Le cancer du poumon est un problème majeur de santé publique et dont le coût humain et social est sans cesse en augmentation au cours des dernières années. Parmi les nombreux médiateurs susceptibles de jouer un rôle dans la croissance tumorale, nous avons étudié en détails le système des ADAM et ADAMTS protéases. Les ADAMs sont des enzymes aux fonctionnalités multiples qui interviennent dans de nombreux processus physiologiques et pathologiques. Parmi ces différents processus, certains concernent des modulations de la structure ou de létat de la matrice extracellulaire et dautres des boucles dinteractions entre différents types cellulaires reliés par des médiateurs protéiques. Les modulations apportées à ce système par les ADAM protéases résident donc dans lactivation ou linhibition de certains processus biologiques par clivage de molécules ou activation des récepteurs. Au cours de la première partie de notre travail, nous avons étudié lexpression de différentes ADAM(TS) protéases sélectionnées sur base de la littérature comme potentiellement impliquées dans la régulation de la croissance tumorale. L'analyse d'échantillons de cancers pulmonaires humains a été réalisée en collaboration avec le Professeur P BIREMBAUT (Unité INSERM U 514, Reims). Nous avons mis en évidence que lADAM-12 (forme complète membranaire) est surexprimée et que lADAMTS-1 est moins exprimée dans les tissus tumoraux pulmonaires obtenus par résection chirurgicale par rapport à des échantillons correspondants prélevés en zone saine. Ces variations ont été vérifiées par Real-Time PCR et par western blots. Les niveaux dexpression de lADAM-12 sont corrélés à lexpression des mRNAs codant pour les isoformes 121 et 165 (qui sont pro-angiogènes) du VEGF-A. Une immunohistochimie marquant l'ADAM-12 a montré une expression de cette protéase principalement dans les cellules tumorales ; l'ADAMTS-1 par contre, est surtout exprimée dans le tissu bronchique sain. Les lignées de cellules pulmonaires issues de cellules épithéliales bronchiques et alvéolaires ont été caractérisées pour leur expression en ADAM-12 et ADAMTS-1. LADAM-12 et lADAMTS-1 sont surexprimées par les cellules de type BZR et BZR T33 qui forment des tumeurs chez les souris et qui ont un caractère agressif. Au cours de ces travaux, nous avons donc clairement pu identifier deux protéases dont l'expression est modulée dans nos échantillons de tissu pulmonaire sain ou tumoral. L'ADAM-12, surexprimée dans les tumeurs, serait un modulateur "positif" de la progression tumorale et l'ADAMTS-1, dont lexpression est moindre dans les tumeurs semble être un modulateur négatif du développement tumoral (Rocks et al, Br J Cancer, 2006). Nous avons focalisé la suite de nos travaux sur létude des effets de lADAM-12 et de lADAMTS-1 sur différents phénomènes biologiques impliqués dans la progression tumorale. Sur base de l'analyse des échantillons de cancers pulmonaires, l'ADAM-12 est donc apparue comme un candidat potentiel impliqué dans la progression tumorale. Nous avons ainsi généré des clones surexprimant lADAM-12 à partir de cellules épithéliales bronchiques immortalisées (BEAS-2B). Ces clones ont été caractérisés et leur production dADAM-12 a été démontrée par RT-PCR et cytométrie de flux. Le comportement des cellules surexprimant lADAM-12 a ainsi pu être comparé à celui des cellules parentales transfectées avec le vecteur vide (contenant uniquement le gène de la résistance à la néomycine). Différentes expériences in vitro ont été réalisées sur ces cellules. Il ressort de lensemble de cette caractérisation que les cellules surexprimant lADAM-12 présentent une prolifération et une capacité à former des colonies en agar mou accrues par rapport aux cellules parentales. De plus, les cellules surexprimant lADAM-12 ont une sensibilité vis-à-vis de lapoptose diminuée par rapport aux clones contrôles. Ces processus sont dépendants dune augmentation de la production dHB-EGF mature par les clones surexprimant lADAM-12. Les clones surexprimant lADAM-12 ainsi que les clones contrôle ont été implantés au