Vitamin K2 covalently binds to Bak and induces Bak-mediated apoptosis

Plakevulin A induces apoptosis and suppresses IL-6-induced STAT3 activation in HL60 cells

(+)-Plakevulin A (1), an oxylipin isolated from an Okinawan sponge Plakortis sp. inhibits enzymatic inhibition of DNA polymerases (pols) α and δ and exhibits cytotoxicity against murine leukemia (L1210) and human cervix carcinoma (KB) cell lines. However, the half-maximal inhibitory concentration (IC50) value for cytotoxicity significantly differed from those observed for the enzymatic inhibition of pols α and β, indicating the presence of target protein(s) other than pols. This study demonstrated cytotoxicity against human promyelocytic leukemia (HL60), human cervix epithelioid carcinoma (HeLa), mouse calvaria-derived pre-osteoblast (MC3T3-E1), and human normal lung fibroblast (MRC-5) cell lines. This compound had selectivity to cancer cells over normal ones. Among these cell lines, HL60 exhibited the highest sensitivity to (+)-plakevulin A. (+)-Plakevulin A induced DNA fragmentation and caspase-3 activation in HL60 cells, indicating its role in apoptosis induction. Additionally, hydroxysteroid 17-β dehydrogenase 4 (HSD17B4) was isolated from the HL60 lysate as one of its binding proteins through pull-down experiments using its biotinylated derivative and neutravidin-coated beads. Moreover, (+)-plakevulin A suppressed the activation of interleukin 6 (IL-6)-induced signal transducer and activator of transcription 3 (STAT3). Because the knockdown or inhibition of STAT3 induces apoptosis and HSD17B4 regulates STAT3 activation, (+)-plakevulin A may induce apoptosis in HL60 cell lines by suppressing STAT3 activation, potentially by binding to HSD17B4. The present findings provide valuable information for the mechanism of its action.

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.

Beyond the Coagulation Cascade: Vitamin K and Its Multifaceted Impact on Human and Domesticated Animal Health

Vitamin K (VK) is an essential micronutrient impacting many systems in the body. This lipid-soluble vitamin is found in various plant and animal products and is absorbed via the lymphatic system. This biomolecule's importance to human health includes but is not limited to its promotion of brain, cardiovascular, bone, and immune functions. These biological properties are also necessary for maintaining domesticated animal health. The synergistic impact of both VK and vitamin D (VD) maximizes these health benefits, specifically for the circulatory and skeletal systems. This manuscript reviews VK's properties, molecular structures, nutrikinetics, mechanisms of action, daily requirements, safety in supplemental form, biomarkers used for its detection, and impacts on various organs. The purpose of synthesizing this information is to evaluate the potential uses of VK for the treatment or prevention of diseases.

Vitamin K2 in Health and Disease: A Clinical Perspective

Vitamins are essential organic compounds that vary widely in chemical structure and are vital in small quantities for numerous biochemical and biological functions. They are critical for metabolism, growth, development and maintaining overall health. Vitamins are categorised into two groups: hydrophilic and lipophilic. Vitamin K (VK), a lipophilic vitamin, occurs naturally in two primary forms: phylloquinone (VK1), found in green leafy vegetables and algae, and Menaquinones (VK2), present in certain fermented and animal foods and widely formulated in VK supplements. This review explores the possible factors contributing to VK deficiency, including dietary influences, and discusses the pharmacological and therapeutic potential of supplementary VK2, examining recent global clinical studies on its role in treating diseases such as osteoporosis, osteoarthritis, rheumatoid arthritis, cardiovascular disease, chronic kidney disease, diabetes, neurodegenerative disorders and cancers. The analysis includes a review of published articles from multiple databases, including Scopus, PubMed, Google Scholar, ISI Web of Science and CNKI, focusing on human studies. The findings indicate that VK2 is a versatile vitamin essential for human health and that a broadly positive correlation exists between VK2 supplementation and improved health outcomes. However, clinical data are somewhat inconsistent, highlighting the need for further detailed research into VK2's metabolic processes, biomarker validation, dose-response relationships, bioavailability and safety. Establishing a Recommended Daily Intake for VK2 could significantly enhance global health.

Pregnane X Receptor Signaling Pathway and Vitamin K: Molecular Mechanisms and Clinical Relevance in Human Health

This review explores the likely clinical impact of Pregnane X Receptor (PXR) activation by vitamin K on human health. PXR, initially recognized as a master regulator of xenobiotic metabolism in liver, emerges as a key regulator influencing intestinal homeostasis, inflammation, oxidative stress, and autophagy. The activation of PXR by vitamin K highlights its role as a potent endogenous and local agonist with diverse clinical implications. Recent research suggests that the vitamin K-mediated activation of PXR highlights this vitamin's potential in addressing pathophysiological conditions by promoting hepatic detoxification, fortifying gut barrier integrity, and controlling pro-inflammatory and apoptotic pathways. PXR activation by vitamin K provides an intricate association with cancer cell survival, particularly in colorectal and liver cancers, to provide new insights into potential novel therapeutic strategies. Understanding the clinical implications of PXR activation by vitamin K bridges molecular mechanisms with health outcomes, further offering personalized therapeutic approaches for complex diseases.

