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Objective: To inhibit the stemness maintenance potential of endometrial cancer and increase the sensitivity of endometrial cancer side population cells to chemotherapy drugs by inducing extensive deSUMOylation modification of proteins. Methods: Flow cytometry was used to sort and culture CD133(+) CD44(+) KLE endometrial cancer cell clone spheres. Protein expression level of small ubiquitin-related modifier 1 (SUMO1) and two stemness maintenance genes of tumor side population cells, octamer binding transcription factor-4 (Oct4) and sex determining region Y-box2 (Sox2), were detected by western blotting method. Lentivirus-mediated Sentrin/SUMO-specific proteases 1 (SENP1) gene was stably transfected into KLE side population cells. Western blotting was used to detect the protein expressions of SENP1, SUMO1, Oct4 and Sox2. The clone formation rate was compared between KLE side population cells with or without SENP1 overexpression. Flow cytometry was applied to detect cell cycle changes. 3-(4, 5-Dimethylthiazole-2)-2, 5-diphenyl-tetrazolium bromide (MTT) experiment and flow cytometry apoptosis method were used to detect the chemosensitivity of the side population of endometrial cancer cells to cisplatin. Tumor-bearing mouse models of endometrial cancer were established to detect the effect of SENP1 overexpression on the chemotherapy sensitivity of cisplatin. Results: Compared with CD133(-)CD44(-) KLE cells, CD133(+) CD44(+) KLE side population cells could form clonal spheres and express higher levels of SUMO1, Oct4 and Sox2 proteins (P<0.05). Compared with KLE side population cells that were not transfected with SENP1 gene, the expression level of SENP1 protein in KLE side population cells overexpressing SUMO1、Oct4 and Sox2 were lower. The clonal sphere formation rate was reduced from (25.67±5.44)% to (7.46±1.42)%, and cell cycle shifted from G(0)/G(1) phase to G(2) phase. IC(50) of cisplatin decreased from (55.46±6.14) μg/ml to (11.55±3.12) μg/ml, and cell apoptosis rate increased from (9.76±2.09)% to (16.79±3.44)%. Overexpression of SENP1 could reduce the tumorigenesis rate of KLE side population cells in vivo and increase their chemotherapy sensitivity to cisplatin (P<0.05). Conclusion: Overexpression of SENP1 can induce protein deSUMOylation modification, inhibit the stemness maintenance potential of endometrial cancer side population cells, and enhance their chemotherapy sensitivity, which provides a new reference for gene therapy of endometrial cancer.
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Animals , Female , Humans , Mice , Apoptosis , Cell Line, Tumor , Cisplatin/pharmacology , Cysteine Endopeptidases/metabolism , Endometrial Neoplasms/genetics , Side-Population Cells/pathology , SumoylationABSTRACT
Relapse and metastasis are frequent in colon cancer and may be linked to stem cell characteristics.This study isolated side population (SP) cells from a colon cancer cell line (Colo-320) and examined their self-renewal and differentiation abilities.Compared to non-SP (NSP) cells,SP colon cancer cells were more tumorigenic in vivo and exhibited more invasive characteristics and a greater ability to form colonies.Additionally,more cells were in G0/G1 phase and more highly expressed the multidrug resistance protein BCRP/ABCG2.We achieved enhanced chemotherapy sensitivity by transfecting SP cells with a hairpin-like,small interfering RNA (siRNA) eukaryotic expression plasmid targeting BCRP/ABCG2.
