Metformin-mediated growth inhibition involves suppression of the IGF-I receptor signalling pathway in human pancreatic cancer cells

Background

Epidemiological studies have shown direct associations between type 2 diabetes and obesity, both conditions associated with hyperglycaemia and hyperinsulinemia, and the risk of pancreatic cancer. Up to 80% of pancreatic cancer patients present with either new-onset type 2 diabetes or impaired glucose tolerance at the time of diagnosis. Recent population studies indicate that the incidence of pancreatic cancer is reduced among diabetics taking metformin. In this study, the effects of exposure of pancreatic cancer cells to high glucose levels on their growth and response to metformin were investigated.

Methods

The human pancreatic cancer cell lines AsPC-1, BxPC-3, PANC-1 and MIAPaCa-2 were grown in normal (5 mM) or high (25 mM) glucose conditions, with or without metformin. The influence by metformin on proliferation, apoptosis and the AMPK and IGF-IR signalling pathways were evaluated in vitro.

Results

Metformin significantly reduced the proliferation of pancreatic cancer cells under normal glucose conditions. Hyperglycaemia however, protected against the metformin-induced growth inhibition. The anti-proliferative actions of metformin were associated with an activation of AMP-activated protein kinase AMPK^Thr172 together with an inhibition of the insulin/insulin-like growth factor-I (IGF-I) receptor activation and downstream signalling mediators IRS-1 and phosphorylated Akt. Furthermore, exposure to metformin during normal glucose conditions led to increased apoptosis as measured by poly(ADP-ribose) polymerase (PARP) cleavage. In contrast, exposure to high glucose levels promoted a more robust IGF-I response and Akt activation which correlated to stimulated AMPK^Ser485 phosphorylation and impaired AMPK^Thr172 phosphorylation, resulting in reduced anti-proliferative and apoptotic effects by metformin.

Conclusion

Our results indicate that metformin has direct anti-tumour activities in pancreatic cancer cells involving AMPK^Thr172 activation and suppression of the insulin/IGF signalling pathways. However, hyperglycaemic conditions enhance the insulin/IGF-I responses resulting in an altered AMPK activation profile and prevent metformin from fully switching off the growth promoting signals in pancreatic cancer cells.

Impact by pancreatic stellate cells on epithelial-mesenchymal transition and pancreatic cancer cell invasion: Adding a third dimension in vitro

Pancreatic cancer is associated with a highly abundant stroma and low-grade inflammation. In the local tumour microenvironment, elevated glucose levels, the presence of tumour-associated stellate cells and macrophages are hypothesised to promote the tumour progression and invasion. The present study investigated the influence by the microenvironment on pancreatic cancer cell invasion in vitro. After co-culture with tumour-associated pancreatic stellate cells (TPSCs), pancreatic cancer cells displayed up to 8-fold reduction in levels of epithelial-mesenchymal transition (EMT) markers E-cadherin and ZO-1, while β-catenin and vimentin levels were increased. A 3D organotypic model showed that TPSCs stimulated pancreatic cancer cell invasion, both as single cell (PANC-1) and cohort (MIAPaCa-2) invasion. The combined presence of TPSCs and M2-like macrophages induced invasion of the non-invasive BxPC-3 cells. High glucose conditions further enhanced changes in EMT markers as well as the cancer cell invasion. In summary, co-culture with TPSCs induced molecular changes associated with EMT in pancreatic cancer cells, regardless of differentiation status, and the organotypic model demonstrated the influence of microenvironmental factors, such as glucose, stellate cells and macrophages, on pancreatic cancer cell invasion.

The clinical importance of tumour-infiltrating macrophages and dendritic cells in periampullary adenocarcinoma differs by morphological subtype

Background

Dendritic cells (DC) and tumour-associated macrophages (TAM) are essential in linking the innate and adaptive immune response against tumour cells and tumour progression. These cells are also potential target for immunotherapy as well as providing a handle to investigate immune status in the tumour microenvironment. The aim of the present study was to examine their impact on prognosis and chemotherapy response in periampullary adenocarcinoma, including pancreatic cancer, with particular reference to morphological subtype.

