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Dive into the research topics where Gokhan S. Kilic is active.

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Featured researches published by Gokhan S. Kilic.


European Journal of Cancer Prevention | 2008

From endometrial hyperplasia to endometrial cancer: insight into the biology and possible medical preventive measures.

Melih Cem Boruban; Kadri Altundag; Gokhan S. Kilic; Josef Blankstein

Controversies are still seen in the histological differential diagnosis of hyperplasia and well-differentiated endometrial carcinoma. Prediction of endometrial cancer in patients with hyperplasia with atypia, with the available markers has not been reliable yet. Hence these patients require more attention in the clinical management. Endometrial hyperplasia is proliferation of endometrial glands resulting in a higher gland : stroma ratio. Cytological atypia, which may progress to or co-exist with endometrial cancer and other pathological changes, result from estrogen stimulation unopposed by progesterone. Biomarkers whose expression is altered in cases of endometrial hyperplasia or cancer such as progesterone receptor, insulin-like growth factor I, retinaldehyde dehydrogenase type II, and secreted frizzled-related protein 4, seem to be promising to use as early-stage tumor markers. Mutation of PTEN is present in 83% of endometrial adenocarcinoma cases, making it the most frequent early molecular genetic alteration in type 1 endometrial tumors, which are generally associated with hyperplasia. p53 gene mutation is not found in endometrial hyperplasia, but researchers have detected this mutation in 20% of cases of endometrial carcinoma and 90% of cases of serous endometrial tumors. Cyclooxygenase-2 is important in tumorogenic transformation of hyperlasia. Expression of cyclooxygenase-2 decreases apoptosis, increases angiogenesis, and is related to invasiveness. Cyclooxygenase-2 expression increases significantly in cases of well-differentiated endometrial adenocarcinoma. Prostaglandin E2 is known to regulate aromatase gene expression and is the product of cyclooxygenase-2. The data about aromatase inhibitors are promising; in breast cancer patients, treatment with tamoxifen induces uterine abnormalities as early as 3 months after the initiation of therapy. In contrast, these abnormalities are not seen in patients who receive aromatase inhibitors and switched therapy after tamoxifen withdrawal may reverse tamoxifen-associated endometrial thickening.


American Journal of Obstetrics and Gynecology | 2000

Expression of dioxin-related transactivating factors and target genes in human eutopic endometrial and endometriotic tissues

Serdar E. Bulun; Khaled Zeitoun; Gokhan S. Kilic

OBJECTIVE Although an association between dioxin exposure and endometriosis has been proposed, the effects of this environmental toxin on human endometriosis are not known. To understand the potential underlying molecular mechanisms we studied the expressions of cytochrome P-450 genes (CYP1A1, CYP1A2, and CYP1B1 ), which are induced by dioxin, and the expressions of cytosolic receptor for dioxin, aryl hydrocarbon receptor, and its nuclear translocator, aryl hydrocarbon receptor nuclear translocator protein, in endometriotic and eutopic endometrial tissues. STUDY DESIGN Levels of transcripts of CYP1A1, CYP1A2, CYP1B1, aryl hydrocarbon receptor, and aryl hydrocarbon receptor nuclear translocator protein were determined by a quantitative reverse transcriptase-polymerase chain reaction and Southern blot assay in total ribonucleic acid samples from endometriotic and eutopic endometrial tissues. Eutopic endometrial tissue samples (n = 33) and endometriotic tissue samples (n = 10) were obtained at the time of uterine curettage and laparoscopy from disease-free women and from patients with endometriosis. Portions of these eutopic endometrial and endometriotic tissues were obtained simultaneously from the same patients (n = 8 pairs of samples). Levels of transcripts of CYP1A1, CYP1A2, CYP1B1, aryl hydrocarbon receptor, and aryl hydrocarbon receptor nuclear translocator protein were determined in endometrial and endometriotic tissues during follicular and luteal phases of the cycle and in cultured endometriotic stromal cells treated with forskolin, phorbol diacetate, medroxyprogesterone acetate,and serum. RESULTS Transcripts of dioxin receptor, its nuclear translocator, and two dioxin-induced target genes (CYP1A2 and CYP1B1) were demonstrated during follicular and luteal phases of the cycle in both eutopic endometrial tissues and tissues affected by pelvic endometriosis, with no readily detectable differences between these tissues. On the other hand, levels of transcripts of another dioxin-induced gene, CYP1A1, were found to be strikingly higher in endometriotic tissues than in the eutopic endometrium. Mean levels in endometriotic tissues were 8.7 times those found in eutopic endometrium. Various hormonal treatments of endometriotic stromal cells did not significantly alter these levels. CONCLUSION We demonstrated for the first time the expression of dioxin-related transcription factors aryl hydrocarbon receptor and aryl hydrocarbon receptor nuclear translocator protein and target genes CYP1A1, CYP1A2, and CYP1B1 in endometriotic tissues and stromal cells. Strikingly elevated CYP1A1 transcripts in endometriosis may give rise to significantly increased P-4501A1 enzyme activity and thus promote the development and growth of endometriosis by either activating procarcinogens or inducing the formation of catechol estrogens or both. In fact, the proposed link between dioxin exposure and endometriosis may be explained in part by the up-regulation of the CYP1A1 gene expression in endometriotic tissues.


