Thymoquinone attenuates doxorubicin‐cardiotoxicity in rats

Contrary to the fact that doxorubicin is a powerful chemotherapeutic agent for the treatment of neoplastic diseases, cardiotoxicity is too important to be ignored. Thymoquinone serves as a powerful free radical scavenger. In the study, the effects of thymoquinone against doxorubicin‐cardiotoxicity will be evaluated. Forty rats were divided into five groups. Group I: control group (n = 8); group II: olive oil group (n = 8); group III: thymoquinone group (n = 8); given 10 mg/kg thymoquinone intraperitoneally per day throughout the experiment; group IV: doxorubicin group (n = 8); injected with a single dose of 15 mg/kg ip doxorubicin on the 7th day of the experiment; group V: doxorubicin + thymoquinone group (n = 8); administered with 10 mg/kg thymoquinone per day during the experiment and 15 mg/kg doxorubicin ip on the 7th day. The experiment was planned for 14 days. Immunohistochemically, heat shock protein (HSP) 70 and HSP90, glucose‐regulated protein 78 (GRP78), caspase‐3 were stained. We made terminal deoxynucleotidyl transferase dUTP nick end labeling for apoptotic evaluation. Total oxidant status (TOS) levels and total antioxidant status (TAS) were measured in the heart tissue. Atrial natriuretic peptide (ANP) and pro‐B type natriuretic peptide (proBNP) were evaluated. In the study, HSP70, HSP90, GRP78, and caspase‐3 levels increased in group IV. TOS and TAS levels were significant compared to group I. Doxorubicin significantly increased ANP and NT‐proBNP levels. Thymoquinone revealed significant differences in these values. Thymoquinone can be an important cardioprotective agent against doxorubicin‐cardiotoxicity.     

Role of oxidative stress in geldanamycin-induced cytotoxicity and disruption of Hsp90 signaling complex

Heat shock protein 90 (Hsp90) is a chaperone protein regulating PC-12 cell survival by binding and stabilizing Akt, Raf-1, and Cdc37. Hsp90 inhibitor geldanamycin (GA) cytotoxicity has been attributed to the disruption of Hsp90 binding, and the contribution of oxidative stress generated by its quinone group has not been studied in this context. Reactive oxygen species (ROS) and cell survival were assessed in PC-12 cells exposed to GA or menadione (MEN), and Akt, Raf-1, and Cdc37 expression and binding to Hsp90 were determined. GA disrupted Hsp90 binding and increased ROS production starting at 1 h, and cell death occurred at 6 h, inhibited by N-acetylcysteine (NAC) without preventing dissociation of proteins. At 24 h, NAC prevented cytotoxicity and Hsp90 complex disruption. However, MnTBAP antioxidant treatment failed to inhibit GA cytotoxicity, suggesting that NAC acts by restoring glutathione. In contrast, 24 h MEN treatment induced cytotoxicity without disrupting Hsp90 binding. GA and MEN decreased Hsp90-binding protein expression, and proteasomal inhibition prevented MEN-, but not GA-induced degradation. In conclusion, whereas MEN cytotoxicity is mediated by ROS and proteasomal degradation, GA-induced cytotoxicity requires ROS but induces Hsp90 complex dissociation and proteasome-independent protein degradation. These differences between MEN- and GA-induced cytotoxicity may allow more specific targeting of cancer cells.     

Characterizing the polymeric status of Helicobacter pylori heat shock protein 60

Helicobacter pylori heat shock protein 60 (HpHsp60) was first identified as an adhesion molecule associated with H. pylori infection. Here we have analyzed the structure of HpHsp60 via amino acid BLAST, circular dichroism, and electrophoresis and the results indicate that most recombinant HpHsp60 molecules exist as dimers or tetramers, which is quite different from Escherichia coli Hsp60. Treatment of human monocytic cells THP-1 with HpHsp60 was found to up-regulate a panel of cytokines including IL-1α, IL-8, IL-10, IFN-γ, TNF-α, TGF-β, GRO, and RANTES. Carboxymethylated HpHsp60 molecules with a switched oligomeric status were able to further enhance NF-κB-mediated IL-8 and TNF-α secretion in THP-1 cells compared to unmodified HpHsp60 molecules. These results indicated that the oligomeric status of HpHsp60s might have an important role in regulating host inflammation and thus help facilitate H. pylori persistent infection.     

Activation of transgene expression in skeletal muscle by focused ultrasound

To correlate thermal dose from focused ultrasound (FUS) with gene expression and tissue injury, a temperature plateau strategy was employed. Plasmids encoding luciferase gene under the control of hsp70B promoter were transfected into the right gastrocnemius muscle in a rat via electroporation. One day after transfection, hind limbs were treated with 3.3-MHz focused ultrasound, using one of four different temperature plateaus with spatial-peak time-average focal temperatures (T_SPTA) of 46 °C, 48 °C, 51 °C and 62 °C. The treatment duration at the plateau temperature was varied from 0 to 30 s. Gene expression was analyzed in vivo one day following FUS treatment, and H&E staining was employed to assess tissue injury. Gene activation and tissue damage correlated closely with thermal dose. The highest level of gene activation was induced by FUS at T_SPTA = 51 °C for 20 s, which was found to be statistically equivalent to that produced by water-bath hyperthermia.     

Molecular cloning and characterization of novel heat shock protein 90 gene from a wild <Emphasis Type="Italic">Vitis pseduoreticulata</Emphasis> native to China

Heat shock protein 90 (Hsp90), known as molecular chaperone, is involved in protein folding and assembly in the cell. In the present study, a full-length cDNA named Vitis pseduoreticulta heat shock protein 90 (VpHsp90) (GenBank accession Number:EU239815), encoding a heat shock protein 90, was obtained by degenerated primers and 3′-and 5′-RACE from Vitis pseudoreticulata according to our previously obtained EST sequence (GenBnak accession number:DV182112), putatively known as Hsp90. Comparison of VpHsp90 sequence has revealed that an open reading frame (ORF) consists of 2,100 bp nucleotides and the translated proteins of 699 amino acid residues. The molecular mass of VpHsp90 calculated from the deduced amino acid sequence was 80.2 kDa, Isolectric Point was 4.893, which is in close proximity of Hsp90. The maximum similarity of VpHsp90 at nucleotides level (85%) and protein level (96%) was found to be with Nicotiana tabacum. Phylogenetic tree analysis at both the nucleotides and amino acids levels indicates that Vitis pseduoreticulata, Nicotiana tabacum, and Arabidopsis thaliana Hsp90 sequences comprise one clade, which is closely related to Oryza sativa, Hordeum vulgare and Triticum aestivum Hsp90s. It may be reasonably concluded that VpHsp90 possesses the ancestral gene of Hsp90 similar to that of higher plant species.