Chloroform Fraction of Methanolic Extract of Seeds of Annona muricata Induce S Phase Arrest and ROS Dependent Caspase Activated Mitochondria Mediated Apoptosis in Triple Negative Breast Cancer

2020 ◽  
Vol 20 ◽  
Author(s):  
Ajith J. George ◽  
Bibu J. Kariyil ◽  
Usha P.T. Ayyappan ◽  
Anu Gopalakrishnan
Keyword(s):  
Cell Cycle ◽  
Cell Lines ◽  
Triple Negative ◽  
S Phase ◽  
Chloroform Fraction ◽  
Annona Muricata ◽  
In Vivo Evaluation ◽  
Annonaceous Acetogenins

Background: Triple negative breast cancers (TNBCs) are having high morbidity and shorter survival rate in the population. These types of cancers are having high aggressiveness, lymphatic invasion and absence of receptors. The treatment options for these types of cancers are also scarce. Several studies have been conducted to investigate the effectiveness of seeds of Annona muricata for its anti cancer activities in various cancer cell lines such as lung A549, breast MCF7, colon HT-29, oral KB and human hepatoma cell lines. But works related to its anticancer effect and mechanism of action in TNBCs has not been elucidated. Objective: The present study was undertaken to evaluate the in vitro, in vivo and in silico anticancer potential of chloroform fraction of methanolic extract of seeds of Annona muricata (CMAM) against TNBC along with elucidation of its mechanistic pathway. Methods: In vitro cytotoxicity- and antiproliferative- studies in three triple negative breast cancer cell lines were conducted using MTT and SRB assays respectively. The mechanism through which CMAM exerts its pharmacological effect was elucidated in vitro employing cell morphological assessment studies using acridine orange/ ethidium bromide (AO/EB), intra cellular reactive oxygen species assay, DNA fragmentation assay, agarose gel electrophoresis, terminal deoxynucleotidyl transferase dUTP nick end labelling (TUNEL) assay, cell cycle analysis, annexin binding assay and caspase activated mitochondria mediated apoptotic assays using western blot. In vivo evaluation in 4T1 induced murine mammary tumour model was also conducted. Phytoconstituents in CMAM was analysed using liquid chromatography mass spectroscopy. In silico binding studies with various annonaceous acetogenins against BCL-2 and cyclin E were performed. Results: Cytotoxicity studies in MDA-MD-231, 4TI and BT-549 revealed the IC50 value of CMAM to be 2.5±0.14, 4.8±0.3 and 4.5±0.16 µg/mL respectively. Anti proliferative studies in 4T1, MDA-MB-231 and BT-549 revealed the GI50 values to be 0.128+0.03, 18.03+0.20, 0.95+0.04 µg/mL respectively. CMAM exhibited its cytotoxicity through the lysis of cell membrane, ROS dependent caspase activated mitochondria mediated apoptosis, and arresting the S phase of the cell cycle. In vivo evaluation also supported the tumoricidal property of CMAM as evidenced by reduction in tumour volume and serum biomarkers. Histopathologically there was a marked reduction in cellularity, nuclear chromatin condensation and a few normal cells in group treated with CMAM at a dose of 31mg/Kg. Phytoconstituent evaluation has revealed the presence of annonaceous acetogenins in CMAM. Among the various annonaceous acetogenins, muricatacin alone showed lipophilicity and binding affinity towards BCL-2 and cyclin E1. Conclusion: The current study shows the effectiveness of CMAM against TNBC both in vitro and in vivo. This anticancerous effect of CMAM could be by virtue of its ROS dependent caspase activated mitochondria mediated apoptosis and the S-phase arrest of the cell cycle in the TNBCs. Our results indicate that the presence of annonaceous acetogenins, especially muricatacin, could be contributing to this anticanceros effect of CMAM. Thus muricatacin could be a potential candidate for the targeted therapy of TNBCs.

scholarly journals Mibefradil inhibits the proliferation of triple-negative breast cancer by targeting AURKA to regulate apoptosis signal pathway

