Cancer is a stem cell disease and populations of cancer stem cells (CSCs) are evident in many cancer types. CSCs exhibit similarities to normal embryonic and adult stem cells: they are able to self-renew and have the potential to give rise to a diverse array of differentiated progeny. CSCs are responsible for driving tumourigenesis and metastasis, and are inherently resistant to chemotherapy and radiotherapy. This cell population is enriched after treatment and, as a result of their tumourigenic capability, can re-populate tumour growth resulting in patient relapse, often with increased chemotherapeutic resistance. Increasing evidence supports that only by targeting this population of cells will a cure for cancer be possible. Hence, it is essential to identify pathways within CSC populations that can be targeted therapeutically. Cyclooxygenase-2 (COX-2) is an enzyme associated with inflammation and disease, and is upregulated in many cancers types. The COX-2 / prostaglandin E2 (PGE2) signalling pathway is associated with increased tumour growth, metastasis, immune evasion and overall worse patient prognosis. Recent evidence has identified that COX-2 is further upregulated in CSC populations isolated from cancer cell lines. Previously, we have shown that inhibition of COX-2 reduces CSC sphere-forming ability, a characteristic of stem cell self-renewal, suggesting a role for COX-2 in maintaining CSC populations. This work was carried out in both human and canine osteosarcoma cell lines with similar results. Cancer in dogs is a major health concern among an aging pet population. Many cancer types exhibit similarities between these species, suggesting that naturally occurring canine cancer may be a potential model for the human disease. The aim of this PhD project was to investigate the role of COX-2 in CSCs in a comparative cancer study. CSCs that express stem cell markers have been isolated from a panel of canine and human cancer cell lines including, mammary carcinoma and transitional cell carcinoma of the urinary bladder. CSCs over-express COX-2 compared to non-CSCs, therefore to determine the role of COX-2 in CSC biology the selective COX-2 inhibitor mavacoxib, a non-steroidal anti-inflammatory drug currently licenced for treating osteoarthritis in dogs, was utilised. Our results demonstrate that inhibiting COX-2 has a multifaceted impact on CSC biology, including reducing self-renewal capacity, clonogenicity, proliferation, migration, invasion and in vivo tumourigenicity. To confirm that mavacoxib is mediating these CSC-specific effects via inhibition of COX-2 rather than through unknown off-target effects, we generated canine specific-small interfering RNA to specifically reduce gene expression of COX-2. Our results confirm that mavacoxib exerts its anti-tumour effects via inhibition of COX-2. This project has highlighted a plethora of CSC-specific COX-2 effects, and to gain further insight we compared the global gene expression profiles of CSCs compared to non- CSCs isolated from a canine bladder carcinoma cell line. This data revealed that both mavacoxib and COX-2 specific siRNA target similar pathways within the two cell populations, confirming that mavacoxib exerts its effects in a COX-2 dependent manner. Interestingly, mavacoxib reduced the expression of a number of stemness related genes in the CSC population, including NOTCH and Wnt, suggesting that mavacoxib can inhibit CSC related pathways. Our overall results are comparable between canine and human cancer cell lines supporting the concept of naturally occurring tumours in dogs as models for the human disease. In conclusion, COX-2 plays an important role not only in maintaining CSC populations but also in their function, and targeting COX-2 in CSCs may provide therapeutic benefit.

Abdominal aortic aneurysm (AAA) is a chronic inflammatory disease with no available pharmacological treatment. AAA formation reduces the structural integrity of the vessel and increases the susceptibility to rupture. The inflammatory response within human aneurysmal tissue is characterized by increased expression of cyclooxygenase-2 (COX-2). Similarly, in a mouse model of the disease induced by chronic Angiotensin II (AngII) infusion, we have shown that COX-2 expression in the abdominal aortic smooth muscle layer increases early in the development of the disease. Furthermore, genetic or pharmacological inactivation of COX-2 prior to disease initiation reduces AAA incidence. The current study utilized nonhyperlipidemic mice to determine the effectiveness of COX-2 inhibition initiated after AAA formation. COX-2 inhibitor treatment was initiated 5 days after beginning the AngII infusion, a time-point where significant aneurysmal pathology is observed. COX-2 inhibition with celecoxib significantly reduced the incidence as well as severity of AAAs as compared to the control group. Celecoxib treatment also protected the mice from aortic rupture and death. AAA development is characterized by degradation of the aortic smooth muscle layer with loss of the contractile phenotype. We found that the effectiveness of celecoxib was associated with significantly increased mRNA expression of alpha-actin, SM22alpha and desmin, all of which are markers of a differentiated smooth muscle cell phenotype. Celecoxib treatment also decreased mRNA expression of a marker of dedifferentiated smooth muscle (hyaluronic acid synthase 2). We also examined the role of altered expression of COX-2 in the increased susceptibility of the abdominal segment to AAA formation. We found a prolonged and greater induction of COX-2 in the abdominal aortic smooth muscle layer in contrast to a transient induction of COX-2 in the other regions of the aorta throughout disease progression. Overall, these findings suggest that COX-2 plays an important role in AAA development in mice, and COX-2 inhibition with celecoxib attenuates progression of aneurysm development by maintaining a differentiated phenotype in abdominal aortic smooth muscle cells.