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[Abstract ] Objective Difficulties with the preparation of gastric cancer stem cells (CSCs) have been a main obstacle to the studies of gastric cancer .This article addresses the technology of the serum-free medium suspension cultivation of the MKN-45 gastric cancer cell line and screening of stem cells from the cell line based on the biomarkers of gastric CSCs . Methods MKN-45 cells were cultured in serum-free medium for 8 weeks and those in the logarithmic phase cultivated with hoechst 33342 followed by detection of the side cells by flow cytometry .When the side population cells reached 25%, all the cell microspheres were collected , hatched with CD133 and CD44, and subjected to fluorescence-activated cell sorting.The CDl33 +and CD44 +cells were selected as gastric CSCs . Results About 40%of the MKN-45 gastric CSCs were alive , prolif-erated, and formed floating cell balls .Side population cells constitu-ted 3.4% of the MKN-45 cells and 26.9% of the cell balls.The CDl33 +and CD44 +cells made up 11.2% of the MKN-45 cells and 90.3%of the cell balls. Conclusion Cell balls rich in CSCs can be successfully obtained by serum-free medium suspension culti-vation and CSCs can be screened out with hoechst 33342 and surface markers , which may serve as an experimental ground for the stud-ies of gastric CSCs .
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Objective To isolate side population (SP) cells from an established ovarian cancer (OC)cell line,characterize these cells,and examine their drug resistance. Methods SP and non-SP (NSP) cells were isolated by fluorescence-activated cell sorting (FACS),and cultured in differential conditions,then detected their SP ratio to compare their capability of differentiation and self-renewal. Moreover,SP and NSP cell tumorigenesis was examined by subcutaneous and intraperitoneal injection of these cells to nonobes ediabetic(NOD)-severe combined immundeficient(SCID)mice. Drug resistance to cisplatin was examined by cell counting kit-8 (CCK-8).Results SP cells could be isolated stablly and insistently. There was(4.81 ± 0.43)%of SP cells in the established OC cell line and(4.89 ± 0.33)%of SP cells after cultured the isolated SP cells in differentiation condition,and there was no significant different between these two quantities (P>0.05). However,after cultured the NSP cells,there was only (0.10 ± 0.03)%of SP cells which was significantly lower than that contained in the OC cell line(P<0.01). In the tumorigenesis assay 1.0 × 103 SP cells were injected subcutaneously and formed the xenografted tumors in 6 weeks(3/3),and 1.0×104 NSP cells were injected subcutaneously and did not form xenografted tumors in 12 weeks(0). The tumorigenic capability of SP cells was higher than that of NSP cells(P<0.01). Both the original and the xenografted tumors were low differentiated serous cystadenocarcinomas and expressed the ovarian serous cystadenocarcinomas CA125 marker after stained by HE and immunohistochemistry. Simultaneously,the SP cells were also capable to form tumors as shown by intraperitoneal injection. In the drug resistance assay shown that the 50% inhibitory concentration (IC50) of the SP and NSP cells were respectively(2.33 ± 0.14)μg/ml and(1.60 ± 0.04)μg/ml(P<0.05). After treated the unsorted OC cells with cisplatin,the quantity of SP cells increased to(40.10 ± 4.22)%and there was significant difference,when compared to the untreated cells which was(4.81±0.43)%(P<0.01). The SP cells survival rate was(58.7± 3.3)%when treated with cisplatin at its IC50 dose,and the rate decreased to(7.2±1.3)%(P<0.01)when verapamil was present. Conclusions The SP cells could be isolated from the established OC cell line. They had the capacities of self-renewal,differentiation,and tumorigenesis,and the new tumor demonstrated the original tumor′s phenotype. The SP cells also had stem cells′ biological characteristics and is resistant to cisplatin.
