The forkhead box M1 (FOXM1) transcription factor regulates the expression of genes essential for cell proliferation and transformation and is implicated in tumorigenesis and tumor progression. FOXM1 has been considered as a potential target for the prevention and/or therapeutic intervention in human carcinomas. In this study, we observed a strong expression of FOXM1 in clinical tissue specimens and cell lines of human breast cancer and a correlation between FOXM1 levels and the proliferation ability in the tested MCF-7, MDA-MB-231 and ZR-75-30 cells. By using an adenovirus vector (named AdFOXM1shRNA) that expresses a short hairpin RNA (shRNA) to downregulate FOXM1 expression specifically, we found that the knockdown of FOXM1 expression diminished the proliferation and anchorage-independent growth of the breast cancer cells. The FOXM1 silencing in ZR-75-30 cells dramatically prevented the tumorigenicity of the AdFOXM1shRNA-treated cells in vitro and in vivo. Furthermore, the efficacy of AdFOXM1shRNA for tumor gene therapy was assessed with the breast cancer xenograft mouse model and the tumor growth was significantly suppressed when inoculated mice were injected with AdFOXM1shRNA in the tumors. Together, our results suggest that FOXM1 is a potential therapeutic target for breast cancer and AdFOXM1shRNA may be an additional gene therapeutic intervention for breast cancer treatment.
Breast cancer is an important cause of mortality among women and remains a public-health issue on a global scale.1 According to the assessment of breast cancer data during the period of 1980–2010 in 187 countries, the global breast cancer incidence increases by an annual rate of 3.1%, from 641 000 cases in 1980 to 1 643 000 cases in 2010, and there are 425 000 deaths caused by breast cancer in 2010.1 Breast cancer is commonly treated by various combinations of surgery, radiation therapy, chemotherapy and hormone therapy, and the selection of therapy is influenced by the clinical and pathology features based on conventional histology, immunohistochemistry and molecular profiling of the cancer.2, 3, 4 Combinatorial therapies that use novel agents targeting growth factor receptors, signal transduction pathways and tumor angiogenesis are investigated in clinical trials.5
Transcription factor forkhead box M1 (FOXM1) belongs to the forkhead/winged-helix family of transcription factors6 and is ubiquitously expressed in proliferating and regenerating mammalian cells.7, 8 FOXM1 is a key cell cycle regulator of both the transition from G1 to S phase and the progression to mitosis by regulating transcription of cell cycle genes.9, 10, 11, 12, 13, 14, 15 Loss of FOXM1 expression causes diminished DNA replication, mitotic spindle defects and mitotic catastrophe.13, 14, 16 Furthermore, along with others, we have shown that FOXM1 is involved in conteracting stresses induced by cytotoxic or genotoxic signals, such as oxidative stress or DNA damage.17, 18, 19 Moreover, we have characterized that FOXM1 has an essential role in maintenance of stem cell pluripotency and its expression is absent from differentiated cells.20 These observations suggest that altered expression of FOXM1 is associated with tumorigenesis through its critical roles in cell proliferation, prevention of differentiation and malignant transformation of undifferentiated cells. This notion is apparently supported by the fact that FOXM1 is highly expressed in various types of human malignancies, such as lung cancer,21 glioblastomas,22 prostate cancer,23 basal cell carcinomas,24 hepatocellular carcinoma,15 pancreatic cancer,25 gastric cancer26 and squamous cell carcinoma.27 The inactivation of FOXM1 leads to inhibition of progression and/or invasion of these cancers, suggesting that FOXM1 appears to be an attractive target for the development of novel anticancer therapies.28, 29, 30
Elevated expression or activity of FOXM1 is associated with the development and progression of breast cancer. It was found that FOXM1 was overexpressed in breast cancer in comparison with normal breast tissue both on the RNA and protein level.31 FOXM1 was one of the markers that might allow early detection of both the ductal carcinoma in situ and invasive ductal carcinoma of the mammary gland.32 Interestingly, there was a strong and significant positive correlation between ERalpha and FOXM1, and FOXM1 was shown to stimulate the transcription of ERalpha in breast cancer cells.33 On the other hand, the expression of FOXM1 could be regulated by ERalpha and/or ERbeta.34, 35 Furthermore, there was a significant correlation between FOXM1 expression and the HER2 status31 and FOXM1 was a downstream target and marker of HER2 overexpression in breast cancer,36 pointing to a potential role of FOXM1 as a new drug target in HER2-resistant breast cancer. As the depletion of FOXM1 limits proliferation of breast cancer cells, inhibiting FOXM1 represents a therapeutic strategy to target breast cancer.
