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Richard Bach

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Interaction of E6 Gene from Human Papilloma Virus 16 (HPV-16) with CdS Quantum Dots

Transforming viruses can change a normal cell into a cancer cell during their standard life cycle. Persistent infections with these viruses have been recognized to cause some types of cancer [1].

Human papillomaviruses (HPVs) are small circular, double-stranded DNA viruses infecting epithelial tissues [2]. 150 HPV types have been discovered so far. These are classified into several genera based on their DNA sequence. HPV types can be classified both as high-risk and low-risk [3]. Cervical carcinoma represents the paradigm of virus-induced cancers, where all cervical cancers come from previous "high-risk" HPV infection [4]. The principal agent in the etiology of cervical cancer, i.e., human papillomavirus type 16 (HPV-16), encodes two oncoproteins as E6 and E7 [5]. These viral oncoproteins play important roles in regulation of viral functions during the viral life cycle and also contribute to the development of cancers [6]. In addition, these two proteins appear to affect carcinogenesis by their inhibitory effects on protein p53 [7] and retinoblastoma proteins (Rb) [8]. At first E6 is bound to the cellular ubiquitination enzyme E6-AP and then the complex with p53 is formed and proteolytic degradation occurs. This could trigger cell cycle disruption, proliferation promotion, and apoptosis inhibition [9]. The E6 protein from high-risk HPV type contains two zinc-binding domains with two C-x-x-C motifs each, where “x” represents other aminocids [10]. Due to numerous unclear mechanisms, some methods enabling us to monitor changes in vivo are searched for.

The quantum dots (QDs) belong to the new tool for fluorescence imaging of biological tissues, cancer targeting and diagnostic purposes [11-13]. The functionalized surface of QDs could be coupled with various biomolecules as aromatic heterocyclic compounds (naphthyridine) [14], proteins (metallothionein) [15] and DNA probes [16, 17]. Especially the nucleic acid can serve as robust ligand for aqueous synthesis of semiconductor nanocrystals or quantum dots [18]. It was shown that amino acid-modified QDs could be used as useful siRNA carriers to effectively silence a target HPV E6 gene as well as fluorescence probes for intracellular imaging [19].

QDs could be also used for detection of HPV viral particles in the cervical swamp samples using the biological separation [20]. The binding of the QDs with dsDNA could be investigated by indirect electrochemical [21, 22] or spectrophotometric methods [22, 23]. This phenomenon shows that the addition of QDs into DNA solution, causes the ground state complex of DNA with QDs formation [21]. The aim of this study was the characterization of the interaction and formed complex of blue and yellow fluorescent CdS-QDs with the gene encoding the HPV-16 protein E6. For this purpose the chip electrophoresis, UV/Vis spectrophotometry, and differential pulse voltammetry was used.

Práce je spojená s projektem CEITEC CZ.1.05/1.1.00/02.0068.

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