data showed that miRNA106a* over-expression found in lung tumours might contribute to tumourigenesis through Spn down-regulation in the absence of p53.

Detection of EGFR mutations with mutation-specific antibodies in stage IV non-small-cell lung cancer

Background

Immunohistochemistry (IHC) with mutation-specific antibodies may be an ancillary method of detecting EGFR mutations in lung cancer patients.

Methods

EGFR mutation status was analyzed by DNA assays, and compared with IHC results in five non-small-cell lung cancer (NSCLC) cell lines and tumor samples from 78 stage IV NSCLC patients.

Results

IHC correctly identified del 19 in the H1650 and PC9 cell lines, L858R in H1975, and wild-type EGFR in H460 and A549, as well as wild-type EGFR in tumor samples from 22 patients. IHC with the mAb against EGFR with del 19 was highly positive for the protein in all 17 patients with a 15-bp (ELREA) deletion in exon 19, whereas in patients with other deletions, IHC was weakly positive in 3 cases and negative in 9 cases. IHC with the mAb against the L858R mutation showed high positivity for the protein in 25/27 (93%) patients with exon 21 EGFR mutations (all with L858R) but did not identify the L861Q mutation in the remaining two patients.

Conclusions

IHC with mutation-specific mAbs against EGFR is a promising method for detecting EGFR mutations in NSCLC patients. However these mAbs should be validated with additional studies to clarify their possible role in routine clinical practice for screening EGFR mutations in NSCLC patients.

Abstract 5756: The receptor tyrosine kinase EPHB4 has tumor suppressor activities in intestinal tumorigenesis

Colorectal cancer is the second cause of cancer related death in the western world and although the genetic and molecular mechanisms involved in initiation and progression of these tumors is among the best characterized, there are significant gaps in our understanding of this disease. The family of receptor tyrosine kinases EPH and their Ephrin ligands regulate cell proliferation, migration and attachment. An important role in colorectal carcinogenesis is emerging for some of its members. In this study we used animal models and analysis of large tumor collections to investigate the possible role of EPHB4 as a new tumor suppressor gene in colorectal cancer. Modulation of EPHB4 levels in colon cancer cell lines resulted in significant growth differences in vitro and in a xenograft model, with low levels of EPHB4 associated with faster growth. In addition, using a genetic model of intestinal tumorigenesis where Apc mutations lead to initiation of the tumorigenic process (Apcmin mice), we show that inactivation of a single allele of EphB4 results in: a) higher proliferation both in the normal epithelium and intestinal tumors, b) significantly larger tumors in the small intestine and c) a 10-fold increase in the number of tumors in the large intestine. This was associated with a 25% reduction in the lifespan of Apcmin mice (p&lt;0.0001). Gene expression analysis demonstrated that EphB4 inactivation causes a profound transcriptional reprogramming affecting genes involved in cell proliferation, remodeling of the extracellular matrix and cell attachment to the basement membrane, among other functional groups of genes. Importantly, in agreement with the expression profiling experiments, using an in vitro assay we demonstrate that loss of EPHB4 in colon cancer cells results in a significantly increased potential to invade through a complex extracellular matrix. In addition, using archived human colorectal tumors we investigated the possible association between EPHB4 levels and patient prognosis. In a series of 252 cases, we found that EPHB4 expression is frequently reduced or lost in colorectal tumors. Patients with low EPHB4 tumor levels had significantly shorter survival than patients in the high EPHB4 group (Logrank test p&lt;0.01; median survival of 1.8 and over 9 years, respectively). Moreover, we demonstrate that EPHB4 promoter hypermethylation is a common mechanism of EPHB4 inactivation. Collectively, these results indicate that EPHB4 has tumor suppressor activities in colorectal cancer and that tumor expression of this tyrosine kinase can be used to predict patient prognosis.

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 5756.