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Objective To detect and separate the side population cells(SP) from multiple myeloma (MM) cell lines PRIM8226,and to study their biological characteristics.Methods Fluorescence activated cell sorter (FACS) and Hoechst33342/PI dye were used to sort SP cells of PRIM8226.The multiplication capacity was tested by the growth curve and MTT test,SP cells proportion and the cell cycle were analyzed by flow cytometry,the colony-formtion ability was compared in terms of colony forming experiment,the expression of c-myc,KIF4,SOX2,OCT4 was tested by RT-PCR.The oncogenicity of the cells was analyzed by nude mouse transplantation tumor experiment in vivo.Results The ratio of SP cells in PRIM8226 was (1.78±0.89) ％.More SP cells in the G0 / G1 period,(44.34±3.09) ％ vs (28.49±1.97) ％,P ＜ 0.05,and fewer cells in S phase than MP cells,(38.83±3.69) ％ vs (51.49±4.62) ％,P ＜ 0.05.There were no difference in the expression of CD38 and CD138 between SP cells and MP cells,respectively,(78.5±8.5) ％ vs (82.0±4.0) ％ and (72.3±15.7) ％ vs (84.3±11.9) ％,P ＞ 0.05.Colony formation assay showed that the colony forming efficiency of the SP cells was higher than the MP cells,single cell clone diameter,the number of clone forming,the clone formtion rate were significantly higher than MP cells,0.280±0.016 vs 0.118±0.019,1 722±127 vs 358±14,(86.1±3.46) ％ vs (17.9±1.88) ％,P ＜ 0.05.The mRNA expression levels of c-myc,KIF4,SOX2,OCT4 in SP cells were higher than those in MP cells,c-myc (29.90±3.73) ％ vs (16.84±2.35) ％,KIF4 (29.97±2.89) ％ vs (19.06±1.23) ％,SOX2 (40.00±4.58) ％ vs (16.62±2.09) ％,OCT4 (32.96±0.92) ％ vs (23.27±0.92) ％,all P ＜ 0.05.Nude mouse transplantation tumor experiment in vivo showed the oncogenicity of the SP cells was more stronger than MP cells (5×103 vs 5×l05).Conclusion There are notably difference in the cell cycle,colony formation assay,the mRNA expression levels and oncogenicity,but no difference in the expression of CD38 and CD138,the proliferation ability between SP cells and MP cells.
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Objective To analysis the malignant performance characteristics of tumor stem cell-like side popula-tion cells in patients with cervical cancer. Methods The cervical cancer cells were obtained from surgical resection tumor tissue. The tumor stem cell-like side population cells were isolated by flow cytometry. The cell growth curve was drawn by MTT assay. The invasion ability of tumor cells was compared by transwell assay. The clonogenic capacity was detected by clone formation in soft agar. The expression level of ABCG2 protein, a drug-resistant gene, was detected by immunofluores-cence method. Finally, these cells were transplated into the subcutaneous of de thymus mice. The rate of tumor formation was compared between groups. Results The results from flow cytometry assay showed the percentage of cervical cancer stem cell-like side population cells was 1.39%. Compared with the non-side population cells, the side population cells grow quickly, showed the enhanced invasion ability and colony forming ability. There was more high expression level in ABCG 2 protein of side population cells. The tumor form rate was 100%(10/10) in the side population cells and the non-side popula-tion cells was 20%(2/10). Conclusion The cervical cancer stem cell-like side population cells have more malignant perfor-mance characteristics than that of non-side population cells, which maybe a core target for cancer gene therapy in the future.
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Side population cells (SPs) are selected by the efflux features of fluorescent dye Hoechst33342.SPs have the characteristics of cancer stem cells,and play an extremely important role in the occurrence and development of tumors.At present,the SPs in common types of malignant tumor have been studied extensively at home and abroad.The study of SPs may shed some light on the diagnosis and treatment of cancer.
