Clinical and biological roles of Kelch-like family member 7 in breast cancer: a marker of poor prognosis

Background: The functions of many proteins are tightly regulated with a complex array of cellular functions including ubiquitination. In cancer cells, aberrant ubiquitination may promote the activity of oncogenic pathways with subsequent tumour progression. Kelch-like family member 7 (KLHL7) is involved in the regulation of ubiquitination and may play a role in breast cancer (BC). Present study aims to evaluate the biological and clinical usefulness of KLHL7 in BC utilising large well-characterised cohorts with long-term follow-up. Methods: The relationships between KLHL7 gene copy number alteration (CNA) and mRNA expression and clinicopathological variables and clinical outcomes were evaluated in 1980 patients from the METABRIC BC cohort. Prognostic signifcance of KLHL7 mRNA was validated using the Breast Cancer Gene-Expression Miner v4.0 datasets (n=5206). KLHL7 protein expression was assessed using immunohistochemistry in a large annotated series of early-stage BC (n=917) with long-term follow-up. Results: KLHL7 CNA was signifcantly correlated with its mRNA expression. KLHL7 mRNA expression was higher in luminal B and basal-like molecular subtypes and in higher grade tumours. Increased KLHL7 protein expression was signifcantly correlated with features of aggressive phenotype including lymphovascular invasion, high histological grade, hormonal receptor negativity, high PIK3CA and p53 expression. Outcome analysis showed that high KLHL7 expression is an independent predictor of shorter survival (p=0.0011). Conclusions: KLHL7 appears to play an important role in BC progression. High KLHL7 protein expression identifed a subgroup of BC with aggressive behaviour and provided independent prognostic information

Homozygous Mutations in the 5 ' Region of the JUP Gene Result in Cutaneous Disease but Normal Heart Development in Children

Desmosomes are intercellular adhesive junctions and attachment sites for the intermediate filament (IF) cytoskeleton, prominent in tissues subject to high levels of mechanical stress such as the epidermis and heart. The obligate desmosomal constituent, plakoglobin (PG), is involved in coupling transmembrane desmosomal components with IFs. PG also contributes to intercellular adhesion through adherens junctions and has additional signaling roles. To date, two mutations in the gene encoding PG, JUP, have been described, and in both instances, patients harboring pathogenic mutations suffered from arrhythmogenic right ventricular cardiomyopathy with or without skin abnormalities. We describe homozygous nonsense mutation, p.S24X, and homozygous splice site mutation, c.468G&gt;A, in the JUP gene that results in skin fragility, diffuse palmoplantar keratoderma, and woolly hair with no symptoms of cardiomyopathy. We show barely detectable levels of PG immunostaining in skin sections from patients harboring these mutations and show that an alternative AUG codon in p.S24X mRNA translates a 42-amino-acid N-terminal truncation. We conclude that PG is required for correct maintenance of skin integrity, and the absence of heart phenotype in patients suggests that aberrant PG expression does not compromise normal human heart development in children. Our findings provide new insight into the distinct roles that PG has in the epidermis and heart.</p