Vitamin K: New insights related to senescence and cancer metastasis

Several clinical trials and experimental studies have recently shown that vitamin K (VK) supplementation benefits the human body. Specifically, VK participates in coagulation and is associated with cellular senescence and cancer. VK has a potential anticancer effect in various cancers, such as pancreatic and prostate cancers. Through anti-inflammatory and antioxidant effects, VK can prevent senescence and inhibit cancer metastasis. Therefore, cancer prognosis can be improved by preventing cellular senescence. In addition, VK can inhibit the proliferation, growth, and differentiation of cancer cells through various mechanisms, including induction of c-myc and c-fos genes, regulation of B-cell lymphoma-2 (Bcl-2) and p21 genes, and angiogenesis inhibition. This review aims to discuss the relationship among VK, cellular senescence, and cancer metastasis and thus may improve comprehension of the specific functions of VK in human health. The potential application of VK as an adjuvant therapy for cancer (or in combination with traditional chemotherapy drugs or other vitamins) has also been highlighted.

Vitamin K Contribution to DNA Damage—Advantage or Disadvantage? A Human Health Response

Vitamin K is the common name for a group of compounds recognized as essential for blood clotting. The group comprises phylloquinone (K1)—a 2-methyl-3-phytyl-1,4-naphthoquinone; menaquinone (K2, MK)—a group of compounds with an unsaturated side chain in position 3 of a different number of isoprene units and a 1,4-naphthoquinone group and menadione (K3, MD)—a group of synthetic, water-soluble compounds 2-methyl-1,4-naphthoquinone. However, recent epidemiological studies suggest that vitamin K has various benefits that go beyond blood coagulation processes. A dietary intake of K1 is inversely associated with the risk of pancreatic cancer, K2 has the potential to induce a differentiation in leukemia cells or apoptosis of various types of cancer cells, and K3 has a documented anti-cancer effect. A healthy diet rich in fruit and vegetables ensures an optimal supply of K1 and K2, though consumers often prefer supplements. Interestingly, the synthetic form of vitamin K—menadione—appears in the cell during the metabolism of phylloquinone and is a precursor of MK-4, a form of vitamin K2 inaccessible in food. With this in mind, the purpose of this review is to emphasize the importance of vitamin K as a micronutrient, which not only has a beneficial effect on blood clotting and the skeleton, but also reduces the risk of cancer and other pro-inflammatory diseases. A proper diet should be a basic and common preventive procedure, resulting in a healthier society and reduced burden on healthcare systems.

New insights into vitamin K biology with relevance to cancer

Phylloquinone (vitamin K1) and menaquinones (vitamin K2 family) are essential for post-translational γ-carboxylation of a small number of proteins, including clotting factors. These modified proteins have now been implicated in diverse physiological and pathological processes including cancer. Vitamin K intake has been inversely associated with cancer incidence and mortality in observational studies. Newly discovered functions of vitamin K in cancer cells include activation of the steroid and xenobiotic receptor (SXR) and regulation of oxidative stress, apoptosis, and autophagy. We provide an update of vitamin K biology, non-canonical mechanisms of vitamin K actions, the potential functions of vitamin K-dependent proteins in cancer, and observational trials on vitamin K intake and cancer.

Role of Vitamin K in Selected Malignant Neoplasms in Women

The main function of vitamin K in the human organism is its activity in the blood clotting cascade. Epidemiological studies suggest that reduced intake of vitamin K may contribute to an increased risk of geriatric diseases such as atherosclerosis, dementia, osteoporosis, and osteoarthritis. A growing number of studies also indicate that vitamin K may be involved not only in preventing the development of certain cancers but it may also support classical cancer chemotherapy. This review article summarizes the results of studies on the anticancer effects of vitamin K on selected female malignancies, i.e., breast, cervical, and ovarian cancer, published over the past 20 years. The promising effects of vitamin K on cancer cells observed so far indicate its great potential, but also the need for expansion of our knowledge in this area by conducting extensive research, including clinical trials.

Association of Vitamin K Insufficiency With Cognitive Dysfunction in Community-Dwelling Older Adults

Vitamin K is a fat-soluble vitamin shown to be associated with several age-related diseases. Although a small number of epidemiological studies described the relationship between vitamin K status and cognitive impairment, vitamin K status was estimated by relatively special methods in previous reports. Here, we demonstrated the association of the concentration of undercarboxylated osteocalcin (ucOC) in serum, which is a biomarker for vitamin K insufficiency, with cognitive function in a cross-sectional study. A total of 800 community-dwelling older adults (mean age = 75.9) were invited to geriatric health examination, including a Mini-Mental State Examination (MMSE) and a blood test. By using binary logistic regression analysis, the risk of cognitive impairment equivalent or below the mild cognitive impairment level for each tertile of ucOC was examined, with the lowest tertile as the reference. We found a significant association of impaired cognitive function and concentration of ucOC in the highest tertile of ucOC, with the odds ratio of 1.65 (95% CI, 1.06 to 2.59, P = 0.028). When the analysis was repeated with each domain of MMSE, the highest tertile of ucOC was associated with impaired orientation, calculation, and language. As far as we know, this is the first report on the significant association of single ucOC measurement and cognitive impairment. Our analysis also suggests that vitamin K insufficiency could be associated with selected categories of cognitive function. Since the single measurement of ucOC in serum is a simple and widely available method for vitamin K evaluation, it could be useful as a biomarker of neurodegenerative diseases affecting the cognitive functions.

