CD44/CD24 and aldehyde dehydrogenase 1 in estrogen receptor-positive early breast cancer treated with tamoxifen: CD24 positivity is a poor prognosticator

• Published in: Oncotarget Vol. 9; no. 2; pp. 2622 - 2630
• Main Authors: Moon, Yong Wha, An, Hee-Jung, Koo, Ja Seung, Kim, Gun Min, Han, Hyunju, Park, Seho, Kim, Seung Il, Park, Hyung Seok, Kim, Sewha, Kim, Seung Ki, Lee, Seung Ah, Hwang, Sohyun, Son, Gun Woo, Sohn, Joohyuk
• Format: Journal Article
• Language: English
• Published: United States Impact Journals LLC 05.01.2018
• Subjects: Research Paper; breast cancer; CD24; resistance; tamoxifen; estrogen-receptor positive
• ISSN: 1949-2553; 1949-2553
• DOI: 10.18632/oncotarget.23519

CD44 /CD24 or aldehyde dehydrogenase 1 (ALDH1) has been suggested as a potential marker for breast cancer stem cells. In the cohort of 819 patients with resected ER-positive breast cancer, the '5-year relapse group' within 5 years postsurgery during adjuvant tamoxifen treatment and the 'non-relapse group' longer than 9 years postsurgery were defined. Paraffin-embedded tumor tissues were available in 31 patients from 5-year relapse group and 68 from the non-relapse group. CD44/ CD24 and ALDH1 expression was evaluated by immunohistochemical staining. Phenotypes of CD44/CD24 were CD44 /CD24 in one patient (1%), CD44 /CD24 in one patient (1%), CD44 /CD24 in 12 patients (12%), and CD44 /CD24 in 67 patients (68%). Four patients (4%) showed ALDH1-positivity. Due to the rarity of CD44-positivity or ALDH1-positivity, we dichotomized the patients into CD24-positive status (13%, 13/99 patients) and CD24-negative status (87%, 86/99 patients) only based on CD24 status, and only the status of CD24 was further analyzed. CD24-positivity was higher in the 5-year relapse group (32%) than in the non-relapse group (4%). CD24-positivity was associated with negative PR (P=0.026), higher N stage (P=0.029), and higher histologic grade (P=0.034). However, in the multivariate logistic regression adjusted for the known prognostic factors, CD24-positivity was still a significant predictive factor for 5-year relapse (hazard ratio=8.5; P=0.006). Our results indicated that the expression of CD24 was a significant poor prognostic factor in ER-positive early breast cancer treated with adjuvant tamoxifen. CD24 is worth further investigation as a novel biomarker for tamoxifen resistance beyond general aggressiveness of cancer cells.