Effective treatment in AML remains an unsolved question. Conventional methods like Cytarabine, Daunorubicin, or Idarubicin, though effective, cause chemotherapy resistance which is a prevailing problem that brings about resistance and ultimately death. Going into a novel prognostic marker can be effective for personalized treatment in leukemia patients (6, 7). Hitherto, a considerable number of AML patients did not attain complete remission, several patients responded poorly and relapsed later. Though drug resistance remains an area of interest for researchers, further researches need to be conducted. Various methods have been developed regarding drug resistance such as drug resistance associated proteins like Multidrug resistant protein (MDR), Lung related protein (LRP), MRP 1, Breast cancer resistant protein (BCRP), etc. Some enzymes like Glutathione S-transferases (GST), Protein kinase C (PKC), etc. also play a vital role. Gene alteration plays a significant role in drug resistance (FLT3, RAS family, IDH, ASXL1). Several inhibitors are on clinical trials to restrain drug resistance (8). The contribution of efflux transporters like ABC transporters is of primary concern for drug resistance as the chemotherapeutic drug influx is imperious for successful treatment (9). Even though extensive studies have been done, the role of ABC transporters is so far not comprehensible. ABC transporters are one of the largest families of transmembrane proteins, found in every living organism and play a primary role in drug efflux, which is the most usual cause of drug resistance. Many of the ABC transporters have been investigated in various malignancies like prostate (10), neuroblastoma (11), blood malignancies (9), etc. Several researches manifested coexpression between ABC transporters. Coexpression, considered one of the poor prognostic markers, is compared with those who expresses one efflux transporter (ABC) (12–17). In our population, a small number of drug resistance transporters have been examined. From this perspective, the current research was designed to explore one of the ABC transporters, MRP 1, in AML patients. MRP 1 protein in AML patients in our population has not been investigated yet, but it was analyzed by ELISA.
Demographic analysis revealed that males are more affected than females (Fig. 3) in this study. This finding is consistent with previous studies (7, 9). As long as the age is concerned, the mean age was found to be 33.15 ± 10.63. Most of the patients were between 25 to 39 years of age (Fig. 4)This finding is in line with other studies that reported more patients were enrolled between 15 to 40 years of age (9). The reason for the predominance of young adult males in AML might be because of obesity, poor dietary habits, or occupational hazards like ionizing radiation, tobacco smoking, and people belonging to rural areas working in agriculture fields, or animal farming (18, 19). Nearly 80% of younger AML patients reached remission after induction therapy and a majority of them relapsed with resistance to the current treatment method. Even in patients treated with aggressive therapy, the 5 year survival rate is less than 35% (20–22). Some of the drug efflux transporters corresponding to age have been analyzed such as MDR1 expression. The efflux of the drug grew with age from 17% in patients less than 35 years old to 39% in patients above 50 years. In opposition to MDR1, expression of MRP 1 decreased with the age of the patients. Likewise, expression of BCRP was high in above 60 years patients (ABC/ efflux transporter) (22–24). According to the current study, the expression of MRP1 increased (70.6%) with the age between 25 to 39 years (70.6%) contrary to patients less than 25 years (27.3%).
This study found that there is a upregulation of MRP 1 gene in patients who didn’t reach remission (69.2%) as shown in (Table 1). Maria Paprocka1 et al also reported overexpression (86%) of MRP 1 in patients who didn’t reach remission (7). Though, some other studies showed that MRP 1 had no significance to anticipate treatment response, has no prognostic value, and its relationship with remission is somehow contentious (25–29). On the other hand, Antonella Maria Salvia, et al. noticed upregulation of ABCC1/ MRP1 in relapsed and no remission groups. They also asserted that failure in chemotherapeutic response can be due to MDR 1 gene (one of the ABC transporter) which was related to poor prognosis (30). There are 49 ATP-binding cassette (ABC) transporters express on multiple cells of the body and several researches have revealed the role of multidrug resistance genes in several carcinomas. One previous research concerning multidrug resistance was conducted in Russia in 2019 which presented its results about one of the multidrug resistance genes MDR 1 in primary AML patients, in which MDR 1 moderately corresponded to poor therapy response and resistance to cytarabine, and strongly corresponded to resistance with daunorubicin (31). In 2019, Huang Y et al examined ABCB1, ABCB4, ABCC1, ABCC4, and ABCG2 gene expression in 96 AML patients and found out that patients with no complete remission had a higher level of multidrug resistance protein. They also established that failure to efflux transport inhibitor therapy could be due to the existence of more than one transporter (12, 32).