2021 ◽  
Author(s):  
Xu Han ◽  
Xiujuan Qu ◽  
Beixing Liu ◽  
Yizhe Wang ◽  
Yang Cheng ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Cell Cycle ◽  
Molecular Docking ◽  
Triple Negative Breast Cancer ◽  
Triple Negative ◽  
Therapeutic Drug ◽  
Specific Gene ◽  
In Vivo Models

Abstract Background: Triple negative breast cancer (TNBC) is a tumor characterized by high recurrence and mortality, but without effective targeted therapy. It is urgent to explore new treatment strategy to improve the efficacy of TNBC therapy. Methods: Transcriptomic profiling datasets of TNBC were used for screening TNBC specific gene sets. Drug prediction was performed in Connectivity map (CMap) database. Molecular docking method was used for analyzing drug targets. In vitro and in vivo models of TNBC were constructed to examine the drug efficacy. Results: We screened out Mibefradil, a T-type Ca2+ channel blocker, might be a potential therapeutic drug for TNBC by transcriptomics and bioinformatics analysis, and verified that Mibefradil could inhibit the proliferation of TNBC cells by inducing apoptosis and cell cycle arrest. Furthermore, by network pharmacology and molecular docking analysis, AURKA was predicted as the most possible drug target of Mibefradil. Finally, it was proved that Mibefradil treatment could induce apoptosis by decreasing protein expression and phosphorylation level of AURKA in vitro and in vivo. Conclusions: Mibefradil played anti-cancer role in TNBC cells by targeting to AURKA to induce cell cycle and apoptosis. Our results repurposed Mibefradil as a potential targeted drug of TNBC and provided a fundamental research for a novel strategy TNBC treatment.

scholarly journals Differences in cell cycle characteristics among patients with acute nonlymphocytic leukemia

Blood ◽  
1987 ◽  
Vol 69 (6) ◽  
pp. 1647-1653 ◽  
Author(s):  
A Raza ◽  
Y Maheshwari ◽  
HD Preisler
Keyword(s):  
Cell Cycle ◽  
Tritiated Thymidine ◽  
S Phase ◽  
Total Cell ◽  
Acute Nonlymphocytic Leukemia ◽  
Cell Cycle Time ◽  
Myeloid Leukemias ◽  
History Of

The proliferative characteristics of myeloid leukemias were defined in vivo after intravenous infusions of bromodeoxyuridine (BrdU) in 40 patients. The percentage of S-phase cells obtained from the biopsies (mean, 20%) were significantly higher (P = .00003) than those determined from the bone marrow (BM) aspirates (mean, 9%). The post- BrdU infusion BM aspirates from 40 patients were incubated with tritiated thymidine in vitro. These double-labeled slides were utilized to determine the duration of S-phase (Ts) in myeloblasts and their total cell cycle time (Tc). The Ts varied from four to 49 hours (mean, 19 hours; median, 17 hours). Similarly, there were wide variations in Tc of individual patients ranging from 16 to 292 hours (mean, 93 hours; median, 76 hours). There was no relationship between Tc and the percentage of S-phase cells, but there was a good correlation between Tc and Ts (r = .8). Patients with relapsed acute nonlymphocytic leukemia (ANLL) appeared to have a longer Ts and Tc than those studied at initial diagnosis. A subgroup of patients at either extreme of Tc were identified who demonstrated clinically documented resistance in response to multiple courses of chemotherapy. We conclude that Ts and Tc provide additional biologic information that may be valuable in understanding the variations observed in the natural history of ANLL.

scholarly journals Tanshinone IIA Inhibits Osteosarcoma Growth through a Src Kinase-Dependent Mechanism

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Chao Hu ◽  
Xiaobin Zhu ◽  
Taogen Zhang ◽  
Zhouming Deng ◽  
Yuanlong Xie ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Proliferation ◽  
Signaling Pathways ◽  
Cell Lines ◽  
Src Kinase ◽  
Akt Signaling ◽  
Cellular Level ◽  
Tanshinone Iia

