A method for the quantitative analysis of human heat shock gene expression using a multiplex RT-PCR assay

Dietary Supplementation of Potential Probiotics Bacillus subtilis, Bacillus licheniformis, and Saccharomyces cerevisiae and Synbiotic Improves Growth Performance and Immune Responses by Modulation in Intestinal System in Broiler Chicks Challenged with Salmonella Typhimurium

This study evaluates the effects of probiotics and synbiotics on the performance, immune responses, and intestinal morphology, and the expression of immunity-related genes of broiler chicks challenged with Salmonella typhimurium. Three hundred and sixty broiler chicks were divided into six groups, including broiler chicks challenged and non-challenged with S. typhimurium and fed with probiotic, synbiotic, and basal diet without additive. Growth performance (food intake, daily gain, feed conversion ratio, and mortality), immune responses (antibody titer against sheep red blood cells, immunoglobulins G and M), intestinal morphology, lactic acid bacteria population, and the expression of immunity-related genes (interferon-γ, interleukins 6 and 12, and tumor necrosis factor-α) were investigated. The administration of S. typhimurium decreased growth performance (P = 0.0001), immune responses (P = 0.0001), intestinal morphology (P = 0.0001), lactic acid bacteria population (P = 0.0001), and the expression of immunity-related genes (P = 0.0001) of broiler chickens. However, broiler chicks fed with probiotic (P = 0.001) and synbiotic (P = 0.0001) showed better growth performance, immune responses, intestinal morphology, lactic acid bacteria population, and the expression of immunity-related genes in comparison with infected broiler chicks fed with basal diet lack of probiotic and synbiotic. Feeding probiotics (P = 0.001) and synbiotics (P = 0.0001) showed positive effects for challenged and non-challenged broiler chicks. In sum, feeding synbiotic and probiotic alleviated the negative effects of S. typhimurium on growth and immunity of broiler chicks. It can be suggested to apply synbiotic and probiotics as benefit additive against infectious challenges, such as S. typhimurium.

Verification of Non-thermal Effects of 0.3–0.6 THz-Waves on Human Cultured Cells

Recent progress has been made in the development of terahertz (THz) waves for practical applications. Few studies that have assessed the biological effects of THz waves have been reported, and the data currently available regarding the safety of THz waves is inadequate. In this study, the effect of THz wave exposure on two cultured cells was assessed using a widely tunable THz source with a 0.3–0.6 THz frequency range, which can be used and increased in one GHz increments. The THz waves applied to the cultured cells were weak enough such that any thermal effects could be disregarded. The influence of THz wave exposure on both the proliferative and metabolic activities of these cells was investigated, as well as the extent of the thermal stress placed on the cells. In this work, no measurable effect on the proliferative or metabolic activities of either cell type was observed following the exposure to THz waves. No differences in the quantity of cDNA related to heat shock protein 70 was detected in either the sham or exposure group. As such, no differences in cellular activity between cells exposed to THz waves and those not exposed were observed.

Development and evaluation of multiplex PCR assays for rapid detection of virulence-associated genes in Arcobacter species

As the pathogenicity of Arcobacter species might be associated with various virulence factors, this study was aimed to develop and optimize three single-tube multiplex PCR (mPCR) assays that can efficiently detect multiple virulence-associated genes (VAGs) in Arcobacter spp. including the Arcobacter butzleri, Arcobacter cryaerophilus and Arcobacter skirrowii, respectively. The recognized target virulence factors used in the study were fibronectin binding protein (cj1349), filamentous hemagglutinin (hecA), hemolysin activation protein (hecB), hemolysin (tlyA), integral membrane protein virulence factor (mviN), invasin (ciaB), outer membrane protein (irgA) and phospholipase (pldA). Identical results were obtained between singleplex PCR and mPCR assays and no cross- and/or non-specific amplification products were obtained when tested against other closely related bacterial species. The sensitivities of these three mPCR assays were ranging from 1ngμL(-1) to 100ngμL(-1) DNA. The developed assays with combinations of duplex or triplex PCR primer pairs of VAGs were further evaluated and validated by applying them to isolates of the A. butzleri, A. cryaerophilus and A. skirrowii recovered from fecal samples of human and animal origins. The findings revealed that the distribution of the ciaB (90%), mviN (70%), tlyA (50%) and pldA (45%) genes among these target species was significantly higher than the hecA (16%), hecB (10%) and each of irgA and cj1349 (6%) genes, respectively. The newly developed mPCR assays can be used as rapid technique and useful markers for the detection, prevalence and profiling of VAGs in the Arcobacter spp. Moreover, these assays can easily be performed with a high throughput to give a presumptive identification of the causal pathogen in epidemiological investigation of human infections.