In this study, we observed strong expression of FOXM1 in clinical tissue specimens and cell lines of human breast cancer. We found that the downregulation of FOXM1 expression inhibited the breast cancer cell proliferation. To develop innovative strategies for breast cancer gene therapy, we developed an efficient adenovirus-mediated short hairpin RNA (shRNA) expression system to specifically knockdown FOXM1 expression in breast cancer cells. Using this system, we investigated the function of FOXM1 in breast cancer tumorigenesis and evaluated the potential of FOXM1 as a therapeutic target for breast cancer treatment.
Materials and methods
The human breast cancer cell lines MCF-7, MDA-MB-231 and ZR-75-30 were purchased from the Cell Bank of Chinese Academy of Sciences (Shanghai, China) and maintained according to ATCC (Manassas, VA) instructions. Adenovirus-purification 293A (Invitrogen, Grand Island, NY) were cultured in Dulbecco’s modified Eagle’s medium (Invitrogen) containing 10% fetal bovine serum (Invitrogen) and 1% penicillin streptomycin (Invitrogen). All cells were cultured in a 5% CO2-humidified atmosphere at 37 °C.
Human breast ductal tumor paraffin sections were obtained from the Department of Pathology, Hunan Provincial Tumor Hospital, Hunan, China. The slides of samples of patients and nude mouse xenograft tumors were stained with a mouse anti-FOXM1 antibody (1:100; Abcam, Cambridge, UK; ab55006), followed by the incubation of a horseradish peroxidase-conjugated anti-mouse secondary antibody. Color was detected with 3,3'-diaminobenzidine and pictures were taken at × 200 magnification using a TE2000 microscope (Nikon, Tokyo, Japan).
Western blot assay
The lysates of clinical tumor tissues or breast cancer cell lines were separated using sodium dodecyl sulfate-polyacrylamide gel electrophoresis and transferred onto polyvinylidene difluoride membrane for western blotting as described earlier.19 The following antibodies and dilutions were used for western blotting: rabbit anti-FOXM1 (1:1000; Abcam ab47808), mouse anti-β-actin (1:5000; Beyotime AA128, Beyotime, Shanghai, China). The signals from the primary antibody were amplified by horseradish peroxidase-conjugated anti-rabbit immunoglobulin G (1:10 000; GE, Fairfield, CT LNA934VAE) or anti-mouse immunoglobulin G (1:10 000; GE LNA931VAD), and detected with Enhanced Chemiluminescence Plus (Beyotime).
Isolation RNA, reverse transcription-PCR and quantitative real-time PCR
The total RNA was isolated by Total RNA Kit (Omega, Norcross, GA) according to the manufacturer’s protocols. The complementary DNAs were synthesized with M-MLV Reverse Transcriptase (Invitrogen) from total RNA samples. PCR amplification was performed with Taq DNA polymerase mix (Biotech, Qingdao, China) with following sense (S) and antisense (AS) primers, annealing temperature (Ta) and number of PCR cycles (N): hFOXM1-S, 5′-IndexTermGCTTGCCAGAGTCCTTTTTGC-3′ and hFOXM1-AS, 5′-IndexTermCCACCTGAGTTCTCGTCAATGC-3′ (Ta:56 °C, N:30); hCyclinB1-S, 5′-IndexTermGGTCTGGGTCGGCCTCTACCT-3′ and hCyclinB1-AS, 5′-IndexTermAGCCAGGTGCTGCATAACTGGAA-3′ (Ta:59 °C, N:30); hCENPB-S, 5′-IndexTermATTCAGACAGTGAGGAAGAGGACG-3′ and hCENPB-AS, 5′-IndexTermCATCAATGGGGAAGGAGGTCAG-3′ (Ta:60 °C, N:30); hβ-actin-S, 5′-IndexTermAGCGAGCATCCCCCAAAGTT-3′ and hβ-actin-AS, 5′-IndexTermGGGCACGAAGGCTCATCATT-3′ (Ta:54 °C, N:23). Quantitative real-time PCR was performed with SYBR Green (Roche, Basel, Switzerland) in the realplex2 quantitative real-time PCR system (Eppendorf, Hamburg, Germany).
