Retention of differentiated function in dispersed cell culture

Progranulin/GP88, A Complex and Multifaceted Player of Tumor Growth by Direct Action and via the Tumor Microenvironment

Investigation of the role of progranulin/GP88 on the proliferation and survival of a wide variety of cells has been steadily increasing. Several human diseases stem from progranulin dysregulation either through its overexpression in cancer or its absence as in the case of null mutations in some form of frontotemporal dementia. The present review focuses on the role of progranulin/GP88 in cancer development, progression, and drug resistance. Various aspects of progranulin identification, biology, and signaling pathways will be described. Information will be provided about its direct role as an autocrine growth and survival factor and its paracrine effect as a systemic factor as well as via interaction with extracellular matrix proteins and with components of the tumor microenvironment to influence drug resistance, migration, angiogenesis, inflammation, and immune modulation. This chapter will also describe studies examining progranulin/GP88 tumor tissue expression as well as circulating level as a prognostic factor for several cancers. Due to the wealth of publications in progranulin, this review does not attempt to be exhaustive but rather provide a thread to lead the readers toward more in-depth exploration of this fascinating and unique protein.

Regulated galactolipid synthesis and cell surface expression in Schwann cell line D6P2T

Clonal cell line D6P2T, subcloned from an ethylnitrosourea-induced tumor line D6 of the rat peripheral nervous system, has been characterized with particular attention to galactolipid metabolism. Galactosylcerebroside and sulfatide synthesis and expression on the cell surface are highly regulated in D6P2T cells by mechanisms involving serum- and cyclic AMP-mediated pathways. These cells also express 2',3'-cyclic nucleotide 3'-phosphohydrolase (Wolfgram protein W1a) and laminin. In contrast, myelin basic protein and antigen HNK-1 were not detected. Line D6P2T appears to be a semi-differentiated Schwann cell model, which offers interesting possibilities for studies of galactolipid synthesis, transport, and sorting.

An improved basal medium for Y-1 mouse adrenal cortex tumor cells in culture. 2. Stability of steroidogenic pathway and chromosome number

Y-1 cells were passaged weekly for 6 wk in MACT IV medium without a period of adaptation to this basal medium that requires 1% dialyzed fetal bovine serum as a supplement. The steroid pathway and chromosome number, reported earlier for this cell line under culture conditions that used much higher concentrations of nondialyzed sera, remained stable despite dialysis and reduction of the fetal bovine serum to 1%.

Toxicology investigations with cell culture systems

This review concerns some of the cell culture systems that are most frequently used in toxicology investigations. In particular, it sets out to evaluate the effectiveness of these cell culture systems in assessing the toxic potential of chemicals. Metabolic studies and general and specific toxicology investigations are highlighted. Specific toxicology investigations relate to the effects of the tests substances on the highly specialized functions typical of the cell systems chosen. The general toxicology investigations include most of the other studies where differentiated or undifferentiated cells have been used to evaluate the effects of the tested substances on common basic biochemical processes essential for life. Lastly, we have attempted to focus attention on the most promising applications of cell cultures in toxicology studies for the near future and to identify those areas where further research is needed. Because of the several excellent reviews that already exist, we have decided not to consider cell cultures utilized in screening potential mutagens and carcinogens. We have also excluded investigations of drug therapeutic effects and action mechanisms of drugs.

The modulation of neurotransmitter synthesis by steroid hormones and insulin

Glucocorticoids stimulate tyrosine hydroxylase activity and catecholamine synthesis, while markedly inhibiting acetylcholine synthesis and storage in the a clone of sympathetic nerve-like cells. Nerve growth factor enhances the effect of glucocorticoids on tyrosine hydroxylase. The steroid effect is specific for glucocorticoids, since 11-desoxycortisol, testosterone, and estradiol-17 beta do not reproduce the effects of hydrocortisone and dexamethasone. Concomitant with the shift in neurotransmitter synthesis, there is an increase in the mean diameter of intracellular dense core vesicles. In contrast to glucocorticoids, insulin increases the specific activity of choline acetyltransferase through the interaction with typical insulin receptors. Insulin does not, however, alter the morphology of the cells, nor does it block the morphological response of the cells to nerve growth factor.

