Browsing by Author "Yigitturk, Gurkan"

Now showing 1 - 7 of 7

Comparison of Cell Cycle Components, Apoptosis and Cytoskeleton-Related Molecules and Therapeutic Effects of Flavopiridol and Geldanamycin on the Mouse Fibroblast, Lung Cancer and Embryonic Stem Cells
(Sage Publications Ltd, 2016) Aktug, Huseyin; Acikgoz, Eda; Uysal, Aysegul; Oltulu, Fatih; Oktem, Gulperi; Yigitturk, Gurkan; Cetintas, Vildan Bozok
Similarities and differences in the cell cycle components, apoptosis and cytoskeleton-related molecules among mouse skin fibroblast cells (MSFs), mouse squamous cell lung carcinomas (SqCLCs) and mouse embryonic stem cells (mESCs) are important determinants of the behaviour and differentiation capacity of these cells. To reveal apoptotic pathways and to examine the distribution and the role of cell cycle-cell skeleton comparatively would necessitate tumour biology and stem cell biology to be assessed together in terms of oncogenesis and embryogenesis. The primary objectives of this study are to investigate the effects of flavopiridol, a cell cycle inhibitor, and geldanamycin, a heat shock protein inhibitor on mouse somatic, tumour and embryonic stem cells, by specifically focusing on alterations in cytoskeletal proteins, cell polarity and motility as well as cell cycle regulators. To meet these objectives, expression of several genes, cell cycle analysis and immunofluorescence staining of intracellular cytoskeletal molecules were performed in untreated and flavopiridol- or geldanamycin-treated cell lines. Cytotoxicity assays showed that SqCLCs are more sensitive to flavopiridol than MSFs and mESCs. Keratin-9 and keratin-2 expressions increased dramatically whereas cell cycle regulatory genes decreased significantly in the flavopiridol-treated MSFs. Flavopiridol-treated SqCLCs displayed a slight increase in several cell cytoskeleton regulatory genes as well as cell cycle regulatory genes. However, gene expression profiles of mESCs were not affected after flavopiridol treatment except the Cdc2a. Cytotoxic concentrations of geldanamycin were close to each other for all cell lines. Cdkn1a was the most increased gene in the geldanamycin-treated MSFs. However, expression levels of cell cytoskeleton-associated genes were increased dramatically in the geldanamycin-treated SqCLCs. Our results revealing differences in molecular mechanisms between embryogenesis and carcinogenesis may prove crucial in developing novel therapeutics that specifically target cancer cells.
Deneysel Diabet Modeli Oluşturulan Farelerde Tirozin Kinaz İnhibitör Uygulanımının Testis Dokusu Üzerine Olan Etkilerinin Pluripotensi Kapasitesi ve Hücre Adezyonu Özelinde Araştırılması
(2017) Oktem, Gulperi; Demir, Kenan; Aktug, Huseyin; Yigitturk, Gurkan; Yavaşoğlu, Altuğ; Özdedeli, Kaan; Açıkgöz, Eda
Amaç: Tirozin kinaz inhibisyonunun diyabet etkisi altındaki testis dokusu üzerine göstereceği etkileri araştırmaktır. Gereç ve Yöntem: Çalışmamızda 31 adet CD1 türü erkek fare kullanıldı ve dört gruba ayrıldı: Grup 1'de (kontrol grubu) 7, Grup 2'de tirozin kinaz inhibitörü uygulanan 7, Grup 3'te diyabetik ve SF uygulanan 8, Grup 4'te diyabet + tirozin kinaz inhibitörü uygulanan 9 denek hayvanı yer aldı. Grup 1'de herhangi bir uygulama yapılmadı. Grup 2'deki farelere 3 hafta boyunca tirozin kinaz inhibitörü verildi. Diyabet oluşturulması için 0.1mol/L tek doz streptozotosinin intraperitoneal olarak verildi. 