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COX-2 overexpression in resected pancreatic head adenocarcinomas correlates with favourable prognosis.

Pomianowska E, Schjølberg AR, Clausen OP, Gladhaug IP - BMC Cancer (2014)

Bottom Line: In tumours of pancreatobiliary type of histopathological differentiation, COX-2 expression did not significantly affect overall patient survival.In PC, COX-2 expression was significantly associated with high degree of differentiation (p = 0.002).In pancreatic cancer, COX-2 overexpression is significantly associated with the degree of differentiation and independently predicts a favourable prognosis.

View Article: PubMed Central - HTML - PubMed

Affiliation: Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway. ewa.pomianowska@medisin.uio.no.

ABSTRACT

Background: Overexpression of cyclooxygenase-2 (COX-2) has been implicated in oncogenesis and progression of adenocarcinomas of the pancreatic head. The data on the prognostic importance of COX expression in these tumours is inconsistent and conflicting. We evaluated how COX-2 overexpression affected overall postoperative survival in pancreatic head adenocarcinomas.

Methods: The study included 230 consecutive pancreatoduodenectomies for pancreatic cancer (PC, n = 92), ampullary cancer (AC, n = 62) and distal bile duct cancer (DBC, n = 76). COX-2 expression was assessed by immunohistochemistry. Associations between COX-2 expression and histopathologic variables including degree of differentiation, histopathologic type of differentiation (pancreatobiliary vs. intestinal) and lymph node ratio (LNR) were evaluated. Unadjusted and adjusted survival analysis was performed.

Results: COX-2 staining was positive in 71% of PC, 77% in AC and 72% in DBC. Irrespective of tumour origin, overall patient survival was more favourable in patients with COX-2 positive tumours than COX-2 negative (p = 0.043 in PC, p = 0.011 in AC, p = 0.06 in DBC). In tumours of pancreatobiliary type of histopathological differentiation, COX-2 expression did not significantly affect overall patient survival. In AC with intestinal differentiation COX-2 expression significantly predicted favourable survival (p = 0.003). In PC, COX-2 expression was significantly associated with high degree of differentiation (p = 0.002). COX-2 and LNR independently predicted good prognosis in a multivariate model.

Conclusions: COX-2 is overexpressed in pancreatic cancer, ampullary cancer and distal bile duct cancer and confers a survival benefit in all three cancer types. In pancreatic cancer, COX-2 overexpression is significantly associated with the degree of differentiation and independently predicts a favourable prognosis.

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COX-2 expression in tumour tissue from pancreatic cancer. a-d Double immunostaing with monoclonal anti-COX-2 antibody (Thermo Fischer Scientific rabbit) and monoclonal anti-αSMA (Dako). COX-2 tumour positive cells (red colour), αSMA positive stromal cells (brown colour). a magnification × 100, b magnification × 200, c Heterogeneity in COX-2 expression within pancreatic cancer tissue. Areas with moderate to strong staining (thick arrow) coexist with COX-2 negative areas (thin arrow), (magnification x 100) d Moderately to strong COX-2 staining in islet cells (thin arrow), pancreatic cancer negative for COX-2 staining, (magnification x 100). e Immunohistochemistry of COX-2 expression in tumour tissue from pancreatic cancer. Immunostaining with monoclonal COX-2 mouse antibody Invitrogen (the same tumour as in a), magnification x 100. f Western blot of COX-2 expression in the moderately differentiated pancreatic cancer cell lines BxPC3 and HPAFII known to overexpress COX-2, with and without induction by interleukin 1 (Il-1), showed a specific bond for COX-2 (70 kDA) (monoclonal COX-2 mouse antibody Invitrogen).
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Figure 1: COX-2 expression in tumour tissue from pancreatic cancer. a-d Double immunostaing with monoclonal anti-COX-2 antibody (Thermo Fischer Scientific rabbit) and monoclonal anti-αSMA (Dako). COX-2 tumour positive cells (red colour), αSMA positive stromal cells (brown colour). a magnification × 100, b magnification × 200, c Heterogeneity in COX-2 expression within pancreatic cancer tissue. Areas with moderate to strong staining (thick arrow) coexist with COX-2 negative areas (thin arrow), (magnification x 100) d Moderately to strong COX-2 staining in islet cells (thin arrow), pancreatic cancer negative for COX-2 staining, (magnification x 100). e Immunohistochemistry of COX-2 expression in tumour tissue from pancreatic cancer. Immunostaining with monoclonal COX-2 mouse antibody Invitrogen (the same tumour as in a), magnification x 100. f Western blot of COX-2 expression in the moderately differentiated pancreatic cancer cell lines BxPC3 and HPAFII known to overexpress COX-2, with and without induction by interleukin 1 (Il-1), showed a specific bond for COX-2 (70 kDA) (monoclonal COX-2 mouse antibody Invitrogen).

