High intensity focused ultrasound-induced bubbles stimulate the release of nucleic acid cancer biomarkers

Background/introduction Prostate biopsy for prostate cancer (PCa) is invasive with associated morbidity and several diagnostic limitations, suggesting the need for a new approach. Recently, several nucleic acid cancer biomarkers (e.g., microRNA and mutant DNA) have been identified and shown promise for improving cancer diagnostics. However, the abundance of these biomarker classes in the circulation is low, impeding reliable detection and adoption into clinical practice. In order to stimulate the release of these intracellular biomarkers, the exposures optimized for mechanical disruption of cells may be desirable. Here, two approaches based on HIFU-induced bubble activity were tested for their ability to stimulate release of cancer-associated microRNAs in a heterotopic syngeneic rat prostate cancer model. In the first approach, tumor tissue was locally liquefied with boiling histotripsy (BH) a HIFU technique utilizing millisecond-long pulses to create boiling bubbles via rapid shockwave heating. The interaction of shocks with the ensuing vapor cavity fractionates tissue with negligible thermal effect. In the second approach HIFU-induced inertial cavitation was used for permeabilization of tumor tissue and vasculature.