Subtractive proteomic approach to the endometrial carcinoma invasion front

Tumor invasion defines the transition between tissue-restricted carcinomas, related to good outcome as optimal surgery becomes possible, and metastatic tumors associated with poor prognosis and a dramatic decrease in survival. In endometrial cancer, myometrial infiltration represents a determinant parameter highly valuable in prognosis. To date, the identification of proteins involved in endometrial carcinoma invasion has been essentially conducted by immunohistochemical methods, without a global perception on the invasive front. Laser microdissection presents nowadays limitations to the profound spatiotemporal regulation from both the tumor and the surrounding stroma occurring at the invasive front. In this work, we attempted an alternative proteomic approach to characterize specific components of the tumor invasive front or its reactive stroma, by comparing the invasive area of an endometrial carcinoma with the noninvasive superficial tumor area and normal tissue from the same patients. This strategy led us to identify proteins involved in cellular morphology, assembly and movement, differentially expressed at the invasive front, as well as pathways like cell-to-cell signaling and interaction and a modulated response to oxidative stress as events related to endometrial carcinoma invasion. In conclusion, we could identify new players of myometrial infiltration by applying a subtractive proteomic approach to the endometrial carcinoma invasion front.

The receptor tyrosine kinase EPHB4 has tumor suppressor activities in intestinal tumorigenesis

Colorectal cancer is the second cause of cancer-related death in the western world, and although the genetic and molecular mechanisms involved in the initiation and progression of these tumors are among the best characterized, there are significant gaps in our understanding of this disease. The role of EPHB signaling in colorectal cancer has only recently been realized. Here, we use animal models to investigate the role of EphB4 in intestinal tumorigenesis. Modulation of EPHB4 levels in colon cancer cell lines resulted in significant differences in tumor growth in a xenograft model, with low levels of EPHB4 associated with faster growth. In addition, using a genetic model of intestinal tumorigenesis where adenomatous polyposis coli (Apc) mutations lead to initiation of the tumorigenic process (Apc(min) mice), we show that inactivation of a single allele of EphB4 results in higher proliferation in both the normal epithelium and intestinal tumors, significantly larger tumors in the small intestine, and a 10-fold increase in the number of tumors in the large intestine. This was associated with a 25% reduction in the lifespan of Apc(min) mice (P < 0.0001). Gene expression analysis showed that EphB4 mutations result in a profound transcriptional reprogramming, affecting genes involved in cell proliferation, remodeling of the extracellular matrix, and cell attachment to the basement membrane among other functional groups of genes. Importantly, in agreement with the expression profiling experiments, using an in vitro assay, we show that loss of EPHB4 in colon cancer cells results in a significantly increased potential to invade through a complex extracellular matrix. Collectively, these results indicate that EphB4 has tumor suppressor activities and that regulation of cell proliferation, extracellular matrix remodeling, and invasive potential are important mechanisms of tumor suppression.

Regulation of replicative and stress-induced senescence by RSK4, which is down-regulated in human tumors

PURPOSE

The control of senescence and its biochemical pathways is a crucial factor for understanding cell transformation. In a large RNA interference screen, the RSK4 gene was found to be related to p53-dependent arrest. The purpose of the present study was to investigate the potential role of RSK4 as a tumor suppressor gene.

EXPERIMENTAL DESIGN

RSK4 expression was determined by quantitative real-time PCR and immunoblot in 30 colon and 20 renal carcinomas, and in 7 colon adenomas. Two HCT116 colon carcinoma cell lines (p53 wt and p53 null), IMR90 human fibroblasts, and E1A-expressing IMR90 cells were infected with RSK4 cDNA and/or shRNA. RSK4 expression levels were analyzed in HCT116 p53 wt or p53 null and IMR90 after senescence induction by quantitative real-time PCR and Western blot.

RESULTS

The RSK4 gene was down-regulated in 27 of 30 colon carcinomas (P < 0.001), 16 of 20 renal cell carcinomas (P < 0.01), and 6 of 7 colon adenomas (P < 0.01). In vitro overexpression of RSK4 induced cell arrest and senescence features in normal fibroblasts and malignant colon carcinoma cell lines. Interestingly, in these cell lines RSK4 mRNA levels were increased both in replicative and stress-induced senescence. Moreover, IMR90 partially immortalized by RSK4 shRNA and HCT116 with this short hairpin RNA were more resistant to cisplatin treatment. Finally, cells expressing E1A or Rb short interfering RNA were resistant to RSK4-mediated senescence.

CONCLUSION

These results support the concept that RSK4 may be an important tumor suppressor gene by modulating senescence induction and contributing to cell proliferation control in colon carcinogenesis and renal cell carcinomas.