Mentions: Immunohistochemistry was performed on whole tumour slices, which were assessed without prior knowledge of the clinical and pathological parameters. In each section, five different representative high-power fields (100×) with tumour infiltration were selected and examined by light microscopy. The intensity of staining was estimated on a scale from 1-3 (1-negative, 2-moderate, 3-strong). Cells were considered positive only if COX-2 intensity was moderate or strong. The extent of the immunolabeling was assessed as the percentage of positively stained tumour cells and was expressed on the scale from 1-3 where 1 represented less than 10% cells stained, 2 represented 10-50% and 3 over 50%. Since COX-2 demonstrated considerable heterogeneity within individual cases, the final immunoscore was obtained as the average of the numeric scores for five high-power fields of each case considered positive in intensity scoring. Based on histograms of the staining for all tumours, the optimal cut-off value for discrimination between negative and positive staining was found to be 1.4. Islets of Langerhans and mucosa of the duodenum were moderately to strongly positive for COX-2, including those tumours with no COX-2 expression, and served as internal controls. Identical sections with omission of the primary antibody were used as negative controls. To test the validity of the Thermo antibody used for the study cohort, we performed additional immunostaining with a different monoclonal COX-2 mouse antibody, Invitrogen (Camarillo, CA, USA), on duplicates of twenty pancreatic cancer slides from the study cohort. The results were identical (Figure 1a and e). As Thermo antibody was not suitable for western blotting (producer recommendation), only the Invitrogen antibody was subjected to analysis by western blotting. The results showed a highly specific bond for COX-2 (Figure 1f).


COX-2 overexpression in resected pancreatic head adenocarcinomas correlates with favourable prognosis.

Pomianowska E, Schjølberg AR, Clausen OP, Gladhaug IP - BMC Cancer (2014)

COX-2 expression in tumour tissue from pancreatic cancer. a-d Double immunostaing with monoclonal anti-COX-2 antibody (Thermo Fischer Scientific rabbit) and monoclonal anti-αSMA (Dako). COX-2 tumour positive cells (red colour), αSMA positive stromal cells (brown colour). a magnification × 100, b magnification × 200, c Heterogeneity in COX-2 expression within pancreatic cancer tissue. Areas with moderate to strong staining (thick arrow) coexist with COX-2 negative areas (thin arrow), (magnification x 100) d Moderately to strong COX-2 staining in islet cells (thin arrow), pancreatic cancer negative for COX-2 staining, (magnification x 100). e Immunohistochemistry of COX-2 expression in tumour tissue from pancreatic cancer. Immunostaining with monoclonal COX-2 mouse antibody Invitrogen (the same tumour as in a), magnification x 100. f Western blot of COX-2 expression in the moderately differentiated pancreatic cancer cell lines BxPC3 and HPAFII known to overexpress COX-2, with and without induction by interleukin 1 (Il-1), showed a specific bond for COX-2 (70 kDA) (monoclonal COX-2 mouse antibody Invitrogen).
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Related In: Results  -  Collection

