A Novel Drug Modulator Diarylheptanoid (trans-1,7-Diphenyl-5-hydroxy-1-heptene) from Curcuma comosa Rhizomes for P-glycoprotein Function and Apoptosis Induction in K652/ADR Leukemic Cells

Curcuma comosa has been used in traditional Thai medicine to treat menstrual cycle-related symptoms in women. This study aims to evaluate the diarylheptanoid drug modulator, trans-1,7-diphenyl-5-hydroxy-1-heptene (DHH), in drug-resistant K562/ADR human leukemic cells. This compound was studied due to its effects on cell cytotoxicity, multidrug resistance (MDR) phenotype, P-glycoprotein (P-gp) expression, and P-gp function. We show that DHH itself is cytotoxic towards K562/ADR cells. However, DHH did not impact P-gp expression. The impact of DHH on the MDR phenotype in the K562/ADR cells was determined by co-treatment of cells with doxorubicin (Dox) and DHH using an MTT assay. The results showed that the DHH changed the MDR phenotype in the K562/ADR cells by decreasing the IC₅₀ of Dox from 51.6 to 18.2 µM. Treating the cells with a nontoxic dose of DHH increased their sensitivity to Dox in P-gp expressing drug-resistant cells. The kinetics of P-gp mediated efflux of pirarubicin (THP) was used to monitor the P-gp function. DHH was shown to suppress THP efflux and resulted in enhanced apoptosis in the K562/ADR cells. These results demonstrate that DHH is a novel drug modulator of P-gp function and induces drug accumulation in the Dox-resistant K562 leukemic cell line.

The role of the multi-drug resistance 1, p53, b cell lymphoma 2, and bcl 2-associated X genes in the biologic behavior and chemotherapeutic resistance of canine transmissible venereal tumors

BACKGROUND

Canine transmissible venereal tumors (CTVTs) generally have different cytomorphologic subtypes and phases of progression. Some tumors have variable biologic behavior including a progressive increase in tumor aggressiveness and variable responses to chemotherapy. This behavior is partially due to high p-glycoprotein expression by tumor cells, which leads to the expulsion of chemotherapeutic drugs. Other possible causes include changes in pro- and anti-apoptotic genes from the BCL-2 family and DNA repair systems, which are associated with the p53 gene family.

OBJECTIVES

We aimed to determine the relative expression of the multi-drug resistance 1 (MDR1), p53, b-cell lymphoma 2 (BCL2), and bcl 2-associated X (BAX) genes in CTVT before and after therapy and establish a relationship with treatment responses, cytomorphologic patterns, and tumor progression identified with histopathology.

METHODS

RT-qPCR was performed on 21 CTVT tumor samples before and after initiating chemotherapy to determine specific gene expression. Normal canine testicular tissue was used as a negative control for all experiments.

RESULTS

MDR1 expression was decreased before and after initiating vincristine therapy in CTVT tumor tissues compared with normal canine testicular tissue; p53 and BAX were overexpressed at both time points compared with normal tissue, and no statistical differences were seen between the different morphologic types. However, BAX expression was decreased in the group with quick therapeutic responses but was still overexpressed compared with normal testicular tissue. In the group with the slowest chemotherapeutic responses, BCL2 was overexpressed.

CONCLUSION

The findings of this study showed a relative increase in MDR1 gene expression in response to chemotherapy and higher expression in plasmacytoid CTVTs compared with the other cytomorphologic patterns. BCL2 overexpression was related to a favorable prognosis, and p53, BAX, and BCL2 were expressed independent of the cytomorphologic CTVT type. All of the genes were expressed independent of tumor progression, as noted on histopathology.

Mechanisms of drug resistance in acute myeloid leukemia

Acute myeloid leukemia (AML) is a kind of malignant hematopoietic system disease characterized by abnormal proliferation, poor cell differentiation, and infiltration of bone marrow, peripheral blood, or other tissues. To date, the first-line treatment of AML is still based on daunorubicin and cytosine arabinoside or idarubicin and cytosine arabinoside regimen. However, the complete remission rate of AML is still not optimistic, especially in elderly patients, and the recurrence rate after complete remission is still high. The resistance of leukemia cells to chemotherapy drugs becomes the main obstacle in the treatment of AML. At present, the research on the mechanisms of drug resistance in AML is very active. This article will elaborate on the main mechanisms of drug resistance currently being studied, including drug resistance-related proteins and enzymes, gene alterations, micro RNAs, and signal pathways.

Low MDR1 and BAALC expression identifies a new subgroup of intermediate cytogenetic risk acute myeloid leukemia with a favorable outcome

Treatment optimization in acute myeloid leukemia requires the accurate assignment of patients at diagnosis to specific risk groups to guide subsequent risk-adapted treatment stratification. In this study, we have evaluated the impact of expression of the gene BAALC in conjunction with MDR1 in AML with intermediate cytogenetic risk group to more precisely define risk assessment. Low MDR1/high BAALC, high MDR1/low BAALC, and high MDR1/high BAALC expressers demonstrated a similar clinical outcome with CR rate being 68.75-75% and relapse rate being 40-50% and therefore could be considered as a "combined group". In contrast, low expression of both BAALC and MDR1 identifies an intermediate cytogenetic risk group a distinctly favorable outcome, with higher CR rate being 93.3%, lower relapse rate being 7.1%, and longer OS being 50.3% than that of the "combined group". Moreover, low MDR1/low BAALC expressers in the intermediate cytogenetic risk group also demonstrated a comparable clinical outcome with patients in the favorable-risk group. Thus low MDR1/low BAALC expression identifies a subgroup of intermediate cytogenetic risk AML patients with a remarkably good long-term outcome achieved by chemotherapy alone.

Idarubicin is superior to daunorubicin in remission induction of de novo acute myeloid leukemia patients with high MDR1 expression

Aim: To investigate whether idarubicin in a cytarabine-based induction regimen was superior to daunorubicin in de novo acute myeloid leukemia patients expressing high MDR1. Patients & methods: The clinicopathological data were analyzed in 125 patients receiving daunorubicin or idarubicin with cytarabine for remission induction. Median MDR1 mRNA expression in pretreated bone marrow cells was used as the cutoff point for high and low MDR1 expression. Results: A total of 59.7% high and 77.8% low MDR1 expressers achieved complete remission (CR; p = 0.029). Idarubicin yielded a higher CR rate than daunorubicin in high MDR1 expressers (82.1 vs 41.2%; p = 0.001), it also demonstrated a higher CR rate than daunorubicin (p < 0.05) in high MDR1 expressers exhibiting favorable or intermediate risk, while there was no difference between the two treatment arms in low MDR1 expressers exhibiting either favorable or intermediate risk. Conclusion: Idarubicin is associated with better remission induction of de novo acute myeloid leukemia patients with high MDR1 expression.

Original submitted 23 May 2012; Revision submitted 10 October 2012