Spontaneous Immortalization Research Articles

Transcriptome Profiling of Mouse Embryonic Fibroblast Spontaneous Immortalization: A Comparative Analysis.

Cell immortalization, a hallmark of cancer development, is a process that cells can undergo on their path to carcinogenesis. Spontaneously immortalized mouse embryonic fibroblasts (MEFs) have been used for decades; however, changes in the global transcriptome during this process have been poorly described. In our research, we characterized the poly-A RNA transcriptome changes after spontaneous immortalization. To this end, differentially expressed genes (DEGs) were screened using DESeq2 and characterized by gene ontology enrichment analysis and protein-protein interaction (PPI) network analysis to identify the potential hub genes. In our study, we identified changes in the expression of genes involved in proliferation regulation, cell adhesion, immune response and transcriptional regulation in immortalized MEFs. In addition, we performed a comparative analysis with previously reported MEF immortalization data, where we propose a predicted gene regulatory network model in immortalized MEFs based on the altered expression of Mapk11, Cdh1, Chl1, Zic1, Hoxd10 and the novel hub genes Il6 and Itgb2.

Characterization of latently infected EBV+ antibody-secreting B cells isolated from ovarian tumors and malignant ascites.

Intra-tumoral B cells mediate a plethora of immune effector mechanisms with key roles in anti-tumor immunity and serve as positive prognostic indicators in a variety of solid tumor types, including epithelial ovarian cancer (EOC). Several aspects of intra-tumoral B cells remain unclear, such as their state of activation, antigenic repertoires, and capacity to mature into plasma cells. B lymphocytes were isolated from primary EOC tissue and malignant ascites and were maintained in cell culture medium. The stably maintained cell lines were profiled with flow cytometry and B cell receptor sequencing. Secreted antibodies were tested with a human proteome array comprising more than 21,000 proteins, followed by ELISA for validation. Originating tumor samples were used for spatial profiling with chip cytometry. Antibody-secreting B lymphocytes were isolated from the ovarian tumor microenvironment (TME) of four different EOC patients. The highly clonal cell populations underwent spontaneous immortalization in vitro, were stably maintained in an antibody-secreting state, and showed presence of Epstein-Barr viral (EBV) proteins. All originating tumors had high frequency of tumor-infiltrating B cells, present as lymphoid aggregates, or tertiary lymphoid structures. The antigens recognized by three of the four cell lines are coil-coil domain containing protein 155 (CCDC155), growth factor receptor-bound protein 2 (GRB2), and pyruvate dehydrogenase phosphatase2 (PDP2), respectively. Anti-CCDC155 circulating IgG antibodies were detected in 9 of 20 (45%) of EOC patients' sera. Tissue analyses with multiparameter chip cytometry shows that the antibodies secreted by these novel human B cell lines engage their cognate antigens on tumor cells. These studies demonstrate that within the tumor-infiltrating lymphocyte population in EOC resides a low frequency population of antibody-secreting B cells that have been naturally exposed to EBV. Once stably maintained, these novel cell lines offer unique opportunities for future studies on intratumor B cell biology and new target antigen recognition, and for studies on EBV latency and/or viral reactivation in the TME of non-EBV related solid tumors such as the EOC.

Establishment and Characterization of Continuous Satellite Muscle Cells from Olive Flounder (Paralichthys olivaceus): Isolation, Culture Conditions, and Myogenic Protein Expression.

Olive flounder (Paralichthys olivaceus) muscle satellite cells (OFMCs) were obtained by enzymatic primary cell isolation and the explant method. Enzymatic isolation yielded cells that reached 80% confluence within 8 days, compared to 15 days for the explant method. Optimal OFMC growth was observed in 20% fetal bovine serum at 28 °C with 0.8 mM CaCl2 and the basic fibroblast growth factor (BFGF) to enhance cell growth. OFMCs have become permanent cell lines through the spontaneous immortalization crisis at the 20th passage. Olive flounder skeletal muscle myoblasts were induced into a mitogen-poor medium containing 2% horse serum for differentiation; they fused to form multinucleate myotubes. The results indicated complete differentiation of myoblasts into myotubes; we also detected the expression of the myogenic regulatory factors myoD, myogenin, and desmin. Upregulation (Myogenin, desmin) and downregulation (MyoD) of muscle regulation factors confirmed the differentiation in OFMCs.

