ZNF703 gene copy number and protein expression in breast cancer; associations with proliferation, prognosis and luminal subtypes.

PURPOSE: Amplification of 8p12 is frequent in breast cancer and associated with poor prognosis in luminal subtypes. ZNF703 has been identified as the driver gene of proliferation in the A1 amplicon situated in 8p12. In this study, the aims were to investigate associations between ZNF703 copy number alterations and molecular subtypes, proliferation and prognosis, and using immunohistochemistry, examine associations between ZNF703 copy number and ZNF703 protein expression. METHODS: Copy number alterations in 702 primary breast tumours and corresponding lymph node metastases were examined using fluorescence in situ hybridization with probes for ZNF703 and centromere 8. In addition, protein expression was studied in 869 tumours from the same cohort. Associations between copy number alterations and protein expression and tumour characteristics were assessed using Pearson chi square test. The prognostic impact of ZNF703 copy number increase and protein expression was assessed estimating cumulative incidence of breast cancer death and hazard ratios. RESULTS: We found mean ZNF703 copy number ≥ 6 in 7% of tumours, most frequently in Luminal B subtypes. We found a positive association between increased copy number, and high proliferation, high histological grade, and poor prognosis. Luminal A tumours with high copy number had high histological grade and poor prognosis (borderline significant). We found positive nuclear staining in 76% of primary tumours. There was an association between copy number status and protein expression, but no association between protein expression and prognosis. CONCLUSIONS: In breast cancer, high ZNF703 copy number is associated with increased proliferation, Luminal B subtypes and poor prognosis.

The prognostic value of androgen receptors in breast cancer subtypes.

PURPOSE: Androgen receptor (AR) expression is frequent in breast cancer and has been associated with good prognosis in several studies. The present study investigates AR-expression in relation to molecular subtypes, clinicopathological features and prognosis in 1297 primary tumours and 336 paired axillary lymph node metastases (LNM) from two cohorts of Norwegian patients. METHODS: Immunohistochemistry for AR was performed on tumours previously reclassified into molecular subtypes using immunohistochemistry and in situ hybridisation. Associations between AR-expression and clinical features were studied using Chi-square tests. Cumulative incidence of breast cancer death and Cox regression analyses were used to assess prognosis. RESULTS: AR-positivity was found in 78.0% of all cases, 84.9% of luminal and 45.1% of non-luminal tumours. The highest proportion of AR-positivity was found in Luminal B tumours, and the lowest in the Basal phenotype. Discordance in AR-status between primary tumours and lymph node metastases was observed in 21.4% of cases. A switch from AR- primary tumour to AR+ lymph node metastasis was seen in 60/72 discrepant cases. AR-expression in primary tumours was an independent and favourable prognostic marker (HR 0.70, 95% CI 0.55-0.90), particularly in the Luminal A subtype, and in grade 3 tumours. CONCLUSIONS: AR is an independent predictor of good prognosis in BC, particularly in grade 3 and Luminal A tumours. Discordant AR-expression between primary tumour and LNM was observed in 21.4% of cases and most often there was a switch from AR- primary tumour to AR+ axillary LNM.