Reproductive Biomedicine Online | 2008

Treatment of symptomatic uterine leiomyoma with letrozole

Bilgin Gurates; Cem Parmaksiz; Gokhan S. Kilic; Husnu Celik; Selahattin Kumru; Mehmet Simsek

Uterine leiomyomas are the most common benign tumours of the female genital tract, often necessitating hysterectomy. The most common symptoms are dysmenorrhoea, menorrhagia, infertility and abortion. Ovarian hormones seem to play an essential role in pathogenesis, and deprivation of ovarian oestrogen causes leiomyomas to shrink significantly. The purpose of this study was to evaluate the effects of the non-steroidal aromatase inhibitor letrozole on uterine leiomyomas and on bone metabolism. A prospective, open clinical trial was conducted in a university-based hospital. Sixteen premenopausal women with symptomatic uterine leiomyomas were treated with letrozole 5 mg/day orally for 3 months. The main outcome measures of uterine and uterine leiomyoma sizes, serum FSH, LH, oestradiol concentrations, ovarian volumes and myoma-related symptoms were noted at baselines and once a month during treatment. Lumbar spine bone mineral density and biochemical markers of bone metabolism were studied at the beginning and at the end of 3 months. Letrozole significantly decreased uterine leiomyoma sizes (P < 0.01) and promptly benefited women with heavy menstrual bleeding associated with leiomyomas without changing bone mineral density. Aromatase inhibitors may represent a new generation of medications for the treatment of leiomyoma and associated symptoms. Larger clinical trials are needed, however, to fully evaluate their safety and efficacy.


Journal of Minimally Invasive Gynecology | 2014

Trends in the National Distribution of Laparoscopic Hysterectomies From 2003 to 2010

Jinhyung Lee; Kristofer Jennings; Mostafa A. Borahay; Ana M. Rodriguez; Gokhan S. Kilic; Russell R. Snyder; Pooja R. Patel