Introduction. Osteosarcoma is a malignant tumor associated with high mortality rates due to the toxic side effects of current therapeutic methods. Tanshinone IIA can inhibit cell proliferation and promote apoptosis in vitro, but the exact mechanism is still unknown. The aims of this study are to explore the antiosteosarcoma effect of tanshinone IIA via Src kinase and demonstrate the mechanism of this effect. Materials and Methods. Osteosarcoma MG-63 and U2-OS cell lines were stable transfections with Src-shRNA. Then, the antiosteosarcoma effect of tanshinone IIA was tested in vitro. The protein expression levels of Src, p-Src, p-ERK1/2, and p-AKt were detected by Western blot and RT-PCR. CCK-8 assay and BrdU immunofluorescence assay were used to detect cell proliferation. Transwell assay, cell scratch assay, and flow cytometry were used to detect cell invasion, migration, and cell cycle. Tumor-bearing nude mice with osteosarcoma were constructed. The effect of tanshinone IIA was detected by tumor HE staining, tumor inhibition rate, incidence of lung metastasis, and X-ray. Results. The oncogene role of Src kinase in osteosarcoma is reflected in promoting cell proliferation, invasion, and migration and in inhibiting apoptosis. However, Src has different effects on cell proliferation, apoptosis, and cell cycle regulation among cell lines. At a cellular level, the antiosteosarcoma effect of tanshinone IIA is mediated by Src downstream of the MAPK/ERK and PI3K/AKt signaling pathways. At the animal level, tanshinone IIA played a role in resisting osteosarcoma formation by Src downstream of the MAPK/ERK and PI3K/AKt signaling pathways. Conclusion. Tanshinone IIA plays an antiosteosarcoma role in vitro and in vivo and inhibits the progression of osteosarcoma mediated by Src downstream of the MAPK/ERK and PI3K/AKt signaling pathways.

scholarly journals Menadione reduces CDC25B expression and promotes tumor shrinkage in gastric cancer

2020 ◽  
Vol 13 ◽  
pp. 175628481989543
Author(s):  
Amanda Braga Bona ◽  
Danielle Queiroz Calcagno ◽  
Helem Ferreira Ribeiro ◽  
José Augusto Pereira Carneiro Muniz ◽  
Giovanny Rebouças Pinto ◽  
...  
Keyword(s):  
Gastric Cancer ◽  
Cell Cycle ◽  
Cell Cycle Arrest ◽  
Cell Lines ◽  
Specific Inhibitor ◽  
Gastric Carcinogenesis ◽  
In Vivo Experiments ◽  
Cycle Arrest

Background: Gastric cancer is one of the most incident types of cancer worldwide and presents high mortality rates and poor prognosis. MYC oncogene overexpression is a key event in gastric carcinogenesis and it is known that its protein positively regulates CDC25B expression which, in turn, plays an essential role in the cell division cycle progression. Menadione is a synthetic form of vitamin K that acts as a specific inhibitor of the CDC25 family of phosphatases. Methods: To better understand the menadione mechanism of action in gastric cancer, we evaluated its molecular and cellular effects in cell lines and in Sapajus apella, nonhuman primates from the new world which had gastric carcinogenesis induced by N-Methyl-N-nitrosourea. We tested CDC25B expression by western blot and RT-qPCR. In-vitro assays include proliferation, migration, invasion and flow cytometry to analyze cell cycle arrest. In in-vivo experiments, in addition to the expression analyses, we followed the preneoplastic lesions and the tumor progression by ultrasonography, endoscopy, biopsies, histopathology and immunohistochemistry. Results: Our tests demonstrated menadione reducing CDC25B expression in vivo and in vitro. It was able to reduce migration, invasion and proliferation rates, and induce cell cycle arrest in gastric cancer cell lines. Moreover, our in-vivo experiments demonstrated menadione inhibiting tumor development and progression. Conclusions: We suggest this compound may be an important ally of chemotherapeutics in the treatment of gastric cancer. In addition, CDC25B has proven to be an effective target for investigation and development of new therapeutic strategies for this malignancy.

