Role of Ectodermal-neural cortex 1 protein in human glioma progression, identification of a peptide internalized by human glioblastoma cells and development of an alternative method to generate growth curves of adherent cultures / Papel da proteína Ectodermal-neural cortex 1 (ENC1) na progressão de glioma humano, identificação de um peptídeo internalizado por células de glioblastoma humano e desenvolvimento de um método alternativo para gerar curvas de crescimento celular

Gliomas are the most common form of primary intracranial malignancy, among which astrocytomas are the most frequent. Ectodermal-cortex protein 1 (ENC 1), also known as Nuclear Restricted Protein/Brain (NRP/B), was first characterized as a protein which interacts with the cytoskeleton by binding to actin through Kelch-like domains, being related to neural fate specification during development of the nervous system. The first chapter of this thesis confirms ENC1 as a tumor suppression properties by a genomic edition approach, analyses ENC1 expression in a set of patient glioma samples and describes the correlation these data with patients survival and progression-free survival, concluding that ENC1 expression may constitute a biomarker for glioma aggressiveness. The second chapter refers to the identification and in vitro characterization of the LHTNELQ peptide, which was selected by the Phage Display method using human glioblastoma cells. This new peptide is able to be internalized by these cells and features as a new tool for the development of glioma therapeutics. The third chapter report an alternative method to generate growth curves of adherent cell cultures, which is based on the CFSE fluorescence decay over time. It is an alternative method to determine growth curves of cultured cells, with smaller variation among technical replicates than that of counting-based methods

Gliomas são a forma mais comum de malignidades primárias intracranianas, dentre os quais os astrocitomas são os mais frequentes. A proteína Ectodermal-neural cortex 1 (ENC1), também conhecida como Nuclear Restricted Protein/Brain (NRP/B), foi primeiramente caracterizada como uma proteína que interage com o citoesqueleto por meio de ligação à actina através de domínios Kelch-like, sendo relacionada com diferenciação neuronal durante o desenvolvimento do sistema nervoso. O primeiro capítulo desta tese descreve confirmação da capacidade supressora tumoral de ENC1 por abordagem de edição genômica, analisa a expressão de ENC1 em um conjunto de amostras de pacientes com gliomas e correlaciona esses dados com tempo de sobrevida geral e sobrevida livre de progressão tumoral nos pacientes, concluindo que a expressão de ENC1 pode ser utilizada como um biomarcador da agressividade do glioma. O segundo capítulo apresenta a identificação e caracterização in vitro do peptídeo LHTNELQ, que foi selecionado pela metodologia de Phage display utilizandose de células de glioblastoma humano. Este novo peptídeo é capaz de internalizar-se nestas células e figura como uma nova ferramenta para o desenvolvimento de estratégias terapêuticas para glioblastomas. No terceiro capítulo propõe-se um método alternativo para gerar curvas de crescimento celular de cultura aderente, o qual é baseado no decaimento da fluorescência do reagente CFSE ao longo do tempo. Tratase de um método alternativo para a determinação de curvas de crescimento de culturas aderentes, com menor variação entre as réplicas técnicas do que os métodos baseados em contagem das células

Effect of estrogen or progesterone combined with paclitaxel on human ovarian cancer cell growth and Drosha expression / 中华肿瘤杂志