Adenovirus purification and infection
The AdFOXM1shRNA and control virus (AdLacZ) were preserved in our lab and the large-scale adenovirus purification was performed as described previously.30, 37, 38 Infection was induced by the addition of the virus directly to serum-free medium for 1 h at 37 °C. The viral infection was stopped by replacing with the culture medium and the cells were cultured for additional different time courses.
Flow cytometry analysis
The tested cells were collected and washed twice with phosphate-buffered saline. Cells were fixed in 70% ethanol and collected by centrifugation 3000 r.p.m. for 8 min. The cell pellets were resuspended in propidium iodide (0.05 mg ml−1) plus RNase (0.02 mg ml−1) and incubated in the dark at room temperature for 30 min. The cells were filtered and analyzed for DNA content on Quanta SC flow cytometer (Beckman, Brea, CA).
Soft agar colonization assay
The tested cells were mixed with 1 ml culture medium containing 0.35% (w/v) agar and layered over a basal layer of 0.7% (w/v) agar with culture medium in six-well plates. The cells were allowed to grow for 10–14 days. Experiments were carried out three times and the results are representative of the three independent observations.
Xenograft tumor models in nude mice and ad injection
BalB/c nude mice (female, 4-week old) were purchased from SLAC Laboratory Animal Company (Shanghai, China), China. The mice were maintained under standard conditions according to the institutional guidelines for animal care. To study the effect of FOXM1 silencing on tumor growth in vivo, two separate experiments were performed. In the first experiment, the mice were divided into three groups randomly (four mice per group) and injected in the flank with 3 × 106 ZR-75-30 cells transfected with serum-free medium, AdLacZ or AdFOXM1shRNA (10 plaque-forming unit (p.f.u.) per cell), respectively. In the second experiment, the tumor model in nude mice involved subcutaneous inoculation of 3 × 106 ZR-75-30 cells. Although the tumor volume reached 50–100 mm3, we injected 5 × 108 p.f.u. AdLacZ or AdFOXM1shRNA in two groups, respectively. The infections were repeated three times at 3-day intervals. The tumor volume in each group was measured at certain time points according to the method described earlier.39 All the mice were killed at the end of the procedure and the tumor samples were collected.
We used Microsoft Excel Program to calculate s.d. and statistically significant differences between samples. The asterisks in each graph indicate statistically significant changes with P-values calculated by Student’s T-test: *P<0.05, **P⩽0.01 and ***P⩽0.001. P-values <0.05 were considered statistically significant.
The expression of FOXM1 in clinical tissues and malignant cell lines of breast cancer
The expression of FOXM1 was found to be elevated in clinical samples of primary breast cancer.16, 31, 32, 40 We first confirmed the published findings by measuring the expression levels of FOXM1 with western blotting in the lysates of clinical human breast ductal carcinoma samples, in which 14 out of 16 analyzed cases showed FOXM1 positive (Figure 1a). We immunostained the tissue sections with an anti-FOXM1 antibody and observed positive FOXM1 staining predominantly in the samples of breast ductal carcinoma but not in the normal breast tissues (Figure 1b). By using quantitative real-time PCR analysis, we found that FOXM1 mRNA was expressed at relatively high levels in malignant MCF-7, MDA-MB-231 and ZR-75-30 breast cancer cells (Figure 1c). The expression of FOXM1 in the tested breast cancer cell lines was further confirmed by western blot analysis, in which MCF-7 cells showed lower levels of FOXM1 protein than that of the other two cell lines (Figure 1d). Interestingly, growth curves of these three cell lines showed statistically difference on the rate of cell proliferation and MCF-7 cells proliferated slower than MDA-MB-231 or ZR-75-30 cells (Figure 1e). These results indicated that FOXM1 was commonly expressed in clinical tissue specimens and cell lines of human breast cancer and the levels of FOXM1 expression correlated with the ability of cell proliferation.
