Treatment of multi-drug-resistant hepatoblastoma cells using unique sequence of high-intensity focused ultrasound and low-dose generic chemotherapeutic.

Abstract

e22008 Background: High-intensity focused ultrasound (HIFU) is a noninvasive, radiation-free, and precisely targeted form of cancer therapy. In this study, I evaluate a new strategy in which the unique sequence of HIFU and low-dose generic chemotherapeutic is utilized to kill multidrug-resistant (MDR) hepatoblastoma cells. Methods: My strategy, motivated by clinical HIFU trials in adult hepatocellular cancers, led to the in vitro study in which human hepatoblastoma cell line HepG2 (ATCC HB8065), known for resistance to 5-fluorouracil (5-FU), was paradoxically treated with low-dose 5-FU in the following sequence. Day 0: Each data sample consisted of ~10K HepG2 cells grown inside a well of 8-well glass slides (Lab-Tek). Each well was then filled with growth media and incubated at 37ºC for 24h. Day 1: Each slide was sealed, submerged in a 37ºC degassed water bath and secured onto a fixture. The targets for HIFU therapy are the center points of the 4 quadrants of each well's base and the common origin. The constant HIFU parameters for each slide were acoustic pressure 4.5 MPa, repetition rate 1 Hz, focal-zone depth and 30 sec/sonication/target while HIFU duty cycle (DC) ranged 0-50% among slides. After HIFU treatment, the slides were incubated for 24h. Day 2: Cell media for each slide was replaced with fresh media containing [5-FU] 0-400 uM prior to repeating HIFU procedure from day 1. Day 4: After 48h of exposure to 5-FU, cell survivability study using imaging-based live cell count was performed to determine the contributions of HIFU-mediated necrosis and 5-FU-mediated apoptosis/necrosis. Results: Cell survivability of MDR HepG2 cells decreased further using HIFU/5-FU sequence than with either HIFU or 5-FU alone as shown below (Table). Conclusions: The unique sequence of HIFU and low-dose 5-fluorouracil was successful in eliminating MDR hepatoblastoma cells on day 4. Treatment of HepG2 hepatoblastoma cells using HIFU/5-FU sequence. [5-FU], (uM) 0 1 10 100 200 400 95% CI of cell survivability (%) on day 4 = estimate ± margin of error;HIFU DC 0%, N=4 100± 12 81± 37 44± 13 30± 4 34± 5 39± 3 95% CI of cell survivability (%) on day 4 = estimate ± margin of error; HIFU DC 50%, N=4 30±5 7±1 10± 4 10± 2 11± 3 8±3