Age and dietary form of vitamin K affect menaquinone-4 concentrations in male Fischer 344 rats

Vitamin K2 sensitizes the efficacy of venetoclax in acute myeloid leukemia by targeting the NOXA-MCL-1 pathway

Promising outcomes have been reported in elder patients with acute myeloid leukemia (AML) using combined therapy of venetoclax (VEN) and azacytidine (AZA) in recent years. However, approximately one-third of patients appear to be refractory to this therapy. Vitamin K2 (VK2) shows apoptosis-inducing activity in AML cells, and daily oral VK2 (menaquinone-4, GlakayR) has been approved for patients with osteoporosis in Japan. We observed a high response rate to AZA plus VEN therapy, with no 8-week mortality in the newly diagnosed AML patients consuming daily VK2 in our hospital. The median age of the patients was 75.9 years (range 66-84) with high-risk features. Patients received AZA 75 mg/m2 on D1-7, VEN 400 mg on D1-28, and daily VK2 45 mg. The CR/CRi ratio was 94.7% (18/19), with a CR rate of 79%. Complete cytogenetic CR was achieved in 15 of 19 (79%) patients, and MRD negativity in 2 of 15 (13%) evaluable CR patients. Owing to the extremely high response rate in clinical settings, we further attempted to investigate the underlying mechanisms. The combination of VK2 and VEN synergistically induced apoptosis in all five AML cell lines tested. VK2, but not VEN, induced mitochondrial reactive oxygen species (ROS), leading to the transcriptional upregulation of NOXA, followed by MCL-1 repression. ROS scavengers repressed VK2 induced-NOXA expression and led to the cancellation of pronounced apoptosis and the downregulation of MCL-1 by VK2 plus VEN. Additionally, knockdown and knockout of NOXA resulted in abrogation of the MCL-1 repression as well as enhanced cytotoxicity by the two-drug combination, indicating that VK2 suppresses MCL-1 via ROS-mediated NOXA induction. These data suggest that the dual inhibition of BCL-2 by VEN and MCL-1 by VK2 is responsible for the remarkable clinical outcomes in our patients. Therefore, large-scale clinical trials are required.

Enhanced ER-associated degradation of HMG CoA reductase causes embryonic lethality associated with Ubiad1 deficiency

UbiA prenyltransferase domain-containing protein-1 (UBIAD1) synthesizes the vitamin K subtype menaquinone-4 (MK-4). Previous studies in cultured cells (Schumacher et al., 2015) revealed that UBIAD1 also inhibits endoplasmic reticulum (ER)-associated degradation (ERAD) of ubiquitinated HMG CoA reductase (HMGCR), the rate-limiting enzyme of the mevalonate pathway that produces cholesterol and essential nonsterol isoprenoids. Gene knockout studies were previously attempted to explore the function of UBIAD1 in mice; however, homozygous germ-line elimination of the Ubiad1 gene caused embryonic lethality. We now report that homozygous deletion of Ubiad1 is produced in knockin mice expressing ubiquitination/ERAD-resistant HMGCR. Thus, embryonic lethality of Ubiad1 deficiency results from depletion of mevalonate-derived products owing to enhanced ERAD of HMGCR rather than from reduced synthesis of MK-4. These findings provide genetic evidence for the significance of UBIAD1 in regulation of cholesterol synthesis and offer the opportunity in future studies for the discovery of new physiological roles of MK-4.

Establishment of the Variation of Vitamin K Status According to Vkorc1 Point Mutations Using Rat Models

Vitamin K is crucial for many physiological processes such as coagulation, energy metabolism, and arterial calcification prevention due to its involvement in the activation of several vitamin K-dependent proteins. During this activation, vitamin K is converted into vitamin K epoxide, which must be re-reduced by the VKORC1 enzyme. Various VKORC1 mutations have been described in humans. While these mutations have been widely associated with anticoagulant resistance, their association with a modification of vitamin K status due to a modification of the enzyme efficiency has never been considered. Using animal models with different Vkorc1 mutations receiving a standard diet or a menadione-deficient diet, we investigated this association by measuring different markers of the vitamin K status. Each mutation dramatically affected vitamin K recycling efficiency. This decrease in recycling was associated with a significant alteration of the vitamin K status, even when animals were fed a menadione-enriched diet suggesting a loss of vitamin K from the cycle due to the presence of the Vkorc1 mutation. This change in vitamin K status resulted in clinical modifications in mutated rats only when animals receive a limited vitamin K intake totally consistent with the capacity of each strain to recycle vitamin K.

