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In JoVE (1)
Other Publications (6)
Articles by Habibe Demir in JoVE
JoVE Clinical and Translational Medicine
Method for Novel Anti-Cancer Drug Development using Tumor Explants of Surgical Specimens
1Department of Neurological Surgery, The Ohio State University Medical Center, 2Department of Pathology, The Ohio State University Medical Center
Here, we established a method for drug efficacy testing with surgical specimens of brain tumors, termed “tumor explant method”. With this method, we can evaluate drug efficacy without breaking the microenvironment of solid tumors. To validate reliability of this method, we describe representative data with our glioma specimen treated with the current first-line chemotherapeutic agent, temozolomide.
Other articles by Habibe Demir on PubMed
Identification and Characterization of Human Embryonic Poly(A) Binding Protein (EPAB)
Transcriptional silencing that begins with oocyte maturation persists during the initial mitotic divisions of the embryo. Gene expression during this period largely depends on the translational activation of maternal mRNAs by cytoplasmic polyadenylation and requires an embryonic poly(A) binding protein (EPAB). EPAB has been identified in Xenopus and mouse, where it is expressed exclusively in oocytes and early embryos until zygotic genome activation (ZGA) when it is replaced by the somatic cytoplasmic poly(A) binding protein (PABPC1). EPAB plays a central role in the regulation of maternal mRNA activation by preventing deadenylation and promoting translation. In this study, we identified and characterized the human EPAB ortholog. Human EPAB is a 619 amino acid protein with 77% identity and 84% similarity to mouse EPAB. Human EPAB mRNA is detected in ovaries, testes and several somatic tissues including pancreas, liver and thymus. Similar to the observations in Xenopus and mouse, human EPAB is the predominant poly(A) binding protein in immature (germinal vesicle) and mature (metaphase II) oocytes, and it is replaced by PABPC1 following ZGA, which occurs at 4- to 8-cell stage in human. Our findings suggest that the unique translational regulatory pathways that control gene expression during oogenesis and early embryo development may be common between model organisms and humans.
Successful Medical Management of Post-hysteroscopic Metroplasty Bleeding with Intravenous Estrogen Therapy: a Report of Two Cases and Review of the Literature
Complications from hysteroscopy are rare, but some are potentially life-threatening. Hemorrhage is one of the most common complications of hysteroscopy. In this study, we report 2 cases of post-hysteroscopic bleeding successfully treated with intravenous conjugated equine estrogen (CEE). In our case report, 2 women who were evaluated for infertility were diagnosed with intrauterine septum. After surgical resection of the septum, significant late post-hysteroscopic bleeding was seen in the fourth and eighteenth day of surgery, respectively. Both patients were successfully treated with intravenous CEE 25mg in normal saline solution 50 mL given over 20 minutes every 6 hours. These 2 cases illustrate that intravenous CEE therapy as a short-term treatment is relatively safe and can be considered as an alternative in the treatment of severe post-hysteroscopy bleeding in selected patients without risk factors. In patients with risk factors, such as previous thromboembolic disease, alternative modalities of treatment should be considered.
Internal Herniation of Adnexa Through a Defect of the Broad Ligament: Case Report and Literature Review
Internal herniation through a defect of the broad ligament occurs rarely. Herniation of the ovary rather than the small intestine or colon is extremely rare. We present only the third known case of herniation of the adnexa into a broad ligament defect. A 42-year-old woman, gravida 3, para 2, aborta 1, had severe continuing right lower quadrant pain that was resistant to medical and surgical treatments. The clinical history was significant for long-standing endometriosis, 2 previous laparoscopic procedures to treat endometriosis, and chronic pelvic pain despite medical and surgical treatments. At the second laparoscopic procedure, pelvic endometriosis was excised, and a large defect of the right broad ligament was noted but not treated. At the third operation, right salpingo-oophorectomy was performed to eliminate the large broad ligament defect and the possibility of internal herniation on the right side as a possible explanation for the patient's chronic right lower quadrant pain. Postoperatively, the pain resolved, and the patient has been pain-free for 9 months. This type of internal herniation should be considered in the differential diagnosis in female patients with pelvic pain.
