Estimation of soil-to-plant transfer factors of radiocesium in 99 wild plant species grown in arable lands 1 year after the Fukushima 1 Nuclear Power Plant accident.

One year after the deposition of radionuclides from the Fukushima 1 Nuclear Power Plant (A formal name is Fukushima Daiichi Nuclear Power Station) in March 2011, radiocesium (¹³4Cs, ¹³7Cs) concentrations ([Cs]) were comprehensively investigated in the wild plants of 99 species most of which were annual or summer green perennial herbs and started to grow from April 2012 at the heavily contaminated fields of paddy (three study sites) and upland (one study site) in Fukushima Prefecture. The survey was conducted three times (April, July and October) in the year. In each site, soils (soil cores of 5-cm depth) and plants (aerial shoots) were collected for determination of [Cs] on a dry weight basis, and then the transfer factor (TF) of radiocesium from soil to plant ([Cs]plant/[Cs]soil) was estimated in each species. The [Cs] values of both soils and plants largely varied. However, some species exhibited relatively high TF values (more than 0.4) (e.g., Athyrium yokoscense, Dryopteris tokyoensis, and Cyperus brevifolius), while others exhibited almost negligible values (less than 0.01) (e.g., Salix miyabeana, Humulus scandens, and Elymus tsukushiensis). In addition, judging from the 11 species grown in both paddy and upland fields, TF values were generally higher in the paddy fields. The estimation of phytoextraction efficiency of soil radiocesium by weed communities in the paddy fields suggests that the weed community is not a practical candidate for phytoremediation technique.

The current status and novel advances of boron neutron capture therapy clinical trials.

Boron neutron capture therapy (BNCT) is a treatment method that focuses on improving the cure rate of patients with cancer who are difficult to treat using traditional clinical methods. By utilizing the high neutron absorption cross-section of boron, material rich in boron inside tumor cells can absorb neutrons and release high-energy ions, thereby destroying tumor cells. Owing to the short range of alpha particles, this method can precisely target tumor cells while minimizing the inflicted damage to the surrounding normal tissues, making it a potentially advantageous method for treating tumors. Globally, institutions have progressed in registered clinical trials of BNCT for multiple body parts. This review summarized the current achievements in registered clinical trials, Investigator-initiated clinical trials, aimed to integrate the latest clinical research literature on BNCT and to shed light on future study directions.

Serological identification of Tektin5 as a cancer/testis antigen and its immunogenicity.

BACKGROUND: Identification of new cancer antigens is necessary for the efficient diagnosis and immunotherapy. A variety of tumor antigens have been identified by several methodologies. Among those antigens, cancer/testis (CT) antigens have became promising targets. METHODS: The serological identification of antigens by the recombinant expression cloning (SEREX) methodology has been successfully used for the identification of cancer/testis (CT) antigens. We performed the SEREX analysis of colon cancer. RESULTS: We isolated a total of 60 positive cDNA clones comprising 38 different genes. They included 2 genes with testis-specific expression profiles in the UniGene database, such as TEKT5 and a CT-like gene, A kinase anchoring protein 3 (AKAP3). Quantitative real-time RT-PCR analysis showed that the expression of TEKT5 was restricted to the testis in normal adult tissues. In malignant tissues, TEKT5 was aberrantly expressed in a variety of cancers, including colon cancer. A serological survey of 101 cancer patients with different cancers by ELISA revealed antibodies to TEKT5 in 13 patients, including colon cancer. None of the 16 healthy donor serum samples were reactive in the same test. CONCLUSION: We identified candidate new CT antigen of colon cancer, TEKT5. The findings indicate that TEKT5 is immunogenic in humans, and suggest its potential use as diagnostic as well as an immunotherapeutic reagent for cancer patients.

Selective delivery of beta cell antigen to dendritic cells in vivo leads to deletion and tolerance of autoreactive CD8+ T cells in NOD mice.

