Tamoxifen-resistant breast cancer cells possess cancer stem-like cell properties / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Cancer stem cells (CSCs) are the cause of cancer recurrence because they are resistant to conventional therapy and contribute to cancer growth and metastasis. Endocrinotherapy is the most common breast cancer therapy and acquired tamoxifen (TAM) resistance is the main reason for endocrinotherapy failure during such therapy. Although acquired resistance to endocrine treatment has been extensively studied, the underlying mechanisms are unclear. We hypothesized that breast CSCs played an important role in TAM-induced resistance during breast cancer therapy. Therefore, we investigated the biological characteristics of TAM-resistant (TAM-R) breast cancer cells.</p><p><b>METHODS</b>Mammosphere formation and tumorigenicity of wild-type (WT) and TAM-R MCF7 cells were tested by a mammosphere assay and mouse tumor xenografts respectively. Stem-cell markers (SOX-2, OCT-4, and CD133) and epithelial-mesenchymal transition (EMT) markers were tested by quantitative real-time (qRT)-PCR. Morphological observation was performed to characterize EMT.</p><p><b>RESULTS</b>After induction of TAM resistance, TAM-R MCF7 cells exhibited increased proliferation in the presence of TAM compared to that of WT MCF7 cells (P < 0.05), indicating enhanced TAM resistance of TAM-R MCF7 cells compared to that of WT MCF7 cells. TAM-R MCF7 cells showed enhanced mammosphere formation and tumorigenicity in nude mice compared to that of WT MCF7 cells (P < 0.01), demonstrating the elevated CSC properties of TAM-R MCF7 cells. Consistently, qRT-PCR revealed that TAM-R MCF7 cells expressed increased mRNA levels of stem cell markers including SOX-2, OCT-4, and CD133, compared to those of WT MCF7 cells (P < 0.05). Morphologically, TAM-R MCF7 cells showed a fibroblastic phenotype, but WT MCF7 cells were epithelial-like. After induction of TAM resistance, qRT-PCR indicated that MCF7 cells expressed increased mRNA levels of Snail, vimentin, and N-cadherin and decreased levels of E-cadherin, which are considered as EMT characteristics (P < 0.05).</p><p><b>CONCLUSION</b>TAM-R MCF7 cells possess CSC characteristics and may be responsible for TAM resistance during breast cancer therapy.</p>

High risk factors of brain metastases in 295 patients with advanced breast cancer / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>The incidence of brain metastases in patients with breast cancer is approximately 10% - 16%, and survival after diagnosis of brain metastases is usually short. This study was designed to evaluate the risk factors associated with brain metastases in advanced breast cancer patients, with a view to help predict patient groups with high risk of brain metastases.</p><p><b>METHODS</b>In total, 295 patients with advanced breast cancer were evaluated. All patients were pathologically confirmed and metastatic lesions were confirmed pathologically or by imaging. All patients were examined at least once every 6 months with head CT or MRI. Patients showing symptoms underwent immediate inspection, and brain metastatic lesions were confirmed by head CT and/or MRI.</p><p><b>RESULTS</b>At a median follow-up of 12 months from the occurrence of metastases, brain metastases had occurred in 49 patients (16.6%). In our univariate analysis, variables significantly related to increased risk of brain metastases were hormone receptor-negative tumors, epidermal growth factor receptor 2 (HER2)-positive tumors, and multiple distant metastases. Patients with dominant tumor sites in soft tissue, or defined as Luminal A subtype, tended to have a lower risk of brain metastases than patients with visceral metastases, Luminal B subtype, triple-negative subtype or HER2-enriched subtype tumors.</p><p><b>CONCLUSIONS</b>Our results strongly suggest that factors such as Luminal B, triple-negative, and HER2-enriched subtypes are high risk factors for brain metastases. These data, therefore, provide pivotal clinical evidence towards a comprehensive understanding of the risk factors of brain metastases in advanced breast cancer patients.</p>

Predictive value of (99)Tc(m)-MIBI scintimammography in evaluation of the efficacy of neoadjuvant chemotherapy in patients with operable breast cancer / 中华肿瘤杂志