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AIM:To investigate the role of side population ( SP) cells in multidrug resistance of colon cancer cells and microRNA biomarkers of SP cells in colon cancer cells .METHODS:SP cells in colon cancer cells were sorted by flow cytometry .The cell viability was measured by MTT method .MicroRNA expression profiles were detected by mi-croRNA chip.MicroRNA expression was verified by real-time PCR.RESULTS:The ratios of SP cells in HCT-15, HT-29 and LoVo colon cancer cell lines were 16.75%, 13.02%and 9.52%, respectively.In all 3 colon cancer cell lines, IC50 of the antitumor drugs including 5-fluorouracil , oxaliplatin and adriamycin for the SP cells were significantly higher than those for non-SP cells (P<0.05).MicroRNA profiling showed that miR-5000-3p, miR-5009-3p and miR-552 were all up-regulated in the SP cells of all 3 colon cancer cell lines .This result was verified by real-time PCR.CONCLUSION:miR-5000-3p, miR-5009-3p and miR-552 are all up-regulated in the SP cells of colon cancer cell lines , and may be the poten-tial microRNA biomarkers of SP cells in colon cancer .
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OBJECTIVE: To design and prepare a novel polymeric micelles preparation for hydrophobic salinomycin (SAL), then evaluate the effects of SAL micelles on cancer stem cells in vitro. METHODS: SAL was entrapped into polymeric micelles constructed from amphiphilic diblock copolymer of poly (ethylene glycol)-block-poly (ε-caprolactone) (mPEG-b-PCL). Firstly, the process of preparing micelles and formulation composition were optimized. Then, the physicochemical properties such as particle size distribution, shape and surface morphology, stability and release rates of SAL-loaded micelles were studied. Finally, the side population (SP) cells were analyzed to evaluate the effects of SAL micelles on the MCF-7 cells. RESULTS: The optimal formulation of drug-loaded micelles was mPEG-b-PCL copolymers and SAL (20:1, w/w); the average particle size of SAL-loaded micelles was less than 30 nm, with narrow size distribution, uniform spherical shape and good stability. In vitro studies demonstrated that SAL-loaded micelles were able to decrease the proportion of SP cells. CONCLUSION: Polymeric micelles are capable of overcoming the poor solubility of SAL, and SAL-loaded micelles can selectively deplete breast cancer stem cells.
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Based on the theory of cancer stem cells (CSCs),people have been searching for the treatments of malignant cancers.Gastric cancer side population cells (SP) have the characteristics of CSCs.Searching for the molecular targeted therapy strategy of gastric cancer which embarks from the gastric cancer SP and is based on the theory of CSCs provides a new direction for the treatment,early diagnosis,therapeutic effect and prognosis of gastric cancer.
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Objective To assay and determine whether the human acute monocytic leukemia cell line THP-1 contains side populations (SP) cells,and to increase the proportion of SP cells using cytarabine (Ara-C).Methods Fluorescent microscope and flow cytometry (FCM) were employed for detecting the percentage of SP cells in THP-1 cells.Then,SP and non-SP (NSP) subpopulations were collected and identified.Finally,THP-1 cells were incubated with different concentrations of Ara-C for 24 hours and detected the proportion of SP cells,respectively.Results The results demonstrated that the percentage of SP cells was (1.81 ± 0.99) ％ in THP-1 cells.A majority of the SP cells remained in the G0/G1 phase,and the expressions of CD34 + and CD34 + CD38-and the proliferative ability of the SP cells were higher than those of NSP cells (P ＜ 0.05).The mRNA expression of multidrug resistance genes (ABCG2,ABCB1),apoptosis regulation genes (Bcl-2) and the Bcl-2/Bax ratio of SP cells were higher than those of NSP cells.SP cells have been shown to be more tumorigenic than NSP cells.After co-culture with Ara-C,the proportion of SP cells increased significantly and presented in a concentration-dependent manor.Conclusions All of these findings suggest that the THP-1 cell line contains SP cells and the SP cells possess some intrinsic stem cell properties.The proportion of SP cells can be increased when co-cultured with Ara C,and this technique is a useful and important application for the study of LSCs.