Methods

The density of tolerogenic immature CD1a⁺ dendritic cells (DC), and MARCO⁺, CD68⁺ and CD163⁺ tissue-associated macrophages (TAM) was analysed by immunohistochemistry in tissue micro arrays with tumours from 175 consecutive cases of periampullary adenocarcinoma who had undergone pancreaticoduodenectomy, 110 with pancreatobiliary type (PB-type) and 65 with intestinal type (I-type) morphology. Kaplan–Meier and Cox regression analyses were applied to determine the impact of immune cell infiltration on 5-year overall survival (OS).

Results

High density of CD1a⁺ DCs was an independent prognostic factor for a reduced OS in PB-type but not in I-type tumours (adjusted HR = 2.35; 95% CI 1.13–4.87). High density of CD68⁺ and CD163⁺ TAM was significantly associated with poor OS in the whole cohort, however only in unadjusted analysis (HR = 1.67; 95% CI 1.06–2.63, and HR = 1.84; 95% CI 1.09–3.09, respectively) and not in strata according to morphological subtype. High density of MARCO⁺ macrophages was significantly associated with poor prognosis in I-type but not in PB-type tumours (HR = 2.14 95% CI 1.03–4.44), and this association was only evident in patients treated with adjuvant chemotherapy. The prognostic value of the other investigated immune cells did not differ significantly in strata according to adjuvant chemotherapy.

Conclusions

The results from this study demonstrate that high infiltration of tolerogenic immature DCs independently predicts a shorter survival in patients with PB-type periampullary adenocarcinoma, and that high density of the MARCO⁺ subtype of TAMs predicts a shorter survival in patients with I-type tumours. These results emphasise the importance of taking morphological subtype into account in biomarker studies related to periampullary cancer, and indicate that therapies targeting dendritic cells may be of value in the treatment of PB-type tumours, which are associated with the worst prognosis.

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-017-1256-y) contains supplementary material, which is available to authorized users.

Significant association and synergistic adverse prognostic effect of podocalyxin-like protein and epidermal growth factor receptor expression in colorectal cancer

BACKGROUND

Podocalyxin-like 1 (PODXL) is an anti-adhesive transmembrane protein that has been demonstrated to be an independent factor of poor prognosis in colorectal cancer (CRC). The gene encoding PODXL is located to chromosome 7, which also harbours the gene for the epidermal growth factor receptor (EGFR). The aim of this study was to examine the associations between PODXL and EGFR expression in CRC in vitro and in vivo.

METHODS

EGFR expression was analysed in tumours from three independent patient cohorts; cohort 1 (n = 533), cohort 2 (n = 259) and cohort 3 (n = 310), previously analysed for immunohistochemical PODXL expression and KRAS and BRAF mutations (cohort 1 and 3). Levels of EGFR and PODXL were determined by western blot in six different CRC cell lines.

RESULTS

High expression of PODXL was significantly associated with high EGFR expression (p < 0.001) in all three cohorts, and with BRAF mutation (p < 0.001) in cohort 1 and 3. High EGFR expression correlated with BRAF mutation (p < 0.001) in cohort 1. High EGFR expression was associated with adverse clinicopathological factors and independently predicted a reduced 5-year overall survival (OS) in cohort 1 (HR 1.77; 95 % CI 1.27-2.46), cohort 2 (HR 1.58; 95 % CI 1.05-2.38) and cohort 3 (HR 1.83; 95 % CI 1.19-2.81). The highest risk of death within 5 years was observed in patients with tumours displaying high expression of both EGFR and PODXL in cohort 1 and 3 (HR 1.97; 95 % CI 1.18-3.28 and HR 3.56; 95 % CI 1.75-7.22, respectively). Western blot analysis showed a uniform expression of PODXL and EGFR in all six examined CRC cell lines.

CONCLUSIONS

The results from this study demonstrate that high expression of EGFR is an independent factor of poor prognosis in CRC. Moreover, strong links have been uncovered between expression of the recently proposed biomarker candidate PODXL with EGFR expression in CRC in vivo and in vitro, and with BRAF mutation in vivo. High expression of both PODXL and EGFR may also have a synergistic adverse effect on survival. These findings suggest a potential functional link in CRC between PODXL, EGFR and BRAF, all originating from chromosome 7, which may be highly relevant in the clinical setting and therefore merit future in-depth study.

