Browsing by Subject "Transgelin"

Now showing 1 - 3 of 3

Open Access
Evaluation of TAGLN as a diagnostic marker in breast cancer
(2018-08) Köseer, Ayşe Sedef
Silecing of tumor suppressor genes via CpG hypermethylation in promoter regions is one of the frequent events occurring in different types of cancers. These genes have the potential as a diagnostic or a prognostic biomarker. Liquid biopsy is a relatively less invasive technique that is used for early diagnosis, therapy response prediction, minimal residual disease detection and real-time monitoring of tumor progression. In this study, a 402 bp region (-286 bp to -80 bp for Section 1, -102 bp to +115 bp for Section 2) located in TAGLN promoter containing 22 CpGs was analyzed in breast cancer patients and healthy donors to evaluate the biomarker potential of TAGLN promoter methylation levels in breast cancer. TAGLN promoter region was significantly hypermethylated in breast cancer patients (77.3%) compared to healthy donors (68.2%). Among differentially methylated CpGs, 6 out of 22 were hypermethylated and one was hypomethylated in breast cancer patients. We also analyzed the relationship between TAGLN promoter methylation levels and the patient's clinicopathological parameters. Analyses revealed that TAGLN promoter is highly methylated in breast cancer patients over 50 years of age compared to the healthy donors in the same age group. TAGLN promoter methylation did not differ as related to various clinicopathological parameters of breast cancer patients. TAGLN promoter methylation levels diagnosed breast cancer patients with 74.45% specificity and 57.58% sensitivity. Additionally, independent of the age group breast cancer patients (131.6 ng) exhibited higher levels of total cfDNA compared to healthy donors (56.4 ng). Pre- and postmenopausal breast cancer patients possessed higher total cfDNA levels compared to pre- and postmenopausal healthy donors. Total cfDNA levels did not differ in various clinicopathological parameters of breast cancer patients; however, total cfDNA levels diagnosed breast cancer patients with 73.33% specificity and 56.72% sensitivity. In summary, breast cancer patient sera can be used to identify the tumor profile, and TAGLN promoter hypermethylation and total cfDNA levels could serve as a diagnostic biomarker in breast cancer.
Open Access
Functional analysis of transgelin in breast cancer
(2018-06) Değer, Nazlı
Transgelin (TAGLN) is an actin-binding protein. It is highly expressed in fibroblasts and smooth muscle cells. In smooth muscle cells, it takes part in processes including motility and differentiation and also it has a role in the formation of stress fibers. TAGLN gene has been found to be downregulated by promoter hypermethylation in breast and colon tissues and in these tissues, it acted as a tumor suppressor gene. However, in a study on nerve sheath tumors, TAGLN expression was found as upregulated via hypomethylation and in nerve sheath tumors, it acted as a proto-oncogene. To the best of our knowledge, the functional effect of TAGLN gene expression has not been studied in detail in breast carcinoma cell lines. The aim of this study was therefore to identify the functional role of TAGLN in breast cancer development. Hence, TAGLN gene expression was silenced or overexpressed and functional analysis was performed in selected breast cancer cell lines. Breast cancer cell lines were chosen according to their subtypes such as basal, HER2 positive or triple negative; their migratory properties; epithelial or mesenchymal characteristics and the expression level of TAGLN. Therefore, triple negative and mesenchymal MDA-MB-157 cells and MDA-MB-231 cells that express TAGLN at medium level were selected to silence TAGLN expression. The same cell lines and HER2 positive and epithelial MDA-MB-361 cells which express TAGLN at very low level were selected to overexpress TAGLN gene. Immunofluorescence and western blot analysis showed that in MDA-MB-157 and MDA-MB-231 cells mesenchymal marker Vimentin expression is correlated with TAGLN gene expression level. On the contrary, a reverse relationship exists in MDA-MB-361 cells where E-Cadherin expression increased and Vimentin expression decreased in TAGLN overexpressing MDA-MB-361 cells. TAGLN silencing in MDA-MB-157 cells increased the cell spreading potential and viability capacity while TAGLN upregulated cells did not show any significant change. TAGLN silencing in MDA-MB-231 cells decreased the cell spreading potential and cell viability of the cells, TAGLN overexpression in MDA-MB-231 cells increased these properties of cells. MDA-MB-361 cells behaved differently with TAGLN overexpression; cells were able to form less colonies and cell viability decreased in TAGLN overexpressing cells. TAGLN gene silencing affected the cell cycles of MDA-MB-157 and MDA-MB-231 cells but TAGLN overexpression had no effect on the cell cycle. In conclusion, TAGLN expression has an effect on Epithelial to Mesenchymal Transition (EMT) by altering the expression of established EMT markers E-Cadherin and Vimentin and its effect is based on the original morphology of the respective cell lines. In this study, the effect of TAGLN expression on cell proliferation was also studied and TAGLN seems to be acting as a tumor suppressor in MDA-MB-157 and MDA-MB-361 cells and as an oncogene in MDA-MB-231 cells. This might be due to the invasive character of MDA-MB-231 cells and the underlying mechanisms for this outcome should be investigated. Also, in vivo experiments can be performed to see whether changes in the expression of TAGLN gene has a role in tumor formation or metastasis capacity of cells.
Open Access
Unmasking of epigenetically silenced genes and identification of transgelin as a potential methylation biomarker in breast cancer
(2015-11) Sayar, Nilüfer
Tumor suppressor genes (TSG) are frequently silenced in cancer by epigenetic mechanisms, including promoter DNA hypermethylation and repressive chromatin formation by means of histone deacetylation. 5-aza-2'-deoxycytidine (AZA) and Trichostatin A (TSA) are DNA methyl-transferase and histone deacetylase inhibitors, respectively, and are used as anti-cancer agents for induction of epigenetically suppressed genes. In this study, in an attempt to unmask epigenetically suppressed potential TSGs in breast cancer, two breast carcinoma cells and one non-tumorigenic breast cell line were treated with AZA and TSA, either separately or in combination, and with DMSO as control. Afterwards, highthroughput expression profiling revealed significantly affected genes and pathways in response to epigenetic induction in each cell line. Analysis of 32 candidate genes highlighted Transgelin (TAGLN) as a putative TSG that is frequently downregulated by promoter DNA hypermethylation in breast cancer cell lines, and in 61.9% of normal-paired breast tumors according to bisulfite sequencing; and in 63.02% of unpaired breast tumor tissues as determined by bioinformatics analyses of public microarray data. Both relapse-free and overall survivals of patients were more favorable with lower TAGLN methylation. Moreover, TAGLN promoter methylation levels diagnosed tumors tissues with 83.14% sensitivity and 100% specificity. qRTPCR and IHC experiments demonstrated that, TAGLN was persistently downregulated in breast cancer cell lines in comparison to non-tumorigenic cells; and in three independent sets of breast tumor tissues, compared to normal tissues. Furthermore, TAGLN expression was associated with good prognostic factors. Functional analyses in breast cancer cells revealed negative effect of transgelin on colony formation abilities of cells, and analyses with epithelial-to-mesenchymal (EMT) markers implicate an association of transgelin with EMT status of breast cancer. In short, TAGLN downregulation by promoter DNA hypermethylation in breast cancer could serve as a growth advantage to the breast cancer cells, while it could be used as a diagnostic or prognostic biomarker for breast cancer.