Knockdown of FOXM1 by AdFOXM1shRNA decreased the expression of cell cycle genes and inhibited the proliferation of breast cancer cells
FOXM1 is considered as an attractive target for the development of novel anticancer therapies.28, 29, 30 To develop innovative strategies for breast cancer gene therapy, we constructed an adenovirus-mediated shRNA expression system to knockdown FOXM1 expression and named this replication-defected adenovirus vector as AdFOXM1shRNA.30 AdLacZ control adenovirus infections determined that almost 100% of breast cancer cells were infected with the viral dosage at 10 p.f.u. per cell (Supplementary Figure S1). Western blot analysis further confirmed that the expression of FOXM1 protein was effectively suppressed in breast cancer cells at day 3 following infection with AdFOXM1shRNA (10 p.f.u. per cell) but not with AdLacZ (Figure 2a and Supplementary Figure S2). It is well known that FOXM1 regulates the transcription of cell cycle genes, such as cyclin B1 and CENPB, and knockdown of FOXM1 prevents the expression of these genes in multiple tumor cells.9, 10, 11, 12, 13, 14, 15 AdFOXM1shRNA infection decreased the expression of cyclin B1 and CENPB in MCF-7, MDA-MB-231 and ZR-75-30 breast cancer cells (Figure 2b), consistent with the published findings in other tumor cells.9, 10, 11, 12, 13, 14, 15 To determine the growth rate of FOXM1-depleted cells, breast cancer cells were infected with AdFOXM1shRNA or control AdLacZ and counted every day afterward. The growth curves showed that the cell growth of all the three breast cancer cell lines was inhibited dramatically by infection of AdFOXM1shRNA, compared with AdLacZ infection (Figure 2c). We observed no obvious difference in apoptosis among samples of the AdLacZ-infected, AdFOXM1shRNA-infected and non-treated cells (Supplementary Figure S3 and S4), indicating that the reduction in growth of the FOXM1-depleted cells was due to the inhibition of cell proliferation. This idea was further supported by the analysis of cell cycle progression with the MCF-7 and ZR-75-30 cell samples, in which the AdFOXM1shRNA-infected cells showed significant decrease in mitotic progression evidenced by a decrease in G1-phase cells and an increase in G2/M-phase cells compared with the untreated cells (Figure 2d). These data confirmed that AdFOXM1shRNA were effective in abolishing expression of FOXM1 and inhibiting the proliferation of breast cancer cells.
Tumorigenicity of breast cancer cells reduced by AdFOXM1shRNA
To investigate the effect of FOXM1 knockdown on tumorigenesis in vitro, we performed the soft agar assays to measure the ability of anchorage-independent growth of breast cancer cells infected with AdLacZ or AdFOXM1shRNA. ZR-75-30 cells were infected with Ad vectors (10 p.f.u. per cell) and plated in agar layers to grow for 10–14 days. AdFOXM1shRNA infection resulted in dramatic decrease in colony formation of ZR-75-30 cells (Figure 3a). Quantization of colony number demonstrated that depletion of FOXM1 expression by AdFOXM1shRNA inhibited the colony formation of the breast cancer cells (Figure 3b). To investigate the effect of FOXM1 knockdown on tumorigenesis in vivo, we inoculated the AdFOXM1shRNA-infected ZR-75-30 cells subcutaneously, and then compared the tumorigenicity of the FOXM1-silenced cells with that of the untreated or AdLacZ-infected cells. At 4 weeks post inoculation, tumor growth was nearly completely suppressed in mice inoculated with the FOXM1-silenced cells, whereas obvious tumors were formed in the control group mice inoculated with the untreated or AdLacZ-infected cells (Figure 4). As shown in Figures 4b and c, we observed only one small tumor formed in the four mice inoculated with the FOXM1-silenced cells. These observations suggested that AdFOXM1shRNA reduced the induction of the neoplastic phenotype of breast cancer cells in vivo.
