O carcinoma epidermóide de cabeça e pescoço (CECP) representa 6ª malignidade mais comum no mundo. Para melhor entender os mecanismos envolvidos na iniciação tumoral, progressão e metástase, é necessária a elucidação dos eventos moleculares que guiam esses processos. É também importante a investigação da interação e modulação das células tumorais e seu microambiente. A participação de agentes inflamatórios no desenvolvimento e manutenção do CECP pode ser resumida na superexpressão da cicloxigenase 2 (COX-2) e na secreção de prostaglandina E2 (PGE2) pelas células tumorais. A PGE2 ativa seus receptores EP1-4 que são ligados a proteínas G. As proteínas G ativam outras vias de sinalização responsáveis por processos celulares como proliferação e angiogênese. Embora a participação do EP2 no câncer de cólon seja bem estabelecida, o papel dos receptores de PGE2 no CECP ainda permanece incerto. Este trabalho teve como objetivo avaliar o papel da PGE2 e de seus receptores na proliferação celular em linhagens celulares de CECP, bem como a expressão dos receptores em tissue microarrays de CECP. Inicialmente as linhagens de CECP foram utilizadas para analisar o padrão de expressão da COX-2 e dos receptores EP1-4 por meio da técnica de western blotting. A inibição da secreção da PGE2 pelos inibidores de COX-2 foi mensurada por meio da técnica de ELISA. A expressão dos receptores EP1-3 e da COX-2 foi também avaliada por meio da imuno-histoquímica em dois diferentes tissue microarray. A fim de esclarecer a indução da proliferação celular pela PGE2 e de apontar um de seus receptores como responsável pelo processo, duas PGE2 sintéticas, um antagonista do EP2 e um antagonista do EP3 foram utilizados para estimular a proliferação celular. Foi realizado o bloqueio do receptor EP2 por meio da interferência de RNA. Seus efeitos sobre a proliferação foram avaliados por meio do ensaio de incorporação de timidina. Os resultados mostraram que o CECP expressa constitutivamente a COX-2, o EP1, o EP2 e o EP3; e que é capaz de secretar PGE2. Os inibidores de COX-2 inibiram a secreção de PGE2 em baixas concentrações, mas não foram capazes de inibir a proliferação. A COX-2 e os receptores EP1-3 foram amplamente expressos nos tissue microarrays. Foi observada correlação entre EP1 e EP2; EP1 e EP3; e EP2 e EP3 (p<0,05). Somente o EP1 mostrou correlação com a COX-2 (p<0,05). A PGE2 induziu a proliferação por meio da indução da síntese de DNA nas linhagens celulares de CECP. O agonista de EP3 também induziu a síntese de DNA, sugerindo sua participação na proliferação dos CECPs. Os efeitos do siRNA para EP2 sobre a síntese de DNA não foram conclusivos. As proteínas ativadas por segundos mensageiros do EP2 também não foram afetadas pelo bloqueio do mesmo. Este estudo indica três importantes achados: 1. a PGE2 é secretada por linhagens de CECP; 2. a COX-2 é superexpressa nos CECPs; 3. os receptores de PGE2 são constitutivamente expressos nos CECPs. No entanto, esse trabalho mostra que esta via inflamatória parece ser independente aos mecanismos indutores da proliferação nos CECPs. / Head and neck squamous cell carcinoma (HNSCC) is the 6th most common malignant lesion worldwide. To better understand the mechanisms of tumor initiation, progression, and metastasis a better understanding of the molecular networks that guides these process is needed. Towards this goal, it is important to investigate the interaction and modulation of cancer cells over its surrounding microenvironment. The involvement of inflammatory agents in HNSCC development and maintenance can be resumed in the overexpression of cycloxygenase 2 (COX-2) and secretion of prostaglandin E2 (PGE2) by tumor cells. Prostaglandin E2 activates its receptors EP1-4 which are coupled to G proteins. G protein activates other pathways responsible for cellular processes such as proliferation and angiogenesis. The participation of EP2 in colon cancer is well established however the role of PGE2 receptors in HNSCC is still poorly understood. This work aims to investigate the role of PGE2 and its receptors in cellular proliferation in HNSCC cell lines and the clinical relevant expression pattern in HNSCC tissue microarrays. HNSCC cell lines were initially used to access the expression pattern of COX-2 and EP1-4 by using western blotting technique. The ability of