Clinicopathological and prognostic correlations of HER3 expression and its degradation regulators, NEDD4-1 and NRDP1, in primary breast cancer

Abstract

Background: Human epidermal growth factor receptor HER3 (ErbB3), especially in association with its relative HER2 (ErbB2), is known as a key oncogene in breast tumour biology. Nonetheless, the prognostic relevance of HER3 remains controversial. NEDD4-1 and NRDP1 are signalling molecules closely related to the degradation of HER3 via ubiquitination. NEDD4-1 and NRDP1 have been reported to contribute to HER3-mediated signalling by regulating its localization and cell membrane retention. We studied correlations between HER3, NEDD4-1, and NRDP1 protein expression and their association with tumour histopathological characteristics and clinical outcomes.

Methods: The prevalence of immunohistochemically detectable expression profiles of HER3 (n = 177), NEDD4-1 (n = 145), and NRDP1 (n = 145) proteins was studied in primary breast carcinomas on archival formalin-fixed paraffin-embedded (FFPE) samples. Clinicopathological correlations were determined statistically using Pearson's Chi-Square test. The Kaplan-Meier method, log-rank test (Mantel-Cox), and Cox regression analysis were utilized for survival analysis.

Results: HER3 protein was expressed in breast carcinomas without association with HER2 gene amplification status. Absence or low HER3 expression correlated with clinically aggressive features, such as triple-negative breast cancer (TNBC) phenotype, basal cell origin (cytokeratin 5/14 expression combined with ER negativity), large tumour size, and positive lymph node status. Low total HER3 expression was prognostic for shorter recurrence-free survival time in HER2-amplified breast cancer (p = 0.004, p = 0.020 in univariate and multivariate analyses, respectively). The majority (82.8%) of breast cancers demonstrated NEDD4-1 protein expression - while only a minor proportion (8.3%) of carcinomas expressed NRDP1. NEDD4-1 and NRDP1 expression were not associated with clinical outcomes in HER2-amplified breast cancer, irrespective of adjuvant trastuzumab therapy.

Conclusions: Low HER3 expression is suggested to be a valuable prognostic biomarker to predict recurrence in HER2-amplified breast cancer. Neither NEDD4-1 nor NRDP1 demonstrated relevance in prognostics or in the subclassification of HER2-amplified breast carcinomas.

Keywords: Breast cancer; ErbB3; FLRF; HER3; NEDD4–1; NRDP1; Prognostic biomarker; RNF41; Survival.

Fig. 1

HER3 immunohistochemistry. a Positive control (prostate), b Concurrently high (score 3+) membranous and cytoplasmic HER3 expression (breast carcinoma), c High (score 3+) membranous HER3 expression with negative/low (score 0) cytoplasmic HER3 status, d Negative/low total cellular HER3 staining. Mayer's Hematoxylin used as a counterstain

Fig. 2

NEDD4–1 immunohistochemistry. a Positive control (kidney), b Negative/low NEDD4–1 expression (score 1+, breast carcinoma), c Moderate NEDD4–1 expression (score 2+, breast carcinoma), d High NEDD4–1 expression (score 3+, breast carcinoma). Mayer's Hematoxylin used as a counterstain

Fig. 3

NRDP1 immunohistochemistry. a Positive control (testis, cells in seminiferous ducts), b Positive control (mononuclear blood cells), c Absent NRDP1 expression (breast carcinoma), d Cytoplasmic NRDP1 expression (breast carcinoma), e and f Nuclear NRDP1 expression (breast carcinoma). Mayer's Hematoxylin used as a counterstain

Fig. 4

Kaplan-Meier curves showing RFS in HER2-amplified breast cancer (HER2+ BCA cohort) in relation to expression of a total cellular HER3 (n = 177), b membranous HER3 (n = 177), c cytoplasmic HER3 (n = 177), d NEDD4–1 (n = 145), e nuclear NRDP1 (n = 145), and F. cytoplasmic NRDP1 (n = 145). Log rank (Mantel-Cox) p-values are marked within the curves. p-values < 0.05 were considered statistically significant and were marked with *p<0.05 and **p≤0.01