Quantitative proteomics of heat-treated human cells show an across-the-board mild depletion of housekeeping proteins to massively accumulate few HSPs

Classic semiquantitative proteomic methods have shown that all organisms respond to a mild heat shock by an apparent massive accumulation of a small set of proteins, named heat-shock proteins (HSPs) and a concomitant slowing down in the synthesis of the other proteins. Yet unexplained, the increased levels of HSP messenger RNAs (mRNAs) may exceed 100 times the ensuing relative levels of HSP proteins. We used here high-throughput quantitative proteomics and targeted mRNA quantification to estimate in human cell cultures the mass and copy numbers of the most abundant proteins that become significantly accumulated, depleted, or unchanged during and following 4 h at 41 °C, which we define as mild heat shock. This treatment caused a minor across-the-board mass loss in many housekeeping proteins, which was matched by a mass gain in a few HSPs, predominantly cytosolic HSPCs (HSP90s) and HSPA8 (HSC70). As the mRNAs of the heat-depleted proteins were not significantly degraded and less ribosomes were recruited by excess new HSP mRNAs, the mild depletion of the many housekeeping proteins during heat shock was attributed to their slower replenishment. This differential protein expression pattern was reproduced by isothermal treatments with Hsp90 inhibitors. Unexpectedly, heat-treated cells accumulated 55 times more new molecules of HSPA8 (HSC70) than of the acknowledged heat-inducible isoform HSPA1A (HSP70), implying that when expressed as net copy number differences, rather than as mere "fold change" ratios, new biologically relevant information can be extracted from quantitative proteomic data. Raw data are available via ProteomeXchange with identifier PXD001666.

Mild hyperthermia enhances the expression and induces oscillations in the Dicer protein

PURPOSE

To investigate whether mild heat stress at 39.5°C altered Dicer protein and miRNA expression patterns in several cell types.

METHODS

Multiple human and mouse cell types were cultured during the course of 9 h at temperatures from 37°C to 39.5°C. Dicer mRNA levels and microRNAs were quantified by TaqMan RT-qPCR assays and Dicer protein by western blotting.

RESULTS

Dicer protein was substantially elevated on western analysis in response to heat stress at 39.5°C in the absence of significant changes in Dicer mRNA by RT-qPCR.

CONCLUSIONS

Heat-induced regulation of Dicer expression occurs primarily post- transcriptionally, and the expression levels of Dicer protein are increased and often oscillate in response to fever-range hyperthermia in multiple mouse and human cells. Our studies suggest a potential role for Dicer and microRNAs in the response to mild thermal stress. Additional studies on the mechanisms involved in the stress-induced oscillations of Dicer protein and microRNAs will be of interest.

Hyperthermia potentiates oncolytic herpes viral killing of pancreatic cancer through a heat shock protein pathway

BACKGROUND

Oncolytic herpes simplex virus-1 (HSV-1) is designed to specifically infect, replicate in, and lyse cancer cells. This study investigates a novel therapeutic regimen, combining the effects of NV1066 (a recombinant HSV-1) and hyperthermia in the treatment of pancreatic cancer.

METHODS

NV1066 is an attenuated HSV-1 that replicates in cells resistant to apoptosis. Heat shock protein 72 (Hsp72) is a member of a family of proteins that is upregulated after hyperthermic insult, lending cellular protection by inhibiting apoptosis. In these experiments, we test the hypothesis that increased Hsp72 expression in response to hyperthermia enhances anti-apoptotic mechanisms, thereby increasing viral replication and tumor cell kill. Hs 700T pancreatic cancer cells were treated with hyperthermia alone (42 degrees C), NV1066 alone, and combination therapy. Cell survival and viral growth were measured. The effect of siRNA-directed Hsp72 knockdown was also measured.

