Ovarian Cancer Stem Cells: Characterization and Role in Tumorigenesis.

Ovarian cancer is a heterogenous disease with variable clinicopathological and molecular mechanisms being responsible for tumorigenesis. Despite substantial technological improvement, lack of early diagnosis contributes to its highest mortality. Ovarian cancer is considered to be the most lethal female gynaecological cancer across the world. Conventional treatment modules with platinum- and Taxane-based chemotherapy can cause an initial satisfactory improvement in ovarian cancer patients. However, approximately 75-80% patients of advanced stage ovarian cancer, experience relapse and nearly 40% have overall poor survival rate. It has been observed that a subpopulation of cells referred as cancer stem cells (CSCs), having self renewal property, escape the conventional chemotherapy because of their quiescent nature. Later, these CSCs following its interaction with microenvironment and release of various inflammatory cytokines, chemokines and matrix metalloproteinases, induce invasion and propagation to distant organs of the body mainly peritoneal cavity. These CSCs can be enriched by their specific surface markers such as CD44, CD117, CD133 and intracellular enzyme such as aldehyde dehydrogenase. This tumorigenicity is further aggravated by the epithelial to mesenchymal transition of CSCs and neovascularisation via epigenetic reprogramming and over-expression of various signalling cascades such as Wnt/ß-catenin, NOTCH, Hedgehog, etc. to name a few. Hence, a comprehensive understanding of various cellular events involving interaction between cancer cells and cancer stem cells as well as its surrounding micro environmental components would be of unmet need to achieve the ultimate goal of better management of ovarian cancer patients. This chapter deals with the impact of ovarian cancer stem cells in tumorigenesis which would help in the implementation of basic research into the clinical field in the form of translational research in order to reduce the morbidity and mortality in ovarian cancer patients through amelioration of diagnosis and impoverishment of therapeutic resistance.

Gene-expression profile and postpartum transition of bovine endometrial side population cells†.

The mechanism of bovine endometrial regeneration after parturition remains unclear. Here, we hypothesized that bovine endometrial stem/progenitor cells participate in the postpartum regeneration of the endometrium. Flow cytometry analysis identified the presence of side population (SP) cells among endometrial stromal cells. Endometrial SP cells were shown to differentiate into osteoblasts and adipocytes. RNA-seq data showed that the gene expression pattern was different between bovine endometrial SP cells and main population cells. Gene Set Enrichment Analysis identified the enrichment of stemness genes in SP cells. Significantly (false discovery rate < 0.01) upregulated genes in SP cells contained several stem cell marker genes. Gene ontology (GO) analysis of the upregulated genes in SP cells showed enrichment of terms related to RNA metabolic process and transcription. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis of upregulated genes in SP cells revealed enrichment of signaling pathways associated with maintenance and differentiation of stem/progenitor cells. The terms involved in TCA cycles were enriched in GO and KEGG pathway analysis of downregulated genes in SP cells. These results support the assumption that bovine endometrial SP cells exhibit characteristics of somatic stem/progenitor cells. The ratio of SP cells to endometrial cells was lowest on days 9-11 after parturition, which gradually increased thereafter. SP cells were shown to differentiate into epithelial cells. Collectively, these results suggest that bovine endometrial SP cells were temporarily reduced immediately after calving possibly due to their differentiation to provide new endometrial cells.

Sinomenine inhibits hypoxia induced breast cancer side population cells metastasis by PI3K/Akt/mTOR pathway.

Sinomenine is an alkaloid derived from Chinese medicinal plant Sinomenium acutum. Our previous studies suggested that sinomenine can inhibit the metastasis of breast cancer. However, whether sinomenine can inhibit the metastasis characteristics of breast cancer side population (SP) cells is still unknown. In present study, we isolated the side population (SP) cells from MDA-MB-231 cells by fluorescence-activated cell sorting (FACS). MDA-MB-231 SP cells were treated with different concentrations of sinomenine at the absence or presence of hypoxia, and cell viability were measured by CCK-8 assay. The transwell invasive assay were conducted to assess of the effect of sinomenine on the invasion of hypoxic MDA-MB-231 SP cells. The protein expression was detected by Western blot assay. Sinomenine inhibited the cell viability and invasion of hypoxic MDA-MB-231 SP cells. Western blot assay results showed that the upregulation of MMP-2 and MMP-9 by hypoxia was inversed by sinomenine. Additionally, it was found that sinomenine suppressed the activation of PI3K/Akt/mTOR pathway under hypoxia in MDA-MB-231 SP cells. Moreover, the inhibiton of sinomenine on metastasis of hypoxic MDA-MB-231SP cells and PI3K/Akt/mTOR pathway could be rescued by PI3K activator IGF-1. Our study suggested that sinomenine inhibits invasion of breast cancer SP cells under hypoxia through PI3K/Akt/mTOR pathway.

