Despite improvements in the clinical management of soft tissue sarcomas (STS), 50% of patients will die of metastatic disease that is largely unresponsive to conventional chemotherapeutic agents. The aims of this study were to identify genes and pathways that are dysregulated in progressive and metastatic STS. In addition to this, cell lines from fresh tumours were initiated and established, thus increasing the repository of cell lines available for functional studies. Recent advances in the understanding of the molecular biology of STS have thus far not resulted in the use of molecular markers for clinical prognostication. Identifying novel genes and pathways will lead to molecular diagnostic methods to better stratify prognostic groups and could identify cellular targets for more efficacious treatments. Gene expression profiling of sarcoma cell lines of increasing metastatic potential revealed over-expression of genes involved in the epidermal growth factor (EGF) and transforming growth factor beta (TGFb) pathways. Factors involved in invasion and metastasis such as integrins and MMPs were over-expressed in the cell lines with higher metastatic potential. The developmental Notch pathway and cell cycle regulators were also dysregulated. NDRG1 was significantly over-expressed in the high grade sarcoma cell line, a novel finding in sarcomas. The expression of EGFR, NDRG1 and other genes from the above pathways was validated using quantitative RT-PCR in real time (qRT-PCR). A tissue microarray (TMA) comprising STS of varying tumour grades was constructed for high throughput assessment of target proteins. EGFR, its activated form and its signal transducers were investigated using immunohistochemistry (IHC). Activated EGFR (HR 2.228, p < 0.001) and phosphorylated Akt (HR 2.032, p = 0.003) were found to be independent predictors of overall survival and both correlated with tumour grade. Of the several STS cultures initiated and maintained, two of these cell lines were fully characterised in terms of cytogenetics, telomerase and alternate lengthening of 5 telomeres (ALT) status, KIT and TP53 mutation and the expression of certain biomarkers using both qRT-PCR and IHC. In summary, transcript profiling identified several potential biomarkers of tumour progression and metastasis in STS. Crucially, activated EGFR and pAkt were found in a cohort of STS samples to correlate with clinical outcome, identifying them as potential diagnostic and therapeutic targets in the treatment of STS. Activated EGFR can be used as a diagnostic marker for patient selection, as well as for target effect monitoring. Furthermore, the cell lines established in this project will serve as valuable tools in future preclinical studies.

Responsable d'environ 30000 décès/an en France, le cancer du poumon est un problème de santé publique majeur. Un des enjeux actuels est d'adapter le traitement du cancer du poumon pour proposer des thérapeutiques ciblées plus efficaces et moins agressives. Les inhibiteurs de l'activité tyrosine kinase du récepteur de l'EGF (EGFR-TKI, gefitinib et erlotinib) constituent un réel progrès pour le traitement des cancers du poumon. Cependant, des mécanismes de résistance ont été décrits et des traitements combinés de thérapies ciblées avec des EGFR-TKI pourraient permettre de surmonter les résistances dans les cancers du poumon.Dans ce contexte, nous avons étudié les mécanismes impliqués dans la résistance à ces traitements. Nous montrons que l'activation de la voie de signalisation PI3K/AKT joue un rôle majeur dans la résistance aux EGFR-TKI, en inhibant l'apoptose par des mécanismes dépendant de l'acétylation. Les histones déacétylases (HDACs) et les sirtuines interviennent dans ces mécanismes de résistance, en modulant l'activation de la voie PI3K/AKT et l'apoptose. Ainsi l'utilisation d'inhibiteurs des HDACs (HDACi) et des sirtuines permettent de restaurer la sensibilité aux EGFR-TKI. Ces résultats confirment l'intérêt thérapeutique de l'association EGFR-TKI/HDACi et montrent le potentiel thérapeutique d'associer