Abstract 3992: Comparison of AKR1B10, 2SC, and FH as biomarkers for HLRCC detection
Authors: Ahvenainen Terhi , Uimari Outi , Ahtikoski Anne , Kämpjärvi Kati , Bützow Ralf , Vahteristo Pia 
Published: August 2019

Abstract
HLRCC is an autosomal dominant tumor predisposition syndrome characterized by cutaneous and uterine leiomyomas (ULs), and increased risk for aggressive type 2 papillary renal cell carcinoma (RCC). The syndrome is caused by germline mutations in fumarate hydratase (FH). Loss of FH causes dysfunction of the Crebs cycle and an increase of succinated proteins, which can be detected using anti-2-succinocysteine (2SC) antibody. Recently, we have observed that aldo-keto reductase family 1, member B10 (AKR1B10) is overexpressed in RNA-level in ULs with biallelic loss of FH. Here, we compared anti-AKR1B10, anti-2SC, and anti-FH antibodies in detection of FH loss in protein-level in HLRCC-associated ULs.
The study material consisted of 142 formalin-fixed paraffin-embedded (FFPE) UL samples collected at the University hospitals in Finland. The sample series include 77 FH-deficient UL samples from 25 HLRCC patients and 65 sporadic conventional ULs. HLRCC background was verified by detected germline mutation of FH. Four 0.8 mm cores of representative FFPE tumor tissue were used to construct tissue microarrays. Immunohistochemistry (IHC) was executed using an anti-AKR1B10 (1:300, H00057016-M01, Abnova), anti-2SC (1:2000, provided by Dr. Norma Frizzell), and anti-FH (1:1000, sc-100743, Santa Cruz Biotechnology, Inc) antibodies. Expression was detected by BrightVision (Immunologic) and DAB Quanto (Thermo Fisher Scientific) systems. Pathologist specialized in gynecological pathology evaluated the IHC staining from the smooth muscle tumor cells.
AKR1B10 and 2SC detected all 77 HLRCC samples. AKR1B10 displayed either mild (12/77, 16%) or strong (65/77, 84%) expression and succination level was strong in all cases. Loss of FH expression was displayed in 68/77 (88%) of the FH-deficient ULs. All conventional ULs displayed negative AKR1B10 and 2SC staining and expressed FH. FH was expressed either mildly (15/65, 23%) or strongly (50/65, 77%) in the samples.
Reliable methods for FH-deficient UL detection in the clinics are currently lacking. Here, comparison of AKR1B10, 2SC, and FH showed that all three biomarkers identified HLRCC-ULs with 100% specificity. The sensitivity was 100% with AKR1B10 and 2SC, and 88% with FH. It seems that even with known mutation in FH, in some cases the likely inactive protein is retained in tumor cells and is thus detectable by anti-FH.
To conclude, we show that anti-AKR1B10 and anti-2SC detect FH-deficient ULs with 100% specificity and sensitivity. Anti-FH is lacking sensitivity in 12% of HLRCC cases. Reliable detection of FH-deficient ULs enables the patients and their families to be directed to genetic counseling, family planning, and regular renal monitoring.
Citation Format: Terhi Ahvenainen, Outi Uimari, Anne Ahtikoski, Kati Kämpjärvi, Ralf Bützow, Pia Vahteristo. Comparison of AKR1B10, 2SC, and FH as biomarkers for HLRCC detection [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3992.