Tumor growth of breast cancer cells was prevented by AdFOXM1shRNA in nude mouse xenografts
To determine the effect of AdFOXM1shRNA on tumor growth kinetics in vivo, we first generated ZR-75-30 cell xenografts in nude mice by injecting the cells (3 × 106 per mouse) subcutaneously to BalB/c nude mice in groups of six. The following AdFOXM1shRNA intratumoral injections (5 × 108 p.f.u. per mouse) were started at day 14 after the cell injections and repeated with a 3-day interval till the end of the procedure. We continued to measured the tumor volume in each animal at certain time points during the procedure and found that tumor growth was significantly inhibited in the group treated with AdFOXM1shRNA as compared with the control group (AdLacZ-treated; Figure 5b). In contrast with the large tumors produced by the AdLacZ-treated group, the mice treated with AdFOXM1shRNA produced small tumors (Figure 5a). Total RNA and protein lysates were isolated from the tumors of the three groups. The FOXM1 protein was almost undetectable in the AdFOXM1shRNA-treated samples (Figure 5c), suggesting that the inhibition of tumor growth in the AdFOXM1shRNA-treated group was a consequence of FOXM1 depletion in the tumors. The levels of FOXM1 protein in the tumors were also measured by immunostaining with the FOXM1 antibody and typical FOXM1-positive staining in nuclei was detected in the tumor tissue sections of the AdLacZ-treated group but not in that of the AdFOXM1shRNA-treated group (Figure 5d). In addition, the pools of combined six RNA samples from each group were tested with reverse transcription-PCR to measure the mRNA levels of FOXM1 and FOXM1’s target genes, such as cyclin B1, CENPB and PLK1. As predicted, the FOXM1 mRNA level was significantly reduced in the AdFOXM1shRNA-treated group and the downregulation of these FOXM1’s target genes was also observed (Figure 5e). We observed no obvious difference in apoptosis among samples of the AdLacZ-infected and AdFOXM1shRNA-infected tumors (Supplementary Figure S5), implicating that the reduction in growth of the FOXM1-depleted tumors was due to the inhibition of cell proliferation. The tumor tissue taken from each group was also examined through hematoxylin and eosin staining. The tissue sections of the AdLacZ-infected group showed a condensed morphology compared with that of the AdFOXM1shRNA-treated group (Figure 5f). These results indicated that AdFOXM1shRNA targeting FOXM1 elicited a strong antitumor effect on breast cancers in vivo.
FOXM1 expression is abnormally activated in many human malignancies. As a result of its involvement in regulating tumor cell proliferation, differentiation, DNA damage responses and migration, the attenuation of FOXM1 expression and activity has been found to increase therapeutic sensitivity of breast cancer therapeutic reagents. In human breast cancer samples, the overexpression of FOXM1 is related to poor prognosis and confers resistance to Herceptin and paclitaxel and targeting FOXM1 relieves therapeutic resistance in breast cancer.41 FOXM1 also confers acquired cisplatin resistance42 and epirubicin resistance43 in breast cancer cells. On the other hand, silencing FOXM1 expression leads breast cancer cells to become more sensitive to doxorubicin because of protective roles of FOXM1 in the cells facing doxorubicin-caused DNA damage.44 Furthermore, thiostrepton, a natural thiazole antibiotic with a potential druggability for breast cancer treatment, selectively induces cell cycle arrest and cell death in breast cancer cells through interacting directly with FOXM1 protein to inhibit FOXM1 functions.45, 46 In this study, we investigated the expression levels of FOXM1 in clinical samples and cell lines of breast cancer. We found that downregulation of FOXM1 elicited a dramatic effect on the inhibition of breast cancer cell proliferation. Our results provide additional evidence in support of the idea that FOXM1 is an attractive target for the development of novel anti-breast cancer therapies.
Cancer gene therapy, whose number of clinical trials takes up to 64.7% among all types of gene therapy clinical trials (the 2012 data of Journal of Gene Medicine Clinical Trial website (www.wiley.com//legacy/wileychi/genmed/clinical/)), is rapidly emerging as a possible therapeutic intervention for treatment of cancers. Among the strategies developed for cancer gene therapy such as blockage of cancer-related gene function, RNA interference (RNAi) technology attracts numerous attentions because of its robustness of gene silencing.47 RNAi describes the sequence-specific silencing of gene expression triggered by short double-stranded RNAs such as endogenous microRNAs or synthesized small interfering RNAs (siRNAs).48 Besides being utilized as a powerful technique in studying the biological function of genes, RNAi possesses a huge potential for its application in treatment of human diseases such as cancers.49, 50 The possibility of suppressing FOXM1 by FOXM1-specific siRNA in breast cancer cells has been tested in vivo. The expression levels of FOXM1 and its transcriptional targets such as cdc25B or aurora B kinase were reduced in subcutaneous MDA-MB-231 breast cancer tumors injected with a polyethylimine-based delivery agent encapsulating FOXM1 siRNA.51 Furthermore, FOXM1 downregulation in MDA-MB-231 and SUM149 cells by siRNA approach leads to inhibition of proliferation, migration and invasion of breast cancer cells through the modulation of extracellular matrix degrading factors.52
The successful application of RNAi in the disease treatment depends on effective and targeted delivery of specific siRNAs to cells and tissues. One approach is to use chemical or physical carriers for transfer of siRNAs.50, 51, 53 The other more popular approach is carried out by genetically modified viral vector delivery through the promoter-driven expression of shRNAs, which mimic endogenously processed microRNAs and are able to engage RNAi.54 Among the viral vectors of choice for RNAi expression, adenovirus is an efficient natural gene delivery system and is the most popular viral gene therapy vector in practice (www.wiley.com//legacy/wileychi/genmed/clinical/). In this study, we chose the adenovirus vector as our shRNA delivery vehicle. Adenoviruses are nonenveloped, double-stranded DNA viruses and >50 human Ad serotypes are identified to date. Ad serotype 5 is the most commonly used Ad serotype for gene delivery applications.55 Popularity of Ad vectors for therapeutic gene delivery is based on several advantages such as efficient transgene delivery and expression, transduction of both dividing and non-dividing cells, ease of propagation to high titers, episomal persistence of the Ad genome within the nucleus with minimal risk of genomic insertional mutagenesis, relative stability in blood following systemic administration, high capacity to accommodate foreign DNA and significant progress in our understanding of the biology of Ad.56, 57 The combination of the advantages of Ad as a gene delivery vector and RNAi technology potentiates the power of the approach for gene therapies, especially for cancer gene therapy. Ad-mediated RNAi technology has been evaluated for treatment of various types of human cancers, such as hepatocellular carcinoma, lung cancer, colon cancer, gastrointestinal stromal tumor58, 59, 60, 61, 62, 63 and offers a promising option for cancer gene therapy in the future.