RESULTS

Combining hyperthermia and viral treatment produced a synergistic effect on cell kill. Viral growth increased greater than 6-fold in the presence of hyperthermia (P < .05). Hyperthermia alone showed minimal cytotoxic activity against Hs 700T cells, while NV1066 infection resulted in approximately 50% cell kill. The combination of hyperthermia and viral infection significantly increased cell kill to approximately 80% (P < .01). Hsp72 knockdown attenuated this synergistic effect.

CONCLUSION

Hyperthermia enhances NV1066 replication, thereby potentiating the viral oncolytic response against pancreatic cancer cells. This finding has potential clinical application in the use of heated perfusion or permissive hyperthermia for delivery of oncolytic viral therapies.

HSP70 expression in human trophoblast cells exposed to different 1.8 Ghz mobile phone signals

The heat-shock proteins (HSPs) are important cellular stress markers and have been proposed as candidates to infer biological effects of high-frequency electromagnetic fields (EMFs). In the current study, HSP70 gene and protein expression were evaluated in cells of the human trophoblast cell line HTR-8/SVneo after prolonged exposure (4 to 24 h) to 1.8 GHz continuous-wave (CW) and different GSM signals (GSM-217Hz and GSM-Talk) to assess the possible effects of time and modulation schemes on cell responses. Inducible HSP70 protein expression was not modified by high-frequency EMFs under any condition tested. The inducible HSP70A, HSP70B and the constitutive HSC70 transcripts did not change in cells exposed to high-frequency EMFs with the different modulation schemes. Instead, levels of the inducible HSP70C transcript were significantly enhanced after 24 h exposure to GSM-217Hz signals and reduced after 4 and 16 h exposure to GSM-Talk signals. As in other cell systems, in HTR-8/SVneo cells the response to high-frequency EMFs was detected at the mRNA level after exposure to amplitude-modulated GSM signals. The present results suggest that the expression analysis for multiple transcripts, though encoding the same or similar protein products, can be highly informative and may account for subtle changes not detected at the protein level.

Varying responses of human cells with discrepant p53 activity to ionizing radiation and heat shock exposure

OBJECTIVES

Both heat shock (HS) and ionizing radiation have an impact on the cell cycle and may induce cell cycle arrest or apoptosis. Mutations of the p53 gene are observed at a high frequency in human tumours and are recognized in about half of all human cancers. Sensitivity to radiation, heat and anticancer agents has been observed in p53(+/+) cells, but not in mutated or p53-deficient cells. Moreover, enhancement of radiosensitivity by HS has been observed in wild-type p53 cells but not in p53-deficient cells. The molecular mechanism of the differential cell response to HS or ionizing radiation is not yet understood.

MATERIALS AND METHODS

Differences in cellular response to radiation (200 kV X-ray, 1, 2, 5 Gy) and HS (39 degrees C, 41 degrees C and 43 degrees C for 30 min) on cell cycle progression of cultures of human p53 mutant cells were investigated by flow cytometry. In addition, the effects of stressors used on the expression of several heat shock genes (HSP27, HSP60, HSP70, HSC70, HSP75, HSP78, HSP90) were studied by reverse transcriptase-polymerase chain reaction.

RESULTS AND CONCLUSIONS

Yet, with respect to HSP gene expression, different stressors produced similar effects. Combination of HS and radiation treatment significantly induced the transcription of the HSP70 gene above the level induced by each stressor alone. Cell cycle analysis, however, revealed striking differences in prolonged dynamics of cell division in response to each stressor. Thus, p53 status could be a useful indicator in predictive assays for hyperthermia cancer treatment in combination with radiation and/or chemotherapy.