<p><b>OBJECTIVE</b>To investigate the effect of estrogen (E2), progesterone(P4), and paclitaxel (taxol) on the growth of primary human ovarian cancer cells in vitro and the expression of Drosha.</p><p><b>METHODS</b>Human ovarian cancer cells were treated with estrogen, progesterone or in combination with paclitaxel in vitro. The inhibition rate of ovarian cancer cells was assessed by methyl thiazolyl tetrazolium (MTT) assay. Apoptosis rate and cell cycle were determined by FACS analysis. The relative abundence of Drosha expression was detected by real-time quantitative PCR (qRT-PCR) and Western blotting.</p><p><b>RESULTS</b>The inhibition rate of the estrogen group, progesterone group, paclitaxel group, E2(+)Taxol group, P4(+)Taxol group was (31.53 ± 8.21)%, (25.22 ± 15.50)%, (46.71 ± 4.25)%, (69.46 ± 3.71)%, and (47.35 ± 39.02)%, respectively, significantly higher than that of the control group (0%, P<0.05 for all). Relative to the ER (-) in ovarian cancer cells,Drosha mRNA expression level of estrogen group, progesterone group, paclitaxel group, E2(+) Taxol group,and P4(+)Taxol group was 1.62 ± 0.10,1.60 ± 0.10,1.75 ± 0.16,1.95 ± 0.20, and 1.53 ± 0.06, respectively, significantly higher than that of the control group (1.00, P<0.05 for all). Relative to the ER (+)in ovarian cancer cells,the Drosha mRNA expression level of estrogen group, progesterone group, paclitaxel group, E2(+)taxol group, and P4(+)Taxol group was 1.03 ± 0.14, 1.60 ± 0.09, 1.75 ± 0.16, 1.60 ± 0.10, 1.53 ± 0.06, respectively except estrogen group, significantly higher than that of the control group (1.00, P<0.05). Relative to the ER (-) in ovarian cancer cells, the Drosha protein expression levels of the control group, estrogen group, progesterone group, paclitaxel group, E2(+) taxol group, and P4(+) Taxol group were 0.25 ± 0.05, 0.87 ± 0.30, 0.85 ± 0.38, 1.30 ± 0.21, 1.75 ± 0.83, 1.62 ± 0.82, respectively, with a significant difference between the experimental groups and the control group (P<0.05). Relative to the ER(+)ovarian cancer cells, the Drosha protein expression levels in the estrogen group, progesterone group, paclitaxel group, E2(+) taxol group, and P4(+) taxol group, were 0.28 ± 0.16, 0.85 ± 0.38, 1.30 ± 0.21, 0.94 ± 0.18, and 1.62 ± 0.82, respectively except estrogen group, significantly higher than that of the control group (0.25 ± 0.05, P<0.05 for all).</p><p><b>CONCLUSIONS</b>Estrogen and progesterone in combination with paclitaxel can inhibit the growth of human ovarian cancer cells in vitro, and affect the cell apoptosis rate. Estrogen and taxol can alter the cell cycle. Estrogen and progesterone combined with paclitaxel show tumor suppressing or sensitizing effect through upregulated Drosha expression, and are associated with the estrogen receptor expression.</p>

Effect of cysteamine on cell growth and IgG[4] production in recombinant Sp2.0 cells

The manipulation of redox potential in secretory pathway by thiol reducing agents can be a strategy to improve the production levels of disulfide-bonded proteins including recombinant antibodies. Here we have studied the influence of cysteamine on viability and the production level of IgG[4] in Sp2.0 cells. For this purpose, the recombinant Sp2.0 cells producing an anti CD33 IgG[4], were subjected to different concentrations of cysteamine. At concentrations of 2, 4 and 5 mM cysteamine, the secreted levels of IgG[4] did not change significantly. However, in concentration of 7 mM cysteamine, a significant decrease was observed in IgG[4] levels which may indicate the cytotoxicity of this compound in higher concentrations. Our results show that the cysteamine treatment reduces the cell viability in a dose-dependent manner. Also it was observed that 2 mM cysteamine had no late effect on IgG4 production level and only at day 3, this concentration of cysteamine decreased the cell viability significantly. To test whether the addition of cysteamine can affect the expression level of protein disulfide isomerase, RT-PCR analysis was carried out. The results revealed that cysteamine does not affect the PDI transcription and expression level of IgG[4] in this type of recombinant cells

Effects of HMGA2 on malignant degree, invasion, metastasis, proliferation and cellular morphology of ovarian cancer cells

