Selective AKR1C3 Inhibitors Potentiate Chemotherapeutic Activity in Multiple Acute Myeloid Leukemia (AML) Cell Lines

Abstract

We report the design, synthesis, and evaluation of potent and selective inhibitors of aldo-keto reductase 1C3 (AKR1C3), an important enzyme in the regulatory pathway controlling proliferation, differentiation, and apoptosis in myeloid cells. Combination treatment with the nontoxic AKR1C3 inhibitors and etoposide or daunorubicin in acute myeloid leukemia cell lines, elicits a potent adjuvant effect, potentiating the cytotoxicity of etoposide by up to 6.25-fold and the cytotoxicity of daunorubicin by >10-fold. The results validate AKR1C3 inhibition as a common adjuvant target across multiple AML subtypes. These compounds in coadministration with chemotherapeutics in clinical use enhance therapeutic index and may avail chemotherapy as a treatment option to the pediatric and geriatric population currently unable to tolerate the side effects of cancer drug regimens.

Keywords: AKR1C3 Inhibitor; acute myeloid leukemia; adjuvant; daunorubicin; etoposide; synergism.

Figure 1

Synergistic activity of AKR1C3 inhibitors with etoposide in HL-60 cells following 72 h coincubation. Values are the mean ± SD (n = 6). The two-tailed t test analysis was used to compare the statistical difference between control and treatments; ns, not significant; *p < 0.01, **p < 0.05, ***p < 0.001, ****p < 0.0001.

Scheme 1. Synthesis of para-Amide Derivative 2

Reagents and conditions: (i) Br₂, AcOH, 44%; (ii) tert-butyl acrylate, NEt₃, P(Ph)₃, Pd(OAc)₂, PhMe, reflux, 64%; (iii) 3-phenylpropanoyl chloride, NEt₃, DMAP, DCM, 70 °C, 10%; (iv) prenylboronic acid pinacol ester, Pd(dppf)Cl₂, Cs₂CO₃, DMF, 90 °C, 44%; (v) SiO₂, PhMe, reflux, 50%.

Scheme 2. Synthesis of meta-Ester Derivative 3

Reagents and conditions: (i) MeOH, H₂SO₄, reflux, 93%; ii Br₂, AcOH, RT, 35%; (iii) prenylboronic acid pinacol ester, Pd(dppf)Cl₂, Cs₂CO₃, DMF, 90 °C, 27%; (iv) NaOH, H₂O, reflux, 99%; (v) 3-phenylpropanoyl chloride, DMAP, NEt₃, DCM, RT, 82%.

Scheme 3. Synthesis of meta-Amide Derivative 4

Reagents and conditions: (i) tert-butyl acrylate, Pd(OAc)₂, P(Ph)₃, NEt₃, PhMe, 110 °C, 64%; (ii) 3-phenylpropanoyl chloride, DMAP, NEt₃, DCM, 70 °C, 88%; (iii) prenylboronlc acid pinacol ester, Pd(dppf)Cl₂, Cs₂CO₃, DMF, 90 °C, 42%; (iv) SiO₂, PhMe, reflux, 27%.

Figure 2

Synergistic activity of AKR1C3 inhibitors with etoposide in KG1a cells. Seventy-two hours of coincubation with etoposide. Values are the mean ± SD (n = 6). The two-tailed t test analysis was used to compare the statistical difference between control and treatments; ns, not significant; *p < 0.01, **p < 0.05, ***p < 0.001, ****p < 0.0001.

Figure 3

Synergistic activity of AKR1C3 inhibitors with etoposide in HL-60 cells (pretreatment). (a–d) Twenty-four hours of pretreatment of AKR1C3 inhibitor followed by 72 h exposure to etoposide. Values are the mean ± SD (n = 6). The two-tailed t test analysis was used to compare statistical difference between control and treatment; ns, not significant; **p < 0.05, ***p < 0.001, ****p < 0.0001. (e) Quantification of synergistic activity.