S Aktas

Publications (5)7.74 Total impact

• Article: Future aspects of immunotherapy and gene therapy in neuroblastoma.

  S Aktas
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  ABSTRACT: Immunotherapy against cancer aims at stimulating the immune system or building an immune response against targeted tumor-associated antigens (TAAs). It was proposed theoretically as a potential therapy for cancer over a century ago but it became popular in the past two decades. Gene therapy represents a promising approach for reversing the neoplastic phenotype or driving tumor cells to self-destruction. Although survival rates of neuroblastoma (NB) with biologically favorable disease are greater than 90%, outcomes of patients with high risk disease are less than 40%. Stage 4 metastatic NB cases over 18 months of age are often incurable with multimodality chemotherapy regimens. In this article, translation of immuno-gene therapy strategies into clinical trials for NB are reviewed. Future aspects of immuno-gene therapy are discussed.
  Journal of B.U.ON.: official journal of the Balkan Union of Oncology 09/2009; 14 Suppl 1:S175-9. · 0.61 Impact Factor
• Article: Effect of apoptosis and response of extracellular matrix proteins after chemotherapy application on human breast cancer cell spheroids.

  G Oktem, S Vatansever, S Ayla, A Uysal, S Aktas, B Karabulut, A Bilir
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  ABSTRACT: Multicellular tumor spheroid (MTS) represents a three-dimensional structural form of tumors in laboratory conditions, and it has the characteristics of avascular micrometastases or intervascular spaces of big tumors. Recent studies indicate that extracellular matrix (ECM) proteins play a critical role in tumor metastasis, therefore normal and cancer cells require an ECM for survival, proliferation and differentiation. Doxorubicin and Docetaxel are widely used in the therapy of breast cancer, as well as in in vivo and in vitro studies. In this study, we examined the effect of apoptosis and proliferation of cells on the human breast cancer cell line, MCF-7, by using p53, bcl-2 and Ki67 gene expression, and the tendency to metastasis with extracellular matrix proteins, laminin and type IV collagen after chemotherapy in the spheroid model. The apoptotic cell death in situ was detected by TUNEL method. TUNEL-positive cells and positive immunoreactivities of laminin, type IV collagen, p53 and, bcl-2 were detected in the control group. There was no laminin and type IV collagen immunoreactivities in spheroids of drug groups. While TUNEL-positive cells and p53 immunoreactivity were detected in Docetaxel, Doxorubicin and Docetaxel/Doxorubicin groups, p53 immunoreactivity was not observed in the Docetaxel group. There was no bcl-2 immunoreactivity in either drug group. In addition, we did not detect Ki67 immunoreactivity in both control and drug treatment groups. However, the absence of Ki67 protein in MCF-7 breast multicellular tumor spheroids is possibly related to the cells in G0 or S phase. These chemotherapeutic agents may affect the presence of ECM proteins in this in vitro model of micrometastasis of spheroids. These findings suggest that the possible mechanism of cell death in Doxorubicin and Docetaxel/Doxorubicin treatment groups is related to apoptosis through the p53 pathway. However, we considered the possibility that there is another control mechanism for the Docetaxel group.
  Oncology Reports 03/2006; 15(2):335-40. · 1.84 Impact Factor
• Article: Tubular dysplasia and carcinoma in situ: precursors of renal cell carcinoma.

