Biogenesis of MiRNA-195 and its role in biogenesis, the cell cycle, and apoptosis

microRNA-195(miR-195) is an important member of the micro-15/16/195/424/497 family, and which is activated in multiple diseases, such as cancers, heart failure, and schizophrenia. Mir-195 regulates a plethora of target proteins, which are involved in the cell cycle, apoptosis, proliferation. WEE1, CDK6, and Bcl-2 are confirmed target genes of miR-195 that are involved in miR-195-mediated cell-cycle and apoptosis effects. However, the mechanism of miR-195 action is not completely understood. This review summarizes recent the research progress regarding the roles of miR-195 in the cell cycle and in apoptosis.     

Cell division cycle 20 promotes cell proliferation and invasion and inhibits apoptosis in osteosarcoma cells

Cdc20 (cell division cycle 20 homologue) has been reported to exhibit an oncogenic role in human tumorigenesis. However, the function of Cdc20 in osteosarcoma (OS) has not been investigated. In the current study, we aim to explore the role of Cdc20 in human OS cells. Multiple approaches were used to measure cell growth, apoptosis, cell cycle, migration and invasion in OS cells after depletion of Cdc20 or overexpression of Cdc20. We found that down-regulation of Cdc20 inhibited cell growth, induced apoptosis and triggered cell cycle arrest in OS cells. Moreover, Cdc20 down-regulation let to inhibition of cell migration and invasion in OS cells. Consistently, overexpression of Cdc20 in OS cells promoted cell growth, inhibited apoptosis, enhanced cell migration and invasion. Mechanistically, our Western blotting results showed that overexpression of Cdc20 reduced the expression of Bim and p21, whereas depletion of Cdc20 upregulated Bim and p21 levels in OS cells. Altogether, our findings demonstrated that Cdc20 exerts its oncogenic role partly due to regulation of Bim and p21 in OS cells, suggesting that targeting Cdc20 could be useful for the treatment of OS.     

Effect of regulated expression of the fragile histidine traid gene on cell cycle and proliferation

The mechanism of tumor suppressor action of the fragile histidine triad (FHIT) gene is unknown. Disruption of cell cycle regulation leads to the tumor formation and many tumor suppressor genes suppress tumorigenesis through their effect on cell cycle regulation. We examined the expression of FHIT during the cell cycle, and determined whether overexpression of FHIT affects cell cycle kinetics and apoptosis. The FHIT cDNA was cloned into the ecdysone-inducible expression vector in both the sense and antisense orientations. Overexpression of the sense or antisense construct did not affect cell proliferation, cell cycle distribution or apoptosis in human 293T cells. Analysis of the FHIT expression in 293T cells collected at various cell cycle phases showed that the expression of FHIT is not under cell cycle regulation. These results indicate that the tumor suppressor activity of the FHIT gene may be independent of an effect on the cell cycle and apoptosis mechanisms.     

Effect of sodium butyrate on the hepatoma cell cycle: Possible use for cell synchronization

Summary Exposure of HTC cells to sodium butyrate caused inhibition of growth. The site of growth inhibition was studied by time-lapse cinematography and [³H]thymidine incorporation studies. Evidence is presented that sodiunm butyrate affected the cell cycle at a specific point immediately after mitosis. Inasmuch as it does not modify the interphase duration after its removal, butyrate may be used for HTC synchronization. This work was supported by l'Institut Nationale de la Santé et de la Recherche Médicale and la Centre Nationale de la Recherche Scientifique (L. T. and J. K.).     

Biochemical and morphological identification of ceramide-induced cell cycle arrest and apoptosis in cultured granulosa cells

We have investigated the effects of ceramide on the progression of cell cycle and on apoptotic cell death in ovarian cultured granulosa cells. Rates of cellular proliferation were measured by immunocytochemical staining for proliferating cell nuclear antigen (PCNA) and flow cytometric cell cycle analysis. We also examined for morphological and biochemical signs of apoptosis. The PCNA expression was downregulated in a dose-dependent manner after treatment with C6-ceramide. Flow cytometric analysis demonstrated that the exposure of granulosa cells to C6-ceramide markedly decreased the population associated with G0/G1 DNA content and the reduction of cell numbers in G0/G1 phase was accompanied by the elevation of the A0 phase. The exposure of granulosa cells to exogenous C6-ceramide induced drastic morphological changes including cytoplasmic- or nuclear condensation and typical apoptotic DNA degradation. We also observed that phorbol 12-myristate 13-acetate, a protein kinase C (PKC) activator, significantly inhibited the ceramide-induced apoptosis. These results suggested that ceramide might block the progression of cell cycle at G0/G1 phase and as a consequence, granulosa cells would be committed to apoptosis. Our findings also indicated that down-regulation of the PKC activity might be involved in the ceramide-induced apoptosis in cultured granulosa cells.     

