Specific Aims (Revised 1-29-2024) For treating ovarian cancer, paclitaxel is the front-line drug used in combination with cisplatin/carboplatin, and is also used alone in a dose dense schedule for recurrent cancer. A highly effective anti-microtubule agent, paclitaxel also causes dose-limiting adverse effects. In particular, as many as 80% of patients receiving paclitaxel develop alopecia, which severely impacts patients’ quality of life. We have discovered that a brief exposure to low-intensity ultrasound can protect various types of proliferating cells from the cytotoxic activity of paclitaxel and cell death in vitro by transiently disrupting paclitaxel-induced formation of rigid and stabilized microtubule bundles. We hypothesize that, through this mechanism, low-intensity ultrasound may prevent alopecia (locally) without compromising the efficacy of systematic cancer therapy. The objectives of the proposal are to test the hypothesis, using human scalp hair follicle organ cultures and suitable mouse models. The initial basic experiments are supported by an DOD pilot funding, and the R01 support will further extend the goals and work, and solidify the results and conclusions, which will guide optimal design of a protocol for clinical trial in the near future. Specific Aim 1. Investigate mechanisms: breaking of the drug-stabilized microtubules and cellular mechanisms in countering paclitaxel activity. Sub-Aim 1-1: In cell-free system, we will investigate the fragmentation of polymerized microtubules by low intensity ultrasound, with and without the presence of paclitaxel. Sub-Aim 1-2: In human scalp hair follicle organ culture, we will study ultrasound impacts on microtubules: their breaking, aggregation of fragments, and degradation by autophagy and in lysosomes. Sub-Aim 1-3: In human scalp hair follicle organ culture, we will study the ultrasound rescuing of cells death by paclitaxel + carboplatin combination, which is commonly used in the treatment of ovarian cancer. Sub-Aim 1-4: We will also verify the ability of ultrasound to counter additional taxanes, including docetaxel and cabazitaxel, which are used in treatment of metastatic breast and prostate cancer, respectively. Sub-Aim 1-5: We will study a serious of time courses, from immediate (5 min), to long term (7 days) of the effects of paclitaxel and/or ultrasound in the human scalp hair follicle organ cultures. The hair follicle organ culture system will enable our intricate analyses using microscopy and cell biology approaches to interrogate both temporary and permanent paclitaxel-induced damage, and this aim will identify underlying protective mechanisms of ultrasound therapy. Specific Aim 2. Verify the prevention of hair follicle damage and study the mechanism of ultrasound in countering paclitaxel cytotoxicity in live mice. Sub-Aim 2-1: We will carry out extensive analyses to verify the biology and mechanisms in live mice. Sub-Aim 2-2: In human scalp hair follicle organ culture, we wi...