Cytoplasmic expression of β-catenin is an independent predictor of progression of conventional renal cell carcinoma: a simple immunostaining score

Association of the combined parameters including the frequency of primary cilia, PD-L1, Smoothened protein, membranous β-catenin and cytoplasmic β-catenin expression with the outcome of patients with clear cell renal cell carcinoma

AIMS

The objective of this study was to investigate the association and combined prognostic significance of the PD-L1, Smoothened protein and β-catenin expressions in patients with clear cell renal cell carcinoma (ccRCC).

METHODS

The PD-L1, Smoothened protein and β-catenin expression were evaluated in 104 ccRCC patients. All studied tumor samples were acquired from nephrectomy specimens of primary tumors and not from biopsies or metastases. An indirect immunohistochemistry using polyclonal rabbit anti-Smoothened antibody, monoclonal mouse anti-human β-catenin-1 antibody, immunohistochemical assay PD-L1 28-8 pharmDx using monoclonal rabbit anti-PD-L1 antibody and anti-VHL (C- terminal) rabbit antibody was used. Immunohistochemistry was scored semiquantitavely.

RESULTS

Median overall survival (OS) was significantly better in patients with lower PD-L1 expression (≤5%), Smoothened protein (SMO) expression (<5%) or cytoplasmic β-catenin expression (≤75%) than in patients with higher expressions of these biomarkers (P<0.001, P=0.047, and P<0.001, respectively). Membranous β-catenin showed an opposite effect with its lower expression (≤75%) being associated with longer OS (P=0.020). There was significant association between PD-1 and PD-L1 expression (P=0.007) and significant association of tumor grade (WHO 2016) with membranous β-catenin (P<0.001), cytoplasmic β-catenin (P=0.005), pVHL (P=0.042), PD-L1 (P=0.049) and PD-1 (P=0.028) expression.

CONCLUSION

The present study provides the first data on the potential association and combined prognostic significance of frequency of primary cilia, PD-L1, Smoothened protein and β-catenin expression with the outcome in clear cell renal cell carcinoma.

RNF43 as a predictor of malignant transformation of pancreatic mucinous cystic neoplasm

Mucinous cystic neoplasm (MCN) of the pancreas rarely progresses to invasive carcinoma, but few studies have analyzed genomic alterations involved in its malignant transformation. The relationships of ring finger protein 43 (RNF43) mutations with cytological atypia, RNF43 protein expression, and Wnt signaling proteins in MCN remain unclear. This study included 106 MCN cases, classified into 89 low-grade dysplasia (LG), 9 high-grade dysplasia (HG), and 8 invasive carcinoma (INV). We analyzed HG/INV and LG lesions of 9 HG/INV cases and LG lesions of 9 LG cases using targeted sequencing and confirmed the protein expression of RNF43 and β-catenin. The frequency of RNF43 mutations was significantly higher in HG/INV cases than in LG cases. Furthermore, HG/INV lesions (56%) and LG lesions (33%) of HG/INV cases possessed RNF43 mutation, whereas no such mutation was detected in any LG cases. The expression of RNF43 was reduced in 71% of HG/INV cases and significantly correlated with histological grade and aberrant expression of β-catenin. In 3 of 5 RNF43-mutated cases, the expression of RNF43 was reduced, but there was no significant correlation between RNF43 mutation and protein expression. MCNs frequently harbored KRAS mutations, at rates of 100% in HG/INV lesions and 50% in LG lesions of HG/INV and LG cases. There was no significant difference in mutation frequency in LG lesions between HG/INV and LG cases. These results suggest that RNF43 mutations may be involved in and predictive of malignant transformation from an early stage of MCN.

Review of Prognostic Expression Markers for Clear Cell Renal Cell Carcinoma

Context: The number of prognostic markers for clear cell renal cell carcinoma (ccRCC) has been increasing regularly over the last 15 years, without being integrated and compared. Objective: Our goal was to perform a review of prognostic markers for ccRCC to lay the ground for their use in the clinics. Evidence Acquisition: PubMed database was searched to identify RNA and protein markers whose expression level was reported as associated with survival of ccRCC patients. Relevant studies were selected through cross-reading by two readers. Evidence Synthesis: We selected 249 studies reporting an association with prognostic of either single markers or multiple-marker models. Altogether, these studies were based on a total of 341 distinct markers and 13 multiple-marker models. Twenty percent of these markers were involved in four biological pathways altered in ccRCC: cell cycle, angiogenesis, hypoxia, and immune response. The main genes (VHL, PBRM1, BAP1, and SETD2) involved in ccRCC carcinogenesis are not the most relevant for assessing survival. Conclusion: Among single markers, the most validated markers were KI67, BIRC5, TP53, CXCR4, and CA9. Of the multiple-marker models, the most famous model, ClearCode34, has been highly validated on several independent datasets, but its clinical utility has not yet been investigated. Patient Summary: Over the years, the prognosis studies have evolved from single markers to multiple-marker models. Our review highlights the highly validated prognostic markers and multiple-marker models and discusses their clinical utility for better therapeutic care.

