p38 MAPK activation, JNK inhibition, neoplastic growth inhibition, and increased gap junction communication in human lung carcinoma and Ras-transformed cells by 4-phenyl-3-butenoic acid.
ABSTRACT Human lung neoplasms frequently express mutations that down-regulate expression of various tumor suppressor molecules, including mitogen-activated protein kinases such as p38 MAPK. Conversely, activation of p38 MAPK in tumor cells results in cancer cell cycle inhibition or apoptosis initiated by chemotherapeutic agents such as retinoids or cisplatin, and is therefore an attractive approach for experimental anti-tumor therapies. We now report that 4-phenyl-3-butenoic acid (PBA), an experimental compound that reverses the transformed phenotype at non-cytotoxic concentrations, activates p38 MAPK in tumorigenic cells at concentrations and treatment times that correlate with decreased cell growth and increased cell-cell communication. H2009 human lung carcinoma cells and ras-transformed rat liver epithelial cells treated with PBA showed increased activation of p38 MAPK and its downstream effectors which occurred after 4 h and lasted beyond 48 h. Untransformed plasmid control cells showed low activation of p38 MAPK compared to ras-transformed and H2009 carcinoma cells, which correlates with the reduced effect of PBA on untransformed cell growth. The p38 MAPK inhibitor, SB203580, negated PBA's activation of p38 MAPK downstream effectors. PBA also increased cell-cell communication and connexin 43 phosphorylation in ras-transformed cells, which were prevented by SB203580. In addition, PBA decreased activation of JNK, which is upregulated in many cancers. Taken together, these results suggest that PBA exerts its growth regulatory effect in tumorigenic cells by concomitant up-regulation of p38 MAPK activity, altered connexin 43 expression, and down-regulation of JNK activity. PBA may therefore be an effective therapeutic agent in human cancers that exhibit down-regulated p38 MAPK activity and/or activated JNK and altered cell-cell communication.
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ABSTRACT: Summary BACKGROUND AND PURPOSE: The Maillard Reaction Products (MRPs) are known to be effective in chemoprevention. Here we focused on the anti-cancer mechanism of (E)-2, 4-bis (p-hydroxyphenyl)-2-butenal (MRP), in a concentrations (10-40 μg/ml) and time (30 min-72 h) dependent manner on the human non-small-cell lung cancer (NSCLC)cells (NCI-H460 and A549). EXPERIMENTAL APPROACH: Here we analyzed the activity by, western blot for major apoptotic protein, MAPK, NF-κB and death receptor expression, RT-PCR for death receptor mRNA expression, EMSA for NF-κB DNA binding activity and effect of inhibitors by colony formation assay. KEY RESULTS: Our studies show that this compound has a concentration- and time-dependent inhibitory effect on the growth of NSCLC cells due to induction of apoptosis. Concomitantly, there is also a significant increase in apoptotic proteins like cleaved caspase-3, cleaved caspase-9, Bax and p53 but down regulation of anti-apoptotic proteins like Bcl-2, cIAP1 and cIAP2. This activity is due to up regulation of mitogen-activated protein kinases (MAPK) and death receptor (DR) proteins like DR3, DR5 and DR6, but inactivation of nuclear transcriptional factor-κB (NF-κB). Among the all DR activated, only DR5 knock down with siRNA reversed the effect. Even though all MAPKinases are activated, only the pre-treatment of p38 MAPKinase inhibitor reversed (E)-2, 4-bis (p-hydroxyphenyl)-2-butenal-induced cell growth inhibition, cleaved caspase-3, -9 and DR5 expression, NF-κB inactivation. CONCLUSIONS AND IMPLICATIONS: Thus, these data show that p38 MAPK mediated NF-κB and DR5 signals are critical in the anti-cancer activity of (E)-2, 4-bis (p-hydroxyphenyl)-2-butenal.British Journal of Pharmacology 10/2012; · 5.07 Impact Factor
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ABSTRACT: Infrasonic noise/infrasound is a type of environmental noise that threatens public health as a nonspecific biological stressor. Glutamate-related excitotoxicity is thought to be responsible for infrasound-induced impairment of learning and memory. In addition to neurons, astrocytes are also capable of releasing glutamate. In the present study, to identify the effect of infrasound on astroglial glutamate release, cultured astrocytes were exposed to infrasound at 16 Hz, 130 dB for different times. We found that infrasound exposure caused a significant increase in glutamate levels in the extracellular fluid. Moreover, blocking the connexin43 (Cx43) hemichannel or gap junction, decreasing the probability of Cx43 being open or inhibiting of Cx43 expression blocked this increase. The results suggest that glutamate release by Cx43 hemichannels/gap junctions is involved in the response of cultured astrocytes to infrasound.Neurochemical Research 03/2014; · 2.13 Impact Factor
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ABSTRACT: HYS-32 [4-(3,4-dimethoxyphenyl)-3-(naphthalen-2-yl)-2(5H)-furanone] is a new analogue of the anti-tumor compound combretastatin A-4 containing a cis-stilbene moiety. In this study, we investigated its effects on Cx43 gap junction intercellular communication (GJIC) and the signaling pathway involved in rat primary astrocytes. Western blot analyses showed that HYS-32 dose- and time-dependently upregulated Cx43 expression. A confocal microscopic study and scrape-loading/dye transfer analyses demonstrated that HYS-32 (5 μM) induced microtubule coiling, accumulation of Cx43 in gap junction plaques, and increased GJIC in astrocytes. The HYS-32-induced microtubule coiling and Cx43 accumulation in gap junction plaques was reversed when HYS-32 was removed. Treatment of astrocytes with cycloheximide resulted in time-dependent degradation of Cx43, which was delayed by co-treatment with HYS-32 by increasing the half-life of Cx43. Co-treatment with HYS-32 also prevented the LPS-induced downregulation of Cx43 and inhibition of GJIC in astrocytes. HYS-32 induced activation of PKC, ERK, and JNK, and co-treatment with the PKC inhibitor Go6976 or the ERK inhibitor PD98059, but not the JNK inhibitor SP600125, prevented the HYS-32-induced increase in Cx43 expression and GJIC. Go6976 suppressed the HYS-32-induced PKC phosphorylation and increase in phospho-ERK levels, while PD98059 did not prevent the HYS-32-induced increase in phospho-PKC levels, suggesting that PKC is an upstream effector of ERK. In conclusion, our results show that HYS-32 increases the half-life of Cx43 and enhances Cx43 expression and GJIC in astrocytes via a PKC-ERK signaling cascade. These novel biological effects of HYS-32 on astrocyte gap junctions support its potential for therapeutic use as a protective agent for the central nervous system.Neurochemistry International 03/2013; · 2.66 Impact Factor