STUDY OBJECTIVE The purpose of this analysis was to compare the trends in undergoing laparoscopic hysterectomy (versus abdominal or vaginal hysterectomy) based on patient age, race, median income and insurance type, from 2003 to 2010. DESIGN Retrospective study (Canadian Task Force classification II-3). SETTING National sample of hospital admissions after hysterectomy. PATIENTS Health Cost and Utilization Project-Nationwide Inpatient Sample database was used to review records of women who underwent hysterectomy for either menorrhagia or leiomyoma from 2003-2010. INTERVENTION The predicted probability of undergoing laparoscopic hysterectomy was determined for each year according to patient age, race, median income, and insurance type. The slopes of these values (i.e. the trend) was compared for each subgroup (i.e. black, white, Asian, etc.) in these categories. MAIN RESULTS A total of 530, 154 cases were included in this study. Total number of hysterectomies decreased by 39% from 60,364 to 36,835 from 2003 to 2010. The percent of hysterectomies that were laparoscopic increased from 11% in 2003 to 29% in 2010. All groups analyzed experienced an increase in predicted probability of undergoing a laparoscopic hysterectomy. Of all women undergoing hysterectomy, the probability of undergoing a laparoscopic hysterectomy remained highest for women who were less than 35 years old, white, with the highest median income, and with private insurance from 2003-2010. The slope was significantly greater for (1) white females versus all other races analyzed (p<0.01), (2) females in the highest income quartile versus females in the lowest income quartile (p<0.01) and (3) females with private insurance versus females with Medicaid (p<0.01) or Medicare (p<0.01). CONCLUSIONS There remains a gap in distribution of laparoscopic hysterectomies with regards to age, race, median income and insurance type that does not seem to be closing, despite the increased availability of laparoscopic hysterectomies.


PLOS ONE | 2009

Catechol-O-Methyltransferase Expression and 2- Methoxyestradiol Affect Microtubule Dynamics and Modify Steroid Receptor Signaling in Leiomyoma Cells

Salama A. Salama; Marwa W. Kamel; Shaleen Botting; Sana M. Salih; Mostafa A. Borahay; Ahmed A. Hamed; Gokhan S. Kilic; Muhammad Saeed; Marian Y. Williams; Concepcion Diaz-Arrastia

Context Development of optimal medicinal treatments of uterine leiomyomas represents a significant challenge. 2-Methoxyestradiol (2ME) is an endogenous estrogen metabolite formed by sequential action of CYP450s and catechol-O-methyltransferase (COMT). Our previous study demonstrated that 2ME is a potent antiproliferative, proapoptotic, antiangiogenic, and collagen synthesis inhibitor in human leiomyomas cells (huLM). Objectives Our objectives were to investigate whether COMT expression, by the virtue of 2ME formation, affects the growth of huLM, and to explore the cellular and molecular mechanisms whereby COMT expression or treatment with 2ME affect these cells. Results Our data demonstrated that E2-induced proliferation was less pronounced in cells over-expressing COMT or treated with 2ME (500 nM). This effect on cell proliferation was associated with microtubules stabilization and diminution of estrogen receptor α (ERα) and progesterone receptor (PR) transcriptional activities, due to shifts in their subcellular localization and sequestration in the cytoplasm. In addition, COMT over expression or treatment with 2ME reduced the expression of hypoxia-inducible factor -1α (HIF-1 α) and the basal level as well as TNF-α-induced aromatase (CYP19) expression. Conclusions COMT over expression or treatment with 2ME stabilize microtubules, ameliorates E2-induced proliferation, inhibits ERα and PR signaling, and reduces HIF-1 α and CYP19 expression in human uterine leiomyoma cells. Thus, microtubules are a candidate target for treatment of uterine leiomyomas. In addition, the naturally occurring microtubule-targeting agent 2ME represents a potential new therapeutic for uterine leiomyomas.


Molecular Medicine | 2015

Signaling Pathways in Leiomyoma: Understanding Pathobiology and Implications for Therapy.

Mostafa A. Borahay; Ayman Al Hendy; Gokhan S. Kilic; Darren Boehning

Uterine leiomyomas are the most common tumors of the female genital tract, affecting 50% to 70% of females by the age of 50. Despite their prevalence and enormous medical and economic impact, no effective medical treatment is currently available. This is, in part, due to the poor understanding of their underlying pathobiology. Although they are thought to start as a clonal proliferation of a single myometrial smooth muscle cell, these early cytogenetic alterations are considered insufficient for tumor development and additional complex signaling pathway alterations are crucial. These include steroids, growth factors, transforming growth factor-beta (TGF-β)/Smad; wingless-type (Wnt)/β-catenin, retinoic acid, vitamin D, and peroxisome proliferator-activated receptor γ (PPARγ). An important finding is that several of these pathways converge in a summative way. For example, mitogen-activated protein kinase (MAPK) and Akt pathways seem to act as signal integrators, incorporating input from several signaling pathways, including growth factors, estrogen and vitamin D. This underlines the multifactorial origin and complex nature of these tumors. In this review, we aim to dissect these pathways and discuss their interconnections, aberrations and role in leiomyoma pathobiology. We also aim to identify potential targets for development of novel therapeutics.