Translational study reveals a two-faced role of RBM3 in pancreatic cancer and suggests its potential value as a biomarker for improved patient stratification

Periampullary adenocarcinoma, including pancreatic cancer, is a heterogeneous group of tumors with dismal prognosis, partially due to lack of reliable targetable and predictive biomarkers. RNA-binding motif protein 3 (RBM3) has previously been shown to be an independent prognostic and predictive biomarker in several types of cancer. Herein, we examined the prognostic value of RBM3 in periampullary adenocarcinoma, as well as the effects following RBM3 suppression in pancreatic cancer cells in vitro. RBM3 mRNA levels were examined in 176 pancreatic cancer patients from The Cancer Genome Atlas. Immunohistochemical expression of RBM3 was analyzed in tissue microarrays with primary tumors and paired lymph node metastases from 175 consecutive patients with resected periampullary adenocarcinoma. Pancreatic cancer cells were transfected with anti-RBM3 siRNA in vitro and the influence on cell viability following chemotherapy, transwell migration and invasion was assessed. The results demonstrated that high mRNA-levels of RBM3 were significantly associated with a reduced overall survival (p = 0.026). RBM3 protein expression was significantly higher in lymph node metastases than in primary tumors (p = 0.005). High RBM3 protein expression was an independent predictive factor for the effect of adjuvant chemotherapy and an independent negative prognostic factor in untreated patients (p for interaction = 0.003). After siRNA suppression of RBM3 in vitro, pancreatic cancer cells displayed reduced migration and invasion compared to control, as well as a significantly increased resistance to chemotherapy. In conclusion, the strong indication of a positive response predictive effect of RBM3 expression in pancreatic cancer may be highly relevant in the clinical setting and merits further validation.

Expression and prognostic significance of human epidermal growth factor receptors 1, 2 and 3 in oesophageal and gastric adenocarcinomas preneoadjuvant and postneoadjuvant treatment

AIMS

Neoadjuvant treatment has now become the standard of care for oesophageal and gastric cancer. The aim of this study was to investigate the influence of neoadjuvant therapy on the expression of human epidermal growth factor receptor 1 (HER1/EGFR), HER2 and HER3, in oesophageal and gastric adenocarcinoma.

METHODS

Immunohistochemical expression of EGFR, HER2 and HER3 was examined and compared in pretreatment biopsies, post-treatment surgical resection specimens and metastases in a retrospective cohort of 166 patients with adenocarcinoma of the oesophagus or stomach. The relationship between expression of the investigative markers and histopathological response to neoadjuvant treatment, overall survival (OS) and recurrence free survival (RFS) was analysed.

RESULTS

Conversion of protein expression between pretreatment biopsy and post-treatment surgical resection was seen in 4.6% of the cases for EGFR, 5.9% for HER2% and 19.4% for HER3. Histopathological response to neoadjuvant treatment was significantly and stepwise associated with OS and RFS . High HER3 protein expression in post-treatment surgical resection specimens was significantly associated with a prolonged OS in univariable analysis (HR=0.39; 95% CI 0.17 to 0.93), but did not remain significant in multivariable analysis. Expression of EGFR and HER2 in post-treatment surgical resection specimens was not prognostic. No correlation between pretreatment HER-protein expression and histopathological response was seen.

CONCLUSIONS

The results from this study underscore the need for further studies on the influence of neoadjuvant treatment on biomarker expression, as this may influence treatment strategy as well as prognosis. Histopathological response is validated as a useful prognostic factor.