乳酸杆菌发酵滤液对人宫颈癌细胞株Hela细胞的细胞周期和细胞凋亡的影响

目的观察乳酸杆菌DM9811发酵滤液对宫颈癌细胞株Hela细胞的细胞周期和细胞凋亡的影响,探索乳酸杆菌发酵滤液对宫颈癌细胞作用的可能机制。方法用光镜、电镜和流式细胞仪分析不同浓度乳酸杆菌DM9811发酵滤液对Hela细胞凋亡的诱导效果;用流式细胞仪分析不同浓度乳酸杆菌DM9811发酵滤液对Hela细胞细胞周期的影响。结果（1）乳酸杆菌DM9811发酵滤液可诱导宫颈癌Hela细胞凋亡。形态学观察处理后的Hela细胞,可见细胞变形,细胞皱缩,体积变小,细胞间隙增大,细胞核固缩。流式细胞仪分析,1%、2%的乳酸杆菌DM9811发酵滤液在48、72h可诱导Hela细胞凋亡;5%的乳酸杆菌发酵滤液在24、48和72h均可诱导Hela细胞凋亡。（2）乳酸杆菌DM9811发酵滤液阻滞宫颈癌Hela细胞于S期,不同浓度的乳酸杆菌发酵滤液作用24、48和72h均可使S期细胞比阴性对照组增多。结论乳酸杆菌DM9811发酵滤液可诱导部分Hela细胞凋亡,其对Hela细胞的生长抑制作用可能通过S期阻滞实现。     

The effect of chelerythrine on cell growth, apoptosis, and cell cycle in human normal and cancer cells in comparison with sanguinarine

We compared the effects of chelerythrine (CHE) and sanguinarine (SA) on human prostate cancer cell lines (LNCaP and DU-145) and primary culture of human gingival fibroblasts. CHE and SA treatment of cell lines for 24 h resulted in (1) inhibition of cell viability in a dose-dependent manner in all tested cells (as evaluated by MTT test and bromodeoxyuridine incorporation assay); (2) dose-dependent increase in DNA damage in all tested cells (as evaluated by DNA comet assay); (3) changes in apoptosis (assessed by western blot analysis and TUNEL assay); and (4) significant induction of cyclin kinase inhibitors p21^Waf1/Cip1 and p27^Kip1 in prostate cancer cells (identified by western blot analysis). Our study demonstrates that CHE had significant cytotoxic effect, independent of p53 and androgen status, on human prostate cancer cell lines. Normal gingival fibroblasts and DU-145 cells were more sensitive to the treatment with both alkaloids than were LNCaP cells. CHE and SA may be prospective natural molecules for use in the treatment of prostate cancer owing to their involvement in apoptosis and cell cycle regulation.     

Functional roles of PC‐PLC and Cdc20 in the cell cycle,proliferation, and apoptosis

Phosphatidylcholine‐specific phospholipase C (PC‐PLC) is the major enzyme in the Phosphatidylcholine (PC) cycle and is involved in many long‐term cellular responses such as activation, proliferation, and differentiation events. Cell division cycle 20 homolog (Cdc20) is an essential cell‐cycle regulator required for the completion of mitosis. Our previous studies identified the interaction between PC‐PLC and Cdc20. Through the interaction, Cdc20 could mediate the degradation of PC‐PLC by Cdc20‐mediated ubiquitin proteasome pathway (UPP). In this study, we found that PC‐PLC might not be involved in cancer metastasis. Inhibition of PC‐PLC by D609 could cause cell proliferation inhibition and apoptosis inhibition in CBRH‐7919 cells. Inhibition of PC‐PLC could also influence the cell cycle by arresting the cells in G1 phase, and Cdc20 might be involved in these processes. Taken together, in this report, we provided new evidence for the functional roles of PC‐PLC and Cdc20 in the cell cycle, proliferation, and apoptosis in CBRH‐7919 cells. Copyright © 2010 John Wiley & Sons, Ltd.     