250 mg/dL ve üzeri kan glikoz seviyesi diyabetik olarak kabul edildi. Deneysel diyabet modeli oluşturulan farelere 1 hafta beklendikten sonra, Grup 3'e SF, Grup 4'e 3 hafta boyunca tirozin kinaz inhibitörü verildi. Sonunda tüm denek hayvanları anestezi altında sakrifiye edilerek histopatolojik inceleme için testis dokuları alındı. İstatistiksel analiz için tek yönlü varyans analizi (ANOVA) testi yapıldı, 0.05'ten küçük p değerleri, istatistiksel olarak anlamlı kabul edildi. Bulgular: Testis dokusu histopatolojik olarak incelendiğinde deneysel diyabete bağlı olarak seminifer tübülün germ hücre serilerinde kayıp, hücre bütünlüklerinde ise bozulma saptandı. Sonuç: Bu çalışma, diyabetin testiste germ hücre serilerinde sayısal olarak azalmaya ve hücre adezyon mekanizmasında bozulmaya yol açtığını göstermektedir. Tirozin kinaz inhibitörü uygulamasının, bu hasarlanmada tamir edici etkisinin olduğu düşünülmektedir. Bu hasarın tedavisinin derecesi, uygulanan tirozin kinaz inhibitörünün dozu ve süresine bağlı olarak farklılık gösterebilmektedir. Ancak, klinik diyabet uygulamalarında tirozin kinaz inhibitörü kullanılabilmesi için bu konuda moleküler çalışma sayılarının artışına ihtiyaç vardır.
Double Hit Strategy: Removal of Sialic Acid From the Dendritic Cell Surface and Loading With Cd44+/Cd24- Cell Lysate Inhibits Tumor Growth and Metastasis by Targeting Breast Cancer Stem Cells
(Elsevier, 2022) Acikgoz, Eda; Duzagac, Fahriye; Guven, Ummu; Yigitturk, Gurkan; Kose, Timur; Oktem, Gulperi
Cancer stem cells (CSCs), which represent the root cause of resistance to conventional treatments, recurrence, and metastasis, constitute the critical point of failure in cancer treatments. Targeting CSCs with dendritic cell (DC)-based vaccines have been an effective strategy, but sialic acids on the surface of DCs limit the interaction with loaded antigens. We hypothesized that removal of sialic acid moieties on immature DCs (iDCs) could significantly affect DC-CSC-antigen loading, thereby leading to DC maturation and improving immune recognition and activity. The lysate of CD44+/CD24-/low breast CSCs (BCSCs) was pulsed with sialidase-treated DCs to obtain mature dendritic cells (mDCs). The roles of cytoskeletal elements in antigen uptake and dendritic cell maturation were determined by immunofluorescence staining, flow cytometry, and cytokine measurement, respectively. To test the efficacy of the vaccine in vivo, CSCs tumor-bearing mice were immunized with iDC or mDC. Pulsing DCs with antigen increased the expression levels of actin, gelsolin, talin, WASp, and Arp2, especially in podosome-like regions. Compared with iDCs, mDCs expressed high levels of CD40, CD80, CD86 costimulatory molecules and increased IL-12 production. Vaccination with mDC: i) increased CD8+ and CD4 + T-cell numbers, ii) prevented tumor growth with anti-mitotic activity and apoptotic induction, iii) suppressed metastasis by decreasing Snail, Slug, and Twist expressions. This study reveals for the first time that sialic acid removal and loading with CSC antigens induces significant molecular, morphological, and functional changes in DCs and that this new DC identity may be considered for future combined immunotherapy strategies against breast tumors.