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PURPOSE: Lactobacillus casei (L. casei) is known to exert anti-proliferation effects on many types of cancer cells. However, the effect of L. casei on liver cancer has not been reported. Accordingly, the aim of this study was to determine the anti-cancer effect of L. casei extract on Huh7 cells. MATERIALS AND METHODS: L. casei ATCC393 extract was prepared and purified. After the treatment of L. casei extract on Huh7 cells, cell viability, cell cycle arrest and cell death were analyzed by flow cytometry. The expression levels of tumor necrosis factor-alpha receptor 1 (TNFR1) and death receptor 3 (DR3) mRNA related with extrinsic apoptosis were assessed by reverse transcription polymerase chain reaction. Additionally, P21 and P27 cell cycle proteins as well as Caspase-3, -8, -9, phospho-Bad and Bcl-2 apoptosis proteins were analyzed by western blot analysis. To determine the effect of L. casei extract on cancer stem-like cells, we analyzed changes in side population fraction through flow cytometry. RESULTS: The cell viability of Huh7 cells treated with L. casei extract was decreased by 77%, potentially owing to increases in the rates of Huh7 cells arrested in the G2/M phase (3% increase) and that underwent apoptosis (6% increase). The expression levels of TNFR1 and DR3 mRNA, as well as P21 and P27 cell cycle proteins, were increased. Meanwhile, the expressions of caspase-8, -9, phospho-Bad and Bcl-2 proteins decreased. However, in the case of side population cells, no remarkable changes were observed. CONCLUSION: L. casei extract exerts a potent anti-tumor effect on the viability of liver cancer cells, although not on cancer stem-like cells.
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Humans , Apoptosis/drug effects , Carcinoma, Hepatocellular/pathology , Caspase 8/metabolism , Caspase 9/metabolism , Cell Cycle Checkpoints/drug effects , Cell Extracts/pharmacology , Cell Line, Tumor , Cell Proliferation/drug effects , Cyclin-Dependent Kinase Inhibitor p21/metabolism , Cyclin-Dependent Kinase Inhibitor p27/metabolism , Cytostatic Agents/pharmacology , Flow Cytometry , Gene Expression Regulation, Neoplastic/drug effects , Lacticaseibacillus casei/chemistry , Liver Neoplasms/pathology , Proto-Oncogene Proteins c-bcl-2/metabolism , RNA, Messenger/metabolism , Receptors, Tumor Necrosis Factor, Member 25/metabolism , Receptors, Tumor Necrosis Factor, Type I/metabolism , bcl-Associated Death Protein/metabolismABSTRACT
Cancer stem cell (CSC) research has increased exponentially to gain further insight into the mechanisms underlying both carcinogenesis and chemotherapy resistance. The present study was performed to explore the potential value of a side population (SP) assay for identifying and characterizing putative CSCs among canine lymphoma cells. Canine lymphoma cells from cell lines and clinical samples were subjected to the SP assay consisting of Hoechst 33342 staining and subsequent flow cytometric analysis. The SP assay revealed various amounts of a SP fraction among the canine lymphoma cells. The percentages of SP were not affected by inhibitors of membrane transporters, verapamil hydrochloride, or fumitremorgin C. Most of the canine lymphoma cells expressed high levels of Bmi-1 and membrane transporter proteins such as ABCG2 and phosphorylated (p)-glycoprotein. This investigation lays the groundwork for further studies of the biological behaviors and molecular characteristics of CSCs in cases of canine lymphoma.