des inhibiteurs de l'EGFR et de la voie PI3K/AKT pour contourner la résistance aux EGFR-TKI.Les molécules thérapeutiques doivent atteindre spécifiquement le site tumoral, nécessitant parfois de les protéger contre leur dégradation, de réduire leurs effets indésirables, et de contrôler leur libération dans le temps et l'espace, à l'aide de transporteurs. Ainsi dans la deuxième partie de cette thèse, nous avons évalué les capacités de ciblage des tumeurs pulmonaires de nanoparticules à base de copolymère amphiphile, contenant une partie polysaccharidique hydrophile (le hyaluronane) et une partie polypeptidique hydrophobe (le poly(γ‐benzyl L‐glutamate, PBLG). Nos travaux mettent en évidence la capacité de ciblage tumoral de ces nanoparticules injectées par voie intraveineuse, ouvrant ainsi de nouvelles perspectives thérapeutiques. Notre objectif est de charger les combinaisons de traitements EGFR-TKI/HDACi que nous avons identifiées dans ces vecteurs, afin de traiter les tumeurs pulmonaires résistantes aux EGFR-TKI. / Responsible of 30000 deaths each year in France, lung cancer is a major public health problem. One of the current challenges is to adapt the treatment of lung cancer to offer more effective and less aggressive targeted therapies. EGFR tyrosine kinase inhibitors (EGFR-TKI, gefitinib and erlotinib) represent a real progress in lung cancer therapy. However resistance mechanisms have been described and combination of targeted therapy with EGFR-TKI could overcome resistance in lung cancer.In this context, we studied mechanisms involved in resistance to EGFR-TKI. We show that PI3K/AKT activation is a major pathway leading to EGFR-TKI resistance leading to apoptosis inhibition through acetylation-dependent mechanisms. Histone deacetylase (HADCs) and sirtuin are involved in these mechanisms and modulate PI3K/AKT activation and apoptosis. The use of HDACs inhibitors (HDACi) and sirtuins inhibitors thus restores the sensitivity to EGFR-TKI. Altogether these results confirm the therapeutic effect of the EGFR-TKI/HDACi combination and show the therapeutic potential of the association of EGFR and PI3K/AKT inhibitors to overcome EGFR-TKI resistance.Therapeutic molecules must specifically reach the tumor site, sometimes requiring to protect them against degradation, to reduce their side effects, and to control their release in time and space, using transporters. In the second part of this thesis, we have thus evaluated the lung tumors targeting capabilities of amphiphilic copolymer-based nanoparticles, containing an hydrophilic polysaccharidic block (hyaluronan) and an hydrophobic polypeptidic block (the poly(γ‐benzyl L‐glutamate PBLG). Our work highlights the tumor targeting capability of these nanoparticles injected intravenously, offering new lung cancer therapy perspectives. Our aim is to load the drugs combination (EGFR-TKI/HDACi) in these vectors, to treat the lung tumors resistant to EGFR-TKI.

L'EGFR est un récepteur transmembranaire à activité tyrosine kinase (TK) qui transduit des signaux de prolifération et de survie cellulaire. Dans les cancers du poumon, son activité est fréquemment dérégulée par surexpression et/ou par mutation au niveau de son domaine TK. Ces mutations sont principalement de deux types (EGFR-L858R et EGFR-Del19) et sont dites activatrices car elles induisent une activation constitutive des signalisations oncogéniques de l'EGFR. Elles sont aussi un facteur prédictif de réponse aux EGFR-TKIs qui inhibent spécifiquement ce récepteur. P14ARF est un suppresseur de tumeur qui restreint la prolifération cellulaire et maintient la stabilité génomique. Nous avons décrit son inactivation dans les cancers du poumon et démontré que son expression freine leur développement. Nos résultats récents montrent que l'expression de p14ARF est inhibée dans une très grande majorité d'adénocarcinomes pulmonaires présentant une mutation activatrice de l'EGFR. Sur la base de ces résultats nous avons émis l'hypothèse que l'inhibition de l'expression de p14ARF contribuerait à l'expansion clonale des tumeurs