sein du tissu pulmonaire de souris et injectés dans le tissu sous-cutané. Il ressort de ces expériences que les cellules de type BEAS-2B transfectées ou non par lADAM-12 sont peu tumorigènes qu'elles soient implantées dans un site orthotopique (intra-pulmonaire) ou hétérotopique (sous-cutané) dans les souris SCID. En dépit du fait que l'ADAM-12 stimule la prolifération cellulaire et protège les cellules de lapoptose in vitro, sa surexpression nest pas suffisante en soi pour développer un phénotype tumorigène in vivo (Rocks et al, Cell Prolif, in press). Dans la troisième partie de notre travail, nous avons généré à partir de la lignée dérivée de cellules épithéliales bronchiques tumorales BZR des clones transfectés de façon stable qui surexpriment lADAMTS-1 humaine complète. Ceci est confirmé par la présence de bandes de 87 kDa en Western Blot, représentant la forme complète et active de cette protéase. In vitro, nous navons pas pu mettre en évidence de différence de prolifération, de migration, dinvasion et dapoptose entre les différents clones étudiés. Nous avons ensuite procédé à limplantation au niveau sous cutané dans des souris immunodéficientes de populations cellulaires transfectées de façon stable avec le gène de lADAMTS-1. Nous avons ainsi évalué si la surexpression de cette protéase modifiait le comportement de ces cellules en termes de prolifération in vivo. Les tumeurs formées à partir de cellules transfectées avec la forme complète de lADAMTS-1 présentent une taille plus importante que les tumeurs formées à partir de cellules BZR contrôle. Un immunomarquage pour le Proliferating Cell Nuclear Antigen (PCNA) a révélé des scores de prolifération cellulaire plus élevé dans les tumeurs dérivées de populations cellulaires surexprimant lADAMTS-1. De plus, lanalyse histochimique des tumeurs a montré, dans les tumeurs surexprimant lADAMTS-1, la présence de structures stromales composées de fibronectine (WB), collagène (marquées positivement par coloration au safran, WB) et de myofibroblastes (positifs pour lα-actine des muscles lisses). Afin détudier le potentiel chimiotactique de lADAMTS-1 sur les fibroblastes, nous avons utilisé le modèle des chambres de Boyden. Les chambres du dessous ont été remplies avec des milieux conditionnés dérivés de populations de cellules transfectées ou non avec la forme complète de lADAMTS-1. Les milieux conditionnés de cellules surexprimant lADAMTS-1 ont des capacités dattraction plus importantes sur les fibroblastes que les milieux conditionnés dérivés de cellules contrôles. Cependant, lajout dADAMTS-1 recombinante au milieu conditionné par des cellules contrôles nest pas suffisant pour augmenter la migration des fibroblastes. Nous avons donc mesuré lexpression de facteurs potentiellement impliqués dans le remodelage de la matrice extracellulaire et dans la migration de fibroblastes. Les tumeurs surexprimant lADAMTS-1 ont des taux plus élevés de MMP-13, TGF-β1 et dIL-1β. De plus, un anticorps bloquant les effets du TGF-β1 et/ou de lIL-1β diminue la migration des fibroblastes en chambre de Boyden. En résumé, nous montrons par ce travail, que les cellules BZR transfectées au moyen de la forme complète de lADAMTS-1, forment des tumeurs plus larges, infiltrées par des myofibroblastes, suggérant que les interactions tumeur-stroma influencent la prolifération de cellules tumorales En conclusion, nos travaux ont identifié que lexpression de lADAM-12 et lADAMTS-1 est modulée dans des tumeurs bronchiques humaines. LADAM-12 joue un rôle dans la prolifération cellulaire en activant le clivage de facteurs de croissance membranaires qui sont des ligands de lEGFR. Le rôle de lADAMTS-1 apparaît comme beaucoup plus complexe et nos travaux montrent que lADAMTS-1 peut influencer la croissance tumorale in vivo en modulant la composition cellulaire et matricielle du stroma. Collectivement, ces travaux confirment le rôle clé joué par les protéases de la famille des ADAMs et ADAMTS dans le développement du cancer et identifient ces enzymes comme des cibles thérapeutiques potentielles.

