Pancreatic cancer (PDAC) affects 4400 Canadians each year and with 5year survival rates <8%, there is clearly an unmet need for new therapeutic approaches for treating this deadly disease. Herein I report the development of a surgical model of PDAC that recapitulates many of the hallmarks of human disease and has an immune infiltrate consisting of T cells and suppressive regulatory T cells and myeloid derived suppressor cells. This model allows the exploration of new therapeutics that can be used in combination with surgical resection of primary tumours. Furthermore, I propose that the use of neoadjuvant administration of a prime-boost oncolytic vaccine targeting a pancreatic tumour associated antigen (TAA) - mesothelin - could potentiate pancreatic tumour specific immune responses to improve patient prognosis. We demonstrate that immune tolerance to this self antigen can be broken by the complete depletion of circulating Tregs at the time of vaccination, which leads to the activation of a population of CD8+ T cells responsive to mesothelin. We demonstrate that these T cells respond to mesothelin expressing tumour cells ex vivo, and that CD8+ T cells are recruited to the site of tumour challenge. However, despite the generated CD8+ T cell response, oncolytic vaccine strategies targeting mesothelin provide no protection against Pan02 tumours, or against other mesothelin expressing murine tumour lines. I demonstrate that this is not through common tumour escape mechanisms, nor through the upregulation of suppressive immune populations. Any efficacy observed was found to be provided solely by depletion of Tregs, as the depletion of CD8+ T cells did not reduce protection from tumour outgrowth in vaccinated mice. While mesothelin represents a promising target, it is not an ideal target for oncolytic vaccine platforms, potentially due to its nature as a self antigen.

Abstract Acute infected necrotizing pancreatitis (ANP) is a very complex disease with a high risk of complications and death. ANP is difficult to treat and is often associated with poor outcomes. Despite the increasing data on the technical details required to perform a mini-invasive necrosectomy for walled-off necrosis (WON), relatively few studies have focused on the presence and consequences of pancreatic duct disruption in the context of APN. Moreover, the long-term prognosis of patients with acute pancreatitis (AP) is scant. The aim of this study was to examine the diagnosis, treatment and prophylaxis of pancreatic fistulas (PFs) associated with APN. In addition, the long-term prognosis of AP was evaluated. The study population consists of the patients with AP treated at Oulu University Hospital, Finland (Studies I–IV) and Copenhagen University Hospital, Denmark (Study II) during 1995–2015. In the first part of the study, all consecutive patients following open necrosectomy for infected ANP were demonstrated to have PF. Endoscopic transpapillary pancreatic stenting (ETPS) was attempted and proven to be an effective and safe treatment for patients with PF. In Study II, prophylactic pancreatic stenting in the early stage of the disease was tested in a randomized controlled trial to the patients with ANP to prevent PFs associated with the disease. However, the study showed that the patients with ANP did not benefit from early prophylactic pancreatic ductal stenting (PPDS); instead, it seemed to be harmful for the patients. The results of Study III showed that single drain amylase level measurement after surgical necrosectomy is unreliable. According to this study, serial measurements are recommended to diagnose PFs after necrosectomy. Study IV including 1644 patients showed that AP, especially alcohol AP, was associated with a high long-term mortality. On the other hand, AP without an alcohol aetiology had a minimal impact on survival. In conclusion, in patients with infected ANP, a PF has to be considered in treatment, but the prevention of ductal leak with PPDS is not recommended. In addition, the poor long-term outcome among alcohol AP patients was due to alcohol-related diseases. / Tiivistelmä Akuutti nekrotisoiva haimatulehdus ja erityisesti siihen liittyvä bakteeri-infektio on sairaus, johon liittyy korkea komplikaatio- ja kuolleisuusriski. Tautia usein komplisoi infektion lisäksi nekroosiin liittyvä haimafisteli, joka tekee hoidosta entistä haasteellisemman. Viime aikaisissa tutkimuksissa on käsitelty runsaasti mini-invasiivista nekrosektomiaa, mutta suhteellisen vähän on tutkimuksia nekrotisoivaan haimatulehdukseen liittyvästä fisteliongelmasta. Haimatulehdus-potilaiden pitkäaikaisennuste on myös epäselvä. Tämän väitöskirjatutkimuksen tavoitteena oli selvittää nekrotisoivaan haimatulehdukseen liittyvän haimafistelin yleisyyttä, diagnostiikkaa, ehkäisyä ja hoitoa. Lisäksi tarkasteltiin akuuttiin haimatulehdukseen sairastuneiden potilaiden pitkäaikaisennustetta. Ensimmäisessä osatyössä ilmeni, että kaikille potilaille, joille suoritettiin haiman nekrosektomia kehittyi fisteli ja endoskooppinen transpapillaarinen haimateiden stenttaus (ETPS) osoittautui hyväksi ja turvalliseksi hoidoksi fistelin hoidossa. Toisessa prospektiivisessa randomoidussa kontrolloidussa osatyössä tutkittiin profylaktista haimateiden stenttausta nekrotisoivassa haimatulehduksessa. Tutkimus osoitti, etteivät potilaat hyötyneet stenttauksesta: toimenpiteestä oli enemmän haittaa kuin hyötyä. Tämän tutkimuksen mukaan protetisointia ei suositella tehtäväksi taudin alkuvaiheessa. Kolmannessa osatyössä selvitettiin haiman nekrosektomian jälkeisen haimafistelin diagnosointia. Tutkimustuloksen mukaan haimafistelin osoittamiseksi dreenieritteen amylaasitasoa mittaamalla tarvitaan useita mittauskertoja, koska yksittäisen mittauksen sensitiivisyys on matala. Neljännessä osatyössä analysoitiin Oulun yliopistollisessa sairaalassa 1995–2012 akuutin haimatulehduksen sairastaneiden työikäisten potilaiden pitkäaikaisennustetta ja kuolinsyitä. Noin kymmenen vuoden seurannassa tutkimusryhmän (n = 1 644) kuolleisuus oli yli nelinkertainen verrattuna ikä- ja sukupuolivakioituihin verrokeihin (n = 8 220). Merkittävin kuolleisuutta lisäävä tekijä oli alkoholi. Tutkimuksemme osoitti, että infektoituneen haimanekroosiin liittyvä haimafisteli on huomioitava hoidossa. Varhaisesta profylaktisesta haimateiden protetisoinnista ei tutkimuksessa osoitettu olevan hyötyä. Alkoholin aiheuttaman haimatulehduksen pitkäaikaisennusteen mortaliteetti on korkea johtuen alkoholin käytöstä ja siihen liittyvistä sairauksista.