Immunohistochemical analysis of beta-catenin expression: a probable prognostic marker and potential therapeutic target in renal cell carcinoma

Background and aims

Renal cell carcinoma (RCC) seems to be the most aggressive type of genitourinary neoplasm. Down regulation of normal beta-catenin expression contributes to development of RCC, reflecting the role of beta-catenin/Wnt signaling pathway in pathogenesis. This study aims to evaluate the significance of beta-catenin expression and its correlation with the prognostic parameters.

Methods

A cross-sectional observational study was carried out in a tertiary care center on 58 RCC cases using variables like histological grade and type, tumor stage, necrosis. Formalin fixed, paraffin-embedded blocks were evaluated for beta-catenin expression by immunohistochemistry using scoring system. Data were analyzed by mean ± SD, χ² test, Pearson’s correlation test.

Results

Membranous score (MS) had a strong negative correlation with tumor stage (r=−0.407, p=0.044) and grade (r=−0.787, p=<0.001). Mean membranous score difference between low (Stage 1 and 2) vs. high stage (Stage 3 and 4) and low (Grade 1 and 2) vs. high grade (Grade 3 and 4) was statistically significant (p<0.001). Cytoplasmic score (CS) had positive correlation with tumor stage (r=0.586; p=0.002). No significant correlation was evident between cytoplasmic scores and tumor grade, however the mean cytoplasmic score difference between low grade vs. high grade was statistically significant (p < 0.001).

Conclusion

Beta-catenin may play a crucial role in the pathogenesis of RCC and has a positive correlation with the biological behavior of this tumor. The important role of beta-catenin as a prognostic parameter and probably a critical evaluator of targeted chemotherapy cannot be overemphasized.

Inhibition of GSK3 Represses the Expression of Retinoic Acid Synthetic Enzyme ALDH1A2 via Wnt/β-Catenin Signaling in WiT49 Cells

Organogenesis, including renal development, requires an appropriate retinoic acid concentration, which is established by differential expression of aldehyde dehydrogenase 1 family member A2 (ALDH1A2) and cytochrome P450 family 26 subfamily A/B/C member 1 (CYP26A1/B1/C1). In the fetal kidney, ALDH1A2 expresses in the developing stroma and renal vesicle and its derivatives but does not present in the ureteric bud. It remains unclear what may contribute to this expression pattern. Here we show that the glycogen synthase kinase 3 alpha/beta (GSK3A/B) inhibitor CHIR99021 significantly represses ALDH1A2 expression in WiT49, which is a Wilms’ tumor cell line that exhibits “triphasic” differential potential and is used as a fetal kidney cell model. CHIR99021 fails to suppress ALDH1A2 as β-catenin is inhibited, suggesting that the downregulation of ALDH1A2 by CHIR99021 is through Wnt/β-catenin signaling. Ectopic expression of mouse Wnt1, Wnt3a, Wnt4, and Wnt9b represses ALDH1A2 expression in WiT49 cells. Using immunohistochemistry, we show an inverse correlation of Aldh1a2 expression with β-catenin in rat E18.5 kidney. ChIP demonstrated that β-catenin is recruited to the ALDH1A2 promoter, the conserved intron1G, and another site within intron 1 of ALDH1A2. Using a luciferase assay, we further show that the ALDH1A2 promoter and the intron1G element are involved in the repression of ALDH1A2 expression by CHIR99021. Our work demonstrates that ALDH1A2 expression can be directly repressed by the Wnt/β-catenin signaling in fetal kidney cells, suggesting that Wnt/β-catenin may play a role in maintaining the expression pattern of ALDH1A2 in the fetal kidney, thus controlling the availability and localization of retinoic acid and regulating aspects of kidney development.