Obstetrics and Gynecology International | 2011

Comparison of Perioperative Outcomes of Total Laparoscopic and Robotically Assisted Hysterectomy for Benign Pathology during Introduction of a Robotic Program

Gokhan S. Kilic; Gradie Moore; Ayman Elbatanony; Carmen Radecki; John Y. Phelps; Mostafa A. Borahay

Study Objective. Prospectively compare outcomes of robotically assisted and laparoscopic hysterectomy in the process of implementing a new robotic program. Design. Prospectively comparative observational nonrandomized study. Design Classification. II-1. Setting. Tertiary caregiver university hospital. Patients. Data collected consecutively 24 months, 34 patients underwent laparoscopic hysterectomy, 25 patients underwent robotic hysterectomy, and 11 patients underwent vaginal hysterectomy at our institution. Interventions. Outcomes of robotically assisted, laparoscopic, and vaginal complex hysterectomies performed by a single surgeon for noncancerous indications. Measurements and Main Results. Operative times were 208.3 ± 59.01 minutes for laparoscopic, 286.2 ± 82.87 minutes for robotic, and 163.5 ± 61.89 minutes for vaginal (P < .0001). Estimated blood loss for patients undergoing laparoscopic surgery was 242.7 ± 211.37 cc, 137.4 ± 107.50 cc for robotic surgery, and 243.2 ± 127.52 cc for vaginal surgery (P = 0.05). The mean length of stay ranged from 1.8 to 2.3 days for the 3 methods. Association was significant for uterine weight (P = 0.0043) among surgery methods. Conclusion. Robotically assisted hysterectomy is feasible with low morbidity, a shorter hospital stay, and less blood loss. This suggests that robotic assistance facilitates a minimally invasive approach for patients with larger uterine size even during implementing a new robotic program.


Cancer Epidemiology, Biomarkers & Prevention | 2005

Loss of FHIT expression in breast cancer is correlated with poor prognostic markers

Banu Arun; Gokhan S. Kilic; Charles Yen; Barbara Foster; Denise A. Yardley; Richard B. Gaynor; Raheela Ashfaq

Objective: The fragile histidine triad (FHIT) gene is a putative tumor suppressor gene that is thought to be involved in the carcinogenesis of breast cancer. Loss of FHIT expression has been observed in up to 72% of breast cancers and has been associated with increased p53, a high proliferation index, and increased tumor size and grade. However, loss of FHIT expression has not been investigated in association with apoptosis and cyclooxygenase-2 (COX-2) expression in breast cancer. Furthermore, expression of FHIT in primary breast tumors and their metastatic axillary lymph nodes has also not been previously described. The purpose of this study was to evaluate the expression of FHIT, COX-2, bcl-2, and p53 in primary breast tumor tissue; correlate their expression with known clinical and pathologic markers; and in cases when tissue was available, evaluate the expression of FHIT and COX-2 in the corresponding metastatic axillary lymph node in the same patient. Methods: Primary breast tumor specimens from 80 patients were examined for the presence of FHIT, COX-2, bcl-2, and p53 expression by immunohistochemistry using standard methods. When tissue was available, the expression of FHIT and COX-2 was also evaluated in the corresponding metastatic axillary lymph node specimen. Results: FHIT expression in primary breast tumors was 56%. There was a significant correlation between FHIT expression in primary breast tumor and bcl-2 expression (P = 0.017). We also observed a significant inverse correlation between FHIT expression in primary breast tumor tissue and p53 expression (P = 0.023) in lymph node–negative cases. A significant inverse correlation between FHIT expression in the primary tumor and Ki-67 (P = 0.009) was also observed in lymph node–negative cases. FHIT expression in primary tumors correlated with FHIT expression in the metastatic lymph node (52.5%; P = 0.001). FHIT expression in primary tumors did not correlate with COX-2 expression. Conclusion: Our results suggest that loss of FHIT expression in breast cancer is associated with poor prognostic features. Furthermore, loss of FHIT expression is also seen in metastatic axillary lymph node. The prognostic and predictive value of these findings needs to be further evaluated in larger trials with longer follow-up.


