Ultrasound as a mean for non-invasive selective skin cancer therapy

Skin cancer is a prevalent type of cancer which can be divided into two main types: (1) non-melanoma skin cancers, mainly Basal Cell Carcinoma (BCC) and Squamous Cell Carcinoma (SCC); and (2) malignant skin cancer- melanoma. In this study we propose a non-invasive method to treat skin cancer based on ultrasound (US) application as opposed to the current treatments.

Previous studies have shown that malignant cells are less rigid and easier to deform than benign cells due to the reduction in the amount of organized F-actin filaments, which causes a weaker cytoskeletal structure, hence may possess the ability to migrate more easily through surrounding tissues. Since ultrasound induces mechanical stress on cells and tissues, we hypothesize that there are ultrasound conditions that will cause selective death of cancer cells while not damaging benign cells, based on the differences in their biomechanical properties.

The effect of ultrasound on cells’ viability was conducted in vitro and in vivo using QSONICA US 20KHz (plate horn - 600W and 13 mm probe - 125W, respectively). In the in-vitro experiments, benign skin cells and SCC cell lines from different sources were seeded on a 12 well plate, and each plate was exposed to ultrasound at different intensities and durations. Viability tests using Presto-blue reagent were performed, 1h after US applications. It was found that the viability percentage of SCC subtypes cells were significant lower than those of benign cells.

In the in-vivo experiments, NOD SCID mice were injected with CAL33 cell line, and when tumor reached 9 mm of diameter, US was applied. After one week from the first US application, the effects of single and continues treatment (every other day, four times total) with US on tumor viability, were investigated. Continuous treatment induced local anti-tumor effect in the treated reign. To further characterize the effect of US on the tumor morphology and pathology, we conducted immunohistochemistry analysis, indicating the damaged of tumor cells in the treated area. In addition, to support our hypothesis, AFM measurements for SCC and benign cells Young`s modulus are being conducted.