selective COX-2 inhibition to block PGE2 secretion was measured by ELISA antibody specific assay. Also, EP1, EP2, EP3 and COX-2 expression were evaluated by immuno-histochemistry in two different sets of HNSCC tissue microarrays. To address the question about PGE2 inducted cell proliferation and which PGE2 receptor are involved in the process, two synthetic PGE2, an EP2 agonist and an EP3 agonist were used to stimulate cell proliferation. Finally, the knockdown of EP2 receptor was performed by siRNA transfection assay and its effect was evaluated in cell proliferation by radioactive thymidine incorporation assay. The results presented here shows that HNSCC constitutively express COX-2, EP1, EP2 and EP3 and that they are able to secret PGE2. COX-2 selective inhibitors are able to suppress PGE2 secretion in lower concentrations but not to inhibit cell proliferation. Also, COX-2, EP1, E2 and EP3 are widely expressed in HNSCC tissue microarrays. A correlation between EP1 and EP2; EP1 and EP3; and EP2 and EP3 (p<0.05) was observed. Only EP1 showed correlation with COX-2 in tissue microarrays (p<0,05). PGE2 was able to induce cell proliferation as it induces DNA synthesis in HNSCC cell lines. EP3 agonist also induced DNA synthesis addressing its role in cell proliferation induction in HNSCC. The siRNA for EP2 effects in DNA synthesis was not conclusive and the downstream proteins activated by EP2 second messenger were not affected following its expression knockdown. This study indicates three important findings. First, PGE2 is secreted by HNSCC. Second, COX-2 is found to be overexpressed in HNSCC; and third, PGE2 receptors are found to be constitutively expressed in HNSCC. Most interesting, we show here that this inflammatory pathway seems to be independent of the mechanisms that induce HNSCC proliferation.

It is estimated that nearly 50,000 individuals in the United States will be diagnosed with head and neck cancer in 2017 (American Cancer Society www.cancer.org). Ninety percent of oral cancers are head and neck squamous cell carcinoma (HNSCC). Major obstacles in the treatment of HNSCC are recurrence and treatment resistance, which contributes to increased mortality. Therefore, there is increased need to determine genetic alterations in HNSCC that may be ideal novel drug targets, and biomarkers to improve diagnostic and prognostic testing. Abnormal localization and overexpression of base excision repair protein and transcriptional regulator Apurinic/Apyrimidic endonuclease (APE1) has been associated with treatment resistance and poor prognosis. Therefore, we explored mechanisms for how APE1 contributes to treatment resistance and increased mortality in HNSCC. Because oxidative stress heavily influences APE1’s expression and transcriptional regulatory activities, we examined genes involved in oxidative stress management, including SOD3 and NRF2. PPARGC1A, a NRF2 transcriptional co-activator, was also examined as our lab previously observed a link between APE1 and PPARGC1A expression. This previous work also revealed that APE1 suppressed gene expression of tumor suppressor, decorin (DCN). To examine possible mechanisms for how APE1 regulates expression of tumor suppressors and antioxidants, digital image analysis of immunohistochemistry staining was used to identify alterations in protein expression. Nuclear and total cellular protein expression of APE1, DCN, NRF2, PPARGC1A, and SOD3 were quantified in regions of proximal benign, carcinoma in situ (CIS) and invasive HNSCC. Patient survival analysis revealed that increased APE1, DCN, and PPARGC1A protein levels were significantly associated with reduced survival in CIS, benign, and invasive tissues respectively. Using multivariate analysis of protein expression, we identified that increased APE1 protein levels in the CIS of primary tumors were associated with the presence of cancer invaded lymph nodes. Elevated DCN and SOD3 protein levels in benign tissue were associated with poorly differentiated tumors as was reduced PPARGC1A in CIS. Most importantly, potential prognostic biomarkers for use in early cancer development were identified. Identifying poor prognosis in early cancer development allows the possibility of improved treatment strategies, which could prevent invasive cancer development, and increase patient survival.