Scanning electron microscopy of induced cell rounding of mouse adrenal cortex tumor cells in culture

The surface topologies of mouse adrenal cortex tumor cells of primary or clonal origin grown as monolayer cell cultures were observed by scanning electron microscopy following their exposure to substances that effect steroid release and/or cell rounding. ACTH induced cell rounding with a concomitant profuse development of fine microvilli in a non-synchronously dividing cell population. This was less pronounced with other steroidogenic substances and absent in EGTA or trypsin-treated cells. Morphological alterations occurred most rapidly with cAMP and least rapidly with dbcAMP. The rapid development of fine microvilli with ACTH is proposed to be a specific hormone mediated response.

Serial cultivation of strains of human epidermal keratinocytes: the formation of keratinizing colonies from single cells

Human diploid epidermis epidermal cells have been successfully grown in serial culture. To initiate colony formation, they require the presence of fibroblasts, but proliferation of fibroblasts must be controlled so that the epidermal cell population is not overgrown. Both conditions can be achieved by the use of lethally irradiated 3T3 cells at the correct density. When trypsinized human skin cells are plated together with the 3T3 cells, the growth of the human fibroblasts is largely suppressed, but epidermal cells grow from single cells into colonies. Each colony consists of keratinocytes ultimately forming a stratified squamous epithelium in which the dividing cells are confined to the lowest layer(s). Hydrocortisone is added to the medium, since in secondary and subsequent subcultures it makes the colony morphology more oderly and distinctive, and maintains proliferation at a slightly greater rate. Under these culture conditions, it is possible to isolate keratinocyte clones free of viable fibroblasts. Like human diploid fibroblasts, human diploid keratinocytes appear to have a finite culture lifetime. For 7 strains studied, the culture lifetime ranged from 20-50 cell generations. The plating efficiency of the epidermal cells taken directly from skin was usually 0.1-1.0%. On subsequent transfer of the cultures initiated from newborns, the plating efficiency rose to 10% or higher, but was most often in the range of 1-5% and dropped sharply toward the end of their culture life. The plating efficiency and culture lifetime were lower for keratinocytes of older persons.

The uptake of GABA by clonal nerve glia

A number of clonal nerve and glial cell lines are able to accumulate exogenous GABA. The ability of the cells to concentrate GABA is dependent upon external calcium, while the uptake process is sodium dependent and temperature sensititive. GABA uptake by the cell lines is specific with respect to analogue inhibition, but this specificity is different from that observed in brain slices. It is, however, similar to that of glia in the rat sensory ganglia. Although clonal muscle cells can concentrate GABA to a limited extent, a number of other differentiated cells cannot.

In vitro differentiation of a mouse neuroblastoma

Mouse tumor C1300 has been established in tissue culture. The cells have a round cell morphology in both the subcutaneous tumor and in suspension culture. However, when given a surface on which to attach, they send out processes up to 3 mm in length and assume the morphology of mature neurons. The attached cells are stained by the Bodian silver procedure for neurons, whereas the cells grown in suspension are not. Electron microscopy reveals that the attached cells contain neurofilaments, neurotubules, and densecore vesicles indicative of nerve fibers. Both free-floating and attached cells have tyrosine hydroxylase activity characteristic of sympathetic nervous tissue. Apparently cell attachment can induce morphological differentiation from an anaplastic round cell to a cell which has many properties of a mature neuron.

Establishment of a clonal strain of hepatoma cells which secrete albumin

A clonal strain of epithelial cells (designated MH(1)C(1)) has been established from the transplantable Morris hepatoma No. 7795. The cells have maintained distinctive morphology throughout more than 20 subcultures (split 1:5) at 2- to 4-week intervals in supplemented Ham's F 10 medium. They contain many highly refractile, round, cytoplasmic bodies which stain bright red with Oil Red O. The population doubling time was 2 wk when the clonal strain was first established. It has gradually decreased to 1 wk. The cells synthesize rat serum albumin and secrete it into the culture medium as determined immunologically by microcomplement fixation and double diffusion. Albumin secretion (3-6 microg albumin/mg cell nitrogen/24 hr) occurs throughout the logarithmic phase of cell proliferation and has not diminished during serial propagation since the strain was initiated 15 months ago.