Type 1 diabetes (T1D) is an autoimmune disease resulting from defects in central and peripheral tolerance and characterized by T cell-mediated destruction of islet beta cells. Cytotoxic CD8(+) T cells, reactive to beta cell antigens, are required for T1D development in the NOD mouse model of the disease, and CD8(+) T cells specific for beta cell antigens can be detected in the peripheral blood of T1D patients. It has been evident that in nonautoimmune-prone mice, dendritic cells (DCs) present model antigens in a tolerogenic manner in the steady state, e.g., in the absence of infection, and cause T cells to proliferate initially but then to be deleted or rendered unresponsive. However, this fundamental concept has not been evaluated in the setting of a spontaneous autoimmune disease. To do so, we delivered a mimotope peptide, recognized by the diabetogenic CD8(+) T cell clone AI4, to DCs in NOD mice via the endocytic receptor DEC-205. Proliferation of transferred antigen-specific T cells was initially observed, but this was followed by deletion. Tolerance was achieved because rechallenge of mice with the mimotope peptide in adjuvant did not induce an immune response. Thus, targeting of DCs with beta cell antigens leads to deletion of autoreactive CD8(+) T cells even in the context of ongoing autoimmunity in NOD mice with known tolerance defects. Our results provide support for the development of DC targeting of self antigens for treatment of chronic T cell-mediated autoimmune diseases.

The accelerator-based boron neutron capture reaction evaluation system for head and neck cancer.

The purpose of this study is to assess accelerator-based boron neutron capture reaction (BNCR) in human tumor cell lines by colony formation assay and modified high density survival assay (HDS assay). The results of post irradiation survival rate in human oral squamous cell carcinoma and osteosarcoma using both assays were similar. Therefore, HDS assay would be efficient to evaluate BNCR in not only tumor cells but also in normal cells as BNCT screening.

In Vitro Studies to Define the Cell-Surface and Intracellular Targets of Polyarginine-Conjugated Sodium Borocaptate as a Potential Delivery Agent for Boron Neutron Capture Therapy.

Boron neutron capture therapy (BNCT) requires pharmaceutical innovations and molecular-based evidence of effectiveness to become a standard cancer therapeutic in the future. Recently, in Japan, 4-borono-L-phenylalanine (BPA) was approved as a boron agent for BNCT against head and neck (H&N) cancers. H&N cancer appears to be a suitable target for BPA-BNCT, because the expression levels of L-type amino acid transporter 1 (LAT1), one of the amino acid transporters responsible for BPA uptake, are elevated in most cases of H&N cancer. However, in other types of cancer including malignant brain tumors, LAT1 is not always highly expressed. To expand the possibility of BNCT for these cases, we previously developed poly-arginine peptide (polyR)-conjugated mercaptoundecahydrododecaborate (BSH). PolyR confers the cell membrane permeability and tumor selectivity of BSH. However, the molecular determinants for the properties are not fully understood. In this present study, we have identified the cluster of differentiation 44 (CD44) protein and translational machinery proteins as a major cell surface target and intracellular targets of BSH-polyR, respectively. CD44, also known as a stem cell-associated maker in various types of cancer, is required for the cellular uptake of polyR-conjugated molecules. We showed that BSH-polyR was predominantly delivered to a CD44High cell population of cancer cells. Once delivered, BSH-polyR interacted with the translational machinery components, including the initiation factors, termination factors, and poly(A)-biding protein (PABP). As a proof of principle, we performed BSH-polyR-based BNCT against glioma stem-like cells and revealed that BSH-polyR successfully induced BNCT-dependent cell death specifically in CD44High cells. Bioinformatics analysis indicated that BSH-polyR would be suitable for certain types of malignant tumors. Our results shed light on the biochemical properties of BSH-polyR, which may further contribute to the therapeutic optimization of BSH-BNCT in the future.

Adsorption and removal of strontium in aqueous solution by synthetic hydroxyapatite.

Hydroxyapatite (HAP) is a main mineral constituent of bone and tooth and has an outstanding biocompatibility. HAP is a possible sorbent for heavy metals in wastewater due to its high adsorption capacity and low water solubility. We developed a removal system of 90Sr from aqueous solution by HAP column procedure. More than 90 % of 90Sr was adsorbed and removed from the 90Sr containing solution. Divalent cations, Ca2+, had little effect on the removal of 90Sr up to a concentration of 1 mmol L-1. This clearly indicates that the HAP column technique is advantageous with respect to the capacity to adsorb 90Sr from water present in the environment.

Oncogenic function of the homeobox A13-long noncoding RNA HOTTIP-insulin growth factor-binding protein 3 axis in human gastric cancer.

