cytochrome-c-t and pifithrin

 To explore the potential effect of miR-125b on p53-mediated regulation of Bax/Cytochrome C/Caspase-3 apoptotic signaling pathway in rats with cerebral ischemia-reperfusion (CIR) injury..  Sprague-Dawley (SD) rats were used to conduct CIR injury and injected with miR-125b mimic/inhibitor or p53 inhibitor (Pifithrin-α, PFT-α). Dual-luciferase reporter gene assay was used to analyze the targeting relationship between miR-125b and p53. Longa scoring and Triphenyl tetrazolinm chloride (TTC) staining were used to test the neurologic function and determine infarct size, respectively. Hematoxylin-eosin (HE) and Nissl's stainings were conducted to observe the morphology of cortical neurons. Neuronal nuclei (NeuN) expression was detected by immunohistochemical staining. QRT-PCR was performed to detect the expressions of miR-125b and p53. TUNEL staining and Western blotting was used to determine neuronal apoptosis and expressions of Bax/Cytochrome C/Caspase-3 signaling pathway-related proteins, respectively..  Our results showed that miR-125b could directly target p53. As observed, overexpression of miR-125b could obviously reduce the neurological score, infarct size, and brain water content after CIR in rats, which also improved the morphology of cortical neurons, increased the number of neurons, reduced neuronal apoptosis, and inhibited the expressions of Bax/Cytochrome C/Caspase-3 pathway. Moreover,the similar results were observed in rats with CIR after injected with PFT-α. But no significant differences in each index were found in CIR group and CIR + anti-miR-125b + PFT-α group.. MiR-125b exerts protective effects on CIR injury through inhibition of Bax/Cytochrome C/Caspase-3signaling pathway via targeting p53, which is likely to be a promising treatment for CIR.. 3'-UTR: 3-untranslated region; CIR: cerebral ischemia-reperfusion; CIS: cerebral ischemic stroke; PFT-α: Pifithrin-α; PVDF: polyvinylidene fluoride; SD: Sprague-Dawley; TBST: tris buffered saline with tween. TTC staining: Triphenyl tetrazolinm chloride staining; TUNEL: Terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling.

Topics: Animals; Apoptosis; bcl-2-Associated X Protein; Benzothiazoles; Brain Infarction; Brain Ischemia; Caspase 3; Caspases; Cytochromes c; Disease Models, Animal; Enzyme Inhibitors; Gene Expression Regulation; Male; MicroRNAs; Phosphopyruvate Hydratase; Rats; Rats, Sprague-Dawley; Reperfusion Injury; Signal Transduction; Toluene; Tumor Suppressor Protein p53

Granzyme B (GzmB) plays a major role in CTLs and NK cell-mediated elimination of virus-infected cells and tumors. Human GzmB preferentially induces target cell apoptosis by cleaving the proapoptotic Bcl-2 family member Bid, which, together with Bax, induces mitochondrial outer membrane permeabilization. We previously showed that GzmB also induces a rapid accumulation of the tumor-suppressor protein p53 within target cells, which seems to be involved in GzmB-induced apoptosis. In this article, we show that GzmB-activated p53 accumulates on target cell mitochondria and interacts with Bcl-2. This interaction prevents Bcl-2 inhibitory effect on both Bax and GzmB-truncated Bid, and promotes GzmB-induced mitochondrial outer membrane permeabilization. Consequently, blocking p53-Bcl-2 interaction decreases GzmB-induced Bax activation, cytochrome c release from mitochondria, and subsequent effector caspases activation leading to a decreased sensitivity of target cells to both GzmB and CTL/NK-mediated cell death. Together, our results define p53 as a new important player in the GzmB apoptotic signaling pathway and in CTL/NK-induced apoptosis.