scholarly journals Anticancer Activity of Cynomorium coccineum

Cancers ◽  
2018 ◽  
Vol 10 (10) ◽  
pp. 354 ◽  
Author(s):  
Mouna Sdiri ◽  
Xiangmin Li ◽  
William Du ◽  
Safia El-Bok ◽  
Yi-Zhen Xie ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Death ◽  
Anticancer Activity ◽  
Cancer Cells ◽  
Cell Lines ◽  
Cancer Cell ◽  
Cell Cycle Progression ◽  
Cycle Progression

The extensive applications of Cynomorium species and their rich bioactive secondary metabolites have inspired many pharmacological investigations. Previous research has been conducted to examine the biological activities and numerous interesting pharmaceutical activities have been reported. However, the antitumor activities of these species are unclear. To understand the potential anticancer activity, we screened Cynomorium coccineum and Cynomorium songaricum using three different extracts of each species. In this study, the selected extracts were evaluated for their ability to decrease survival rates of five different cancer cell lines. We compared the cytotoxicity of the three different extracts to the anticancer drug vinblastine and one of the most well-known medicinal mushrooms Amaurederma rude. We found that the water and alcohol extracts of C. coccineum at the very low concentrations possessed very high capacity in decreasing the cancer cells viability with a potential inhibition of tumorigenesis. Based on these primitive data, we subsequently tested the ethanol and the water extracts of C. coccineum, respectively in in vitro and in vivo assays. Cell cycle progression and induction of programmed cell death were investigated at both biological and molecular levels to understand the mechanism of the antitumor inhibitory action of the C. coccineum. The in vitro experiments showed that the treated cancer cells formed fewer and smaller colonies than the untreated cells. Cell cycle progression was inhibited, and the ethanol extract of C. coccineum at a low concentration induced accumulation of cells in the G1 phase. We also found that the C. coccineum’s extracts suppressed viability of two murine cancer cell lines. In the in vivo experiments, we injected mice with murine cancer cell line B16, followed by peritoneal injection of the water extract. The treatment prolonged mouse survival significantly. The tumors grew at a slower rate than the control. Down-regulation of c-myc expression appeared to be associated with these effects. Further investigation showed that treatment with C. coccineum induced the overexpression of the tumor suppressor Foxo3 and other molecules involved in inducing autophagy. These results showed that the C. coccineum extract exerts its antiproliferative activity through the induction of cell death pathway. Thus, the Cynomorium plants appear to be a promising source of new antineoplastic compounds.

scholarly journals Functional Interactions between Herpesvirus Oncoprotein MEQ and Cell Cycle Regulator CDK2

1999 ◽  
Vol 73 (5) ◽  
pp. 4208-4219 ◽  
Author(s):  
Juinn-Lin Liu ◽  
Ying Ye ◽  
Zheng Qian ◽  
Yongyi Qian ◽  
Dennis J. Templeton ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Phosphorylation Site ◽  
Fibroblast Cell ◽  
S Phase ◽  
Morphological Transformation ◽  
Necrosis Factor Alpha ◽  
Coiled Bodies ◽  
Cdk Phosphorylation

ABSTRACT Marek’s disease virus, an avian alphaherpesvirus, has been used as an excellent model to study herpesvirus oncogenesis. One of its potential oncogenes, MEQ, has been demonstrated to transform a rodent fibroblast cell line, Rat-2, in vitro by inducing morphological transformation and anchorage- and serum-independent growth and by protecting cells from apoptosis induced by tumor necrosis factor alpha, C2-ceramide, UV irradiation, or serum deprivation. In this report, we show that there is a cell cycle-dependent colocalization of MEQ protein and cyclin-dependent kinase 2 (CDK2) in coiled bodies and the nucleolar periphery during the G1/S boundary and early S phase. To our knowledge, this is the first demonstration that CDK2 is found to localize to coiled bodies. Such an in vivo association and possibly subsequent phosphorylation may result in the cytoplasmic translocation of MEQ protein. Indeed, MEQ is expressed in both the nucleus and the cytoplasm during the G1/S boundary and early S phase. In addition, we were able to show in vitro phosphorylation of MEQ by CDKs. We have mapped the CDK phosphorylation site of MEQ to be serine 42, a residue in the proximity of the bZIP domain. An indirect-immunofluorescence study of the MEQ S42D mutant, in which the CDK phosphorylation site was mutated to a charged residue, reveals more prominent cytoplasmic localization. This lends further support to the notion that the translocation of MEQ is regulated by phosphorylation. Furthermore, phosphorylation of MEQ by CDKs drastically reduces the DNA binding activity of MEQ, which may in part account for the lack of retention of MEQ oncoprotein in the nucleus. Interestingly, the localization of CDK2 in coiled bodies and the nucleolar periphery is observed only in MEQ-transformed Rat-2 cells, implicating MEQ in modifying the subcellular localization of CDK2. Taken together, our data suggest that there is a novel reciprocal modulation between the herpesvirus oncoprotein MEQ and CDK2.