In this study, we developed an efficient adenovirus-mediated shRNA expression system to specifically knockdown FOXM1 expression in breast cancer cells. We confirmed that this AdFOXM1shRNA vector was able to infect the cells with high infection efficiency and abolish the FOXM1 expression dramatically. As a consequence of the downregulation of FOXM1, the infection of AdFOXM1shRNA in the cancer cells significantly inhibited the proliferation and anchorage-independent growth of the cells. Furthermore, we conducted an in vivo experiment to confirm an effective suppression of the breast tumor growth through knockdown of FOXM1 gene expression by AdFOXM1shRNA intratumoral injection in an established breast cancer xenograft mice model. These results indicated that FOXM1 has an important role in breast cancer growth and the downregulation of FOXM1 expression possesses the therapeutic value for breast cancer treatment.
FOXM1 participates in the regulation of cell cycle in both the transition from G1 to S phase and the progression to mitosis.13, 14 It is well known that FOXM1 regulates the transcription of cell cycle genes, such as cyclin D1, Cdc25A, Skp2, cyclin B1, Cdc25B, PLK1, aurora B, survivin, CENPA, CENPB and knockdown of FOXM1 prevents the expression of these genes in multiple tumor cells.9, 10, 11, 12, 13, 14, 15 In this study, the downregulation of cyclin B1, CENPB and PLK1 observed in breast cancer cells by the FOXM1 knockdown is consistent with the published findings in other tumor cells. These data generally support the mechanisms to explain how silencing FOXM1 results in proliferation inhibition of breast cancer cells. In addition, FOXM1 has been shown to have roles in the regulation of angiogenesis in various types of solid tumors, such as gastric cancer,26 pancreatic cancer,25 clear cell renal cell carcinoma64 and glioblastoma,65 through stimulating the transcription of vascular endothelial growth factor,65 and the downregulation of FOXM1 is related to the inhibition of angiogenesis in these tumors. Given the evidence that the regulatory roles of FOXM1 are similar in various types of tumor cells, we imagine that the mechanism of FOXM1-mediated angiogenesis is involved in breast cancer development and may contribute to the inhibitory effects of AdFOXM1shRNA on breast tumor growth. This hypothesis will be elucidated by future studies.
On the whole, we found that the suppression of FOXM1 through an adenovirus RNAi system could suppress ex vivo cell proliferation and in vivo tumor growth of breast cancers. We concluded that the FOXM1 gene could be a therapy target for breast cancer and the potential antitumor effect of AdFOXM1shRNA may be tested for clinical development in the future.
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This work was supported by the Ministry of Science and Technology of China (grant number 2010DFB30300); and Natural Science Foundation of China (grant number 30871244, 81171949 to YT).
The authors declare no conflict of interest.
Supplementary Information accompanies the paper on Cancer Gene Therapy website
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Yang, C., Chen, H., Yu, L. et al. Inhibition of FOXM1 transcription factor suppresses cell proliferation and tumor growth of breast cancer. Cancer Gene Ther 20, 117–124 (2013). https://doi.org/10.1038/cgt.2012.94
- FOXM1 transcription factor
- breast cancer
- tumor gene therapy
- adenovirus vector
- RNA interference
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