PRR11 unveiled as a top candidate biomarker within the RBM3-regulated transcriptome in pancreatic cancer

The outlook for patients with pancreatic cancer remains dismal. Treatment options are limited and chemotherapy remains standard of care, leading to only modest survival benefits. Hence, there is a great need to further explore the mechanistic basis for the intrinsic therapeutic resistance of this disease, and to identify novel predictive biomarkers. RNA‐binding motif protein 3 (RBM3) has emerged as a promising biomarker of disease severity and chemotherapy response in several types of cancer, including pancreatic cancer. The aim of this study was to unearth RBM3‐regulated genes and proteins in pancreatic cancer cells in vitro, and to examine their expression and prognostic significance in human tumours. Next‐generation RNA sequencing was applied to compare transcriptomes of MIAPaCa‐2 cells with and without RBM3 knockdown. The prognostic value of differentially expressed genes (DEGs) was examined in The Cancer Genome Atlas (TCGA). Top deregulated genes were selected for further studies in vitro and for immunohistochemical analysis of corresponding protein expression in tumours from a clinically well‐annotated consecutive cohort of 46 patients with resected pancreatic cancer. In total, 19 DEGs (p < 0.01) were revealed, among which some with functions in cell cycle and cell division stood out; PDS5A (PDS cohesin associated factor A) as the top downregulated gene, CCND3 (cyclin D3) as the top upregulated gene, and PRR11 (proline rich 11) as being highly prognostic in TCGA. Silencing of RBM3 in MiaPaCa‐2 cells led to congruent alterations of PDS5A, cyclin D3, and PRR11 levels. High protein expression of PRR11 was associated with adverse clinicopathological features and shorter overall survival. Neither PDS5A nor cyclin D3 protein expression was prognostic. This study unveils several RBM3‐regulated genes with potential clinical relevance in pancreatic cancer, among which PRR11 shows the most consistent association with disease severity, at both transcriptome and protein levels.

Intratumoural leukocyte infiltration is a prognostic indicator among pancreatic cancer patients with type 2 diabetes

BACKGROUND

The life expectancy of pancreatic cancer patients remains minimal. The disease progression may be influenced by type 2 diabetes (T2D) and inflammatory status, although important gaps persist around their joint effects on disease outcome. The aim of this study was to investigate the clinical significance of the tumour immune microenvironment on pancreatic cancer prognosis in relation to T2D status.

METHOD

Tumour-infiltrating macrophages, neutrophils and eosinophils were studied in primary pancreatic tumours and paired lymph node metastases in relation to patient and tumour characteristics, T2D status and overall survival in a retrospective cohort of patients with resectable pancreatic cancer in Sweden.

RESULTS

Of the 80 included pancreatic cancer patients, 22 (27.2%) had T2D. The diabetic pancreatic cancer patients had significantly higher systemic high white blood cell count than those without diabetes (P = 0.028). Macrophage infiltration levels were higher in lymph node metastases compared with primary tumours (P = 0.040) among pancreatic cancer patients with diabetes. Type 2 diabetes or intra-tumoural leukocyte (macrophage, neutrophil or eosinophil) infiltration alone did not significantly influence pancreatic cancer prognosis. However, among cancer patients with T2D high macrophage or neutrophil tumour-infiltration was associated with a significant reduction in overall survival (adjusted hazard ratio [HR] 7.2; 95% CI 1.5-35.0 and HR 5.4; 95% CI 1.1-26.3, respectively).

CONCLUSION

These results demonstrate associations between T2D and enhanced inflammatory processes with significant implications on survival among pancreatic cancer patients with T2D. Validation in larger independent patient cohorts may identify additional prognostic tools and improved treatment strategies for specific patient subsets.

Mutational Landscape in Resected Periampullary Adenocarcinoma: Relationship With Morphology and Clinical Outcome

PURPOSE

Periampullary adenocarcinomas encompass a heterogeneous group of tumors with dismal prognosis and limited treatment options. Emerging evidence shows that tumor morphology (ie, intestinal type [I-type] or pancreatobiliary type [PB-type]) is a more relevant prognostic factor than tumor origin. Knowledge is sparse, however, on whether key mutations differ according to morphology.

MATERIALS AND METHODS

Next-generation sequencing was applied to assess the mutational status of 70 genes in 102 tumors from a retrospective cohort of 175 patients with resected periampullary adenocarcinoma. Brahma-related gene 1 protein expression was examined by immunohistochemistry on tissue microarrays with primary tumors from the original cohort.