Topics: Apoptosis; bcl-2-Associated X Protein; Benzothiazoles; BH3 Interacting Domain Death Agonist Protein; Caspase 3; Cell Line, Tumor; Cytochromes c; Enzyme Activation; Granzymes; Humans; Killer Cells, Natural; MCF-7 Cells; Mitochondria; Mitochondrial Membranes; RNA Interference; RNA, Small Interfering; T-Lymphocytes, Cytotoxic; Toluene; Tumor Suppressor Protein p53

In the present study, we sought to explore the mechanism of quercetin-induced apoptosis in rheumatoid arthritis fibroblast-like synoviocytes (RAFLSs). DNA fragmentation assay was used to detect quercetin-induced apoptosis in RAFLSs. The cleavages of caspase-3 and caspase-9 and the accumulation of cytosolic cytochrome C were measured by western blot in quercetin-treated RAFLSs. Mitochondrial membrane potential was tested by flow cytometry. Small interfering RNAs were used to knock down the expression of protein 53 (p53) and analyze the role of p53 in quercetin-induced apoptosis in RAFLSs. DNA fragmentation assay showed that quercetin dose-dependently elevated the apoptosis of RAFLSs, accompanying with enhanced caspase-3 and caspase-9 cleavages. Moreover, quercetin caused a concentration-dependent loss of mitochondrial membrane potential and cytochrome c release to cytosol and also decreased Bcl-2/Bax ratio, indicating that quercetin-induced apoptosis is through mitochondrial pathway. Quercetin also elevated p53 phosphorylation at ser15. Pretreatment with pifithrin-α, a p53 inhibitor, significantly diminished p53 phosphorylation at the concentration of 30 μM and abrogated quercetin-induced apoptosis in a dose-dependent manner. Quercetin-induced apoptosis was also significantly blocked by p53 silencing, further suggesting the involvement of p53 in quercetin-induced apoptosis in RAFLSs. Our study indicated that quercetin-induced apoptosis of RAFLSs is through mitochondrial pathway, in which p53 plays an important role.

Topics: Antioxidants; Apoptosis; Arthritis, Rheumatoid; bcl-2-Associated X Protein; Benzothiazoles; Caspase 3; Caspase 9; Cells, Cultured; Cytochromes c; DNA Fragmentation; Enzyme Activation; Fibroblasts; Humans; Membrane Potential, Mitochondrial; Phosphorylation; Proto-Oncogene Proteins c-bcl-2; Quercetin; RNA Interference; RNA, Small Interfering; Synovial Membrane; Toluene; Tumor Suppressor Protein p53

The PABPN1 [nuclear poly(A)-binding protein 1] is ubiquitous, binds to the nascent mRNA transcript and controls the poly(A) tract elongation process in multicellular organisms. Expansion of GCG repeats that encode first 6 of the 10 alanine residues of a polyalanine tract at the N-terminus of wild-type PABPN1 to 12-17 alanine residues causes aggregation of the protein and cell death. Patients with the adult onset autosomal dominant OPMD (oculopharyngeal muscular dystrophy) carry the GCG expansion mutation in their PABPN1 gene. The symptoms of OPMD include drooping eye lids and difficulty swallowing. The severity of symptoms increases with the length of the expansion. We have investigated the mechanism of cell death in HeLa and HEK-293 (human embryonic kidney) cultured cells expressing the mutant PABPN1 with a polyalanine tract containing 17 alanine residues (PABPN1-A17). In cells expressing PABPN1-A17, the abundance of pro-apoptotic proteins, p53, PUMA (p53 up-regulated modulator of apoptosis) and Noxa, are up-regulated. This was associated with the redistribution of p53 to the nucleus and mitochondria. Concomitantly Bax was translocated to the mitochondria, followed by the release of cytochrome c and the cleavage of caspase 3. Furthermore, blocking p53-mediated transcription using pifithrin significantly reduced apoptosis. Our findings suggest a key role of p53-mediated apoptosis in death of cells expressing the polyalanine expansion mutant of PABPN1.

Topics: Apoptosis; Apoptosis Regulatory Proteins; bcl-2-Associated X Protein; Benzothiazoles; Caspase 3; Cytochromes c; HEK293 Cells; HeLa Cells; Humans; Mitochondria; Muscular Dystrophy, Oculopharyngeal; Mutation; Peptides; Poly(A)-Binding Protein II; Proto-Oncogene Proteins; Proto-Oncogene Proteins c-bcl-2; Toluene; Tumor Suppressor Protein p53; Up-Regulation

