No Association of AS3MT Gene Polymorphisms with Susceptibility to Hepatotoxicity in APL Patients Treated with AS2O3: A Single-Center Study

Abstract

Background: Arsenic three oxide (As2O3) is the treatment choice for acute promyelocytic leukemia (APL). Little is known about possible risk factors with predictive value for toxicity caused by As2O3. Biomethylation is considered to be a major pathway of detoxification for inorganic arsenics (iAs). Arsenic Methyltransferase (AS3MT) is one of the key enzymes involved in the transfer of a methyl group from S-adenosyl-L-methionine to trivalent arsenical and plays a critical role in arsenic detoxification. Polymorphisms in hAS3MT lead to a change in the catalytic activity of the enzyme and may increase the risk of arsenic-related toxicity. In this study, we investigated the association of the AS3MT polymorphisms (rs11191439, rs3740390, and rs3740393) genes with hepatotoxicity in APL patients treated with As2O3. Materials and Methods: Genotyping was performed in 140 adult patients with APL treated with As2O3 using PCR-RFLP for rs11191439 and tetra-primer ARMS-PCR for rs3740390 and rs3740393. The results of PCR-RFLP and ARMS-PCR were confirmed by direct sequencing of 10 % of DNA samples. The results were analyzed using SNPStats, SPSS, and FinchTV. Hepatotoxicity was graded according to the National Cancer Institute's Common Toxicity Criteria (CTC). Results : Hepatotoxicity was seen in 52 of the 140 patients (37.1%), with grades I and II hepatotoxicity in 40 (28.6%) and grades III and IV hepatotoxicity in 12 (8.5%) patients. The association between the three polymorphisms and hepatotoxicity was evaluated using five genetic models and none of the three studied polymorphisms were significantly associated with hepatotoxicity. Discussion : The results of our study showed that AS3MT rs11191439, rs3740390, and rs3740393 polymorphisms are not associated with hepatotoxicity in APL patients. Genetic polymorphisms in enzymes which are involved in arsenic metabolism have been shown to have ethnicity and race-related differences. To more precisely characterize the association between AS3MT gene polymorphism and hepatotoxicity, future large-scale studies in non-Asian populations and other ethnicities are needed.

Keywords: Acute promyelocytic leukemia (APL); Hepatotoxicity; Polymorphism.

Figure 1A

Electrophoresis pattern of tetra-ARMS-PCR for genotyping of rs3740390. 413 bp band represents the common amplicon, whereas the C and T allele-specific bands are represented by the 272 and 196 bp amplicons, respectively (P: patient, L: 100 bp DNA ladder; NC: negative control).

Figure 1B

SNP rs3740390 direct sequencing (by the reverse primer). Representative electropherogram, heterozygote C/T. The red rectangles indicate the SNP position.

Figure 1C

Electrophoresis pattern of tetra-ARMS-PCR for genotyping of rs3740393. 437 b3p band represents the common amplicon, whereas the G and C allele-specific bands are represented by the 217 and 278 bp amplicons, respectively (P: patient, L: 100 bp DNA ladder; NC: negative control).

Figure 1D

SNP rs3740393 direct sequencing (by the forward primer). Representative electropherogram, heterozygote G/C. The green rectangles indicate the SNP position.