RESULTS

APC mutations were significantly more common in I-type than in PB-type tumors (27.5% v 0%; P < .001), as were ERBB3 mutations (20.8% v 4.8%; P = .016), whereas CDKN2A mutations were more common in PB-type than in I-type tumors (19.4% v 2.5%; P = .013). KRAS mutation was an independent factor of poor prognosis in I-type tumors (hazard ratio, 3.73; 95% CI, 1.10 to 12.67). In PB-type tumors, SMARCA4 mutation was an adverse prognostic factor in patients not receiving adjuvant chemotherapy, and there was a significant treatment interaction between expression of Brahma-related gene 1 protein, the protein encoded by SMARCA4, and adjuvant chemotherapy (P_interaction = .007).

CONCLUSION

To our knowledge, this is the first description of the mutational landscape in the full spectrum of periampullary adenocarcinoma that demonstrates that the distribution and prognostic and predictive significance of commonly mutated genes differ by morphology. The results emphasize that morphology is an important factor to consider in the search for novel biomarkers and targeted personalized treatment of these patients. In addition, the findings support the concept that molecular profiling of these tumors could be of clinical benefit.

Chemotherapy, host response and molecular dynamics in periampullary cancer: the CHAMP study

BACKGROUND

Pancreatic cancer is a devastating disease with a dismal prognosis. Despite profound medical advances in systemic therapies for other types of aggressive tumours during recent years, a diagnosis of pancreatic cancer is still often synonymous with a fatal outcome. The term periampullary cancer includes pancreatic cancer and applies to the group of tumours found in proximity to the ampulla of Vater. Molecular events and immune response in the host during chemotherapy remain largely unexplored in this group of tumours. Therefore, the "Chemotherapy, Host Response and Molecular Dynamics in Periampullary Cancer (CHAMP)" study aims to monitor these processes to gain new insight into this perplexing disease.

METHODS

The CHAMP study is a prospective, single-arm observational study. All patients diagnosed with pancreatic or other periampullary adenocarcinoma undergoing adjuvant or palliative chemotherapy treatment in the Department of Oncology, Skåne University Hospital, are invited to participate. Clinical and pathological data will be compiled at study entry. A single tissue microarray (TMA) block is constructed for each patient with a resected tumour and blood samples are drawn before, during and after chemotherapy in order to sample peripheral blood mononuclear cells (PBMC), cytokines and circulating tumour DNA (ctDNA). Next generation sequencing will be performed on tumour tissue and ctDNA to detect changes in the clonal landscape over space and time.

DISCUSSION

Despite the recent emergence of some promising biomarkers for periampullary cancer, there has been a lack of success in clinical implementation. Cancer cells continuously adapt and become resistant to treatment during chemotherapy. To be able to keep pace with and hopefully overtake this rapid evolution we must, with the help of new diagnostic tools, be ready to adapt and alter treatment accordingly. It seems to us that the only way forward is to gain a better understanding of the dynamics of the disease during treatment. With insights gained from the CHAMP study we hope to find answers to key questions in this largely unexplored territory.

TRIAL REGISTRATION

This study has been registered 30th October 2018 at clinicaltrials.gov as NCT03724994.

Additive clinical impact of epidermal growth factor receptor and podocalyxin-like protein expression in pancreatic and periampullary adenocarcinomas

The outcome of periampullary adenocarcinomas remains poor with few treatment options. Podocalyxin-like protein (PODXL) is an anti-adhesive protein, the high expression of which has been shown to confer a poor prognosis in numerous malignancies. A correlation and adverse prognostic synergy between PODXL and the epidermal growth factor receptor (EGFR) has been observed in colorectal cancer. Here, we investigated whether this also applies to periampullary adenocarcinomas. We analyzed the immunohistochemical expression of PODXL and EGFR in tissue microarrays with tumors from two patient cohorts; (Cohort 1, n = 175) and (Cohort 2, n = 189). The effect of TGF-β-induced expression and siRNA-mediated knockdown of PODXL and EGFR, were investigated in pancreatic cancer cells (PANC-1) in vitro. We found a correlation between PODXL and EGFR in these cancers, and a synergistic adverse effect on survival. Furthermore, silencing PODXL in pancreatic cancer cells resulted in the down-regulation of EGFR, but not vice versa. Consequently, these findings suggest a functional link between PODXL and EGFR, and the potential combined utility as biomarkers possibly improving patient stratification. Further studies examining the mechanistic basis underlying these observations may open new avenues of targeted treatment options for subsets of patients affected by these particularly aggressive cancers.