Cell signaling in endometrial carcinoma: phosphorylated 4E-binding protein-1 expression in endometrial cancer correlates with aggressive tumors and prognosis

In the oncogenic process, cell growth control plays a crucial role, and growth factor receptors and their signaling pathways are known to be altered in endometrial cancer, mostly in type I carcinomas. Two main pathways are involved in transmitting the proliferative signal from the membrane receptors to the nucleus: phosphatydil-inositol-3-kinase-protein kinase B-mammalian target of rapamycin and RAS-RAF-ERK pathways. A final effector of these signaling cascades is the cap-dependent mRNA translation initiation complex, which is negatively regulated by 4E-BP1. The aim of our work was to study the relative importance of the factors involved in these pathways and to see their correlation with the clinicopathologic features of the tumors and their prognosis. We studied 120 endometrial carcinomas, including 93 type I and 27 type II carcinomas, and 18 control cases. Tissue microarrays were constructed and immunohistochemistry was performed for HER2, p53, and the phosphorylated forms of protein kinase B, extracellular signal-regulated kinase, and 4E-BP1. HER2 was overexpressed in 11% of carcinomas but not in control cases, and 30% of carcinomas showed activation of protein kinase B and extracellular signal-regulated kinase, mostly in type II carcinomas. The phosphorylated form of 4E-BP1 was found to be cytoplasmic in 31% of cases, and in 63% of cases it showed nuclear expression; the latter was only found in carcinomas. p53 positivity was found in type II and in grade 3 type I carcinomas. This nuclear expression of phospho-4E-BP1 and HER2 overexpression were the only characteristics with prognostic significance. The activation of the signaling pathways that control cell growth is a common event in endometrial carcinomas. 4E-BP1 is a downstream effector of these pathways whose activation status correlates with aggressive phenotypes and prognosis. This factor can reflect the activity of these pathways, regardless of the upstream molecular alterations, and, therefore, it can be a hallmark of the transmission of the oncogenic signal to the nucleus.

Translational research in glioblastoma multiforme: molecular criteria for patient selection

In spite of the dismal outcome of glioblastoma multiforme (GBM), we are in a position to provide a ray of hope to patients and families. Methylation of MGMT in tumor occurs in approximately a third of patients and predicts meaningful response and survival to adjuvant radiotherapy plus temozolomide. Limited access to tumor tissue in some patients could be circumvented by examining MGMT methylation in circulating serum DNA, although this approach needs to be validated. Molecular signatures are also promising prognostic and predictive markers, and clinical trials should be carried out to validate their use in the selection of patients for specific targeted therapies. Gene expression by quantitative PCR of key components of these molecular signatures could pave the way for easy identification of different subgroups of patients. Translational clinical trials are warranted in order to detect the subgroups of patients resistant to radiotherapy who may derive benefit from novel therapies, including antiangiogenic drugs.

Dose- and schedule-dependent inhibition of the mammalian target of rapamycin pathway with everolimus: a phase I tumor pharmacodynamic study in patients with advanced solid tumors

PURPOSE

Everolimus is a selective mammalian target of rapamycin (mTOR) inhibitor with promising anticancer activity. In order to identify a rationally based dose and schedule for cancer treatment, we have conducted a tumor pharmacodynamic phase I study in patients with advanced solid tumors.

PATIENTS AND METHODS

Fifty-five patients were treated with everolimus in cohorts of 20, 50, and 70 mg weekly or 5 and 10 mg daily. Dose escalation depended on dose limiting toxicity (DLT) rate during the first 4-week period. Pre- and on-treatment steady-state tumor and skin biopsies were evaluated for total and phosphorylated (p) protein S6 kinase 1, eukaryotic initiation factor 4E (elF-4E) binding protein 1 (4E-BP1), eukaryotic initiation factor 4G (eIF-4G), AKT, and Ki-67 expression. Plasma trough levels of everolimus were determined on a weekly basis before dosing during the first 4 weeks.