porteuses d'un EGFR muté. P14ARF pourrait ainsi être un frein à l'activité oncogénique de l'EGFR.Dans différents modèles d'adénocarcinomes pulmonaires exprimant un mutant EGFR-L858R nous montrons que l'expression transitoire de p14ARF active une signalisation pro-apoptotique dépendante de STAT3 et de Bcl2. En retour, l'EGFR inhibe l'expression de p14ARF et bloque ses fonctions pro-apoptotiques. Nous montrons aussi que l'activation de l'EGFR (sauvage ou muté) inhibe l'expression de p14ARF à un niveau transcriptionnel. Ceci implique une translocation nucléaire de l'EGFR contrôlée par les PI3Ks de classe III (Vps34) et la fixation de l'EGFR sur le promoteur de ARF. L'ensemble de ces travaux identifie pour la première fois un lien fonctionnel entre les voies de signalisation de l'EGFR et de p14ARF. Ils mettent en évidence un nouveau mécanisme de progression tumorale par lequel une signalisation nucléaire de l'EGFR inactive le suppresseur de tumeur p14ARF afin de permettre la croissance tumorale. / EGFR is a transmembrane tyrosine kinase (TK) receptor which activates proliferative and survival signals. In lung cancer, its activity is frequently deregulated by overexpression and/or mutation in its TK domain. These mutations are mainly of two types (L858R and Del19) and are called « driver mutations » because they induce constitutive activation of EGFR oncogenic signaling. They also represent a predictive responsive factor to EGFR TKIs that specifically inhibit this receptor. P14ARF is a tumor suppressor that restricts cellular proliferation and maintains genomic stability. We described its inactivation in lung cancer and demonstrated that its expression inhibits their development. Our recent results show that the expression of p14ARF is inhibited in a majority of lung adenocarcinomas expressing an activating EGFR mutation. Based on these results we hypothesized that inhibition of p14ARF expression contributes to clonal expansion of mutated EGFR-bearing tumor. P14ARF could be a break to EGFR oncogenic activity.In different models of lung adenocarcinoma expressing a L858R EGFR mutant we show that transient expression of p14ARF activates a pro-apoptotic STAT3/Bcl-2-dependent signaling pathway. In turn, EGFR inhibits the expression of p14ARF and blocks its pro-apoptotic function. We also show that EGFR (wild type or mutated) activation inhibits the expression of p14ARF at the transcriptional level. This implies a nuclear translocation of EGFR controlled by Class III PI3K (Vps34) and its fixation to the ARF promoter. This work identifies for the first time a functional link between EGFR and p14ARF signaling pathways. They highlight a new mechanism of tumor progression by which a nuclear EGFR signaling inactivates the tumor suppressor p14ARF to allow tumor growth.

Submitted by Luciana Ferreira (lucgeral@gmail.com) on 2017-06-05T10:50:16Z No. of bitstreams: 2 Dissertação - Thiago David Alves Pinto - 2017.pdf: 3530254 bytes, checksum: c69d231fc95105583f213b9560d72667 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2017-06-05T10:50:51Z (GMT) No. of bitstreams: 2 Dissertação - Thiago David Alves Pinto - 2017.pdf: 3530254 bytes, checksum: c69d231fc95105583f213b9560d72667 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2017-06-05T10:50:51Z (GMT). No. of bitstreams: 2 Dissertação - Thiago David Alves Pinto - 2017.pdf: 3530254 bytes, checksum: c69d231fc95105583f213b9560d72667 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2017-05-19 / Epidermal growth factor receptor inhibitors represent a treatment option with proven efficacy for patients with metastatic colorectal carcinoma. However, patients with activating mutations in KRAS and NRAS have no response. Currently, wild KRAS and NRAS are prerequisite for this therapy. Furthermore, mutation tests are expensive and not easily accessible. EGFR expression by immunohistochemistry predicting the expanded RAS mutation (KRAS and NRAS), may allow the treatment to be instituted through a less costly and more accessible diagnostic method. The objective of this study is to