Therapy through chaperones: sense or antisense? Cystic fibrosis as a model disease

Massive production and accumulation of a single abnormal protein may constitute a major toxic burden for the cell and even compromise the organism's long-term viability. Consequently, adaptation and survival have forced evolution to create 'quality control' mechanisms that detect, monitor, and often degrade such abnormally folded gene products, in which molecular chaperones are key players. Notwithstanding this, there are numerous examples of misfolded proteins which, in spite of being recognized as aberrant and efficiently discarded by cellular quality control, still retain some of the functional properties of their wild-type counterparts, so that their maintenance in the cell would be beneficial for the organism. Herein are described the cellular roles of molecular chaperones and some new insights on the mechanisms by which they influence the development of human diseases caused by mutations that lead to protein misfolding. A special emphasis is given to cystic fibrosis, a classical genetic disorder resulting from the retention and degradation of a mutant, albeit functional, protein by the endoplasmic reticulum quality control. This particular system has been a good example to describe the mechanisms that are likely to be shared by a number of protein substrates, to define the common characteristics of the mutants, as well as to identify the mechanistic intervenients in their retention and degradation. Finally, new approaches aimed at correcting protein folding defects are discussed, including the potential of molecular chaperones (e.g., through RNA interference) as novel therapeutic targets, and the usage of chemical or pharmacological chaperones as new therapeutic agents.

Transactivation of hsp70-1/2 in geldanamycin-treated human non-small cell lung cancer H460 cells: involvement of intracellular calcium and protein kinase C

Geldanamycin is an antitumor drug that binds HSP90 and induces a wide range of heat shock proteins, including HSP70s. In this study we report that the induction of HSP70s is dose-dependent in geldanamycin-treated human non-small cell lung cancer H460 cells. Analysis of the induction of HSP70s specific isoform using LC-ESI-MS/MS analysis and Northern blotting showed that HSP70-1/2 are the major inducible forms under geldanamycin treatment. Transactivation of hsp70-1/2 was determined by electrophoretic mobility-shift assay using heat shock element (HSE) as a probe. The signaling pathway mediators involved in hsp70-1/2 transactivation were screened by the kinase inhibitor scanning technique. Pretreatment with serine/threonine protein kinase inhibitors H7 or H8 blocked geldanamycin-induced HSP70-1/2, whereas protein kinase A inhibitor HA1004, protein kinase G inhibitor KT5823, and myosin light chain kinase inhibitor ML-7 had no effect. Furthermore, the protein kinase C (PKC)-specific inhibitor Ro-31-8425 and the Ca2+-dependent PKC inhibitor Gö-6976 diminished geldanamycin-induced HSP70-1/2, suggesting an involvement of the PKC in the process. In addition, geldanamycin treatment causes a transient increase of intracellular Ca2+. Chelating intracellular Ca2+ with BAPTA-AM or depletion of intracellular Ca2+ store with A23187 or thapsigargin significantly decreased geldanamycin-transactivated HSP70-1/2 expression. Taken together, our results demonstrate that geldanamycin-induced specific HSP70-1/2 isoforms expression in H460 cells through signaling pathway mediated by Ca2+ and PKC.

2.45 GHz radiofrequency fields alter gene expression in cultured human cells

The biological effect of radiofrequency (RF) fields remains controversial. We address this issue by examining whether RF fields can cause changes in gene expression. We used the pulsed RF fields at a frequency of 2.45 GHz that is commonly used in telecommunication to expose cultured human HL-60 cells. We used the serial analysis of gene expression (SAGE) method to measure the RF effect on gene expression at the genome level. We observed that 221 genes altered their expression after a 2-h exposure. The number of affected genes increased to 759 after a 6-h exposure. Functional classification of the affected genes reveals that apoptosis-related genes were among the upregulated ones and the cell cycle genes among the downregulated ones. We observed no significant increase in the expression of heat shock genes. These results indicate that the RF fields at 2.45 GHz can alter gene expression in cultured human cells through non-thermal mechanism.