Overexpression of DUSP6 enhances chemotherapy-resistance of ovarian epithelial cancer by regulating the ERK signaling pathway.

Objective: DUSP6 is a negative regulator of the ERK signaling pathway and plays an important role in chemotherapy-resistance. Previously we showed that DUSP6 is overexpressed in ovarian cancer side population (SP) cells that possess cancer stem cell-like properties and are quiescent and chemotherapy-resistant. Here, we explore the effects of DUSP6 on chemotherapy-resistance by examining its regulation of the ERK signaling pathway and G0/G1 cell cycle arrest. Methods: mRNA and protein expression of DUSP6 and G0/G1 cell cycle checkpoint regulating proteins (CyclinD1, CyclinD3 and CyclinE2) was evaluated among ovarian cancer cell lines and tissue samples. Ovarian cancer cells were transiently transfected to overexpress DUSP6. After treatment with cisplatin, cell viability was measured by the MTS assay at 48 hours and the half maximal inhibitory concentration (IC50) for each cell line was calculated. Subcellular localization and cell cycle analysis were determined by using immunofluorescence and FACS, respectively. Results: SKOV3 and OVCAR8 SP cells were shown to express higher levels of DUSP6 and lower levels of CyclinD3 compared with non-SP (NSP) cells (P<0.001). Among 39 ovarian cancer tissue samples, expression of DUSP6 in the chemotherapy-resistant group (12 samples) was higher than in the chemotherapy-sensitive group (27 samples) (P<0.05). While a lower level of expression of CyclinD3 was seen in the chemotherapy-resistant group, it was not statistically different from the chemotherapy-sensitive group. HO8910 cells where shown to have higher IC50 to cisplatin than SKOV3 or OVCAR8 cells, and this correlated with higher levels of DUSP6 expression. Overexpression of DUSP6 in SKOV3 cells led to an increase in cisplatin IC50 values (P<0.05), and also markedly reduced the expression levels of phospho-ERK1/2 and CyclinD3 and to the predominance of cells in the G0/G1 phase. Conclusion: Our findings reveal an enhancement of chemotherapy-resistance and a predominance of cells in G1 cell cycle arrest in DUSP6-overexpressing ovarian cancer cells. This suggests that overexpression of DUSP6 promotes chemotherapy-resistance through the negative regulation of the ERK signaling pathway, increasing the G0/G1 phase ratio among ovarian cancer cells, and leading to cellular quiescence.

Gastrin regulates ABCG2 to promote the migration, invasion and side populations in pancreatic cancer cells via activation of NF-κB signaling.

Gastrin is absent in most normal adult pancreatic tissues but is highly expressed in pancreatic cancer tissues. Although Gastrin expression was reported to be associated with tumor proliferation in human pancreatic cancer, studies on the relationship between Gastrin and tumor metastasis in pancreatic cancer are rare. In this study, we performed an analysis to determine the effects of Gastrin on modulating the side populations, cell proportion and tumor cell metastatic potential and invasion activity and explored its mechanisms in pancreatic cancer. We indicated that Gastrin and ABCG2 were widely expressed in pancreatic cancer cell lines and overexpressed in cancer tissues. Gastrin induced ABCG2 expression, and this effect was mediated by NF-κB activation. Gastrin regulated the SP proportion of BxPC-3 cells via modulating ABCG2 expression. Through the regulation of the functions of NF-κB/ABCG2, Gastrin functionally promoted the migration and invasion in pancreatic cancer cell. The present study indicated that Gastrin induced ABCG2 expression by activating NF-κB and thereby modulated the SP proportion, tumor cell metastatic potential and invasion activity in pancreatic cancer. Gastrin could serve as an effective therapeutic target for the metastasis of pancreatic cancer.

Up-regulation of lymphocyte antigen 6 complex expression in side-population cells derived from a human trophoblast cell line HTR-8/SVneo.