Correlation Between Serum Concentrations of Menaquinone-4 and Developmental Quotients in Children With Autism Spectrum Disorder

Objective: The vitamin K family has a wide range of effects in the body, including the central nervous system. Menaquinone-4 (MK-4), a form of vitamin K2, is converted from phylloquinone (PK), which is the main source of dietary vitamin K and is the main form of vitamin K in the brain. We conducted this study to investigate the serum concentration of MK-4 and the correlations between MK-4 and developmental quotients in children with autism spectrum disorder (ASD). Methods: We selected 731 children with ASD who were diagnosed for the first time. During the same period, 332 neurotypical children who underwent regular physical examinations in our outpatient department were selected as the TD group. We investigated the general situation of children, including gender and age. Children in ASD group were assessed for autistic symptoms and development quotients, including Autism Behavior Checklist (ABC), Childhood Autism Rating Scale (CARS), ADOS-2, and Griffiths Development Scales-Chinese Language Edition (GDS-C). Both groups of children were tested for serum menaquinone-4. We compared serum menaquinone-4 levels of ASD group and TD group. We then conducted a correlation analysis between the level of menaquinone-4 and the developmental quotient of children with ASD. Results: The results of this study indicate that the serum concentration of MK-4 in children with ASD is lower than that in children with typical development (t = -2.702, P = 0.007). The serum concentration of MK-4 is related to the developmental quotients of several subscales in ASD children, and this correlation is more obvious in males. Conclusion: we conclude that MK-4 is present in lower concentrations in children with ASD, which may affect cognition and developmental quotients. The role of MK-4 in ASD needs to be further explored.

PPM-18, an Analog of Vitamin K, Induces Autophagy and Apoptosis in Bladder Cancer Cells Through ROS and AMPK Signaling Pathways

PPM-18, identified as a novel analog of vitamin K, has been reported to play a critical role in the suppression of seizures. However, the concerns that whether PPM-18, like vitamin K, exerts anticancer activity remain to be further investigated. Here, we found that PPM-18 remarkably suppressed the proliferation and induced apoptosis in bladder cancer cells. Furthermore, a significant autophagic effect of PPM-18 on bladder cancer cells was also demonstrated, which profoundly promoted apoptotic cell death. Mechanistically, PPM-18 activated AMP-activated protein kinase (AMPK), whereas it repressed PI3K/AKT and mTORC1 pathways in bladder cancer cells. Inhibition of AMPK markedly relieved PPM-18–induced autophagy and apoptosis, indicating that PPM-18 is able to induce autophagy and apoptosis in bladder cancer cells via AMPK activation. Moreover, reactive oxygen species (ROS) were notably accumulated in PPM-18–treated bladder cancer cells, and treatment with ROS scavengers not only eliminated ROS production but also abrogated AMPK activation, which eventually rescued bladder cancer cells from PPM-18–triggered autophagy and apoptotic cell death. In bladder cancer xenografts, the anticancer activities of PPM-18, including suppressing the growth of tumors and inducing autophagy and apoptosis in tumor cells, were also established. Collectively, this study was the first to demonstrate the anticancer effect of PPM-18 on bladder cancer cells in vitro and in vivo through eliciting autophagy and apoptosis via ROS and AMPK pathways, which might provide new insights into the potential utilization of PPM-18 for future bladder cancer treatment.

Growth Inhibitory Effects of Ester Derivatives of Menahydroquinone-4, the Reduced Form of Vitamin K2(20), on All-Trans Retinoic Acid-Resistant HL60 Cell Line

The first-choice drug for acute promyelocytic leukemia (APL), all-trans retinoic acid (ATRA), frequently causes drug-resistance and some adverse effects. Thus, an effective and safe agent for ATRA-resistant APL is needed. Menaquinone-4 (MK-4, vitamin K₂₍₂₀₎), used for osteoporosis treatment, does not have serious adverse effects. It has been reported that MK-4 has growth-inhibitory effects on HL60 cells by inducing apoptosis via the activation of Bcl-2 antagonist killer 1 (BAK). However, the effect of MK-4 on ATRA-resistant APL has not been reported. Here, we show that ester derivatives of menahydroquinone-4 (MKH; a reduced form of MK-4), MKH 1,4-bis-N,N-dimethylglycinate (MKH-DMG) and MKH 1,4-bis-hemi-succinate (MKH-SUC), exerted strong growth-inhibitory effects even on ATRA-resistant HL60 (HL-60R) cells compared with ATRA and MK-4. MKH delivery after MKH-SUC treatment was higher than that after MK-4 treatment, and the results indicated apoptosis induced by BAK activation. In contrast, for MKH-DMG, reconversion to MKH was slow and apoptosis was not observed. We suggest that the ester forms, including monoesters of MKH-DMG, exhibit another mechanism independent of apoptosis. In conclusion, the MKH derivatives (MKH-SUC and MKH-DMG) inhibited not only HL60 cells but also HL-60R cells, indicating a potential to overcome ATRA resistance.