  K Yörükoğlu, S Aktas, M U Mungan, Z Kirkali
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  ABSTRACT: To identify the dysplastic changes in tubules adjacent to or remote from renal cell carcinoma (RCC) and to assess proliferating cell nuclear antigen (PCNA) expression of normal tubule and carcinoma cells. The study analyzed 62 kidneys with RCC that were removed by radical nephrectomy. Pathologic sections were stained with hematoxylin-eosin and evaluated for the presence of dysplasia. Sections that contained dysplasia were then stained by the avidin-biotin immunoperoxidase technique after epitope retrieval for PCNA. Dysplastic changes in normal kidney were identified in 14 cases (23%). Dysplastic changes were adjacent to the tumor in 10 cases. Dysplasia was adjacent to the tumor and diffuse in 6 cases (3 clear cell [CRCC], 2 chromophobe [ChRCC], 1 sarcomatoid RCC [SRCC]), adjacent to the tumor and focal in 4 cases (2 CRCC, 1 papillary RCC, 1 SRCC), remote and focal in 3 cases (1 granular RCC, 1 ChRCC, 1 SRCC), and remote and diffuse in 1 case (CRCC). The lesions represented a focus that could be defined as carcinoma in situ in 3 cases. PCNA immunostaining in dysplastic epithelia was more intense than that in normal tubules and was as intense or even more intense than that in carcinoma cells. Dysplasia of tubular epithelium is probably a biologic precursor of at least some RCC. Tubular dysplasia warrants further study as an important phase that will provide new insights into the pathogenesis, biologic behavior, and natural history of RCC. Its impact on the surgical management of small unilateral RCC needs to be investigated.
  Urology 05/1999; 53(4):684-9. · 2.43 Impact Factor
• Article: Volume-weighted mean nuclear volume in renal cell carcinoma.

  K Yörükoglu, S Aktas, C Güler, M Sade, Z Kirkali
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  ABSTRACT: Tumor grade and stage are the most important prognostic parameters for renal cell carcinoma (RCC). The value of histologic nuclear grading, however, is impaired by the inconsistency of pathologists' observations. Estimate of volume-weighted mean nuclear volume (MNV), based on a stereologic method, is correlated with prognosis of bladder, prostate, and endometrial cancer. In this study, we investigated the prognostic value of stereologic estimation of nuclear volume in RCC. This study included 62 patients with RCC who underwent radical nephrectomy between 1989 and 1996. Patients were evaluated in two groups: patients with locally advanced and/or metastatic disease were part of the poor prognosis group and patients with localized disease were part of the good prognosis group. Unbiased estimates of MNV were compared with histologic grade, tumor stage, and growth pattern according to Thoenes classification. Group means were compared using the nonparametric Kruskal-Wallis one-way analysis of variance. Univariate analysis of the data was performed for MNV and time to death, metastasis, local recurrence, and disease-free survival by paired sample t test. For categorical variables, Pearson's correlation test was used for statistical analysis. There was no correlation between MNV and patient sex, age, tumor stage, and growth pattern. MNV showed a trend to be higher in sarcomatoid and chromophilic cell types than in chromophobe and clear cell types (P < 0.05). MNV values were significantly higher with increasing grades but no MNV cutoff levels could be defined. The MNV values were not different between localized and locally advanced and/or metastatic disease. Our results indicate that estimates of MNV are not useful for predicting disease outcome. Further studies are needed to set up reproducible intervals of tumor dedifferentiation that could be carried out in routine practice for predicting progression.
  Urology 07/1998; 52(1):44-7. · 2.43 Impact Factor
• Article: Ameloblastic fibro-odontoma of the maxilla: case report.

  E Ozer, U Pabuccuoglu, U Gunbay, S Sarioglu, S Aktas
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  ABSTRACT: A 7-year-old girl presenting with proptosis was referred for management of a partially ossified mass occupying the right maxillary sinus. A complete enucleation was performed after the histological diagnosis given in frozen section as ameloblastic fibro-odontoma. Ameloblastic fibro-odontomas occur predominantly in children and young adults. The mandibular molar-ramus area is the favored location and radiographically, these lesions are well circumscribed and lucent-opaque. The tumor mass is composed of a myxoid connective tissue with strands of odontogenic epithelium and differentiated tissues such as enamel and dentin. The treatment is a conservative surgical procedure due to benign biological behavior.
  The Journal of clinical pediatric dentistry 02/1997; 21(4):329-31. · 0.44 Impact Factor