ISSN: 1300-7777 E-ISSN: 1308-5263
Determination of apoptosis, proliferation status and O6-methylguanine DNA methyltransferase methylation profiles in different immunophenotypic profiles of diffuse large B-cell lymphoma [Turk J Hematol]
Turk J Hematol. 2011; 28(1): 15-26 | DOI: 10.5152/tjh.2010.37  

Determination of apoptosis, proliferation status and O6-methylguanine DNA methyltransferase methylation profiles in different immunophenotypic profiles of diffuse large B-cell lymphoma

Nilay Şen Türk1, Nazan Özsan2, Vildan Caner3, Nedim Karagenç3, Füsun Düzcan4, Ender Düzcan1, Mine Hekimgil2
1Department Of Pathology, Faculty Of Medicine, Pamukkale University, Denizli, Turkey
2Department Of Pathology, Faculty Of Medicine, Ege University, İzmir, Turkey
3Department Of Medical Biology, Faculty Of Medicine, Pamukkale University, Denizli, Turkey
4Department Of Medical Genetics, Faculty Of Medicine, Pamukkale University, Denizli, Turkey

OBJECTIVE: Our aim was to investigate the expression of apoptosis-associated proteins (bcl-2, bcl-xl, bax, bak, bid), apoptotic index (AI) and proliferation index (PI) in germinal center B-cell-like immunophenotypic profile (GCB) and non-GCB of diffuse large B-cell lymphoma (DLBCL).
METHODS: The methylation status of the promoter region of O6-methylguanine-DNA yerine O6-methylguanine-DNA methyltransferase (MGMT) gene and its relation with immunophenotypic differentiation of DLBCLs were also investigated. 101 cases were classified as GCB (29 cases) or non-GCB (72 cases). Apoptosis-associated proteins and PI were determined by IHC, and TUNEL method was used to determine AI. MGMT methylation analysis was performed by real-time PCR.
RESULTS: The PI was significantly higher in GCB compared with non-GCB (p=0.011). Percentage of cells stained with bcl-6 was positively correlated with the percentage of cells expressing bcl-2 (p=0.023), AI (p=0.006) and PI (p<0.001), while a significant negative correlation was observed with the percentage of cells expressing bax (p=0.027). The percentage of cells stained with MUM1 showed a significantly positive correlation with the percentage of cells expressing bcl-xl (p=0.003), bid (p=0.002), AI (p<0.001), and PI (p=0.001). MGMT methylation analysis was performed in 95 samples, and methylated profile was found in 31 cases (32.6%). GCB was found in 6 cases (22.2%) and non-GCB was determined in 25 cases (36.8%) out of 31 with MGMT methylated samples. There was no significant association between MGMT methylation status and immunophenotypic profiles (p=0.173).
CONCLUSION: These results suggest that bcl-6 protein expression may be responsible for the high PI in GCB. Additionally, we found that apoptosis-associated proteins were not significantly associated with immunophenotypic profiles.

Keywords: Lymphoma, B-cell, apoptosis, proliferation, methylation


Diffüz büyük B-hücreli lenfomanın farklı immünofenotipik profillerinde apoptozis, proliferasyon durumu ve O6-metilguanin DNA metiltransferaz metilasyon profillerinin tespiti

Nilay Şen Türk1, Nazan Özsan2, Vildan Caner3, Nedim Karagenç3, Füsun Düzcan4, Ender Düzcan1, Mine Hekimgil2
1Pamukkale Üniversitesi Tıp Fakültesi Patoloji Anabilim Dalı, Denizli
2Ege Üniversitesi Tıp Fakültesi Patoloji Anabilim Dalı, İzmir
3Pamukkale Üniversitesi Tıp Fakültesi Tıbbi Biyoloji Anabilim Dalı, Denizli
4Pamukkale Üniversitesi Tıp Fakültesi Tıbbi Genetik Anabilim Dalı, Denizli

AMAÇ: Diffüz büyük B-hücreli lenfoma (DBBHL)’nın germinal merkez B-hücresi benzeri (GCB) ve non-GCB profillerinde apoptozis-ilişkili proteinlerin (bcl-2, bcl-xl, bax, bak, bid) ekspresyonunu, apoptotic indeksi (AI) ve proliferasyon indeksi (PI)’ni araştırmaktır. Ayrıca, O6-methylguanine-DNA methyltransferase (MGMT) geninin promoter bölgesinin metilasyon durumunu ve onun DBBHL’nın immünofenotipik diferansiyasyonuyla ilişkisini araştırmaktır.
YÖNTEMLER: 101 olgu GCB (29 olgu) ve non-GCB (72 olgu) olarak sınıflandırıldı. Apoptozis-ilişkili proteinler ve PI immünohistokimyasal olarak saptandı ve TUNEL yöntemi AI’i belirlemek için kullanıldı. MGMT metilasyon analizi, real-time PCR ile gerçekleştirildi.
BULGULAR: : PI, non-GCB ile karşılaştırıldığında GCB’de anlamlı şekilde yüksek saptandı (p=0.011). Bcl-6 ile p: PI, non-GCB ile karşılaştırıldığında GCB’de anlamlı şekilde yüksek saptandı (p=0.011). Bcl-6 ile pozitif boyanan hücrelerin yüzdesi bcl-2 (p=0.023), AI (p=0.006), ve PI (p<0.001) eksprese eden hücrelerin yüzdesi ile pozitif şekilde korele iken, bax eksprese eden hücrelerin yüzdesi ile negatif korelasyon gözlendi (p=0.027). MUM1 ile boyanan hücrelerin yüzdesi bcl-xl (p=0.003), bid (p=0.002), AI (p<0.001) ve PI (p=0.001) eksprese eden hücrelerin yüzdesi ile anlamlı şekilde pozitif korelasyon gösterdi. MGMT metilasyon analizi 95 örneğe uygulandı ve metilasyon profili 31 olguda (32.6%) saptandı. 31 MGMT metile örnekten 6 olgunun (22.2%) GCB ve 25 olgunun (36.8%) non-GCB olduğu belirlendi. MGMT metilasyon durumu ve immünofenotipik profiler arasında anlamlı ilişki saptanmadı (p=0.173).
SONUÇ: Bu bulgular, bcl-6 protein ekspresyonunun GCB’de yüksek PI’inden sorumlu olabileceğini öne sürmektedir. Ek olarak, apoptozis-ilişkili proteinlerin immünofenotipik profilerle anlamlı ilişki göstermediğini saptadık.

Anahtar Kelimeler: Büyük B-hücreli lenfomalarda apoptosis ve proliferasyon


Nilay Şen Türk, Nazan Özsan, Vildan Caner, Nedim Karagenç, Füsun Düzcan, Ender Düzcan, Mine Hekimgil. Determination of apoptosis, proliferation status and O6-methylguanine DNA methyltransferase methylation profiles in different immunophenotypic profiles of diffuse large B-cell lymphoma. Turk J Hematol. 2011; 28(1): 15-26

Corresponding Author: Nilay Şen Türk, Türkiye


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