OBJECTIVE@#To analyze effects of high mobility group AT-hook 2 (HMGA2) on malignant degree, invasion, metastasis, proliferation and cellular morphology of ovarian cancer cells.@*METHODS@#Three methods were applied to observe the effect on HMGA2 expression in ovarian cancer cells and ovarian epithelial cells.@*RESULTS@#After the application of siRNA-HMGA2, number of T29A2-cell clones was decreased, there was significant difference compared with the negative control Block-iT. After application of let-7c, number of T29A2+ cell clones was decreased significantly, however, after the application of Anti-let-7, the number of clones restored, and there was no significant difference compared with the negative control group. After interference, the number of T29A2- cells which passed through Matrigel polycarbonate membrane were significantly lower than the negative control group. After the treatment of siRNA-HMGA2, let-7c and sh-HMGA2 respectively, growth and proliferation of T29A2-, T29A2+ and SKOV3 were slower, and the phenomenon was most obvious in SKOV3. Stable interference of HMGA2 induced mesenchymal-epithelial changes in the morphology of SKOV3-sh-HMGA2.@*CONCLUSIONS@#HMGA2 can promote malignant transformation of ovarian cancer cells, enhance cell invasion and metastasis, and promote cell growth and proliferation of ovarian cancer cells, which can cause ovarian cancer to progress rapidly and affect the quality of life.

Expression and function of Annexin II in lung cancer tissue

OBJECTIVE@#To explore the expression of Annexin II and its relationship with the cell differentiation, proliferation in lung cancer.@*METHODS@#RT-PCR and Western blot assays were used to detect the expression of Annexin II in lung cancer tissues and cell lines.@*RESULTS@#Annexin II was significantly up-regulated in lung cancer tissues, and in lung cancer cell lines, Annexin II had higher mRNA and protein expressions.@*CONCLUSIONS@#Annexin II is up-regulated in lung cancer, suggesting that the Annexin II has a potential value in the human lung cancer.

6 Paths of ERK5 signaling pathway regulate hepatocyte proliferation in rat liver regeneration.

Generally, extra-cellular-signal-regulated kinase 5 (ERK5) signaling pathway regulates many physiological activities, such as cell proliferation and cell differentiation. However, little is known about how ERK5 signaling pathway composed of 15 paths participates in regulating hepatocyte proliferation during liver regeneration (LR). In this study, to explore the influence ERK5 signaling pathway upon hepatocytes at gene transcription level, rat genome 230 2.0 array was used to detect expression changes of 75 related genes in isolated hepatocytes from rat regenerating liver. Bioinformatics and systems biology methods were applied to analyze the precise role of ERK5 signaling pathway in regulating hepatocyte proliferation during LR. Results showed that 62 genes were contained in the array and 22 genes were significantly changed. It was found that 6 paths were related to hepatocyte proliferation during rat LR. Among them, paths 3, 6 and 13 of ERK5 signaling pathway modulated cell cycle progression by decreasing the negative influence on ERK5 and paths 3, 4, 8 and 9 by reinforcing the positive influence on ERK5. In summary, the study shows that 22 genes and 6 paths of ERK5 signaling pathway participate in regulating proliferation of hepatocytes in rat LR.

Expression of RAS protein in glioma and its effect on the growth of human glioma cells / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To study the expression of RAS protein in human glioma tissues and its influence on tumor growth.</p><p><b>METHODS</b>RAS protein expression in glioma tissues was determined by immunohistochemical (IHC) staining. Subsequently, MTT cell proliferation assay, flow cytometry and Western blotting were used to assay U251 cells with reduced RAS expression.</p><p><b>RESULTS</b>The expression of RAS in glioma was increased and strongly correlated with pathological grade. Downregulation of RAS resulted in glioma cells growth suppression and increased apoptosis.</p><p><b>CONCLUSION</b>The expression level of RAS protein in human glioma was increased. Downregulation of RAS can inhibit glioblastoma cell growth through the RAS signal pathway.</p>