Effects of Flavopiridol on Critical Regulation Pathways of Cd133high Lung Cancer Stem Cells
(Lippincott Williams & Wilkins, 2016) Cetintas, Vildan Bozok; Acikgoz, Eda; Yigitturk, Gurkan; Demir, Kenan; Oktem, Gulperi; Kaymaz, Burcin Tezcanli; Aktug, Huseyin
Background:Flavopiridol a semisynthetic flavone that inhibits cyclin-dependent kinases (CDKs) and has growth-inhibitory activity and induces a blockade of cell-cycle progression at G1-phase and apoptosis in numerous human tumor cell lines and is currently under investigation in phase II clinical trials. Cancer stem cells (CSCs) are comprised of subpopulation of cells in tumors that have been proposed to be responsible for recurrence and resistance to chemotherapy. The aim of the present study was to investigate the effects of flavopiridol in cancer stem cell cytoskeleton, cell adhesion, and epithelial to mesenchymal transition in CSCs.Methods:The cells were treated with flavopiridol to determine the inhibitory effect. Cell viability and proliferation were determined by using the WST-1 assay. Caspase activity and immunofluorescence analyses were performed for the evaluation of apoptosis, cell cytoskeleton, and epithelial-mesenchymal transition (EMT) markers. The effects of flavopiridol on the cell cycle were also evaluated. Flow cytometric analysis was used to detect the percentages of CSCs subpopulation. We analyzed the gene expression patterns to predict cell cycle and cell cytoskeleton in CSCs by RT-PCR.Results:Flavopiridol-induced cytotoxicity and apoptosis at the IC50 dose, resulting in a significant increase expression of caspases activity. Cell cycle analyses revealed that flavopiridol induces G1 phase cell cycle arrest. Flavopiridol significantly decreased the mRNA expressions of the genes that regulate the cell cytoskeleton and cell cycle components and cell motility in CSCs.Conclusion:Our results suggest that Flavopiridol has activity against lung CSCs and may be effective chemotherapeutic molecule for lung cancer treatment.
The Neuro-Restorative Effect of Adipose-Derived Mesenchymal Stem Cell Transplantation on a Mouse Model of Diabetic Neuropathy
(Taylor & Francis Ltd, 2022) Yigitturk, Gurkan; Erbas, Oytun; Karabay Yavasoglu, Nefise Ulku; Acikgoz, Eda; Buhur, Aylin; Gokhan, Aylin; Yavasoglu, Altug
Diabetic neuropathy (DN) is the most common degenerative complication associated with Diabetes Mellitus. Despite widespread awareness about DN, the only effective treatments are blood glucose control and pain management. The aim of the current study was to determine the effect of intramuscular adipose-derived mesenchymal stem cell (AMSC) transplantation on sciatic nerves in DN using EMG and histological analyses. A total of 27 mice were randomly divided into three groups: control group, DN group and AMSC group. In EMG, CMAP amplitude in the sciatic nerves was lower, but distal latency was higher in the DN group compared with the control group. CMAP amplitude in the sciatic nerves was higher in the AMSC group compared with the DN group. Distal latency in the sciatic nerve was lower in the AMSC group compared with the DN group. Histologic examination of the tissues in the animals treated with AMSC showed a remarkable improvement in microscopic morphology. Fluorescence microscopy analyses demonstrated that intramuscularly transplanted AMSC was selectively localized in the sciatic nerves. Transplantation of AMSC increased protein expression of S100, cdk2, NGF and DHH, all of which, interfered with DN onset in sciatic nerves. The findings of the present study suggest that AMSC transplantation improved DN through a signal-regulatory effect on Schwann cells, neurotrophic actions and restoration of myelination.