No description available.

Abstract Background and aims: Stage and grade are the most widely used prognostic parameters for renal cell carcinoma (RCC). The clinical course of this disease is not, however, always predictable by traditional prognostic factors. In the era of new molecular targeted therapies a more accurate prognostication of RCC patient survival is important for the individualization of treatment and follow-up of patients. Despite exhaustive research there are still no prognostic biomarkers for RCC in clinical practice. In order to find novel prognostic tissue markers for RCC, we examined the expression of 14 biomarkers involved in carcinogenesis and clarified their prognostic significance in RCC. Material and methods: Out of 189 consecutive patients who underwent surgery for kidney cancer at Oulu University Hospital in the 1990s, 152 patients with histologically verified RCC were included in this study. The stage distribution was 70 (46%), 12 (8%), 51 (34%) and 19 (12%) patients with stages I-IV, respectively. The majority of the tumours (83 tumours, 55%) were nuclear grade II and 5 (3%), 40 (27%) and 22 (15%) of the tumours were grades I, III and IV, respectively. Clinical and follow-up data were obtained from patient records, the Finnish Cancer Registry and on demand from the Population Register Centre of Finland. The biomarkers studied included markers of the oxidative and neuroendocrine systems as well as proteins related to cell adhesion and migration, invasion, metastasis, inflammation and immune responses. The expression of various biomarkers was characterized via immunohistochemical tests of archival tumour material. The staining intensity was compared to clinicopathological parameters and patient RCC-specific survival. Results: The 5-year RCC-specific survival was 77%. The expression of Toll-like receptor 9 (TLR9) was an independent marker of favourable RCC-specific survival whereas cytoplasmic myosin VI expression was found to be an independent prognostic factor of poor RCC-specific survival. Cell culture experiments showed how cyclooxygenase-2 (COX-2) expression is regulated by HuR in RCC. HuR and COX-2 immunoexpression were also related to decreased RCC-specific survival. Immunostaining of Keap1 was associated with advanced RCC and a marker of a poorer RCC-specific prognosis. The expression of different neuroendocrine markers was evaluated but we could not establish any prognostic value for them. Conclusions: In particular, TLR9, HuR and myosin VI can be regarded as promising novel prognostic biomarkers in RCC. Stage, however, is the most important single prognostic factor for RCC. / Tiivistelmä Munuaissyöpä on vuosikymmenten ajan jatkuvasti yleistynyt. Vaikka se diagnosoidaan nykyisin useimmiten sattumalöydöksenä vatsan alueen kuvantamistutkimuksissa ja hoitomenetelmät ovat viime vuosikymmenten aikana kehittyneet, munuaissyöpäkuolleisuus ei ole laskenut. Munuaissyövän ennusteen määrittäminen voi olla haasteellista. Perinteiset ennustetekijät, levinneisyys ja erilaistumisaste, eivät riitä selittämään kaikkien potilaiden taudinkulkua, eikä munuaissyövälle vielä ole kliinisessä käytössä ennusteellista merkkiainetta. Munuaissyöpähoitojen kehittyessä taudinkulun ennustaminen on yhä tärkeämpää, jotta potilaiden hoito ja seuranta voidaan yksilöidä. Tämän väitöskirjatyön tarkoituksena oli etsiä uusia ennusteellisia kudosmerkkiaineita munuaissyöpäkasvaimille. Väitöskirjatutkimus perustuu 1990-luvulla Oulun yliopistollisessa sairaalassa leikatun 152 munuaissyöpäpotilaan aineistoon. Lähes puolet aineiston kasvaimista edusti levinneisyysluokkaa I, ja yli puolet munuaissyöpäkasvaimista oli hyvin erilaistuneita (tumagradus I ja II). Tutkimuspotilaista kerättiin kattavat seurantatiedot. Leikkauksessa poistettujen munuaissyöpäkasvainten arkistomateriaalista tutkittiin eri merkkiaineiden ilmenemistä. Tutkitut merkkiaineet käsittivät oksidatiivisen ja neuroendokriinisen järjestelmän merkkiaineita sekä valkuaisaineita, jotka liittyvät keskeisiin syövän ominaisuuksiin, kuten solujen välisiin liitoksiin ja solujen liikkumiseen sekä etäpesäkkeiden syntymiseen. Lisäksi tutkittiin merkkiaineita, jotka liittyvät tulehdusreaktioihin ja immuunipuolustukseen. Väitöskirjatutkimus paljasti useita uusia kudosmerkkiaineita, joiden ilmeneminen munuaissyöpäkasvaimessa on yhteydessä potilaan ennusteeseen. Näistä merkittävimpiä ovat myosiini VI, joka liittyy syöpäkasvainten metastasointiin, sekä immuunipuolustuksessa vaikuttava Tollin kaltainen reseptori 9 (Toll-like receptor 9, TLR9). Molemmat merkkiaineet osoittautuivat itsenäisiksi ennustetekijöiksi munuaissyövässä. Muita ennusteeseen vaikuttavia merkkiaineita ovat tutkimuksen mukaan oksidatiivista stressiä aistiva Keap1 sekä immunologisiin reaktioihin liittyvä syklo-oksigenaasi 2 (COX-2) ja sen ilmenemistä säätelevä HuR.