test the correlation between EGFR cytoplasmic-membrane expression and the mutational status of the expanded RAS in colorectal carcinomas. An accuracy analysis was performed on 139 patients with colorectal carcinoma selected from the archives of the Instituto Goiano de Oncologia e Hematologia. The correlation between clinical-pathological data, the mutational state of the expanded RAS and the pattern of EGFR cytoplasmic-membrane expression were investigated. The expanded RAS mutation was detected in 78 (56.1%) cases. EGFR expression was stratified into 23 (16.5%) "Positives", 49 (35.2%) "Negatives" and 67 (48.2%) "Uncertain" cases. There was no significant association between age (p = 0.541 and 0.652), sex (p = 0.388 and 0.540), location (p = 0.393 and 0.098), histological type (p = 0.199 and 0.697), histological grade (p = 0.900 and 0.182) and stage (p = 0.533 and 0.053). The expression of EGFR stratified in "Positives", "Negatives" and "Uncertain" compared to the mutational status of the expanded RAS showed a strong association between the groups (p <0.001). Of the 23 "Positive" cases, 21 (91.3%) showed wild RAS gene. Of the 49 "Negative" cases, 41 (83.7%) presented mutation in the expanded RAS panel. Therefore, our study is pioneer in revealing that the EGFR cytoplasmic-membrane analysis, stratified in "Positives," "Negatives" and "Uncertain", predicts the mutational state of RAS in 51.7% of cases (p <0.001), with 86.1% accuracy. However further studies are needed to determine why nearly half of the cases are still doubtful. More complete analyzes contemplating the amplification of EGFR and mutations in other EGFR / MAPK cascade genes such as BRAF and PIK3CA, could enable a better stratification of the population. / Inibidores do receptor do fator de crescimento epidérmico representam uma opção terapêutica com eficácia comprovada para pacientes com carcinoma colorretal metastático. Porém, pacientes com mutações ativadoras em KRAS e NRAS não apresentam resposta. Atualmente, KRAS e NRAS selvagens são pré-requisito para esta terapêutica. Entretanto, a pesquisa de mutações é de alto custo e pouco acessível. A expressão do EGFR por imuno-histoquímica predizendo a mutação expandida do RAS (KRAS e NRAS) pode permitir que o tratamento seja instituído através de um método diagnóstico menos oneroso e mais acessível. O objetivo desse estudo é testar a correlação entre a expressão do EGFR e o estado mutacional do RAS expandido em carcinomas colorretais. Foi realizada uma análise de acurácia em 139 pacientes com carcinoma colorretal selecionados dos arquivos do Instituto Goiano de Oncologia e Hematologia. Foram pesquisados a correlação entre dados clínico-patológicos, estado mutacional do RAS expandido e padrão de expressão membrano-citoplasmática do EGFR. A mutação do RAS expandido foi detectada em 78 (56,1%) casos. A expressão do EGFR foi estratificada em 23 (16,5%) casos “Positivos”, 49 (35,2%) “Negativos” e 67 (48,2%) “Duvidosos”. Não foi identificada associação significativa em comparação a idade (p=0,541 e 0,652), sexo (p=0,348 e 0,540), localização (p=0,393 e 0,098), tipo histológico (p=0,199 e 0,697), grau histológico (p=0,900 e 0,182) e estadio (p=0,533 e 0,053). A expressão do EGFR estratificada em “Positivos”, “Negativos” e “Duvidosos” em comparação ao estado mutacional do RAS expandido mostrou forte associação entre os grupos (p<0,001). Dos 23 casos “Positivos”, 21 (91,3%) mostraram gene RAS selvagem. Dos 49 casos “Negativos”, 41 (83,7%) apresentaram mutação no painel RAS expandido. Portanto, nosso estudo é pioneiro em revelar que a análise membrano-citoplasmatica do EGFR estratificada em “Positivos”, “Negativos” e “Duvidosos” prediz o estado mutacional do RAS em 51,7% dos casos (p<0,001), com 86,1% de acurácia. Entretanto, novos estudos são necessários para determinar a razão de quase metade dos casos ser ainda duvidosa. Análises mais completas, contemplando a amplificação do EGFR e mutações em outros genes da cascata EGFR/MAPK como BRAF e PIK3CA podem possibilitar uma melhor estratificação desta população.