Prostat Kanseri Hücreleri'nde D-amino Nöraminik Asidin Gangliozid'e Spesifik Bağlanmasının Çalışılması
(2023) Yigitturk, Gurkan; Rouhrazi, Hadi; Aktug, Huseyin; Güler, Günnur; Demir, Kenan; Acıkgoz, Eda
Amaç: Bu çalışmanın amacı, insan D-Amino Nöraminik Asid’inin (KDN, 2-keto-3-deoksi-D-glisero-D galakto-nononik asit) hücresel bağlanma bölgesini araştırmaktır. KDN molekülü, sialik asit ailesinin bir üyesidir ve kanser hücrelerinde ekspresyonu artar. KDN'nin alabalık sperminde Monosialodihexosyl Gangliosid’e (GM3) bağlandığı gösterilmiştir. Gereç ve Yöntem: Bu çalışmada bir prostat kanseri hücre dizisi (DU145) kullanıldı. Her deney grubu; Kontrol, Glukosilseramid sentaz (GCS) enzim inhibitörü Genz-123346 ile tedavi edilen ve GM3 sentez inhibitörü Triptolid ile tedavi edilen olmak üzere 3 gruba ayrıldı. Her grup, GM3, Disialosyllactosylceramide (GD3) ve KDN için immünositokimyasal yöntem kullanılarak boyandı. Tedaviden sonra hücresel değişikliklerin sağlaması Fourier Transform Infrared (FTIR) Spektroskopi analizi ile yapıldı. Bulgular: Tedavi edilmeyen 1 numaralı hücre grubu, GM3, GD3 ve KDN ile pozitif boyandı ve GCS enzimi, sadece KDN ile pozitif boyanan 2 numaralı hücrelerin Genz-123346 grubuyla bloke edildi. Ayrıca, GD3 sentaz inhibitörü Triptolide ile muamele edilmiş 3 numaralı hücre grubu, GM3 ve KDN ile pozitif boyandı. FTIR ölçümleri Triptolide ile apoptotik özellikler gösterirken, Genz-123346 hücre canlılığı üzerinde olumsuz bir etkiye sahip değildi. Şeker yapılarında azalma ortaya çıktı ve immunositokimyasal boyama ile elde ettiğimiz sonuçlar FTIR ile pekiştirildi. Sonuç: KDN'nin yerinin belirlenmesi, kanser tedavisi araştırmaları için yeni hedeflerin seçilmesi açısından önemlidir. KDN'nin GM3 inhibisyonu ve GD3 inhibisyonu tarafından inhibe edilmediği gösterilmiştir. KDN, GM3 üzerinde olabileceği gibi farklı yerlere de bağlanabilir veya serbest halde olabilir. Bu çalışmada yalnızca salt GM veya GD serisindeki gangliozidlerden herhangi birine bağlanmayacağı ortaya konulmuştur.
Repression of the Notch Pathway Prevents Liver Damage in Streptozotocin-Induced Diabetic Mice
(Via Medica, 2017) Acikgoz, Eda; Aktug, Huseyin; Yigitturk, Gurkan; Demir, Kenan; Guven, Ummu; Duzagac, Fahriye; Oktem, Gulperi
Introduction. Sunitinib is an oral inhibitor of vascular endothelial growth factor that is used to treat a variety of cancer. There are limited data regarding the effect of sunitinib on diabetes. In the liver, Notch signaling plays an important role in liver tissue development and homeostasis and its dysfunction is associated with liver pathologies. The aim of the present study is to investigate the effects of sunitinib on streptozotocin (STZ)-induced diabetic liver in mice models. Material and methods. An experimental diabetes mellitus (DM) model was created in 28 male CD-1 mice. Twenty-eight male CD-1 mice divided in four groups (n = 7 each) were used; control mice (C), control mice treated with sunitinib (C + S), diabetic mice (DM), and diabetic mice treated with sunitinib (DM + S) for four weeks. The histopathological changes in the liver were examined by histochemistry and immunohistochemistry. Immunoreactivity of Notch1, Jagged1, DLL-1 and VEGF were evaluated in control and diabetic mice after sunitinib treatment. Results. The significant morphological changes in the liver were mostly seen in hepatocytes that were hypertrophied in the DM mice, with an increased amount of eosinophilic granules; moreover, some hepatocytes contained empty vacuole-like structures. The livers of the DM mice revealed increased deposition of collagen fibers. After sunitinib treatment the hepatocytes and hepatic lobules had almost similar morphology to control mice. The immunoreactivities of Notch1, Jagged1, DLL-1 and VEGF in hepatocytes were significantly lower in the DM group when compared with the C, DM + S and C + S group treated with sunitinib. Conclusions. These results suggest that sunitinib effectively protects the liver from diabetes-induced damage through the inhibition of the Notch pathway.