Au travers d’études cliniques et biologiques, de méta-analyses et de revues systématiques de la littérature, nous avons étudié les CBNPC de stade III sur le plan thérapeutique et cherché des facteurs pronostiques pour la survie dans le but d’améliorer la classification internationale et, à terme, de permettre une meilleure prise en charge des patients inclus dans ce groupe hétérogène de tumeurs. Dans le cadre d’essais randomisés, nous avons montré qu’un abord multimodal et multidisciplinaire permettait d’améliorer le pronostic des patients atteints d’un CBNPC de stade III. Le traitement des tumeurs non résécables implique une combinaison de chimiothérapie et de radiothérapie, dont l’administration concomitante doit être proposée aux patients aptes à la tolérer. La chimiothérapie doit être incluse dans le schéma thérapeutique des tumeurs potentiellement résécables. Elle permet une résection chirurgicale complète chez des patients sélectionnés dont la tumeur était initialement non résécable. Nous avons déterminé que des caractéristiques cliniques (l’indice de performance et l’âge), biologiques (les taux sanguins de polynucléaires neutrophiles, d’hémoglobine et de plaquettes, la bilirubinémie) et propres à la tumeur (l’extension locale [T3-4] et ganglionnaire [N3]) avaient une valeur pronostique indépendante pour la survie. Ceci nous a permis d’aboutir à une proposition de modification de la classification internationale concernant les CBNPC de stade III. Bien que pris individuellement, les facteurs biologiques que nous avons étudiés (p53, EGF-R, TTF-1, Mdm2) n’aient pas de valeur pronostique pour la survie, nous avons montré que la combinaison EGF-R+/TTF1- était un facteur pronostique indépendant en analyse multivariée pour la survie spécifique au cancer bronchique. Nous avons finalement évalué le rôle pronostique de la tomodensitométrie par émission de positrons et de la mesure semi-quantitative de captation du 18F-FDG (SUV) sur la survie des patients atteints de CBNPC et montré qu’un SUV élevé était un facteur de mauvais pronostic pour la survie.

The RAF-MEK-ERK is an important signaling pathway that controls cellular proliferation, differentiation and survival. Recent reports indicate that R-RAF is mutated at a high frequency in human cancer. The mutations are clustered in the glycine-rich loop and activation segment which are encoded by exon 11 and exon 15, respectively. Among these mutations, V600E is the most prevalent found in varieties of human cancers, include melanoma and thyroid carcinomas. In this thesis, we analyzed 86 human cancer specimens, including 62 lung cancers and 24 esophageal cancers, for the mutation of exons 11 and 15 by PCR and direct DNA sequencing. However, we can not detect any mutation in these two exons in these clinical samples, these results suggest indicating that BRAF mutation might be rare and analysis of larger sample size is needed to confirmed this conclusion.

Small Cell Lung Cancer (SCLC) is a very aggressive neuroendocrine tumour of the lung, which demonstrates a 5 year survival of only 10% for extensive stage disease (20-30% for limited stage), with only modest improvement over the last few decades. Identification of new molecular diagnostic and therapeutic targets is thus imperative. Previous efforts in identifying molecular changes in SCLC by gene expression profiling using microarrays have facilitated disease classification but yielded very limited information on SCLC biology. Previous DNA studies have been successful in identifying several loci important to SCLC. However the low resolution of conventional chromosomal Comparative Genomic Hybridization (CGH) has limited the findings to large chromosomal regions with only a few specific candidate genes discovered to date. Thus, to further understand the biological behaviour of SCLC, better methods for studying the genomic alterations in SCLC are necessary. This thesis highlights the development of array CGH technology for the high resolution dissection of aneuploidy in cancer genomes and the application of this new technology to the study of SCLC. I present the development of the first whole genome CGH array which offered unprecedented resolution in the profiling of cancer genomes allowing fine mapping of genes in a single experiment. Through application of DNA based analysis in conjunction with integrated expression analysis and comparison of SCLC to less aggressive non-small cell lung tumours I have identified novel patterns of pathway disruption specific to SCLC. This included alteration to Wnt pathway members and striking patterns of cell cycle activation through predominantly downstream disruption of signalling pathways including direct activation of the E2F transcription factors, which are normally repressed by the Rb gene. Analysis of targets of the E2F/Rb pathway identified EZH2 as being specifically hyper-activated in SCLC, compared to NSCLC. EZH2 is a polycomb group gene involved in the control of many cellular functions including targeted DNA methylation and escape from senescence in hematopoietic stem cells. Taken together these results suggest that in SCLC, downstream disruption may replace multiple upstream alterations leading to activation independent of a specific mitogenic pathway, and that EZH2 represents a potentially important therapeutic target.