To study the mechanisms of gastric tumorigenesis, we have established CSN cell line from human normal gastric mucosa, and CS12, a tumorigenic and invasive gastric cancer cell line from CSN passages. Many stem cell markers were expressed in both CSN and CS12 cells, but LGR5 and NANOG were expressed only in CS12 cells. Increased expression of homeobox A13 (HoxA13) and its downstream cascades was significant for the tumorigenic activity of CS12 cells, and was associated with recruitment of E2F-1 to HoxA13 promoter accompanied with increased trimethylation of histone H3 lysine 4 (H3K4me3) at the hypomethylated E2F motifs. Knockdown of HoxA13 caused the downregulation of long non-coding RNA HOTTIP and insulin growth factor-binding protein 3 (IGFBP-3) genes, indicating that both were targets of HoxA13. Concurrent regulation of HoxA13-HOTTIP was mediated by the mixed lineage leukemia-WD repeat domain 5 complex, which caused the trimethylation of H3K4 and then stimulated cell proliferation. HoxA13 transactivated the IGFBP-3 promoter through the HOX-binding site. Activation of IGFBP-3 stimulated the oncogenic potential and invasion activity. Increased expression of HoxA13 (63.2%) and IGFBP-3 (28.6%) was detected in human gastric cancer tissues and was found in the gastric cancer data of The Cancer Genome Atlas. Taken together, the HoxA13-HOTTIP-IGFBP-3 cascade is critical for the carcinogenic characteristics of CS12 cells.

IGFBP-3 expression in hepatocellular carcinoma involves abnormalities in TGF-beta and/or Rb signaling pathways.

Insulin-like growth factor binding protein-3 (IGFBP-3) is a mediator of growth suppression signals and a putative tumor suppressor gene. The growth suppression mechanisms of IGFBP-3 have not been well clarified. We examined the expression of IGFBP-3 transcripts in human hepatocellular carcinoma (HCC) and the relationship between IGFBP-3 expression and the transforming growth factor-beta (TGF-beta) and/or retinoblastoma (Rb) signaling pathways. In situ hybridization revealed IGFBP-3 transcripts in cancer cells in 6 of 57 (10%) HCCs, including moderately and poorly differentiated HCCs with intrahepatic metastasis. In contrast, all lung metastatic nodules of 4 HCCs showed IGFBP-3 transcripts in cancer cells. The cDNA microarray showed that genes for the TGF-beta pathway and Rb were up-regulated in IGFBP-3-expressing HCCs. In 6 HCCs presenting IGFBP-3, immunohistochemical analyses showed abnormalities in the TGF-beta and/or Rb pathways; the loss of phosphorylated-Smad2 was observed in 2, and overexpression of phosphorylated-Rb was observed in the remaining 4 HCCs. The present study suggests that IGFBP-3 mediates growth suppression signals via the TGF-beta and/or Rb pathways in HCC.

Functional promoter upstream p53 regulatory sequence of IGFBP3 that is silenced by tumor specific methylation.

BACKGROUND: Insulin-like growth factor binding protein (IGFBP)-3 functions as a carrier of insulin-like growth factors (IGFs) in circulation and a mediator of the growth suppression signal in cells. There are two reported p53 regulatory regions in the IGFBP3 gene; one upstream of the promoter and one intronic. We previously reported a hot spot of promoter hypermethylation of IGFBP-3 in human hepatocellular carcinomas and derivative cell lines. As the hot spot locates at the putative upstream p53 consensus sequences, these p53 consensus sequences are really functional is a question to be answered. METHODS: In this study, we examined the p53 consensus sequences upstream of the IGFBP-3 promoter for the p53 induced expression of IGFBP-3. Deletion, mutagenesis, and methylation constructs of IGFBP-3 promoter were assessed in the human hepatoblastoma cell line HepG2 for promoter activity. RESULTS: Deletions and mutations of these sequences completely abolished the expression of IGFBP-3 in the presence of p53 overexpression. In vitro methylation of these p53 consensus sequences also suppressed IGFBP-3 expression. In contrast, the expression of IGFBP-3 was not affected in the absence of p53 overexpression. Further, we observed by electrophoresis mobility shift assay that p53 binding to the promoter region was diminished when methylated. CONCLUSION: From these observations, we conclude that four out of eleven p53 consensus sequences upstream of the IGFBP-3 promoter are essential for the p53 induced expression of IGFBP-3, and hypermethylation of these sequences selectively suppresses p53 induced IGFBP-3 expression in HepG2 cells.

Reduced expression of insulin-like growth factor binding protein-3 and its promoter hypermethylation in human hepatocellular carcinoma.