Câncer é a principal causa de morte nos países desenvolvidos e a segunda causa de morte nos países em desenvolvimento. O trabalho de diversos grupos de pesquisa tem sugerido que os tumores estão organizados em uma hierarquia de células, na qual uma pequena fração apresenta propriedades de células-tronco. Essas células tem se mostrado resistentes à quimioterapia convencional, dependentes da sinalização do microambiente tumoral e responsivas à terapia diferenciativa. Aqui nós mostramos que butirato sódico (NaB), um inibidor de desacetilase de histonas, diminui a proliferação celular e a formação de colônias em linhagens celulares de meduoblastoma humano. Estes efeitos foram acompanhados de um aumento da expressão de RNAm Gria2, um marcador de diferenciação neuronal, em duas das três linhagens celulares testadas. A formação de neuroesferas também foi impedida com a exposição de uma linhagem crescida em meio de cultura apropriado para células-tronco e NaB. NaB se mostrou capaz de potencializar os efeitos do quimioterápico etoposídeo e do fator neurotrófico derivado de cérebro (BDNF) na inibição da viabilidade celular de meduloblastoma. Além disso, nós observamos que o tratamento com cisplatina aumenta a proporção de células-tronco tumorais (CTT), identificadas por ALDH+CD44+, em células de carcinoma de cabeça e pescoço, quando tratadas também com interleucina 6 (IL-6), uma citocina liberada pelo nicho perivascular. O mesmo tratamento promoveu a proliferação, sobrevivência e auto-renovação de CTTs in vitro ao aumentar o número de esferas em placas de baixa aderência e a expressão de Bmi-1 em western blots. A fosforilação do transdutor de sinal e ativador de transcrição 3 (STAT3), um indicativo de propriedades de CTTs, induzida por IL-6 não foi afetada pelo tratamento com cisplatina em células de HNSCC, enquanto que a indução de fosforilação de quinases reguladas por sinais extracelulares (ERK), indicativo de processo de diferenciação, por IL-6 foi parcialmente inibido por cisplatina. Células resistentes a baixas doses de cisplatina também expressaram mais Bmi-1 do que células nunca expostas ao quimioterápico. Experimentos in vivo corroboram os achados in vitro, uma vez que tumores humanos induzidos em camundongos imunocomprometidos apresentaram aumentada proporção de células ALDH+CD44+ após tratamento dos animais com cisplatina. O anticorpo contra o receptor de IL-6 foi capaz de reverter a indução de expressão de Bmi-1 por cisplatina e IL-6. Em conjunto, esses resultados sugerem que a modulação de mecanismos epigenéticos das células tumorais e de sinais provenientes do nicho tumoral são novos alvos promissores para o desenvolvimento de terapias adjuvantes contra o câncer. / Cancer is the leading cause of death in economically developed countries and the second cause of death in developing countries. Work from a number of laboratories strongly suggests that tumors are organized as a hierarchy based on a subset of cancer cells that have stem-cell properties. These cells have been shown to be resistant to conventional therapy, dependent on contextual signals within the tumor microenvironment and, to be responsive to differentiation therapy. Here we show that sodium butyrate (NaB), a histone deacetylase inhibitor, decreases cell proliferation and colony formation in human medulloblastoma cell lines. These effects were accompanied by an increased mRNA expression of Gria2, a neuronal differentiation marker, in two out of three cell lines tested. In addition, neurosphere formation was impaired by NaB exposure in a cell line submitted to stem cells proper media. NaB also may potentiate the effect of etoposide chemotherapy and BDNF (Brain-derived neurotrophic factor) on the inhibition of medulloblastoma cells viability. Moreover, we observed that cisplatin treatment increased the proportion of cancer stem cells (CSC), identified by ALDHhighCD44high cells, in head and neck squamous cell carcinoma (HNSCC), when treated together with recombinant human IL-6 (rhIL-6). The same regimen promoted proliferation, self-renewal and survival of CSC in vitro as seen by the increase in orosphere number formed in ultra-low attachment plates, and Bmi-1 expression induction in western blots. IL-6–induced signal transducer and activator of transcription 3 (STAT3) phosphorylation (indicative of stemness) was unaffected by treatment with cisplatin in HNSCC cells, whereas IL-6–induced extracellular signal-transducer kinases (ERK) phosphorylation (indicative of differentiation processes) was partially inhibited by cisplatin. Cells resistant to lower doses of cisplatin also expressed more Bmi-1. In vivo experiments corroborated in vitro findings by showing increased proportion of ALDH highCD44high cells in xenograft tumors of mice treated with cisplatin. An antibody against the receptor of IL-6 was able to revert the induction of Bmi-1 expression seen in cells treated with cisplatin plus IL-6. Taken together, these results suggest that the modulation of the epigenetic states of the cancer cell and modulation of signals provided by the niche are promising new molecular targets for the development of adjuvant therapy for cancer.