Le récepteur du facteur de croissance épidermique (EGFR) est une cible rationnelle pour les traitements anticancéreux des carcinomes épidermoïdes (CE). Cependant, seule une petite fraction de patients présente des avantages cliniques. Afin de comprendre l’échec de ces thérapies, j’ai étudié la voie de signalisation de l’EGFR en présence de fibroblastes associés aux carcinomes (FAC), principales cellules non malignes au sein des tumeurs. J'ai démontré que dans les CE, la voie de signalisation de l’EGFR coopère avec la rigidité de la matrice extracellulaire (MEC) induite par les FAC. Par la suite, j'ai cherché à résoudre les voies moléculaires qui sous-tendent cette coopération afin d'identifier de nouvelles cibles pharmaceutiques. Grâce à un criblage d'inhibiteurs pharmacologiques, j’ai identifié le vérapamil et le diltiazem, bloqueurs des canaux calcique CaV1, comme étant de puissants inhibiteurs de l'invasion des CE. Au niveau moléculaire, j'ai révélé que la rigidité de la MEC dérivée de la tumeur et la signalisation de l'EGFR déclenchent l'augmentation du calcium intracellulaire par le canal CaV1.1 dans les CE. Le blocage de l'activité de ces canaux inhibe l’invasion et la prolifération des cellules tumorale in vitro. Plus important encore, je démontre une forte réduction du développement des tumeurs dans deux modèles in vivo, à la fois dans un modèle de xénogreffe de cellules dérivées de patient atteint de carcinome de la tête et du cou, et dans un modèle CE cutané chez la souris. Par conséquent, je suggère une réaffectation du vérapamil et du diltiazem en tant qu’agents anticancéreux. / Epidermal growth factor receptor (EGFR) is a rational target for squamous cell carcinoma (SCC) anticancer therapies, nevertheless; only a subset of patients shows clinical benefits. I demonstrated a cooperation between EGFR signaling and extracellular matrix (ECM) stiffness that could explain this phenomenon. I sought to resolve the molecular pathway underlying this cooperation in SCC proliferation and expansion in order to identify new pharmaceutical targets. Screening of pharmacological inhibitors, in an in vitro 3-D assay, identified verapamil and diltiazem, FDA approved L-type calcium channels inhibitors, as potent blockers of SCC invasion. Mechanistically, I revealed that tumor-derived ECM stiffness and EGFR signaling trigger increased of intracellular calcium through the L-type CaV1.1 channel in SCC. Blocking L-type calcium channels activity resulted in reduced SCC cells invasion and proliferation in vitro. More importantly, I also demonstrate a strong reduction in tumor development in two in vivo models, both head and neck patient derived xenograft and skin SCC mice model. Consequently, I suggest a repurpose of verapamil and diltiazem to anti-cancer agents.

The epidermal growth factor receptor (EGFR)-K745_E746insIPVAIK and others with rare PVAI amino-acid insertions are exon 19 insertion mutations (<1% of all EGFR mutations), which, at the structural modeling level, resemble EGFR tyrosine kinase inhibitor (TKI)-sensitizing mutants. An important unmet clinical need is the characterization of therapeutic windows of rare exon 19 PVAI amino-acid insertions to available EGFR TKIs. A limited number of preclinical and clinical reports have studied the response of these mutants to all classes of approved EGFR TKIs. We used models of EGFR-K745_E746insIPVAIK and more typical EGFR mutations (exon 19 deletion, L858R, L861Q, G719S, A763_Y764insFQEA, other exon 20 insertion mutations) to probe representative 1st (erlotinib), 2nd (afatinib), 3rd generation (osimertinib), and EGFR exon 20 active (mobocertinib) TKIs. We used human lung-cancer derived cell lines and transduced Ba/F3 cells to measure the treatment efficacy. We also compiled outcomes of EGFR exon 19 insertion mutated lung cancers−from our institution plus the literature−treated with EGFR TKIs. Cells driven by EGFR-K745_E746insIPVAIK had sensitivity to all classes of EGFR TKIs when compared to cells driven by EGFR-wild type in proliferation assays and at the protein level. However, the therapeutic window (calculated in preclinical models as the logarithm of the 50% inhibitory concentration of EGFR mutation compared to wild-type EGFR) of EGFR-K745_E746insIPVAIK driven cells was most akin to those of cells driven by EGFR-L861Q, EGFR-G719S and EGFR- A763_Y764insFQEA than the more sensitive patterns seen with cells driven by an EGFR exon 19 deletion or EGFR-L858R. The majority of patients with lung cancers harboring EGFR- K745_E746insIPVAIK and other mutations with rare PVAI amino-acid insertions responded to clinically available EGFR TKIs (including icotinib, gefitinib, erlotinib, afatinib and osimertinib), with heterogeneous periods of progression-free survival. This is the largest preclinical/clinical report to highlight that EGFR- K745_E746insIPVAIK and other mutations with rare exon 19 PVAI amino-acid insertions are sensitive to clinically available TKIs; in a pattern that mostly resembles the outcomes of models with EGFR-L861Q, EGFR-G719S and EGFR-A763_Y764insFQEA mutations. These findings are consistent with the proposed mechanism of activation of mutant EGFR by alteration of the proposed hydrophobic core. These data may help with the off-label selection of EGFR TKIs and clinical expectations of outcomes when targeted therapy is deployed for these rare EGFR mutated lung cancers. / 2026-03-08T00:00:00Z