Downregulation of EIF5A2 by miR-221-3p inhibits cell proliferation,promotes cell cycle arrest and apoptosis in medulloblastoma cells

Recently, miR-221-3p expression has been reported to be down-regulated in medulloblastoma (MB), but its functional effects remains unclear. In this study, quantitative real-time PCR (qRT-PCR) revealed significantly decreased miR-221-3p in MB cell lines. Transfection of miR-221-3p mimics reduced, or inhibitor increased cell proliferation in MB cells using MTT assay. Flow cytometry analysis indicated miR-221-3p overexpression promoted, while knockdown alleviated G0/G1 arrest and apoptosis. Luciferase reporter assay confirmed miR-221-3p directly targets the EIF5A2 gene. Moreover, restoration of EIF5A2 in the miR-221-3p-overexpressing DAOY cells significantly alleviated the suppressive effects of miR-221-3p on cell proliferation, cell cycle and apoptosis. Furthermore, miR-221-3p overexpression decreased CDK4, Cyclin D1 and Bcl-2 and increased Bad expression, which was reversed by EIF5A2 overexpression. These results uncovered the tumor suppressive role of miR-221-3p in MB cell proliferation at least in part via targeting EIF5A2, suggesting that miR-221-3p might be a potential candidate target for diagnosis and therapeutics of MB.     

Effect of retinoic acid on the proliferation and tumorigenicity of mouse mastocytoma cells

Retinoic acid (RA) inhibited the in vitro growth of the mouse mast cell tumor line P₈₁₅ in a dose- and time-dependent manner. The inhibition was accompanied by an increase in the amount of neutral intracellular mucopolysaccharides. Study of cell cycle kinetics showed that exposure to retinoic acid led to a slowing-down of the cell-cycle progression possibly related to a more differentiated cell population disclosed by microscopy with a lower proliferative capacity. In vivo, delays in both tumor appearance and mouse mortality were observed after injecting RA into mice bearing mastocytomas. These results suggest that RA could be of interest in the treatment of human malignant systemic mastocytosis with proliferation of immature mast cells.     

Potassium channels in cell cycle and cell proliferation

Normal cell-cycle progression is a crucial task for every multicellular organism, as it determines body size and shape, tissue renewal and senescence, and is also crucial for reproduction. On the other hand, dysregulation of the cell-cycle progression leading to uncontrolled cell proliferation is the hallmark of cancer. Therefore, it is not surprising that it is a tightly regulated process, with multifaceted and very complex control mechanisms. It is now well established that one of those mechanisms relies on ion channels, and in many cases specifically on potassium channels. Here, we summarize the possible mechanisms underlying the importance of potassium channels in cell-cycle control and briefly review some of the identified channels that illustrate the multiple ways in which this group of proteins can influence cell proliferation and modulate cell-cycle progression.     

Advances in biotechnological production of butyric acid

The review is focused on several aspects of butyric acid production: butyric acid-producing bacterial strains, the characteristics of the genus Clostridium (the bacterium most used for butyrate production), and alternative methods of obtaining butyric acid by alcohol biotransformation. Further, the main metabolic pathways of butyrate production, and possibilities for their control are outlined. Batch, fed-batch or continuous fermentation combined with cell recycle or immobilization are applicable for anaerobic fermentations using Clostridium as the production strain. The best process comprises a combination of high cell concentration and slowly growing biomass, in addition to high production selectivity and low inhibitory effects of the end-product. Inhibitory effects may be avoided by on-line removal of the end-product. Extraction alone or extraction combined with simultaneous stripping of the organic phase (liquid membrane) into the second aqueous phase (pertraction) seem to be the most suitable methods for on-line butyrate removal. The biocompatibility and the distribution coefficient of the organic phase under fermentation conditions should be considered before designing a fermentation apparatus. Journal of Industrial Microbiology & Biotechnology (2000) 24, 153–160. Received 12 August 1999/ Accepted in revised form 03 December 1999     