<p><b>OBJECTIVE</b>To investigate the value of technetium-99m methoxyisobutylisonitrile ((99)Tc(m)-MIBI) imaging in predicting the efficacy of neoadjuvant chemotherapy (NCT) and prognosis in patients with operable breast cancer.</p><p><b>METHODS</b>Sixty five patients with breast cancer underwent (99)Tc(m)-MIBI scintimammography before NCT, and static planar images were taken at 10 min and 180 min after scintimammography. The clearance rate was calculated in each patient, correlation between the clearance rate and efficacy of NCT, and the disease free survival rate were analyzed.</p><p><b>RESULTS</b>The mean clearance rate of 65 patients was (17.4 ± 6.8)%. The efficacy of NCT was 86.2% (CR 4 cases, PR 52 cases, SD 8 cases, and PD 1 case), and the mean clearance rate of patients with good response or poor response of chemotherapy were (15.5 ± 5.0)% and (29.2 ± 3.2)%, respectively. There was a significant difference between the two groups. The average disease free survival rate in the group with low clearance rate was (75.8%, P = 0.046), significantly higher than that in the group with high clearance rate (53.1%).</p><p><b>CONCLUSION</b>Scintimammography of (99)Tc(m)-MIBI may be used to evaluate the efficacy and prognosis of NCT for patients with operable breast cancer.</p>

Enrichment of breast cancer stem cells using a keratinocyte serum-free medium / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Keratinocyte serum-free medium (K-SFM) is a defined medium used to support the growth of primary keratinocytes and embryonic stem cell. The aim of this research was to optimize enrichment of breast cancer stem cells (CSCs) using K-SFM.</p><p><b>METHODS</b>A K-SFM was used to enrich CSCs from two breast cancer cell lines and a primary culture of breast cancer. RPMI-1640 supplemented with 10% fetal calf serum (FCS) was used as a control. CSCs were identified with flow cytometry using CD44(+)/CD24(-) as molecular markers. The expression of a variety of CSC markers (Oct-4, ABCG2, Nanog, N-cadherin, and E-cadherin) was analyzed with real-time PCR.</p><p><b>RESULTS</b>Much higher percentage of CSCs was achieved with K-SFM: 17.3% for MCF-7 cells, 17.4% for SKBR-3, and 20.0% for primary breast cancer culture. Less than 1% CSC was achieved using RPMI-1640 supplemented with 10% FCS. In comparison to the CSCs obtained with RPMI-1640, CSCs in the K-SFM expressed higher levels of Oct-4, ABCG2, Nanog and N-cadherin, and lower level of E-cadherin.</p><p><b>CONCLUSION</b>K-SFM is an optimal culture medium to maintain and to enrich breast CSCs.</p>

The relationship between 99mTc-MIBI scintimammography of breast cancer and multidrug-resistant proteins / 中华肿瘤杂志

<p><b>OBJECTIVE</b>To evaluate the relationship between the clearance rate of technetium-99m methoxyisobutylisonitrile ((99m)Tc-MIBI) in scintimammography and multidrug-resistant proteins expression in breast cancer tissues.</p><p><b>METHODS</b>Seventy-six patients with breast cancer underwent (99m)Tc-MIBI scintimammography before treatment, and static planar images were taken at 10 min and 180 min after scintimammography. The clearance rate of (99m)Tc-MIBI was calculated in each patient. Immunohistochemical analysis was performed on pathological specimens of the 76 breast tumors to determine the expression of P-glycoprotein (P-gp), glutathione S-transferase Pi (GST-pi) and topoisomerase II (Topo II).</p><p><b>RESULTS</b>The clearance rate was significantly higher in 36 patients with positive P-gp expression when compared with that in 40 patients with negative P-gp expression. There was no significant relationship between GST-pi, Topo II and the clearance rate of (99m)Tc-MIBI.</p><p><b>CONCLUSION</b>The clearance rate of (99m)Tc-MIBI in breast imaging may be used to evaluate the P-gp level in breast cancers.</p>