Generation and characterization of two immortalized dermal fibroblast cell lines from the spiny mouse (Acomys).

The spiny mouse (Acomys) is gaining popularity as a research organism due to its phenomenal regenerative capabilities. Acomys recovers from injuries to several organs without fibrosis. For example, Acomys heals full thickness skin injuries with rapid re-epithelialization of the wound and regeneration of hair follicles, sebaceous glands, erector pili muscles, adipocytes, and dermis without scarring. Understanding mechanisms of Acomys regeneration may uncover potential therapeutics for wound healing in humans. However, access to Acomys colonies is limited and primary fibroblasts can only be maintained in culture for a limited time. To address these obstacles, we generated immortalized Acomys dermal fibroblast cell lines using two methods: transfection with the SV40 large T antigen and spontaneous immortalization. The two cell lines (AcoSV40 and AcoSI-1) maintained the morphological and functional characteristics of primary Acomys fibroblasts, including maintenance of key fibroblast markers and ECM deposition. The availability of these cells will lower the barrier to working with Acomys as a model research organism, increasing the pace at which new discoveries to promote regeneration in humans can be made.

The spontaneous immortalization probability of mammalian cell culture strains, as their proliferative capacity, correlates with species body mass, not longevity

BackgroundThe Peto's paradox consists in the observation that individuals from long-lived and large animal species do not experience a higher cancer incidence, despite being exposed for longer time to the possibility of accumulating mutations and having more target cells exposed to the phenomenon. The existence of this paradox has been recently confirmed (Vincze et al., 2022). Concurrently, robust evidence has been published that longevity involves a convergent evolution of cellular mechanisms that prevent the accumulation of mutations (Cagan et al., 2022). It remains unclear which cellular mechanisms are critical to allow the evolution of a large body mass while keeping cancer at bay. MethodsAdding to existing data linking cellular replicative potential and species body mass (Lorenzini et al., 2005), we have grown a total of 84 skin fibroblast cell strains from 40 donors of 17 mammalian species and analyzed their Hayflick's limit, i.e., their senescent plateau, and eventual spontaneous immortalization escape. The correlation of immortalization and replicative capacity of the species with their longevity, body mass and metabolism has been assessed through phylogenetic multiple linear regression (MLR). ResultsThe immortalization probability is negatively related to species body mass. The new evaluation and additional data about replicative potential strengthen our previous observation, confirming that stable and extended proliferation is strongly correlated with the evolution of a large body mass rather than lifespan. ConclusionThe relation between immortalization and body mass suggests a need to evolve stringent mechanisms that control genetic stability during the evolution of a large body mass.

Continuous fish muscle cell line with capacity for myogenic and adipogenic-like phenotypes

Cell-cultivated fish offers the potential for a more ethical, sustainable, and safe seafood system. However, fish cell culture is relatively understudied in comparison to mammalian cells. Here, we established and characterized a continuous Atlantic mackerel (Scomber scombrus) skeletal muscle cell line (“Mack” cells). The cells were isolated from muscle biopsies of fresh-caught fish, with separate isolations performed from two distinct fish. Mack1 cells (cells from the first isolation) were cultured for over a year and subcultured over 130 times. The cells proliferated at initial doubling times of 63.9 h (± 19.1 SD). After a spontaneous immortalization crisis from passages 37–43, the cells proliferated at doubling times of 24.3 h (± 4.91 SD). A muscle phenotype was confirmed through characterization of muscle stemness and differentiation via paired-box protein 7 and myosin heavy chain immunostaining, respectively. An adipocyte-like phenotype was also demonstrated for the cells through lipid accumulation, confirmed via Oil Red O staining and quantification of neutral lipids. New qPCR primers (HPRT, PAX3B, MYOD1, MYOG, TNNT3A, and PPARG) were tailored to the mackerel genome and used to characterize mackerel cell genotypes. This work provides the first spontaneously immortalized fish muscle cell line for research, ideally serving as a reference for subsequent investigation.