The continual proliferation and differentiation of trophoblasts are critical for the maintenance of pregnancy. It is well known that the tissue stem cells are associated with the development of tissues and pathologies. It has been demonstrated that side-population (SP) cells identified by fluorescence-activated cell sorting (FACS) are enriched with stem cells. The SP cells in HTR-8/SVneo cells derived from human primary trophoblast cells were isolated by FACS. HTR-8/SVneo-SP cell cultures generated both SP and non-SP (NSP) subpopulations. In contrast, NSP cell cultures produced NSP cells and failed to produce SP cells. These SP cells showed self-renewal capability by serial colony-forming assay. Microarray expression analysis using a set of HTR-8/SVneo-SP and -NSP cells revealed that SP cells overexpressed several stemness genes including caudal type homeobox2 (CDX2) and bone morphogenic proteins (BMPs), and lymphocyte antigen 6 complex locus D (LY6D) gene was the most highly up-regulated in HTR-8/SVneo-SP cells. LY6D gene reduced its expression in the course of a 7-day cultivation in differentiation medium. SP cells tended to reduce its fraction by treatment of LY6D siRNA indicating that LY6D had potential to maintain cell proliferation of HTR-8/SVneo-SP cells. On ontology analysis, epithelial-mesenchymal transition (EMT) pathway was involved in the up-regulated genes on microarray analysis. HTR-SVneo-SP cells showed enhanced migration. This is the first report that LY6D was important for the maintenance of HTR-8/SVneo-SP cells. EMT was associated with the phenotype of these SP cells.

Serum-free culture of the MKN-45 gastric cancer cell line and preparation of stem cells / 医学研究生学报

[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 .

miRNA-148b suppresses hepatic cancer stem cell by targeting neuropilin-1.

The existence of cancer stem cells (CSCs) is considered as a direct reason for the failure of clinic treatment in hepatocellular carcinoma (HCC). Growing evidences have demonstrated that miRNAs play an important role in regulation of stem cell proliferation, differentiation and self-renewal and their aberrances cause the formation of CSCs and eventually result in carcinogenesis. We recently identified miRNA-148b as one of the miRNAs specifically down-regulated in side population (SP) cells of PLC/PRF/5 cell line. However, it remains elusive how miRNA-148b regulates CSC properties in HCC. In the present study, we observed that overexpression or knockdown of miR-148b through lentiviral transfection could affect the proportion of SP cells as well as CSC-related gene expression in HCC cell lines. In addition, miR-148b blocking could stimulate cell proliferation, enhance chemosensitivity, as well as increase cell metastasis and angiogenesis in vitro. More importantly, miR-148b could significantly suppress tumorigenicity in vivo. Further studies revealed that Neuropilin-1 (NRP1), a transmembrane co-receptor involved in tumour initiation, metastasis and angiogenesis, might be the direct target of miRNA-148b. Taking together, our findings define that miR-148b might play a critical role in maintenance of SP cells with CSC properties by targeting NRP1 in HCC. It is the potential to develop a new strategy specifically targeting hepatic CSCs (HCSCs) through restoration of miR-148b expression in future therapy.

A role for matrix stiffness in the regulation of cardiac side population cell function.

The mechanical properties of the local microenvironment may have important influence on the fate and function of adult tissue progenitor cells, altering the regenerative process. This is particularly critical following a myocardial infarction, in which the normal, compliant myocardial tissue is replaced with fibrotic, stiff scar tissue. In this study, we examined the effects of matrix stiffness on adult cardiac side population (CSP) progenitor cell behavior. Ovine and murine CSP cells were isolated and cultured on polydimethylsiloxane substrates, replicating the elastic moduli of normal and fibrotic myocardium. Proliferation capacity and cell cycling were increased in CSP cells cultured on the stiff substrate with an associated reduction in cardiomyogeneic differentiation and accelerated cell ageing. In addition, culture on stiff substrate stimulated upregulation of extracellular matrix and adhesion proteins gene expression in CSP cells. Collectively, we demonstrate that microenvironment properties, including matrix stiffness, play a critical role in regulating progenitor cell functions of endogenous resident CSP cells. Understanding the effects of the tissue microenvironment on resident cardiac progenitor cells is a critical step toward achieving functional cardiac regeneration.

Androgen receptor increases CD133 expression and progenitor-like population that associate with cisplatin resistance in endometrial cancer cell line.

Endometrial cancer (EMC) is a sex steroid hormone-related female malignancy. Androgen and androgen receptor (androgen/AR) signals have been implicated in EMC progression. Cancer stem/progenitor cells (CSPCs) are suspected to link to chemoresistance in patients with EMC. In this study, we examined the androgen/AR roles in cisplatin resistance and CSPC population. We found AR expression increased naive EMC side population, CSPC population, cell migration, and epithelial-mesenchymal transition. Meanwhile, it decreased cisplatin cytotoxic effect on EMC cells. Collaterally, endogenous AR expressions in EMC cells were upregulated in the cisplatin-resisting state. Moreover, AR expression could further enhance CD133 expression, CSPC-related markers, and drug-resistance gene messenger RNA expression in EMC cells. Finally, the AR-associated gene expression might go through indirect regulation. This is the first report revealing AR function on EMC cells' CSPC and cisplatin resistance.