Divergent effects of vitamins K1 and K2 on triple negative breast cancer cells

Vitamin K serves as an essential co-factor in the γ-carboxylation of glutamate to γ-carboxyglutamate (GLA), a post-translational modification mediated by gamma-glutamyl carboxylase (GGCX) and vitamin K oxidoreductases (VKORC1 or VKORC1L1). While both phylloquinone (K1) and menaquinone (K2) support the synthesis of GLA-modified proteins, studies assessing K1 and/or K2 effects in cancer cells have reported minimal effects of K1 and anti-proliferative or pro-apoptotic effects of K2. qPCR results indicated highest expression of GGCX, VKORC1, and VKORC1L1 in triple negative breast cancer (TNBC) cell lines, Hs578T, MDA-MB-231 and SUM159PT, and in advanced stage disease. To assess differential effects of vitamin K, TNBC cells were cultured in media supplemented with K1 or K2. K1 treatment increased cell growth, and enhanced stemness and GLA-modified protein expression in TNBC lysates. Alternatively, lysates from cells exposed to vehicle, K2, or the VKOR antagonist, warfarin, did not express GLA-modified proteins. Further, K2 exposure reduced stemness and elicited anti-proliferative effects. These studies show that TNBC cells express a functional vitamin K pathway and that K1 and K2 exert distinct phenotypic effects. Clarification of the mechanisms by which K1 and K2 induce these effects may lead to relevant therapeutic strategies for manipulating this pathway in TNBC patients.

Missense mutation of VKORC1 leads to medial arterial calcification in rats

Vitamin K plays a crucial role in the regulation of vascular calcifications by allowing activation of matrix Gla protein. The dietary requirement for vitamin K is low because of an efficient recycling of vitamin K by vitamin K epoxide reductase (VKORC1). However, decreased VKORC1 activity may result in vascular calcification. More than 30 coding mutations of VKORC1 have been described. While these mutations have been suspected of causing anticoagulant resistance, their association with an increase in the risk of vascular calcification has never been considered. We thus investigated functional cardiovascular characteristics in a rat model mutated in VKORC1. This study revealed that limited intake in vitamin K in mutated rat induced massive calcified areas in the media of arteries of lung, aortic arch, kidneys and testis. Development of calcifications could be inhibited by vitamin K supplementation. In calcified areas, inactive Matrix Gla protein expression increased, while corresponding mRNA expression was not modified. Mutation in VKORC1 associated with a limited vitamin K intake is thus a major risk for cardiovascular disease. Our model is the first non-invasive rat model that shows spontaneous medial calcifications and would be useful for studying physiological function of vitamin K.

The Vitamin K Metabolome in Chronic Kidney Disease

The purpose of this review is to summarize the research to date on the impact of chronic kidney disease (CKD) on the vitamin K metabolome. Vitamin K-dependent proteins contribute to cardiovascular disease (CVD) prevention via the prevention of ectopic mineralization. Sub-clinical vitamin K deficiency is common in CKD patients, and evidence suggests that it may contribute to the CVD burden in this population. Research from animal models suggests that CKD alters tissue measures of the two predominant forms of vitamin K: KI and MK-4. The expression and/or activity of enzymes that regulate the recycling of vitamin K and the carboxylation of vitamin K-dependent proteins also appear to be altered in CKD. Evidence suggests that statins, a common pharmaceutical prescribed to CKD patients to prevent cardiovascular events, may impact the metabolism of vitamin K and therefore contribute to its relative inefficiency at preventing CVD in this population as kidney disease progresses. Human research on the tissue vitamin K metabolome in CKD patients is lacking.

US Pharmacopeial Convention safety evaluation of menaquinone-7, a form of vitamin K

Vitamin K plays important biological roles in maintaining normal blood coagulation, bone mineralization, soft tissue physiology, and neurological development. Menaquinone-7 is a form of vitamin K2 that occurs naturally in some animal-derived and fermented foods. It is also available as an ingredient of dietary supplements. Menaquinone-7 has greater bioavailability than other forms of vitamin K, which has led to increasing sales and use of menaquinone-7 supplements. This special article reviews the chemistry, nomenclature, dietary sources, intake levels, and pharmacokinetics of menaquinones, along with the nonclinical toxicity data available and the data on clinical outcomes related to safety (adverse events). In conclusion, the data reviewed indicate that menaquinone-7, when ingested as a dietary supplement, is not associated with any serious risk to health or with other public health concerns. On the basis of this conclusion, US Pharmacopeia monographs have been developed to establish quality standards for menaquinone-7 as a dietary ingredient and as a dietary supplement in various dosage forms.