Small RNA deep sequencing revealed microRNAs’ involvement in modulating cellular senescence and immortalization state

Unlike rodent cells, spontaneous immortalization of avian cells and human cells is a very rare event. According to patent publications and current literature, there are no more than 4 spontaneously immortalized chicken embryo fibroblast (CEF) cell lines established up to date. One of those cell lines is ADOL (Avian Disease and Oncology Laboratory) ZS-1 cell line, which was established by continuous passaging of the CEFs derived from the specific pathogen free (SPF) 0.TVB*S1 (commonly known as rapid feathering susceptible or RFS) genetic line of chickens. The RFS genetic line of chickens was developed and has been maintained on the SPF chicken farm of USDA-ARS facility, ADOL, in East Lansing, Michigan, which is known as one of a few lines of chickens that are free of any known avian endogenous virus genes. To explore potential roles that epigenetic factors may play in modulating cellular senescence processes and spontaneous immortalization state, total RNAs extracted from samples of the RFS primary CEFs, RFS CEFs reached the 21st passage, and the ZS-1 cells were subjected to small RNA sequencing. Collectively, a total of 531 miRNAs was identified in the 3 types of samples. In contrast to the primary CEF samples, 50 miRNAs were identified with significantly differential expression only in the 21st passage samples; a different subset of 63 differentially expressed miRNAs was identified only in the ZS-1 samples; the majority of differentially expressed miRNAs identified in both the 21st passage CEF and the ZS-1 samples were more or less directionally consistent. Gene Ontology analysis results suggested that the epigenetic factor, miRNAs, plays a role in modulating the cellular senescence and spontaneous immortalization processes through various bioprocesses and key pathways including ErbB and MAPK signaling pathways. These findings provided the experimental and bioinformatic evidence for a better understanding on the epigenetic factor of miRNAs in association with cellular senescence and spontaneous immortalization process in avian cells.

Spontaneous immortalization of chicken fibroblasts generates stable, high-yield cell lines for serum-free production of cultured meat.

Cellular agriculture could meet growing demand for animal products, but yields are typically low and regulatory bodies restrict genetic modification for cultured meat production. Here we demonstrate the spontaneous immortalization and genetic stability of fibroblasts derived from several chicken breeds. Cell lines were adapted to grow as single-cell suspensions using serum-free culture medium, reaching densities of 108 × 106 cells per ml in continuous culture, corresponding to yields of 36% w/v. We show that lecithin activates peroxisome proliferator-activated receptor gamma (PPARγ), inducing adipogenesis in immortalized fibroblasts. Blending cultured adipocyte-like cells with extruded soy protein, formed chicken strips in which texture was supported by animal and plant proteins while aroma and flavour were driven by cultured animal fat. Visual and sensory analysis graded the product 4.5/5.0, with 85% of participants extremely likely to replace their food choice with this cultured meat product. Immortalization without genetic modification and high-yield manufacturing are critical for the market realization of cultured meat.