Mathematical model of tumor evolution in radiotherapy / 生物医学工程学杂志

The schemes of dose fractionation play an important role in tumor radiotherapy. We used mathematical methods to describe the process of tumor cells evolution during radiotherapy, trying to find how the schemes of dose fractionation affect tumor cells. In clinical radiobiology, linear-quadratic (LQ) model is frequently used to describe radiation effects of tumor cells. We integrated LQ model with effect of oxygen, and with the phenomenon of repopulation and reoxygenation in the theory of radiation biology. While we considered the disappearing progress of doomed cells in tumor, we established the mathematical model of tumor evolution in radiotherapy. We simulated some common treatment schedules, and studied the change role of tumor cells during radiotherapy. These results can serve for the optimization of dose fractionation scheme based on tumor radiobiological characteristics.

Study on antineoplastic effect of earthworm coelomic fluid in vitro / 中华实验和临床病毒学杂志

<p><b>OBJECTIVE</b>To explore the antineoplastic effect in vitro of earthworm coelomic fluid (ECF)on growth inhibition and its mechanism for the tumor cell lines Siha, SW480, Colo205 and PC12.</p><p><b>METHODS</b>MTT colorimetric assay, flow cytometry and morphological analysis were used to test its antitumor activity on tumor cell lines and normal cell line Cos7 in vitro.</p><p><b>RESULTS</b>ECF can inhibit the cell growth of Siha, SW480, Colo205, PC12 and Cos7. But different tumor cell lines showed different sensitivity.</p><p><b>CONCLUSION</b>EFC can significantly inhibit the proliferation of tumor cells in vitro by inducing tumor cells apoptosis.</p>

Fatal cases of Theileria annulata infection in calves in Portugal associated with neoplastic-like lymphoid cell proliferation

This study was carried out to investigate fifteen cases of acute lethal infection of calves (< or = 4 months of age) by the protozoan parasite Theileria (T.) annulata in the south of Portugal. Calves developed multifocal to coalescent nodular skin lesions, similar to multicentric malignant lymphoma. Infestation with ticks (genus Hyalomma) was intense. Theileria was seen in blood and lymph node smears, and T. annulata infection was confirmed by isolation of schizont-transformed cells and sequencing of hypervariable region 4 of the 18S rRNA gene. At necropsy, hemorrhagic nodules or nodules with a hemorrhagic halo were seen, particularly in the skin, subcutaneous tissue, skeletal and cardiac muscles, pharynx, trachea and intestinal serosa. Histologically, nodules were formed by large, round, lymphoblastoid neoplastic-like cells. Immunohistochemistry (IHC) identified these cells as mostly CD3 positive T lymphocytes and MAC387 positive macrophages. A marker for B lymphocytes (CD79alphacy) labeled very few cells. T. annulata infected cells in these nodules were also identified by IHC through the use of two monoclonal antibodies (1C7 and 1C12) which are diagnostic for the parasite. It was concluded that the pathological changes observed in the different organs and tissues were caused by proliferation of schizont-infected macrophages, which subsequently stimulate a severe uncontrolled proliferation of uninfected T lymphocytes.

Bio treatment protects rat marrow-derived mesenchymal stem cell culture against the TNF-a induced apoptosis

This study is an attempt to examine the anti apoptotic effects of BIO on rat MSC culture. Rat marrow primary cell culture was established and exposure groups were defined; cultures with 0.01, 0.1, 1 micro M BIO. Cells cultured without BIO treatment were used as controls. During culture expantion, the average doubling time, as an index of the rate of cell growth, were determined and compared. To examine whether or not BIO is able to protect MSCs against apoptosis, the passaged-3 cells from each group were induced to undergo apoptosis with the addition of TNF-alpha [Tumor necrotic factor-alpha]. Three days after, the cultures were quantified in terms of the percentages of apoptotic cells using either the Tunnel or Annexin V staining method. Marrow cells cultivated with 0.1 and 1 micro M BIO appeared to expand at a significantly more rapid rate than the 0.01 micro M BIO and the control cultures [p < 0.05]. Tunnel staining indicated that in 1 micro M BIO-treated groups, there were lower percentages of apoptotic nuclei than in groups with other concentrations of BIO [p < 0.05]. The BIO protective effect appeared to be dose-dependent in that the cultures with high BIO content possessed less apoptotic nuclei. The results obtained by Annexin staining were in agreement with the results of Tunnel staining. The Annexin method additionally takes into account the early apoptotic cells which are not detectable by the Tunnel method. Taken together, it seems that cultivation with BIO could both increase the growth rate of marrow cells and protect MSCs against induced apoptosis