Journal of Biological Chemistry | 2014

Simvastatin Potently Induces Calcium-dependent Apoptosis of Human Leiomyoma Cells

Mostafa A. Borahay; Gokhan S. Kilic; Chandrasekha Yallampalli; Russell R. Snyder; Gary D.V. Hankins; Ayman Al-Hendy; Darren Boehning

Background: Statins have broad-reaching effects beyond lowering plasma lipids, including antitumor properties. Results: Simvastatin inhibits proliferation and induces calcium-dependent apoptosis of human uterine leiomyoma cells. Conclusion: We report a novel calcium-mediated pathway associated with antitumor properties of simvastatin. Significance: Simvastatin may have antitumor properties significant for the treatment of human uterine leiomyomas. Statins are drugs commonly used for the treatment of high plasma cholesterol levels. Beyond these well known lipid-lowering properties, they possess broad-reaching effects in vivo, including antitumor effects. Statins inhibit the growth of multiple tumors. However, the mechanisms remain incompletely understood. Here we show that simvastatin inhibits the proliferation of human leiomyoma cells. This was associated with decreased mitogen-activated protein kinase signaling and multiple changes in cell cycle progression. Simvastatin potently stimulated leiomyoma cell apoptosis in a manner mechanistically dependent upon apoptotic calcium release from voltage-gated calcium channels. Therefore, simvastatin possesses antitumor effects that are dependent upon the apoptotic calcium release machinery.


Journal of Perinatal Medicine | 2014

Balloon tamponade for the management of postpartum uterine hemorrhage

Baris Kaya; Abdullah Tuten; Korkut Daglar; Mesut Mısırlıoğlu; Mesut Polat; Yusuf Yildirim; Orhan Unal; Gokhan S. Kilic; Onur Guralp

Abstract Objective: To evaluate the use of the Bakri balloon in postpartum hemorrhage (PPH) resistant to medical treatment. Methods: The Bakri balloon was applied to 45 women with PPH after failure of initial management. Bilateral internal iliac artery ligation (BIIAL) and hysterectomy were performed if necessary. Results: The Bakri balloon was applied in 45 women; an additional BIIAL was required in nine women. The mean inflation volume of the Bakri balloon was 571±264 mL (range: 240–1300 mL). Hemostasis was achieved in 34 (75.5%) women with the Bakri balloon alone, and in six women with an additional BIIAL. The Bakri balloon was effective with additional procedures overall in 40 of 45 (88.8%) women. In 34 women with uterine atony, the Bakri balloon was successful alone in 27 (79.4%) and with an additional BIIAL in 30 (88.2%) women. An inflation volume of >500 mL was necessary in 18 women with uterine atony. Conclusion: The Bakri balloon may be performed as a first line of treatment for PPH resistant to uterotonic agents, and can be used not only in tertiary centers but also in limited-resource centers. The inflation volume of the Bakri balloon should be adjusted according to the type of PPH; a volume exceeding 500 mL may be necessary in uterine atony.

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Mostafa A. Borahay

University of Texas Medical Branch

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Ana M. Rodriguez

University of Texas Medical Branch

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Omer Lutfi Tapisiz

University of Texas Medical Branch

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Pooja R. Patel

University of Texas Medical Branch

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Burak Zeybek

University of Texas Medical Branch

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Darren Boehning

University of Texas Health Science Center at Houston

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Salama A. Salama

Baylor College of Medicine

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Teresa M. Walsh

University of Texas Medical Branch

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