Calreticulin (CRT) is a multifunctional Ca2+ dependent chaperone protein, which is localized to the endoplasmic reticulum and plays many important biological roles. In addition to its critical role in cardiovascular development, CRT has been reported to be important for cell migration, adhesion and apoptosis. A few studies have also suggested different roles for exogenous CRT in angiogenesis and tumor growth however no direct evidence for the role of endogenous CRT in these processes is available. To study the in vivo role of CRT in angiogenesis and vascular development, we generated a transgenic mouse overexpressing CRT under the control of the Tie2 promoter (referred to as Tie2-CRT) which is active in both endothelial cells and hematopoietic stem cells (HSCs). The main phenotype of these mice is an increased incidence of lung tumors. These tumors have been characterized according to their histochemical properties as being adenocarcinoma with a Surfactant Protein-C positive (SP-CPos) and Clara Cell Protein negative (CC10Neg) phenotype suggesting an alveolar origin for these tumors. We observed that during the early stages of tumor formation, the lungs show signs of increased inflammation as evidenced by congestion, reddish discoloration and the accumulation of inflammatory cells. We have also identified that the early stage tumors contain cells that express exogenous CRT and HSC markers including CD133, Sca-1, and c-Kit. As the tumor progresses to a fully developed adenocarcinoma, these cells lose the expression of exogenous CRT and HSCs markers and gain an alveolar type II phenotype (SP-CPos). In vitro evaluation of tumor progression using lung tumor cells from Tie2-CRT mice demonstrated a differentiation dependent expression of HSC markers by tumor cells supporting the hypothesis that HSCs might be the cells of origin for the lung tumors observed in Tie2-CRT mice. In summary, the results from this study provide evidence that lung tumors from the Tie2-CRT mice are non-epithelial in origin and that the undifferentiated population of tumor cells have HSC characteristics. After differentiation, these cells lose their stem cell phenotype and acquire an epithelial phenotype. This study is the first to examine the potential link between CRT and lung cancer development.

Calreticulin (CRT) is a multifunctional Ca2+ dependent chaperone protein, which is localized to the endoplasmic reticulum and plays many important biological roles. In addition to its critical role in cardiovascular development, CRT has been reported to be important for cell migration, adhesion and apoptosis. A few studies have also suggested different roles for exogenous CRT in angiogenesis and tumor growth however no direct evidence for the role of endogenous CRT in these processes is available. To study the in vivo role of CRT in angiogenesis and vascular development, we generated a transgenic mouse overexpressing CRT under the control of the Tie2 promoter (referred to as Tie2-CRT) which is active in both endothelial cells and hematopoietic stem cells (HSCs). The main phenotype of these mice is an increased incidence of lung tumors. These tumors have been characterized according to their histochemical properties as being adenocarcinoma with a Surfactant Protein-C positive (SP-CPos) and Clara Cell Protein negative (CC10Neg) phenotype suggesting an alveolar origin for these tumors. We observed that during the early stages of tumor formation, the lungs show signs of increased inflammation as evidenced by congestion, reddish discoloration and the accumulation of inflammatory cells. We have also identified that the early stage tumors contain cells that express exogenous CRT and HSC markers including CD133, Sca-1, and c-Kit. As the tumor progresses to a fully developed adenocarcinoma, these cells lose the expression of exogenous CRT and HSCs markers and gain an alveolar type II phenotype (SP-CPos). In vitro evaluation of tumor progression using lung tumor cells from Tie2-CRT mice demonstrated a differentiation dependent expression of HSC markers by tumor cells supporting the hypothesis that HSCs might be the cells of origin for the lung tumors observed in Tie2-CRT mice. In summary, the results from this study provide evidence that lung tumors from the Tie2-CRT mice are non-epithelial in origin and that the undifferentiated population of tumor cells have HSC characteristics. After differentiation, these cells lose their stem cell phenotype and acquire an epithelial phenotype. This study is the first to examine the potential link between CRT and lung cancer development.