A key role for stress-induced satellite III transcripts in the relocalization of splicing factors into nuclear stress granules

Exposure of cells to stressful conditions results in the rapid synthesis of a subset of specialized proteins termed heat shock proteins (HSPs) which function in protecting the cell against damage. The stress-induced activation of hsp genes is controlled by the heat shock transcription factor 1 (HSF1). At the cellular level, one of the most striking effects of stress is the rapid and reversible redistribution of HSF1 into a few nuclear structures termed nuclear stress granules which form primarily on the 9q12 locus in humans. Within these structures, HSF1 binds to satellite III repeated elements and drives the RNA polymerase II-dependent transcription of these sequences into stable RNAs which remain associated with the 9q12 locus for a certain time after synthesis. Other proteins, in particular splicing factors, were also shown to relocalize to the granules upon stress. Here, we investigated the role of stress-induced satellite III transcripts in the relocalization of splicing factors to the granules. We show that the recruitment of the two serine/arginine-rich (SR) proteins SF2/ASF and SRp30c requires the presence of stress-induced satellite III transcripts. In agreement with these findings, we identified the second RNA-recognition motif (RRM2) of hSF2/ASF as the motif required for the targeting to the granules, and we showed by immunoprecipitation that the endogenous hSF2/ASF protein is present in a complex with satellite III transcripts in stressed cells in vivo. Interestingly, satellite III transcripts also immunoprecipitate together with small nuclear ribonucleoproteins (snRNPs) in vivo whereas the intronless hsp70 transcripts do not, supporting the proposal that these transcripts are subject to splicing. Altogether, these data highlight the central role for satellite III transcripts in the targeting and/or retention of splicing factors into the granules upon stress.

Heat-shock response is associated with decreased production of interleukin-6 in murine aortic vascular smooth muscle cells

Heat shock has been known to change cellular responses to noxious stimuli by inducing heat-shock proteins (Hsps). We hypothesized that a heat-shock response modulates cytokine production in murine aortic vascular smooth muscle cells (VSMCs). VSMCs were exposed to 44 degrees C for 15-60 min, and subjected to interleukin-1beta (IL-1beta) or tumor necrosis factor alpha (TNFalpha), which induced interleukin-6 (IL-6) production. Expression of Hsps was examined with immunoblots, immunocytochemistry, or enzyme-linked immunosorbent assay (ELISA), and that of IL-6 with reverse transcription-polymerase chain reaction (RT-PCR) or ELISA. Heat shock (44 degrees C for 45 min) induced Hsp72 in VSMCs at 4 h and elicited its maximal expression at 8 h after the end of heat shock. Treatment with IL-1beta increased IL-6 transcription in VSMCs up to 24 h in an incubation time-dependent manner. Treatment with IL-1beta or TNFalpha caused a concentration-dependent increase in IL-6 production in culture medium, which was attenuated by heat shock. Although treatment with Hsp72 or Hsp60 alone did not significantly affect basal IL-6 release into culture medium statistically, cotreatment with IL-1beta and Hsp72, but not Hsp60 or boiled Hsp72, decreased IL-1beta-induced IL-6 production in culture medium. Introduction of Hsp72, but not Hsp60, into VSMCs decreased IL-1beta-induced IL-6 production in culture medium. These results indicate that the heat-shock response transcriptionally attenuated production of IL-6 in murine aortic VSMCs.

Hsp70 release from peripheral blood mononuclear cells

There are an increasing number of studies reporting the presence of Hsps in human serum. We have investigated the release of Hsp70 into blood and culture medium from peripheral blood mononuclear cells (PBMCs), and whether this release is due to cell damage or active secretion from the cells. Intact Hsp70 was released from cells within whole blood and from purified PBMCs under normal culture conditions. Hsp70 release was rapid (0.1 ng/10(6) cells/h) over the first 2 h of culture and continued at a reduced rate up to 24 h (<0.025 ng/10(6) cells/h). Using viable cell counts and lactate dehydrogenase release we were able to confirm that the release of Hsp70 was not due to cellular damage. Hsp70 release was inhibited by monensin, methyl-beta-cyclodextrin, and methylamine, but not by brefeldin A. These data suggest that Hsp70 is released from cells via a non-classical pathway, possibly involving lysosomal lipid rafts.

