Investigation of the relationship between stem cell markers CD133 and CXCR4/CXCL12 complex and poor prognosis in Pancreatic Ductal Adenocarcinomas

Introduction and Purpose: Exocrine pancreatic ductal adenocarcinoma (PDAC) accounts for approximately 90% of all pancreatic malignancies. PDAC has a high mortality rate and 5-year survival rate is 7%. It is expected to become the second cause of cancer-related deaths by 2030. The primary treatment for this aggressive malignancy is surgical resection. Unfortunately, due to the low early diagnosis rate, only 10-20% of patients are resectable. Even in operable cases, 5-year survival is low. One of the reasons for this poor prognosis is the high resistance of PDAC to chemotherapy. One of the underlying causes of chemotherapy resistance is cancer stem cells (CSC) and chemokines. The CSC`s are responsible for tumor recurrence after initiation of the tumor, rapid growth with self-regeneration capacity, resistance to treatment, formation of metastases and recurrence after adjuvant therapy. CSC has been found in many malignant tumors, including pancreatic cancer. CD133 expression has been identified in pancreatic CSCs. Chemokines are the cytokines that regulate various physiological and immune processes and also increase the growth, proliferation and metastasis of tumor cells. Chemokines display their above functions by binding to and activating chemokine receptors in the cell membrane. Chemokine receptor type 4 (CXCR4) is the suitable receptor for chemokine ligand 12. The CXCL12/CXCR4 complex is one of the most prominent chemokine moderators that make up the tumor microenvironment. The CXCR4/CXCL12 chemokine complex has been found to play an important role in pancreatic cancer development, invasion, metastasis and treatment resistance. Materials and Methods: 80 cases with pancreatic cancer treated with radical surgery at Bezmiâlem Vakıf University Hospital between January 2012 and December 2019 were included in the study. Archive files of the cases were examined. Of the cases, 56 were male and 24 were female, with an average age of 65.3 (38-84). Among the 80 cases, the tumor was located in the head of the pancreas, in 70 cases, and in the remaining 10 cases in the body/tail of the pancreas. All cases were diagnosed as xv pancreatic ductal adenocarcinoma. The cases were divided into two groups based on the 2017 AJCC 8th edition. Among the 22 cases in IA, IB and IIA stages that did not show metastasis of the first group lymph node. The II group consisted of 58 cases with stage IIB and III with lymph node metastasis. To evaluate the correlation between CXCR4, CXCL12 and CD133, the data were analyzed with İBM SPSS statistical 22.0 package program. The distribution of categorical changes was examined by Chi-square test. Median (min-mac), frequency and percentage values were given as descriptive statistics. p <0,05 was considered statistically significant. Results: Immunhistochemically stained preparations of the cases were examined under a light microscope. In both groups, no staining was detected with CXCR4 and CXCL12 in tumor adjacent and tumor-free pancreatic stroma; and with CD133 in tumor periphery and tumor-free pancreatic tissue. Cells with cytoplasmic and cytomembranous staining were identified as positive CXCR4 and CXCL12 antibody in tumor stroma and metastatic lymph node stroma. The presence of cytomembranous and cytoplasmic staining with CD133 in tumor cells in the lymph node with tumor and metastases was also considered positive. In the first group, CXCR4 and CXCL12, evaluated in the tumor stroma in 22 cases, showed co-expression in 41% of cases. In 13,6% of cases, all three biomarkers (CXCR4, CXCL12, CD133) were positive. It was observed that CXCR4, CXCL12 and CD133 were not expressed alone. No any staining was observed in 45,5% of cases. In the second group which tumor stroma and tumor evaluated in 58 cases; CD133 in 1,7%; CXCL12 in 3,4%; CXCR4 in 5,2%; CXCL12+CXCR4 in 17%; CD133+CXCL12+CXCR4 in 36,2% and CD133+CXCR4 in 10,3% of cases was expressed. No any staining was observed in 26,2% of cases. When two groups were compared, there was no statistically significant difference in CD133, CXCL12 and CXCR4 biomarkers expressing alone and in coexpression of CD133/CXCR4. However, there were statistically significant differences between the two groups in coexistence of CXCL12/CXCR4 and CD133/CXCL12/CXCR4. In the second group, CXCL12 in 12%, CXCR4 in 1,7%, CXCL12+CXCR4 in 27,6%, CD133+CXCL12+CXCR4 in 36,2%, CD133+CXCR4 in 6,9% of cases was xvi expressed in metastatic lymph nodes and stroma of the metastatic lymph node. No staining was observed in 15,6% of cases. When tumor and metastatic lymph node were compared in second group, there was no statistically significant difference in the expression of CD133 and CXCL12 alone. However, a statistically significant difference was found in expression CXCR4 alone and in co-expressions of CXCL12/CXCR4; CD133/CXCR4; and CD133/CXCL12/CXCR4. Conclusion: These findings suggest that the CD133, CXCL12 and CXCR4 axis may be a prognostic marker and may provide new targets for combined therapies in PDAC treatment.