PTEN-induced kinase 1 gene single-nucleotide variants as biomarkers in adjuvant chemotherapy for colorectal cancer: a retrospective study.

BACKGROUND: Fluoropyrimidine-based postoperative adjuvant chemotherapy is globally recommended for high-risk stage II and stage III colon cancer. However, adjuvant chemotherapy is often associated with severe adverse events and is not highly effective in preventing recurrence. Therefore, discovery of novel molecular biomarkers of postoperative adjuvant chemotherapy to identify patients at increased risk of recurrent colorectal cancer is warranted. Autophagy (including mitophagy) is activated under chemotherapy-induced stress and contributes to chemotherapy resistance. Expression of autophagy-related genes and their single-nucleotide polymorphisms are reported to be effective predictors of chemotherapy response in some cancers. Our goal was to evaluate the relationship between single-nucleotide variants of autophagy-related genes and recurrence rates in order to identify novel biomarkers that predict the effect of adjuvant chemotherapy in colorectal cancer. METHODS: We analyzed surgical or biopsy specimens from 84 patients who underwent radical surgery followed by fluoropyrimidine-based adjuvant chemotherapy at Saitama Medical University International Medical Center between January and December 2016. Using targeted enrichment sequencing, we identified single-nucleotide variants and insertions/deletions in 50 genes, including autophagy-related genes, and examined their association with colorectal cancer recurrence rates. RESULTS: We detected 560 single-nucleotide variants and insertions/deletions in the target region. The results of Fisher's exact test indicated that the recurrence rate of colorectal cancer after adjuvant chemotherapy was significantly lower in patients with the single-nucleotide variants (c.1018G > A [p < 0.005] or c.1562A > C [p < 0.01]) of the mitophagy-related gene PTEN-induced kinase 1. CONCLUSIONS: The two single-nucleotide variants of PINK1 gene may be biomarkers of non-recurrence in colorectal cancer patients who received postoperative adjuvant chemotherapy.

Progressive metastatic pheochromocytoma induced by multiple endocrine neoplasia type 2A with a lethal outcome.

Introduction: Patients with multiple endocrine neoplasia type 2A (MEN2A) harboring a pathological variant in the RET gene are characterized by medullary thyroid carcinoma (MTC), pheochromocytoma, and hyperparathyroidism. Although pheochromocytoma is currently defined as a malignant tumor, MEN2A-associated pheochromocytoma is known to have a small risk of metastasis. Case presentation: The case was a 62-year-old Japanese male with bilateral pheochromocytoma, multiple metastases in the liver and bones, and a cardiac thrombus. Genetic testing revealed a pathological variant at codon 634 of the RET gene, thereby leading a diagnosis of MTC. We considered that the multiple metastases were due to MTC; however, a liver biopsy revealed metastasis of pheochromocytoma. Conclusion: When pheochromocytoma precedes MTC, the diagnosis of MEN2A may be difficult.

Interval between the First Cancer and the Genetic Diagnosis in Lynch Syndrome Probands.

Objective Little is known about the time from developing a first cancer to confirming the presence of a mismatch repair (MMR) gene mutation for Lynch syndrome (LS) probands. Methods This was a retrospective single center study. LS probands, who have an MMR gene mutation that was confirmed first in a pedigree and thereafter developed at least one cancer, were included in this study. Results There were 21 LS probands who had developed at least one cancer; 6 with MLH1 mutations, 9 with MSH2 mutations, 4 with MSH6 mutations, and 2 with EPCAM deletions. The median ages at the first cancer and the genetic diagnosis were 47 (34-71) and 62 (38-84) years old, respectively. The mean interval between the first cancer and the genetic diagnosis was 11.0 (0-25) years, and 20 years or longer interval was required for the 5 probands. Six (28.6%) probands were older than 70 years, and 3 (14.3%) were in their 80s when they were diagnosed to have LS. The genetic diagnosis was confirmed at the first, second, third, and fourth cancer or later in 5, 5, 6, and 5 probands, respectively. Of the 16 cancers examined, 2 (12.5%) were microsatellite stable (MSS), both of whom had germline MSH6 mutations. All 17 LS probands who developed colorectal cancer met the revised Bethesda guidelines at the genetic diagnosis, but only 7 of 11 (63.6%) met them at the first cancer. Twelve out of 21 (57.1%) met the revised Amsterdam criteria. Conclusion It took 11 years for the LS probands from the first cancer to the diagnostic confirmation by genetic tests. A quarter of the probands were in their 70s or 80s at genetic diagnosis.

