RESUMEN
Pentavalent antimonials are the first line drugs for the treatment of leishmaniasis. Unresponsiveness of Leishmania spp. to antimonial drugs is a serious problem in some endemic areas. Investigations on molecular mechanisms involved in drug resistance are essential for monitoring and managing of the disease. Cal-cineurin is an essential protein phosphatase for number of signal transduction pathways in eukaryotic cells and it has a mediated role in apoptosis. This study aimed to determine of biomarker[s] in Glucantime[registered sign] resiatance strain of L. infan-tum. We used cDNA amplified fragment length polymorphism [cDNA-AFLP] and real time-RT PCR assays to compare gene expression profiles at the mRNA levels in resistant and susceptible L. infantum field isolates. The cDNA-AFLP results showed downlegulation of calcineurin in resis-tant isolate in comparison with susceptible one. Significant downregulation of cal-cineurin [0.42 fold] [P<0.05] was found in resistant isolate compared to susceptible one by Real time-RT PCR. This is the first report of calcineurin implication in Glucantime[registered sign] drug resistance of field [natural] isolate of L. infantum. Downregulation of calcineurin could protect parasites from antimonial-induced apoptosis
RESUMEN
The mainstay therapy against leishmaniasis is still pentavalent antimonial drugs; however, the rate of antimony resistance is increasing in endemic regions such as Iran. Understanding the molecular basis of resistance to antimonials could be helpful to improve treatment strategies. This study aimed to recognize genes involved in antimony resistance of Leishmania tropica field isolates. Sensitive and resistant L. tropica parasites were isolated from anthroponotic cutaneous leishmaniasis patients and drug susceptibility of parasites to meglumine antimoniate (Glucantime(R)) was confirmed using in vitro assay. Then, complementary DNA-amplified fragment length polymorphism (cDNA-AFLP) and real-time reverse transcriptase-PCR (RT-PCR) approaches were utilized on mRNAs from resistant and sensitive L. tropica isolates. We identified 2 known genes, ubiquitin implicated in protein degradation and amino acid permease (AAP3) involved in arginine uptake. Also, we identified 1 gene encoding hypothetical protein. Real-time RT-PCR revealed a significant upregulation of ubiquitin (2.54-fold), and AAP3 (2.86-fold) (P<0.05) in a resistant isolate compared to a sensitive one. Our results suggest that overexpression of ubiquitin and AAP3 could potentially implicated in natural antimony resistance.