Increased expression of insulin-like growth factor i is associated with Ara-C resistance in leukemia

Resistance to cytosine arabinoside (Ara-C) is a major problem in the treatment of patients with acute myeloid leukemia (AML). In order to investigate the mechanisms involved in Ara-C resistance, the gene expression profile of Ara-C-resistant K562 human myeloid leukemia cells (K562/AC cells) was compared to that of Ara-C-sensitive K562 cells (K562 cells) by using a cDNA microarray platform. Correspondence analysis demonstrated that insulin-like growth factor I (IGF-I) gene was upregulated in K562/AC cells. The biological significance of IGF-I overexpression was further examined in vitro. When K562 cells were incubated with IGF-I ligand, they were protected from apoptosis induced by Ara-C. In contrast, a significant inhibition of growth and increase of apoptosis of K562/AC cells were induced by IGF-I receptor neutralizing antibody, or suramin, a nonspecific growth factor antagonist. Moreover, from the analysis of 27 AML patients, we have shown that IGF-I expression levels are higher in patients at refractory stage, after Ara-C combined chemotherapy, than those in patients at diagnosis. These results suggest that the inhibition of IGF-I and its downstream pathway is a valuable therapeutic approach to overcome Ara-C resistance in AML.     

Molecular profiles of the mouse postnatal development of the esophageal epithelium showing delayed growth start

Studies on molecular mechanisms of self-renewal in normal stem cells are required for understanding the cancer stem cell. Self-renewal in many kinds of normal stem cells might be accelerated in the growth of a young organism and in the repair of damaged tissue. This study examined whether the esophagus in growing neonates provides an experimental system for studies on epithelial stem cell renewal. The esophageal epithelium consists of 3 layers, from the luminal side to the bottom: the differentiated, epibasal and basal cell layers. The basal cell layer is known to contain the stem cells for the esophageal epithelium. This basic architecture is observed both in mice and humans. We investigated the basal cells in the mouse neonate by immunostaining with a basal cell marker, nerve growth factor receptor (Ngfr), and compared the basal cell content in the esophageal epithelium between mice and humans. A mouse esophageal epithelial cell primary culture system was developed for studies on the basal cell growth and keratinocyte differentiation, and microarray analysis was conducted for obtaining expression profiles of the basal cells. It was revealed that the growth of the esophageal epithelium begins from postnatal day 3, and that the timing is consistent with membrane localization of Ngfr in the basal cell. An increase in the basal cell number by Ngf treatment is observed in in vitro mouse esophageal epithelium cultures. Furthermore, mRNA overexpression of Pdgfrb encoding platelet derived growth factor receptor beta and Egfr encoding epidermal growth factor receptor is associated with the timing of the growth of the esophageal epithelium in the neonatal mice. This study provides a new experimental model for studies on the growth of the basal cells, which are considered to include the stem cells, and on the enlargement of the body size in young organisms.     

Polymerase chain reaction (PCR)-based molecular discrimination between Paragonimus westermani and P. miyazakii at the metacercarial stage

The metacercariae of the lung flukes, Paragonimus westermani and P. miyazakii, are of known medical importance as the pathogens causing human paragonimiasis. They are both found in the same freshwater crab species in Japan and are morphologically quite similar. The aim of the present study was to establish molecular methods for accurate discrimination between individual metacercariae of the two species. In the first step, we amplified and sequenced the second internal transcribed spacer (ITS2) region of ribosomal DNA. Searches of nucleotide databases revealed that the ITS2 sequences generated from the metacercarial DNA were identical to those previously reported for the adults of the respective species. Utilizing a nucleotide difference between the two species, we have established two PCR-based techniques; PCR-restriction fragment length polymorphism and direct PCR-amplification using species-specific primers. Both techniques showed that the individual metacercariae of the two species could be unequivocally discriminated from one another. The present results suggest that the ITS2 region is useful for species discrimination irrespective of the life cycle stages of the lung flukes. Established techniques can thus be used for epidemiological investigations of the prevalence of human lung fluke metacercariae.     

Randomized Controlled Trial of Bixalomer Versus Sevelamer Hydrochloride in Hemodialysis Patients With Hyperphosphatemia

Hyperphosphatemia is a prognostic factor for morbidity and mortality in chronic kidney disease. Bixalomer is a nonabsorbable polymer that decreases serum phosphate levels by binding phosphate in the gastrointestinal tract. This study compared the efficacy and safety of bixalomer versus sevelamer hydrochloride for controlling hyperphosphatemia in hemodialysis patients. This was a multicenter, randomized open‐label, non‐inferiority study. The primary endpoint was serum phosphate on completion of treatment. Administration of bixalomer was started at 1.5 g/day and adjusted to a maximum of 7.5 g/day depending on the serum phosphate level. Sevelamer hydrochloride was started at 3.0 or 6.0 g/day and adjusted to a maximum of 9.0 g/day. Treatment was continued for 12 weeks. Fifty‐five patients were randomized to each treatment group. After 12 weeks, the baseline adjusted mean serum phosphate level was 5.87 mg/dL in the bixalomer group and 5.55 mg/dL in the sevelamer group, with a difference of 0.31 mg/dL and 95% confidence interval (CI) of [?0.13 to 0.76]. The upper limit of the 95%CI for the difference of the mean serum phosphate level between the two groups was <1.0 mg/dL, which was the non‐inferiority margin in this study. Thus, non‐inferiority of bixalomer to sevelamer was confirmed. The incidence of adverse events was lower in the bixalomer group, and bixalomer did not promote acidosis. Bixalomer achieved a similar reduction of serum phosphate to sevelamer, while causing fewer adverse reactions. Consequently, the usefulness of bixalomer for treating hyperphosphatemia was confirmed.     