Knockout of mutant TP53 in the HaCaT cells enhances their migratory activity

The HaCaT cell line represents the spontaneously immortalized non-carcinogenic human keratinocytes that are used as a model for studying the function of normal human keratinocytes. There are two TP53 alleles in the HaCaT cell genome, which comprise two gain-of-function (GOF) mutations acquired through spontaneous immortalization (mutTP53). Mutations result in the increased proliferation rate and violation of the stratification program. The study was aimed to assess the effects of the mutTP53 gene knockout on the HaCaT keratinocytes capability of proliferation and migration in the in vitro model of epidermal injury and regeneration (scratch test), and on the ability to form stratified epithelium in the organotypic epidermal model. To perform the scratch-test, cells were cultured until monolayer was formed, then the standardized injury was created. The organotypic model was obtained by growing keratinocytes in the polycarbonate membrane inserts with the pore size of 0.4 μm at the interface between the phases (air-liquid). It has been shown that the mutant TP53 gene knockout results in the increased migration capability of the HaCaT keratinocytes: in the HaCaT with the mutTP53 knockout, the defect closure occurred faster than in the appropriate group of the WT HaCaT (p < 0.05), on day three the defect size was 12% ± 3% and 66% ± 5% of the initial size. There is evidence that mutant TP53 in the HaCaT cells is a negative regulator of the laminin 5 expression (LAMC2 expression was 9.96 ± 1.92 times higher in the cells with the mutTP53 knockout, p < 0.05), however, this does not promote normalization of the program of epithelial differentiation and stratification followed by formation of the stratum corneum in the organotypic model.

Impact of p53 Knockout on Protein Data Set of HaCaT Cells in Confluent and Subconfluent Conditions

The immortalized keratinocytes, HaCaT, are a popular model for skin research (toxicity, irritation, allergic reactions, or interaction of cells). They maintain a stable keratinocyte phenotype and respond to keratinocyte differentiation stimuli. However, programs of stratification and expression of differentiation markers in HaCaT keratinocytes are aberrant. In HaCaT cells, there are two mutant p53 alleles (i.e., R282Q and H179Y) that contain gain-of-function (GOF) mutations resulting from spontaneous immortalization (mutp53). At the same time, mutp53 acts as a transcription factor and also affects the interaction of p63 protein with its transcription targets. Proteins of the p53 family are crucial for regulation of proliferation and differentiation processes in human keratinocytes, although the involvement of mutp53 in these processes is not fully clear. We present data sets obtained as a result of high-performance proteomic analysis of immortalized HaCaT keratinocytes with p53 knockout in two different states, subconfluent and confluent, which are characterized by different intensites of cell differentiation processes. To obtain the proteomic profiles of the cells, we applied LC-MS/MS measurements processed with MaxQuant software (version 1.6.3.4).

Establishment, characterization, and transfection potential of a new continuous fish cell line (CAM) derived from the muscle tissue of grass goldfish (Carassius auratus).

A new continuous fish cell line (CAM) has been successfully derived from the muscle tissues of grass goldfish, Carassius auratus. The primary cell cultures were initiated by incomplete trypsinization first and then explant culture in a Leibovitz-15 medium supplemented with 15% fetal bovine serum and 10% fish muscle extract. It was found that the CAM cells were very sensitive to trypsinization and needed to be sub-cultured at a low trypsin concentration of 0.0625% to be able to go through the crisis of spontaneous immortalization transformation, and afterward a total of five derivative cell strains were isolated from the original CAM cell line. This spontaneous immortalization transformation event was recorded successively at passages 44-47, beginning with a large-scale apoptosis and senescence and followed by mitosis arrest and re-activation, thus designated as cell strain CAM-44A, 44B, 45A, 44B, and 47A. Now both the CAM cell line and strains had been sub-cultured for more than 89 times and could be well cryopreserved in the growth medium containing 5% dimethylsulfoxide. Chromosome analysis and COI gene analysis had confirmed the grass goldfish origin of these CAM cells. Transfection potential analysis indicated that Lipofectamine LTX and Xfect were two suitable transfection reagents to be used in the gene delivery of CAM cells with a transfection efficiencies up to 11±6% and 8±3% in the CAM cell lines, respectively. Among the five cell strains, CAM-47A showed the highest transfection potential with a transfection efficiency up to 28 ± 5%. This work will provide a useful cell source for works on the cell-based artificial fish meat production and functional studies of fish myogenesis-related genes.