Tissue Concentrations of Vitamin K and Expression of Key Enzymes of Vitamin K Metabolism Are Influenced by Sex and Diet but Not Housing in C57Bl6 Mice

BACKGROUND

There has been limited characterization of biological variables that impact vitamin K metabolism. This gap in knowledge can limit the translation of data obtained from preclinical animal studies to future human studies.

OBJECTIVE

The purpose of this study was to determine the effects of diet, sex, and housing on serum, tissue, and fecal vitamin K concentrations and gene expression in C57BL6 mice during dietary vitamin K manipulation.

METHODS

C57BL6 4-mo-old male and female mice were randomly assigned to conventional or suspended-wire cages and fed control [1400 ± 80 μg phylloquinone (PK)/kg] or deficient (31 ± 0.45 μg PK/kg) diets for 28 d in a factorial design. PK and menaquinone (MK) 4 plasma and tissue concentrations were measured by HPLC. Long-chain MKs were measured in all matrices by LC-atmospheric pressure chemical ionization-mass spectrometry. Gene expression was quantified by reverse transcriptase-polymerase chain reaction in the liver, brain, kidney, pancreas, and adipose tissue.

RESULTS

Male and female mice responded differently to dietary manipulation in a tissue-dependent manner. In mice fed the control diet, females had ∼3-fold more MK4 in the brain and mesenteric adipose tissue than did males and 100% greater PK concentrations in the liver, kidney, and mesenteric adipose tissue than did males. In mice fed the deficient diet, kidney MK4 concentrations were ∼4-fold greater in females than in males, and there were no differences in other tissues. Males and females differed in the expression of vitamin K expoxide reductase complex 1 (Vkorc1) in mesenteric adipose tissue and the pancreas and ubiA domain-containing protein 1 (Ubiad1) in the kidney and brain. There was no effect of housing on serum, tissue, or fecal concentrations of any vitamin K form.

CONCLUSIONS

Vitamin K concentrations and expression of key metabolic enzymes differ between male and female mice and in response to the dietary PK concentration. Identifying factors that may impact study design and outcomes of interest is critical to optimize study parameters examining vitamin K metabolism in animal models.

Phylloquinone and Menaquinone-4 Tissue Distribution at Different Life Stages in Male and Female Sprague-Dawley Rats Fed Different VK Levels Since Weaning or Subjected to a 40% Calorie Restriction since Adulthood

Whether through the vitamin K-dependent proteins or the individual K vitamers, vitamin K (VK) is associated with a number of age-related conditions (e.g., osteoporosis, atherosclerosis, insulin resistance, cognitive decline). In light of this, we investigated the influence of lifetime dietary VK exposure on the tissue distribution of phylloquinone (K₁) and menaquinone-4 (MK-4) vitamers in 3-, 12- and 22-month-old male and female rats fed different K₁ diets since weaning or subjected to a 40% calorie restricted diet (CR) since adulthood. Dietary K₁ intakes around the minimal amount required for normal blood coagulation had no significant influence on body weights of both male and female rats at different life stages. Tissue contents of the K vitamers differed according to organs, were generally higher in females than in males, and increased with K₁ intake. The MK-4/total VK ratios tended to be increased in old age possibly reflecting an increased physiological demand for MK-4 during aging. Our study also confirmed the greater susceptibility of male rats to low VK containing diet, notably at a younger age. Despite lifelong higher K₁ intakes per unit body weight, tissue K₁ and MK-4 contents at 20 months were generally lower in CR rats compared to their ad libitum (AL) counterparts. Whether the lower tissue MK-4 content is the result of lower synthesis from K₁ or greater tissue utilization remains to be determined. However, the more youthful coagulation profile observed in old CR rats (vs. AL rats) tends to support the notion that CR is associated with greater utilization of the K vitamers to sustain physiological functions.

Canola and hydrogenated soybean oils accelerate ectopic bone formation induced by implantation of bone morphogenetic protein in mice

