Li Xiaoxian, Lewis Michael T, Huang Jian, Gutierrez Carolina, Osborne C Kent, Wu Meng-Fen, Hilsenbeck Susan G, Pavlick Anne, Zhang Xiaomei, Chamness Gary C, Wong Helen, Rosen Jeffrey, Chang Jenny C
Breast Center at Baylor College of Medicine, 1 Baylor Plaza BCM 600, TX 77030, USA.
J Natl Cancer Inst. 2008 May 7;100(9):672-9. doi: 10.1093/jnci/djn123. Epub 2008 Apr 29.
Tumorigenic breast cancer cells that express high levels of CD44 and low or undetectable levels of CD24 (CD44(>)/CD24(>/low)) may be resistant to chemotherapy and therefore responsible for cancer relapse. These tumorigenic cancer cells can be isolated from breast cancer biopsies and propagated as mammospheres in vitro. In this study, we aimed to test directly in human breast cancers the effect of conventional chemotherapy or lapatinib (an epidermal growth factor receptor [EGFR]/HER2 pathway inhibitor) on this tumorigenic CD44(>) and CD24(>/low) cell population.
Paired breast cancer core biopsies were obtained from patients with primary breast cancer before and after 12 weeks of treatment with neoadjuvant chemotherapy (n = 31) or, for patients with HER2-positive tumors, before and after 6 weeks of treatment with the EGFR/HER2 inhibitor lapatinib (n = 21). Single-cell suspensions established from these biopsies were stained with antibodies against CD24, CD44, and lineage markers and analyzed by flow cytometry. The potential of cells from biopsy samples taken before and after treatment to form mammospheres in culture was compared. All statistical tests were two-sided.
Chemotherapy treatment increased the percentage of CD44(>)/CD24(>/low) cells (mean at baseline vs 12 weeks, 4.7%, 95% confidence interval [CI] = 3.5% to 5.9%, vs 13.6%, 95% CI = 10.9% to 16.3%; P < .001) and increased mammosphere formation efficiency (MSFE) (mean at baseline vs 12 weeks, 13.3%, 95% CI = 6.0% to 20.6%, vs 53.2%, 95% CI = 42.4% to 64.0%; P < .001). Conversely, lapatinib treatment of patients with HER2-positive tumors led to a non-statistically significant decrease in the percentage of CD44(>)/CD24(>/low) cells (mean at baseline vs 6 weeks, 10.0%, 95% CI = 7.2% to 12.8%, vs 7.5%, 95% CI = 4.1% to 10.9%) and a statistically non-significant decrease in MSFE (mean at baseline vs 6 weeks, 16.1%, 95% CI = 8.7% to 23.5%, vs 10.8%, 95% CI = 4.0% to 17.6%).
These studies provide clinical evidence for a subpopulation of chemotherapy-resistant breast cancer-initiating cells. Lapatinib did not lead to an increase in these tumorigenic cells, and, in combination with conventional therapy, specific pathway inhibitors may provide a therapeutic strategy for eliminating these cells to decrease recurrence and improve long-term survival.
表达高水平CD44和低水平或无法检测到的CD24（CD44(>)/CD24(>/低)）的致瘤性乳腺癌细胞可能对化疗耐药，因此是癌症复发的原因。这些致瘤性癌细胞可从乳腺癌活检组织中分离出来，并在体外作为乳腺球进行增殖。在本研究中，我们旨在直接在人类乳腺癌中测试传统化疗或拉帕替尼（一种表皮生长因子受体[EGFR]/HER2通路抑制剂）对这种致瘤性CD44(>)和CD24(>/低)细胞群体的影响。
从接受新辅助化疗12周前后的原发性乳腺癌患者中获取配对的乳腺癌核心活检组织（n = 31），或者对于HER2阳性肿瘤患者，从接受EGFR/HER2抑制剂拉帕替尼治疗6周前后获取活检组织（n = 21）。从这些活检组织建立的单细胞悬液用抗CD24、CD44和谱系标志物的抗体进行染色，并通过流式细胞术进行分析。比较治疗前后活检样本中的细胞在培养中形成乳腺球的能力。所有统计检验均为双侧检验。
化疗治疗增加了CD44(>)/CD24(>/低)细胞的百分比（基线时平均值与12周时相比，4.7%，95%置信区间[CI]=3.5%至5.9%，与13.6%，95%CI = 10.9%至16.3%；P <.001），并提高了乳腺球形成效率（MSFE）（基线时平均值与12周时相比，13.3%，95%CI = 6.0%至20.6%，与53.2%，95%CI = 42.4%至64.0%；P <.001）。相反，对HER2阳性肿瘤患者进行拉帕替尼治疗导致CD44(>)/CD24(>/低)细胞百分比无统计学意义的下降（基线时平均值与6周时相比，10.0%，95%CI = 7.2%至12.8%，与7.5%，95%CI = 4.1%至10.9%），以及MSFE无统计学意义的下降（基线时平均值与6周时相比，16.1%，95%CI = 8.7%至23.5%，与10.8%，95%CI = 4.0%至17.6%）。
这些研究为化疗耐药的乳腺癌起始细胞亚群提供了临床证据。拉帕替尼并未导致这些致瘤性细胞增加，并且与传统疗法联合使用时，特定通路抑制剂可能提供一种治疗策略来消除这些细胞，以减少复发并提高长期生存率。