RESULTS

We observed a dose- and schedule-dependent inhibition of the mTOR pathway with a near complete inhibition of pS6 and peIF-4G at 10 mg/d and >or= 50 mg/wk. In addition, pAKT was upregulated in 50% of the treated tumors. In the daily schedule, there was a correlation between everolimus plasma trough concentrations and inhibition of peIF4G and p4E-BP1. There was good concordance of mTOR pathway inhibition between skin and tumor. Clinical benefit was observed in four patients including one patient with advanced colorectal cancer achieving a partial response. DLTs occurred in five patients: one patient at 10 mg/d (grade 3 stomatitis) and four patients at 70 mg/wk (two with grade 3 stomatitis, one with grade 3 neutropenia, and one with grade 3 hyperglycemia).

CONCLUSION

Everolimus achieved mTOR signaling inhibition at doses below the DLT. A dosage of 10 mg/d or 50 mg/wk is recommended for further development.

Expression of p21cip1, p27kip1, and p16INk4a cyclin-dependent kinase inhibitors in papillary thyroid carcinoma: correlation with clinicopathological factors

In a variety of human malignancies, aberrant expression of proteins involved in the control of cell-cycle progression has been reported. In this study, p21cip1, p27kip1, and p16INk4a cyclin-dependent kinase inhibitors were analyzed to evaluate their usefulness in clinical management of papillary thyroid carcinoma (PTC). Archived material derived from 46 cases of PTC was analyzed immunohistochemically. Protein expression was ascertained on tissue microarrays, and results were correlated with clinicopathological features of the patients. Positive immunostaining was observed in 14 (30,4%) p21cip1, 26 (56,5%) p27kip1, and 14 (30,4%) p16INk4a cases. No significant correlation between p21cip1 or p27kip1 and clinical factors was found. In contrast, p16INk4a expression showed a significant correlation with initial extension of the disease. Therefore, 45.8% of patients with loco-regional extension were p16INk4a positive, whereas overexpression was only seen in 15.7% of cases with intrathyroid disease (p < 0.05). Moreover, all patients with simultaneous p16INk4a positivity and lack of p27kip1 staining (four patients) presented lymph node metastases. In contrast, only 12 (28.5%) of the remaining patients showed lymph node tumor involvement. In conclusion, p16INk4a expression suggests extrathyroid neck extension of PTC. This effect is enhanced when p27kip1 is negative. We think that their analysis by immunohistochemistry could be useful in the management of patients with PTC.

Prognostic significance of vascular endothelial growth factor and cyclooxygenase-2 in patients with rectal cancer treated with preoperative radiotherapy

PURPOSE

To analyze the prognostic value of cyclooxygenase-2 (COX-2) and vascular endothelial growth factor (VEGF) in patients with locally advanced rectal cancer treated with preoperative radiotherapy.

METHODS

Eighty-one patients with locally advanced rectal cancer were studied. All patients received preoperative pelvic radiotherapy. Forty-seven patients received concomitant chemotherapy. Surgical resection was performed 4-8 weeks later in all patients. Immunohistochemical examination of COX-2 and VEGF was performed on the preirradiation diagnostic biopsies. An immunohistochemical score established from the extension and intensity of the markers was used for analysis. The log-rank test and proportional hazards regression analysis were used to calculate the probability that the biomarkers were associated with patient outcome.

RESULTS

COX-2 expression was positive in 38 tumors (51%) while VEGF expression was positive in 43 (57%). The only clinicopathological parameter significantly associated with COX-2 or VEGF expression was performance status. None of the 2 markers were found to predict treatment response. There was no statistically significant correlation between COX-2 and VEGF. Univariate analysis identified pathological stage (pT, pN) as prognostic for disease-free survival. When VEGF expression was analyzed, disease-free survival was reduced among patients with VEGF-positive tumors (p = 0.047). This was specifically related to metastases-free survival (p = 0.016). These results were not observed for COX-2. After multivariate analysis, the pT and pN stage remained as independent prognostic factors.

CONCLUSIONS

VEGF-positive expression is an indicator of poor disease-free survival, specifically linked to distant metastasis. More aggressive treatment strategies are warranted in pT3-4 and pN1-2 rectal cancer patients.

Expression of p95HER2, a truncated form of the HER2 receptor, and response to anti-HER2 therapies in breast cancer

BACKGROUND

Women with HER2-overexpressing breast cancers have poor prognosis, and many are resistant to the HER2 monoclonal antibody trastuzumab. A subgroup of HER2-overexpressing tumors also express p95HER2, an amino terminally truncated receptor that has kinase activity. Because p95HER2 cannot bind to trastuzumab but should be responsive to the HER2 tyrosine kinase inhibitor lapatinib, we compared the sensitivity of tumors expressing p95HER2 and tumors expressing the full-length HER2 receptor to these agents.

