Sains Malaysiana 48(9)(2019): 1833–1840

http://dx.doi.org/10.17576/jsm-2019-4809-04

Investigation of Boldine as a Potential Telomerase Inhibitor by Downregulation of hTERT/hTERC in HCT 116 Human Colon Carcinoma Cells

(Kajian Boldina sebagai Perencat Telomerase Berpotensi oleh Pengawalaturan Rendah hTERT/hTERC dalam HCT 116 Karsinoma Sel Kolon Manusia)

NADHIRAH AHMAD, CHING JOO JIE & NAZIA ABDUL MAJID*

Institute of Biological Sciences, Faculty of Science, University of Malaya, 50603 Kuala Lumpur, Federal Territory, Malaysia

Diserahkan: 25 September 2018/Diterima: 24 Jun 2019

ABSTRACT

Telomerase, a ribonucleoprotein (RNP) complex, is a type of RNA-dependent DNA polymerase that synthesises telomeric DNA repeats (TTAGGG) at the 3’ end of chromosomes. Most of the cancer cells express high level of telomerase which results in cellular immortality. The high telomerase activity in cancer cells can be detected via expression of human TERT (hTERT), the catalytic protein subunit of telomerase, and expression of human TERC (hTERC), the RNA component in telomerase. Boldine, a natural alkaloid compound, was shown to have anticancer properties on various types of cancer cells, but the anti-telomerase property was poorly understood. This study was carried out to investigate the ability of boldine in targeting telomerase on the human colon cancer cell line, HCT 116, by analyzing the expression of hTERT and hTERC. Boldine was shown to have a time- and dose-dependent cytotoxic effect on HCT 116 cell line in SRB assay. The protein expression of hTERT was assessed through Western blot where it was observed to be down-regulated upon boldine treatment compared to control. The cells treated with boldine also exhibited a down-regulation of mRNA expression for both hTERT and hTERC in Real Time PCR (qRT-PCR). The down-regulation of hTERT protein expression correlated with the reduced hTERC mRNA expression in qRT-PCR. The observations on the down-regulation of protein and mRNA expressions of telomerase related genes, hTERT and hTERC, in this study suggested that boldine might become a significant candidate for telomerase-targeted anti-cancer therapy.

Keywords: Boldine; cancer; hTERC; hTERT; telomerase

ABSTRAK

Telomerase, iaitu satu kompleks ribonukleoprotein (RNP) merupakan sejenis DNA polimerase bersandar RNA yang mensintesis telomerik DNA berulangan (TTAGGG) pada hujung kromosom. Kebanyakan sel kanser mengekspres telomerase pada tahap yang tinggi dan akan mengakibatkan sel mencapai keabadian. Aktiviti telomerase yang tinggi dalam sel kanser dapat dikesan melalui pengekspresan TERT manusia (hTERT) iaitu subunit protein katalitik telomerase dan pengekspresan TERC manusia (hTERC) iaitu komponen RNA dalam telomerase. Boldina merupakan sebatian alkaloid semula jadi yang mempunyai sifat antikanser terhadap pelbagai jenis sel kanser, namun begitu sifat anti-telomerase masih kurang difahami. Kajian ini dijalankan untuk mengkaji keupayaan boldina untuk mensasarkan telomerase dalam titisan sel kanser kolon manusia, HCT 116 dengan menganalisis pengekspresan hTERT dan hTERC. Boldina dikatakan mempunyai kesan sitotoksik yang bersandar kepada masa and dos terhadap titisan sel HCT 116 dalam asai SRB. Pengekspresan protein hTERT telah dinilai melalui Western blot dengan pengawalaturannya menurun selepas rawatan dengan boldina berbanding kawalan. Sel yang dirawat dengan boldina juga menunjukkan pengawalaturan yang menurun bagi pengekspresan mRNA untuk kedua-dua hTERT dan hTERC melalui PCR masa sebenar (qRT-PCR). Pengawalaturan yang menurun bagi pengekspresan protein hTERT didapati berkorelasi dengan pengurangan pengekspresan mRNA hTERC melalui qRT-PCR. Pemerhatian terhadap pengawalaturan yang menurun bagi pengekspresan protein dan mRNA gen berkait telomerase, hTERT dan hTERC dalam kajian ini mencadangkan bahawa boldina berkemungkinan menjadi calon penting untuk terapi antikanser yang mensasarkan telomerase.

Kata kunci: Boldina; hTERC; hTERT; kanser; telomerase

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*Pengarang untuk surat-menyurat; email: nazia@um.edu.my