Skin Cancer Chemoprevention by Silibinin: Mechanisms and Efficacy

项目摘要摘要 基底细胞癌(BCC)是一种非黑色素瘤皮肤癌(NMSC)，是老年人的主要健康问题。 美国；仅BCC年度发病率就高于所有其他癌症发病率的总和(1.67 百万/年)。大多数基底细胞癌病例可以通过手术或放射治疗治愈，但这可能会带来痛苦和严重的毁容。 对于患有局部晚期和转移性疾病的基底细胞癌患者，不是可行的治疗选择 化疗也没有被证明是有效的。由于Hedgehog(HH)信号在BCC中起核心作用 发展和进展，最近FDA批准了GDC-0449和LDE-225(HH途径抑制剂)来 治疗基底细胞癌；然而，获得性耐药性和毒性是有限的。综上所述，显然有一个 迫切需要制定更多的无毒战略，以预防和干预基底细胞癌。 在过去的20年里，我们广泛地研究和报道了水飞蓟宾对紫外线的化学预防作用。 诱导皮肤鳞状细胞癌(SCC)模型的NMSC；目前，我们处于晚期 开发供人类皮肤使用的水飞蓟宾制剂。根据研究结果显示水飞蓟宾在 小鼠皮肤鳞状细胞癌模型，在初步研究中，我们还评价了其对UVB诱导的基底细胞癌的抑制作用。vbl.使用 Ptch1+/−小鼠BCC模型，观察水飞蓟宾对中波紫外线诱导的环丁烷嘧啶的影响 耳部皮肤中二聚体(CPD)阳性细胞、显微镜下基底细胞癌的形成、真皮肥大细胞的浸润和骨 皮肤中形态发生蛋白-2的基因和蛋白水平。此外，水飞蓟宾下降：MC9肥大 细胞向小鼠BCC Asz细胞的趋化迁移和粘膜肥大细胞脱颗粒。水飞蓟宾也 小鼠BCC细胞在培养和小鼠同种异体移植物中的增殖抑制及有丝分裂抑制 信号通路。在最近的研究中，水飞蓟宾显著增强了HH的生长抑制作用 并通过靶向EGFR/AKT和AKT逆转BCC细胞对这些药物的耐药性 HH途径与诱导细胞凋亡。基于BCC的这些非常重要和令人鼓舞的发现 模型中，我们的假设是通过靶向UVB诱导的DNA损伤修复和逆转肥大 细胞介导的免疫抑制事件及其相关的调控信号通路 由于具有耐药性，水飞蓟宾有可能成为预防和治疗 基底细胞癌的辅助治疗。我们的目标是：i)建立和确定水飞蓟宾介导的DNA修复在 它对UVB诱导的基底细胞癌的预防作用；II)评估和建立DNA损伤之间的联系 水飞蓟宾对中波紫外线诱导的免疫抑制的修复、肥大细胞和逆转作用 形成；三)进一步确定水飞蓟宾单独和联合治疗基底细胞癌的疗效 与FDA批准的抗基底细胞癌治疗药物，并定义相关的机制。

Project Summary Abstract Basal cell carcinoma (BCC), a non-melanoma skin cancer (NMSC) type, is a major health problem in the United States (US); annual BCC incidences alone are higher than all other cancer incidences combined (1.67 million/year). Most BCC cases are curable by surgery/radiation, but these can be painful and highly disfiguring and are not viable treatment options for BCC patients with locally advanced and metastatic disease where chemotherapy has also not proven effective. Since Hedgehog (Hh) signaling plays a central role in BCC development and progression, recently FDA has approved GDC-0449 and LDE-225 (Hh pathway inhibitors) to treat BCC; however, acquired resistance and toxicities are limitations. Taken together, clearly there is an urgent need to develop additional non-toxic strategies towards BCC prevention and intervention. In past ~20 years, we have extensively studied and reported chemopreventive efficacy of silibinin against UVB- induced skin cancer in squamous cell carcinoma (SCC) model of NMSC; currently, we are in advanced stages of developing silibinin formulation for human skin use. Based on findings showing strong silibinin efficacy in mouse skin SCC model, in preliminary studies, we also assessed its effects against UVB-induced BCC. Using Ptch1+/− mouse model of BCC, we observed that silibinin decreases UVB-induced: cyclobutane pyrimidine dimer (CPD) positive cells in ear skin, microscopic BCC formation, dermal mast cell infiltration and bone morphogenetic protein (BMP)-2 gene and protein levels in skin. Furthermore, silibinin decreased: MC9 mast cell chemotactic-migration towards mouse BCC ASZ cells and mucosal mast cell degranulation. Silibinin also decreased proliferation of mouse BCC cells in culture and mouse allografts together with inhibition of mitogenic signaling pathways. In most recent studies, silibinin significantly increased the growth inhibitory effects of Hh pathway inhibitor drugs and reversed the resistance of BCC cells to these drugs via targeting EGFR/AKT and Hh pathway and induction of apoptosis. Based on these highly significant and encouraging findings in BCC models, our hypothesis is that by targeting UVB-induced DNA damage repair and reversal of mast cells-mediated immunosuppressive events, together with modulating signaling pathways associated with drug resistance, silibinin has the potential to be an effective agent for both prevention and adjuvant therapy of BCCs. Our aims are to: I) establish and define the role of silibinin-mediated DNA repair in its preventive efficacy against UVB-induced BCC; II) assess and establish the link between DNA damage repair, mast cells, and reversal of UVB-induced immunosuppression by silibinin in its efficacy against BCC formation; III) further establish the therapeutic efficacy of silibinin against BCC, both alone and in combination with FDA approved anti-BCC therapeutics, and define the associated mechanisms.