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To study adaptation of pancreatic amylase to diet, an affinity adsorbent, alpha-GHI-AH-Sepharose 4B, was used to determine amylase synthesis in cultured pancreatic acinar cells. This adsorbent exhibited a consistent binding capacity and was specific for amylase. Acinar cells from rats fed high fat (HF) or carbohydrate (HC) diets for 7 d were cultured 1-48 h in serum-free medium. Amylase activity remained significantly higher in HC cells than in HF cells through 24 h in culture, despite its decrease with time in culture. The relative synthesis of amylase (3H-phe amylase/3H-phe total protein x 100) was significantly higher in HC than in HF cells at isolation and remained higher during culture. These results demonstrate that this affinity adsorbent can be used to determine amylase synthesis and suggest that the effect of diet on amylase activity and relative synthesis persists in cultured pancreatic acinar cells.

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Pancreatic ductal adenocarcinoma (PDAC) has a dismal prognosis. The aggressiveness and therapeutic recalcitrance of this malignancy has been attributed to multiple factors including the influence of an active desmoplastic stroma. How the stromal microenvironment of PDAC contributes to the fatal nature of this disease is not well defined. In the analysis of clinical specimens, we observed diverse expression of the hypoxic marker carbonic anhydrase IX and the lactate transporter MCT4 in the stromal compartment. These stromal features were associated with the epithelial to mesenchymal phenotype in PDAC tumor cells, and with shorter patient survival. Cultured cancer- associated fibroblasts (CAFs) derived from primary PDAC exhibited a high basal level of hypoxia inducible factor 1a (HIF1 alpha) that was both required and sufficient to modulate the expression of MCT4. This event was associated with increased transcription and protein synthesis of HIF1a in CAFs relative to PDAC cell lines, while surprisingly the protein turnover rate was equivalent. CAFs utilized glucose predominantly for glycolytic intermediates, whereas glutamine was the preferred metabolite for the TCA cycle. Unlike PDAC cell lines, CAFs were resistant to glucose withdrawal but sensitive to glutamine depletion. Consistent with the lack of reliance on glucose, CAFs could survive the acute depletion of MCT4. In co-culture and xenograft studies CAFs stimulated the invasive potential and metastatic spread of PDAC cell lines through a mechanism dependent on HIF1a and MCT4. Together, these data indicate that stromal metabolic features influence PDAC tumor cells to promote invasiveness and metastatic potential and associate with poor outcome in patients with PDAC.