METHODS

MCF-7 and T47D breast cancer cells were stably transfected with either full-length HER2 or p95HER2. We studied the effects of trastuzumab and lapatinib on receptor signaling, cell proliferation, and the growth of xenograft tumors. A paraffin-based immunofluorescence assay was developed to study the association between p95HER2 expression and sensitivity to trastuzumab in patients with advanced breast cancer. All statistical tests were two-sided.

RESULTS

Treatment of p95HER2-expressing cells with lapatinib inhibited p95HER2 phosphorylation, reduced downstream phosphorylation of Akt and mitogen-activated protein kinases, inhibited cell growth (MCF-7p95HER2 clones, lapatinib versus control, mean growth inhibition = 57.6% versus 22.6%, difference = 35%, 95% confidence interval [CI] = 22.5% to 47.3%; P<.001; T47Dp95HER2 clones, lapatinib versus control, mean growth inhibition = 36.8% versus 20%, difference = 16.8%, 95% CI = 11.3% to 22.3%, P<.001), and inhibited growth of MCF-7p95HER2 xenograft tumors (lapatinib versus control, mean = 288.8 versus 435 mm3, difference = 146.2 mm3, CI = 73.8 to 218.5 mm3, P = .002). By contrast, treatment with trastuzumab had no effect on any of these parameters. Of 46 patients with metastatic breast cancer who were treated with trastuzumab, only one of nine patients (11.1%) expressing p95HER2 responded to trastuzumab (with a partial response), whereas 19 of the 37 patients (51.4%) with tumors expressing full-length HER2 achieved either a complete (five patients) or a partial (14 patients) response (P = .029).

CONCLUSIONS

Breast tumors that express p95HER2 are resistant to trastuzumab and may require alternative or additional anti-HER2-targeting strategies.

4E-binding protein 1, a cell signaling hallmark in breast cancer that correlates with pathologic grade and prognosis

PURPOSE

Cell signaling pathways include a complex myriad of interconnected factors from the membrane to the nucleus, such as erbB family receptors and the phosphoinositide-3-kinase/Akt/mTOR and Ras-Raf-ERK cascades, which drive proliferative signals, promote survival, and regulate protein synthesis.

EXPERIMENTAL DESIGN

To find pivotal factors in these pathways, which provide prognostic information in malignancies, we studied 103 human breast tumors with an immunohistochemical profile, including total and phosphorylated (p) proteins: human epidermal growth factor receptor 2 (HER2), epidermal growth factor receptor, extracellular signal-regulated kinase 1/2, Akt, 4E-binding protein 1 (4EBP1), eukaryotic initiation factor 4E, phosphorylated ribosomal protein S6 kinase 1, phosphorylated ribosomal protein S6, and Ki67. Western blot and reverse lysate protein arrays were also done in a subset of tumors.

RESULTS

Significantly, activation of the phosphoinositide-3-kinase/Akt/mTOR cascade was detected in a high proportion of tumors (41.9%). Tumors with HER2 overexpression showed higher p-Akt as compared with negative tumors (P < 0.001). Levels of p-Akt correlated with the downstream molecules, p-4EBP1 (P = 0.001) and p-p70S6K (P = 0.05). Although 81.5% of tumors expressed p-4EBP1, in 16.3% of these tumors, concomitant activation of the upstream factors was not detected. Interestingly, p-4EBP1 was mainly expressed in poorly differentiated tumors (P < 0.001) and correlated with tumor size (P < 0.001), presence of lymph node metastasis (P = 0.002), and locoregional recurrences (P = 0.002). Coexpression of p-4EBP1 and p-eIF4G correlated with a high tumor proliferation rate (P = 0.012).

CONCLUSION

In this study, p-4EBP1 was the main factor in signaling pathways that associate with prognosis and grade of malignancy in breast tumors. Moreover, p-4EBP1 was detected in both HER2-positive and HER2-negative tumors. This factor seems to be a channeling point at which different upstream oncogenic alterations converge and transmit their proliferative signal, modulating protein translation.

