Role of Reishi on cell surface proteins and signaling modulation in IBC

描述（由申请人提供）：炎症性乳腺癌（IBC）是最致命的乳腺癌之一，患者在接受手术或放射治疗后的5年生存率不到5%。IBC细胞分泌分化因子，刺激血管生成，并以肿瘤栓塞的形式侵入新生血管。在IBC中，栓子在穿过血管并停留在真皮淋巴结内时保持细胞与细胞的附着，导致IBC炎症表型。尽管决定IBC侵袭的分子变化仍有待完全阐明，但IBC细胞系和人组织过表达E-cadherin、表皮生长因子受体（Epidermal Growth Factor Receptor， EGFR）和人表皮生长因子2 （human Epidermal Growth Factor 2, HER2）这些与维持肿瘤球体完整性相关的细胞表面蛋白，增加了IBC肿瘤的生长速度、侵袭和转移。由于IBC肿瘤细胞栓塞比单个细胞更容易形成转移，并且对化疗和放疗更有抵抗力，因此用一种能够分解细胞球体的化合物来预防IBC似乎是可行的。我们最近发表的一篇文章称，中药中使用的灵芝（Ganoderma lucidum, Reishi）选择性地抑制IBC细胞的活力，但对非癌性乳腺上皮细胞的活力没有抑制作用。同时,我们

DESCRIPTION (provided by applicant): Inflammatory Breast Cancer (IBC) is one of the most lethal forms of breast cancer, where patients show less than a five percent survival rate beyond five years when treated with surgery or radiation therapy. IBC cells secrete differentiation factors, stimulate vasculogenesis, and invade as tumor emboli located within a de novo formed vessel. In IBC, the embolus maintains cell-cell attachments as it moves through the vessel and lodges within a dermal lymph node, causing the IBC inflammatory phenotype. Although the molecular changes that dictate IBC invasion remain to be fully elucidated, IBC cell lines and human tissues, overexpress E-cadherin, Epidermal Growth Factor Receptor (EGFR), and Human Epidermal Growth Factor 2 (HER2) which are cell surface proteins associated with maintaining tumor spheroid integrity, increase IBC tumor growth rate, and invasion and metastasis. Since IBC tumor cell emboli are more efficient at forming metastases and are more resistant to chemo and radiotherapy than single cells, it seems feasible to prevent IBC with a compound that has the ability to disintegrate the cell spheroids. We recently published that Ganoderma lucidum (Reishi), a mushroom used in Traditional Chinese Medicine, selectively inhibits IBC cell viability, but not viability of non- cancerous mammary epithelial cells. Also, we have shown that Reishi inhibits the expression of key proteins important in IBC progression, and tumor spheroid fomation. The main hypothesis of the present proposal is that Reishi inhibits cell surface protein expression, which contributes to disintegration of the tumor spheroids that are created during IBC progression, resulting in invasion inhibition combined with altered intracellular signaling. In support of this hypothesis, preliminary studies in our laboratory showe that Reishi 1) downregulates a number of cancer promoting molecules, 2) Reishi inhibits EGFR and E-cadherin protein abundance in vitro and in vivo. 3) Reishi inhibits IBC tumor growth and tumor weight in severe combined immunodeficient (SCID) mice by 58% and 45%, respectively. We propose that Reishi downregulates the expression of cell surface proteins involved in the progression of IBC and chemosensitize the IBC cells to EGFR/HER2 therapy treatment. Therefore, the main goal of this proposal is to validate the inhibitory role of Reishi on IBC progression via the inhibition of plasma membrane (PM) proteins and subsequent EGFR intracellular signaling events. To test our hypothesis, we propose 1) to isolate and identify PM proteins in non- cancerous mammary epithelial cells and in IBC cells treated with Reishi and 2) to investigate the therapeutic potential of Reishi in IBC cells, focusing on EGFR/HER2 signaling cascades. The proposed dissection of the molecular mechanisms of IBC is expected to significantly advance the current understanding and development of targeted therapeutic agents for IBC as well as contribute to a rapid and accurate diagnosis of this mortal disease.