Epigallocatechin gallate protects U937 cells against nitric oxide-induced cell cycle arrest and apoptosis

Ingesting phenolic phytochemicals in many plant products may promote health, but the effects of phenolic phytochemicals at the cellular level have not been fully examined. Thus, it was determined if the tea phenolic phytochemical, epigallocatechin gallate (EGCG), protects U937 human pro-monocytic cells against the nitrogen free radical, nitric oxide (*NO). Cells were incubated for 4-6 h with 500 microM S-nitrosoglutathione (GSNO), which generates *NO, but this did not induce single-strand breaks in DNA. Nevertheless, 82 +/- 4% of GSNO-treated cells, compared to only 39 +/- 1% of untreated cells, were arrested in the G(1)-phase of the cell cycle. However, dosing the GSNO-treated cells with 9, 14, or 18 microg/ml of EGCG resulted in only 74 +/- 8%, 66 +/- 1%, and 43 +/- 3% of the cells, respectively, in the G(1)-phase. Exposing cells to GSNO also resulted in the emergence of a sub-G(1) apoptotic cell population numbering 14 +/- 3%, but only 5 +/- 2%, 5 +/- 1%, and 2 +/- 0% upon dosing of the GSNO-treated cells with 9, 14, and 18 microg/ml of EGCG, respectively. Furthermore, exposing cells to GSNO resulted in greater cell surface binding of annexin V-FITC, but binding was 41-89% lower in GSNO-treated cells dosed with EGCG. Collectively, these data suggest that *NO or downstream products induced cell cycle arrest and apoptosis that was not due to single-strand breaks in DNA, and that EGCG scavenged cytotoxic *NO or downstream products, thus reducing the number of cells in a state of cell cycle arrest or apoptosis.     

Differential regulation of survivin by p53 contributes to cell cycle dependent apoptosis

Recent studies indicate that cell-cycle checkpoints are tightly correlated with the regulation of apoptosis, in which p53 plays an important role. Our present works show that the expression of E6/E7 oncogenes of human papillomavirus in HeLa cells is inhibited in the presence of anti-tumor reagent tripchlorolide (TC), which results in the up-regulation of p53 in HeLa cells. Interestingly, under the same TC-treatment, the cells at the early S-phase are more susceptible to apoptosis than those at the middle S-phase although p53 protein is stabilized to the same level in both situations. Significant difference is exhibited between the two specified expression profiles. Further analysis demonstrates that anti-apoptotic gene survivin is up-regulated by p53 in the TC-treated middle-S cells, whereas it is down-regulated by p53 in the TC-treated early-S cells. Taken together, the present study indicates that the differential p53-regulated expression of survivin at different stages of the cell cycle results in different cellular outputs under the same apoptosis-inducer.     

Reversine suppresses oral squamous cell carcinoma via cell cycle arrest and concomitantly apoptosis and autophagy

Background

The effective therapies for oral cancer patients of stage III and IV are generally surgical excision and radiation combined with adjuvant chemotherapy using 5-Fu and Cisplatin. However, the five-year survival rate is still less than 30% in Taiwan. Therefore, evaluation of effective drugs for oral cancer treatment is an important issue. Many studies indicated that aurora kinases (A, B and C) were potential targets for cancer therapies. Reversine was proved to be a novel aurora kinases inhibitor with lower toxicity recently. In this study, the potentiality for reversine as an anticancer agent in oral squamous cell carcinoma (OSCC) was evaluated.

Methods

Effects of reversine on cell growth, cell cycle progress, apoptosis, and autophagy were evaluated mainly by cell counting, flow cytometry, immunoblot, and immunofluorescence.

Results

The results demonstrated that reversine significantly suppressed the proliferation of two OSCC cell lines (OC2 and OCSL) and markedly rendered cell cycle arrest at G2/M stage. Reversine also induced cell death via both caspase-dependent and -independent apoptosis. In addition, reversine could inhibit Akt/mTORC1 signaling pathway, accounting for its ability to induce autophagy.

Conclusions

Taken together, reversine suppresses growth of OSCC via multiple mechanisms, which may be a unique advantage for developing novel therapeutic regimens for treatment of oral cancer in the future.