Profiling cancer-related gene mutations in oral squamous cell carcinoma from Japanese patients by targeted amplicon sequencing.

Somatic mutation analysis is a standard practice in the study of human cancers to identify mutations that cause therapeutic sensitization and resistance. We performed comprehensive genomic analyses that used PCR target enrichment and next-generation sequencing on Ion Proton semiconductor sequencers. Forty-seven oral squamous cell carcinoma (OSCC) samples and their corresponding noncancerous tissues were used for multiplex PCR amplification to obtain targeted coverage of the entire coding regions of 409 cancer-related genes (covered regions: 95.4% of total, 1.69 megabases of target sequence). The number of somatic mutations in 47 patients with OSCC ranged from 1 to 20 with a mean of 7.60. The most frequent mutations were in TP53 (61.7%), NOTCH1 (25.5%), CDKN2A (19.1%), SYNE1 (14.9%), PIK3CA (10.6%), ROS1 (10.6%), and TAF1L (10.6%). We also detected copy number variations (CNVs) in the segments of the genome that could be duplicated or deleted from deep sequencing data. Pathway assessment showed that the somatic aberrations within OSCC genomes are mainly involved in several important pathways, including cell cycle regulation and RTK-MAPK-PI3K. This study may enable better selection of therapies and deliver improved outcomes for OSCC patients when combined with clinical diagnostics.

Multidrug resistance-associated protein 4 is a determinant of arsenite resistance.

Although arsenic trioxide (arsenite, As(III)) has shown a remarkable efficacy in the treatment of acute promyelocytic leukemia patients, multidrug resistance is still a major concern for its clinical use. Multidrug resistance-associated protein 4 (MRP4), which belongs to the ATP-binding cassette (ABC) superfamily of transporters, is localized to the basolateral membrane of hepatocytes and the apical membrane of renal proximal tubule cells. Due to its characteristic localization, MRP4 is proposed as a candidate in the elimination of arsenic and may contribute to resistance to As(III). To test this hypothesis, stable HEK293 cells overexpressing MRP4 or MRP2 were used to establish the role of these two transporters in As(III) resistance. The IC50 values of As(III) in MRP4 cells were approximately 6-fold higher than those in MRP2 cells, supporting an important role for MRP4 in resistance to As(III). The capacity of MRP4 to confer resistance to As(III) was further confirmed by a dramatic decrease in the IC50 values with the addition of MK571, an MRP4 inhibitor, and cyclosporine A, a well-known broad-spectrum inhibitor of ABC transporters. Surprisingly, the sensitivity of the MRP2 cells to As(III) was similar to that of the parent cells, although insufficient formation of glutathione and/or Se conjugated arsenic compounds in the MRP2 cells might limit transport. Given that MRP4 is a major contributor to arsenic resistance in vitro, further investigation into the correlation between MRP4 expression and treatment outcome of leukemia patients treated with arsenic-based regimens is warranted.

Insolubilization of cadmium in paddy field using atomized iron powder and extracting reagent.

The insolubilization of cadmium in the soil of a naturally cadmium-contaminated paddy field was studied using an atomized iron powder and an extracting reagent. Cadmium in the soil was extracted into the water phase by calcium chloride. The extracted cadmium was deposited on the iron powder. The deposition of cadmium was significantly influenced by calcium chloride, since the surface area of the iron powder increased with the increasing calcium chloride concentration. We discuss the potential of the technique and the insolubilization mechanism.

