Nihal Karakaş

Dr. Nihal Karakaş


Research Focus & Metrics

Academic Career Length

8Years (2019-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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1 January 2019 in Medeniyet Medical Journal
Verified
Journal Article
Open access
NKNihal Karakaş
Nihal Karakaş
MOMehmet Evren Okur
Mehmet Evren Okur
IOIrem Ozturk
Irem Ozturk
SASule Ayla
Sule Ayla
AKAyşe Esra Karadağ
Ayşe Esra Karadağ
DPDerya Cicek Polat
Derya Cicek Polat
Blackthorn (Prunus spinosa L. (Rosaceae) is a shrup whose fruits are consumed as food in Turkey. This study was aimed to evaluate antioxidant activity of methanol extract of P. spinosa and its cytotoxic effects on cancer cell lines. Methanol extract of P. spinosa fruit was evaluated for its in vitro cytotoxic activity on multiform (GBM) brain cancer (LN229, U87 and T98G) and pancreas cancer (PANC-1 and AsPC-1) cell lines. Cell viability assays were performed by calculating the percentage of viable cells using a luminescence system, and spectrophotometrically. measuring its antioxidant ABTS and DPPH radical scavenging activities. Differences were considered as statistically significant at p*<0.001 and p**<0.0005 according to unpaired student t-test. Methanol extract of P. spinosa fruit showed 2548±18 mg GAE/100 g correspon-ding to the total phenolic content, and moderate antioxidant activity (0.1896±0.1143 and 0.0729±0.0348) by ABTS� and DPPH� assays. To the best of our knowledge, after evaluating the results of brain and pancreas cancer cell lines, significant cytotoxic activities with 50-63% cell viability of GBM brain cancer cells were determined while no cytotoxicity was observed on pancreas cancer cell lines, PANC-1; and AsPC-1. The results of this study showed that the methanol extract of P. spinosa fruit has significant antioxidant capacity and leads to statistically significant decreased viability on glioblastoma brain cancer cells.

1 March 2025 in American Journal of Physiology-Cell Physiology
Verified
Journal Article
Open access
SESümeyra Mengüç Emir
Sümeyra Mengüç Emir
BKBirnur Sinem Karaoğlan
Birnur Sinem Karaoğlan
RKRamazan Kaşmer
Ramazan Kaşmer
HŞHilal Buse Şirin
Hilal Buse Şirin
BSBatuhan Sarıyıldız
Batuhan Sarıyıldız
NKNihal Karakaş
Nihal Karakaş
Glioblastoma (GBM) remains one of the most aggressive and treatment-resistant brain malignancies in adults. Standard approaches, including surgical resection followed by adjuvant radio- and chemotherapy with temozolomide (TMZ), provide only transient control, as GBM frequently recurs due to its infiltrative nature and the presence of therapy-resistant subpopulations such as glioma stem cells (GSCs). GSCs, with their quiescent state and robust resistance mechanisms, evade conventional therapies, contributing significantly to relapse. Consequently, current treatment methods for GBM face significant limitations in effectively targeting GSCs. In this review, we emphasize the relationship between GBM recurrence and GSCs, discuss the current limitations, and provide future perspectives to overwhelm the challenges associated with targeting GSCs. Eliminating GSCs may suppress recurrence, achieve durable responses, and improve therapeutic outcomes for patients with GBM.

14 May 2020 in PLOS ONE
Verified
Journal Article
Open access
PDF file
NKNihal Karakaş
Nihal Karakaş
SBSadik Bay
Sadik Bay
NTNezaket Türkel
Nezaket Türkel
NÖNurşah Öztunç
Nurşah Öztunç
MÖMerve Öncül
Merve Öncül
GÖGürkan Öztürk
Gürkan Öztürk
Mesenchymal stem cells have the ability to transdifferentiate into neurons and therefore one of the potential adult stem cell source for neuronal tissue regeneration applications and understanding neurodevelopmental processes. In many studies on human mesenchymal stem cell (hMSC) derived neurons, success in neuronal differentiation was limited to neuronal protein expressions which is not statisfactory in terms of neuronal activity. Established neuronal networks seen in culture have to be investigated in terms of synaptic signal transmission ability to develop a culture model for human neurons and further studying the mechanism of neuronal differentiation and neurological pathologies. Accordingly, in this study, we analysed the functionality of bone marrow hMSCs differentiated into neurons by a single step cytokine-based induction protocol. Neurons from both primary hMSCs and hMSC cell line displayed spontaneous activity (≥75%) as demonstrated by Ca++ imaging. Furthermore, when electrically stimulated, hMSC derived neurons (hMd-Neurons) matched the response of a typical neuron in the process of maturation. Our results reveal that a combination of neuronal inducers enhance differentiation capacity of bone marrow hMSCs into high yielding functional neurons with spontaneous activity and mature into electrophysiologically active state. Conceptually, we suggest these functional hMd-Neurons to be used as a tool for disease modelling of neuropathologies and neuronal differentiation studies.