Establishment and characterization of a new spontaneously immortalized ER\u2212/PR\u2212/HER2+ human breast cancer cell line, DHSF-BR16

Invasive ductal carcinoma (IDC) constitutes the most frequent malignant cancer endangering women’s health. In this study, a new spontaneously immortalized breast cancer cell line, DHSF-BR16 cells, was isolated from the primary IDC of a 74-years old female patient, treated with neoadjuvant chemotherapy and disease-free 5-years after adjuvant chemotherapy. Primary breast cancer tissue surgically removed was classified as ER−/PR−/HER2+, and the same phenotype was maintained by DHSF-BR16 cells. We examined DHSF-BR16 cell morphology and relevant biological and molecular markers, as well as their response to anticancer drugs commonly used for breast cancer treatment. MCF-7 cells were used for comparison purposes. The DHSF-BR16 cells showed the ability to form spheroids and migrate. Furthermore, DHSF-BR16 cells showed a mixed stemness phenotype (i.e. CD44+/CD24−/low), high levels of cytokeratin 7, moderate levels of cytokeratin 8 and 18, EpCAM and E-Cadh. Transcriptome analysis showed 2071 differentially expressed genes between DHSF-BR16 and MCF-7 cells (logFC > 2, p-adj < 0.01). Several genes were highly upregulated or downregulated in the new cell line (log2 scale fold change magnitude within − 9.6 to + 12.13). A spontaneous immortalization signature, mainly represented by extracellular exosomes-, plasma membrane- and endoplasmic reticulum membrane pathways (GO database) as well as by metabolic pathways (KEGG database) was observed in DHSF-BR16 cells. Also, these cells were more resistant to anthracyclines compared with MCF-7 cells. Overall, DHSF-BR16 cell line represents a relevant model useful to investigate cancer biology, to identify both novel prognostic and drug response predictive biomarkers as well as to assess new therapeutic strategies.

Can permanent cell lines originate from low-grade astrocytomas: overgrowth of "glia-like" cells in pilocytic and fibrillary (diffuse) astrocytoma cultures.

Due inter alia to wide-spread cell lines cross-contamination it is not clear, which kind of normal or tumoral tissue give rise to permanent cell lines. Few permanent cell lines have been established from low-grade astrocytomas. However, recently some of these have been identified as being cross-contaminated with other cell lines. Morphology, cell growth and GFAP immunophenotype of low-grade astrocytomas were examined on 9 pilocytic and 15 fibrillary (diffuse) tissue cultures. GFAP-positive process-bearing cells were present in all the cultures, mainly during the first days in vitro (DIV). In pilocytic cultures, cells with hairy (piloid) processes were present. GFAP-positive cells completely disappeared by passages 3 to 5 and all the cultures contained only GFAP-negative "glia-like" cells, which underwent cellular senescence within passages 8 to 15. Key differences in the morphology and GFAP expression between the neoplastic astrocytes and normal "glia-like" cells allow the observation of perceptibly more rapid growth of normal cells in astrocytoma cultures. We caution that cultures prepared from macroscopically tumoral brain tissue may contain rapidly proliferating normal cells. Based on this and our previous studies in relation to the high percentage of cross-contaminated cell lines, we conclude that cells in low-grade astrocytoma cultures lack the capacity for spontaneous immortalization (Fig. 14, Ref. 15). Text in PDF www.elis.sk Keywords: pilocytic astrocytoma, fibrillary astrocytoma, "glia-like" cells, glioma cell lines, GFAP.

Abstract TP283: Phosphorylation of IRF5/4 by IRAK4/MyD88 Regulates Microglial Inflammatory Responses to Ischemia

