Immunology Research Center, Institute of Immunology and Infectious Diseases, Iran University of Medical Sciences, Tehran, Iran; Reproductive Biotechnology Research Center, Avicenna Research Institute, ACECR, Tehran, Iran.
Oncopathology Research Center, Iran University of Medical Sciences, Tehran, Iran; Department of Molecular Medicine, Faculty of Advanced Technologies in Medicine, Iran University of Medical Sciences, Tehran, Iran.
Exp Mol Pathol. 2021 Aug;121:104654. doi: 10.1016/j.yexmp.2021.104654. Epub 2021 Jun 1.
Breast cancer (BC) is the most common cancer in females. In this regard, the identification of molecular alterations driving BC is an immediate need for developing effective immunotherapeutic tools. Here we investigated the expression of a placenta-specific protein, Retrotransposon-like 1 (RTL1) in a series of BC tissues and cell lines. RTL1-specific polyclonal antibody was generated and characterized. Using tissue microarray immunohistochemistry, expression of RTL1 in a total of 147 BC and 36 non-malignant breast tissues was investigated and the association of patient's clinicopathological parameters with RTL1 expression was then examined. Expression of RTL1 in four BC cells was assessed by flow cytometry, immunofluorescent staining and Western blotting. We observed a mixture pattern of nuclear and cytoplasmic RTL1 expression in most tissues examined, however nuclear expression was found to be dominant pattern of expression. The level of nuclear RTL1 expression was significantly higher in BC tissues (P < 0.001). A statistically significant association between nuclear RTL1 expression and histological grade and vascular invasion was found (P < 0.001 and P < 0.05). All cell lines expressed RTL1 with varying degrees at their surface. The most invasive BC cell line MDA-MB-231, compared to T-47D, SKBR3 and MCF7 expressed higher levels of RTL1 at their surface. Cells with a low level of surface expression, expressed high levels of intracellular RTL1 expression. Our antibody reacted with a specific band of about 125 KD in normal human placenta and all cell lines examined. In contrast to placenta, two additional bands were also observed in cancer cell lines. Our results showed for the first time that RTL1 is differentially expressed in BC compared to non-malignant breast tissues and is associated with a higher grade and vascular invasion. In BC cells with high metastatic and invasive potential, this antigen is mostly confined to cell surface compartment indicating the possibility of using antibody-based immunotherapy for advanced metastatic BC patients.
乳腺癌（BC）是女性中最常见的癌症。在这方面，确定驱动 BC 的分子改变是开发有效免疫治疗工具的当务之急。在这里，我们研究了胎盘特异性蛋白 Retrotransposon-like 1（RTL1）在一系列 BC 组织和细胞系中的表达。生成并表征了 RTL1 特异性多克隆抗体。使用组织微阵列免疫组织化学，研究了总共 147 例 BC 和 36 例非恶性乳腺组织中 RTL1 的表达，并检查了患者临床病理参数与 RTL1 表达的关联。通过流式细胞术、免疫荧光染色和 Western blot 评估了 RTL1 在四种 BC 细胞中的表达。我们观察到大多数检查的组织中存在核和细胞质 RTL1 表达的混合模式，但核表达是主要的表达模式。BC 组织中核 RTL1 表达水平显着升高（P <0.001）。核 RTL1 表达与组织学分级和血管浸润之间存在统计学显着关联（P <0.001 和 P <0.05）。所有细胞系均在其表面以不同程度表达 RTL1。与 T-47D、SKBR3 和 MCF7 相比，具有最高侵袭性的 BC 细胞系 MDA-MB-231 在其表面表达更高水平的 RTL1。表面表达水平低的细胞表达高水平的细胞内 RTL1 表达。我们的抗体与人正常胎盘和所有检查的细胞系反应，产生约 125 KD 的特异性条带。与胎盘不同，在癌细胞系中还观察到另外两条带。我们的结果首次表明，与非恶性乳腺组织相比，RTL1 在 BC 中差异表达，并且与更高的分级和血管浸润相关。在具有高转移和侵袭潜力的 BC 细胞中，这种抗原主要局限于细胞表面区室，表明有可能对晚期转移性 BC 患者进行基于抗体的免疫治疗。