P53 upregulated modulator of apoptosis (PUMA) plays an important role in mediating cell death. However, the role of PUMA in cardiomyocyte death induced by hypoxia/reoxygenation (H/R) and its molecular mechanism still remain enigmatic. Here, we used the in vitro model to elucidate the effects of PUMA on H/R-induced cardiomyocyte apoptosis as well as the underlying mechanisms. We reported that H/R could upregulate the expression of PUMA accompanied by the elevation of cardiomyocyte apoptosis. Interestingly, inhibition of endogenous PUMA expression by PUMA siRNA or p53 inhibitor repressed H/R-induced cardiomyocyte apoptosis. Furthermore, we found H/R stimulated the associations of PUMA apoptosis repressor with caspase recruitment domain (ARC) and consequently attenuated the associations of ARC with caspase 8, resulting in caspase 8 activation. Also, H/R stimulated cytochrome C release and caspase 3 activation. However, these stimulating effects of H/R disappeared upon knockdown of endogenous PUMA. Our data reveal that PUMA participates in H/R-triggered cardiomyocyte apoptosis by interfering with mitochondrial pathway.

Topics: Animals; Apoptosis; Apoptosis Regulatory Proteins; Benzothiazoles; Caspase 3; Caspase 8; Cells, Cultured; Cytochromes c; Hypoxia; Membrane Potential, Mitochondrial; Mitochondria, Heart; Muscle Proteins; Myocytes, Cardiac; Rats; Rats, Sprague-Dawley; Reperfusion Injury; Toluene

Mycotoxins produced by the Fusarium molds can cause a variety of human diseases and economic losses in livestock. Fusaria produce predominantly two types of mycotoxins: the nonestrogenic trichothecenes including T-2 toxin and the mycoestrogens such as zearalenone (ZEN). In a previous report, we demonstrated that the hepatotoxicity of these mycotoxins involves the mitochondrial pathway of apoptosis. Here, we observed that both fusarotoxins induced cell death by a mitochondria-dependent apoptotic process which includes opening of the mitochondrial permeability transition pore complex (PTPC), loss of mitochondrial transmembrane potential, increase in O(2)(.-) production, mitochondrial relocalization of Bax, cytochrome c release, and caspase activation. Studies performed on isolated mouse liver mitochondria showed that both ZEN and T-2 toxin might act directly on mitochondria to induce a PTPC-dependent permeabilization of mitochondrial membranes. Moreover, they may target different members of PTPC. Indeed, although the inner membrane protein adenine nucleotide translocase could be the target of T-2 toxin, ZEN seems to target the outer membrane protein voltage-dependent anion channel. Cells pretreatment with the p53 inhibitor pifithrin-alpha suggested that ZEN but not T-2 toxin triggered a p53-dependent mitochondrial apoptotic pathway. Finally, mitochondrial alterations induced by ZEN and T-2 toxin are mediated by Bcl-2 family proteins, such as Bax, and prevented by Bcl-x(L) and to a lesser extent by Bcl-2. Taken together, these data indicate that mitochondria play a pivotal role in both ZEN- and T-2 toxin-induced apoptosis and that PTPC members and proteins of Bcl-2 family should be interesting targets to overcome fusarotoxin toxicity.

Topics: Animals; Apoptosis; bcl-2-Associated X Protein; bcl-X Protein; Benzothiazoles; Caspase 3; Cell Survival; Cytochromes c; Dose-Response Relationship, Drug; Female; Fusarium; HCT116 Cells; HeLa Cells; Humans; Membrane Potential, Mitochondrial; Mice; Mice, Inbred C57BL; Mitochondria; Mitochondria, Liver; Mitochondrial Membrane Transport Proteins; Mitochondrial Permeability Transition Pore; Proto-Oncogene Proteins c-bcl-2; Signal Transduction; Superoxides; T-2 Toxin; Time Factors; Toluene; Tumor Suppressor Protein p53; Zearalenone

We have previously shown that when skeletal myoblasts are cultured in differentiation medium (DM), roughly 30% undergo caspase 3-dependent apoptosis rather than differentiation. Herein, we investigate the molecular mechanism responsible for the activation of caspase 3 and the ensuing apoptosis. When 23A2 myoblasts are cultured in DM, caspase 9 activity is increased and pharmacological abrogation of caspase 9 activation impairs caspase 3 activation and apoptosis. Further, we detect a time dependent release of mitochondrial cytochrome C into the cytosol in roughly 30% of myoblasts. Inclusion of cycloheximide inhibits the release of cytochrome C, the activation of caspase 9 and apoptosis. These data indicate that the mitochondrial pathway plays a role in this apoptotic process and that engagement of this pathway relies on de novo protein synthesis. Through RT-PCR and immunoblot analysis, we have determined that the expression level of the pro-apoptotic Bcl2 family member PUMA is elevated when 23A2 myoblasts are cultured in DM. Further, silencing of PUMA inhibits the release of cytochrome C and apoptosis. Signaling by the transcription factor p53 is not responsible for the increased level of PUMA. Finally, myoblasts rescued from apoptosis by either inhibition of elevated caspase 9 activity or silencing of PUMA are competent for differentiation. These results indicate a critical role for PUMA in the apoptosis associated with skeletal myoblast differentiation and that a p53-independent mechanism is responsible for the increased expression of PUMA in these cells.