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Animals , Dogs , Benzimidazoles/metabolism , Cell Line, Tumor , Dog Diseases/diagnosis , Flow Cytometry/methods , Fluorescent Dyes/metabolism , Gene Expression Regulation, Developmental , Lymphoma/diagnosis , Neoplastic Stem Cells/drug effects , Side-Population Cells/drug effectsABSTRACT
ObjectiveTo identify the presence of side population (SP) cells in human ovarian cancer cell line OVCAR-3 and to investigate whether SP cells have the characteristics of cancer stem cells.MethodsSP and non-SP (NSP) cells from OVCAR-3 were isolated by fluorescence-activated cell sorting after being stained by DNA-binding dye Hoechst 33342.Limiting dilution transplantation assay,realtime PCR,and drug sensitivity assay were performed to compare the tumorigenic ability,differentiation ability in vivo,the mRNA expressiou of stemness marker (Oct-4,Klf4,and Nanog) and ATP-binding cassette (ABC) transporter (ABCG2,ABCB1,and ABCC2),and response to multiple drugs (cisplatin,paclitaxel,doxorubicin,and mitoxantrone )between SP and NSP cells.ResultsA few of SP cells [ ( 1.13 ±0.39) ％ ] which were sensitive to reserpine were identified in OVCAR-3 cells.The injection of as few as 102 SP cells initiated tumors in two of five mice.Tumor latency was 52 -61 days.However,the NSP cells did not generate any tumors in mice until 104 NSP cells were injected (two of five mice).Tumor latency was 64 - 98 days.Tumorigenicity of SP cells was enhanced by at least 100-fold than that of NSP cells.The SP cells regenerated both SP [ ( 2.09 ± 0.73 ) ％ ] and NSP populations in vivo with a fraction size that was comparable to the original population.The mRNA expression ofstemness genes Oct-4,Klf4 and ABC transporters ABCG2,ABCC2 genes were elevated in SP cells compared to NSP cells,the fold changes were 1.95±0.41 (P＜0.05),4.26 ±0.63 (P＜0.01),3.22±0.36 (P＜0.01),and 1.76±0.26 (P＜0.01 ),respectively.The relative activity of SP and NSP cells were 0.757 ± 0.105 versus 0.474 ± 0.035 (P＜0.01),0.521 ±0.092 versus 0.384 ±0.073 (P＜0.05),0.742 ±0.051 versus 0.526 ±0.088 (P ＜0.01 ),and 0.690 ± 0.096 versus 0.466 ± 0.112 ( P ＜ 0.01 ) when they exposed to 0.25 μg/ml cisplatin, 0.01μmol/Lpaclitaxel, 0.25μmol/Ldoxorubicin, and0.05μg/mlmitoxantrone,respectively.ConclusionsSP cells from OVCAR-3 have enhanced self-renewal,differentiation,and tumorinitiating capacity compared to NSP cells.The mRNA expression of stemness genes and ABC transporters are markedly elevated in SP cells,which showed resistance to multiple chemotherapeutic drugs and have characteristics of cancer stem-like cells.Therefore,SP phenotype could be used as a marker to isolate the cancer stem-like cells in ovarian cancer.
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Objective To separate the side population cells(SP) from breast cancer MCF-7 cell line,and observe its biological characteristics.Methods Flow cytometry and Hcechst 33342 dye efflux assay were used to isolate SP cells and non-SP cells from the MCF-7 cell line of human breast cancer.Tumorigenicity of the two subpopulations was observed by a soft agar cloning method.Results The results of FACS analysis indicated that (6.5 ± 0.4 ) ％of the MCF-7 cells were SP cells;The vitro colony formation rate of SP cells was(38.5 ±9.4)％,and higher than that of non-SP cells ( 8.4 ± 2.6 ) ％ ( t =5.34,P ＜ 0,05 ).Concluslon The SP cells sorted from MCF-7 cell line enriched tunor stem cells,which exhibited high tumorigenicity.It indicated that SP cells should play a principal role in breast cancer.
