Abstract:
BACKGROUND : Computer-based technology is becoming increasingly essential in biological research where drug
discovery programs start with the identification of suitable drug targets. 2-Methoxyestradiol (2ME2) is a 17β-estradiol
metabolite that induces apoptosis in various cancer cell lines including cervical cancer, breast cancer and multiple
myeloma. Owing to 2ME2’s poor in vivo bioavailability, our laboratory in silico-designed and subsequently synthesized
a novel 2ME2 analogue, 2-ethyl-3-O-sulphamoyl-estra-1,3,5(10),15-tetraen-17-ol (ESE-15-ol), using receptor- and
ligand molecular modeling. In this study, the biological effects of ESE-15-ol (180 nM) and its parent molecule, 2ME2
(1 μM), were assessed on morphology and apoptosis induction in cervical cancer cells.
RESULTS : Transmission electron microscopy, scanning electron microscopy and polarization-optical transmitted
light differential interference contrast (PlasDIC) images demonstrated morphological hallmarks of apoptosis including
apoptotic bodies, shrunken cells, vacuoles, reduced cell density and cell debris. Flow cytometry analysis showed
apoptosis induction by means of annexin V-FITC staining. Cell cycle analysis showed that ESE-15-ol exposure resulted
in a statistically significant increase in the G2M phase (72%) compared to 2ME2 (19%). Apoptosis induction was more
pronounced when cells were exposed to ESE-15-ol compared to 2ME2. Spectrophotometric analysis of caspase 8
activity demonstrated that 2ME2 and ESE-15-ol both induced caspase 8 activation by 2- and 1.7-fold respectively indicating
the induction of the apoptosis. However, ESE-15-ol exerted all of the above-mentioned effects at a much lower
pharmacological concentration (180 nM) compared to 2ME2 (1 μM physiological concentration).
CONCLUSION : Computer-based technology is essential in drug discovery and together with in vitro studies for the
evaluation of these in silico-designed compounds, drug development can be improved to be cost effective and
time consuming. This study evaluated the anticancer potential of ESE-15-ol, an in silico-designed compound in vitro.
Research demonstrated that ESE-15-ol exerts antiproliferative activity accompanied with apoptosis induction at a
nanomolar concentration compared to the micromolar range required by 2ME2. This study is the first study to demonstrate
the influence of ESE-15-ol on morphology, cell cycle progression and apoptosis induction in HeLa cells. In
silico-design by means of receptor- and ligand molecular modeling is thus effective in improving compound bioavailability
while preserving apoptotic activity in vitro.
