GRB7 Expression and Correlation With HER2 Amplification in Invasive Breast Carcinoma

Area of Science:

• Oncology
• Molecular Biology
• Genetics

Background:

• Growth factor receptor-bound protein 7 (GRB7) is located near the HER2 gene on chromosome 17q12-21.
• GRB7 is often coamplified with HER2 in breast cancer and may contribute to therapy resistance.

Purpose of the Study:

• To investigate the correlation between GRB7 expression and HER2 status in invasive breast cancer.
• To examine the association of GRB7 with other prognostic and predictive factors like ER, PR, p53, histologic grade, and pathologic stage.

Main Methods:

• Immunohistochemistry was used to evaluate GRB7 expression in 188 invasive breast carcinoma samples.
• Samples were categorized based on HER2 overexpression, HER2 gene amplification, and chromosome 17 copy number.
• p53 immunohistochemistry was performed on a subset of cases.

Main Results:

• GRB7 expression strongly correlated with HER2 overexpression (33.33% in HER2+ vs. 1.03% in HER2- cases, P<0.0001).
• GRB7 positivity was associated with a higher degree of HER2 amplification (mean copy number 21.14 vs. 9.8, P=0.0001).
• GRB7 expression significantly correlated with ER negativity (P=0.012) and p53 positivity (P=0.03).

Conclusions:

• GRB7 expression in invasive breast cancer is associated with markers of a more aggressive phenotype.
• These markers include HER2 overexpression, increased HER2 amplification, ER negativity, and p53 positivity.
• GRB7 may play a role in the progression and treatment resistance of certain breast cancers.