Small Cell Lung Cancer (SCLC) is a very aggressive neuroendocrine tumour of the lung, which demonstrates a 5 year survival of only 10% for extensive stage disease (20-30% for limited stage), with only modest improvement over the last few decades. Identification of new molecular diagnostic and therapeutic targets is thus imperative. Previous efforts in identifying molecular changes in SCLC by gene expression profiling using microarrays have facilitated disease classification but yielded very limited information on SCLC biology. Previous DNA studies have been successful in identifying several loci important to SCLC. However the low resolution of conventional chromosomal Comparative Genomic Hybridization (CGH) has limited the findings to large chromosomal regions with only a few specific candidate genes discovered to date. Thus, to further understand the biological behaviour of SCLC, better methods for studying the genomic alterations in SCLC are necessary. This thesis highlights the development of array CGH technology for the high resolution dissection of aneuploidy in cancer genomes and the application of this new technology to the study of SCLC. I present the development of the first whole genome CGH array which offered unprecedented resolution in the profiling of cancer genomes allowing fine mapping of genes in a single experiment. Through application of DNA based analysis in conjunction with integrated expression analysis and comparison of SCLC to less aggressive non-small cell lung tumours I have identified novel patterns of pathway disruption specific to SCLC. This included alteration to Wnt pathway members and striking patterns of cell cycle activation through predominantly downstream disruption of signalling pathways including direct activation of the E2F transcription factors, which are normally repressed by the Rb gene. Analysis of targets of the E2F/Rb pathway identified EZH2 as being specifically hyper-activated in SCLC, compared to NSCLC. EZH2 is a polycomb group gene involved in the control of many cellular functions including targeted DNA methylation and escape from senescence in hematopoietic stem cells. Taken together these results suggest that in SCLC, downstream disruption may replace multiple upstream alterations leading to activation independent of a specific mitogenic pathway, and that EZH2 represents a potentially important therapeutic target.

Lung cancer is the leading cause of cancer related death worldwide; despite recent treatment developments survival rates remain poor and are closely related to the patient’s clinical stage. Even among patients with early-stage lung cancer, which is amenable to surgical resection, prognosis is highly variable; some go on to live disease-free for many years whereas others quickly recur. Although post-operative chemotherapy is available it has associated morbidities and it is unclear which patients would benefit; therefore, there is a need for more effective stratification of patients. The adenocarcinoma sub-type of lung cancer is known to be morphologically heterogeneous however the majority of observed growth patterns, assessed by light microscopy, can be characterised into one of five formations: lepidic, papillary, acinar, solid and micropapillary. The morphology of each tumour has been proposed as a marker of prognosis and several studies have published a link between the most prevalent growth pattern and prognosis; suggesting those with predominantly solid or micropapillary tumours to have the least favourable outcomes. Indeed, it is now recommended that the proportion of each growth pattern and the predominant growth pattern should be reported for all resected lung adenocarcinomas; although no differential treatments have been recommended based on this assessment. The aim of this study was to determine whether combining the analysis of clinicopathological; morphological; and candidate protein, molecular genetic and transcriptomic characteristics in a single cohort of 208 early-stage, resected, adenocarcinomas with clinical follow-up could be used to identify a subset of patients at high risk of recurrence. Comprehensive morphological analysis was carried out including the presence, proportion and number of individual growth patterns; the predominant growth pattern as well as features previously associated with tumour grade (the presence of large numbers of mitotic figures, apoptotic bodies, inflammatory cells, prominent nucleoli, pleomorphic tumour cells, dyscohesive tumour cells and large amounts of