VIVA1: A more Invasive Subclone of MDA-MB-134VI Invasive Lobular Carcinoma Cells With Increased Metastatic Potential in Xenograft Models. VIVA1: A more Invasive Subclone of MDA-MB-134VI Invasive Lobular Carcinoma Cells With Increased Metastatic Potential in Xenograft Models

Invasive Lobular Carcinoma (ILC) is the second most common type of breast cancer next to invasive ductal carcinoma (IDC). Few research tools exist to study ILC metastasis in vivo, with only one cell line reported to grow in xenograft models. We thus set out to isolate and characterize ILC cells with increased invasive properties and establish a xenograft model that spontaneously metastasized from the orthotopic site. MDA-MB-134VI ILC cells were placed in Matrigel transwells for 7-days. Migrated cells were isolated and expanded to create the VIVA1 cell line. VIVA1 cells were tested in vitro for ILC marker expression and relative proliferative and invasive ability compared to parental MDA-MB-134VI cells. An intraductally injected orthotopic xenograft model was used to assess primary and metastatic tumor growth in vivo. Similar to MDA-MB-134VI, VIVA1 cells retained expression of ER and lacked expression of E-cadherin, however showed increased invasion in vitro. Following intraductal injection, VIVA1 and MDA-MB-134VI cells had similar primary tumor growth similar survival kinetics. However, macrometastases were apparent in 6/10 animals at clinical endpoint in VIVA1 injected animals. RNA-seq analysis showed gene expression changes consistent with differences in cell migration and survival. Cells from the primary orthotopic tumor (VIVA-LIG43) were isolated and re-injected intraductally, which led to tumor growth in the mammary glands with a more rapid onset than the parental VIVA1 cells. Overall design: polyA mRNA sequencing of 134VI and VIVA (n=2) cell lines

浸润性小叶癌（Invasive Lobular Carcinoma, ILC）是仅次于浸润性导管癌（Invasive Ductal Carcinoma, IDC）的第二大常见乳腺癌亚型。当前可用于体内研究ILC转移的研究工具极为匮乏，仅有一种细胞系被报道可在异种移植模型中增殖。为此，本研究旨在分离并鉴定具有更高侵袭特性的ILC细胞，同时构建一个可从原位位点自发发生转移的异种移植模型。将MDA-MB-134VI ILC细胞接种于基质胶（Matrigel）包被的Transwell小室中培养7天，收集迁移的细胞并进行扩增，以此构建VIVA1细胞系。以亲本MDA-MB-134VI细胞为对照，在体外检测VIVA1细胞的ILC标志物表达水平、相对增殖能力与侵袭能力。采用导管内注射的原位异种移植模型，评估体内原发肿瘤与转移性肿瘤的生长情况。与MDA-MB-134VI细胞一致，VIVA1细胞保留了雌激素受体（ER）的表达，且不表达E-钙粘蛋白（E-cadherin），但体外侵袭能力显著提升。导管内注射后，VIVA1与MDA-MB-134VI细胞的原发肿瘤生长速率及存活动力学无明显差异。然而，在实验终点时，VIVA1注射组的10只受试动物中有6只出现了明显的大转移灶。RNA测序（RNA-seq）分析显示，两组细胞的基因表达变化与细胞迁移和存活能力的差异相一致。从原位原发肿瘤中分离得到的细胞（VIVA-LIG43）经再次导管内注射后，可在乳腺内形成肿瘤，且肿瘤发生速度较亲本VIVA1细胞更快。总体实验设计：对134VI与VIVA细胞系（n=2）开展polyA信使RNA（mRNA）测序。