Department of Diagnostic and Public Health, Section of Pathology, University of Verona, Verona, Italy.
Department of Pathology, Pederzoli Hospital, Peschiera del Garda, Verona, Italy.
Mod Pathol. 2019 Feb;32(2):258-268. doi: 10.1038/s41379-018-0128-1. Epub 2018 Sep 11.
Amplification of vascular endothelial growth factor A (VEGFA) has been recently reported in TFEB-amplified renal cell carcinomas regardless the level of TFEB amplification. We sought to determine VEGFA amplification by fluorescent in situ hybridization (FISH) and VEGFA mRNA expression by in situ hybridization (RNAscope 2.5) in a series of 10 renal cell carcinomas with TFEB gene alterations, either amplification and/or rearrangement (t(6;11) renal cell carcinoma). TFEB gene rearrangement was demonstrated in eight cases, whereas the remaining two cases showed a high level of TFEB (> 10 copies of fluorescent signals) gene amplification without evidence of rearrangement. Among the eight t(6;11) renal cell carcinomas (TFEB-rearranged cases), one case displayed a high level of TFEB gene amplification and two showed increased TFEB gene copy number (3-4 copies of fluorescent signals). Those three cases behaved aggressively. By FISH, VEGFA was amplified in all three cases with TFEB amplification and increased VEGFA gene copy number was observed in the two aggressive cases t(6;11) renal cell carcinomas with an overlapping increased number of TFEB fluorescent signals. Overall, VEGFA mRNA expression was observed in 8 of 10 cases (80%); of these 8 cases, 3 cases showed high-level TFEB amplification, one case showed TFEB rearrangement with increased TFEB gene copy number, whereas four showed TFEB gene rearrangement without increased copy number. In summary, VEGFA amplification/increased gene copy number and VEGFA mRNA expression occur in TFEB-amplified renal cell carcinoma, but also in a subset of t(6;11) renal cell carcinoma demonstrating aggressive behavior, and in unamplified conventional t(6;11) renal cell carcinoma suggesting VEGFA as potential therapeutic target in these neoplasms even in the absence of TFEB amplification. We finally propose that all the renal tumors showing morphological characteristics suggesting t(6;11) renal cell carcinoma and all unclassified renal cell carcinomas, either high grade or low grade, should immunohistochemically be evaluated for cathepsin K and/or Melan-A and if one of them is positive, tested for TFEB gene alteration and VEGFA gene amplification.
血管内皮生长因子 A(VEGFA)的扩增最近已在 TFEB 扩增的肾细胞癌中被报道,而不论 TFEB 扩增的程度如何。我们试图通过荧光原位杂交(FISH)来确定 10 例 TFEB 基因改变的肾细胞癌(包括扩增和/或重排(t[6;11]肾细胞癌))中 VEGFA 的扩增,并通过原位杂交(RNAscope 2.5)来检测 VEGFA mRNA 的表达。在 8 例病例中证明了 TFEB 基因重排,而另外 2 例则显示高水平的 TFEB(> 10 个荧光信号拷贝)基因扩增而没有重排的证据。在 8 例 t[6;11]肾细胞癌(TFEB 重排病例)中,1 例显示高水平的 TFEB 基因扩增,2 例显示 TFEB 基因拷贝数增加(3-4 个荧光信号拷贝)。这 3 例病例表现出侵袭性。通过 FISH,在所有 3 例 TFEB 扩增的病例中均扩增了 VEGFA,并且在 2 例具有重叠增加的 TFEB 荧光信号的侵袭性 t[6;11]肾细胞癌中观察到增加的 VEGFA 基因拷贝数。总体而言,在 10 例病例中的 8 例(80%)中观察到 VEGFA mRNA 表达;在这 8 例中,3 例显示高水平 TFEB 扩增,1 例显示 TFEB 重排且 TFEB 基因拷贝数增加,而 4 例显示 TFEB 基因重排而无拷贝数增加。总之,VEGFA 扩增/增加基因拷贝数和 VEGFA mRNA 表达发生在 TFEB 扩增的肾细胞癌中,但也发生在具有侵袭性行为的 TFEB 重排的一部分 t[6;11]肾细胞癌中,并且在未扩增的常规 t[6;11]肾细胞癌中提示 VEGFA 作为这些肿瘤的潜在治疗靶点,即使在没有 TFEB 扩增的情况下也是如此。我们最后提出,所有表现出提示 t[6;11]肾细胞癌的形态特征的肾肿瘤以及所有未分类的肾细胞癌,无论是高级别还是低级别,都应该进行组织化学 cathepsin K 和/或 Melan-A 评估,如果其中一种为阳性,则应检测 TFEB 基因改变和 VEGFA 基因扩增。