Browsing by Author "Yigittürk, G"

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    A comparison of cancer stem cell markers and nonclassical major histocompatibility complex antigens in colorectal tumor and noncancerous tissues
    Özdemir, RBÖ; Özdemir, AT; Oltulu, F; Kurt, K; Yigittürk, G; Kirmaz, C
    Colorectal carcinoma (CRC) is one of the most fatal types of cancer in both women and men, and, unfortunately, patients are often diagnosed at an advanced stage. Cancer stem cells (CSCs) are associated with poor prognosis, metastasis, and recurrence, as well as chemotherapy and radiotherapy resistance. Therefore, different treatment alternatives are needed to facilitate the elimination of CSCs. One such approach is immunotherapy; however, tumor cells can evade immune cells by alteration of the expression patterns of human leukocyte antigens (HLA). In this study, we immunohistochemically investigated the expression patterns of CSC-specific markers CD44, CD133, Nanog, and Oct3/4, and immunosuppressive molecules HLA-G and -E in advanced CRC tumor tissues and noncancerous colon biopsies. We found significantly increased CD44, Nanog, Oct3/4, HLA-G, and HLA-E expression in the CRC tumor tissues compared with the noncancerous colon biopsies. These findings suggest that some tumor cells may be CSC-like and that the increased expression of HLA-G and HLA-E may be considered as an immune-evasive adaptation. Therefore, the nonclassical major histocompatibility complex class Ib antigens HLA-G and HLA-E may be potential targets in the elimination of CRC-CSCs. However, more detailed studies are required to support our findings. (C) 2016 Elsevier Inc. All rights reserved.
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    An immunoevasive mechanism for cancer stem cells: increased expressions of HLA-G and HLA-E
    Özdemir, RBO; Özdemir, AT; Kirmaz, C; Oltulu, F; Yigittürk, G; Kurt, K
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    The Expressions of Cancer Stem Cell Markers and Non-classical HLA antigens in Breast Tumors
    Özdemir, RBÖ; Özdemir, AT; Oltulu, F; Kurt, K; Yigittürk, G; Kirmaz, C
    Objective: There is a strong relationship between the cancer stem cells (CSCs) and poor prognosis, metastasis and recurrence. In addition to this CSCs are resistant to chemotherapy and radiotherapy. Therefore, current treatment approaches may be ineffective to elimination of CSCs. The tumor cells have various adaptations for escaping from immune cells. The human leukocyte antigen (HLA)-G, which expressions restricted with fetal tissues and HLA-E are kind of tumor immune evasive adaptations. In this study, we aimed to investigate the relationship between the CSCs and immune evasive adaptations of breast tumors. Methods: We immunohistochemically evaluated that the expressions of cluster of differentiation (CD) 44, CD133, Homeobox protein Nanog, octamer-binding transcription factor (Oct) 3/4, HLA-G and HLA-E in the advanced stage breast cancer tissues (n= 10) and the non-malignant breast biopsies (n= 10). Results: We detected that the significantly increased expressions of especially Nanog (p< 0.001) and also CD44 (p< 0.001), CD133 (p< 0.001) and Oct3/4 (p< 0.001) in the advanced stage breast tumor group compared with non-malignant breast biopsies group, but the HLA-G (p< 0.001) and HLA-E (p< 0.001) decreased. Conclusion: These findings suggested that, malignant breast tumors may have CSC-like cells, and these cells may play role for occurring malignant behavior. To proliferation and tumor formation, the immune evasion is essential for both of malignant and benign tumors. Higher expressions of HLA-G and HLA-E may be an indication that the non-malign tumors more immune evasive than the malign tumors. However, further prospective studies are needed to confirm our findings.