BRIEF EXPOSURE TO ETHANOL AUGMENTS VASCULAR CONTRACTILITY IN HUMAN CHORIONIC PLATE ARTERIES

Heavy alcohol consumption has been known as a risk factor for hypertension, although the mechanism by which alcohol intake causes hypertension remains elusive. We tested the hypothesis that brief exposure to ethanol augments vascular contractility through the stress response in human chorionic plate arteries. Human chorionic plate arteries were mounted in organ baths and exposed to 5% ethanol for 15, 30 or 45 min. Brief exposure for 45 min, but not 15 min, not only augmented contractility to KCl and 5-hydroxytryptamine 5 h after the end of exposure, but also increased the expression of heat shock protein (HSP) 70 in the tissues. Reverse transcription-polymerase chain reaction showed gradual increases of hsp70 mRNA expression, but not heat shock cognate 70 (hsc70), hsp90alpha or glucose regulatory protein 78 (grp78) mRNA expression, in an exposure time-dependent manner 3 h after the end of exposure. These results indicate that ethanol augments vascular contractility through the stress response.

Weak electromagnetic fields (50 Hz) elicit a stress response in human cells

The aim of this study was to demonstrate the expression of heat shock (HS) genes in human cells in response to extremely low-frequency electromagnetic fields (ELF-EMF) alone and in combination with thermal stress. After exposing human myeloid leukemia (HL-60) cells to the stressor(s) for 30 min we quantified the expression of the HS genes HSP27, HSP60, HSP70 (A, B, and C), HSC70, HSP75, HSP78, and HSP90 (alpha and beta) by RT-PCR. The results clearly show that HS genes, in particular the three HSP70 genes (A, B, and C), are induced by ELF-EMF, a reaction that is enhanced by simultaneous HS (43 degrees C for 30 min). The results show similarities and some significant differences to previous experiments in which transgenic nematodes were used to monitor the induction of the HSP70 gene under similar stress conditions. We also studied the effect of different flux densities on gene expression in the range of 10-140 microT. Even the lowest dose tested (10 microT) resulted in a significant induction of the genes HSP70A, HSP70B, and HSP70C. The reaction to ELF-EMF shows a maximum at a flux density of 60-80 microT. The unusual dose-response relation reveals an interesting difference to other stressors that elicit the HS response.

Stress-induced transcription of satellite III repeats

Exposure of mammalian cells to stress induces the activation of heat shock transcription factor 1 (HSF1) and the subsequent transcription of heat shock genes. Activation of the heat shock response also correlates with a rapid relocalization of HSF1 within a few nuclear structures termed nuclear stress granules. These stress-induced structures, which form primarily on the 9q12 region in humans through direct binding of HSF1 to satellite III repeats, do not colocalize with transcription sites of known hsp genes. In this paper, we show that nuclear stress granules correspond to RNA polymerase II transcription factories where satellite III repeats are transcribed into large and stable RNAs that remain associated with the 9q12 region, even throughout mitosis. This work not only reveals the existence of a new major heat-induced transcript in human cells that may play a role in chromatin structure, but also provides evidence for a transcriptional activity within a locus considered so far as heterochromatic and silent.

PTHrP [67-86] regulates the expression of stress proteins in breast cancer cells inducing modifications in urokinase-plasminogen activator and MMP-1 expression

