Recently, because of its low toxicity and biological effects, chitosan has been widely used in the medical and pharmaceutical fields, e.g., for nasal or oral delivery of peptide or polar drug delivery. Here, we report a growth-inhibitory effect of chitosan on tumor cells. The growth inhibition was examined by WST-1 colorimetric assay and cell counting. We also observed DNA fragmentation, which is characteristic of apoptosis, and elevated caspase-3-like activity in chitosan-treated cancer cells. The findings suggest that chitosan may have potential value in cancer therapy.

No abstract

Epithelial-mesenchymal transition (EMT) and changes in the expression of the microRNA-200 (miR-200) family were examined in the human colorectal cancer (CRC) cell line SW620 with acquired oxaliplatin (L-OHP) resistance. Two CRC cell lines, SW480, derived from primary CRC, and SW620, derived from lymph node metastasis, which were obtained from the same patient, were used in the present study. L-OHP-resistant SW620 cells were obtained by exposure to L-OHP for 155 d. The concentration of L-OHP was increased to 80 µM in a stepwise manner. The IC50 value of L-OHP was increased 16-fold in L-OHP-resistant SW620 cells, which also displayed mesenchymal cell-like characteristics, such as the down-regulation of E-cadherin and up-regulation of vimentin. However, L-OHP-resistant SW480 cells were not obtained when the concentration of L-OHP was increased in a similar stepwise manner. The expression levels of members of the miR-200 family (miR-200a, miR-200b, miR-429, miR-200c, and miR-141) were significantly higher in SW480 cells than in SW620 cells. The expression levels of miR-200c and miR-141 were significantly lower in L-OHP-resistant SW620 cells than in control SW620 cells. L-OHP-resistant SW620 cells did not exhibit cross-resistance to other anti-cancer drugs used to treat CRC, such as 5-fluorouracil, irinotecan, and the active metabolite of irinotecan (SN-38). These results suggest that the down-regulated expression of miR-200c and miR-141 plays a role in selective resistance to L-OHP and EMT in CRC cells during repeated treatments with L-OHP.

We studied the genotypes of polymorphic N-acetyltransferase (NAT2) in 145 Japanese subjects by the polymerase chain reaction-restriction fragment length polymorphism method. The rapid-type NAT2*4 was expressed at a higher frequency (68.6%) than the slow-type genes with specific point mutations (NAT2*6A, 19.3%; NAT2*7B, 9.7%; NAT2*5B, 2.4%). The frequency of NAT2* genotypes consisted of 44% of a homozygote of NAT2*4, 49% of a heterozygote of NAT2*4 and mutant genes, and 7% of a combination of mutant genes. The metabolic activity for procainamide to N-acetylprocainamide was measured in 11 healthy subjects whose genotype had been determined. Although the acetylation activity substantially varied interindividually, the variability was considerably reduced after classification according to the genotype. The N-acetylprocainamide/procainamide ratio in urinary excretion was 0.60 +/- 0.17 (mean +/- SD) for those with NAT2*4/*4, 0.37 +/- 0.06 for NAT2*4/*6A, 0.40 +/- 0.03 for NAT2*4/*7B, and 0.17 for NAT2*6A/*7B. The results indicated that the NAT2* genotype correlates with acetylation of procainamide.

Rhinacanthus nasutus (L.) KURZ (Acanthaceae) is a shrub widely distributed in South China and India. In this study, the antiproliferative activity of the ethanol extract of root and aqueous extract of leaves of R. nasutus, and the supposed active moiety rhinacanthin C was assessed in vitro using the human cervical carcinoma cell line HeLa, its MDR1-overexpressing subline Hvr100-6, human prostate carcinoma PC-3 cells and human bladder carcinoma T24 cells. Rhinacanthin C was chemically synthesized and its content in the R. nasutus extracts was determined by HPLC with a photodiode array detector. The antiproliferative activity of the R. nasutus extracts was also assessed in vivo using sarcoma 180-bearing mice. It was suggested that 1) the in vitro antiproliferative activity of rhinacanthin C was comparable with or slightly weaker than that of 5-FU, 2) rhinacanthin C showed antiproliferative activity for MDR1-overexpressing Hvr100-6 cells, similarly to parent HeLa cells, 3) the in vitro antiproliferative activity of the ethanol extract of root R. nasutus was due to rhinacanthin C, whereas that of the aqueous extract of leaves of R. nasutus was due to constituents other than rhinacanthin C, and 4) both of the R. nasutus extracts showed in vivo antiproliferative activity after oral administration once daily for 14 d.