CD44v6 Regulates Growth of Brain Tumor Stem Cells Partially Through the AKT-mediated Pathway
Identification of stem cell-like brain tumor cells (brain tumor stem-like cells; BTSC) has gained substantial attention by scientists and physicians. However, the mechanism of tumor initiation and proliferation is still poorly understood. CD44 is a cell surface protein linked to tumorigenesis in various cancers. In particular, one of its variant isoforms, CD44v6, is associated with several cancer types. To date its expression and function in BTSC is yet to be identified. Here, we demonstrate the presence and function of the variant form 6 of CD44 (CD44v6) in BTSC of a subset of glioblastoma multiforme (GBM). Patients with CD44(high) GBM exhibited significantly poorer prognoses. Among various variant forms, CD44v6 was the only isoform that was detected in BTSC and its knockdown inhibited in vitro growth of BTSC from CD44(high) GBM but not from CD44(low) GBM. In contrast, this siRNA-mediated growth inhibition was not apparent in the matched GBM sample that does not possess stem-like properties. Stimulation with a CD44v6 ligand, osteopontin (OPN), increased expression of phosphorylated AKT in CD44(high) GBM, but not in CD44(low) GBM. Lastly, in a mouse spontaneous intracranial tumor model, CD44v6 was abundantly expressed by tumor precursors, in contrast to no detectable CD44v6 expression in normal neural precursors. Furthermore, overexpression of mouse CD44v6 or OPN, but not its dominant negative form, resulted in enhanced growth of the mouse tumor stem-like cells in vitro. Collectively, these data indicate that a subset of GBM expresses high CD44 in BTSC, and its growth may depend on CD44v6/AKT pathway.
Telomestatin Impairs Glioma Stem Cell Survival and Growth Through the Disruption of Telomeric G-quadruplex and Inhibition of the Proto-oncogene, C-Myb
PURPOSE: Glioma stem cells (GSCs) are a critical therapeutic target of glioblastoma multiforme (GBM). EXPERIMENTAL DESIGN: The effects of a G-quadruplex ligand, telomestatin (TMS), were evaluated using patient-derived GSCs, non-stem tumor cells (non-GSCs), and normal fetal neural precursors in vitro and in vivo. The molecular targets of TMS were determined by immunofluorescence in situ hybridization (iFISH) and cDNA microarray. The data was then validated by in vitro and in vivo functional assays, as well as by immunohistochemistry against 90 clinical samples.RESULTS: TMS impaired the maintenance of GSC stem cell-state by inducing apoptosis in vitro and in vivo. The migration potential of GSCs was also impaired by TMS treatment. In contrast, both normal neural precursors and non-GSCs were relatively resistant to TMS. Treatment of GSC-derived mouse intracranial tumors reduced tumor sizes in vivo without a noticeable cell death in normal brains. iFISH revealed both telomeric and non-telomeric DNA damage by TMS in GSCs but not in non-GSCs. cDNA microarray identified a proto-oncogene, c-Myb, as a novel molecular target of TMS in GSCs and pharmacodynamic analysis in TMS-treated tumor-bearing mouse brains demonstrated a reduction of c-Myb in tumors in vivo. Knockdown of c-Myb phenocopied TMS-treated GSCs both in vitro and in vivo, and restoring c-Myb by overexpression partially rescued the phenotype. Lastly, c-Myb expression was markedly elevated in surgical specimens of GBM compared to normal tissues. CONCLUSIONS: These data indicate that TMS potently eradicates GSCs through telomere disruption and c-Myb inhibition, and this study suggests a novel GSC-directed therapeutic strategy for GBM.
In Vitro Fertilization Pregnancy Rates in Levothyroxine-Treated Women with Hypothyroidism Compared to Women Without Thyroid Dysfunction Disorders
Background: Untreated hypothyroidism can lead to ovulatory dysfunction resulting in oligo-amenorrhea. Treatment with levothyroxine can reverse such dysfunction and thus should improve fertility. The purpose of this retrospective study was to assess whether in vitro fertilization (IVF) pregnancy rates differ in levothyroxine-treated women with hypothyroidism compared to women without thyroid dysfunction disorders. Methods: Treated hypothyroid and euthyroid women undergoing IVF at an academic IVF center were studied after Institutional Review Board approval. Women with hypothyroidism were treated with levothyroxine 0.025-0.15 mg/day for at least 3 months to maintain baseline thyrotropin (TSH) levels of 0.35-4.0 µU/ml prior to commencing IVF treatment (HYPO-Rx group). Causes of infertility were similar in both groups with the exception of male factor, which was more common in the HYPO-Rx group. The main outcomes studied were implantation rate, clinical pregnancy rate, clinical miscarriage rate, and live birth rate. Results: We reviewed the first IVF retrieval cycle performed on 240 women aged 37 years or less during the period January 2003 to December 2007. Women with treated hypothyroidism (n=21) had significantly decreased implantation, clinical pregnancy and live birth rates than euthyroid women (n=219). Conclusions: We conclude that, despite levothyroxine treatment, women with hypothyroidism have a significantly decreased chance of achieving a pregnancy following IVF compared to euthyroid patients. A larger prospective study is necessary to assess confounding variables, confirm these findings and determine the optimal level of TSH prior to and during controlled ovarian hyperstimulation for IVF.