OATP1B1-related drug-drug and drug-gene interactions as potential risk factors for cerivastatin-induced rhabdomyolysis.

OBJECTIVE: Genetic variation in drug metabolizing enzymes and membrane transporters as well as concomitant drug therapy can modulate the beneficial and the deleterious effects of drugs. We investigated whether patients exhibiting rhabdomyolysis who were taking cerivastatin possess functional genetic variants in SLCO1B1 and whether they were on concomitant medications that inhibit OATP1B1, resulting in accumulation of cerivastatin. METHODS: This study had three components: (a) resequencing the SLCO1B1 gene in 122 patients who developed rhabdomyolysis while on cerivastatin; (b) functional evaluation of the identified SLCO1B1 nonsynonymous variants and haplotypes in in-vitro HEK293/FRT cells stably transfected with pcDNA5/FRT empty vector, SLCO1B1 reference, variants, and haplotypes; and (c) in-vitro screening of 15 drugs commonly used among the rhabdomyolysis cases for inhibition of OATP1B1-mediated uptake of cerivastatin in HEK293/FRT cells stably transfected with reference SLCO1B1. RESULTS: The resequencing of the SLCO1B1 gene identified 54 variants. In-vitro functional analysis of SLCO1B1 nonsynonymous variants and haplotypes showed that the V174A, R57Q, and P155T variants, a novel frameshift insertion, OATP1B1*14 and OATP1B1*15 haplotype were associated with a significant reduction (P<0.001) in cerivastatin uptake (32, 18, 72, 3.4, 2.1 and 5.7% of reference, respectively). Furthermore, clopidogrel and seven other drugs were shown to inhibit OATP1B1-mediated uptake of cerivastatin. CONCLUSION: Reduced function of OATP1B1 related to genetic variation and drug-drug interactions likely contributed to cerivastatin-induced rhabdomyolysis. Although cerivastatin is no longer in clinical use, these findings may translate to related statins and other substrates of OATP1B1.

Attenuation of cisplatin-induced renal injury by inhibition of soluble epoxide hydrolase involves nuclear factor κB signaling.

Acute kidney injury is associated with a significant inflammatory response that has been the target of renoprotection strategies. Epoxyeicosatrienoic acids (EETs) are anti-inflammatory cytochrome P450-derived eicosanoids that are abundantly produced in the kidney and metabolized by soluble epoxide hydrolase (sEH; Ephx2) to less active dihydroxyeicosatrienoic acids. Genetic disruption of Ephx2 and chemical inhibition of sEH were used to test whether the anti-inflammatory effects of EETs, and other lipid epoxide substrates of sEH, afford protection against cisplatin-induced nephrotoxicity. EET hydrolysis was significantly reduced in Ephx2(-/-) mice and was associated with an attenuation of cisplatin-induced increases in serum urea nitrogen and creatinine levels. Histological evidence of renal tubular damage and neutrophil infiltration was also reduced in the Ephx2(-/-) mice. Likewise, cisplatin had no effect on renal function, neutrophil infiltration, or tubular structure and integrity in mice treated with the potent sEH inhibitor 1-adamantan-1-yl-3-(1-methylsulfonyl-piperidin-4-yl-urea) (AR9273). Consistent with the ability of EETs to interfere with nuclear factor-κB (NF-κB) signaling, the observed renoprotection was associated with attenuation of renal NF-κB activity and corresponding decreases in the expression of tumor necrosis factor (TNF) α, TNF receptor (TNFR) 1, TNFR2, and intercellular adhesive molecule-1 before the detection of tubular injury. These data suggest that EETs or other fatty acid epoxides can attenuate cisplatin-induced kidney injury and sEH inhibition is a novel renoprotective strategy.

Azithromycin suppresses proliferation, interleukin production and mitogen-activated protein kinases in human peripheral-blood mononuclear cells stimulated with bacterial superantigen.