Topics: Animals; Apoptosis; Apoptosis Regulatory Proteins; Benzothiazoles; Caspase 3; Caspase 9; Cell Differentiation; Culture Media; Cytochromes c; DNA Fragmentation; Enzyme Activation; Mice; Mitochondria; Myoblasts, Skeletal; Protein Biosynthesis; Proto-Oncogene Proteins c-bcl-2; Toluene; Tumor Suppressor Protein p53; Tumor Suppressor Proteins

Doxorubicin (Dox) is a chemotherapeutic agent that causes significant cardiotoxicity. We showed previously that Dox activates p53 and induces apoptosis in mouse hearts. This study was designed to elucidate the molecular events that lead to p53 stabilization, to examine the pathways involved in Dox-induced apoptosis, and to evaluate the effectiveness of pifithrin-alpha (PFT-alpha), a p53 inhibitor, in blocking apoptosis of rat H9c2 myoblasts. H9c2 cells that were exposed to 5 muM Dox had elevated levels of p53 and phosphorylated p53 at Ser15. Dox also triggered a transient activation of p38, p42/p44ERK, and p46/p54JNK MAP kinases. Caspase activity assays and Western blot analysis showed that H9c2 cells treated with Dox for 16 h had marked increase in the levels of caspases-2, -3, -8, -9, -12, Fas, and cleaved poly(ADP ribose) polymerase (PARP). There was a concomitant increase in p53 binding activity, cytochrome c release, and apoptosis. These results suggest that Dox can trigger intrinsic, extrinsic, and endoplasmic reticulum-associated apoptotic pathways. Pretreatment of cells with PFT-alpha followed by Dox administration attenuated Dox-induced increases in p53 levels and p53 binding activity and partially blocked the activation of p46/p54JNK and p42/p44ERK. PFT-alpha also led to decreased levels of caspases-2, -3, -8, -9, -12, Fas, PARP, cytochrome c release, and apoptosis. Our results suggest that p53 stabilization is a focal point of Dox-induced apoptosis and that PFT-alpha interferes with multiple steps of Dox-induced apoptosis.

Topics: Animals; Antibiotics, Antineoplastic; Apoptosis; Benzothiazoles; Blotting, Western; Caspases; Cell Line, Tumor; Cytochromes c; Doxorubicin; Electrophoretic Mobility Shift Assay; Energy Metabolism; Enzyme Activation; Enzyme-Linked Immunosorbent Assay; fas Receptor; Genes, p53; Mitogen-Activated Protein Kinases; Myocardium; Neoplasms, Muscle Tissue; Oxidative Stress; Phosphorylation; Poly(ADP-ribose) Polymerases; Rats; Thiazoles; Toluene

Silibinin, a natural flavonolignan, induces apoptosis in human bladder transitional-cell papilloma RT4 cells both in vitro and in vivo; however, mechanisms of such efficacy are not completely identified. Here, we studied the mechanisms involved in silibinin-induced apoptosis of RT4 cells having intact p53. Silibinin increased p53 protein level together with its increased phosphorylation at serine 15, activated caspase cascade and caused Bid cleavage for apoptosis. Silibinin-caused p53 activation was mediated via ATM-Chk2 pathway, which in turn induced caspase 2-mediated apoptosis. Pifithrin-alpha, a p53 inhibitor, reversed silibinin-induced caspase activation including caspase 2; however, caspase 2 inhibitor also reversed p53 phosphorylation suggesting a bidirectional regulation between them. Further, silibinin caused a rapid translocation of p53 and Bid into mitochondria leading to increased permeabilization of mitochondrial membrane and cytochrome c release into the cytosol. JNK1/2 activation was observed as a connecting link for p53-mediated caspase 2 activation. Interestingly, silibinin-induced apoptosis was mediated, in part, via Cip1/p21 cleavage by caspase, which was reversed by Cip1/p21 siRNA. Together, these results suggested the novel mechanisms for apoptosis induction by silibinin involving p53-caspase 2 activation and caspase-mediated cleavage of Cip1/p21.

