Antitumor Effects and Delivery Profiles of Menahydroquinone-4 Prodrugs with Ionic or Nonionic Promoiety to Hepatocellular Carcinoma Cells

Abstract

Hepatocellular carcinoma (HCC) shows poor prognosis owing to its very frequent recurrence even after curative treatment. Thus, an effective and safe long-term chemopreventive agent is strongly in demand. Menahydroquinone-4 (MKH) is an active form of menaquinone-4 (MK-4, vitamin K2) that is involved in the synthesis of vitamin K-dependent proteins in the liver. We hypothesized that efficient delivery of MKH might be critical to regulate HCC proliferation. The discovery of a suitable prodrug targeting HCC in terms of delivery and activation could reduce the clinical dose of MK-4 and maximize efficacy and safety. We previously showed that MKH dimethylglycinate (MKH-DMG) enables effective delivery of MKH into HCC cells and exhibits strong antitumor effects compared with MK-4. In this study, we prepared anionic MKH hemi-succinate (MKH-SUC) and non-ionic MKH acetate (MKH-ACT), in addition to cationic MKH-DMG, and evaluated MKH delivery profiles and antitumor effects in vitro. MKH-SUC showed the highest uptake and the most efficient release of MKH among the examined compounds and exhibited rapid and strong antitumor effects. These results indicate that MKH-SUC might have a good potential as an MKH delivery system for HCC that overcomes the limitations of MK-4 as a clinical chemopreventive agent.

Prodrugs for Skin Delivery of Menahydroquinone-4, an Active Form of Vitamin K2(20), Could Overcome the Photoinstability and Phototoxicity of Vitamin K2(20)

“…MKH delivery with MKH-SUC into HaCaT cells is faster than that with MKH-DMG. A similar result was obtained while using hepatocellular carcinoma (HCC) cells in a previous study—the uptake and reconversion rates of MKH-SUC in HCC cells were faster than those of MKH-DMG [17]. Therefore, it can be presumed that the rapid and increased MKH delivery with MKH-SUC in HaCaT cells is due to the rapid uptake and fast reconversion rates.…”

“…Our results clearly show that MKH derivatives and MK-4 increase intracellular MKO levels in the keratinocyte cell line we used, indicating that they could be used to deliver MKH into keratinocytes, where it then acts as a cofactor for GGCX. We previously showed that MKH-DMG and MKH-SUC reconvert to MKH in a reaction catalyzed by carboxyl esterase [17], which is present in dermal cells [19,20,21], so accelerated intracellular reconversion to a parent drug is possible. Although UVA-irradiated MK-4 did not increase intracellular MKO, UVA-irradiated MKH derivatives were able to.…”

“…Menaquinone-4 epoxide (MKO) was kindly provided by Eisai Co., Ltd. (Tokyo, Japan). Menahydroquinone-4 1,4-bis- N , N -dimethylglycinate hydrochloride (MKH-DMG) and menahydroquinone-4 1,4-bis-hemisuccinate (MKH-SUC) were synthesized in our laboratory using previously reported methods [17]. Other chemicals were purchased from FUJIFILM Wako Pure Chemical Corporation (Osaka, Japan).…”

“…It has been shown that the main photodegradation product of MK-4 is MK-4 chromenol (MKC), which is produced from the naphthoquinone structure and isoprenyl side chain of MK-4. We have previously reported that ester-type prodrugs of MKH, such as the 1,4-bis- N , N -dimethylglycinate (MKH-DMG) and hemi-succinate (MKH-SUC) derivatives, can act as delivery systems for MKH without a reductive activation step [14,15,16,17]. Since these compounds do not contain the naphthoquinone structure, these prodrugs may overcome the photoinstability and phototoxicity problems.…”

“…It has been reported that the partition coefficient (log P) of MKH-DMG at physiological pH 7.4 is 3.66 [14]; this value indicates that MKH-DMG has good lipophilicity for membrane permeation. In addition, MKH-DMG and MKH-SUC could deliver MKH into hepatocellular carcinoma (HCC) cells more effectively than MK-4 [17]. Thus, MKH-DMG and MKH-SUC were considered to be good candidate compounds for skin application.…”