MAP17 enhances the malignant behavior of tumor cells through ROS increase

Tumorigenesis occurs when the mechanisms involved in the control of tissue homeostasis are disrupted and cells stop responding to physiological signals. Therefore, genes capable of desensitizing tumoral cells from physiological signals may provide a selective advantage within the tumoral mass and influence the outcome of the disease. We undertook a large-scale genetic screen to identify genes able to alter the cellular response to physiological signals and provide selective advantage once tumorigenesis has begun. We identified MAP17, a small 17 kDa non-glycosylated membrane protein previously identified by differential display being over-expressed in carcinomas. Tumor cells that over-express MAP17 show an increased tumoral phenotype with enhanced proliferative capabilities both in presence or absence of contact inhibition, decreased apoptotic sensitivity and increased migration. MAP17-expressing clones also grow better in nude mice. The increased malignant cell behavior induced by MAP17 are associated with an increase in reactive oxygen species (ROS) production, and the treatment of MAP17-expressing cells with antioxidants results in a reduction in the tumorigenic properties of these cells. Treatment of melanoma cells with inhibitors of Na+-coupled co-transporters lead to an inhibition of ROS increase and a decrease in the malignant cell behavior in MAP17-expressing clones. Finally, we show that MAP17-dependent ROS increase and tumorigenesis are dependent on its PDZ-binding domain, since disruption of its sequence by point mutations abolishes its ability to enhance ROS production and tumorigenesis. Our work shows the tumorigenic capability of MAP17 through a connection between Na+-coupled co-transporters and ROS.

Phosphorylated 4E binding protein 1: a hallmark of cell signaling that correlates with survival in ovarian cancer

BACKGROUND

Growth factor receptors and cell signaling factors play a crucial role in human carcinomas and have been studied in ovarian tumors with varying results. Cell signaling involves multiple pathways and a myriad of factors that can be mutated or amplified. Cell signaling is driven through the mammalian target of rapamycin (mTOR) and extracellular regulated kinase (ERK) pathways and by some downstream molecules, such as 4E binding protein 1 (4EBP1), eukaryotic initiation factor 4E, and p70 ribosomal protein S6 kinase (p70S6K). The objectives of this study were to analyze the real role that these pathways play in ovarian cancer, to correlate them with clinicopathologic characteristics, and to identify the factors that transmit individual proliferation signals and are associated with pathologic grade and prognosis, regardless specific oncogenic alterations upstream.

METHODS

One hundred twenty-nine ovarian epithelial tumors were studied, including 20 serous cystadenomas, 7 mucinous cystadenomas, 11 serous borderline tumors, 16 mucinous borderline tumors, 29 serous carcinomas, 16 endometrioid carcinomas, 15 clear cell carcinomas, and 15 mucinous carcinomas. Tissue microarrays were constructed, and immunohistochemistry for the receptors epidermal growth factor receptor (EGFR) and c-erb-B2 was performed and with phosphorylated antibodies for protein kinase B (AKT), 4EBP1, p70S6K, S6, and ERK.

RESULTS

Among 129 ovarian neoplasms, 17.8% were positive for c-erb-B2, 9.3% were positive for EGFR, 47.3% were positive for phosphorylated AKT (p-AKT), 58.9% were positive for p-ERK, 41.1% were positive for p-4EBP1, 26.4% were positive for p70S6K, and 15.5% were positive for p-S6. Although EGFR, p-AKT, and p-ERK expression did not differ between benign, borderline, or malignant tumors, c-erb-B2, p-4EBP1, p-p70S6K, and p-S6 were expressed significantly more often in malignant tumors. Only p-4EBP1 expression demonstrated prognostic significance (P = .005), and only surgical stage and p-4EBP1 expression had statistical significance in the multivariate analysis.

CONCLUSIONS

In patients with ovarian carcinoma, significant expression of p-4EBP1 was associated with high-grade tumors and a poor prognosis, regardless other oncogenic alterations upstream. This finding supports the study of this factor as a hallmark or pivotal factor in cell signaling in ovarian carcinoma that may crucial in the transmission of the proliferation cell signal and may reflect the real oncogenic role of this pathway in ovarian tumors.