Topics: Apoptosis; Benzothiazoles; Caspase 2; Cell Line, Tumor; Cyclin-Dependent Kinase Inhibitor p21; Cytochromes c; Enzyme Inhibitors; Gene Expression Regulation, Neoplastic; Humans; Mitochondria; Models, Biological; Silybin; Silymarin; Toluene; Tumor Suppressor Protein p53; Urinary Bladder Neoplasms

Oxidative stress has been implicated in the pathogenesis of stroke, traumatic brain injuries, and neurodegenerative diseases affecting both neuronal and glial cells in the central nervous system (CNS). The tumor suppressor protein p53 plays a pivotal function in neuronal apoptosis triggered by oxidative stress. We investigated the role of p53 and related molecular mechanisms that support oxidative stress-induced apoptosis in glia. For this purpose, we exposed C6 glioma cells and primary cultures of rat cortical astrocytes to an H(2)O(2)-induced oxidative stress protocol followed by a recovery period. We evaluated the effects of pifithrin-alpha (PF-alpha), which has been reported to protect neurons from ischemic insult by specifically inhibiting p53 DNA-binding activity. Strikingly, PF-alpha was unable to prevent oxidative stress-induced astrocyte apoptosis. We demonstrate that p53 is able to mediate an apoptotic response by direct signaling at mitochondria, despite its transcriptional activity. The z-VAD-fmk-sensitive apoptotic response requires a caspase-dependent MDM-2 degradation, leading to p53 mitochondrial targeting accompanied by cytochrome c release and nucleosomal fragmentation.

Topics: Amino Acid Chloromethyl Ketones; Animals; Apoptosis; Astrocytes; Benzothiazoles; Blotting, Northern; Cell Survival; Cells, Cultured; Cytochromes c; Embryo, Mammalian; Fluorescent Antibody Technique; Genes, bcl-2; Hydrogen Peroxide; Microscopy, Confocal; Mitochondria; Models, Biological; Neuroprotective Agents; Nuclear Proteins; Nucleosomes; Oxidants; Oxidative Stress; Proto-Oncogene Proteins; Proto-Oncogene Proteins c-mdm2; Rats; Recovery of Function; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Thiazoles; Time Factors; Toluene; Tumor Suppressor Protein p53

Stimulation of the activity of deoxycytidine kinase (dCK), the principal deoxynucleoside salvage enzyme, has been recently considered as a protective cellular response to a wide range of agents interfering with DNA repair and apoptosis. In light of this, the potential contribution of dCK activation to apoptosis induction--presumably by supplying dATP or its analogues for the apoptosome formation--deserves consideration. Two-hour exposure of human tonsillar lymphocytes to 2-chloro-deoxyadenosine (CdA) led to a two-fold activation of dCK. This activation process was inhibited by pifithrin-alpha, a potent inhibitor of p53. When the dNTP pools were determined, both deoxypyrimidine triphosphate and dGTP pools were reduced after the treatments, while dATP levels elevated by 62%, 77% and 50% in the CdA, aphidicolin and etoposide-treated cells, respectively. We assume that dCK activation elicited by cellular damage might be a proapoptotic factor in terms of generating dATP well before the release of cytochrome c and deoxyguanosine kinase from mitochondria.

Topics: Adenosine Triphosphate; Antineoplastic Agents; Apoptosis; Benzothiazoles; Cells, Cultured; Cladribine; Cytochromes c; Deoxycytidine Kinase; DNA Repair; Dose-Response Relationship, Drug; Enzyme Activation; Humans; Lymphocytes; Models, Biological; Palatine Tonsil; Phosphotransferases (Alcohol Group Acceptor); Thiazoles; Toluene; Tumor Suppressor Protein p53

