The presence of sarcomatoid or rhabdoid features (which are associated with advanced disease and poor prognosis) is rarely observed in the subtypes of renal cell carcinoma (RCC). The SWI/SNF chromatin-remodeling complex, which is composed of evolutionarily conserved core subunits including SMARCB1/INI1 (SMARCB1), SMARCA4/BRG1 (SMARCA4), SMARCC1/BAF155 (SMARCC1), and SMARCC2/BAF170 (SMARCC2), can be regarded as the prototype of an epigenetic regulator of gene expression that is involved in tumor suppression. We analyzed the histological, immunohistochemical, and clinicopathological status in 72 cases of RCC with sarcomatoid or rhabdoid features, focusing on the expression status of the subunits of SWI/SNF chromatin-remodeling complex proteins. Cases with lost or reduced expression were defined as showing aberrant expression. The frequency of aberrant SMARCA4 immunoexpression of a sarcomatoid or rhabdoid component in clear cell RCC (ccRCC) (47/50, 94%) was significantly higher than that in non-ccRCC (4/9, 44%) (p < 0.001). In ccRCC without sarcomatoid or rhabdoid features, aberrant SMARCA4 immunoexpression was observed in 33 of 48 (67%) cases. Immunoreactivities for SMARCB1, SMARCA2, and SMARCC2 were retained in almost all subtypes of RCC. The patients with aberrant SMARCA4 expression in RCC with sarcomatoid or rhabdoid features achieved shorter progression-free survival compared with the patients with retained SMARCA4 expression (all subtypes of RCC, p = 0.0212; ccRCC, p = 0.0265). These results suggest that in ccRCC, aberrant SMARCA4 expression is one of the adverse prognostic factors or a high-grade malignant transforming factor. The evaluation of SMARCA4 immunoexpression may be a useful diagnostic tool to help distinguish ccRCC from non-ccRCC.

中文翻译：

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具有肉瘤样或横纹肌样特征的肾细胞癌中SWI / SNF染色质重塑的复杂状态。

在肾细胞癌（RCC）的亚型中，很少观察到肉瘤样或横纹肌样特征（与晚期疾病和预后不良相关）。可以认为SWI / SNF染色质重塑复合物由进化保守的核心亚基组成，包括SMARCB1 / INI1（SMARCB1），SMARCA4 / BRG1（SMARCA4），SMARCC1 / BAF155（SMARCC1）和SMARCC2 / BAF170（SMARCC2）作为涉及肿瘤抑制的基因表达的表观遗传调控因子的原型。我们分析了72例具有肉瘤或横纹肌样特征的RCC的组织学，免疫组化和临床病理学状态，重点研究了SWI / SNF染色质重塑复合蛋白亚基的表达状态。表达缺失或减少的病例定义为表现出异常表达。透明细胞RCC（ccRCC）中肉瘤样或横纹肌成分异常SMARCA4免疫表达的频率（47/50，94％）显着高于非ccRCC（4/9，44％）（p <0.001）。在无肉瘤样或横纹肌样特征的ccRCC中，在48例病例中有33例（67％）观察到异常的SMARCA4免疫表达。几乎所有RCC亚型都保留了SMARCB1，SMARCA2和SMARCC2的免疫反应性。与保留SMARCA4表达的患者相比，RCC中具有肉瘤样或横纹肌特征的SMARCA4表达异常的患者实现了更短的无进展生存期（RCC的所有亚型，p = 0.0212； ccRCC，p = 0.0265）。这些结果表明，在ccRCC中，异常的SMARCA4表达是不良预后因素之一或高级别恶性转化因子。