Investigation of telomerase activity and gene expression in colorectal cancer

İzgi, Ahu
Human telomerase is a reverse transcriptase which synthesizes telomeric repeat sequences at the ends of chromosomes. The telomerase enzyme has two essential subunits to be functional which are called telomerase reverse transcriptase (hTERT) and human telomerase RNA (hTR). Telomerase uses its RNA subunit as a template for the addition of hexameric repeats at the ends of chromosomes. The activity of telomerase has been detected in immortal cells but not in most normal somatic cells. Therefore, its activity could serve as diagnostic or prognostic marker in malignancies. Telomeres are heterochromatic DNA sequences bound by a number of telomere binding proteins in order to maintain the stability of chromosomes. Protection of telomere 1(POT1) is a single stranded telomere binding protein which is thought to have significant role in the recruitment of telomerase to telomeres. The objective of the current study to investigate telomerase activity and gene expression of hTERT and hPOT1 in human colorectal cancer tissues. The activity of telomerase was examined in colorectal tumors and normal adjacent specimens by and improved telomeric repeat amplification protocol (TRAP)-Silver Staining Assay. The expression levels of hTERT and hPOT1 genes was analysed by qPCR. The results showed that colorectal cancer tumors showed significantly high telomerase activity whereas normal adjacent tissues were found to be telomerase negative. Among clinicopathological parameters; the stage, histological type, distant metastasis and lymph node metastasis status of tumors were found to show significant differences in terms of telomerase activity. Moreover, the expression of human telomerase reverse transcriptase (hTERT) was found to be overexpressed in tumor tissues compared to normal adjacent tissues. Likewise, colorectal tumors expressed high level of hPOT1 compared to normal tissues. Both the expression of hTERT and hPOT1 correlated with telomerase activity. It can be concluded from the results of the current study that high telomerase activity and overexpression of hTERT and hPOT1, may indicate that they could serve as diagnostic or prognostic indicators in colorectal cancer.


Investigation of SNX3 in colon cancer
Cingöz, Harun; Erson Bensan, Ayşe Elif; Department of Biology (2019)
Sorting Nexin 3 (SNX3) is part of the retromer complex that recycles cargo receptors back to plasma membrane or to Trans Golgi Network. WNT ligand carrier protein Wntless (WLS) is a known SNX3 cargo protein. Our earlier data suggested over expression of SNX3 in colon cancer cells. Considering its importance in receptor recycling, we hypothesized SNX3 to be a potential modulator of cancer related receptors. To begin understanding the role of SNX3, we developed RNAi models of SNX3 in SW480 colon cancer cells ...
Investigation of telomerase activity in diagnosis of endometrial and cervical cancer
Eskiocak, Uğur; Gündüz, Ufuk; Department of Biology (2007)
Human telomerase is a ribonucleoprotein complex that adds hexameric TTAGGG repeats to the ends of chromosomes in order to prevent their shortening. Telomerase activity has been evaluated for its diagnostic and prognostic value in cancer since it is observed in most malignancies but not in most normal somatic tissues. In this study telomerase activity was examined in tumor specimens obtained from cervix, endometrium and their non-cancerous regions by an improved telomeric repeat amplification protocol (TRAP)...
Investigation of the therapeutic effect of sodium butyrate in Caco-2 colon cancer cell line by using ATR-FTIR spectroscopy
Çelik, Buket; Bek, Alpan; Özek, Nihal Şimşek; Department of Micro and Nanotechnology (2018)
Sodium butyrate (NaBt), as one of the HDACi, has been demonstrated that it induces apoptosis, cell cycle arrest, the inhibition of angiogenesis, metastasis and gene expression changes. To date, there are several studies perfomed to investigate its therapeutic effect; however, theexact mechanism at molecular level is not clear yet. Therefore, the current thesis was aimed to clarify the action/theurapeutic potential mechanisms of sodium butyrate in Caco2 colon cancer cell line at molecular level using ATR-FTI...
Application of copulas in graphical models for inference of biological systems
Dokuzoğlu, Damla; Purutçuoğlu Gazi, Vilda; Department of Statistics (2016)
Naturally, genes interact with each other by forming a complicated network and the relationship between groups of genes can be showed by different functions as gene networks. Recently, there has been a growing concern in uncovering these complex structures from gene expression data by modeling them mathematically. The Gaussian graphical model (GGM) is one of the very popular parametric approaches for modelling the underlying types of biochemical systems. In this study, we evaluate the performance of this pr...
Applications of terahertz spectroscopy in biosystems
Plusquellic, David F.; SİEGRİST, Karen; Heilweil, Edwin J.; Esentürk, Okan (Wiley, 2007-12-03)
Terahertz (THz) spectroscopic investigations of condensed-phase biological samples are reviewed ranging from the simple crystalline forms of amino acids, carbohydrates and polypeptides to the more complex aqueous forms of small proteins, DNA and RNA. Vibrationally resolved studies of crystalline samples have revealed the exquisite sensitivity of THz modes to crystalline order, temperature, conformational form, peptide sequence and local solvate environment and have given unprecedented measures of the bindin...
Citation Formats
A. İzgi, “Investigation of telomerase activity and gene expression in colorectal cancer,” M.S. - Master of Science, Middle East Technical University, 2012.