Preparation of salinomycin-loaded micelles and the effects on cancer stem cells in vitro / 中国药学杂志

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.

The Analysis of Malignant Characteristics of Side Population Cells in Patients with Cervical Cancer / 天津医药

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.

Sorting of side population cells from breast cancer MCF-7 cell line and its biological characteristics / 中国基层医药

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.

Proportion and tumorigenetic characteristics of side population cells in gastric cancer cell lines / 中华消化杂志

Objective To study the tumorigenetic characteristics of side population (SP) cells and their exsistence in gastric cancer cell lines and tissues.Methods Flow cytometry and the DNA-binding dye Hoechst 33342 staining were used to analyze sorted SP cells in 3 gastric cancer cell lines(SGC-7901,BCIC-823 and MKN28).SP cells and non-SP cells(main population cells)isolated from SGC-7901 cell line weresubcutaneously injected into 36 nude mice with 500,5000 or 50 000 cells per mouse,respectively.Thetumorigenity was observed 8 weeks after injection.The expression of ATP-binding cassette sub-family Gmember 2(ABcG2)mRNA in three gastric cell lines and its level in gastric cancer tissues were detected by real-time PCR and immunostaining.respectively.Results The proportion of SP cells was accounted for 1.0%in SGC-7901 cells and 1.3%in BGc-823 cells.No SP cell was found in MKN28 cells.As low as 500 SP cells or 50 000 non-SP cells could initiate tumors in mice.The expression of ABcG2 mRNA was higher in SGC-7901(O.162)and BGC-823(O.096)cell lines than that in MKN28 cell line(0.005).The value of AtCG2 mRNA/beta-aetin mRNA and protein in gastric cancer tissues was different from those in gastritis tissues.Condasimm SP cells have strong ability of tumorigenesis compared with non-SP cells.The expression of ABCG2 is found in gastric cancer tissues and part gastritis tissues.The more the SP cells in gastric cell lines,the higher the expression of ABCG2.

Identification of side population cells like cancer stem cell in human pancreatic cancer cell line SW1990 / 中华胰腺病杂志

Objective To isolate and identify side population (SP) cells like cancer stem cell from human pancreatic cancer cell line SW1990, for the purpose of further evaluation of their biological characteristics. Methods Cell suspension was stained with Hoechst 33342 and PI. Then SP cells were analyzed in the fluorescence activated cell sorter. Cell growth viability was measured by MTT. Stem cell marker CD133 was determined by flow cytometry. Cloning forming efficiency was determined by cloning plating. Expression of ABCG2 protein was detected by Western blot analysis. Results The proportion of SP cells was 2.7%, however it could be completely blocked by verapamil. 9 days later, the value of A492 of SP cells was 2.1, the cloning forming efficiency was (38.7 ± 6.8) % , the positive rate of CD133 was 69.63%, which were significantly higher than cells 0. 5, ( 15.5 ± 2.8)%, 16.71% of corresponding non-SP( P <0.05). The expression of ABCG2 in SP cells was significantly higher than that in non-SP cells. Conclusions SP cells existed in human pancreatic cancer cells SW1990.

Preliminary isolation and identifi cation of cancer stem-like cells in colon cancer cell line SW480 / 中国癌症杂志

Background and purpose:The theory of cancer stem cell offers us a new thought about tumors, more and more kinds of cancer stem cell were isolated and indentif ied from corresponding cancer tissue. Our aim was to investigate the content of side population cells in SW480 human colorectal cancer ce11 line and to enrich cancer stem- like cells in SW480 through serum-free medium (SFM) culture. Methods:The percentage of side population cells in human colorectal cancer cell line SW480 was detected with ? ow cytometry. SW480 cell line was cultivated in serum- free medium(SFM) supplemented with growth factors and the cancer stem-like cells reforming into ? oating spheres were isolated. The isolated cancer stem-like cells were identifi ed by limited-dilution assay, differentiation assay, self- renewal assay, and alternative cultivation assay. Results:The percentage of SP cells was 1.2% in SW480,In the absence of serum, a minority (0.54%-0.62%) of cancer stem-like cells in SW480 cells survived, proliferated and formed into the suspended tumor cell spheres. SW480 cancer stem-like cells possessed proliferative, self-renewal and differentiation potential, which were responsible for the ? oating tumor clone. Serum addition into SFM resulted in the proliferation of cancer stem-like cells; after several generations and alternated cultivation in SSM and SFM, cancer stem-like cells maintained their characteristics. Conclusions:SW480 cell line contains a tiny minority of SP cells with stem cell properties.The cancer stem-like cells in SW480 line can be maintained in SFM using a floating culture method.