Development of a Cathepsin V inhibitor for application as an anti-tumour agent.

尽管在过去的25年中生存率有所提高，但每5名被诊断为雌激素受体阳性（ER+）乳腺癌的女性中就有1人会死于这种疾病。ER+肿瘤通常对内分泌（激素）治疗反应良好，但许多肿瘤随后对这些标准治疗产生耐药性，导致疾病复发，转移和死亡。复发性、耐药性和转移性ER+乳腺癌的替代治疗选择非常有限，突出了为这些患者开发改进的治疗策略的主要未满足的临床需求。本提案的主要目的是开发针对半胱氨酸蛋白酶组织蛋白酶V（CTSV）的小分子抑制剂，我们已确定其为ER+乳腺癌的新治疗靶点。由于CTSV在生理条件下（睾丸和胸腺）的有限表达和特定的病理功能，CTSV是一个有吸引力的治疗靶点。原发性乳腺肿瘤中CTSV表达升高与远处转移和疾病复发相关，而浸润前乳腺导管原位癌（DCIS）组织中CTSV表达升高与浸润性疾病进展相关。我们实验室内的研究集中在解剖CTSV在ER+乳腺癌中的作用。我们发现CTSV的高表达与ER+乳腺癌的不良预后相关，在ER+乳腺癌中，CTSV促进肿瘤细胞增殖和侵袭。我们还发现CTSV驱动GATA 3降解并提高细胞外ATP水平（eATP），这两者都促进乳腺癌转移。在我们的实验室之外，研究已经表明CTSV蛋白水解活性在抑制免疫细胞细胞毒性中是至关重要的，因此CTSV抑制剂可以通过增强免疫细胞的细胞毒性而作为肿瘤细胞免疫治疗方法。总的来说，这项研究支持进一步检查CTSV作为乳腺癌的治疗靶点是必要的。为了实现这一点，我们必须开发一种抑制CTSV蛋白水解活性的化合物。我们已经鉴定了一种对CTSV具有效力和选择性的小分子抑制剂，并且该项目将专注于该分子的精制和改进。我们将使用结构-活性关系（SAR）合成方法来确定我们生成的抑制剂的化学结构与通过选择性抑制CTSV对生物活性的影响之间的关系。先导化合物将在一系列基于细胞的测定中进行验证，以确定最有效和最具选择性的命中化合物的功能。

Despite improved survival rates over the last 25 years, 1 in 5 women diagnosed with Estrogen Receptor positive (ER+) breast cancer will die from their disease. ER+ tumours generally respond well to endocrine (hormone) therapy, however many tumours subsequently develop resistance to these standard treatments, resulting in disease recurrence, metastasis and death. Alternative treatment options for recurrent, resistant and metastatic ER+ breast cancer is severely limited, highlighting the major unmet clinical need to develop improved therapeutic strategies for these patients.The main aim of this proposal is to develop a small molecule inhibitor targeting cysteine protease Cathepsin V (CTSV), which we have identified as a novel therapeutic target in ER+ breast cancer. CTSV is an attractive therapeutic target due to its restricted expression under physiological conditions (testis and thymus) and specific pathological functions. Elevated CTSV expression in primary breast tumours has previously been correlated with the presence of distant metastasis and disease recurrence, while elevated CTSV expression in pre-invasive breast ductal carcinoma in situ (DCIS) tissue has been correlated with progression to invasive disease. Research within our laboratory has focused on dissecting the role of CTSV in ER+ breast cancer. We have discovered elevated expression of CTSV is associated with poor prognosis in ER+ breast cancer, where it promotes tumour cell proliferation and invasion. We have also identified that CTSV drives GATA3 degradation and enhances extracellular ATP levels (eATP), both of which promote breast cancer metastasis. Beyond our laboratory, research has illustrated that CTSV proteolytic activity is crucial in suppressing immune cell cytotoxicity, therefore CTSV inhibitors could have utility as a tumour cell immunotherapy approach by enhancing immune cell cytotoxicity. Collectively, this research supports that further examination of CTSV as a therapeutic target in breast cancer is warranted. To achieve this, it is imperative that we develop a compound that inhibits CTSV proteolytic activity. We have identified a small molecule inhibitor that exhibits potency and selectivity towards CTSV, and this project will focus on the refinement and improvement of this molecule. We will use a structure-activity relationship (SAR) synthesis approach to determine the relationship between the chemical structure of the inhibitors we generate and the resultant impact on biological activity through selective inhibition of CTSV. Lead compounds will be validated in a series of cell-based assays to determine the functionality of the most potent and selective hit compounds.