Alterations in the cell cycle of mouse cumulus granulosa cells during expansion and mucification in vivo and in vitro

1996 ◽  
Vol 8 (6) ◽  
pp. 935 ◽  
Author(s):  
AW Schuetz ◽  
DG Whittingham ◽  
R Snowden
Keyword(s):  
Cell Cycle ◽  
Dna Synthesis ◽  
Granulosa Cells ◽  
Dna Content ◽  
Cumulus Cell ◽  
Cumulus Cells ◽  
Ovarian Follicles ◽  
S Phase

The cell cycle characteristics of mouse cumulus granulosa cells were determined before, during and following their expansion and mucification in vivo and in vitro. Cumulus-oocyte complexes (COC) were recovered from ovarian follicles or oviducts of prepubertal mice previously injected with pregnant mare serum gonadotrophin (PMSG) or a mixture of PMSG and human chorionic gonadotrophin (PMSG+hCG) to synchronize follicle differentiation and ovulation. Cell cycle parameters were determined by monitoring DNA content of cumulus cell nuclei, collected under rigorously controlled conditions, by flow cytometry. The proportion of cumulus cells in three cell cycle-related populations (G0/G1; S; G2/M) was calculated before and after exposure to various experimental conditions in vivo or in vitro. About 30% of cumulus cells recovered from undifferentiated (compact) COC isolated 43-45 h after PMSG injections were in S phase and 63% were in G0/G1 (2C DNA content). Less than 10% of the cells were in the G2/M population. Cell cycle profiles of cumulus cells recovered from mucified COC (oviducal) after PMSG+hCG-induced ovulation varied markedly from those collected before hCG injection and were characterized by the relative absence of S-phase cells and an increased proportion of cells in G0/G1. Cell cycle profiles of cumulus cells collected from mucified COC recovered from mouse ovarian follicles before ovulation (9-10 h after hCG) were also characterized by loss of S-phase cells and an increased G0/G1 population. Results suggest that changes in cell cycle parameters in vivo are primarily mediated in response to physiological changes that occur in the intrafollicular environment initiated by the ovulatory stimulus. A similar lack of S-phase cells was observed in mucified cumulus cells collected 24 h after exposure in vitro of compact COC to dibutyryl cyclic adenosine monophosphate (DBcAMP), follicle-stimulating hormone or epidermal growth factor (EGF). Additionally, the proportion of cumulus cells in G2/M was enhanced in COC exposed to DBcAMP, suggesting that cell division was inhibited under these conditions. Thus, both the G1-->S-phase and G2-->M-phase transitions in the cell cycle appear to be amenable to physiological regulation. Time course studies revealed dose-dependent changes in morphology occurred within 6 h of exposure in vitro of COC to EGF or DBcAMP. Results suggest that the disappearance of the S-phase population is a consequence of a decline in the number of cells beginning DNA synthesis and exit of cells from the S phase following completion of DNA synthesis. Furthermore, loss of proliferative activity in cumulus cells appears to be closely associated with COC expansion and mucification, whether induced under physiological conditions in vivo or in response to a range of hormonal stimuli in vitro. The observations indicate that several signal-transducing pathways mediate changes in cell cycle parameters during cumulus cell differentiation.

scholarly journals In vitro and in vivo evaluation of antitrypanosomal activity of Annona muricata stem bark extracts.

