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The Expression of SPARC in Human Urothelial Cells ( UROtsa ) Exposed to or Malignantly Transformed by Cadmium or Arsenite. Jennifer Larson Doctoral Candidate University of North Dakota October 5, 2011. Outline. Background Info Purpose Methods Results Conclusions Future directions.
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The Expression of SPARC in Human Urothelial Cells (UROtsa) Exposed to or Malignantly Transformed by Cadmium or Arsenite Jennifer Larson Doctoral Candidate University of North Dakota October 5, 2011
Outline • Background Info • Purpose • Methods • Results • Conclusions • Future directions
Bladder Cancer • Transitional cell carcinoma of the bladder is the 9th most common cancer worldwide and the 4th in U.S (Bischoff & Clark, 2010) • Highest cost per patient of all cancers (Sullivan et al., 2010; Jacobs et al., 2010) • Bladder cancer was the first cancer in which industrial carcinogens were found to play the major role in disease causation • Link between exposure to aromatic amines and development of bladder cancer in factory workers (Rehn, 1895) • Cd⁺² and As⁺³ are human carcinogens (IARC, 1993; IARC, 1980)and linked to the development of bladder cancer(Steinmaus et al., 1994 & 2000) • Association between cigarette smoking and bladder cancer • 2-4 times increased risk (Clavel et al., 1989; Morrison et al., 1984; Silverman et al., 1992)
UROtsa Cell Line • Derived from the urothelium lining the ureter of a 12 year-old female. • Immortalized with SV40 large T-antigen (Perzoldtet al., 1995) • Cd⁺² and As⁺³ are able to cause the malignant transformation of UROtsa cells (Sens et al., 1994 & 2000) • Generated 7 different Cd+2 & 6 different As+3 cell lines. UROtsa Parent UROtsa Cd⁺² UROtsa As⁺³ Sens et al. Toxicological Sciences (2004) • UROtsa parent cells are non-tumorigenic: • Do not grow in soft agar • No not form tumors in nude mice • Transformed cell lines are tumorigenic: • Grow in soft agar • Form tumors in nude mice
SPARC • Secreted Protein, Acidic and Rich in Cysteine • Also known as: Osteonectin & BM-40 • Belongs to the Matricellular group of proteins • Secreted macromolecules that interact with cell-surface receptors, ECM, and/or growth factors and proteases, but do NOT have structural roles • Known to bind to structural matrix proteins • Collagen and Vitronectin • Found in tissues undergoing repair/remodeling (Salonen et al. 1990) • Upregulated during embryological development (Sage et al., 1989) • Other matricellular proteins include: • Thrombosponbin 1 & 2 • Tenascin C & X • Osteopontin • CTGF • Testican 1, 2, & 3 (SPARC-related protein) • Hevin (SPARC-related protein)
SPARC • 3 General functions of SPARC: • 1. De-adhesion: • Exogenous SPARC inhibits cell spreading and cell attachment (Sage et al. 1989) • Disassemble focal adhesions (Murphy-Ullrich et al. 1995, Murphy-Ullrich 2001) • Reorganizes actin stress fibers to periphery of cell (Murphy-Ullrich et al. 1995) • May play a role in cell migration • 2. Anti-proliferation: • Cell cycle inhibitor (Funk & Sage 1991, 1993; Sage et al. 1995) • Promoted prostate cancer cell migration (De et al. 2003) and stimulated fibroblasts during myocardial infraction (Wu et al. 2006) • May play a role in cell migration • 3. Regulation of ECM & growth factors: • Binds to many ECM components (Brekken & Sage 2000) • Known activator of MMP-2 (Tremble et al. 1993) • Regulates PDGF, VEGF, & TGF-β1 expression(Raines et al, 1992, Kuppricon et al. 1998, Abe et al. 2004, Hasselaar & Sage 1992, Lane & Sage 1994) • After exogenous treatment, capable of inducing the expression of SPARC • May play a role in the progression of metastatic tumors
Purpose • To determine the role SPARC plays in the formation and progression of bladder cancer.