OBJECTIVES: Macrolide antibiotics are used for the treatment of immunological disorders such as psoriasis. However, few studies have investigated the immunoregulatory efficacy of macrolides in bacterial superantigen-stimulated immune cells. METHODS: The suppressive efficacies of azithromycin, clarithromycin, roxithromycin and prednisolone were evaluated in vitro against the concanavalin A- or toxic shock syndrome toxin 1 (TSST-1)-induced proliferation of peripheral-blood mononuclear cells (PBMCs) obtained from nine healthy subjects. The concentrations of six cytokines in a PBMC-culture medium were measured using bead-array procedures followed by flow cytometry. Cellular c-jun N-terminal kinase (JNK) and extracellular signal-regulated kinase (ERK) activity were measured using cell-based ELISA procedures. KEY FINDINGS: Azithromycin, clarithromycin and roxithromycin inhibited the proliferation of both the concanavalin A- and superantigen-stimulated PBMCs dose-dependently. The effect of azithromycin was the strongest, with IC50 values of less than 5 µg/ml. Furthermore, the suppressive efficacy of prednisolone against concanavalin A- or TSST-1-stimulated PBMCs was significantly promoted in combination with 5 µg/ml azithromycin (P < 0.002). The concentrations of TNF-α, interleukin (IL)-2, -4, -5 and -10 in the supernatant of concanavalin A- or TSST-1-stimulated PBMCs cultured for 72 h decreased by 65-98% in the presence of 5 µg/ml azithromycin. The stimulation of PBMCs with concanavalin A or TSST-1 increased cellular JNK and ERK activity, and 5 µg/ml azithromycin significantly attenuated the increased activity of JNK in the TSST-1-stimulated cells and ERK in the concanavalin A- and TSST-1-stimulated PBMCs, respectively (P < 0.05). CONCLUSIONS: Azithromycin suppresses mitogen- or superantigen-induced proliferation of PBMCs by possibly inhibiting both cellular JNK and ERK activity.

Cerivastatin, genetic variants, and the risk of rhabdomyolysis.

OBJECTIVE: The withdrawal of cerivastatin involved an uncommon but serious adverse reaction, rhabdomyolysis. The bimodal response, rhabdomyolysis in a small proportion of users, points to genetic factors as a potential cause. We conducted a case-control study to evaluate genetic markers for cerivastatin-associated rhabdomyolysis. METHODS: This study had two components: a candidate gene study to evaluate variants in CYP2C8, UGT1A1, UGT1A3, and SLCO1B1; and a genome-wide association study to identify risk factors in other regions of the genome. A total of 185 rhabdomyolysis cases were frequency matched to statin-using controls from the Cardiovascular Health Study (n=374) and the Heart and Vascular Health Study (n=358). Validation relied on functional studies. RESULTS: Permutation test results suggested an association between cerivastatin-associated rhabdomyolysis and variants in SLCO1B1 (P=0.002), but not variants in CYP2C8 (P=0.073) or UGTs (P=0.523). An additional copy of the minor allele of SLCO1B1 rs4149056 (p.Val174Ala) was associated with the risk of rhabdomyolysis (odds ratio: 1.89; 95% confidence interval: 1.40-2.56). In transfected cells, this variant reduced cerivastatin transport by 40% compared with the reference transporter (P<0.001). The genome-wide association study identified an intronic variant (rs2819742) in the ryanodine receptor 2 gene (RYR2) as significant (P=1.74E-07). An additional copy of the minor allele of the RYR2 variant was associated with a reduced risk of rhabdomyolysis (odds ratio: 0.48; 95% confidence interval: 0.36-0.63). CONCLUSION: We identified modest genetic risk factors for an extreme response to cerivastatin. Disabling genetic variants in the candidate genes were not responsible for the bimodal response to cerivastatin.

A novel method for ABO genotyping using a DNA chip.