It was previously reported that a midregion domain of parathyroid hormone-related protein (PTHrP), that is, [67-86]-amide, is able to restrain growth and promote matrigel penetration by the 8701-BC cell line, derived from a biopsy fragment of a primary ductal infiltrating carcinoma of the human breast, and that cell invasion in vitro is drastically impaired by inactivation of urokinase-plasminogen activator (uPa). In this study we started a more detailed investigation of the possible effects on gene expression arising from the interaction between PTHrP [67-86]-amide and 8701-BC breast cancer cells by a combination of conventional-, differential display-and semi-quantitative multiplex-polymerase chain reaction (PCR) assays. We present here the first evidence that the upregulation of some stress-related genes, most noticeably heat shock factor binding protein-1 (hsbp1) and heat shock protein 90 (hsp-90), is involved in the acquisition of an in vitro more invasive phenotype by cells treated with midregion PTHrP. This is conceivably accomplished by sequestering and inactivating heat shock factor-1 (hsf1) which is able to recognize Ets transcription-factor-binding sites present in some gene promoters, such as those of uPa and matrix metalloprotease-1 (MMP-1). In fact, our data show that incubation of PTHrP [67-86]-amide-treated cells with either antisense hsbp1-oligonucleotide or geldanamycin, an hsp90-inactivating antibiotic, results in downregulation of uPa and upregulation of MMP-1, and in a prominent inhibition of cell invasion in matrigel-containing Transwell chambers. Alternatively, incubation of untreated 8701-BC cells with quercetin, a flavonoid known to decrease the amount of free hsf1, is found to induce upregulation of uPa and downregulation of MMP-1, and an increase of matrigel invasion by cells, thus providing further supporting data of the involvement of hsf unavailability on the modulation of uPa and MMP-1 expression and on cell invasive behaviour. These studies confirm a previous postulate that over-secretion of uPa, rather than of other extracellular proteases, is a primary condition for the increase of invasive activity triggered by PTHrP [67-86]-amide in vitro, and support a role for midregion forms of PTHrP in potentially affecting pathological mammary growth and differentiation. They also identify two new key protagonists in the complex scenario of breast tumor cell invasiveness in vitro, that is, hsbp1 and hsp90, which deserve further and more extensive studies as potential and attractive molecular targets for anti-breast cancer treatments.

Development of cross-resistance between heat and cisplatin or hydroxyurea treatments in FaDu squamous carcinoma cells

BACKGROUND

Induction of hyperthermia by radiofrequency ablation is gaining popularity in treating a variety of solid tumors. This study examined an impact of sublethal heat treatment interacted with chemotherapeutic drugs on the survival of head and neck squamous carcinoma cells using in vitro model.

MATERIALS AND METHODS

FaDu cells were subjected to heat treatment at 42 degrees C or 45 degrees C for 15 min either before or after exposure to cisplatin or hydroxyurea. The survival of cells was determined by 3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide assay. The RNA and protein levels of various heat shock proteins were examined by reverse transcription polymerase chain reaction and Western blot analysis, respectively. Cell cycle progression was analyzed by flow cytometry with propidium iodide staining.

RESULTS

FaDu cells preheated to 45 degrees C exhibited an increased resistance to hydroxyurea but not to cisplatin. The heat treatment resulted in induction of HSP70 expression at transcript and protein levels, but there was no change in expression of HSP90beta and HSP27. After heat treatment, cells accumulated in S-phase at 3 h and proceeded to G(2)/M phase at 24 h. When cells pre-exposed to drugs for 24 h, the cisplatin-treated cells exhibited a higher thermotolerance than the hydroxyurea-treated cells at heat treatment of 45 degrees C. Cisplatin and hydroxyurea caused cells to accumulate in S-phase and increased the protein expression of HSP27 but not HSP90beta and HSP70.

CONCLUSION

FaDu cells surviving the heat treatment expressed HSP70 and disrupted cell cycle progression, which resulted in developing a resistance to subsequent hydroxyurea treatment. However, the heat treatment did not have an effect on the sensitivity to cisplatin. In the reversed procedure, pre-exposure to hydroxyurea and cisplatin resulted in developing a thermotolerance.

Hspa4 (HSP70) is involved in the radioadaptive response: results from mouse splenocytes

In a continuation of our earlier study on the involvement of HSP25 (now known as Hspb1) and HSP70 (now known as Hspa4) in the induction of an adaptive response, we examined the involvement of these proteins in the induction of the adaptive response using an animal model system. C57BL6 mice were irradiated with 5 cGy of gamma radiation three times in 1 week (for a total of 15 cGy), and a high challenge dose (6 Gy) was given on the day after the last low-dose irradiation. The survival time of the low-dose preirradiated mice was increased to 30%. The induction of apoptosis induced by 6 Gy was also reduced by this low-dose preirradiation regimen. To elucidate any link existing between the HSPs and the induction of the adaptive response, reverse transcriptase (RT)-polymerase chain reaction (PCR) analysis was performed using splenocytes. High-dose radiation up-regulated the expression of Hspb1 and especially Hspa4, while expression of other HSPs such as HSC70 (now know as Hspa8), Hsp90, and alphaB-crystalline (now known as Cryab) did not change. When splenocytes from Hspa4 transgenic mice were preirradiated with a low dose of radiation, a reduction in cell death after high-dose irradiation was observed. These results suggest that Hspa4 is a key molecule in the induction of the adaptive response.