Canola oil (Can) and hydrogenated soybean oil (H2-Soy) are commonly used edible oils. However, in contrast to soybean oil (Soy), they shorten the survival of stroke-prone spontaneously hypertensive (SHRSP) rats. It has been proposed that the adverse effects of these oils on the kidney and testis are caused at least in part by dihydro-vitamin K (VK) 1 in H2-Soy and unidentified component(s) in Can. Increased intake of dihydro-VK1 is associated with decreased tissue VK2 levels and bone mineral density in rats and humans, respectively. The aim of the present study was to determine the effects of these oils on bone morphogenetic protein (BMP)-induced ectopic bone formation, which is promoted by VK2 deficiency, in relation to the role of VK in the γ-carboxylation of osteocalcin and matrix Gla protein. A crude extract of BMPs was implanted into a gap in the fascia of the femoral muscle in 5-week-old mice maintained on a Soy, Can, or H2-Soy diet. Newly formed bone volume, assessed by three-dimensional X-ray micro-computed tomography and three-dimensional reconstruction imaging for bone, was 4-fold greater in the Can and H2-Soy groups than in the Soy group. The plasma carboxylated osteocalcin (Gla-OC) and total OC (Gla-OC plus undercarboxylated osteocalcin [Glu-OC]) levels were significantly lower in the Can group than in the Soy group (p < 0.05). However, these levels did not significantly differ between the H2-Soy and Soy groups. The plasma Gla-OC/Glu-OC ratio in the Can and H2-Soy groups was significantly lower (in Can; p = 0.044) or was almost significantly lower (in H2-Soy; p = 0.053) than that in the Soy group. In conclusion, Can and H2-Soy accelerated BMP-induced bone formation in mice to a greater extent than Soy. Further research is required to evaluate whether the difference in accelerated ectopic bone formation is associated with altered levels of VK2 and VK-dependent protein(s) among the three dietary groups.

Dietary vitamin K and therapeutic warfarin alter the susceptibility to vascular calcification in experimental chronic kidney disease

The leading cause of death in patients with chronic kidney disease (CKD) is cardiovascular disease, with vascular calcification being a key modifier of disease progression. A local regulator of vascular calcification is vitamin K. This γ-glutamyl carboxylase substrate is an essential cofactor in the activation of several extracellular matrix proteins that inhibit calcification. Warfarin, a common therapy in dialysis patients, inhibits the recycling of vitamin K and thereby decreases the inhibitory activity of these proteins. In this study, we sought to determine whether modifying vitamin K status, either by increasing dietary vitamin K intake or by antagonism with therapeutic doses of warfarin, could alter the development of vascular calcification in male Sprague-Dawley rats with adenine-induced CKD. Treatment of CKD rats with warfarin markedly increased pulse pressure and pulse wave velocity, as well as significantly increased calcium concentrations in the thoracic aorta (3-fold), abdominal aorta (8-fold), renal artery (4-fold), and carotid artery (20-fold). In contrast, treatment with high dietary vitamin K1 increased vitamin K tissue concentrations (10-300-fold) and blunted the development of vascular calcification. Thus, vitamin K has an important role in modifying mechanisms linked to the susceptibility of arteries to calcify in an experimental model of CKD.

Deuterium-labeled phylloquinone has tissue-specific conversion to menaquinone-4 among Fischer 344 male rats

Phylloquinone (PK) is converted into menaquinone-4 (MK-4) via side chain removal-addition. Stable isotope use is an effective approach to identify the tissue location of this conversion, which is currently unknown. Following a 14-d PK-deficient diet, male Fischer 344 rats (8 mo; n = 15) were fed 1.6 mg deuterium-labeled PK (L-PK) per kg diet for 0 (control), 1 d (PK-1d), and 7 d (PK-7d). Both L-PK and deuterium-labeled MK-4 (L-MK-4) were detected in tissues in PK-1d and PK-7d, although the results varied. Whereas some tissues had an overall increase in MK-4 in response to L-PK, total brain, testes, and fat MK-4 concentrations did not. In contrast, L-MK-4 concentrations increased in all 3 tissues. The deuterium label was found only on the L-MK-4 naphthoquinone ring, confirming the need for side chain removal for the formation of MK-4. Labeled menadione (MD) was detected in urine and serum in PK-1d and PK-7d, confirming its role as an intermediate. A Caco-2 cell monolayer model was used to study the role of the enterocytes in the conversion process. Neither MK-4 nor MD was detected in Caco-2 cells treated with PK. However, when Caco-2 cells were treated with MD, MK-4 was formed. Similarly, MK-4 was formed in response to MD-treated 293T kidney cells, but not HuH7 liver cells. These data demonstrate that MK-4 is the predominant form of vitamin K in multiple tissues, but there appears to be a tissue-specific regulation for the conversion of PK to MK-4.

Vitamin K supplementation does not prevent bone loss in ovariectomized Norway rats

Background

Despite plausible biological mechanisms, the differential abilities of phylloquinone (PK) and menaquinones (MKn) to prevent bone loss remain controversial. The objective of the current study was to compare the effects of PK, menaquinone-4 (MK-4) and menaquinone-7 (MK-7) on the rate of bone loss in ovariectomized (OVX) Norway rats. A secondary aim was to compare the effects of vitamin K with those of bisphosphonates (BP) on bone loss.