ABO genotyping is often performed to identify the blood type of decomposed samples, which is difficult to be determined by a serological test. In this study, we developed a simple method for ABO genotyping using a DNA chip. In this method, polymerase chain reaction-amplified and fluorescent-labeled fragments in the ABO gene and primate-specific D17Z1 were hybridized with DNA probes on a chip designed to detect single nucleotide polymorphisms (SNPs) in the ABO gene and part of the D17Z1 sequence. Using blood samples from 42 volunteers and 10 animal species, we investigated whether the chip could be used to detect SNPs in the ABO gene and the D17Z1 sequence. This method was then applied to various forensic samples, and it was confirmed that this method was suitable for the simultaneous analyses of ABO genotyping and species identification. This method fulfills the recent need for the development of rapid and convenient methods for criminal investigations.

Functional hot spots in human ATP-binding cassette transporter nucleotide binding domains.

The human ATP-binding cassette (ABC) transporter superfamily consists of 48 integral membrane proteins that couple the action of ATP binding and hydrolysis to the transport of diverse substrates across cellular membranes. Defects in 18 transporters have been implicated in human disease. In hundreds of cases, disease phenotypes and defects in function can be traced to nonsynonymous single nucleotide polymorphisms (nsSNPs). The functional impact of the majority of ABC transporter nsSNPs has yet to be experimentally characterized. Here, we combine experimental mutational studies with sequence and structural analysis to describe the impact of nsSNPs in human ABC transporters. First, the disease associations of 39 nsSNPs in 10 transporters were rationalized by identifying two conserved loops and a small α-helical region that may be involved in interdomain communication necessary for transport of substrates. Second, an approach to discriminate between disease-associated and neutral nsSNPs was developed and tailored to this superfamily. Finally, the functional impact of 40 unannotated nsSNPs in seven ABC transporters identified in 247 ethnically diverse individuals studied by the Pharmacogenetics of Membrane Transporters consortium was predicted. Three predictions were experimentally tested using human embryonic kidney epithelial (HEK) 293 cells stably transfected with the reference multidrug resistance transporter 4 and its variants to examine functional differences in transport of the antiviral drug, tenofovir. The experimental results confirmed two predictions. Our analysis provides a structural and evolutionary framework for rationalizing and predicting the functional effects of nsSNPs in this clinically important membrane transporter superfamily.

Evaluation of Tamm-Horsfall protein and uroplakin III for forensic identification of urine.

In this study, Tamm-Horsfall protein (THP), a major component of urinary protein, and uroplakin III (UPIII), a transmembrane protein widely regarded as a urothelium-specific marker, were evaluated for forensic identification of urine by ELISA and/or immunohistochemistry. THP was detected in urine, but not in plasma, saliva, semen, vaginal fluid, or sweat by the simple ELISA method developed in this study. In addition, most aged urine stains showed positive results. The urine specificity of THP was confirmed by gene expression analysis. Therefore, as reported previously, ELISA detection of THP can be used as a presumptive test for urine identification. UPIII was specific for immunohistochemical staining of cells in centrifuged precipitate of urine. However, ELISA and RT-PCR for UPIII were not specific for urine. UPIII may be applicable for forensic urine identification by immunohistochemistry.

Detection of dermcidin for sweat identification by real-time RT-PCR and ELISA.

