Development of xenograft model
All of the experimental procedures were permitted by the Institutional
Animal Ethics Committee of the Korea Institute of Science and Technology
(KIST), Korea. Fifteen male BALB/c nude mice aged 6 weeks weighing 23-27
g were purchased from Nara Controls Inc. (Seoul, Korea). The mice were
then housed for one week to acclimate to the ambient environment, and
during the acclimation period, the temperature (25 ± 2 °C), the humidity
(50-60%) and a 12 h light/dark cycle (8:00 am – 8:00 pm) were
maintained. The mice were initially divided into two groups: the normal
control group (NC; n=5) and the tumor xenograft group (n=10). After one
week, one million LS174T cells were subcutaneously injected into the
right flank of the nude mice for xenograft model development, and blank
media was injected into the normal control group following the same
xenograft model procedure. Once the tumor size reached approximately
150-200 mm3, the xenograft group was further divided
into two groups: a xenograft control group (XC; treated with vehicle,
n=5), and a PP242-treated group (treated with PP242; n=5). PP242
solution (formulated with 2% ethanol, 20% PEG400 and 1% Tween 80 in
distilled water) was administered orally to the xenograft mice at a dose
of 60 mg.kg-1.day-1 for 21
continuous days. The same volume of vehicle was orally administered to
the NC and XC group mice for the same duration. Measurements of tumor
volume in the right flank region and body weights were carried out in
two day intervals. The tumor size was measured using a digital caliper
and calculated with the formula:
\(Volume\ =\text{weight}^{2}\ \times\ \frac{\text{Length}}{2}\).
After 21 days of treatment, the mice were anaesthetized, and blood was
collected through cardiac puncture. Liver, kidney and tumor tissues were
collected and immediately snap frozen in liquid nitrogen. Plasma was
then obtained from the blood samples upon centrifugation. All the
samples were stored at -80 °C until further analysis.