Head and neck squamous cell carcinoma is the fifth most common cancer worldwide. They are associated with high morbidity and mortality. Despite considerable advances in surgical and oncological treatment over the past two decades, overall treatment outcome has only slightly improved. In my thesis I focused on serum gene expression analysis of head and neck cancer patients, which followed the tissue gene expression analysis in same patients. Further we investigated gene expression analysis in tumour stroma, which is now considered as significant factor in cancer initiation and progression. We revealed several candidate genes, which are involved in signalling pathways connected with cell differentiation and proliferation and are involved in apoptotic pathway (BCl-2, BCl-XL a MAX). As well we detected down-regulation of the main tumour suppressor p 53 protein. In peritumoural tissue we detected overexpression of cytokines typical for embryonal development and ectoderm differentiation - IGF-2 and BMP-4, which significantly influence the phenotype of normal keratinocytes. Further we identified several candidate genes relating with overexpression of Gal-1 in stromal myofibroblasts rich tissue (SPIN1, FUSIP1, TRIM23, SLC25A40, PTPLAD1, MP3K2). HNSCC is a heterogeneous disease despite the presence of...

Câncer é a principal causa de morte nos países desenvolvidos e a segunda causa de morte nos países em desenvolvimento. O trabalho de diversos grupos de pesquisa tem sugerido que os tumores estão organizados em uma hierarquia de células, na qual uma pequena fração apresenta propriedades de células-tronco. Essas células tem se mostrado resistentes à quimioterapia convencional, dependentes da sinalização do microambiente tumoral e responsivas à terapia diferenciativa. Aqui nós mostramos que butirato sódico (NaB), um inibidor de desacetilase de histonas, diminui a proliferação celular e a formação de colônias em linhagens celulares de meduoblastoma humano. Estes efeitos foram acompanhados de um aumento da expressão de RNAm Gria2, um marcador de diferenciação neuronal, em duas das três linhagens celulares testadas. A formação de neuroesferas também foi impedida com a exposição de uma linhagem crescida em meio de cultura apropriado para células-tronco e NaB. NaB se mostrou capaz de potencializar os efeitos do quimioterápico etoposídeo e do fator neurotrófico derivado de cérebro (BDNF) na inibição da viabilidade celular de meduloblastoma. Além disso, nós observamos que o tratamento com cisplatina aumenta a proporção de células-tronco tumorais (CTT), identificadas por ALDH+CD44+, em células de carcinoma de cabeça e pescoço, quando tratadas também com interleucina 6 (IL-6), uma citocina liberada pelo nicho perivascular. O mesmo tratamento promoveu a proliferação, sobrevivência e auto-renovação de CTTs in vitro ao aumentar o número de esferas em placas de baixa aderência e a expressão de Bmi-1 em western blots. A fosforilação do transdutor de sinal e ativador de transcrição 3 (STAT3), um indicativo de propriedades de CTTs, induzida por IL-6 não foi afetada pelo tratamento com cisplatina em células de HNSCC, enquanto que a indução de fosforilação de quinases reguladas por sinais extracelulares (ERK), indicativo de processo de diferenciação, por IL-6 foi parcialmente inibido por cisplatina. Células resistentes a baixas doses de cisplatina também expressaram mais Bmi-1 do que células nunca expostas ao quimioterápico. Experimentos in vivo corroboram os achados in vitro, uma vez que tumores humanos induzidos em camundongos imunocomprometidos apresentaram aumentada proporção de células ALDH+CD44+ após tratamento dos animais com cisplatina. O anticorpo contra o receptor de IL-6 foi capaz de reverter a indução de expressão de Bmi-1 por cisplatina e IL-6. Em conjunto, esses resultados sugerem que a modulação de mecanismos epigenéticos das células tumorais e de sinais provenientes do nicho tumoral são novos alvos promissores para o desenvolvimento de terapias adjuvantes contra o câncer. / Cancer is the leading cause of death in economically developed countries and the second cause of death in developing countries. Work from a number of laboratories strongly suggests that tumors are organized as a hierarchy based on a subset of cancer cells that have stem-cell properties. These cells have been shown to be resistant to conventional therapy, dependent on contextual signals within the tumor microenvironment and, to be responsive to differentiation therapy. Here we show that sodium butyrate (NaB), a histone deacetylase inhibitor, decreases cell