Regulatory Nucleotide Sequence Signals for Expression of the Genes Encoding Ribosomal Proteins

Ribosomal proteins (RPs) are essential components that translate genetic information from mRNA templates into proteins. Their expressional dysregulation adversely affects the survival and growth of human cells. Nevertheless, little is known about the nucleotide sequences regulating the expression of RPs. Genome-wide associations for expression level of 70 RP genes were conducted across expression stages. Eighteen expression regulatory quantitative trait loci (erQTLs) were identified for protein abundances of 21 RPs (P < 1 × 10^-5), but not for their mRNA expression and ribosome occupancy (P > 1 × 10^-5). These erQTLs for protein abundance (pQTLs) were all trans-acting. Three of the pQTLs were associated with the expression of long noncoding RNAs (lncRNAs). Target genes of these lncRNAs may produce ribosomal components or may control the metabolic cues for ribosome synthesis. mRNAs of the RP genes extensively interact with miRNAs. The protein-specific erQTLs may become engendered by intensive miRNA controls at the translational stage, which in turn can produce RPs efficient in handling instantaneous cell requirements. This study suggests that the expression levels of RPs may be greatly influenced by trans-acting regulation, presumably via interference of miRNAs and target genes of lncRNAs. Further studies are warranted to examine the molecular functions of pQTLs presented in this study and to understand the underlying regulatory mechanisms of gene expression of RPs.

Vitamin K2 promotes PI3K/AKT/HIF-1α-mediated glycolysis that leads to AMPK-dependent autophagic cell death in bladder cancer cells

Vitamin K2 has been shown to exert remarkable anticancer activity. However, the detailed mechanism remains unclear. Here, our study was the first to show that Vitamin K2 significantly promoted the glycolysis in bladder cancer cells by upregulating glucose consumption and lactate production, whereas inhibited TCA cycle by reducing the amounts of Acetyl-CoA. Moreover, suppression of PI3K/AKT and HIF-1α attenuated Vitamin K2-increased glucose consumption and lactate generation, indicating that Vitamin K2 promotes PI3K/AKT and HIF-1α-mediated glycolysis in bladder cancer cells. Importantly, upon glucose limitation, Vitamin K2-upregulated glycolysis markedly induced metabolic stress, along with AMPK activation and mTORC1 pathway suppression, which subsequently triggered AMPK-dependent autophagic cell death. Intriguingly, glucose supplementation profoundly abrogated AMPK activation and rescued bladder cancer cells from Vitamin K2-triggered autophagic cell death. Furthermore, both inhibition of PI3K/AKT/HIF-1α and attenuation of glycolysis significantly blocked Vitamin K2-induced AMPK activation and subsequently prevented autophagic cell death. Collectively, these findings reveal that Vitamin K2 could induce metabolic stress and trigger AMPK-dependent autophagic cell death in bladder cancer cells by PI3K/AKT/HIF-1α-mediated glycolysis promotion.

Molecular mechanisms of thalidomide and its derivatives

Thalidomide, originally developed as a sedative drug, causes multiple defects due to severe teratogenicity, but it has been re-purposed for treating multiple myeloma, and derivatives such as lenalidomide and pomalidomide have been developed for treating blood cancers. Although the molecular mechanisms of thalidomide and its derivatives remained poorly understood until recently, we identified cereblon (CRBN), a primary direct target of thalidomide, using ferrite glycidyl methacrylate (FG) beads. CRBN is a ligand-dependent substrate receptor of the E3 ubiquitin ligase complex cullin-RING ligase 4 (CRL4^CRBN). When a ligand such as thalidomide binds to CRBN, it recognizes various 'neosubstrates' depending on the shape of the ligand. CRL4^CRBN binds many neosubstrates in the presence of various ligands. CRBN has been utilized in a novel protein knockdown technology named proteolysis targeting chimeras (PROTACs). Heterobifunctional molecules such as dBET1 are being developed to specifically degrade proteins of interest. Herein, we review recent advances in CRBN research.

Vitamin K2 induces non-apoptotic cell death along with autophagosome formation in breast cancer cell lines

BACKGROUND

Vitamin K₂ (VK2) has been reported to induce apoptosis in many types of cancer cells including leukemia. However, there are no precise reports regarding the breast cancer cells. From the stand point of clinical implications of VK2 including chemoprevention, we investigated the effects of VK2 on breast cancer cell lines.

METHODS

Breast cancer cell lines were cultured with VK2, and the cytotoxicity and cell death phenotype were examined. The HL-60 leukemia cells were used as a control for VK2-induced apoptosis.

RESULTS

VK2 exhibited the cytotoxic effect, especially in triple negative breast cancer cell lines, namely, MDA-MB-231 and MDA-MB-468. However, in contrast to HL-60 cells, typical features of the cells undergoing apoptosis, such as chromatin condensation, nuclear fragments, and cleavage of caspase-3 were not detected. Transmission electron microscopy exhibited an increased number of autophagosomes/autolysosomes with plasma membrane integrity. An autophagy inhibitor, 3-methyladenine, apparently attenuated VK2-induced cytotoxicity, which indicated the involvement of autophagy-dependent cell death. Interestingly, both VK2-induced non-apoptotic cell death in MDA-MB-231 cells and VK2-induced apoptosis in HL-60 cells were suppressed in the presence of reactive oxygen species (ROS) scavengers. Therefore, ROS production by VK2 seems to be located up-stream in the molecular machinery for both the types of cell death execution.

CONCLUSION

The VK2 induced non-apoptotic cell death along with autophagy, in triple negative breast cancer cell lines. Cell death phenotype induced by VK2 appears to differ among the type of cancers. This suggests the possibility of using VK2 for the breast cancer therapy.