We evaluated the performance of real-time RT-PCR and ELISA assays for detection of dermcidin (DCD) in sweat and body-fluid stains. DCD, a small antibiotic peptide secreted into human sweat, was detected by real-time RT-PCR in 7-day-old stains containing as small as 10 microL of sweat, and the assay showed high specificity when testing 7-day-old stains containing 30 microL of other body-fluid. ELISA using anti-human dermcidin mouse monoclonal antibody detected DCD sweat diluted up to approximately 10,000-fold and could specifically detect DCD in 10 microL of body-fluid stains. The performance of the two assays was tested during winter on samples that simulated forensic case samples: an undershirt and a sock worn for 20 h, a handkerchief used to wipe the brow several times within 12h, a cap and a cotton glove worn for 4h, and a white robe worn at intervals for 2 years. The result showed that the former assay detected DCD in all sites of the undershirt examined (armpit, back, and breast), and the latter gave a relatively high OD value in the armpit among the three sites. For the socks, although the latter assay gave very high OD values in both the center and toe of the foot sole, the former could not detect DCD in both of them. These results indicate that highly damp conditions, such as inside a shoe, might promote the degradation of mRNA in samples such as socks. In the other case samples, sweat was adequately detected by both assays. This study is the first demonstration of the use of real-time RT-PCR to sensitively identify sweat among body-fluid stains, and it confirmed that dermcidin was an excellent marker for sweat identification. In addition, the usefulness of ELISA was also verified. Positive sweat identification using these assays is expected to assist forensic practice.

Genetic variation in the proximal promoter of ABC and SLC superfamilies: liver and kidney specific expression and promoter activity predict variation.

Membrane transporters play crucial roles in the cellular uptake and efflux of an array of small molecules including nutrients, environmental toxins, and many clinically used drugs. We hypothesized that common genetic variation in the proximal promoter regions of transporter genes contribute to observed variation in drug response. A total of 579 polymorphisms were identified in the proximal promoters (-250 to +50 bp) and flanking 5' sequence of 107 transporters in the ATP Binding Cassette (ABC) and Solute Carrier (SLC) superfamilies in 272 DNA samples from ethnically diverse populations. Many transporter promoters contained multiple common polymorphisms. Using a sliding window analysis, we observed that, on average, nucleotide diversity (pi) was lowest at approximately 300 bp upstream of the transcription start site, suggesting that this region may harbor important functional elements. The proximal promoters of transporters that were highly expressed in the liver had greater nucleotide diversity than those that were highly expressed in the kidney consistent with greater negative selective pressure on the promoters of kidney transporters. Twenty-one promoters were evaluated for activity using reporter assays. Greater nucleotide diversity was observed in promoters with strong activity compared to promoters with weak activity, suggesting that weak promoters are under more negative selective pressure than promoters with high activity. Collectively, these results suggest that the proximal promoter region of membrane transporters is rich in variation and that variants in these regions may play a role in interindividual variation in drug disposition and response.

Effects of oximes on mitochondrial oxidase activity.

Oximes, including 2-pyridinealdoxime methiodide (2-PAM), are reactivators of acetylcholinesterase (AChE) inhibited by organophosphate poisoning. Unfortunately, their clinical use has been limited by their toxicity. To investigate the mechanism of this toxicity, the effects of oximes on the enzymes choline oxidase (ChOD) and cytochrome c oxidase (CyCOD) of the respiratory chain in mitochondria were examined. The oximes 2-PAM, obidoxime, and diacetylmonoxime significantly (P<0.01) inhibited ChOD activity, and the extent of inhibition correlated with the ability to reactivate inhibited AChE. When ChOD activity in mitochondrial extracts was tested, 2-PAM inhibited the activity by 75%, obidoxime and diacetylmonoxime did not significantly inhibit it, and 4-[(hydroxy-imino)methyl]-1-decylpyridinium bromide (4-PAD), which has greater toxicity, increased the amount of product generated in the assay to approximately 200% of normal levels. Similarly, 2-PAM inhibited the activity of CyCOD in mitochondrial extracts whereas obidoxime and diacetylmonoxime did not. One explanation for these findings is that, in addition to their inhibition of mitochondrial oxidases, the oximes may produce excessive reactive oxygen species such as H(2)O(2) in the mitochondrial fraction, which may account for some of their toxicity. This is a preliminary report related to the toxicities of oximes that may participate in the inactivation of mitochondrial oxidase enzymes. This hypothesis should be further investigated by in vivo study, including kinetic determination and free radical work.

Evaluation of mRNA-based approach for identification of saliva and semen.