Abstract 5156: Hyperglycemia enhances IGF-I responses and alters the AMPK activation profile that protects against metformin-induced growth inhibition in pancreatic cancer cells

Epidemiological studies have shown direct associations between type 2 diabetes (T2D) and obesity, both conditions associated with hyperglycemia and hyperinsulinemia, and the risk of pancreatic cancer. Up to 80% of pancreatic cancer patients are diagnosed with either impaired glucose tolerance or new-onset T2D one or two years prior to their cancer diagnosis. Recent population studies indicate that the incidence of pancreatic cancer is reduced among diabetics taking metformin, an insulin-sensitizing and glucose lowering drug. We investigated the effects of exposure of pancreatic cancer cells to high glucose levels on their growth and response to metformin. We found that metformin significantly reduced the proliferation of pancreatic cancer cells under normal glucose conditions, but that hyperglycemia protected against the metformin-induced growth inhibition. The antiproliferative actions of metformin were associated with an activation of AMP-activated protein kinase AMPK(T172) together with a dose-dependent suppression of the insulin/insulin-like growth factor (IGF) signaling mediators IRS-1 and phosphorylated AKT. Furthermore, exposure to metformin during normal glucose led to increased apoptosis as measured by poly(ADP-ribose) polymerase (PARP) cleavage. In contrast, exposure to high glucose promoted a more robust IGF-I response and AKT activation, that stimulated AMPK(S485) phosphorylation and suppressed AMPK(T172) phosphorylation resulting in reduced antiproliferative and apoptotic effects by metformin. In conclusion, our results indicate that metformin has direct antitumor activities in pancreatic cancer cells involving AMPK(T172) activation and modulation of the insulin/IGF signaling pathways. However, hyperglycemic conditions enhance the insulin/IGF-I responses resulting in an altered AMPK activation profile that prevent metformin from fully switching of the growth promoting signals in pancreatic cancer cells.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 5156. doi:1538-7445.AM2012-5156

Expression of PD-L1 in periampullary adenocarcinoma: Relationship with morphological type, the immune microenvironment and prognosis

268

Background: Overall survival for patients with periampullary adenocarcinoma, including pancreatic cancer, continues to be poor. Pancreatic cancer is characterized by a largely immunosuppressive microenvironment, but blockade of the programmed death ligand 1 (PD-L1) pathway has still not been effective. Reports on the prognostic value of PD-L1 expression in pancreatic and in particular periampullary cancer are sparse. The aim of this study was therefore to analyze PD-L1 expression in periampullary adenocarcinoma, with specific reference to morphological type, tumor-infiltrating immune cells, and survival. Methods: PD-L1 expression in tumor cells (TC) and immune cells (IC) was assessed by immunohistochemistry on tissue microarrays with primary tumors from a retrospective consecutive cohort of 175 patients with resected periampullary adenocarcinoma, 65 of intestinal(I)-type and 110 of pancreatobiliary(PB)-type. Correlations with various immune cells were calculated with non-parametric tests. Cox proportional hazards models were applied to calculate hazard ratios (HR) and 95% confidence intervals (CI) for death. Results: TC PD-L1 expression was not associated with any clinicopathological factors nor with survival. IC PD-L1 ( > 10%) expression was higher in I-type than in PB-type tumors (p < 0.001), and correlated with defect mismatch repair (p = 0.012) and lymph node negativity (p = 0.016). IC PD-L1 was not prognostic in PB-type tumors. High IC PD-L1 was associated with a prolonged survival in the entire cohort (HR = 0.59, CI 0.40-0.88), and in I-type tumors (HR = 0.38, CI 0.18-0.81), but not after adjustment for other prognostic factors. In I-type tumors, high IC PD-L1 correlated with high density of T cells (CD3+, CD8+, FoxP3+), but not with B cell or macrophage density. There were no significant associations between IC PD-L1 expression and any other immune cells in PB-type tumors. Conclusions: High PD-L1 expression in IC is associated with a T cell dense tumor microenvironment and a prolonged survival in I-type, but not in PB-type, periampullary adenocarcinoma, thus indicating that the effect of immune-modulating therapies may differ by morphological type.

