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

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-beta -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.Peer reviewe

The Pancreatic Tumour Microenvironment. Influence by macrophages and glucose levels on tumourigenesis.

Pancreatic cancer is the fourth cause of cancer-related death with a 5-year survival rate less than 5%. Two of the risk factors are chronic pancreatitis and type 2 diabetes (T2D), which are believed to promote the tumour progression. Pancreatic cancer and its tumour microenvironment is characterised by a dense stroma, immune cell infiltration and poor vascularisation. This creates a favourable environment for cancer cells to grow, proliferate and invade surrounding tissue. The cell types orchestrating the local environment have shown to be pancreatic stellate cells and tumour-associated macrophages (TAMs), which control the local inflammation, provide growth factors and stimulate extra-cellular matrix (ECM) remodelling. In addition, the hypoxic environment induces a skewed metabolism in cancer cells due to the poor vascularisation, which creates dependencies on nutrients such as glucose. In this thesis, the role of the tumour microenvironment in pancreatic cancer was investigated, in particular the influence by hyperglycaemia and the interplay between pancreatic cancer cells and TAMs. High glucose levels was shown to promote proliferation, survival and enhanced invasion by pancreatic cancer cells. Pancreatic stellate cells induced epithelial-mesenchymal transition in pancreatic cancer cells and stimulated invasion into the ECM. Macrophages further enhanced the pancreatic cancer cell invasion and were found to be an indicator for survival in pancreatic cancer patients with T2D. In turn, pancreatic cancer cells were shown to stimulate macrophage differentiation with pro-tumour properties. Furthermore, the anti-diabetic drug metformin displayed direct anti-tumour and anti-inflammatory properties by inducing pancreatic cancer cell apoptosis and suppressing macrophage differentiation. In summary, the interplay between pancreatic cancer cells and its local environment is complex and of importance for tumour progression. Novel treatment strategies will need to broaden the view on cancer to also include the surrounding factors and cell types, to more efficiently treat cancer and create a better outcome for patients with pancreatic cancer

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

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

Tumour-educated macrophages display a mixed polarisation and enhance pancreatic cancer cell invasion.

At the time of diagnosis, almost 80% of pancreatic cancer patients present with new-onset type 2 diabetes (T2D) or impaired glucose tolerance. T2D and pancreatic cancer are both associated with low-grade inflammation. Tumour-associated macrophages (TAMs) have a key role in cancer-related inflammation, immune escape, matrix remodelling and metastasis. In this study, the interplay between tumour cells and immune cells under the influence of different glucose levels was investigated. Human peripheral blood mononuclear cells were exposed in vitro to conditioned medium from BxPC-3 human pancreatic cancer cells, in normal (5 mM) or high (25 mM) glucose levels. Flow cytometry analyses demonstrated that tumour-derived factors stimulated differentiation of macrophages, with a mixed classical (M1-like) and alternatively activated (M2-like) phenotype polarisation (CD11c(+)CD206(+)). High-glucose conditions further enhanced the tumour-driven macrophage enrichment and associated interleukin (IL)-6 and IL-8 cytokine levels. In addition, hyperglycaemia enhanced the responsiveness of tumour-educated macrophages to lipopolysaccharide, with elevated cytokine secretion compared with normal glucose levels. Tumour-educated macrophages were found to promote pancreatic cancer cell invasion in vitro, which was significantly enhanced at high glucose. The anti-diabetic drug metformin shifted the macrophage phenotype polarisation and reduced the tumour cell invasion at normal, but not high, glucose levels. In conclusion, this study demonstrates that pancreatic cancer cells stimulate differentiation of macrophages with pro-tumour properties that are further enhanced by hyperglycaemia. These findings highlight important crosstalk between tumour cells and TAMs in the local tumour microenvironment that may contribute to disease progression in pancreatic cancer patients with hyperglycaemia and T2D.Immunology and Cell Biology advance online publication, 25 March 2014; doi:10.1038/icb.2014.22

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

Expression and Prognostic Significance of Human Epidermal Growth Factor Receptors 1 and 3 in Gastric and Esophageal Adenocarcinoma.

Gastric and esophageal adenocarcinomas are major global cancer burdens. These cancer forms are characterized by a poor prognosis and a modest response to chemo- radio- and targeted treatment. Hence there is an obvious need for further enhanced diagnostic and treatment strategies. The aim of this study was to examine the expression and prognostic impact of human epidermal growth factor receptor 1 (HER1/EGFR) and 3 (HER3), as well as the occurrence of EGFR and KRAS mutations in gastric and esophageal adenocarcinoma