Multiplex mRNA profiling by a reverse transcription-polymerase chain reaction (RT-PCR) has been reported in the last few years as a new approach for the identification of body fluids. We have also demonstrated the feasibility of identifying body fluids by using a real-time RT-PCR assay. Statherin (STATH) and histatin (HTN3), the selected genes for saliva, and protamin 2 (PRM2) and semenogelin 1 (SEMG1), those selected for semen, showed high specificity to these body fluids. Thus, the sensitivity and specificity of target genes were examined in body fluid stains. All target genes were detected in 0.1 microL 6-day-old stains, and showed high specificity in 7-day-old 30 microL stains. Furthermore, the stability of HTN3 in saliva stains was examined under various environmental conditions over time. The results showed that the degradation of mRNA in the stains was highly affected by wet conditions, and that light was also an important factor. However, mRNA was detectable in an older saliva stain (6 years old) and in an older semen stain (3.5 years old), both of which had been kept under dry and dark conditions. The stability of mRNA beyond our supposition may play an important role in developing new techniques for body fluid identification.

Staphylococcus aureus-superantigen decreases FKBP51 mRNA expression and cell-response to suppressive efficacy of a glucocorticoid in human peripheral blood mononuclear cells: possible implication of mitogen-activated protein kinase pathways.

Glucocorticoids are commonly used for treatment of chronic inflammatory diseases, while a number of patients show insensitivity to glucocorticoid treatment. The molecular basis of these individual differences in glucocorticoid pharmacodynamics has little been taken into account. Here we focus on the implication of Staphylococcus aureus-producing superantigen, such as toxic shock syndrome toxin-1 (TSST-1), in the glucocorticoid sensitivity of human peripheral blood mononuclear cells and cell-response to glucocorticoid to produce a transcript for FK506-binding protein (FKBP51). Peripheral blood mononuclear cell-sensitivity to glucocorticoid was assessed by a cell proliferation test. FKBP51mRNA expressions were determined by real-time reverse transcription-polymerase chain reaction (RT-PCR). We also compared concentrations of various cytokines produced in culture supernatant between concanavalin A- and TSST-1-stimulated peripheral blood mononuclear cells using a cytometric beads array. Mitogen-activated protein kinase (MAPK) phosphorylation activity in peripheral blood mononuclear cells stimulated with concanavalin A and TSST-1 was analyzed by a cell-based ELISA. Prednisolone markedly inhibited concanavalin A-induced peripheral blood mononuclear cell proliferation, but they scarcely inhibited TSST-1-induced peripheral blood mononuclear cell proliferation. The mean (S.D.) of immunosuppressant concentrations that would give 50% (IC(50)) values for prednisolone in concanavalin A-stimulated peripheral blood mononuclear cells was 52.6 (54.2) ng/ml, which was significantly lower than that in TSST-1-stimulated peripheral blood mononuclear cells, i.e., 574.2 (817.0) ng/ml (P<0.001). TSST-1-stimulated peripheral blood mononuclear cells for 48 h attenuated prednisolone-induced FKBP51mRNA expressions concomitantly with decreased sensitivity to the anti-proliferative effects of prednisolone. Concentrations of interleukin-2 (IL-2) produced from TSST-1-stimulated peripheral blood mononuclear cells were significantly higher than that from peripheral blood mononuclear cells stimulated with concanavalin A (P<0.0001). Both concanavalin A and TSST-1 enhanced the phosphorylation of extracellular signal-regulated kinase (ERK) and p38, whereas the level of c-jun terminal kinase (JNK) phosphorylation was only increased by TSST-1-stimulation in peripheral blood mononuclear cells. Furthermore, the decreased FKBP51mRNA by TSST-1was found to be recovered by JNK and mitogen-activated protein kinase (MEK)/ERK inhibitors. Our data suggest that TSST-1 reduces activity of glucocorticoid in peripheral blood mononuclear cells by JNK activation and subsequent production of IL-2. Therefore, JNK might be an attractive target for overcoming glucocorticoid insensitivity induced by TSST-1 in peripheral blood mononuclear cells.