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ObjectiveTo investigate the expression of stem cell marker adenosine triphosphate (ATP)-binding cassette transporter 2 (ABCG2) in the tissue and side population (SP) of a cell line A431 of human cutaneous squamous cell carcinoma(SCC).MethodsSP cells were separated by flow cytometry from cultured A431 cells.Methyl thiazolyl tetrazolium(MTT) assay was used to evaluate the proliferative ability of,reverse transcription-PCR to determine the expression of ABCG2 in,SP and non-SP cells.Immunohistochemistry (MaxVision method) was carried out to detect the expression of ABCG2 protein in tissue specimens from 10 patients with SCC.ResultsSP cells existed in cultured A431 cells,and accounted for about 1.1％ of A431 cells.The SP cells had a stronger growth and colony-forming ability than non-SP cells did.The number of cell clones formed by SP cells and non-SP cells was 114.8 ± 4.95 and 44.5 ± 3.67,respectively,per well in a 24-well plate( t =27.92,P ＜ 0.01 ).The expression level of ABCG2 mRNA was significantly higher in SP cells than in non-SP cells(t =5.22,P＜ 0.01).There existed a small number of ABCG2 positive cells in SCC tissue,and ABCG2 was mainly expressed in the cytoplasm and membrane of tumor cells.ConclusionsSP cells exist in A431 cells,which have characteristics of stem cells and highly express ABCG2.ABCG2 may be a potential stem cell surface marker of SCC.
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In the occurrence and development of tumors, side population cells play an extremely important role. They have the characteristics of cancer stem cells, especially their potential of tumor originating, and stronger drug-resistance. The study of biological characteristics, sorting and training methods of side population cells and the relationship between side population cells and tumor drug-resistance may shed some light on the diagnosis and treatment of cancer.
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Objective To investigate the drug resistance of side population cells in human gallbladder cancer cell line GBC-SD and explore its mechanism. Methods Drug sensitivity assays of 5chemotherapeutic agents were performed on side population cells (SP) and non-SP cells of GBC-SD.GBC-SD was cultured and then treated with the chemotherapeutic agent gemcitabine. The frequency of SP by FACS was measured. RT-PCR and Western blotting were used to detect the expression of AB-CG2 in both the SP and the corresponding non-SP subsets. Results After 1 d treatment with 4 chemotherapeutic agents (gemcitabine, cisplatin, 5-fluorouracil and mitoxantrone) in IC50 concentration to GBC-SD cell line, the reproductive ability of SP was higher than that of non-SP (P0.05). The percentage of SP in GBC-SD treated with chemotherapeutic agent gemcitabine after 3 weeks was sharply elevated by FACS (8.02% ±0.13% vs 0.62% ±0.08%, P<0.05), and the expression of ABCG2mRNA and protein were increased in SP as compared with non-SP. Conclusion SP from human gallbladder cancer cell line GBC-SD, like stem cell, showed a heighten resistance to drugs. Increased expression of ABCG2 was largely responsible for the multi-drug resistance.
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Mounting evidence has shown that side population (SP) cells are enriched for cancer stem cells (CSCs) responsible for cancer malignancy.In this study,SP technology was used to isolate a small subpopulation of SP cells in human gallbladder cancer cell line GBC-SD,and SP cells which had superior potential for proliferation in vitro and tumorigenesis in vivo were identified.Importantly,the abundance of GBC-SD SP cells was increased by a transforming growth factor-β (TGF-β)-induced epithelial-mesenchymal transition (EMT),and this effect was accompanied with a strong up-regulation of ABCG2 mRNA expression,and a decreased sensitivity to mitoxantrone.SP cells were restored upon the removal of TGF-β and the reversion of the cells to an epithelial phenotype,and smad3-specific siRNA reduced SP abundance in response to TGF-β.In conclusion,TGF-β-induced EMT by smad-dependent signaling pathway promotes cancer development and anti-cancer drug resistant phenotype by augmenting the abundance of GBC-SD SP cells,and a better understanding of mechanisms involved in TGF-β-induced EMT may provide a novel strategy for preventing cancer progression.
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Cancer stem cells (CSCs) are a small proportion of tumor cells with the property of stem cells in the tumor tissue; they are capable of self-renewal, multi-lineage differentiation and serve as the source of tumor cells and tumor tissues. The discovery of multiple myeloma CSCs and the study on its relationship with side population cells and niche provide a new interpretation on the pathogenesis of multiple myeloma.