Development of β-Lapachone Prodrugs for Therapy Against Human Cancer Cells with Elevated NAD(P)H:Quinone Oxidoreductase 1 Levels

Abstract

B-Lapachone, an o-naphthoquinone, induces a novel caspase-and p53-independent apoptotic pathway dependent on NAD(P)H:quinone oxidoreductase1 (NQO1). NQO1reduces B-lapachone to an unstable hydroquinone that rapidly undergoes a two-step oxidation back to the parent compound, perpetuating a futile redox cycle. A deficiency or inhibition of NQO1rendered cells resistant to B-lapachone. Thus, B-lapachone has great potential for the treatment of specific cancers with elevated NQO1levels (e.g., breast, non^small cell lung, pancreatic, colon, and prostate cancers). We report the development of mono(arylimino) derivatives of B-lapachone as potential prodrugs. These derivatives are relatively nontoxic and not substrates for NQO1when initially diluted in water. In solution, however, they undergo hydrolytic conversion to B-lapachone at rates dependent on the electron-withdrawing strength of their substituent groups and pH of the diluent. NQO1enzyme assays, UV-visible spectrophotometry, high-performance liquid chromatographyelectrospray ionization-mass spectrometry, and nuclear magnetic resonance analyses confirmed and monitored conversionof each derivative to B-lapachone. Once converted, B-lapachone derivatives caused NQO1-dependent, A-calpain-mediated cell death in human cancer cells identical to that caused by B-lapachone. Interestingly, coadministration of N-acetyl-L-cysteine prevented derivative-induced cytotoxicity but did not affect B-lapachone lethality. Nuclear magnetic resonance analyses indicated that prevention of B-lapachone derivative cytotoxicity was the result of direct modification of these derivatives by N-acetyl-L-cysteine, preventing their conversion to B-lapachone. The use of B-lapachone mono(arylimino) prodrug derivatives, or more specifically a derivative converted in a tumor-specific manner (i.e., in the acidic local environment of the tumor tissue), should reduce normal tissue toxicity while eliciting tumor-selective cell killing by NQO1 bioactivation.

Antitumor Activity of Biflorin, an o-Naphthoquinone Isolated from Capraria biflora

“…15,16) In fact, the naphthoquinones, mainly represented by b-lapachone, constitutes a promising group of compounds with antitumor properties. [17][18][19][20]21) Lima et al (1972) had studied the antitumor activity of naphthoquinones, e.g. juglone, lapachol, lawsone and plumbagine, on the same experimental models as the present paper, showing that these compounds, with the exception of lapachol, were able to inhibit the sarcoma 180 tumor growth.…”

“…12,20,28) In fact, the mechanisms of cell death triggered by b-lapachone remains controversial. 18) Despite the induction of oxidative stress, b-lapachone inhibited the catalytic activity of topoisomerase I 29) and selectively induced apoptosis in transformed cells but not in proliferating normal cells.…”

β-lapachone Activates a Mre11p-Tel1p G1/S Checkpoint in Budding Yeast

“…24 Reduction of β-lapachone by NQO1 leads to a futile cycling between the quinone and hydroquinone forms, with a concomitant loss of reduced NAD(P)H that ultimately induces cell death. Consistent with this mechanism (1) dicoumarol, an inhibitor of NQO1, inhibited lethality and cell death triggered by the drug, 24 (2) a prodrug of β-lapachone was nonlethal to cells until the drug was converted to β-lapachone by NQO1, 32 and (3) cell death by β-lapachone was calcium and calpain dependent, all being activated by NQO1 and inhibited by dicoumarol. 33 In addition, reduction of β-lapachone by NQO1 was proposed to be unstable and spontaneously revert to the parental compound, creating a back reaction that would cause generation of radical oxygen species (ROS).…”

Reduction of doxorubicin-induced genotoxicity by Handroanthus impetiginosus in mouse bone marrow revealed by micronucleus assay

“…β-lapachone (3,4-dihydro-2,2-dimethyl-2H-naphthol[1,2-b] pyran-5,6-dione, ARQ 501), a natural o-naphthoquinone and a major component in an ethanol extract of H. impetiginosus bark, displayed promising antitumor activity in various tumor cells (Pardee et al, 2002;Tagliarino et al, 2003;Terai et al, 2009;Tan et al, 2012) and has been tested as an antitumor drug in phase I, II, and III clinical trials in combination with other chemotherapeutic agents (Pardee et al, 2002;Bentle et al, 2007). The anticancer activity of β-lapachone may involve its catalysis by NAD(P) H:quinone oxidoreductase (NQO1, DT-diaphorase), which used NAD(P)H or NADH as an electron source to yield the two-electron reduction of β-lapachone (Pardee et al, 2002;Reinicke et al, 2005). In the presence of NQO1, β-lapachone underwent reduction to an unstable hydroquinone, resulting in the generation of ROS, including superoxides (Pink et al, 2000;De Witte et al, 2004;Choi et al, 2007).…”

“…The expression of NQO1 in solid cancers is higher than in normal tissues (Belinsky and Jaiswal., 1993), including in carcinoma of the liver (Schlager and Powis, 1990), colon (Smitskamp-Wilms et al, 1995), breast (Schlager and Powis, 1990;Smitskamp-Wilms et al, 1995), brain (Berger et al, 1985), and lung (Schlager and Powis, 1990). In addition, NQO1 has been shown to be an important factor in β-lapachone-induced cell death in many kinds of cancer cells (Pink et al, 2000;Reinicke et al, 2005), including breast cancer (Tagliarino et al, 2003), glioma (Park et al, 2011), and prostate cancer (Pink et al, 2000). In this context, other methods have been examined to increase NQO1 expression or activity in cancer cells (Terai et al, 2009;Tan et al, 2012;Satsu et al, 2012) in order to increase the clinical efficacy of β-lapachone.…”