Introduction: Interferon Regulatory Factors 5 and 4 (IRF5/4) have been suggested to play a determinant role in regulating pro-inflammatory (M1) or anti-inflammatory (M2) microglia/macrophage response. However, how IRF5/4 signaling are activated in these phagocytes has not been well understood. Our previous study has shown an increased level of phosphorylated-IRF4 in both the cytosolic and nuclear fraction of cultured microglial homogenates after ischemia, suggesting phosphorylation is important for IRF4 activation. Interleukin-1 receptor associated kinase 4 (IRAK4) and the adaptor protein MyD88 are the upstream signals of IRF5. In the present study we hypothesized that IRAK4/MyD88 phosphorylate IRF5/4 in ischemic microglia and trigger the translocation of IRF5/4 from the cytoplasm to the nucleus, to promote expression of inflammatory mediators. Methods: Spontaneously Immortalized (SIM)-A9 or primary microglia from C57BL/6 mice were cultured and exposed to oxygen-glucose deprivation (OGD) for 4 hours; after OGD the cells were reperfused overnight with glucose-containing medium in room air. Phosphorylation of IRF5/4 by IRAK4 was determined with IRAK4 inhibitor (ND-2158). The interaction between IRAK4/MyD88 with IRF5/4 and the nuclear translocation of phosphorylated-IRF5/4 were examined by immunocytochemistry (ICC) and co-immunoprecipitation (Co-IP)/Western Blots (WB). Production of inflammatory cytokines was measured by ELISA in the culture medium. Results: WB showed more robust nuclear p-IRF5 signals; ELISA found increased level of TNFα, IL-1β, and IL6 in OGD vs. normoxic microglia. A similar pattern was observed for p-IRF4 nuclear translocation but with moderately increased anti-inflammatory cytokine (IL-4 and IL-10) levels with OGD. Co-IP revealed a higher ratio of p-IRF5/4 over total IRF5/4 in the nuclear vs. cytosol fraction, and interactions of IRAK4/MyD88 with both IRFs. ND-2158 treatment led to decreased phosphorylation of IRF5/4 after OGD compared to the vehicle group. Conclusion: IRAK4/MyD88 complex phosphorylates microglial IRF5/4 which subsequently mediates the production of inflammatory cytokines after ischemia. Manipulation of IRF5/4 signaling potentially represents a novel therapeutic strategy for stroke.

Establishment of epithelial and fibroblast cell cultures and cell lines from primary renal cancer nephrectomies.

Renal cell carcinoma (RCC) is one of the most lethal urogenital cancers and effective treatment of metastatic RCC remains an elusive target. Cell lines enable the in vitro investigation of molecular and genetic changes leading to renal carcinogenesis and are important for evaluating cellular drug response or toxicity. This study details a fast and easy protocol of establishing epithelial and fibroblast cell cultures or cell lines concurrently from renal cancer nephrectomy tissue. The protocol involves mechanical disaggregation, collagenase digestion and cell sieving for establishing epithelial cells while fibroblast cells were grown from explants. This protocol has been modified from previous published reports with additional antibiotics and washing steps added to eliminate microbial contamination from the surgical source. Cell characterisation was carried out using immunofluorescence and quantitative polymerase chain reaction. Eleven stable epithelial renal tumour cell lines of various subtypes, including rare subtypes, were established with a spontaneous immortalisation rate of 21.6% using this protocol. Eight fibroblast cell cultures grew successfully but did not achieve spontaneous immortalisation. Cells of epithelial origin expressed higher expressions of epithelial markers such as pan-cytokeratin, cytokeratin 8 and E-cadherin whereas fibroblast cells expressed high α-smooth muscle actin. Further mutational analysis is needed to evaluate the genetic or molecular characteristics of the cell lines.

Short-term glioblastoma cultures may contain normal "glia-like" cells.

Currently used glioblastoma cultures have many disadvantages and are being replaced by short-term cultures. However, these may include normal brain cells. A comparative model of normal and glioma cultures is lacking. Asignificant contributory factor is because cultures from adult human brain contain small amounts of cells with glial phenotypes. The predominant population of flat or spindle shaped cells does not express glial markers and are often termed as "glia-like". Cryopreserved glioblastoma cultures from 28 bioptic samples were examined by immunofluorescence using antibodies to intermediate filaments (IF): glial fibrillary acidic protein (GFAP), cytokeratins (CK), nestin (Nes), vimentin (Vim) and neurofilaments (NF). In short-term glioblastoma cultures GFAP-positive cells occured at higher percentages in 3/28 cultures and in lower percentages in further 5 cultures. Subpopulation of nestin positive cells were observed in all cultures and CK-positive cells were found in 25/28 cultures. All cells in all cultures were positively stained only for vimentin and negatively for NF. Cells grew slowly in 5 cultures which showed early proliferation arrest between passages 7 to 8. Afurther 23 cultures showed growth arrest by passages 10 to 15. The presence of normal cells in short-term glioblastoma cultures may be caused by the infiltrative growth of these tumors. Our comparative analysis of morphological, growth and cytoskeletal properties revealed similarities between glioblastoma and normal brain cultures. In this study, the majority (28/30) of short-term glioblastoma showed limited life spans, similar to normal cells lacking spontaneous immortalization. The use of short-term glioblastoma cultures has two main problematic areas: cultures may contain a major subpopulation of normal "glia-like" cells; or they may contain the inital phases of spontaneously immortalized glioblastoma cells bearing properties of permanent cell lines (Tab. 1, Fig. 2, Ref. 19).