proliferation and colony formation in human medulloblastoma cell lines. These effects were accompanied by an increased mRNA expression of Gria2, a neuronal differentiation marker, in two out of three cell lines tested. In addition, neurosphere formation was impaired by NaB exposure in a cell line submitted to stem cells proper media. NaB also may potentiate the effect of etoposide chemotherapy and BDNF (Brain-derived neurotrophic factor) on the inhibition of medulloblastoma cells viability. Moreover, we observed that cisplatin treatment increased the proportion of cancer stem cells (CSC), identified by ALDHhighCD44high cells, in head and neck squamous cell carcinoma (HNSCC), when treated together with recombinant human IL-6 (rhIL-6). The same regimen promoted proliferation, self-renewal and survival of CSC in vitro as seen by the increase in orosphere number formed in ultra-low attachment plates, and Bmi-1 expression induction in western blots. IL-6–induced signal transducer and activator of transcription 3 (STAT3) phosphorylation (indicative of stemness) was unaffected by treatment with cisplatin in HNSCC cells, whereas IL-6–induced extracellular signal-transducer kinases (ERK) phosphorylation (indicative of differentiation processes) was partially inhibited by cisplatin. Cells resistant to lower doses of cisplatin also expressed more Bmi-1. In vivo experiments corroborated in vitro findings by showing increased proportion of ALDH highCD44high cells in xenograft tumors of mice treated with cisplatin. An antibody against the receptor of IL-6 was able to revert the induction of Bmi-1 expression seen in cells treated with cisplatin plus IL-6. Taken together, these results suggest that the modulation of the epigenetic states of the cancer cell and modulation of signals provided by the niche are promising new molecular targets for the development of adjuvant therapy for cancer.

Câncer é a principal causa de morte nos países desenvolvidos e a segunda causa de morte nos países em desenvolvimento. O trabalho de diversos grupos de pesquisa tem sugerido que os tumores estão organizados em uma hierarquia de células, na qual uma pequena fração apresenta propriedades de células-tronco. Essas células tem se mostrado resistentes à quimioterapia convencional, dependentes da sinalização do microambiente tumoral e responsivas à terapia diferenciativa. Aqui nós mostramos que butirato sódico (NaB), um inibidor de desacetilase de histonas, diminui a proliferação celular e a formação de colônias em linhagens celulares de meduoblastoma humano. Estes efeitos foram acompanhados de um aumento da expressão de RNAm Gria2, um marcador de diferenciação neuronal, em duas das três linhagens celulares testadas. A formação de neuroesferas também foi impedida com a exposição de uma linhagem crescida em meio de cultura apropriado para células-tronco e NaB. NaB se mostrou capaz de potencializar os efeitos do quimioterápico etoposídeo e do fator neurotrófico derivado de cérebro (BDNF) na inibição da viabilidade celular de meduloblastoma. Além disso, nós observamos que o tratamento com cisplatina aumenta a proporção de células-tronco tumorais (CTT), identificadas por ALDH+CD44+, em células de carcinoma de cabeça e pescoço, quando tratadas também com interleucina 6 (IL-6), uma citocina liberada pelo nicho perivascular. O mesmo tratamento promoveu a proliferação, sobrevivência e auto-renovação de CTTs in vitro ao aumentar o número de esferas em placas de baixa aderência e a expressão de Bmi-1 em western blots. A fosforilação do transdutor de sinal e ativador de transcrição 3 (STAT3), um indicativo de propriedades de CTTs, induzida por IL-6 não foi afetada pelo tratamento com cisplatina em células de HNSCC, enquanto que a indução de fosforilação de quinases reguladas por sinais extracelulares (ERK), indicativo de processo de diferenciação, por IL-6 foi parcialmente inibido por cisplatina. Células resistentes a baixas doses de cisplatina também expressaram mais Bmi-1 do que células nunca expostas ao quimioterápico. Experimentos in vivo corroboram os achados in vitro, uma vez que tumores humanos induzidos em camundongos imunocomprometidos apresentaram aumentada proporção de células ALDH+CD44+ após tratamento dos animais com cisplatina. O anticorpo contra o receptor de IL-6 foi capaz de reverter a indução de expressão de Bmi-1 por cisplatina e IL-6. Em conjunto, esses resultados sugerem que a modulação de mecanismos epigenéticos das células tumorais e de sinais provenientes do nicho tumoral são novos alvos promissores para o desenvolvimento de terapias adjuvantes