Background: Although long-term estrogen (E2) exposure is associated with increased breast cancer (BC) risk, and E2 appears to sustain growth of BC cells that express functional estrogen receptors (ERs), its role in promoting BC stem cells (CSCs) remains unclear. Considering that Gli1, part of the Sonic hedgehog (Shh) developmental pathway, has been shown to mediate CSCs, we investigated whether E2 and Gli1 could promote CSCs and epithelial-mesenchymal transition (EMT) in ER⁺ BC cell lines. Methods: We knocked down Gli1 in several BC cells using a doxycycline-controlled vector, and compared Gli1-knockdown cells and Gli1 ⁺ cells in behavior and expression of ER, Gli1, ALDH1 (BC-CSC marker), Shh, Ptch1 (Shh receptor) and SOX2, Nanog and Bmi-1 (CSC-associated transcriptions factors), using PCR; tissue microarrays, western blot; chromatin immunoprecipitation q-PCR, confocal immunofluorescence microscopy; fluorescence-activated cell sorting; annexin–flow cytometry (for apoptosis); mammosphere culture; and colony formation, immunohistochemistry, Matrigel and wound-scratch assays. Results: Both mRNA and protein expressions of ER correlated with those of Gli1 and ALDH1. E2 induced Gli1 expression only in ER⁺ BC cells. E2 promoted CSC renewal, invasiveness and EMT in ER⁺/Gli1⁺ cells but not in Gli1-knockdown cells. Conclusions: Our results indicate that estrogen acts via Gli1 to promote CSC development and EMT in ER⁺ BC cells. These findings also imply that Gli1 mediates cancer stem cells, and thus could be a target of a novel treatment for ER⁺ breast cancer.

Overexpression of P-glycoprotein (P-gp) encoded by MDR1 gene in cancer cells results in multidrug resistance (MDR) to structurally and mechanistically different chemotherapeutic drugs, which is a major cause for cancer chemotherapy failures to cancer patients. Recently, there were several reports showing that expression of siRNAs targeting MDR1 gene is able to reverse the P-gp mediated MDR, however, the in vivo reversal effects for MDR have still not been identified. We developed a novel MDR reversal system using RNA interference technique in human epidermoid carcinoma KBv200 cells. The stably expressing MDR1 shRNA cells (KBv200/MDR1sh) were established with transfection of vector pEGFPC2-H1-MDR1shDNA containing MDR1-V siRNA expression cassette, and we found that more than 90% of MDR1 mRNA and P-gp were reduced. KBv200/MDR1sh cells simultaneously showed stably expressing EGFP and kept low MDR1 expression beyond ten passages. Compared KBv200/MDR1sh cells with KBv200 cells, resistance to vincristine and doxorubicin decreased from 62.4-fold to 10.5-fold and from 74.5-fold to 9.5-fold respectively, and intracellular doxorubicin accumulation enhanced from 0.30 +/- 0.08 nmoles/10(6) cells to 0.86 +/- 0.16 nmoles/10(6) cells, and the fluorescence intensity of intracellular Rhodamine 123 accumulation increased from 3.58 +/- 1.63/10(6) cells to 13.96 +/- 3.07/10(6) cells. In the nude mice xenografts, vincristine (0.2 mg/kg of body weight) inhibited the growth of KBv200/MDR1sh solid tumors by 42.0%, but the same dose of vincristine didn't inhibit the growth of KBv200 solid tumors significantly. These results suggest that administration of RNAi targeted MDR1 gene can effectively reverse MDR both in vitro and in vivo models.

Human peripheral blood monocytes are a heterogeneous population, including CD14⁺CD16^-‘classical’ monocytes and CD14⁺CD16⁺‘proinflammatory’ monocytes. CD16⁺ monocytes are expanded in various inflammatory conditions. However, little is known about the CD14⁺CD16⁺ monocytes in patients with breast cancer. We detected CD14⁺CD16⁺ monocytes in 96 patients with breast cancer and 54 control subjects using flow cytometry. Receiver-operating characteristic (ROC) curve analysis was used to determine the feasibility of CD14⁺CD16⁺ monocytes as an indicator for diagnosis of breast cancer. We found that the frequency of CD14⁺CD16⁺ monocytes showed a significantly greater increase in breast cancer patients than in controls (16·96% versus 10·84%, P < 0·0001). The area under the ROC curve for CD14⁺CD16⁺ monocytes was 0·805 [95% confidence interval (95% CI): 0·714–0·877, P = 0·0001]. Furthermore, the levels of CD16⁺ monocytes were significantly negatively associated with the tumour size and pathological staging. In vitro, we showed that CD14⁺CD16⁺ monocytes were expanded significantly when the purified CD14⁺ monocytes were exposed to Michigan Cancer Foundation (MCF)-7 cells-conditioned medium (MCF-CM) or, separately, to monocyte chemotactic protein 1 (MCP-1). Neutralizing antibodies against MCP-1 inhibited the expansion of CD14⁺CD16⁺ monocytes by MCF-CM. Collectively, our findings indicated that MCP-1 can expand CD14⁺CD16⁺ monocytes in patients with breast cancer. Furthermore, the CD14⁺CD16⁺ monocyte may be a useful indicator in early diagnosis of breast cancer.