Current evidence suggests that amyloid beta peptides (Abeta) may play a major role in the pathogenesis of Alzheimer's disease by eliciting oxidative stress and neuronal apoptosis. In this study we have used differentiated SK-N-BE neurons to investigate molecular mechanisms and regulatory pathways underlying apoptotic neuronal cell death elicited by Abeta(1-40) and Abeta(1-42) peptides as well as the relationships between apoptosis and oxidative stress. Abeta peptides, used at concentrations able to induce oxidative stress, elicit a classic type of neuronal apoptosis involving mitochondrial regulatory proteins and pathways (i.e. affecting Bax and Bcl-2 protein levels as well as release of cytochrome c in the cytosol), poly-ADP rybose polymerase cleavage and activation of caspase 3. This pattern of neuronal apoptosis, that is significantly prevented by alpha-tocopherol and N-acetylcysteine and completely abolished by specific inhibitors of stress-activated protein kinases (SAPK) such as JNKs and p38(MAPK), involved early elevation of p53 protein levels. Pretreatment of neurons with alpha-pifithrin, a specific p53 inhibitor, resulted in a 50-60% prevention of Abeta induced apoptosis. These results suggest that oxidative stress - mediated neuronal apoptosis induced by amyloid beta operates by eliciting a SAPK-dependent multiple regulation of pro-apoptotic mitochondrial pathways involving both p53 and bcl-2.

Topics: Acetylcysteine; alpha-Tocopherol; Amyloid beta-Peptides; Apoptosis; bcl-2-Associated X Protein; Benzothiazoles; Caspase 3; Caspases; Cell Differentiation; Cytochromes c; Enzyme Activation; Enzyme Inhibitors; Humans; Hydrogen Peroxide; JNK Mitogen-Activated Protein Kinases; MAP Kinase Kinase 4; Mitochondria; Mitogen-Activated Protein Kinase Kinases; Mitogen-Activated Protein Kinases; Neuroblastoma; Oxidative Stress; p38 Mitogen-Activated Protein Kinases; Peptide Fragments; Poly(ADP-ribose) Polymerases; Proto-Oncogene Proteins; Proto-Oncogene Proteins c-bcl-2; Thiazoles; Toluene; Tumor Cells, Cultured; Tumor Suppressor Protein p53

Previously, we have identified aloe-emodin (AE) as a new type of anticancer agent, with activity that is based on apoptotic cell death promoted by a neuroectodermal tumor-specific drug uptake. We attempt to clarify the intracellular target of AE and the apoptosis-signaling pathway activated by AE in neuroblastoma cell lines. Two-photon excitation microscopy and spectroscopic titrations documented that AE is highly concentrated in susceptible cells and binds to DNA. One of the most important mediators of apoptotic response to genotoxic stimuli, such as anticancer agents, is the p53 tumor suppressor gene. To evaluate the role played by p53 in AE-induced apoptosis a p53 mutant cell line, which lacks transcriptional activity of p53 targeted genes, was tested. AE displayed a reduced growth inhibitory and pro-apoptotic activity in p53 mutant cells (SK-N-BE(2c)) with respect to the p53 wild-type line (SJ-N-KP). This effect was not caused by a reduced drug uptake in the mutant neuroblastoma cell line but was related to a different apoptotic cell phenotype. Whereas SJ-N-KP cells were susceptible to a p53 transcription-dependent pathway of apoptosis, SK-N-BE(2c) cells underwent apoptosis with up-regulation of p53 expression but not of p53-target genes. After AE treatment p53 translocates to the mitochondria inter-membrane space in both neuroblastoma cell lines. Due to its high accumulation in neuroectodermal tumor cells AE could also kill tumor cells harboring p53 mutant genes. This property would further contribute to AE specific anti-tumor activity and might be exploitable in the clinic.

Topics: Anthraquinones; Apoptosis; Benzothiazoles; Blotting, Western; Caspases; Cell Cycle; Child, Preschool; Cytochromes c; DNA Primers; DNA Topoisomerases, Type II; DNA, Neoplasm; Emodin; Enzyme Inhibitors; Gene Expression Regulation, Neoplastic; Genes, bcl-2; Humans; Male; Microscopy, Immunoelectron; Mitochondria; Mutation; Neuroectodermal Tumors; Poly(ADP-ribose) Polymerases; Protein Transport; Reverse Transcriptase Polymerase Chain Reaction; Thiazoles; Toluene; Tumor Cells, Cultured; Tumor Suppressor Protein p53