Multiple Modes of Vitamin K Actions in Aging-Related Musculoskeletal Disorders

Vitamin K is a fat-soluble vitamin that was originally found as an essential factor for blood coagulation. With the discovery of its role as a co-factor for γ-glutamyl carboxylase (GGCX), its function for blood coagulation was understood as the activation of several blood coagulation factors by their γ-carboxylation. Over the last two decades, other modes of vitamin K actions have been discovered, such as the regulation of transcription by activating the steroid and xenobiotic receptor (SXR), physical association to 17β-Hydroxysteroid dehydrogenase type 4 (17β-HSD4), covalent modification of Bcl-2 antagonist killer 1 (Bak), and the modulation of protein kinase A (PKA) activity. In addition, several epidemiological studies have revealed that vitamin K status is associated with some aging-related diseases including osteoporosis, osteoarthritis, and sarcopenia. Clinical studies on single nucleotide polymorphisms of GGCX suggested an association between higher GGCX activity and bone protective effect, while recent findings using conditional knockout mice implied that a contribution in protective effect for bone loss by GGCX in osteoblastic lineage was unclear. GGCX in other cell lineages or in other tissues might play a protective role for osteoporosis. Meanwhile, animal experiments by our groups among others revealed that SXR, a putative receptor for vitamin K, could be important in the bone metabolism. In terms of the cartilage protective effect of vitamin K, both GGCX- and SXR-dependent mechanisms have been suggested. In clinical studies on osteoarthritis, the γ-carboxylation of matrix Gla protein (MGP) and gla-rich protein (GRP) may have a protective role for the disease. It is also suggested that SXR signaling has protective role for cartilage by inducing family with sequence similarity 20a (Fam20a) expression in chondrocytes. In the case of sarcopenia, a high vitamin K status in plasma was associated with muscle strength, large muscle mass, and high physical performance in some observational studies. However, the basic studies explaining the effects of vitamin K on muscular tissue are limited. Further research on vitamin K will clarify new biological mechanisms which contribute to human longevity and health through the prevention and treatment of aging-related musculoskeletal disorders.

Research progress on the anticancer effects of vitamin K2

Despite the availability of multiple therapeutic methods for patients with cancer, the long-term prognosis is not satisfactory in a number of different cancer types. Vitamin K2 (VK2), which exerts anticancer effects on a number of cancer cell lines, is considered to be a prospective novel agent for the treatment of cancer. The present review aims to summarize the results of studies in which VK2 was administered either to patients with cancer or animals inoculated with cancerous cells, particularly investigating the inhibitory effects of VK2 on cancerous cells, primarily involving cell-cycle arrest, cell differentiation, apoptosis, autophagy and invasion. The present review summarizes evidence stating that treatment with VK2 could positively inhibit the growth of cancer cells, making it a potentially useful approach for the prevention and clinical treatment of cancer. Additionally, the combination treatment of VK2 and established chemotherapeutics may achieve better results, with fewer side effects. Therefore, more attention should be paid to the effects of micronutrients on tumors.

Vitamin K2, a menaquinone present in dairy products targets castration-resistant prostate cancer cell-line by activating apoptosis signaling

The aim of this study was to evaluate the therapeutic effects of vitamin K2 (VK2) on castration-resistant prostate cancer (CRPC) and its anti-cancer mechanisms in a pre-clinical study using a VCaP cell line (ATCC^® CRL-2876™) which was established from a vertebral bone metastasis from a patient with hormone refractory prostate cancer. Our data showed that VK2 significantly inhibited CRPC VCaP cell proliferation in a dose-dependent manner at 48 h treatment in vitro. In addition, VK2 reduced the migration potential of VCaP cells and inhibited anchorage-independent growth of these cells. Our results also showed that VK2 induces apoptosis in VCaP cells. Furthermore, VK2 enforced growth arrest in VCaP cells by activating cellular senescence. Notably, VK2 treatment elevated the levels of reactive oxygen species in VCaP cells. Western blot analysis revealed that VK2 downregulated the expression of androgen receptor, BiP, survivin, while activating caspase-3 and -7, PARP-1 cleavage, p21 and DNA damage response marker, phospho-H2AX in VCaP cells. In conclusion, our study suggests that VK2 might be a potential anti-cancer agent for CRPC by specifically targeting key anti-apoptotic, cell cycle progression and metastasis-promoting signaling molecules.

Vitamin K and its analogs: Potential avenues for prostate cancer management

Epidemiological studies have demonstrated a relationship between cancer incidence and dietary habits. Especially intake of certain essential nutrients like vitamins has been shown to be beneficial in experimental studies and some clinical trials. Vitamin K (VK) is an essential nutrient involved in the blood clotting cascade, and there are considerable experimental data demonstrating its potential anticancer activity in several cancer types including prostate cancer. Previous in vitro and in vivo studies have focused mainly on anti-oxidative effects as the underlying anticancer mechanism of VK. However, recent studies reveal that VK inhibits the growth of cancer cells through other mechanisms, including apoptosis, cell cycle arrest, autophagy, and modulation of various transcription factors such as Myc and Fos. In the present review, we focus on the anticancer effect of dietary VK and its analogs on prostate cancer, with an emphasis on the signaling pathways that are activated following exposure to these compounds. This review also highlights the potential of VK and its derivatives as an adjuvant treatment in combination with other vitamins or with chemotherapeutic drugs. Based on our recent results and a review of the existing literature, we present evidence that VK and its derivatives can potentially be explored as cancer therapy, especially for prostate cancer.

