Figure 4.

Ultrasound exposure reverses cytotoxicity by disrupting rigid microtubule filaments induced by paclitaxel (Taxol) treatment of cells. Microtubule bundles radiate out from the microtubule organizing center. Ultrasound (US) is known to transiently disrupt microtubule networks, which reform within 1-2 hours. Paclitaxel (Taxol) induces rigid microtubule filaments that lead to growth arrest and subsequent cell death in proliferative cells such as cancer cells or matrix keratinocytes of the hair follicles. We suggest a mechanism through which ultrasound reverses cytotoxicity by disrupting rigid microtubule filaments induced by paclitaxel. The paclitaxel-bound microtubule fragments and tubulins are relocated to lysosomes for degradation, and newly synthesized tubulins form a new network of microtubule cytoskeleton without bound paclitaxel. Thus, a brief exposure to low intensity ultrasound removes cellular paclitaxel activity/cytotoxicity.