Project description:Colorectal cancer (CRC) has the third highest incidence and mortality rates among the US population. According to the most recent concept of carcinogenesis, human tumors are organized hierarchically, and the top of this hierarchy is occupied by malignant stem cells, or cancer stem cells (CSCs), which possess unlimited self-renewal and tumor-initiating capacities and high resistance to conventional anticancer therapies. To reflect the complexity and diversity of human tumors and to provide clinically and physiologically relevant in vivo and in vitro models, a large banks of well characterized patient-derived low-passage cell lines, and especially CSC-enriched cell lines are urgently needed. Using RNA-Seq, we have performed a functional genomic analysis in tumor-initiating fractions of CR4 (small) cells grown adherent to type I collagen versus grown as 3D spheroids, in comparison to the bulk tumor cells (long and dychotomized cells) grown under standard culture conditions.
Project description:Gene expression profiling of side population cells (SP) and CD146+ cells from primary human osteosarcoma. We aimed to identify genes that differentially regulated between the tumor propagating cells and the bulk tumor cells.
Project description:Sox2 is required to maintain osteosarcoma cell tumor initiation.Knockdown of Sox2 leads tpo loss of tumorigenic properties. To examine gene expression changes upon Sox2 knockdown, we performed microarray analysis on mouse osteosarcoma cells expressing scrambled or Sox2shRNA. We found that genes upregulated upon Sox2 knockdown included osteoblast diffrentiation genes and genes down regulated included cell cycle and RNA processing genes as well as YAP-TEAD target genes. The Hippo pathway has a profound tumor suppressive role in cancer by restraining the strong growth-promoting function of YAP. We have previously shown that the stem cell transcription factor Sox2 maintains the tumorigenicity of osteosarcoma cancer stem cells (CSCs). In this report, we describe that Sox2 maintains stemness by antagonizing the Hippo pathway via direct repression of Hippo activators, Nf2 (Merlin) and WWC1 (Kibra), thereby leading to exaggerated YAP function. YAP is potently oncogenic in osteosarcoma and its depletion sharply reduces the tumorigenic CSC fraction. Low Nf2, low WWC1, and high YAP expression mark the CSC fraction of the tumor population, while the more differentiated fraction has high Nf2, high WWC1 and reduced YAP expression. This Sox2-Hippo axis is conserved and also operates in other Sox2-dependent cancers such as glioblastomas. We propose that disruption of YAP transcriptional activity reduces CSCs and could be a therapeutic strategy for Sox2- dependent tumors. Gene expression of 482 mouse lines mOS482 were analyzed by microarray. 3 replicates each of scrambled and Sox2shRNA were processed and hybridized
Project description:Ovarian cancer (OC) displays the highest mortality among gynecological tumors, mainly due to early peritoneal dissemination, the high frequency of tumor relapse following primary debulking and the development of chemoresistance. All these events are thought to be initiated and sustained by a subpopulation of neoplastic cells, termed ovarian cancer stem cells (OCSC), that are endowed with self-renewing and tumor-initiating properties. This implies that interfering with OCSC function should offer novel therapeutic perspectives to defeat OC progression. To this aim, a better understanding of the molecular and functional makeup of OCSC in clinically relevant model systems is essential. We have profiled the transcriptome of OCSC vs. their bulk cell counterpart from a panel of patient-derived OC cell cultures. This revealed that Matrix Gla Protein (MGP), classically known as a calcification-preventing factor in cartilage and blood vessels, is markedly enriched in OCSC. Functional assays showed that MGP confers several stemness-associated traits to OC cells, including a transcriptional reprogramming. Patient-derived organotypic cultures pointed to the peritoneal microenvironment as a major inducer of MGP expression in OC cells. Furthermore, MGP was found to be necessary and sufficient for tumor initiation in OC mouse models, by shortening tumor latency and increasing dramatically the frequency of tumor-initiating cells. Mechanistically, MGP-driven OC stemness was mediated by the stimulation of Hedgehog signaling, in particular through the induction of the Hedgehog effector GLI1, thus highlighting a novel MGP/Hedgehog pathway axis in OCSC. Finally, MGP expression was found to correlate with poor prognosis in OC patients, and was increased in tumor tissue after chemotherapy, supporting the clinical relevance of our findings. Thus, MGP is a novel driver in OCSC pathophysiology, with a major role in stemness and in tumor initiation.