Vitamin K2 Induces Mitochondria-Related Apoptosis in Human Bladder Cancer Cells via ROS and JNK/p38 MAPK Signal Pathways

The effects of vitamin K2 on apoptosis in a variety of cancer cells have been well established in previous studies. However, the apoptotic effect of vitamin K2 on bladder cancer cells has not been evaluated. The aim of this study is to examine the apoptotic activity of Vitamin K2 in bladder cancer cells and investigate the underlying mechanism. In this study, Vitamin K2 induced apoptosis in bladder cancer cells through mitochondria pathway including loss of mitochondria membrane potential, cytochrome C release and caspase-3 cascade. Furthermore, the phosphorylation of c-Jun N-terminal kinase (JNK) and p38 MAPK was detected in Vitamin K2-treated cells and both SP600125 (an inhibitor of JNK) and SB203580 (an inhibitor of p38 MAPK) completely abolished the Vitamin K2-induced apoptosis and loss of mitochondria membrane potential. Moreover, the generation of reactive oxygen species (ROS) was detected in bladder cancer cells, upon treatment of vitamin K2 and the anti-oxidant N-acetyl cysteine (NAC) almost blocked the Vitamin K2-triggered apoptosis, loss of mitochondria membrane potential and activation of JNK and p38 MAPK. Taken together, these findings revealed that Vitamin K2 induces apoptosis in bladder cancer cells via ROS-mediated JNK/p38 MAPK and Mitochondrial pathways.

Expression levels of the BAK1 and BCL2 genes highlight the role of apoptosis in age-related hearing impairment

Age-related hearing impairment (ARHI) is a progressive and a common sensory disorder in the elderly and will become an increasingly important clinical problem given the growing elderly population. Apoptosis of cochlear cells is an important factor in animal models of ARHI. As these cells cannot regenerate, their loss leads to irreversible hearing impairment. Identification of molecular mechanisms can facilitate disease prevention and effective treatment. In this study, we compared the expression of the genes BAK1 and BCL2 as two arms of the intrinsic apoptosis pathway between patients with ARHI and healthy subjects. ARHI and healthy subjects were selected after an ear nose throat examination, otoscopic investigation, and pure tone audiometry. RNA was extracted from peripheral blood samples, and relative gene expression levels were measured using quantitative real-time polymerase chain reaction. BAK1 and the BAK1/BCL2 ratio were statistically significantly upregulated in the ARHI subjects. The BAK1/BCL2 ratio was positively correlated with the results of the audiometric tests. Our results indicate that BAK-mediated apoptosis may be a core mechanism in the progression of ARHI in humans, similar to finding in animal models. Moreover, the gene expression changes in peripheral blood samples could be used as a rapid and simple biomarker for early detection of ARHI.

Carboxylic Derivatives of Vitamin K2 Inhibit Hepatocellular Carcinoma Cell Growth through Caspase/Transglutaminase-Related Signaling Pathways

Chemoprevention of hepatocellular carcinoma (HCC) is one of the most challenging aspects of medical research. Vitamin K2 (VK2) has been suggested for its chemopreventive role in treatment of HCC, while inconsistent results in clinical trials have been reported. The present study was initiated to add to our insight into the anti-HCC cell proliferative effect of VK2 and its derivatives from a viewpoint of chemical structure. No significant effect was observed with original VK2, while VK2 derivatives bearing both isoprene units and a carboxyl-terminated side chain dose-dependently inhibited the growth of HCC cells without affecting normal liver cells. Loss-of-function analyses revealed that the anti-HCC cell activity by the VK2 derivatives was not mediated by a VK2 binding protein Bcl-2 homologous antagonist/killer (Bak) but rather associated with caspase/transglutaminase-related signaling pathways. Further studies on the carboxylic derivatives of VK2 bearing isoprene structural units introduced in this study might shed new light on the systemic treatment and prevention of HCC.

Metabolomics identifies the intersection of phosphoethanolamine with menaquinone-triggered apoptosis in an in vitro model of leukemia

Altered metabolism is increasingly acknowledged as an important aspect of cancer, and thus serves as a potentially fertile area for the identification of therapeutic targets or leads. Our recent work using transcriptional data to predict metabolite levels in cancer cells led to preliminary evidence of the antiproliferative role of menaquinone (vitamin K2) in the Jurkat cell line model of acute lymphoblastic leukemia. However, nothing is known about the direct metabolic impacts of menaquinone in cancer, which could provide insights into its mechanism of action. Here, we used metabolomics to investigate the process by which menaquinone exerts antiproliferative activity on Jurkat cells. We first validated the dose-dependent, semi-selective, pro-apoptotic activity of menaquinone treatment on Jurkat cells relative to non-cancerous lymphoblasts. We then used mass spectrometry-based metabolomics to identify systems-scale changes in metabolic dynamics that are distinct from changes induced in non-cancerous cells or by other chemotherapeutics. One of the most significantly affected metabolites was phosphoethanolamine, which exhibited a two-fold increase in menaquinone-treated Jurkat cells compared to vehicle-treated cells at 24 h, growing to a five-fold increase at 72 h. Phosphoethanolamine elevation was observed prior to the induction of apoptosis, and was not observed in menaquinone-treated lymphoblasts or chemotherapeutic-treated Jurkat cells. We also validated the link between menaquinone and phosphoethanolamine in an ovarian cancer cell line, suggesting potentially broad applicability of their relationship. This metabolomics-based work is the first detailed characterization of the metabolic impacts of menaquinone treatment and the first identified link between phosphoethanolamine and menaquinone-induced apoptosis.