Mutations in HNF1A cause Maturity Onset Diabetes of the Young type 3, the second most frequent form of diabetes caused by single gene mutation. We generated human stem cell-derived pancreatic endocrine cells with clinically pathogenic mutations in HNF1A and show that HNF1A deficiency impairs endocrine cell fate, insulin granule maturation and the secretion of insulin in response to glucose. Single-cell RNA sequencing reveals that HNF1A orchestrates a network of genes involved in β-cell fate, granule maturation, glucose metabolism, calcium ion binding and hormone exocytosis. In both patients and stem cell-derived β-cells, HNF1A deficiency altered the stoichiometry of secreted insulin to c-peptide. Sulfonylurea, used in the treatment of these patients, restored both insulin secretion and stoichiometry. The uncoupling of insulin and c-peptide secretion as described here questions the common practice of using c-peptide as a proxy to evaluate β-cell function. We also demonstrate that correction of the HNF1A mutations restores function, providing a path to cell-based replacement therapy.

Pancreatic Ductal Adenocarcinoma (PDAC) is one of the five leading causes of cancer-related deaths in the West, and this, largely, is due to metastatic disease. In order to better understand PDAC metastatic spread and identify novel therapeutic targets, we analysed the proteome of primary tumours and matched lymph node (LN) metastases. As frozen specimens of metastatic lesions are scarce, we examined formalin-fixed paraffin-embedded (FFPE) tissues. Whilst such tissue is in routine diagnostic use, the cross-linkages induced by fixation have, in the past, precluded proteomic investigation for research purposes. Recent technological advances have, however, overcome this technical limitation. Using laser capture microdissection (P.A.L.M system), we isolated malignant epithelia from seven FFPE primary PDAC tumours and matched LN metastases. Following dissection, samples were analysed in duplicate using Multidimensional Protein Identification Technology (MudPIT); this resulted in the identification of 1504 proteins, 854 of which were common to all samples analysed. Comparison of the obtained proteins with data from previous proteomics studies on pancreatic tissue, pancreatic juice, serum and urine resulted in a less than 30 % overlap, indicating that our study has expanded the current database of proteins expressed in this malignancy substantially. Statistical analysis further showed that 115/854 proteins (13.5%) were significantly differentially expressed (g-value ≥ 3.8). Two proteins, S100P and 14-3-3 sigma, with highly significant g-values were confirmed to be significantly differentially expressed (S100P: p = 0.05 and 14-3-3 sigma: p < 0.001) 4 in a larger series of 55 cases of matched primary PDAC and LN metastases using immunohistochemistry. We chose to investigate further the roles of S100P in lymphatic invasion in vitro and in vivo. By co-culturing a Panc1 S100P-overexpressing clone (S5L), or a vector control clone (V3L), with human dermal lymphatic endothelial cells (HDLEC), we were able to show that different receptors mediate S5L adhesion to resting and activated HDLEC as opposed to V3L; and that the presence of S5L cells in these co-cultures significantly increased permeability at one (p = 0.02), four (p = 0.002) and eight (p = 0.007) hours post-seeding, and significantly increased translymphatic endothelial migration at 72 hours (p = 0.006). Using the V3L and S5L cell lines, which were transduced to express luciferase, we also created an orthotopic mouse model of PDAC, as well as experimental metastatic mouse models, in CD1 nude mice. These models were used to evaluate the effects of S100P on primary tumour growth, metastasis and site-specific growth. S100P was only found to significantly increase primary tumour growth in this model (n = 10 animals/group), both by bioluminescence (p = 0.002) and tumour weight (p = 0.01). No metastases (spontaneous and/or experimental) were seen however. Thus, this model can be used to evaluate the anti-tumour efficacy of novel therapies to S100P in the future.