contra o câncer. / Cancer is the leading cause of death in economically developed countries and the second cause of death in developing countries. Work from a number of laboratories strongly suggests that tumors are organized as a hierarchy based on a subset of cancer cells that have stem-cell properties. These cells have been shown to be resistant to conventional therapy, dependent on contextual signals within the tumor microenvironment and, to be responsive to differentiation therapy. Here we show that sodium butyrate (NaB), a histone deacetylase inhibitor, decreases cell proliferation and colony formation in human medulloblastoma cell lines. These effects were accompanied by an increased mRNA expression of Gria2, a neuronal differentiation marker, in two out of three cell lines tested. In addition, neurosphere formation was impaired by NaB exposure in a cell line submitted to stem cells proper media. NaB also may potentiate the effect of etoposide chemotherapy and BDNF (Brain-derived neurotrophic factor) on the inhibition of medulloblastoma cells viability. Moreover, we observed that cisplatin treatment increased the proportion of cancer stem cells (CSC), identified by ALDHhighCD44high cells, in head and neck squamous cell carcinoma (HNSCC), when treated together with recombinant human IL-6 (rhIL-6). The same regimen promoted proliferation, self-renewal and survival of CSC in vitro as seen by the increase in orosphere number formed in ultra-low attachment plates, and Bmi-1 expression induction in western blots. IL-6–induced signal transducer and activator of transcription 3 (STAT3) phosphorylation (indicative of stemness) was unaffected by treatment with cisplatin in HNSCC cells, whereas IL-6–induced extracellular signal-transducer kinases (ERK) phosphorylation (indicative of differentiation processes) was partially inhibited by cisplatin. Cells resistant to lower doses of cisplatin also expressed more Bmi-1. In vivo experiments corroborated in vitro findings by showing increased proportion of ALDH highCD44high cells in xenograft tumors of mice treated with cisplatin. An antibody against the receptor of IL-6 was able to revert the induction of Bmi-1 expression seen in cells treated with cisplatin plus IL-6. Taken together, these results suggest that the modulation of the epigenetic states of the cancer cell and modulation of signals provided by the niche are promising new molecular targets for the development of adjuvant therapy for cancer.

Les carcinomes épidermoïdes des voies aéro-digestives supérieures (VADS) se situent au sixième rang des cancers les plus fréquents dans le monde. Ces tumeurs sont liés à deux facteurs de risque : l’intoxication éthylo-tabagique (80% des cas) et l’infection de l’épithélium des VADS par les papillomavirus humain (HPV) à haut risque oncogène (20% des cas). Ces derniers définissent une sous-population de patients de meilleur pronostic. Une des hypothèses actuellement étudiées, afin d’expliquer la survie améliorée des patients HPV positifs, serait une hypoxie moindre dans ces tumeurs. En effet, les tumeurs des VADS sont fréquemment hypoxiques, et l’hypoxie intratumorale est un facteur de mauvais pronostic. Dans une première partie de cette thèse, nous avons entrepris une caractérisation moléculaire de l’hypoxie intratumorale dans les tumeurs humaines oropharyngées en fonction du statut HPV. Il apparaît que les tumeurs HPV positives présentent un statut hypoxique moindre comparées aux tumeurs HPV négatives. Ces tumeurs se caractérisent également par une abondante vascularisation intratumorale, qui pourrait être à l’origine de ce statut hypoxique moindre. Dans une deuxième partie, nous avons étudié l’adaptation à l’hypoxie de la lignée cellulaire HPV négative SQ20B et la lignée cellulaire HPV positive SCC90. De plus, des modèles de xénogreffes ont été établis à partir de ces mêmes lignées cellulaires et ont été analysés du point de vue de l’hypoxie intratumorale. De façon comparable aux tumeurs HPV positives, les xénogreffes obtenus à partir de la lignée SCC90 montre un statut hypoxique réduit comparés aux xénogreffes SQ20B. Les deux lignées cellulaires s’adaptent également différemment en hypoxie in vitro. La réponse à l’hypoxie dans la lignée SCC90 semble plus dynamique. En effet, la lignée SCC90 tente de s’adapter et de répondre à cet environnement hypoxique en induisant de fort niveau d’expression de gènes comparée à la lignée SQ20B. / Head and neck squamous cell carcinoma (HNSCC) represents the sixth most common malignancy worldwide. The major risk factors for HNSCC identified