2015 ◽  
Vol 61 (2) ◽  
pp. 50-62
Author(s):  
P.A. Onyeyili ◽  
K. Aliyoo
Keyword(s):  
Parasite Load ◽  
Stem Bark ◽  
Haematological Parameters ◽  
Bark Extract ◽  
Annona Muricata ◽  
In Vivo Evaluation ◽  
Trypanocidal Activity ◽  
Parasite Motility

Summary The control of trypanosomosis in animals and humans based on chemotherapy is limited and not ideal, since the agents used are associated with severe side effects, and emergence of relapse and drug resistant parasites. The need for the development of new, cheap and safe compounds stimulated this study. Three concentrations (211, 21.1 and 2.11 mg per ml) of chloroform stem bark extract of Annona muricata were screened for trypanocidal activity against Trypanosoma brucei brucei in vitro. Also, two doses (200 mg per kg and 100 mg per kg) of the extract were evaluated for trypanocidal activity in rats infected with the parasite. Haematological parameters were determined on day 1 post infection and on days 1, 6 and 30-post extract treatment. The extracts inhibited parasite motility and totally eliminated the organisms at the concentrations used in vitro. The extract also showed promising in vivo trypanocidal activity. The observed in vitro and in vivo trypanocidal activities may be due to the presence of bioactive compounds present in the extracts as seen in this study. The extract also improved the observed decreases in haematological parameters of the treated rats, which may be due to their ability to decrease parasite load. The observed oral LD50 of 1,725.05 mg per kg of the chloroform A. muricata extract using up and down method is an indication of very low toxicity, implying that the extract could be administered with some degree of safety.

Xeroderma Pigmentosum as a Model for Treatment of Bone Marrow Failure in Fanconi Anemia and Aplastic Anemia.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 4235-4235
Author(s):  
W. Clark Lambert ◽  
Santiago A. Centurion
Keyword(s):  
Cell Cycle ◽  
Bone Marrow ◽  
Fanconi Anemia ◽  
Xeroderma Pigmentosum ◽  
Bone Marrow Failure ◽  
S Phase ◽  
White Female ◽  
Cross Linking

Abstract We have previously shown that the primary cell cycle defect in the inherited, cancer-prone, bone marrow failure associated disease, Fanconi anemia (FA), is not in the G2 phase of the cell cycle, as had been thought for many years, but rather in the S phase. FA cells challenged with the DNA cross-linking agent, psoralen coupled with long wavelength, ultraviolet (UVA) radiation (PUVA), fail to slow their progression through the S phase of the subsequent cell cycle, as do normal cells. FA cells are extremely sensitive to the cytotoxic and clastogenic effects of DNA cross-linkers, such as PUVA, so much so that the diagnosis of FA is based on an assay, the “DEB test”, in which cells are examined for clastogenic and cytotoxic effects of diepoxybutane (DEB), a DNA cross-linking agent. More recently, we have shown that artificially slowing the cell cycle of FA cells exposed to PUVA by subsequent treatment with agents which slow their progression through S phase leads to markedly increased viability and reduced chromosome breakage in vitro. We now show that similar results can be obtained in vivo in patients with another DNA repair deficiency disease, xeroderma pigmentosum (XP), a recessively inherited disorder associated with defective repair of sunlight induced adducts in the DNA of sun-exposed tissues followed by development of numerous mutations causing large numbers of cancers in these same tissues. We treated two patients with XP, a light complected black male and a white female, both 14 years of age, in sun-exposed areas with 5-fluorouracil, an inhibitor of DNA synthesis, daily for three months. In contrast to normal patients, who only show clinical results if an inflammatory response is invoked, marked improvement in the clinical appearance of the skin was seen with no inflammation observed. This effect was confirmed histologically by examining epidermis adjacent to excised lesions in sun-exposed areas and further verified by computerized image analysis. Treatment with agents that slow progression through S phase, such as hydroxyurea, may similarly improve clinical outcomes in patients with FA or others who are developing bone marrow failure.