Comprehensive Immunoprofiles of Renal Cell Carcinoma Subtypes

In recent years, renal epithelial tumors have been among the fastest reclassifying tumors, requiring updates to the tumor classification system. Nonetheless, immunohistochemistry (IHC) remains the most widely used tool for renal epithelial tumors. In this proposal, we aimed to create the most efficient IHC panel for categorizing the diverse subtypes of renal tumors, and to find out more specific immunohistochemical results in each subtype or each antibody. A total of 214 renal tumors were analyzed using 10 possible IHC markers to differentiate subtypes, including three major renal cell carcinoma (RCC) subtypes, clear-cell type (50 cases), papillary type (50 cases), and chromophobe type (20 cases), and minor subtypes (MiT RCC, 13 cases; collecting duct carcinoma, 5 cases; and oncocytoma, 10 cases). A triple immunomarker (cytokeratin 7 (CK7)-carbonic anhydrase IX (CAIX)- alpha-methylacyl-CoA racemase (AMACR)) panel is useful in particular high-grade clear-cell tumors. If IHC remains ambiguous, the use of an adjunctive panel can be suggested, including CD10, epithelial membrane antigen, cathepsin K, c-kit, hepatocyte nuclear factor 1-β, and E-cadherin. For an efficient immunohistochemical strategy for subtyping of RCC, we conclude that the CK7-CAIX-AMACR panel is the best primary choice for screening subtyping.

Recurrent Mutations in APC and CTNNB1 and Activated Wnt/β-catenin Signaling in Intraductal Papillary Neoplasms of the Bile Duct: A Whole Exome Sequencing Study

This study aimed to elucidate the genetic landscape of biliary papillary neoplasms. Of 28 cases examined, 7 underwent whole exome sequencing, while the remaining 21 were used for validation studies with targeted sequencing. In the whole exome sequencing study, 4/7 cases had mutations in either APC or CTNNB1, both of which belong to the Wnt/β-catenin pathway. Somatic mutations were also identified in genes involved in RAS signaling (KRAS, BRAF), a cell cycle regulator (CDC27), histone methyltransferase (KMT2C, KMT2D), and DNA mismatch repair (MSH3, MSH6, PMS1). Combined with discovery and validation cohorts, mutations in APC or CTNNB1 were observed in 6/28 subjects (21%) and were mutually exclusive. When the cases were classified into intraductal papillary neoplasms of the bile duct (IPNBs, n=14) and papillary cholangiocarcinomas (n=14) based on the recently proposed classification criteria, mutations in APC and CTNNB1 appeared to be entirely restricted to IPNBs with 6/14 cases (43%) harboring mutations in either gene. These genetic alterations were detected across the 3 nonintestinal histologic types. In immunohistochemistry, the aberrant cytoplasmic and/or nuclear expression of β-catenin was found in not only 5/6 IPNBs with APC or CTNNB1 mutations, but also 6/8 cases with wild-type APC and CTNNB1 (total 79%). In addition, APC and CTNNB1 alterations were exceptional in nonpapillary cholangiocarcinomas (n=29) with a single case harboring CTNNB1 mutation (3%). This study demonstrated recurrent mutations in APC and CTNNB1 in nonintestinal-type IPNBs, suggesting that activation of the Wnt/β-catenin signaling pathway is relevant to the development and progression of IPNBs.

Nuclear β-catenin localization and mutation of the CTNNB1 gene: a context-dependent association

Although the majority of low-grade, early-stage endometrial cancer patients have good survival with surgery alone, patients who recur tend to do poorly. Identification of patients at high risk of recurrence who would benefit from adjuvant treatment or more extensive surgical staging would help optimize individualized care of endometrial cancer patients. CTNNB1 (encodes β-catenin) mutations identify a subset of low-grade, early-stage endometrial cancer patients at high risk of recurrence. Mutation of CTNNB1 exon 3 is classically associated with translocation of the β-catenin protein from the membrane to the nucleus and activation of Wnt/β-catenin signaling. Given the clinical utility of identifying endometrial carcinomas with CTNNB1 mutation, the purpose of this study was to determine if immunohistochemistry could act as a surrogate for CTNNB1 gene sequencing. Next-generation sequencing was performed on 345 endometrial carcinomas. Immunohistochemical localization of β-catenin was determined for 53/63 CTNNB1 exon 3 mutant tumors for which tissue was available and a subset of wild-type tumors. Nuclear localization of β-catenin had 100% specificity in distinguishing CTNNB1 mutant from wild type, but sensitivity was lower (84.9%). Nearly half of CTNNB1 mutant cases had only 5-10% of tumor cells with β-catenin nuclear localization. The concordance between pathologists blinded to mutation status in assessing nuclear localization was 100%. The extent of β-catenin nuclear localization was not associated with specific CTNNB1 gene mutation, tumor grade, presence of non-endometrioid component, or specific concurrent gene mutations in the tumor. For comparison, nuclear localization of β-catenin was more diffuse in desmoid fibromatosis, a tumor also associated with CTNNB1 mutation. Thus, nuclear localization of β-catenin assessed by immunohistochemistry does not detect all endometrial cancers with CTNNB1 gene mutation. The extent of nuclear localization may be tumor type dependent. For endometrial cancer, immunohistochemistry could be an initial screen, with CTNNB1 sequencing employed when nuclear localization of β-catenin is absent.