are tobacco use and alcohol consumption (80% of all HNSCC), which seem to have a synergistic effect. A subgroup of HNSCCs (20% of cases), particularly those of the oropharynx, is caused by infection with high-risk types of human papillomavirus (HPV). Human papillomavirus HPV-related oropharyngeal squamous cell carcinoma defines a distinct clinical subgroup of head and neck cancer patients with improved prognosis. Currently, one of the several hypothesis studied to account for their improved survival outcomes could be a distinct hypoxia status compared to their HPV-negative counterpart. Indeed, tumour hypoxia is common in solid tumours including head and neck tumours, and hypoxia is a well-known poor prognosis factor. In first part of this thesis, we have performed a molecular characterisation of tumor hypoxia on cohort of oropharyngeal tumours according to HPV status of the patients. The results support the hypothesis that HPV-related tumours display a lesser hypoxia status compared to HPV-negative oropharyngeal tumours. These HPV-related tumours also characterize by an abundant tumour vascularisation, which could be responsible for a lesser hypoxia status. In a second part, we have studied the ability of the adaptation to hypoxia of the HPV-positive SCC90 cell line and HPV-negative SQ20B cell line. Furthermore, HPV-positive and HPV-negative HNSCC xenograft models have been established and have been analysed about tumor hypoxia. Similar to HPV-related HNSCC, tumours-derived HPV positive cell lines display a reduced hypoxic status compared to tumours-derived HPV negative cell lines. The two cell lines adapt also differently to in vitro hypoxia. In the HPV-positive cell line, the hypoxia response pathways could be more dynamics. Indeed, SCC90 cell lines attempt to adapt and to reply to hypoxic environment inducing highly expression of all of the hypoxia related genes compared to SQ20B cell lines.

Head and neck squamous cell carcinoma is the fifth most common cancer worldwide. They are associated with high morbidity and mortality. Despite considerable advances in surgical and oncological treatment over the past two decades, overall treatment outcome has only slightly improved. In my thesis I focused on serum gene expression analysis of head and neck cancer patients, which followed the tissue gene expression analysis in same patients. Further we investigated gene expression analysis in tumour stroma, which is now considered as significant factor in cancer initiation and progression. We revealed several candidate genes, which are involved in signalling pathways connected with cell differentiation and proliferation and are involved in apoptotic pathway (BCl-2, BCl-XL a MAX). As well we detected down-regulation of the main tumour suppressor p 53 protein. In peritumoural tissue we detected overexpression of cytokines typical for embryonal development and ectoderm differentiation - IGF-2 and BMP-4, which significantly influence the phenotype of normal keratinocytes. Further we identified several candidate genes relating with overexpression of Gal-1 in stromal myofibroblasts rich tissue (SPIN1, FUSIP1, TRIM23, SLC25A40, PTPLAD1, MP3K2). HNSCC is a heterogeneous disease despite the presence of...

No description available.

Squamous cell carcinoma is the most frequent malignant tumour of head and neck. Prognostic and predictive information as an individual imprint of molecular-genetic analysis of HNSCC will help to determine the best indivicual treatment. And in case of surgical appraoch the optimal resection with adequate quality of life and long-term survival. Study of early cancerogenesis in our project is based on knowledge, that histological normal mucosa next to tumor shows preneoplastic molecular alterations. Molecular genetic changes in a histological normal mucosa harbouring a tumor may play a principal role in revealing of early cancerogenesis process. Molecular-genetic analysis of cancerogenesis in HNSCC reveals prognostic and predictive factors, which are necessary for evaluation and decission for the best individual treatment. This is the concept of tailored medicine The text summarizes current knowledge of early cancerogenesis in HNSCC and presents molecular-biological trends, which are necessary to discover details of early cancerogenesis and thus to get a tool for better detection as well as treatment of malignant disease. The study is based on fragment analysis of microsatelites lesions in tumor tissue in comparison to adjacent mucosa and the healthy mucosa. Results show significant molecular-biological...