necrosis and scar tissue within the tumour). In addition, gene expression was assessed using a panel of 31 cell-cycle related genes, EGFR and KRAS mutation status was determined, and EGFR and TTF1 protein expression investigated. In this study the predominant growth pattern defined by histopathology showed no ability to identify a group of patients with a poorer prognosis either in univariable or multivariable analysis. Univariable analysis identified nodal status [hazard ratio of N1 compared to N0 was 2.16 (95% CI 1.48 to 3.16, p< 0.0005)], clinical stage [hazard ratios of stage IIa and IIb compared to stage Ia were 3.15 (95% CI 1.73 to 5.73, p< 0.0005) and 2.22 (95% CI 1.10 to 4.48, p= 0.025) respectively], the presence of a significant amount of the papillary growth pattern [the hazard ratio of those with less than 8.5% papillary pattern was 0.657 (95% CI 0.44 to 0.98, p= 0.035)], and overall tumour grade score (including an assessment of necrosis, mitosis, apoptosis, nucleoli, scar tissue and inflammatory cells) [hazard ratio 1.71 (95% CI 1.14 to 2.56, p= 0.008)] as significantly associated with prognosis. Multivariable analysis using Cox’s proportional hazards model identified clinical stage (p< 0.0005), the presence of a significant amount of the papillary growth pattern (p= 0.048) and the presence of large numbers of mitotic figures (p=0.029) and apoptotic bodies (p= 0.015) as independently associated with disease specific survival; although after correction for type I errors only clinical stage remained significantly associated with prognosis with patients with stage Ia disease having a significantly better outcomes [hazard ratio 0.418 (95% CI 0.20 to 0.86)]. Classification and regression tree analysis (CART) was used to further explore the data and to develop decision trees for the prognostication of early-stage lung adenocarcinoma patients. Receiver operating characteristic analysis based on 5- year survival showed a minimal improvement in the area under the curve between a model utilizing currently available clinicopathologic characteristics only [nodal status and lesion size, (area under the curve 0.704, 95% CI 0.631 to 0.777)] and one including growth pattern characteristics [area under the curve 0.725, 95% CI 0.654 to 0.796]. The greatest improvement in prognostic accuracy was observed when gene expression analysis was included in the analysis [area under the curve 0.749, 95% CI 0.673 to 0.825]; however even this showed very little impact compared to routinely used clinicopathologic variables. This analysis suggests that the recommended characterisation of lung adenocarcinoma histology is not a robust predictor of patient outcomes; even a broader model which also included indicators of tumour grade and molecular characteristics was unable to identify a model sufficiently robust to implement into clinical practice and thereby potentially alter patient treatment. Currently routinely collected clinical characteristics; including nodal status, size and clinical stage; continue to provide the most robust method of prognostication and detailed and time-consuming morphological analysis offers no significant benefit to the patient.

Mammalian homolog Tribbles (Trbs) is a newly characterized protein family that includes three different isoforms: Trb1, Trb2, and Trb3. Tribbles are serine/threonine kinases lacking catalytic activity, thus their classification as pseudokinases. Despite their catalytic inactivity, Tribbles can interact with different proteins and regulate different biological functions. The most studied tribble family member, Trb3, was reported to play a major role in Drosophila's ventral furrow formation. Further studies revealed that Trb3 is also involved in diabetes, stress-response, and development. Previously, Trb3 upregulation was detected in certain types of cancer but its function remains unknown. The goal of our study is to gain a better understanding of the biological function of Trb3 in cancer, including the molecular mechanism of action. Using the cohort analysis, we identified higher levels of Trb3 in the lung tumor compared to the normal tissue. Furthermore, higher Trb3 expression in the lung tissue was associated with a poor survival in cancer patients. Silencing of Trb3 in A549 promoted cell growth. On the other hand, overexpression of Trb3 in NCI-H358 inhibited cell growth. The analysis of cell cycle gene profiling revealed a decrease in several genes that are essential for cell cycle progression in S phase in Trb3 overexpressed