23 May 2022 in Frontiers in Pharmacology
Verified
Journal Article
Open access
DUDamla Uludağ
Damla Uludağ
SBSadık Bay
Sadık Bay
BSBilgesu Onur Sucu
Bilgesu Onur Sucu
ÖIÖzgecan Şavluğ İpEk
Özgecan Şavluğ İpEk
TMThomas Mohr
Thomas Mohr
NKNihal Karakaş
Nihal Karakaş
Change in the energy metabolism of cancer cells, which display significant differences compared to normal cells, is a rising phenomenon in developing new therapeutic approaches against cancers. One of the metabolic enzymes, hexokinase-II (HK-II) is involved in glycolysis, and inhibiting the HK-II activity may be a potential metabolic target for cancer therapy as most of the drugs in clinical use act on DNA damage. Methyl jasmonate (MJ) is one of the compounds blocking HK-II activity in cancer cells. In a previous study, we showed that the novel MJ analogs inhibit HK-II activity through VDAC detachment from the mitochondria. In this study, to evaluate the potential of targeting HK-2 activity, through patient cohort analysis, we first determined HK-2 expression levels and prognostic significance in highly lethal glioblastoma (GBM) brain tumor. We then examined the in vitro therapeutic effects of the novel analogs in the GBM cells. Here, we report that, among all, compound-10 (C-10) showed significant in vitro therapeutic efficacy as compared to MJ which is in use for preclinical and clinical studies. Afterward, we analyzed cell death triggered by C-10 in two different GBM cell lines. We found that C-10 treatment increased the apoptotic/necrotic cells and autophagy in GBM cells. The newly developed analog, C-10, was found to be lethal against GBM by the activation of cell death authorities, mostly in a necrotic and autophagic fashion at the early stages of the treatment. Considering that possibly decreased intracellular ATP levels by C-10 mediated inhibition of HK-2 activity and disabled VDAC interaction, a more detailed analysis of HK-2 inhibition–mediated cell death can provide a deep understanding of the mechanism of action on the oncosis/necroptosis axis. These findings provide an option to design clinically relevant and effective novel HK-II inhibitors and suggest novel MJ analogs to further study them as potential anticancer agents against GBM.

2 December 2022 in eLife
Verified
Journal Article
Open access
MIMetehan Ilter
Metehan Ilter
RKRamazan Kasmer
Ramazan Kasmer
FJFarzaneh Jalalypour
Farzaneh Jalalypour
CACanan Atilgan
Canan Atilgan
OTOzan Topcu
Ozan Topcu
OSOzge Sensoy
Ozge Sensoy
Undruggability of RAS proteins has necessitated alternative strategies for the development of effective inhibitors. In this respect, phosphorylation has recently come into prominence as this reversible post-translational modification attenuates sensitivity of RAS towards RAF. As such, in this study, we set out to unveil the impact of phosphorylation on dynamics of HRASWT and aim to invoke similar behavior in HRASG12D mutant by means of small therapeutic molecules. To this end, we performed molecular dynamics (MD) simulations using phosphorylated HRAS and showed that phosphorylation of Y32 distorted Switch I, hence the RAS/RAF interface. Consequently, we targeted Switch I in HRASG12D by means of approved therapeutic molecules and showed that the ligands enabled detachment of Switch I from the nucleotide-binding pocket. Moreover, we demonstrated that displacement of Switch I from the nucleotide-binding pocket was energetically more favorable in the presence of the ligand. Importantly, we verified computational findings in vitro where HRASG12D/RAF interaction was prevented by the ligand in HEK293T cells that expressed HRASG12D mutant protein. Therefore, these findings suggest that targeting Switch I, hence making Y32 accessible might open up new avenues in future drug discovery strategies that target mutant RAS proteins.

29 January 2022 in Cells
Verified
Journal Article
Open access
PDF file
NKNihal Karakaş
Nihal Karakaş
SÜSüleyman Üçüncüoğlu
Süleyman Üçüncüoğlu
DUDamla ULUDAĞ
Damla ULUDAĞ
BKBirnur Sinem Karaoğlan
Birnur Sinem Karaoğlan
KSKhalid Shah
Khalid Shah
GOGurkan Ozturk
Gurkan Ozturk
The novel pathogenic severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes coronavirus disease 2019 (COVID-19). Mesenchymal stem cells (MSCs) are currently utilized in clinics for pulmonary inflammatory diseases, including acute respiratory distress syndrome and acute lung injury. Given that MSCs offer a promising treatment against COVID-19, they are being used against COVID-19 in more than 70 clinical trials with promising findings. Genetically engineered MSCs offer promising therapeutic options in pulmonary diseases. However, their potential has not been explored yet. In this review, we provide perspectives on the functionally modified MSCs that can be developed and harnessed for COVID-19 therapy. Options to manage the SARS-CoV-2 infection and its variants using various bioengineering tools to increase the therapeutic efficacy of MSCs are highlighted.