The effect of focal-adhesion micromanipulation in trauma and wound healing / 中华整形外科杂志

<p><b>OBJECTIVE</b>To explore the effect of focal-adhesion micromanipulation on the biological behavior of fibroblast.</p><p><b>METHODS</b>Micro-pot was made by microcontact printing. The molecules of constitutive protein was adhered on micro-pot by self-assemble of peptides. Skin fibroblasts were cultured on the membrane by self-made biomechanical cell culture for 2 weeks. Morphology observation and cell immunohistochemistry analysis was performed.</p><p><b>RESULTS</b>After 2 weeks, the morphology of the fibroblasts was diverse and more compliant. Cell immunohistochemistry analysis found that the expression of integrinbeta1, alpha5 and tensin was dramatically reduced.</p><p><b>CONCLUSIONS</b>The morphology and the biological behaviour of the fibroblasts in hypertrophic scar can be changed after micromanipulation of focal adhesion.</p>

alpha-Tocopheryl succinate potentiates the paclitaxel-induced apoptosis through enforced caspase 8 activation in human H460 lung cancer cells

Paclitaxel is one of the chemotheraputic drugs widely used for the treatment of nonsmall cell lung cancer (NSCLC) patients. Here, we tested the ability of alpha-tocopheryl succinate (TOS), another promising anticancer agent, to enhance the paclitaxel response in NSCLC cells. We found that sub-apoptotic doses of TOS greatly enhanced paclitaxel-induced growth suppression and apoptosis in the human H460 NSCLC cell lines. Our data revealed that this was accounted for primarily by an augmented cleavage of poly(ADP-ribose) polymerase (PARP) and enhanced activation of caspase-8. Pretreatment with z-VAD-FMK (a pan-caspase inhibitor) or z-IETD-FMK (a caspase-8 inhibitor) blocked TOS/paclitaxel cotreatment-induced PARP cleavage and apoptosis, suggesting that TOS potentiates the paclitaxel-induced apoptosis through enforced caspase 8 activation in H460 cells. Furthermore, the growth suppression effect of TOS/paclitaxel combination on human H460, A549 and H358 NSCLC cell lines were synergistic. Our observations indicate that combination of paclitaxel and TOS may offer a novel therapeutic strategy for improving paclitaxel drug efficacy in NSCLC patient therapy as well as for potentially lowering the toxic side effects of paclitaxel through reduced drug dosage.

Bioinsecticide production by the bacterium bacillus thuringiensis [patttern of cell growth, toxin production and by-product synthesis]

To develop a cost-effective process for the production of Bacillus thuringiensis based insecticide, it is important to cultivate the bacterial strain in rich medium to obtain the highest yields of spore-crystal complexes. It was found that cultivation of the bacterium in medium with high concentrations of glucose [50-90 g. l[-1]] resulted in much lower bacterial spores, crystal protein and their toxicity, when tested against Spodoptera littoralis and Anagasta kuehniella larvae. The best results was obtained with glucose concentration of 20.0 g.1[-1] as 7.1 x 10[11] spores/ml[-1] and 3.4 g/l of crystal protein were achieved with LC[50] of 40.1 and 50.2 mg/Kg mail against S. littoralis and A. kuehniella respectively. However, > 21% of the consumed glucose were diverted into by-product synthesis at the expense of spore-crystal protein mixture. Only 78.3% of consumed glucose was converted into spores and crystal protein. Among by-products formed, acetic acid and beta-hydroxybutyric acid [PHB] that were produced during the phase of active growth and glutamic acid and succinic acid during the phase of active toxin production

