Estrogen Receptor β and Dormancy in Hepatic Disseminated Colorectal Cancer Cells

肝脏是结肠直肠癌（CRC）中最常见的远处转移部位。在常规治疗下，大约50%的最初局部结直肠癌患者会及时发展为结肠肝转移（CLM）；男性的风险更高。即使在非常早期（UICC I期）和完全（R0）切除后，约6%的患者在诊断后10年内仍会患上CLM。在无复发生存期为5年后，大约有2.5%的患者在初始治疗后10年内不会发展为晚期CLM。CLM发生前的这种长潜伏期表明肝脏中存在大量弥散性的、不活跃的、临床不明显的肿瘤细胞，即使在辅助治疗后，这些细胞仍保留了转移性生长的潜力。现在人们认为这些细胞进入了一种叫做休眠的休眠程序，这还没有得到广泛的研究。雌激素受体β (ERβ)是CRC中该程序激活的潜在开关。ERβ阳性结直肠原发肿瘤表现出更好的长期生存率。先前的研究表明，表达ERβ的结直肠癌患者肝转移的风险较低。体外实验还证明了较低的增殖率，诱导细胞周期阻滞，并通过ERβ激活已知的促休眠信号。这些结果表明，ERβ阳性肿瘤细胞（循环和播散性肿瘤细胞（CTC/DTC））可能通过ERβ信号激活休眠程序。因此，ERβ可能是一个有趣的、潜在的易于操纵的靶标，以保持播散性癌细胞在体内处于休眠状态。在本研究中，我们首先想要阐明ERβ表达对人类CRC和CLM患者转移时间（同步或异时）的影响。在此之后，我们将首次使用体内CAM-assay（禽绒毛膜-尿囊膜模型）来诱导并随后从肝脏（DTC）和血液（CTC）中分离出gfp标记的表达ERβ的CRC细胞。申请人在使用CAM-assay，以及CTC和DTC的检测和分离方面都有丰富的经验。临床验证的ERβ激动剂（ERB-041）和实验验证的拮抗剂（PHTPP）已经商业化，这将使ERβ的体内操纵成为可能，从而探索ERβ对CRC ctc和肝脏dtc诱导休眠的影响。本研究的结果可能用于该治疗的潜在临床评价。

The liver is by far the most common site of distant metastasis in colorectal cancer (CRC). Following conventional therapy, roughly 50% of patients suffering from initially localized CRC will develop colorectal liver metastasis (CLM) in time; the risk is higher for men. Even in very early-stage (UICC Stage I) and following complete (R0) resection, ca. 6% of patients will suffer from CLM within 10 years of diagnosis. Following recurrence free survival of 5 years, roughly 2,5% of patients will never-the less develop late CLM, at times 10 years after initial treatment. This long latency until CLM occurs indicates the presence of a pool of disseminated, inactive, clinically not overt tumor cells in the liver, which retain their potential for metastatic outgrowth even following adjuvant therapies. It is now believed that these cells have entered a quiescence program called Dormancy, which is not yet studies extensively. The estrogen receptor β (ERβ) is a potential switch for the activation of this program in CRC. ERβ positive colorectal primary tumors showed a better long-term survival. Previous research indicates a lower risk of liver metastasis in patients with ERβ expressing CRC. In-vitro experiments additionally demonstrated a lower proliferation rate, an induction of cell-cycle arrest and the activation of known pro-dormancy signaling through ERβ activation. These results indicate that ERβ positive tumor cells (circulating and disseminated tumor cells (CTC/DTC)) may activate a dormancy program through ERβ signaling. The ERβ may thus be an interesting and potentially easy to manipulate target to keep disseminated cancer cells in a state of dormancy in-vivo. In this proposal, we first want to elucidate the influence of ERβ expression on metastasis chronology (synchronous vs. metachronous) in a cohort of human CRC and CLM. Following this, we will be the first to use the in-vivo CAM-assay (avian chorioallantoic membrane model) to induce and subsequently isolate GFP-marked ERβ expressing CRC cells from the liver (DTC) and the blood (CTC). The applicant has ample experience with both the use of the CAM-assay, as well as the detection and isolation of CTC and DTC. The fact that a clinically validated ERβ agonist (ERB-041) and an experimentally very well-established antagonist (PHTPP) are commercially available will enable the in-vivo manipulation of the ERβ and thus the exploration of the influence on dormancy induction in CRC CTCs and hepatic DTCs. The results from this study may be of use in the potential clinical evaluation of this treatment.