Insulin-like growth factor binding protein-3 (IGFBP-3) is postulated to be a mediator of growth suppression signals. Reduced expression of the IGFBP-3 was observed in nine out of 12 human hepatocellular carcinomas (HCC) (75%). Promoter hypermethylation of the IGFBP-3 was detected in four out of 12 HCCs (33%) although mutations were not identified. The expression of IGFBP-3 was restored by the demethylating agent 5-aza-2'-deoxycytidine in HCC cell line with promoter hypermethylation (HepG2). As IGFBP-3 functions like a tumor suppressor gene, it may be used as a therapeutic target for HCC.

Genome aberrations observed by restriction landmark genome scanning analysis of chromosomal DNA in various types of primary hepatocellular carcinoma.

BACKGROUND/AIMS: The genes responsible for hepatocellular carcinoma have not been identified. To identify the relevant genes of hepatocellular carcinoma, detailed and comprehensive information of genomic aberrations must be obtained. To reveal the chromosomal aberrations in hepatocellular carcinoma, we carried out a restriction landmark genome scanning analysis of various types of hepatocellular carcinoma. METHODOLOGY: Samples of various types of hepatocellular carcinoma, including two with multinodular-hepatocellular carcinomas, one hepatocellular carcinoma showing nodules in a nodule pattern, one hepatocellular carcinoma metastasized to different tissues, three small (< 2.0 cm) hepatocellular carcinomas and four large (> 5.0 cm) hepatocellular carcinomas were examined by the restriction landmark genome scanning method with corresponding non-hepatocellular carcinoma tissues. Restriction enzyme Not I was used as a landmark enzyme, Eco RV was used as a fragmentation enzyme, and Hin fI was used as a digestion enzyme in the gel for two-dimensional electrophoresis. RESULTS: We observed spot aberrations with different origins. Frequently observed spot aberrations originated from the change in the methylation status of repetitive sequences. No clear correlation between the pathological grade and the number or type of spot aberrations was observed. CONCLUSIONS: We demonstrated that major aberrations of restriction landmark genome scanning spots originated from the change of methylation status in hepatocellular carcinoma.

A purification system for 64Cu produced by a biomedical cyclotron for antibody PET imaging.

Ion exchange is a simple and efficient method for separating no-carrier-added 64Cu from an irradiated Ni target. We developed a semi-automated two-round 64Cu separation system equipped with a strong-base anion exchange resin column. We first verified the efficiency of the system using a non-radioactive substitute consisting of 25 mg of Ni and 127 ng of Cu, and confirmed that Cu was completely eluted at the second round of the separation step. After the bombardment, separation of 64Cu from the Ni target was achieved with high radiochemical purity. 64Cu produced and separated in this study had an extremely low level of Ni impurity. It could be used for labeling monoclonal antibodies for antibody positron emission tomography imaging and synthesizing radiopharmaceuticals.

Isolation and characterization of human lung cancer antigens by serological screening with autologous antibodies.

Serological analysis of a recombinant cDNA expression library (SEREX) derived from two lung adenocarcinoma cancer cell lines using autologous sera led to the isolation of 41 positive cDNA clones comprising 28 different antigens. They coded for a variety of nuclear and cytoplasmic proteins. Among the antigens, nucleoporin 107 (NUP107) was isolated most frequently (5 of 41 clones). The second most frequently isolated antigen was coded for by C21orf58 (4 of 41 clones). During serological analysis of selected antigens based on their reactivity to sera from normal individuals and lung cancer patients, none of the antigens showed a cancer-restricted recognition pattern. However, five genes including NUP107 showed higher expression when we examined the changes in gene expression in five different adenocarcinoma cell lines, including those used in SEREX, compared with their levels in normal lung tissues by cDNA microarray analysis. On the other hand, the expression levels of five genes including C21orf58 were down regulated in all adenocarcinoma cell lines. This SEREX study combining comprehensive gene expression assays has added to the growing list of lung cancer antigens, which may aid the development of diagnostic and immunotherapeutic reagents for patients with lung cancer.

Aberrant promoter methylation of insulin-like growth factor binding protein-3 gene in human cancers.