Comparison of the attachment and growth characteristics between human junctional epithelium and oral epithelium cells / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To compare the attachment and growth characteristics between human junctional epithelium (JE) and oral epithelium cells.</p><p><b>METHODS</b>The healthy JE biopsies were derived from the human teeth extracted due to impaction or orthodontic purpose. Enzyme digestion was used to isolate JE cells, which were then cultured in DKGM. The co-culture model of JE cell-tooth slice was built up by adding 3 decalcification cementum slices (5 mm x 3 mm x 1 mm) into sterilized plate containing 1 ml of JE cells (5 x 10(8)/L), 21 slices all together,and incubated in an atmosphere containing 5% CO2 at 37 degrees C for 1-14 days. The attachment structure was observed under transmission electron microscope, and the OE cells was used as control.</p><p><b>RESULTS</b>The human JE cells were polymorphous in shape and CK19 positive, while OE cells were consisted of equal and closely packed epithelial-like cells in a paving stone arrangement, and CK19 was only strained in a few cells. There were a few cells in JE-slice when co-cultured for 1-3 days, and electron dense plaques on the JE cell surface of the attached slice were observed at 9 days, and 2-3 layer of JE cells and hemidesmosome-like structure formed within 11-14 days. There were more OE cells within 1-3 days, electron dense plaques appeared at 7 days, and stratified epithelium and hemidesmosome-like structure formed in OE-slice at 9 days.</p><p><b>CONCLUSIONS</b>The cultured JE cells were immature and lower differentiated epithelial cells which were different from OE cells. Under the same condition the growth and attachment of JE cells on the cementum slice surface were slower than that of OE cells. Their attachment strength needs further study.</p>

Role of chelates in treatment of cancer.

Chelates are used in cancer as cytotoxic agent, as radioactive agent in imaging studies and in radioimmunotherapy. Various chelates based on ruthenium, copper, zinc organocobalt, gold, platinum, palladium, cobalt, nickel and iron are reported as cytotoxic agent. Monoclonal antibodies labeled with radioactive metals such as yttrium-90, indium-111 and iodine-131 are used in radioimmunotherapy. This review is an attempt to compile the use of chelates as cytotoxic drugs and in radioimmunotherapy.

Sertoli cell proliferation during the post hatching period in domestic fowl

There has been no study aimed at directly determiningof the periods of Sertoli cell proliferation in birds evendomestic fowl. The aims of this study were to observe thecessation of post-hatching mitotic proliferation of Sertolicells in domestic fowl, and to determine the volumedensity of Sertoli and germ cells during this period. Atotal of 50 Leghorn chicks were used in this study. Thetestes sections of the animals were immunostained withBrdU to observe the proliferation of cells from one to 10weeks of age. The volume density of the Sertoli and germcells were determined using the standard point countingmethod. The volume density of the germ cell nuclei wasinitially less than that of the Sertoli cells but the volumedensity converged by week 6, and remained relativelyconstant until the commencement of meiosis. Clearlabeling of Sertoli and germ cells was observed from week1 to week 7. The only those cells still labeled after 8 weekswere germ cells, indicating that Sertoli cell proliferationhad ceased. Therefore, it is recommended that anyresearch into the testes of domestic fowl should considerthe cessation of Sertoli cell proliferation by approximately8 weeks.