Project description:Sox2 is required to maintain osteosarcoma cell tumor initiation.Knockdown of Sox2 leads tpo loss of tumorigenic properties. To examine gene expression changes upon Sox2 knockdown, we performed microarray analysis on mouse osteosarcoma cells expressing scrambled or Sox2shRNA. We found that genes upregulated upon Sox2 knockdown included osteoblast diffrentiation genes and genes down regulated included cell cycle and RNA processing genes as well as YAP-TEAD target genes. The Hippo pathway has a profound tumor suppressive role in cancer by restraining the strong growth-promoting function of YAP. We have previously shown that the stem cell transcription factor Sox2 maintains the tumorigenicity of osteosarcoma cancer stem cells (CSCs). In this report, we describe that Sox2 maintains stemness by antagonizing the Hippo pathway via direct repression of Hippo activators, Nf2 (Merlin) and WWC1 (Kibra), thereby leading to exaggerated YAP function. YAP is potently oncogenic in osteosarcoma and its depletion sharply reduces the tumorigenic CSC fraction. Low Nf2, low WWC1, and high YAP expression mark the CSC fraction of the tumor population, while the more differentiated fraction has high Nf2, high WWC1 and reduced YAP expression. This Sox2-Hippo axis is conserved and also operates in other Sox2-dependent cancers such as glioblastomas. We propose that disruption of YAP transcriptional activity reduces CSCs and could be a therapeutic strategy for Sox2- dependent tumors.
Project description:An increased serum alkaline phosphatase concentration is known to be associated with a negative prognosis in canine and human osteosarcoma. To expand upon previous studies regarding the biological relevance of increased serum alkaline phosphatase as a negative prognostic factor, xenogeneic heterotopic transplants were performed using six canine primary osteosarcoma cell lines generated from patients with differing serum alkaline phosphatase concentrations (3 normal and 3 increased). Three of the six cell lines were capable of generating tumors and tumor formation was independent of the serum alkaline phosphatase status of the cell line. Microarray analysis identified 379 genes as being differentially-expressed between the tumorigenic and non-tumorigenic cell lines. Frizzled-6 was up-regulated to the greatest extent (7.78 fold) in tumorigenic cell lines compared to non-tumorigenic cell lines. Frizzled-6, a co-receptor for Wnt ligands has been associated with enhanced tumor-initiating cells and poor prognosis for other tumors. The increased expression of frizzled-6 was confirmed by QPCR and Western blot analysis. Additionally, the tumorigenic cell lines also had an increase in the percentage of side population cells compared to non-tumorigenic cell lines (5.89% versus 1.58%, respectively). There were no differences in tumorigenicity, frizzled-6, or percentage of side population cells noted between osteosarcoma cell lines generated from patients of differing serum alkaline phosphatase concentration. However, to our knowledge this is the first study to identified frizzled-6 as a possible marker of osteosarcoma cell populations with enhanced tumorigenicity and side population cells. Future work will focus on defining the role of frizzled-6 in osteosarcoma tumorigenesis and tumor-initiating cells. A total of six canine primary osteosarcoma cell lines were used in this study. Three cell lines were capable of forming tumors when transplanted into mice (tumorigenic) and three cell lines were not capable of forming tumors upon transplant into mice (non-tumorigenic). The gene expression data is from the primary cell lines, not the transplanted cells. There were no reference cell lines or controls used in this study.
Project description:CD133 (Prominin1) is pentaspan transmembrane glycoprotein expressed in several stem cell populations and cancers. Reactivity with an antibody (AC133) to a glycoslyated form of CD133 has been widely used for the enrichment of cells with tumor initiating activity in xenograph transplantation assays. We have found by fluorescence-activated cell sorting that increased AC133 reactivity in human embryonic stem cells, colon cancer and melanoma cells is correlated with increased DNA content and reciprocally, that the least reactive cells are in the G1/G0 portion of the cell cycle. Continued cultivation of cells sorted on the basis of high and low AC133 reactivity results in a normalization of the cell reactivity profiles indicating that cells with low AC133 reactivity can generate highly reactive cells as they resume proliferation. The association of AC133 with actively cycling cells may contribute to the basis for enrichment for tumor initiating activity. Keywords: Gene expression profiles of cells that express the AC133 epitiope of CD133 vs. AC133 negative cells