Relationships between the expression of thymidylate synthase,dihydropyrimidine dehydrogenase,and orotate phosphoribosyltransferase and cell proliferative activity and 5-fluorouracil sensitivity in colorectal carcinoma

Background: The site of action of the 5-fluorouracil (5-FU) antitumor effect has been explicated in recent years. Many studies have investigated enzymes involved in 5-FU metabolism in attempts to predict this effect, and a correlation of enzyme activity with the 5-FU drug sensitivity test has been reported. The aim of this study was to identify the biochemical response determinants of 5-FU. Additionally, we aimed to clarify the association between cell proliferative activity and the response to 5-FU of colorectal cancer. Methods: Our research subjects were 54 patients with colorectal carcinoma who had undergone operations between August 1999 and July 2001 in our department. Assays of thymidylate synthase (TS), dihydropyrimidine dehydrogenase (DPD), and orotate phosphoribosyltransferase (OPRT) activities in colorectal carcinoma tissue and assays of 5-FU sensitivity by the collagen gel droplet embedded culture drug sensitivity test (CD-DST) were conducted to investigate the relationships between each enzyme activity and 5-FU sensitivity. In addition, the proliferative activity of cancer cells was evaluated with Ki-67 antibody, and the relationship of this activity to each enzyme activity and 5-FU sensitivity were investigated. Results: 5-FU sensitivity was high in the low-TS-activity group and in the high-OPRT-activity group. Cancers with high cell proliferative activity showed good sensitivity to 5-FU, and TS and OPRT activities were high in such cancers. Conclusion: The results suggest that OPRT activity can predict sensitivity to 5-FU, and high OPRT activity may cause good 5-FU sensitivity in cancers with high cell proliferative activity. Received: April 23, 2002 / Accepted: January 20, 2003 Correspondence to:R. Fujii     

Clonal evolution from trisomy into tetrasomy of chromosome 8 associated with the development of acute myeloid leukemia from myelodysplastic syndrome

Tetrasomy 8, though rare, is usually associated with trisomy 8, a far more common chromosomal abnormality in acute myeloid leukemia (AML). Yet the clonal relationship between trisomy 8 and tetrasomy 8 in the cases with these chromosomal abnormalities has been unclear. Here, we report a case of a 17-year-old male, diagnosed as having a myelodysplastic syndrome (MDS). Chromosome analysis showed the presence of trisomy 8. Five years later, he developed overt AML exhibiting tetrasomy 8 only. After chemotherapy, the blast cells in the bone marrow decreased to 3.4%, and the karyotype showed trisomy 8 alone. Fluorescence in situ hybridization using a probe specific for chromosome 8 showed that the percentages of cells exhibiting 2/ 3 /4 signals were 7.8/89.2/2.0 at the MDS stage, 20.5/36.1/41.0 when overt AML developed and 24.0/72.1/2.4 after chemotherapy. These results suggested that tetrasomy 8 is derived from the AML clone, possibly evolved from the MDS clone with trisomy 8. To our knowledge, this is the first detailed case report of clonal evolution from trisomy 8 into tetrasomy 8 associated with the development of AML from MDS.     

Safety and efficacy of low-dose liposomal amphotericin B as empirical antifungal therapy for patients with prolonged neutropenia

Background

Liposomal amphotericin B (L-AmB) is recommended as an empirical antifungal treatment for patients at increased risk of fungal infections although renal toxicity remains a clinical problem. We therefore conducted a pilot study to evaluate the safety and efficacy of low-dose L-AmB as an empirical antifungal therapy for patients with prolonged neutropenia.

Methods

High-risk patients with hematological malignancies were eligible to enroll in this study provided they had: exhibited neutropenia for at least 1 week; suffered from high-grade fever for 4 days despite treatment with a broad-spectrum antibacterial; and no identified fever-causing pathogen. Low-dose L-AmB (1 mg/kg) was administrated as empirical antifungal therapy.

Results

Sixteen patients were registered and, of these, data from the13 patients who did not receive allogeneic stem cell transplantation were analyzed. The median duration of low-dose L-AmB treatment was 8 days. Hypokalemia was seen in one patient: administration of potassium supplements for 10 days restored potassium levels to the normal range. A two-fold increase in creatinine levels was not found in any patients even those taking concomitant nephrotoxic drugs (e.g., amynoglycoside) during the study. One patient stopped receiving the drug due to an infusion-related adverse event. No patients showed breakthrough fungal infections or died during therapy or within 7 days after the end of the study. Increase in the L-AmB dose was necessary due to persistent fever in three patients who withdrew from the study. The satisfactory response rate for low-dose L-AmB was 69 %.

Conclusion

This study suggests that low-dose L-AmB may be an effective option as empirical antifungal therapy for high-risk patients with febrile neutropenia.