Methods

Rats (n = 96) were randomized to 6 dosing groups [n = 16/group; Sham; OVX; OVX + BP (100 μg/kg/100 μg/mL saline sc); OVX + PK; OVX + MK-4; and OVX + MK-7] for 6 wk. Equimolar daily doses of 107 mg PK/kg, 147 mg MK-4/kg, and 201 mg MK-7/kg diet were provided.

Results

BP significantly increased bone strength and bone mineral density (BMD) vs. OVX (P < 0.05). However, PK, MK-4 or MK-7 did not change bone strength or BMD compared to the OVX group. Whereas supplementation of PK, MK-4 and MK-7 increased serum and tibia concentrations of each respective form, PK concentrations were consistently higher despite equimolar intakes.

Conclusion

PK, MK-4, and MK-7 do not appear to prevent bone loss in OVX rats when administered concurrent with adequate intake of other nutrients.

Age- and brain region-specific effects of dietary vitamin K on myelin sulfatides

Dysregulation of myelin sulfatides is a risk factor for cognitive decline with age. Vitamin K is present in high concentrations in the brain and has been implicated in the regulation of sulfatide metabolism. Our objective was to investigate the age-related interrelation between dietary vitamin K and sulfatides in myelin fractions isolated from the brain regions of Fischer 344 male rats fed one of two dietary forms of vitamin K: phylloquinone or its hydrogenated form, 2',3'-dihydrophylloquinone (dK), for 28 days. Both dietary forms of vitamin K were converted to menaquinone-4 (MK-4) in the brain. The efficiency of dietary dK conversion to MK-4 compared to dietary phylloquinone was lower in the striatum and cortex, and was similar to that in the hippocampus. There were significant positive correlations between sulfatides and MK-4 in the hippocampus (phylloquinone-supplemented diet, 12 and 24 months; dK-supplemented diet, 12 months) and cortex (phylloquinone-supplemented diet, 12 and 24 months). No significant correlations were observed in the striatum. Furthermore, sulfatides in the hippocampus were significantly positively correlated with MK-4 in serum. This is the first attempt to establish and characterize a novel animal model that exploits the inability of dietary dK to convert to brain MK-4 to study the dietary effects of vitamin K on brain sulfatide in brain regions controlling motor and cognitive functions. Our findings suggest that this animal model may be useful for investigation of the effect of the dietary vitamin K on sulfatide metabolism, myelin structure and behavior functions.

9-Cis retinoic acid reduces 1alpha,25-dihydroxycholecalciferol-induced renal calcification by altering vitamin K-dependent gamma-carboxylation of matrix gamma-carboxyglutamic acid protein in A/J male mice

Matrix gamma-carboxyglutamic acid protein (MGP), a vitamin K-dependent protein, is involved in regulation of tissue calcification. We previously reported that 9-cis retinoic acid (RA) mitigates 1alpha,25-dihydroxycholecalciferol [1,25(OH)(2)D3]-induced renal calcification in a 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK)-induced lung cancer A/J male mouse model. This raised the question if the mechanism(s) underlying this calcification involves vitamin K. We assessed expression and vitamin K dependent gamma-carboxylation of MGP and vitamin K concentrations [phylloquinone (PK), as well as its conversion product, menaquinone-4 (MK-4)] in tissues obtained from NNK-injected A/J male mice fed 1,25(OH)(2)D3 (2.5 microg/kg diet; D group) +/- RA (15 mg/kg diet) for 20 wk. Renal calcification was only observed in the D group (2/10; 20% of the group). Renal MGP mRNA and uncarboxylated MGP (ucMGP) increased in response to D (P < 0.05) but not in response to RA or RA + D. In contrast, gamma-carboxylated MGP increased to 2.2-fold of the control in response to D+RA (P < 0.05) but not in response to RA or D alone. Although all diets contained equal amounts of PK, the kidney MK-4 concentration was higher in the D group (P < 0.05) and lower in the RA group (P < 0.05) compared with the RA+D or control groups. Renal PK concentrations were lower in the RA and RA+D groups than in the control and D groups (P < 0.05). These data suggest that 9-cis RA mitigated 1,25(OH)(2)D3-induced renal calcification by modifying the 1,25(OH)(2)D3-induced increase in ucMGP. The mechanisms by which 9-cis RA and 1,25(OH)(2)D3 alter vitamin K concentrations warrant further investigation.