Forkhead box (FOX) proteins constitute a family of transcription factors that are evolutionarily conserved in various species ranging from yeast to humans. These proteins have functions during development as well as in adulthood. To date, many reports have described the functions of FOX family genes in cancer cells, but the role of FOXB2 is not well understood. In one of the pancreas ductal adenocarcinoma cell lines, Panc-1 cells, we showed here that FOXB2 expression is barely detectable and that CpG islands in the 5' regions of the FOXB2 are highly methylated. These findings led us to hypothesize that FOXB2 acts as a tumor suppressor. To clarify our hypotheses, we investigated the effects of FOXB2 over-expression in Panc-1 cells. We obtained FOXB2 stable transfectants, and these clones exhibited reduced spheroid formation ability. Expression of β-catenin, which is reported to be over-expressed in various cancer cells, was highly suppressed in FOXB2 stable transfectants. Moreover, side population (SP) cell fractions, which have a high tumorigenesis and metastatic potential, as well as anchorage-independent growth ability, were reduced. These results suggest that FOXB2 has the ability to inhibit the malignant characteristics of Panc-1 in vitro.

中文翻译：

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叉头盒B2在体外抑制胰腺癌细胞系Panc-1的恶性特征。

叉头盒（FOX）蛋白构成了转录因子家族，在从酵母到人类的各种物种中，它们都是进化上保守的。这些蛋白质在发育以及成年期都有功能。迄今为止，许多报道已经描述了FOX家族基因在癌细胞中的功能，但是对FOXB2的作用还不甚了解。在胰腺导管腺癌细胞系之一Panc-1细胞中，我们在这里显示FOXB2的表达几乎无法检测到，并且FOXB2 5'区的CpG岛高度甲基化。这些发现使我们假设FOXB2起到抑癌作用。为了阐明我们的假设，我们研究了Panc-1细胞中FOXB2过表达的影响。我们获得了FOXB2稳定转染子，这些克隆表现出降低的球体形成能力。据报道在各种癌细胞中过表达的β-catenin在FOXB2稳定转染子中被高度抑制。此外，减少了具有高致瘤性和转移潜力以及不依赖贴壁的生长能力的侧群（SP）细胞级分。这些结果表明FOXB2具有体外抑制Panc-1恶性特征的能力。