NCI-H358. The cell proliferation protein, Ki67, was also decreased in Trb3 overexpressed NCI-H358 cells. Moreover, Tb3 overexpressed cells formed higher colony number in soft agar assay and depicted higher migration ability in the Boyden chamber assay. Mesenchymal markers SNAIL, TWIST and N-cadherin were upregulated while epithelial E-cadherin was significantly reduced. Interestingly, prosurvival protein Akt was also reduced post Trb3 overexpression. Trb3 expression was associated with a poor survival. However, we discovered that Trb3 overexpression inhibited cell growth. Thus, we hypothesized that Trb3 expression might contribute to tumorigenesis during cellular metabolic stress. In order to understand the potential role of Trb3 in metabolic stress, NCI-H358 cells were treated with five different cellular stressors to mimic the tumor microenvironment. All stressors used were shown to induce endogenous Trb3 expression. Moreover, stress proteins ATF4, CHOP and ASNS were induced by all stressors. One of the stressors used was rotenone, an inhibitor of the complex I of the electron transport chain. Rotenone treatment induced Trb3 expression. This expression inversely correlated with cytochrome C expression. Furthermore, Trb3 expression positively correlated with the expression of mitophagic genes PINK1, Parkin and p62, which suggest that Trb3 is induced during ROS-mediated oxidative stress to participate in the clearing of damaged mitochondria. This targeted clearing of the mitochondria, a process known as mitophagy is essential for the cell survival of the lung cancer cells. Last, Trb3 overexpression rendered cancer cells resistant to docetaxel and cisplatin, two chemotherapeutic drugs used in lung cancer treatment. On the other hand, Trb3 depleted cells were more sensitive to the drugs. Our results suggest that Trb3 is activated in the primary tumor to promote metabolic adaptation through cell cycle arrest and the inhibition of aerobic glucose metabolism through Akt inhibition. Furthermore, Trb3 is essential during cell survival post ROS-mediated stress and participates in the clearing of damaged mitochondria during mitophagy. Last, stress-mediated activation of Trb3 confers lung cancer cells with chemoresistance and suggest that Trb3 could be a potential target in lung cancer therapy.

Doctor of Philosophy / Department of Agronomy / Masaaki Tamura / Over the years proteins/peptides have evolved as promising therapeutic agents in the treatment of cancer. Considering the advantages of peptides such as their small size, ease of synthesis, tumor-penetrating ability and bio-compatibility, present report discusses proof of concept for 1. C1B5 peptide of protein kinase Cγ and a low dose of gemcitabine combination treatment for peritoneally disseminated pancreatic cancer and 2. dTAT peptide nanoparticles mediated gene (angiotensin II type 2 receptor gene) therapy for lung cancer. 1. A significant reduction in intraperitoneally (IP) transplanted pancreatic carcinoma growth was demonstrated with C1B5 peptide and gemcitabine co-treatment in an immunocompetent mouse model. Increased number of Granzyme B positive cells was observed in treated mice ascites, suggesting the involvement of immune response in tumor attenuation. The strong effect observed in combination treatment might be because of increase in lymphocyte recruitment by gemcitabine followed by C1B5 peptide mediated CD8+ T-cells or NK cells activation apart from direct cancer cell apoptosis. 2. To test dTAT peptide nanoparticles (dTAT NPs) mediated therapeutic gene delivery, luciferase reporter gene containing dTAT nanoparticles were synthesized (dTAT/pLUC/Ca2+). Synthesis conditions for nanoparticles were optimized based on dTAT/pLUC/Ca2+ nanoparticles transfection efficiency. With the optimized conditions, dTAT NPs containing AT2R, TRAIL or miR-34a pDNA (dTAT/pAT2R, dTAT/TRAIL or dTAT/miR- 34a) were synthesized. Therapeutic potential of these NPs was analyzed in lung adenocarcinoma containing mice by administering them intravenously (IV) or/and intratracheally (IV). Combination treatment with the IV injection of the new dTAT/pAT2R/Ca2+ formulation and the IT injection of the original dTAT/pAT2R/Ca2+ formulation is effective in attenuation of developed human bronchioloalveolar carcinoma in the SCID mouse lungs. Findings from the above mentioned studies have vital clinical relevance as it implies that peptides alone or when used as gene delivery systems may prove to be beneficial in the treatment of various stages of cancer.