Literature search suggested that acute myeloid leukemia has diverse entities observed by diverse pathophysiologic, clinical, cytogenetic, and molecular profiles that benefit from customized treatments and have different responses and results. Based upon cytogenetics and molecular profile, patients are categorized as favorable, intermediate, and unfavorable risk groups as stated earlier. FMS-like tyrosine kinase 3 (FLT3) plays a major role in cell proliferation and the survival of hematopoietic progenitor cells. It mutates frequently in AML patients accounting for 25 to 30% (33). There is a poor risk of FLT3 mutation with normal cytogenetics. NPM1 is another mutation found in AML, and it occurs in 45–64% of the AML cases. With good cytogenetics, patients with NPM1 mutation have a good prognosis, but when it coexists with FLT3/ ITD, it shows a poor prognosis (34–36). Hirsch and his co-workers investigated the relation between multiple prognostic specifications like age, FLT3, NPM1, CEBPA, and the role of ABC transporters as an autonomous prognostic factor in adult AML patients with favorable karyotyping (12, 37). With respect to previous researches, the relationship of FLT3, NPM1, and cytogenetics with our gene of interest i.e. MRP 1 in this study was analyzed.
As far as the relationship between FLT3 and MRP 1 expression is concerned, it was found that FLT3 positive patients showed overexpression of MRP1 but our results were statistically insignificant (Table 3) which is in accordance with the analysis of Salvia AM and his colleagues who reported overexpression of ABCC1/MRP1 and ABCC6 (one of the efflux transporter) in FLT3 positive AML patients (28).
Table 3
Association between FLT3 mutation and MRP 1 gene expression
MRP 1 gene | FLT3 Mutation | P-value |
Positive | Negative |
High Expression | 4 (66.7%) | 14 (43.8%) | 0.138^ |
Low Expression | 2 (33.3%) | 18 (56.3%) |
Clinically, NPM1 mutations have a significant impact on prognosis in acute myeloid leukemia patients. It has been recorded that patients with the NPM1 mutation have a favorable prognosis and notable complete remission (CR) after chemotherapy compared to non-mutated patients (38). About NPM1 mutation and MRP 1, no significant relation was found in the research Table 4 which is in line with previous studies. As far as the association between MRP 1 and karyotyping is a matter of concern, the current study didn’t find any association between them Table 5 which is in agreement with previous studies (13, 37, 38). However, some studies reported that the deletion of MRP 1 in inv (16) karyotype was connected with good outcomes in AML patients (13, 30, 39).
Table 4
Number of the patients with NPM1 mutation in association with MRP 1 gene expression
MRP 1 Gene | NPM1 | P value |
Positive | Negative |
High expression | 8 (40.0%) | 7(38.9%) | 0 .944^ |
Low expression | 12(60%) | 11 (61.1%) |
Table 5
Association between Favorable and unfavorable karyotyping with MRP 1 gene
MRP 1 Gene | Karyotyping | P value |
Favorable | Unfavorable |
High expression | 7 (46.7%) | 12 (50%) | 0 .839^ |
Low expression | 8 (53.3%) | 12 (50%) |
^ Chi square Test; P value < 0.05 considered as statistically significant
Previous researches have suggested that efflux transporters can be regarded as independent prognostic markers in addition to FLT3, NPM1 mutation, and cytogenetics (37, 40).