Induction of adaptive response by low-dose radiation in RIF cells transfected with Hspb1 (Hsp25) or inducible Hspa (Hsp70)

An adaptive response results in a reduced effect of a high challenging dose of a stressor after a smaller, inducing dose has been applied a few hours earlier. Radiation-induced fibrosarcoma (RIF) cells did not show an adaptive response, i.e. a reduced effect from a high challenging dose (2 Gy) of a radiation after a priming dose (1 cGy) had been applied 4 or 7 h earlier, but cells of a thermoresistant clone (TR) derived from RIF cells did. Since the expression of inducible Hspa (also known as Hsp70) and Hspb1 (also known as Hsp25) was different in these two cell lines, the role of inducible Hspa and Hspb1 in the adaptive response was examined. When RIF cells were transfected with inducible Hspa or Hspb1, both radioresistance measured by clonogenic assays and a reduction of apoptosis were detected. The adaptive response was also acquired by these two cell lines. The inducible Hspa transfectant showed a more pronounced adaptive response than the Hspb1 transfectant. Based on these results, it appears that inducible Hspa and Hspb1 are at least partly responsible for the induction of the adaptive response in these cells. Moreover, when inducible Hspa or Hspb1 was transfected into RIF cells, co-regulation of the two genes was detected. Heat-shock factor (Hsf) was found to be at least partially responsible for the induction of the adaptive response in these cells.

Comprehensive expression profile analysis of the Arabidopsis Hsp70 gene family

We isolated cDNA clones for two nuclear-encoded, organellar members of the Arabidopsis hsp70 gene family, mtHsc70-2 (AF217458) and cpHsc70-2 (AF217459). Together with the completion of the genome sequence, the hsp70 family in Arabidopsis consists of 14 members unequally distributed among the five chromosomes. To establish detailed expression data of this gene family, a comprehensive reverse transcriptase-polymerase chain reaction analysis for 11 hsp70s was conducted including analysis of organ-specific and developmental expression and expression in response to temperature extremes. All hsp70s showed 2- to 20-fold induction by heat shock treatment except cpHsc70-1 and mtHsc70-1, which were unchanged or repressed. The expression profiles in response to low temperature treatment were more diverse than those evoked by heat shock treatment. Both mitochondrial and all cytosolic members of the family except Hsp70b were strongly induced by low temperature, whereas endoplasmic reticulum and chloroplast members were not induced or were slightly repressed. Developmentally regulated expression of the heat-inducible Hsp70 in mature dry seed and roots in the absence of temperature stress suggests prominent roles in seed maturation and root growth for this member of the hsp70 family. This reverse transcriptase-polymerase chain reaction analysis establishes the complex differential expression pattern for the hsp70s in Arabidopsis that portends specialized functions even among members localized to the same subcellular compartment.

Intron-independent association of splicing factors with active genes

The cell nucleus is organized as discrete domains, often associated with specific events involved in chromosome organization, replication, and gene expression. We have examined the spatial and functional relationship between the sites of heat shock gene transcription and the speckles enriched in splicing factors in primary human fibroblasts by combining immunofluorescence and fluorescence in situ hybridization (FISH). The hsp90alpha and hsp70 genes are inducibly regulated by exposure to stress from a low basal level to a high rate of transcription; additionally the hsp90alpha gene contains 10 introns whereas the hsp70 gene is intronless. At 37 degrees C, only 30% of hsp90alpha transcription sites are associated with speckles whereas little association is detected with the hsp70 gene, whose constitutive expression is undetectable relative to the hsp90alpha gene. Upon exposure of cells to heat shock, the heavy metal cadmium, or the amino acid analogue azetidine, transcription at the hsp90alpha and hsp70 gene loci is strongly induced, and both hsp transcription sites become associated with speckles in >90% of the cells. These results reveal a clear disconnection between the presence of intervening sequences at specific gene loci and the association with splicing factor-rich regions and suggest that subnuclear structures containing splicing factors are associated with sites of transcription.