Insulin-like growth factor binding protein-3 (IGFBP-3) is postulated to be a mediator of growth suppression signals. Here, we examined the methylation status of IGFBP-3 to correlate to clinicopathological factors in human cancers. The methylation status of IGFBP-3 was determined by bisulfite DNA sequencing and was correlated with expression semi-quantified by real-time RT-PCR to develop a methylation-specific PCR (MSP) assay for IGFBP-3. Using the MSP assay, we examined the methylation status of IGFBP-3 in gastric cancer (GC), colorectal cancer (CRC), breast cancer (BC) and malignant mesothelioma (MM). IGFBP-3 methylation was detected in 6 of 13 (46%) and 16 of 24 (67%) GC cell lines and tumors, respectively; 4 of 8 (50%) and 15 of 26 (58%) CRC cell lines and tumors, respectively; 3 of 11 (27%) and 7 of 39 (18%) BC cell lines and tumors, respectively and 1 of 5 (20%) and 18 of 56 (32%) MM cell lines and tumors, respectively. Interestingly, the methylation status of MM specimens from Japanese patients (75%, 12 out of 16 patients) was significantly higher than those from the USA (15%, 6 out of 40 patients) (p < 0.0001), suggesting the presence of ethnic differences in the IGFBP-3 methylation status. We also found that IGFBP-3 methylation was preferentially present in GCs arising in the lower-third of the stomach (p = 0.079). In summary, our results showed that IGFBP-3 methylation played an important role in the silencing of its expression, suggesting that IGFBP-3 may act as a tumor suppressor gene in several human cancers examined.

Altered expression of vascular endothelial growth factor, fibroblast growth factor-2 and endostatin in patients with hepatocellular carcinoma.

BACKGROUND: Advanced hepatocellular carcinoma (HCC) in humans is characterized by hypervascularity. In the present study, the expressions of vascular endothelial growth factor (VEGF), basic fibroblast growth factor (FGF-2) and endostatin were analyzed in patients with chronic liver disease to clarify the effect of these major angiogenic factors. METHODS: Serum concentrations of VEGF, FGF-2 and endostatin in 24 patients with HCC, 16 patients with liver cirrhosis (LC) and 13 healthy volunteers were measured by enzyme-linked immunosorbent assay. The expression of VEGF in 21 surgically resected HCC samples was analyzed by immunohistochemistry, and that of VEGF isoforms in 15 HCC samples was assessed by reverse transcriptase-polymerase chain reaction (RT-PCR). RESULTS: Serum VEGF, FGF-2 and endostatin concentrations were significantly elevated in patients with HCC compared with healthy volunteers; but there was no significant difference between patients with HCC and those with non-HCC liver disease. Immunohistochemical analysis showed that VEGF protein was strongly expressed in both well-differentiated HCC cells and non-cancerous hepatocytes, whereas in moderately and poorly differentiated HCC the expression was stronger in the endothelial cells (EC) lining intratumor vessels than in the cancer cells. On RT-PCR for VEGF isoforms it was found that VEGF-121, VEGF-165 and VEGF-189 were expressed in all but one of the HCC samples and in all corresponding non-HCC samples. CONCLUSIONS: The results suggest that VEGF, FGF-2, and endostatin concentrations are elevated prior to the emergence of HCC and that the distribution of VEGF changes dynamically during the development of HCC.

Decreased expression of B7 costimulatory molecules and major histocompatibility complex class-I in human hepatocellular carcinoma.

BACKGROUND AND AIM: We analyzed the expression of antigen-processing and antigen-presenting molecules in surgically resected fresh samples of human hepatocellular carcinoma (HCC) tissue to elucidate a mechanism of immune escape. We also examined the expression of interleukin (IL)-10 protein, which might act to downregulate expression of antigen-processing and antigen-presenting molecules. METHODS: Twenty-eight HCC samples obtained by surgical resection were analyzed for the expression of beta2-microglobulin, heat-shock protein (HSP)-70, human leukocyte antigen (HLA) class-I, CD80 (B7-1), CD86 (B7-2) and IL-10 by immunostaining. RESULTS: Beta2-microglobulin and HSP-70 were preserved in all samples. In contrast, the expression of HLA class-I molecules was significantly reduced according to lowering in the histological grading of tumor differentiation (P = 0.024). Furthermore, B7-1 and B7-2 expression was reduced in tumor cells compared with corresponding areas of liver tissue without malignant involvement irrespective of the histological grading of tumors (21% and 36%, respectively). Although IL-10 protein was expressed in 54% of HCC, no relationship between the expression of IL-10 and downregulation of B7-1, B7-2, and HLA class-I was evident. CONCLUSION: These findings suggest the potential role of B7 co-stimulatory molecules and HLA class-I molecules in facilitating HCC escape from immune surveillance without the involvement of IL-10.

Telomerase reverse transcriptase gene amplification in hepatocellular carcinoma.