Effect of Nocardia rubra cell wall skeleton on the growth of HeLa cell line infected with HPV / 中华实验和临床病毒学杂志

<p><b>OBJECTIVE</b>To investigate the effects of Nocardia rubra cell wall skeleton (Nr-CWS) on the HeLa cell line, one of the cell lines of human cervical cancer, infected with HPV.</p><p><b>METHODS</b>HPV-infected HeLa (HPV 18-positive cells) cultured in vitro were divided into two groups: the experiment group and control group. Nr-CWS was added to the experiment group and PBS to the control. The growth and proliferation of HeLa cells were detected with MTT and flow cytometry technology. Inhibitive effect of HeLa transplanted tumor was investigated in Scid mice.</p><p><b>RESULTS</b>The growth of HeLa cells in the experimental group was apparently decreased compared with that of the control. The results of flow cytometry demonstrated that more HeLa cells were transferred into quiescent phase in the experimental group than that in the control. While less in the proliferative phase, both of the volume and weight of HeLa transplanted tumor with drug-added group were less than those of control group.</p><p><b>CONCLUSION</b>The Nocardia rubra cell wall skeleton is a potiental growth inhibitor and inducer of apoptosis of cervical cancer cells in vitro and may provide a new way in prevention or supplementary management of anti-human papilloma virus.</p>

Biological characteristics of Chinese hamster ovary cells transfected with bovine Prnp

A normal prion protein (PrPc) is converted to a proteaseresistant isoform by an apparent self-propagating activity in transmissible spongiform encephalopathy, a neurodegenerative disease. The cDNA encoding open reading frame (ORF) of the bovine prion protein gene (Prnp) was cloned from Korean cattle by PCR, and was transfected into Chinese hamster ovary (CHO-K1) cells using lipofectamine. The gene expression of the cloned cDNA was confirmed by RT-PCR and Western blotting with the monoclonal antibody, 6H4. Cellular changes in the transfected CHO-K1 cells were investigated using parameters such as MTT, lactate dehydrogenase (LDH), and superoxide dismutase (SOD) activities, as well as nitric oxide (NO) production, and an apoptosis assay. In the MTT and LDH assays, the bovine PrnP-transfectant showed a lower proliferation rate than the wild-type (p < 0.05). Production of NO, after LPS or ConA stimulation, was not detected in either transfectants or CHO-K1 cells. In SOD assay under ConA stimulation, the SOD activity of transfectants was 10 times higher than that of CHO-K1 cells at 6 h after treatment (p < 0.05). The genomic DNA of both the transfectants and control cells began to be fragmented at 6 h after treatment with cyclohexamide. Caspase-3 activity was reduced by transfection with the bovine Prnp (p < 0.05). Conclusively, the viability of transfectants expressing exogenous bovine Prnp was decreased while the capacities for cellular protection against antioxidative stress and apoptosis were increased.

Effect of proline rich domain of an RNA-binding protein Sam68 in cell growth process, death and B cell signal transduction / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Sam68 plays an important role as a multiple functional RNA binding nuclear protein in cell cycle progress, RNA usage, signal transduction, and tyrosine phosphorylation by Src during mitosis. However, its precise impact on these essential cellular functions remains unclear. The purpose of this study is to further elucidate Sam68 functions in RNA metabolism, signal transduction regulation of cell growth and cell proliferation in DT40 cell line.</p><p><b>METHODS</b>By using gene targeting method, we isolated a mutation form of Sam68 in DT40 cells and described its effect on cell growth process and signal transduction. Southern, Northern, and Western blot, phosphorylation and flow-cytometric analyses were performed to investigate the Sam68 functions.</p><p><b>RESULTS</b>A slower growth rate (2.1 hours growth elongation) and longer S phase (1.7 hours elongation) was observed in the Sam68 mutant cells. Serum depletion resulted in increased amounts of dead cells, and expansion of S phase in mutant cells. Upon B cell cross-linking, the maximal level of tyrosine phosphorylation on BLNK was observed to be significantly lower in mutant cells.</p><p><b>CONCLUSIONS</b>The proline rich domain of Sam68 is involved in cell growth control by modulating the function of mRNAs in S phase or earlier and the functions as an adaptor molecule in B cell signal transduction pathways.</p>