<p>The optimal way to detect and treat cancer is to target cancer cells exclusively without affecting the surrounding tissue. One promising approach is to use radiolabelled molecules to target receptors that are overexpressed in cancer cells. Since the epidermal growth factor receptor (EGFR) family is overexpressed in many types of cancer, it is an attractive target for both diagnostic and therapeutic applications.</p><p>This thesis can be divided into two parts. In part one (paper I), studies were conducted to modulate radionuclide uptake in tumour cells. The results showed that it was possible to modulate the cellular uptake of ¹²⁵I delivered by trastuzumab (targeting HER2) by adding EGF (targeting EGFR).</p><p>In part two (papers II-V) a high affinity EGFR-targeting affibody molecule (Z_EGFR:955)₂ was selected and analysed both <i>in vitro</i> and <i>in vivo</i>. In papers II, III and V, the results obtained when using (Z_EGFR:955)₂ were compared with those obtained with the two EGFR-binding molecules, EGF and cetuximab. These studies demonstrated that the affibody molecule bound specifically to EGFR (probably to subdomain III) with high affinity (~50 nM in biosensor analysis and ~1 nM in cellular studies) and produced intracellular signalling changes similar to those with cetuximab. In paper IV, <i>in vivo</i> studies were made, demonstrating that [¹¹¹In](Z_EGFR:955)₂ gave a tumour-specific ¹¹¹In uptake of 3.8±1.4% of injected dose per gram tumour tissue, 4 h post-injection. The tumours could be easily visualized with a gamma camera at this time-point. </p><p>The results of these studies indicated that the affibody molecule (Z_EGFR:955)₂ is a possible candidate for radionuclide-based imaging of EGFR-expressing tumours. The biological effects of (Z_EGFR:955)₂ might be of interest for therapy applications.</p>

Assessing hormone receptors (the estrogen and progesterone receptors) and the human epidermal growth factor receptor 2 (HER2) to guide clinical decision making revolutionized treatment for breast cancer patients. However, in the years since these biomarkers were first incorporated into routine clinical care, only a few others have been validated as clinically useful in guiding adjuvant chemotherapy decisions and are recommended by the American Society of Clinical Oncology (ASCO) for patients with hormone-positive breast cancer. For patients with triple-negative breast cancer (TNBC), which lacks hormone and HER2 receptors, not any of these biomarkers are recommended by ASCO due to insufficient evidence that they meaningfully improve clinical outcomes. Breast cancer is the second-leading cause of cancer-related death among women in the US, indicating an unmet need to improve treatments, which can be accomplished in part by identifying and validating novel predictive and prognostic biomarkers that yield actionable information about the clinical course of breast cancers, especially TNBCs. A major obstacle to improving outcomes for breast cancer patients is intratumor heterogeneity (ITH), which can be extensive in breast cancer and drives treatment resistance and relapse. I envision that assaying drivers of ITH can inform clinicians about which breast tumors may be intrinsically more aggressive and carry a greater risk of breast cancer-related morbidity and mortality. My research, presented here, primarily focuses on testing the impact of drivers of ITH (namely, centrosome amplification [CA], the clustering protein KIFC1, and mitotic propensity and its drivers) on clinical outcomes in breast cancer in multivariable models as well as the correlates of in vitro efficacy of centrosome declustering drugs (which can selectively eliminate cancer cells with CA). Collectively, these studies reveal gene signatures and immunohistochemical biomarkers that are independent predictors of aggressive breast cancer course and rational strategies to optimize targeted therapy to combat cancer cells exhibiting CA, thereby contributing to the literature on the development of precision medicine for breast cancer patients, including TNBC patients.