CAISMOV24, a new human low-grade serous ovarian carcinoma cell line

BackgroundThe spontaneous immortalization of primary malignant cells is frequently assigned to their genetic instability during in vitro culturing. In this study, the new epithelial ovarian cancer cell line CAISMOV24 was described and compared with its original low-grade serous ovarian carcinoma.MethodsThe in vitro culture was established with cells isolated from ascites of a 60-year-old female patient with recurrent ovarian cancer. The CAISMOV24 line was assessed for cell growth, production of soluble biomarkers, expression of surface molecules and screened for typical mutations found in serous ovarian carcinoma. Additionally, comparative genomic hybridization was employed to compare genomic alterations between the CAISMOV24 cell line and its primary malignant cells.ResultsCAISMOV24 has been in continuous culture for more than 30 months and more than 100 in vitro passages. The cell surface molecules EpCAM, PVR and CD73 are overexpressed on CAISMOV24 cells compared to the primary malignant cells. CAISMOV24 continues to produce CA125 and HE4 in vitro. Although the cell line had developed alongside the accumulation of genomic alterations (28 CNV in primary cells and 37 CNV in CAISMOV24), most of them were related to CNVs already present in primary malignant cells. CAISMOV24 cell line harbored KRAS mutation with wild type TP53, therefore it is characterized as low-grade serous carcinoma.ConclusionOur results corroborate with the idea that genomic alterations, depicted by CNVs, can be used for subtyping epithelial ovarian carcinomas. Additionally, CAISMOV24 cell line was characterized as a low-grade serous ovarian carcinoma, which still resembles its primary malignant cells.

Cytoplasmic E3 ubiquitin ligase CUL9 controls cell proliferation, senescence, apoptosis and genome integrity through p53.

CUL9 is a member of the cullin family of E3 ubiquitin ligases, and it localizes predominantly in the cytoplasm. Deletion of Cul9 in mice results in increased DNA damage, widespread aneuploidy, spontaneous tumor development, accelerated Eμ-Myc-induced lymphomagenesis, and susceptibility to carcinogenesis. CUL9 binds to p53 and causes cell apoptosis when ectopically expressed. Whether the function of CUL9 in maintaining genomic integrity and suppressing tumorigenesis is linked to p53 has not been genetically tested. Here, we report that deletion of CUL9 in human cells results in attenuated p21 induction and impaired cellular response to DNA damage. We show that disruption of Cul9-p53 binding in mouse embryo fibroblasts (MEFs) by a knock-in mutation in Cul9 (Δp53) increases S-phase cell population, accumulates DNA damage during DNA replication, and decreases apoptosis to both endogenous and exogenous DNA-damaging agents. The extent of these alterations in Cul9Δp53 MEFs is indistinguishable to those seen in Cul9-/- MEFs and comparable to those seen in p53-/- MEFs. Deletion of CUL9 in p53 null cells does not lead to further increase of DNA damages. Both Cul9-/- and Cul9Δp53 MEFs proliferate faster and undergo spontaneous immortalization while retaining both Arf and p53. These results demonstrate that the functions of CUL9 in regulating cell proliferation and maintaining genomic integrity are mainly mediated by p53, and that CUL9 is a critical p53 activator.