SPARC Expression in UROtsa Cell Lines & Normal Bladder Tissue • Larson et al 2010
SPARC Expression in Normal and Cancerous Bladder Tissue Normal Bladder Tissue High Grade Carcinoma • Larson et al 2010
SPARC Expression after Treatment with MS-275 & 5-AZC • Possible role of epigentic modification? • 24, 48, and 72h treatment • 48h shown • MS-275 is a histonedeacetylase inhibitor • Prevents acetyl groups from being removed from histones • 5-Aza-2’-deoxycytidine (5-AZC) is a methylation inhibitor • Inhibits the methylation of histones • Conclusion: No change in SPARC expression • Larson et al 2010
SPARC Expression after Drug Combination Treatment • Treatment with both MS-275 & 5-AZC for 72hrs • Conclusion: No change in SPARC expression • Larson et al 2010
SPARC Expression after Treatment with As⁺³ & Cd⁺² • Larson et al 2010
Summary: SPARC Expression • Moderate SPARC expression in Normal Tissue • Low or undetectable SPARC expression in Cancerous/Tumor Tissue • SPARC expression does not appear to be regulated epigenetically in our system • SPARC mRNA and protein expression decreases with increasing concentrations of As3+ and Cd2+
SPARC Transfection • 4 cell lines were chosen for stable transfection of SPARC: As#3, As#6, Cd#1, Cd#4 • All cell lines were characterized: • mRNA • Protein • Secretion of SPARC protein • Growth • Migration
SPARC Transfection • 4 cell lines were chosen for stable transfection of SPARC: As#3, As#6, Cd#1, Cd#4
SPARC Expression within Cultured Media • All cells were grown in Serum Free growth media • Media was harvested, centrifuged, and filtered • Protein was precipitated from growth media • Loaded equal total protein per lane • SPARC transfected cell lines had similar staining • SPARC expression does not appear to be matrix incorporated
Growth: MTT • Cao et al 2010; Somjiet al 2010
Migration • Wound/Scratch assay: • Cells were grown to confluence • Conditions: Untx or treated with Mitomycin C (MMC) for 2h • Scratch performed with 200ul pipette tip • Cells were rinsed with PBS 2x’s • Pictures taken at 0h and 24h • MTT performed to determine cell viability • Determine best concentration of MCCto prevent cell death • Performed in duplicate
Migration • Wound/Scratch assay:
Migration • Transwell Migration assay: • Top chamber = 2.4 x 105 cells/ml in serum free media • Bottom chamber = 1.5% fetal calf serum • 8h incubation for migration • Count total number of cells on insert • Remove cells from top of insert and count remaining • Total of 20 fields per insert, performed in duplicate
Migration • Transwell Migration assay: * * * * * ** **
Conclusions • Expression of SPARC is not epigenetically regulated in our system • SPARC expression decreased with treatment with Cd2+ & As3+ • SPARC tranfections: • Secrete SPARC into media • 2 transfected cell lines had decreased migration
Future Directions • Assess the ability of SPARC transfected cell lines to form tumors in nude mice • Tumor size • Subcutaneous vs. intraperitoneal tumor formation • Expression of SPARC in tumor • Assess the structural differences of SPARC between UROtsa Parent and transfected cell lines • Glycosylation • Post-translational modifications • Characterization of the promoter elements that turn off SPARC expression with treatment of Cd2+ & As3+
Acknowledgements • Dr Jane Dunlevy • Holly Hewitt • Dr Don Sens • Dr Mary Ann Sens • Dr SeemaSomji • Dr Scott Garrett • Dr XuDong Zhou
SPARC • First identified as the most abundant non-collagenous component of bone (Termine et al.1981) • Highly conserved among different species • Human gene has 92% homology with mice • Predicted molecular mass of 32,511 Daltons • Secreted form of the protein migrates at 43kD on SDS-PAGE • Due to addition of carbohydrates (Sage et al. 1984) Bradshaw & Sage 2001
SPARC Expression in Mouse Heterotransplants • Larson et al 2010
SPARC Expression in Cancerous Tissue • Tumor Promoter: • Increased expression of SPARC • Brain: Glioblastomas, Astrocytomas, Meningioma • Breast: Invasive ductal carcinoma • Lung: NSCLC, squamous cell carcinoma, adenocarcinoma • Pancreas: Pancreatic ductal adenocarcinoma • Skin: Melanoma • Tumor Suppressor: • Decreased expression of SPARC • Brain: Neuroblastoma • Ovary: carcinoma • Lung: NSCLC & SCLC • Pancreas: PDAC • Skin: Melanoma • Uterus: Cervical & endometrial carcinoma
Epigenetic Regulation of SPARC • Ovarian cancer: • Treatment with the demethylating agent 5-aza-2'-deoxycytidine (5-AZC) rescued SPARC mRNA and protein expression in 9 ovarian cancer cell lines • 1 cell line showed a significant increase in SPARC mRNA after TSA treatment, histonedeacetylase inhibitor (Socha et al. 2009) • Colon cancer: • Induction of SPARC was observed in 5 of the 7 cell lines after 5-AZC treatment (Yang et al. 2007) • Non-small cell lung cancer (NSCLC): • SPARC expression was restored after 5-AZC treatment in all 11 NSCLC cell lines (Suzuki et al. 2005) • Pancreatic adenocarcinoma: • SPARC mRNA expression was restored in seven 7 of 8 cell lines after 5-AZC treatment • SPARC expression was not restored 1 cell line after 5-AZC treatment did not restore the SPARC expression. • Treatment with an HDAC inhibitor TSA or with a combination of 5-AZC and TSA did not induce SPARC expression (Sato et al. 2003)