Leung Kam
National for Biotechnology Information, NLM, NIH, Bethesda, MD
Integrin receptors are a family of cell-surface heterodimeric glycoproteins that mediate diverse biological events (e.g., cell adhesion, migration, differentiation, proliferation, and apoptosis) involving cell–cell and cell–matrix interactions (1, 2). They consist of an α and a β subunit. They are important for cell adhesion and signal transduction. On the other hand, integrins affect tumor growth, tumor invasiveness, and metastasis (3, 4). The αβ integrin binds mainly to collagen type I, laminins, E-cadherin, and matrix metalloproteinase 1 (5). The αβ integrin is strongly expressed on tumor cells and has been implicated in tumor progression and metastasis (6, 7). In particular, prostate cancer cells and prostate cancer stem cells express high levels of αβ integrin (8, 9). A tetrapeptide sequence consisting of Asp-Gly-Glu-Ala (DGEA) has been identified as a recognition motif used by the type I collagen to bind to αβ integrin (10). DGEA was conjugated with Cy5.5 to study biodistribution of the tracer in prostate tumor-bearing mice (11). Cy5.5-DGEA exhibited high accumulation in αβ-positive PC-3 human prostate tumor cells in nude mice.
整合素受体是一类细胞表面异二聚体糖蛋白，介导涉及细胞间和细胞与基质相互作用的多种生物学事件（如细胞黏附、迁移、分化、增殖和凋亡）(1, 2)。它们由一个α亚基和一个β亚基组成。它们对细胞黏附和信号转导很重要。另一方面，整合素影响肿瘤生长、侵袭和转移(3, 4)。αβ整合素主要与I型胶原、层粘连蛋白、E-钙黏蛋白和基质金属蛋白酶1结合(5)。αβ整合素在肿瘤细胞上强烈表达，并与肿瘤进展和转移有关(6, 7)。特别是，前列腺癌细胞和前列腺癌干细胞高水平表达αβ整合素(8, 9)。由天冬氨酸-甘氨酸-谷氨酸-丙氨酸（DGEA）组成的四肽序列已被确定为I型胶原用于与αβ整合素结合的识别基序(10)。DGEA与Cy5.5偶联，以研究该示踪剂在荷前列腺肿瘤小鼠中的生物分布(11)。Cy5.5-DGEA在裸鼠的αβ阳性PC-3人前列腺肿瘤细胞中表现出高蓄积。