Invitromatics, invitrome, and invitroomics: introduction of three new terms for in vitro biology and illustration of their use with the cell lines from rainbow trout.

The literature on cell lines that have been developed from rainbow trout (RT) (Oncorhynchus mykiss) is reviewed to illustrate three new terms: invitromatics, invitrome, and invitroomics. Invitromatics is defined as the history, development, characterization, engineering, storage, and sharing of cell lines. RT invitromatics differs from invitromatics for humans and other mammals in several ways. Nearly all the RT cell lines have developed through spontaneous immortalization. No RT cell line undergoes senescence and can be described as being finite, whereas many human cell lines undergo senescence and are finite. RT cell lines are routinely grown at 18-22°C in free gas exchange with air in basal media developed for mammalian cells together with a supplement of fetal bovine serum. An invitrome is defined as the grouping of cell lines around a theme or category. The broad theme in this article is all the cell lines that have ever been created from O. mykiss, or in other words, the RT invitrome. The RT invitrome consists of approximately 55 cell lines. These cell lines can also be categorized on the basis of their storage and availability. A curated invitrome constitutes all the cell lines in a repository and for RT consists of 11 cell lines. These consist of epithelial cell lines, such as RTgill-W1, and fibroblast cell lines, such as RTG-2. RTG-2 can be purchased from a scientific company and constitutes the commercial RT invitrome. Cell lines that are exchanged between researchers are termed the informally shared invitrome and for RT consists of over 35 cell lines. Among these is the monocyte/macrophage cell line, RTS11. Cell lines whose existence is in doubt are termed the zombie invitrome, and for RT, approximately 12 cell lines are zombies. Invitroomics is the application of cell lines to a scientific problem or discipline. This is illustrated with the use of the RT invitrome in virology. Of the RT invitrome, RTG-2 was the most commonly used cell line to isolate viruses. Fifteen families of viruses were studied with RT invitrome. RT cell lines were best able to support replication of viruses from the Herpesviridae, Iridoviridae, Birnaviridae, Togaviridae, and Rhabdoviridae families.

Gene regulatory network underlying the immortalization of epithelial cells

BackgroundTumorigenic transformation of human epithelial cells in vitro has been described experimentally as the potential result of spontaneous immortalization. This process is characterized by a series of cell–state transitions, in which normal epithelial cells acquire first a senescent state which is later surpassed to attain a mesenchymal stem–like phenotype with a potentially tumorigenic behavior. In this paper we aim to provide a system–level mechanistic explanation to the emergence of these cell types, and to the time–ordered transition patterns that are common to neoplasias of epithelial origin. To this end, we first integrate published functional and well–curated molecular data of the components and interactions that have been found to be involved in such cell states and transitions into a network of 41 molecular components. We then reduce this initial network by removing simple mediators (i.e., linear pathways), and formalize the resulting regulatory core into logical rules that govern the dynamics of each of the network components as a function of the states of its regulators.ResultsComputational dynamic analysis shows that our proposed Gene Regulatory Network model recovers exactly three attractors, each of them defined by a specific gene expression profile that corresponds to the epithelial, senescent, and mesenchymal stem–like cellular phenotypes, respectively. We show that although a mesenchymal stem–like state can be attained even under unperturbed physiological conditions, the likelihood of converging to this state is increased when pro–inflammatory conditions are simulated, providing a systems–level mechanistic explanation for the carcinogenic role of chronic inflammatory conditions observed in the clinic. We also found that the regulatory core yields an epigenetic landscape that restricts temporal patterns of progression between the steady states, such that recovered patterns resemble the time–ordered transitions observed during the spontaneous immortalization of epithelial cells, both in vivo and in vitro.ConclusionOur study strongly suggests that the in vitro tumorigenic transformation of epithelial cells, which strongly correlates with the patterns observed during the pathological progression of epithelial carcinogenesis in vivo, emerges from underlying regulatory networks involved in epithelial trans–differentiation during development.