Purpose: To examine protein expression characteristics of Distal-less homeobox4 (DLX4) in inflammatory breast cancer (IBC) cases from an African-American population to determine if a) DLX4 over-expression occurs in IBC vs. normal mammary tissue and b) over-expression is associated with clinico-pathologic features such as ER, PR, HER2.

Experimental Design: Twenty nine blocks of formalin-fixed paraffin-embedded (FFPE) tissues from well-characterized human IBC cases were used for immuno-histochemical staining (IHC). Tumor tissues were from African American subjects seen at Howard University Hospital. Normal breast tissues from 30 mammoplasties were controls. IHC results were assigned intensity and percentage scores based upon intensity of positive staining and % of stained cells. Percentage scores were assigned as 0, 1 (0%-25%), 2 (26%-50%), 3 (51%-75%) or 4 (76%-100%) and intensity scores were assigned 0, 1+, 2+ or 3+. For the analysis of the IHC, a percentage score of 3 or 4 was considered high and an intensity score of 2+ or 3+ was categorized as high. Chi-square and Fisher’s exact tests were used for analysis.

Results: The staining pattern for the categorized cohort in which 82.8% (24 out of 29) of IBC cases showed high percentages of positive cells staining for DLX4 protein, while 40.0% (12 out of 30) normal breast tissues demonstrated DLX4 expression (P=0.001). In terms of staining intensity, 75.9% (22 out of 29) of IBC cases showed a high level of intensity, compared to 20.0% (6 out of 30) of normal breast tissues (P<0.001). In terms of the association between breast cancer characteristics and IHC staining, intensity of DLX4 was higher in HER2- (87.0%, 20 out of 23) than HER2+ (33.3%, 2 out of 6; P=0.018). Other associations were not statistically significant in this pilot study.

Conclusions: DLX4 expression is significantly higher in this pilot study of IBC cases from AA patients than in normal breast tissue cases. In addition, HER2- is associated with high intensity of DLX4 expression in IBC.

Associations DLX4 protein expression (IHC) In IBC and normal breast tissues

 Low High P-value 
Percent positivity n (%) n (%)  
Controls (n=30) 18 (60.0) 12 (40.0) 0.001 
IBCs (n=29) 5 (17.2) 24 (82.8)  
Staining intensity n (%) n (%)  
Controls (n=30) 24 (80.0) 6 (20.0) <0.001 
IBCs (n=29) 7 (24.1) 22 (75.9)  
 Low High P-value 
Percent positivity n (%) n (%)  
Controls (n=30) 18 (60.0) 12 (40.0) 0.001 
IBCs (n=29) 5 (17.2) 24 (82.8)  
Staining intensity n (%) n (%)  
Controls (n=30) 24 (80.0) 6 (20.0) <0.001 
IBCs (n=29) 7 (24.1) 22 (75.9)  
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Citation Format: Jaehong Jeong, Tammey Naab, Martin Ongkeko, Kepher Makambi, Farhan A. Khan, Jan Blancato. Signficant DLX4 expression in inflammatory breast cancer tumors from African American patients [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 737. doi:10.1158/1538-7445.AM2017-737

©2017 American Association for Cancer Research.
2017
American Association for Cancer Research.