No abstract

The effects of decitabine (DAC), a DNA methyltransferase (DNMT) inhibitor, on metastasis and exosomal expression of microRNAs were examined in SW620/OxR cells, a human colorectal cancer (CRC) cell line (SW620) with acquired resistance to oxaliplatin. This cell line shows an invasive phenotype by epithelial-mesenchymal transition. Two CRC cell lines, SW480, derived from primary CRC, and SW620, derived from lymph node metastasis, which were obtained from the same patient, as well as SW620/OxR, were also used in the present study. Cytarabine (Ara-C), a non-DNMT-inhibiting cytidine analog, was used as negative control of DAC. No significant difference was observed in the invasion abilities of SW480 cells treated with DAC or Ara-C. On the other hand, invasion ability was suppressed by treatment with DAC in SW620 and SW620/OxR cells. Up-regulated expression of E-cadherin, microRNA-200c (miR-200c), and miR-141 following DAC treatment indicated the acquisition of epithelial cell-like characteristics in SW620 and SW620/OxR cells. Exosomal expression levels of miR-200c and miR-141 were also up-regulated by DAC treatment in SW620 and SW620/OxR but not in SW480 cells. This increase in exosomal miRNA expression negatively correlated with invasion ability. These results suggest that DNA demethylation treatment caused acquisition of epithelial cell-like characteristics in SW620 and SW620/OxR cells. Furthermore, the observed increased exosomal expression of miR-200c and miR-141 may be an indicator or biomarker candidate for mesenchymal-epithelial transition of CRC cells.

In the early 1950s, isoniazid (INH) was developed as chemotherapeutic agent for the treatment of tuberculosis. 2)However, serious side effects including peripheral neuritis and hepatic toxicity were recognized in some patients, despite their dosage being similar to that taken by others. Previous studies indicated that INH was catabolized to inactive Nacetylisoniazid (AcINH) by N-acetyltransferase2 (NAT2) (Fig. 1), and that the interindividual variation of plasma concentration and urinary recovery of INH were characterized by a bimodal or trimodal distribution. 3,4) N-acetylation of INH is reported to be genetically determined in a simple Mendelian fashion, and the frequencies of rapid (and/or intermediate) and slow acetylator of INH is different among racial populations. 5) There have been studies on the relationships between the acetylator phenotype and the efficacy or side effects of INH. The rapid acetylators should take larger doses of INH than slow acetylators, 6) and slow acetylators are at risk of adverse reactions such as peripheral neuritis, 4) hepatic toxicity 4,7) and systemic lupus erythematosus-like syndromes.8,9) These findings strongly suggested the necessity of therapeutic drug monitoring (TDM) in blood or serum to define the most appropriate dosage regimen for each individual. 10,11) Recently, Deguchi and his colleagues defined four NAT2 alleles, the wild-type allele (NAT2*4) and three mutant alleles (NAT2*5B, NAT2*6A and NAT2*7B), which could explain 93-97.5% of the trimodal INH acetylator phenotype among Japanese healthy subjects.12,13) An individual INH N-acetyltransferase2 (NAT2). In the present study, the relationship between the NAT2 genotype and the INH acetylator phenotype was examined in Japanese tuberculous patients and compared with healthy subjects. Subjects were classified according to the genotyping into NAT2*5B (allele4), NAT2*6A (allele3) and NAT2*7B (allele2), using the PCR-RFLP method. Twelve healthy subjects and 7 tuberculous patients participated in the INH acetylator phenotyping study, in which each subject was administered an oral dose of INH, followed by urine sampling for 24 h. Urinary concentrations of INH and N-acetylisoniazid (AcINH) were measured by the HPLC method. The urinary recoveries of INH (% of dose) in healthy subjects in relation to NAT2 genotyping were as follows: 6.4؎2.2 in the homozygotes for the wild-type allele, 10.7؎ 2.2 in the compound heterozygotes for the mutant allele, and 38.6؎6.4 in the homozygotes for the mutant allele. In the patients study, the findings in the corresponding three groups were 4.0؎1.7, 8.8 and 18.3؎9.3. Although no significant difference was found because of the lower systemic exposure of INH in patients compared with healthy subjects, there were differences in the disposition kinetics of INH between subjects with and without mutations in the NAT2 gene, and these findings were observed not only in healthy subjects but also in patients who had comedicated drugs and hepatic dysfunctions. The findings indicated that the metabolism ...