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Figure 1: COX-2 expression in tumour tissue from pancreatic cancer. a-d Double immunostaing with monoclonal anti-COX-2 antibody (Thermo Fischer Scientific rabbit) and monoclonal anti-αSMA (Dako). COX-2 tumour positive cells (red colour), αSMA positive stromal cells (brown colour). a magnification × 100, b magnification × 200, c Heterogeneity in COX-2 expression within pancreatic cancer tissue. Areas with moderate to strong staining (thick arrow) coexist with COX-2 negative areas (thin arrow), (magnification x 100) d Moderately to strong COX-2 staining in islet cells (thin arrow), pancreatic cancer negative for COX-2 staining, (magnification x 100). e Immunohistochemistry of COX-2 expression in tumour tissue from pancreatic cancer. Immunostaining with monoclonal COX-2 mouse antibody Invitrogen (the same tumour as in a), magnification x 100. f Western blot of COX-2 expression in the moderately differentiated pancreatic cancer cell lines BxPC3 and HPAFII known to overexpress COX-2, with and without induction by interleukin 1 (Il-1), showed a specific bond for COX-2 (70 kDA) (monoclonal COX-2 mouse antibody Invitrogen).
Mentions: Immunohistochemistry was performed on whole tumour slices, which were assessed without prior knowledge of the clinical and pathological parameters. In each section, five different representative high-power fields (100×) with tumour infiltration were selected and examined by light microscopy. The intensity of staining was estimated on a scale from 1-3 (1-negative, 2-moderate, 3-strong). Cells were considered positive only if COX-2 intensity was moderate or strong. The extent of the immunolabeling was assessed as the percentage of positively stained tumour cells and was expressed on the scale from 1-3 where 1 represented less than 10% cells stained, 2 represented 10-50% and 3 over 50%. Since COX-2 demonstrated considerable heterogeneity within individual cases, the final immunoscore was obtained as the average of the numeric scores for five high-power fields of each case considered positive in intensity scoring. Based on histograms of the staining for all tumours, the optimal cut-off value for discrimination between negative and positive staining was found to be 1.4. Islets of Langerhans and mucosa of the duodenum were moderately to strongly positive for COX-2, including those tumours with no COX-2 expression, and served as internal controls. Identical sections with omission of the primary antibody were used as negative controls. To test the validity of the Thermo antibody used for the study cohort, we performed additional immunostaining with a different monoclonal COX-2 mouse antibody, Invitrogen (Camarillo, CA, USA), on duplicates of twenty pancreatic cancer slides from the study cohort. The results were identical (Figure 1a and e). As Thermo antibody was not suitable for western blotting (producer recommendation), only the Invitrogen antibody was subjected to analysis by western blotting. The results showed a highly specific bond for COX-2 (Figure 1f).

Bottom Line: In tumours of pancreatobiliary type of histopathological differentiation, COX-2 expression did not significantly affect overall patient survival.In PC, COX-2 expression was significantly associated with high degree of differentiation (p = 0.002).In pancreatic cancer, COX-2 overexpression is significantly associated with the degree of differentiation and independently predicts a favourable prognosis.

View Article: PubMed Central - HTML - PubMed

Affiliation: Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway. ewa.pomianowska@medisin.uio.no.

ABSTRACT

Background: Overexpression of cyclooxygenase-2 (COX-2) has been implicated in oncogenesis and progression of adenocarcinomas of the pancreatic head. The data on the prognostic importance of COX expression in these tumours is inconsistent and conflicting. We evaluated how COX-2 overexpression affected overall postoperative survival in pancreatic head adenocarcinomas.

Methods: The study included 230 consecutive pancreatoduodenectomies for pancreatic cancer (PC, n = 92), ampullary cancer (AC, n = 62) and distal bile duct cancer (DBC, n = 76). COX-2 expression was assessed by immunohistochemistry. Associations between COX-2 expression and histopathologic variables including degree of differentiation, histopathologic type of differentiation (pancreatobiliary vs. intestinal) and lymph node ratio (LNR) were evaluated. Unadjusted and adjusted survival analysis was performed.

Results: COX-2 staining was positive in 71% of PC, 77% in AC and 72% in DBC. Irrespective of tumour origin, overall patient survival was more favourable in patients with COX-2 positive tumours than COX-2 negative (p = 0.043 in PC, p = 0.011 in AC, p = 0.06 in DBC). In tumours of pancreatobiliary type of histopathological differentiation, COX-2 expression did not significantly affect overall patient survival. In AC with intestinal differentiation COX-2 expression significantly predicted favourable survival (p = 0.003). In PC, COX-2 expression was significantly associated with high degree of differentiation (p = 0.002). COX-2 and LNR independently predicted good prognosis in a multivariate model.

Conclusions: COX-2 is overexpressed in pancreatic cancer, ampullary cancer and distal bile duct cancer and confers a survival benefit in all three cancer types. In pancreatic cancer, COX-2 overexpression is significantly associated with the degree of differentiation and independently predicts a favourable prognosis.

Show MeSH
Related in: MedlinePlus