Anti-ETV4 (aa 100-200) polyclonal antibody

AimsApproximately 60-70% of high-grade round-cell sarcomas that lack the Ewing sarcoma breakpoint region 1 (EWSR1) rearrangement harbour a rearrangement of the CIC gene, most commonly CIC-DUX4. Recent studies have established that CIC-rearranged sarcomas constitute a distinct group characterized by recognizable histology and immunoprofiles, such as positivity for ETV4 and WT1 and negativity for NKX2.2. Although these sarcomas are diagnosed increasingly in practice by fluorescence in-situ hybridization (FISH) with CIC break-apart probes, the optimal modality to diagnose these sarcomas has not been determined. In this study, we describe four round-cell sarcomas that showed false-negative results by CIC break-apart FISH assays. Methods and resultsThese sarcomas showed characteristic histology of CIC-rearranged sarcomas, and all were immunohistochemically positive for ETV4 and WT1 and negative for NKX2.2. Although FISH showed non-atypical negative signals for CIC rearrangement, high-throughput RNA sequencing identified CIC-DUX4 and its fusion breakpoint in all cases. Their clinical and histological findings, as well as fusion points determined by RNA sequencing, did not differ significantly from those of nine FISH-positive CIC-DUX4 sarcoma cases. We estimated that the FISH false-negative rate for CIC-rearranged sarcomas was 14%. Although neither histology nor immunoprofiles (e.g. ETV4 and WT1) are entirely sensitive or specific for CIC-rearranged sarcomas, the observation that these four cases were identified successfully by such phenotypes suggested their practical utility. ConclusionsCIC break-apart FISH assays missed a significant minority of CIC-DUX4 sarcomas, and full awareness of typical morphology and judicious immunohistochemical work-ups, including analyses of ETV4 and WT1, should complement diagnostic assessment.

Overexpression of ETS genes is involved in prostate cancer (PrCa), but there is little information on the non-ERG components of this family. We have investigated ETV1, ETV4, and ETV5 overexpression, with or without PTEN loss, and their association with grade group (GG), pathological stage, focality, and PSA recurrence in PrCa. ETS gene expression was analyzed by qPCR in 104 cases. ETV1 and PTEN immunohistochemistry was assessed in TMA sections from 194 additional cases (PSMAR-Biobank, Barcelona, Spain). ETS mRNA overexpression was found in 23.1%, being ETV1 the most frequently overexpressed (18.3%). ETV1 protein overexpression was detected in 30.4% cases (moderate in 19.6%, strong in 10.8%). PTEN protein expression loss was detected in 36.1% cases and was not associated with ETV1. Strong-moderate ETV1 protein overexpression reaches its highest values in GG3-4, whereas its negativity was significantly more common in GG1 tumors (p = 0.034). ETV1-overexpressing tumors were more often unifocal (p = 0.0007) and high stage (p = 0.032). PTEN loss was less common in GG1 (p = 0.012) and showed a trend to be less frequent in pT2 (p = 0.062) tumors. Strong ETV1 immunostaining (histoscore > 177) was associated with shorter time to PSA recurrence in the univariate (p = 0.002) and in the multivariate analysis (p = 0.018). Moreover, when strong ETV1 overexpression was not combined with PTEN loss, its association with PSA recurrence was even stronger (p = 0.0004). In conclusion, non-ERG ETS overexpression, particularly ETV1 overexpression, has a non-negligible role in PrCa. Strong ETV1 protein expression has a negative impact on prostate cancer outcome that seems to be independent of PTEN status.