Vitamin K deficiency leads to exacerbation of murine dextran sulfate sodium-induced colitis

BACKGROUND

Patients with inflammatory bowel disease (IBD) often exhibit vitamin K deficiency. Vitamin K has been shown to inhibit inflammation via interleukin (IL)-6 suppression. This study aimed to evaluate the effect of vitamin K in a murine model of colitis.

METHODS

Colitis was induced using dextran sulfate sodium (DSS) in mice fed either a vitamin K-deficient (K-def) or a vitamin K-supplemented (K-sup) diet. The clinical and histological severity of colitis was assessed, and levels of cytokine production from the spleen and colonic lamina propria were measured by enzyme-linked immunosorbent assay and quantitative real-time reverse transcription polymerase chain reaction. Cytokine expression levels in CD4(+), CD11b(+), and CD19(+) cells in the presence and absence of vitamin K [menatetrenone (MK-4)] were measured in vitro and apoptosis was determined by caspase 3/7 activity and Annexin V staining.

RESULTS

DSS administration resulted in significantly more severe body weight loss, shorter colon length, and higher histological scores in mice fed a K-def diet than those fed a K-sup diet. IL-6 expression in lamina propria mononuclear cells was significantly higher in the K-def group than in the K-sup group. IL-6 expression was significantly decreased in the presence of MK-4 in CD19(+) cells, but not in the CD4(+) and CD11b(+) subpopulations. Apoptotic cell population in CD19(+) cells was increased in the presence of MK-4 in vitro and in vivo.

CONCLUSIONS

Vitamin K exerts a protective effect against DSS colitis; this effect is associated with IL-6 downregulation. Vitamin K could be a potential treatment target for IBD.

Vitamin K and hepatocellular carcinoma: The basic and clinic

Vitamin K (VK), which was originally identified as a cofactor involved in the production of functional coagulation factors in the liver, has been shown to be involved in various aspects of physiological and pathological events, including bone metabolism, cardiovascular diseases and tumor biology. The mechanisms and roles of VK are gradually becoming clear. Several novel enzymes involved in the VK cycle were identified and have been shown to be linked to tumorigenesis. The VKs have been shown to suppress liver cancer cell growth through multiple signaling pathways via the transcription factors and protein kinases. A VK2 analog was applied to the chemoprevention of hepatocellular carcinoma (HCC) recurrence after curative therapy and was shown to have beneficial effects, both in the suppression of HCC recurrence and in patient survival. Although a large scale randomized control study failed to demonstrate the suppression of HCC recurrence, a meta-analysis suggested a beneficial effect on the long-term survival of HCC patients. However, the beneficial effects of VK administration alone were not sufficient to prevent or treat HCC in clinical settings. Thus its combination with other anti-cancer reagents and the development of more potent novel VK derivatives are the focus of ongoing research which seeks to achieve satisfactory therapeutic effects against HCC.

Real-time cell analysis of the inhibitory effect of vitamin K2 on adhesion and proliferation of breast cancer cells

Breast cancer is the most prevalent cancer type worldwide. Continued efforts to improve treatment strategies for patients with breast cancer will be instrumental in reducing the death rates associated with this disease. In particular, the triple-negative breast cancer subtype of breast cancer has no targeted therapy available so it is essential to continue to work on any potential therapies. Vitamin K (VK) is known for its essential role in the clotting cascade. The antitumor properties of VK derivatives have been reported in both hepatocellular carcinoma and glioblastoma. Our hypothesis was that menaquinone-4, the most common form of vitamin K2 (VK2), is an effective anticancer agent against breast cancer cell types. In this study, we used a novel impedance-based live cell monitoring platform (xCELLigence) to determine the effects of VK derivatives on the triple-negative breast cancer cell line, MDA-MB-231, and the HER2+ breast cancer cell line, MDA-MB-453. Cells were treated with varying concentrations of menaquinone-4 (VK2) previously reported to have an antiproliferative effect on human glioblastoma cells. After initial testing, these concentrations were adjusted to 100, 125, and 150 μmol/L. A significant dose-dependent, growth inhibitory effect was found when cells were treated at these concentrations. These effects were seen in both adhesion and proliferation phases and show a dramatic reduction in cell growth. Additional analysis of MDA-MB-231 cells treated with VK2 (100 μmol/L) in combination with a low-glucose nutrient media showed a further decrease in adhesion and viability. This is the first study of its kind showing the real-time effects of VK derivatives on breast cancer cells and suggests that dietary factors may be an important consideration for patients.

Expression profiling reveals genes involved in the regulation of wool follicle bulb regression and regeneration in sheep

Wool is an important material in textile manufacturing. In order to investigate the intrinsic factors that regulate wool follicle cycling and wool fiber properties, Illumina sequencing was performed on wool follicle bulb samples from the middle anagen, catagen and late telogen/early anagen phases. In total, 13,898 genes were identified. KRTs and KRTAPs are the most highly expressed gene families in wool follicle bulb. In addition, 438 and 203 genes were identified to be differentially expressed in wool follicle bulb samples from the middle anagen phase compared to the catagen phase and the samples from the catagen phase compared to the late telogen/early anagen phase, respectively. Finally, our data revealed that two groups of genes presenting distinct expression patterns during the phase transformation may have important roles for wool follicle bulb regression and regeneration. In conclusion, our results demonstrated the gene expression patterns in the wool follicle bulb and add new data towards an understanding of the mechanisms involved in wool fiber growth in sheep.