The human epidermal growth-factor like receptor (HER) family of receptor tyrosine kinases are important targets for cancer therapy. The family consists of four members - EGFR, HER2, HER3 and HER4 - that normally transfer stimulatory signals from extracellular growth factors to the intracellular signalling network. Over-activation of these receptors leads to uncontrolled cell proliferation and is seen in several types of tumours. The aim of the studies reported in this thesis was to study the uptake and effects of affibody molecules against EGFR, HER2 and HER3 in cultured cells. Affibody molecules are affinity proteins originally derived from one of the domains of protein A, and their small size and robust structure make them suitable agents for tumour targeting and therapy. Papers I and II of this thesis concern EGFR-specific affibody molecules, which were shown to be more similar to the antibody cetuximab than the natural ligand EGF in terms of cellular uptake, binding site and internalisation rate. In addition, fluorescence-based methods for the quantification of internalisation were evaluated. In the studies reported in papers III and IV, HER2-specific affibody molecules were utilised as carriers of radionuclides. Paper III reports that different cell lines exhibit different radiosensitivities to 211At-labelled affibody molecules; radiosensitivity was found to correlate with cell geometry and the rate of internalisation. Paper IV discusses the use of 17-AAG, an agent that induces HER2 internalisation and degradation, to force the internalisation of 211At- and 111In-labelled affibody molecules. Papers V and VI describe the selection and maturation of HER3-specific affibody molecules, which were found to compete with the receptor’s natural ligand, heregulin, for receptor binding. These affibody molecules were demonstrated to inhibit heregulin-induced HER3 activation and cell proliferation. The studies summarised in this paper will hopefully contribute to a better understanding of these affibody molecules and bring them one step closer to being helpful tools in the diagnosis and treatment of cancer.

p53 is mutated in 50% of all human cancers, and up to 70% of lung cancer. Mutant p53 is usually expressed at elevated levels in cancer cells and has been correlated with a poor prognosis. Cancer cells that express mutant p53 show an increase in oncogenic phenotypes including an increase in growth rate, resistance to chemotherapeutic drugs, and an increase in motility and tumorigenicity to name a few. We have identified several genes involved in cell growth and survival that are upregulated by expression of common p53 mutants: NFκB2, Axl, and epidermal growth factor receptor (EGFR). The aim of this study was to determine the role NFκB2, Axl, and EGFR play in mutant p53’s gain of function (GOF) phenotype and to determine a mechanism for upregulation of mutant p53 target gene upregulation. Inhibition of mutant p53 in various cancer cell lines using RNAi in the form of transient siRNA transfection or stable shRNA cell line generation caused a decrease in the gain of function ability of those cells in the form of reduced chemoresistance, reduced cell growth and motility, and a reduction in tumor formation. Additionally, inhibition of NFκB2, Axl, and EGFR also showed similar effects. Promoter deletion analysis of the NFκB2 promoter did not show a specific mutant p53 response element needed for mutant p53 mediated transactivation. Similarly, deletion of the p53/p63 binding site on the Axl promoter did not inhibit mutant p53 transactivation. Sequence analysis of the NFκB2, Axl, and EGFR promoters revealed several transcription factor binding sites located throughout the promoters. ChIP analysis of mutant p53 and the promoter-specific transcription factor binding revealed that in the presence of mutant p53, individual transcription factor binding is increased to the NFκB2, Axl, and EGFR promoters as well as an increase in acetylated histone binding. This data suggests that mutant p53 promotes an increase in transcription by inducing acetylation of histones via recruitment of transcription factors to the promoters of mutant p53 target genes.