Thrombin Enhances Spontaneous Tumor Growth and Cell Cycle Activation by Downregulation of p27Kip1 and Upregulation of Skp2 and MiR-222

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 396-396
Author(s):  
Liang Hu ◽  
Sherif Ibrahim ◽  
Cynthia Liu ◽  
Jeffrey Skaar ◽  
Michelle Pagano ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Growth Factors ◽  
Cell Growth ◽  
Tumor Growth ◽  
Tumor Cell ◽  
Tumor Volume ◽  
S Phase ◽  
Down Regulation

Abstract Although it has been generally accepted that hypercoagulability contributes to enhancing tumor growth via generation of thrombin (Cancer Cell10:355, 2006), it has not been rigorously proven, nor has the mechanism been established at the cell cycle level. Previous studies have employed thrombin-treated tumor cell lines in vitro and in vivo. In vitro studies were performed in the presence of serum which contains a panoply of growth factors. In vivo studies have used huge non-pathologic concentrations of tumor cells injected into the flank, organ or blood of a mouse. In these situations, tumor growth could be a result of thrombin-induced angiogenesis. We therefore employed a transgenic mouse prostate cancer model (TRAMP) programmed to develop prostate CA over a period of 140–175 days. We treated these animals with thrombin to induce hypercoagulability or hirudin to inhibit endogenous thrombin production, to determine whether thrombin regulates this process independent of angiogenesis. Repetitive thrombin injection enhanced prostate tumor volume 6–8 fold (p<0.04). Repetitive hirudin decreased tumor volume 13–24 fold (p<0.04) via its effect on generated endogenous thrombin, n=6. Thrombin enhanced the production of several vascular growth factors and receptors 2.5 – 3 fold in the liver (VEGF, KDR, ANG-2, Tie2, GRO-1, CD31) and enhanced angiogenesis in the liver, n=3–4. Thrombin had no effect on tumor angiogenesis. Thus, the thrombin-induced spontaneous tumor growth was independent of angiogenesis. We next turned our attention to cell cycle regulators in serum-starved (72 hr) Go-synchronized LNcap prostate CA cells, employing Brdu and Propidium iodide staining. Addition of thrombin (0.5 u/ml) or its PAR-1 receptor agonist, TFLLRN (100 uM) had the same effect as androgen containing serum, inducing cells to leave Go, enter G1 and progress to S-phase. At 8 hrs the number of S-phase cells increased dramatically for both the serum (29 fold) as well as thrombin-treated cells (48 fold), n=3. Similar observations were noted in a Glioblastoma cell line, T98G. We further analyzed the effect of thrombin by performing immunoblots on cell cycle components mediated during cell growth and proliferation. In synchronized Go cells, levels of p27Kip1, a cyclin-dependent kinase inhibitor are high, while levels of cyclins D1 and A, the activation subunits for cyclin-dependent kinases are low. Both thrombin or serum addition led to down-regulation of p27Kip1 with concomitant induction of Skp2, the E3 ubiquitin ligase for p27Kip1. Cyclins D1 and A are induced by similar kinetics, indicating entry into S-phase by 8 hrs. Since p27Kip1 appears to be a rate-limiting down-regulator of the cell cycle (absent with high tumor grade and predicts poor prognosis), we confirmed its role by testing the effect of thrombin or TFLLRN by transfecting p27Kip1 in LNcap cells. This transfection completely prevented the cell cycle stimulation induced by these agonists. A similar approach was used with Skp2 knock down (KD), a negative down-regulator of p27Kip1. KD of Skp2 (over expressed in numerous cancers) completely prevented cell cycle progression induced by thrombin/TFLLRN. MiRNA 222 (upregulated in many cancers) is another down-regulator of p27Kip1. Further analysis following thrombin treatment revealed a robust upregulation at 4 and 8 hrs, providing further proof for the role of thrombin in down-regulating p27Kip1 and stimulating tumor cell entrance into S-phase. Thus, 1) Thrombin enhances spontaneous prostate cell growth in vivo in the absence of enhanced angiogenesis; 2) Thrombin activates the tumor cell cycle by stimulating the down-regulation of p27Kip1 through the upregulation of Skp2 and MiRNA 222.

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