Recent trends in the metabolism and cell biology of vitamin K with special reference to vitamin K cycling and MK-4 biosynthesis

In contrast to other fat-soluble vitamins, dietary vitamin K is rapidly lost to the body resulting in comparatively low tissue stores. Deficiency is kept at bay by the ubiquity of vitamin K in the diet, synthesis by gut microflora in some species, and relatively low vitamin K cofactor requirements for γ-glutamyl carboxylation. However, as shown by fatal neonatal bleeding in mice that lack vitamin K epoxide reductase (VKOR), the low requirements are dependent on the ability of animals to regenerate vitamin K from its epoxide metabolite via the vitamin K cycle. The identification of the genes encoding VKOR and its paralog VKOR-like 1 (VKORL1) has accelerated understanding of the enzymology of this salvage pathway. In parallel, a novel human enzyme that participates in the cellular conversion of phylloquinone to menaquinone (MK)-4 was identified as UbiA prenyltransferase-containing domain 1 (UBIAD1). Recent studies suggest that side-chain cleavage of oral phylloquinone occurs in the intestine, and that menadione is a circulating precursor of tissue MK-4. The mechanisms and functions of vitamin K recycling and MK-4 synthesis have dominated advances made in vitamin K biochemistry over the last five years and, after a brief overview of general metabolism, are the main focuses of this review.

Ectopic expression of the TERE1 (UBIAD1) protein inhibits growth of renal clear cell carcinoma cells: altered metabolic phenotype associated with reactive oxygen species, nitric oxide and SXR target genes involved in cholesterol and lipid metabolism

Current studies of the TERE1 (UBIAD1) protein emphasize its multifactorial influence on the cell, in part due to its broad sub-cellular distribution to mitochondria, endoplasmic reticulum and golgi. However, the profound effects of TERE1 relate to its prenyltransferase activity for synthesis of the bioactive quinones menaquinone and COQ10. Menaquinone (aka, vitamin K-2) serves multiple roles: as a carrier in mitochondrial electron transport, as a ligand for SXR nuclear hormone receptor activation, as a redox modulator, and as an alkylator of cellular targets. We initially described the TERE1 (UBIAD1) protein as a tumor suppressor based upon reduced expression in urological cancer specimens and the inhibition of growth of tumor cell lines/xenografts upon ectopic expression. To extend this potential tumor suppressor role for the TERE1 protein to renal cell carcinoma (RCC), we applied TERE1 immunohistochemistry to a TMA panel of 28 RCC lesions and determined that in 57% of RCC lesions, TERE1 expression was reduced (36%) or absent (21%). Ectopic TERE1 expression caused an 80% decrease in growth of Caki-1 and Caki-2 cell lines, a significantly decreased colony formation, and increased caspase 3/7 activity in a panel of RCC cell lines. Furthermore, TERE1 expression increased mitochondrial oxygen consumption and hydrogen production, oxidative stress and NO production. Based on the elevated cholesterol and altered metabolic phenotype of RCC, we also examined the effects of TERE1 and the interacting protein TBL2 on cellular cholesterol. Ectopic TERE1 or TBL2 expression in Caki-1, Caki-2 and HEK 293 cells reduced cholesterol by up to 40%. RT-PCR analysis determined that TERE1 activated several SXR targets known to regulate lipid metabolism, consistent with predictions based on its role in menaquinone synthesis. Loss of TERE1 may contribute to the altered lipid metabolic phenotype associated with progression in RCC via an uncoupling of ROS/RNS and SXR signaling from apoptosis by elevation of cholesterol.

Structural and functional insights into human vitamin K epoxide reductase and vitamin K epoxide reductase-like1

Human vitamin K epoxide reductase (hVKOR) is a small integral membrane protein involved in recycling vitamin K. hVKOR produces vitamin K hydroquinone, a crucial cofactor for γ-glutamyl carboxylation of vitamin K dependent proteins, which are necessary for blood coagulation. Because of this, hVKOR is the target of a common anticoagulant, warfarin. Spurred by the identification of the hVKOR gene less than a decade ago, there have been a number of new insights related to this protein. Nonetheless, there are a number of key issues that have not been resolved; such as where warfarin binds hVKOR, or if human VKOR shares the topology of the structurally characterized but distantly related prokaryotic VKOR. The pharmacogenetics and single nucleotide polymorphisms of hVKOR used in personalized medicine strategies for warfarin dosing should be carefully considered to inform the debate. The biochemical and cell biological evidence suggests that hVKOR has a distinct fold from its ancestral protein, though the controversy will likely remain until structural studies of hVKOR are accomplished. Resolving these issues should impact development of new anticoagulants. The paralogous human protein, VKOR-like1 (VKORL1) was recently shown to also participate in vitamin K recycling. VKORL1 was also recently characterized and assigned a functional role as a housekeeping protein involved in redox homeostasis and oxidative stress with a potential role in cancer regulation. As the physiological interplay between these two human paralogs emerge, the impacts could be significant in a number of diverse fields from coagulation to cancer.