A translational effort to identify prognostic and predictive biomarkers in pancreatic cancer among RBM3-regulated genes

305

Background: Pancreatic cancer has a dismal prognosis and clinical protocols are still lacking predictive biomarkers. RNA-binding motif protein 3 (RBM3) has emerged as a promising biomarker in several solid cancers, including pancreatic cancer. High RBM3 expression in human tumors has been associated with good response to chemotherapy, as well as to confer increased chemosensitivity in vitro. The aim of this study was to identify RBM3-regulated genes in pancreatic cells in vitro, and further interrogate their potential utility as prognostic and predictive biomarkers in a translational setting. Methods: Next generation RNA-sequencing was applied to compare gene expression between MIAPaCa-2 cells with siRNA-downregulated RBM3 and control cells. Single genes with the strongest association to RBM3 were further selected by gene set enrichment analysis, and their prognostic value in pancreatic cancer was examined in The Cancer Genome Atlas (TCGA). The most promising biomarker candidates with well-validated antibodies were then analyzed by immunohistochemistry in tissue microarrays with tumors from a consecutive, retrospective cohort of 175 patients with periampullary and pancreatic adenocarcinoma. Results: MIAPaCa-2 cells with downregulated RBM3 displayed 21 differentially expressed genes (p < 0.01). One of the top downregulated genes was PDS cohesion associated factor A (PDS5A) encoding a protein involved in sister chromatid cohesion. PDS5A protein expression was reduced in siRBM3-treated MIAPaCa-2 cells compared to control cells. High PDS5A mRNA expression was significantly associated with a reduced survival in pancreatic cancer in the TCGA (n = 176, p = 0.026). High PDS5A protein expression in the separate cohort was significantly associated with a poor prognosis but predictive of improved response to adjuvant chemotherapy in KRAS-mutated, but not wild-type, pancreatobiliary-type tumors (p for interaction = 0.043). Conclusions: Here, we provide the first report of the expression of PDS5A in pancreatic and periampullary cancer, suggesting its potential utility as a prognostic and predictive biomarker. Further studies to unravel the underlying mechanisms are encouraged.

Clinical impact of tumour-infiltrating B-cells in periampullary adenocarcinoma in relation to adjuvant chemotherapy

330

Background: The prognostic significance of tumour-infiltrating lymphocytes of the B lineage in solid cancers has only recently begun to receive attention. Herein, we explored the relationship between B cell and plasma cell density and survival in patients with periampullary adenocarcinoma, including pancreatic cancer, with particular reference to morphological type. Methods: Immunohistochemistry was applied to quantify the abundance of B cells (CD20+), and plasma cells (CD138+) in tissue microarrays with tumours from a retrospective consecutive cohort of 175 patients who had undergone pancreaticoduodenectomy for periampullary adenocarcinoma. Cox regression was applied to calculate univariable and multivariable hazard ratios (HR) for recurrence and death within five years up until March 2017. Multivariable HRs were adjusted for established clinical parameters. Results: High CD20+ cell density was an independent prognostic factor for a prolonged overall survival in both intestinal-type (HR 0.32; 95% CI 0.12-0.86) and pancreatobiliary-type (HR 0.38; 95% CI 0.23-0.66) tumours. CD138+ was an independent prognostic factor in pancreatobiliary-type tumours (HR 0.51; 95% CI 0.32-0.82) only. A significant positive interaction was seen between adjuvant chemotherapy and CD20+ cells in relation to OS for PB-type tumours (pinteraction= 0.027). Conclusions: These results demonstrate that dense infiltration into the tumour by cells of the B lymphocyte lineage confers an improved prognosis in periampullary adenocarcinoma including pancreatic cancer. The impact of B cells in the local anti-tumour response is gradually being unravelled, and their potential influence on adjuvant chemotherapy response in the more aggressive pancreatobiliary-type tumours may be clinically relevant and merits further study.

