Background

Formin-related protein-1(FRL1) has reportedly been overexpressed in a variety of malignancies, such as clear cell renal cell carcinoma (ccRCC). However, the clinical value and molecular mechanisms underlying ccRCC tumorigenesis and progression in association with FRL1 remain poorly understood.

Methods

Immunohistochemical analysis was performed on 119 paraffin-embedded RCC tissue samples to detect FRL1 expression and analyze its prognostic value. Colony formation, the CCK-8 assay, flow cytometry, and in vivo nude mice subcutaneous experiments were used to identify the effects of FRL1 on growth and proliferation. In vitro tests for wound healing, migration, and invasion were used to assess the involvement of FRL1 in invasion and metastatic potential. The process of epithelial-mesenchymal transition process (EMT) and the MMP2 expression were detected in stably transfected RCC cells via western blotting, as well as in tumor tissue paraffin sections from xenograft model.

Results

Both FRL1 mRNA and protein levels were noticeably elevated in ccRCC cell lines and samples. Aberrant overexpression of FRL1 was associated with unfavorable clinicopathological features of ccRCC and indicated poor prognosis. Ectopic overexpression of FRL1 increased the growth-promoting traits of ccRCC cells as well as the migratory and invasive capacity of RCC cells, whereas FRL1-silencing caused the opposite results. In addition, FRL1 promoted epithelial-mesenchymal transition (EMT) and upregulated the expression of matrix metalloproteinase 2 (MMP2). Finally, overexpression of FRL1 upregulated phosphorylation level of ERK1/2 with no effect on total level of ERK1/2 in the RCC cells. MAPK/ERK inhibitor reversed the promotional effects of FRL1.

Conclusion

FRL1 was overexpressed in ccRCC tissues and predicted poor prognosis. FRL1 contributes to invasion and aggressive phenotype of ccRCC by facilitating EMT through MAPK/MMP2 axis.

中文翻译：

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Formin相关蛋白1通过MAPK/MMP2途径促进透明细胞肾细胞癌的增殖和侵袭表型

背景

据报道，Formin 相关蛋白 1 (FRL1) 在多种恶性肿瘤中过度表达，例如透明细胞肾细胞癌 (ccRCC)。然而，与 FRL1 相关的 ccRCC 肿瘤发生和进展的临床价值和分子机制仍知之甚少。

方法

对119例石蜡包埋的肾细胞癌组织样本进行免疫组织化学分析，检测FRL1的表达并分析其预后价值。使用集落形成、CCK-8测定、流式细胞术和体内裸鼠皮下实验来鉴定FRL1对生长和增殖的影响。使用伤口愈合、迁移和侵袭的体外测试来评估 FRL1 在侵袭和转移潜力中的参与。通过蛋白质印迹法检测稳定转染的肾细胞癌细胞以及异种移植模型的肿瘤组织石蜡切片中的上皮-间质转化过程（EMT）和MMP2表达。

结果

在 ccRCC 细胞系和样本中，FRL1 mRNA 和蛋白质水平均显着升高。FRL1 的异常过度表达与 ccRCC 的不良临床病理特征相关，并表明预后不良。FRL1的异位过度表达增加了ccRCC细胞的生长促进特性以及RCC细胞的迁移和侵袭能力，而FRL1沉默导致了相反的结果。此外，FRL1促进上皮间质转化（EMT）并上调基质金属蛋白酶2（MMP2）的表达。最后，FRL1 的过表达上调了 RCC 细胞中 ERK1/2 的磷酸化水平，但对 ERK1/2 的总水平没有影响。MAPK/ERK 抑制剂逆转了 FRL1 的促进作用。

结论

FRL1 在 ccRCC 组织中过度表达，预示预后不良。FRL1 通过 MAPK/MMP2 轴促进 EMT，从而促进 ccRCC 的侵袭和侵袭表型。