Biological and clinical significance of PARP1 protein expression in breast cancer.

Poly(ADP-ribose) polymerase-1 (PARP1) is a key facilitator of DNA repair. PARP inhibitors have gained recent attention as promising therapeutic agents for the treatment of solid tumours including breast cancer (BC). However, the biological and clinical significance of PARP1 expression in BC and its role in DNA-damage response (DDR) remain to be defined.

Clinicopathological significance of KU70/KU80, a key DNA damage repair protein in breast cancer.

Although the role of BRCA1 and the homologous recombination (HR) pathway in breast cancer (BC) has been extensively studied, the alternative repair pathway for DNA double-strand breaks (DSBs), non-homologous end-joining (NHEJ) remains to be defined. Ku proteins bind to DNA DSB ends and play a key role in NHEJ. In this study we aimed to assess the expression and biological significance of the KU70/KU80 heterodimer in the different molecular classes of BC.

Prognostic value of proliferation assay in the luminal, HER2-positive, and triple-negative biologic classes of breast cancer.

Introduction: Although the prognostic significance of proliferation in early invasive breast cancer has been recognized for a long time, recent gene-expression profiling studies have reemphasized its biologic and prognostic value and the potential application of its assessment in routine practice, particularly to define prognostic subgroups of luminal/hormone receptor-positive (HR+) tumors. This study aimed to assess the prognostic value of a proliferation assay by using Ki-67 immunohistochemistry as compared with mitotic count scores.

Method: Proliferation was assessed by using Ki-67 labeling index (Ki-67LI) and mitotic scores in a large (n = 1,550) and well-characterized series of clinically annotated primary operable invasive breast cancer with long-term follow-up.

A CD44⁻/CD24⁺ phenotype is a poor prognostic marker in early invasive breast cancer.

A CD44(-)/CD24(+) phenotype is a poor prognostic marker in early invasive breast cancer. Breast cancer cells with high CD44 and low or absent CD24 (i.e.

Clinical and biological significance of E-cadherin protein expression in invasive lobular carcinoma of the breast.

Background: Although virtually all cases of lobular carcinoma in situ lack E-cadherin expression, a proportion of morphologically typical invasive lobular carcinomas (ILCs) retain its expression. The frequency and significance of E-cadherin expression in ILC remain to be elucidated. In this study, we have assessed E-cadherin protein expression in a well-characterized series of histologically defined ILC (239 cases) with a long-term clinical follow-up to determine the frequency, clinical and biological significance of its expression.

CTEN (C-terminal tensin-like), a novel oncogene overexpressed in invasive breast carcinoma of poor prognosis.

C-terminal tensin-like (CTEN) gene is a member of the TENSIN gene family, involved in cell migration and localised at focal adhesion sites. This study was designed to explore the prevalence and clinical significance of CTEN expression in a large and well-characterised series (n = 1,409) invasive breast cancer (BC) cases with long term follow-up (median 11 years), using immuno-histochemistry and tissue microarray. Moderate to strong cytoplasmic immunoreactivity for CTEN was observed in 90% of the studied cases.

Triple-negative breast cancer: distinguishing between basal and nonbasal subtypes.

Purpose: Triple-negative (TN; estrogen receptor, progesterone receptor, and HER-2 negative) cancer and basal-like breast cancer (BLBC) are associated with poor outcome and lack the benefit of targeted therapy. It is widely perceived that BLBC and TN tumors are synonymous and BLBC can be defined using a TN definition without the need for the expression of basal markers.

Experimental Design: We have used two well-defined cohorts of breast cancers with a large panel of biomarkers, BRCA1 mutation status, and follow-up data to compare the clinicopathologic and immunohistochemical features of TN tumors expressing one or more of the specific basal markers (CK5/6, CK17, CK14, and epidermal growth factor receptor; BLBC) with those TN tumors that express none of these markers (TN3BKE-).

C-terminal Tensin-like (CTEN) is an oncogene which alters cell motility possibly through repression of E-cadherin in colorectal cancer.

The Tensin gene family encodes proteins thought to modulate integrin function. C-terminal Tensin-like (CTEN) is a member of the Tensin gene family which lacks the N-terminus actin-binding domain. Cten is reported to have both oncogenic and tumour-suppressor functions.