Abstract B17: Tumor-associated stellate cells promote an invasive phenotype of pancreatic cancer cells

At the time of diagnosis, almost 80% of pancreatic cancer patients present with either new-onset type 2 diabetes or impaired glucose tolerance. Pancreatic cancer is associated with a highly abundant stroma, which is believed to influence the pathogenesis of the disease. In the local tumor microenvironment, both elevated glucose levels and the presence of tumor-associated stellate cells are hypothesized to promote the tumor progression and invasion by tumor cells. In this study, the influence by the microenvironment on pancreatic cancer cell invasion was investigated in vitro. Epithelial-to-mesenchymal transition (EMT) of human pancreatic cancer cells co-cultured in normal (5mM) or high (25 mM) glucose conditions with tumor-associated pancreatic stellate cells (TPSCs) was monitored by Western immunoblotting. In addition, a three-dimensional organotypic model was established to study and visualize the pancreatic cancer cell invasion. After co-culture, the expression of several EMT-markers was altered. The levels of E-cadherin were reduced by more than 95% (P&lt;0.001) while vimentin was increased by 45% (P&lt;0.05). In addition, high glucose conditions reduced the levels of ZO-1 and β-catenin compared to normal glucose. TGF-β stimulation, a known inducer of EMT, resulted in a similar modulation of EMT markers. The organotypic model showed differences in the extent of invasion between the cell lines investigated, of which PANC-1 human pancreatic cells were shown to be the most invasive and also formed a highly proliferative epithelium. In high glucose conditions, the invasion of PANC-1 cells appeared to increase both in number and distance covered by the cells. Immunofluorescent staining of EMT-markers in organotypic sections displayed a lack of E-cadherin and extensive expression of vimentin in the tumor epithelium. In conclusion, this study show TPSCs to induce changes in pancreatic cancer cells associated with enhanced invasiveness. In addition, a three-dimensional model visualized the invasive potential of the pancreatic cancer cells, which was further enhanced by high glucose conditions. This study contributes to further elucidate the interplay between, and influence of, the cell types present in the local tumor microenvironment, which promotes the tumor cell invasion as an important step in the pancreatic tumor progression.

Citation Format: Emelie Karnevi, Ann H. Rosendahl, Moin A. Saleem, Roland Andersson. Tumor-associated stellate cells promote an invasive phenotype of pancreatic cancer cells. [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer: Innovations in Research and Treatment; May 18-21, 2014; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2015;75(13 Suppl):Abstract nr B17.

Prognostic significance of professional antigen presenting cells according to morphological subtype of periampullary adenocarcinoma

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Background: Dendritic cells (DCs) and macrophages play vital roles in tumorigenesis and may, depending on the context, promote or inhibit tumor progression. In this study, we examined the prognostic significance of DCs and macrophages in periampullary adenocarcinoma, with particular reference to morphological type. Methods: Immune cell-specific expression of CD68, CD163 and CD1a was analysed by immunohistochemistry on tissue microarrays with tumours from 175 consecutive cases of periampullary adenocarcinoma, 110 of pancreatobiliary type (PB-type) and 65 of intestinal type (I-type) morphology. Kaplan-Meier and Cox regression analysis were applied to determine the impact of the investigated cells on 5-year overall survival (OS). Results: Low density of CD68+ cells or CD163 + cells was significantly associated with an improved 5-year OS in unadjusted Cox regression analysis in the entire cohort (HR = 1.66; 95% CI 1.05-2.63 and HR = 1.84; 95 % CI 1.09-3.09, respectively), but not in adjusted analysis or in strata according to subtype. CD1a+ cell density was not prognostic in entire cohort or in I-type tumours. However, in PB-type tumors, high CD1a+ cell density was significantly associated with a reduced OS in unadjusted as well as in adjusted analysis (HR = 2.09; 95% CI 1.07-4.09 and HR = 2.35; 95% CI 1.13-4.87). The prognostic value of the investigated markers did not differ in strata according to adjuvant chemotherapy, neither in the entire cohort nor according to morphological type. Conclusions: The results from study demonstrate that the prognostic significance of dendritic cells, but not macrophages, differs by morphological subtype in periampullary adenocarcinoma. Hence, morphological subtype is an important factor to consider in studies on the prognostic and predictive role of the immune microenvironment in these types of cancer.