BACKGROUND AND AIM: Telomerase activation is essential for the immortality of cancer cells. The expression of telomerase reverse transcriptase (hTERT), the catalytic component of the telomerase complex, regulates telomerase activity in human cancers. Amplification of the hTERT gene, located at chromosome 5p, is thought to be a potential genetic event contributing to telomerase activation in sporadic tumors. METHODS: The amplification of the hTERT gene was examined in 46 surgically resected hepatocellular carcinomas (HCC) by real-time polymerase chain reaction and the status was compared with the expression of hTERT mRNA and clinicopathological parameters. RESULTS: Amplified hTERT genes were found in 21.7% (10/46) of HCC. The incidence of amplified hTERT genes in poorly differentiated HCC (6/12, 50%) was significantly higher than that in highly to moderately differentiated HCC (4/34, 11.8%; P = 0.012). Tumor size in those cases with hTERT gene amplification was larger compared to those cases with no amplification (P = 0.047). Amplification of the hTERT gene was not observed in non-cancerous tissues. The hTERT mRNA level did not correlate with the number of hTERT genes. CONCLUSIONS: Based on these results, it is thought that hTERT gene amplification is a cancer-specific event, and may furthermore contribute to the dedifferentiation and development of HCC. However, hTERT gene overexpression was rarely due to an increased hTERT gene copy number in HCC.

Serum gamma-interferon-inducing factor (IL-18) and IL-10 levels in patients with acute hepatitis and fulminant hepatic failure.

BACKGROUND AND AIMS: The aim was to determine the role of T-helper (Th)1/Th2 cytokine responses in the clinical outcome of patients with acute liver injury. METHODS: The serum levels of the cytokines, interleukin (IL)-18, gamma-interferon (IFN-gamma), IL-10 and IL-4 were measured in 20 fulminant hepatic failure (FHF), 18 acute hepatitis (AH), 30 chronic viral hepatitis and 20 liver cirrhosis (LC) patients. Thirteen cases were from the intensive care unit (ICU) and there were 21 healthy volunteers. Immunohistochemical staining of liver biopsies for IL-18 expression was also performed. RESULTS: Serum IL-18 levels in patients with FHF were significantly more elevated than in patients with other liver diseases, ICU cases and healthy volunteers. Furthermore, serum IFN-gamma levels in patients with FHF were also significantly higher than in patients with chronic viral hepatitis, LC and healthy volunteers. We found a positive correlation between the levels of IL-18 and IFN-gamma. However, no relationship was observed between these and clinical outcome. In immunohistochemical staining, CD68+ macrophage cells and IL-18-positive cells were observed in portal zones. Elevated serum IL-10 levels were restricted to patients presenting with FHF, and were significantly higher in surviving cases (P < 0.01). Furthermore, serum IL-10 levels, but not IL-4 levels, were inversely correlated with serum total bilirubin concentrations (P = 0.045) and the death rate (p) outlined in Japan (P = 0.030). CONCLUSION: These results suggest that IL-18 and IFN-gamma are involved in the pathogenesis of acute hepatic injury in humans, and that, in particular, elevated serum levels of IL-10 may be predictive of improved outcomes for these patients.

Quantitative analysis of p40/p46 and p69/p71 forms of 2',5'-oligoadenylate synthetase mRNA by competitive PCR and its clinical application.

BACKGROUND: 2',5'-Oligoadenylate synthetases (2-5AS) are type I interferon (IFN)-induced proteins with antiviral capacity. Three major forms of 2-5AS with distinct enzymatic activities have been described in IFN-treated human cells. We measured distinct forms of 2-5AS mRNA to analyze the relationship with its enzymatic activity and response to IFN therapy in chronic hepatitis C. METHODS: We established a method to quantify p40/p46 and p69/p71 forms of 2-5AS mRNA by use of reverse transcription followed by competitive PCR. The 2-5AS mRNA concentrations were measured in peripheral blood mononuclear cells from 40 patients with chronic hepatitis C and 28 control individuals. RESULTS: Reconstitution experiments and comparison with Northern blot analyses revealed that our method accurately and linearly quantified 2-5AS mRNA. 2-5AS mRNA concentrations and 2-5AS enzymatic activity were correlated (P <0.03). Our data demonstrated a correlation in 2-5AS mRNA between p40/p46 and p69/p71 (P <0.02), indicating a similar regulation of the expression of these genes. Our data also demonstrated that pretreatment concentrations of 2-5AS mRNA correlated with responses to IFN therapy in chronic hepatitis C. CONCLUSIONS: Our method for measuring 2-5AS mRNA concentrations could provide an important marker for selecting patients for IFN therapy and may be useful for the development of more effective therapeutic strategies for chronic hepatitis C.