Increased nuclear expression and transactivation of vitamin D receptor by the cardiotonic steroid bufalin in human myeloid leukemia cells

Modulation of the vitamin D receptor by traditional Chinese medicines and bioactive compounds: potential therapeutic applications in VDR-dependent diseases

The Vitamin D receptor (VDR) is a crucial nuclear receptor that plays a vital role in various physiological functions. To a larger extent, the genomic effects of VDR maintain general wellbeing, and its modulation holds implications for multiple diseases. Current evidence regarding using vitamin D or its synthetic analogs to treat non-communicable diseases is insufficient, though observational studies suggest potential benefits. Traditional Chinese medicines (TCMs) and bioactive compounds derived from natural sources have garnered increasing attention. Interestingly, TCM formulae and TCM-derived bioactive compounds have shown promise in modulating VDR activities. This review explores the intriguing potential of TCM and bioactive compounds in modulating VDR activity. We first emphasize the latest information on the genetic expression, function, and structure of VDR, providing a comprehensive understanding of this crucial receptor. Following this, we review several TCM formulae and herbs known to influence VDR alongside the mechanisms underpinning their action. Similarly, we also discuss TCM-based bioactive compounds that target VDR, offering insights into their roles and modes of action.

Bufalin for an innovative therapeutic approach against cancer

Bufalin is an endogenous cardiotonic steroid, first discovered in toad venom but also found in the plasma of healthy humans, with anti-tumour activities in different cancer types. The current review is focused on its mechanisms of action and highlights its very large spectrum of effects both in vitro and in vivo. All leads to the conclusion that bufalin mediates its effects by affecting all the hallmarks of cancer and seems restricted to cancer cells avoiding side effects. Bufalin decreases cancer cell proliferation by acting on the cell cycle and inducing different mechanisms of cell death including apoptosis, necroptosis, autophagy and senescence. Bufalin also moderates metastasis formation by blocking migration and invasion as well as angiogenesis and by inducing a phenotype switch towards differentiation and decreasing cancer cell stemness. Regarding its various mechanisms of action in cancer cells, bufalin blocks overactivated signalling pathways and modifies cell metabolism. Moreover, bufalin gained lately a huge interest in the field of drug resistance by both reversing various drug resistance mechanisms and affecting the immune microenvironment. Together, these data support bufalin as a quite promising new anti-cancer drug candidate.

Apoptotic Pathway as the Therapeutic Target for Anticancer Traditional Chinese Medicines

Cancer is a leading cause of morbidity and mortality worldwide. Apoptosis is a process of programmed cell death and it plays a vital role in human development and tissue homeostasis. Mounting evidence indicates that apoptosis is closely related to the survival of cancer and it has emerged as a key target for the discovery and development of novel anticancer drugs. Various studies indicate that targeting the apoptotic signaling pathway by anticancer drugs is an important mechanism in cancer therapy. Therefore, numerous novel anticancer agents have been discovered and developed from traditional Chinese medicines (TCMs) by targeting the cellular apoptotic pathway of cancer cells and shown clinically beneficial effects in cancer therapy. This review aims to provide a comprehensive discussion for the role, pharmacology, related biology, and possible mechanism(s) of a number of important anticancer TCMs and their derivatives mainly targeting the cellular apoptotic pathway. It may have important clinical implications in cancer therapy.

Human cytochrome P450 enzymes 5-51 as targets of drugs and natural and environmental compounds: mechanisms, induction, and inhibition - toxic effects and benefits

Cytochrome P450 (P450, CYP) enzymes have long been of interest due to their roles in the metabolism of drugs, pesticides, pro-carcinogens, and other xenobiotic chemicals. They have also been of interest due to their very critical roles in the biosynthesis and metabolism of steroids, vitamins, and certain eicosanoids. This review covers the 22 (of the total of 57) human P450s in Families 5-51 and their substrate selectivity. Furthermore, included is information and references regarding inducibility, inhibition, and (in some cases) stimulation by chemicals. We update and discuss important aspects of each of these 22 P450s and questions that remain open.

New therapeutic aspects of steroidal cardiac glycosides: the anticancer properties of Huachansu and its main active constituent Bufalin

Aim of the review

In the past decade, increasing research attention investigated the novel therapeutic potential of steroidal cardiac glycosides in cancer treatment. Huachansu and its main active constituent Bufalin have been studied in vitro, in vivo and clinical studies. This review aims to summarize the multi-target and multi-pathway pharmacological effects of Bufalin and Huachansu in the last decade, with the aim of providing a more comprehensive view and highlighting the recently discovered molecular mechanisms.

Results

Huachansu and its major derivative, Bufalin, had been found to possess anti-cancer effects in a variety of cancer cell lines both in vitro and in vivo. The underlying anti-cancer molecular mechanisms mainly involved anti-proliferation, apoptosis induction, anti-metastasis, anti-angiogenesis, epithelial-mesenchymal transition inhibition, anti-inflammation, Na⁺/K⁺-ATPase activity targeting, the steroid receptor coactivator family inhibitions, etc. Moreover, the potential side-effects and toxicities of the toad extract, Huachansu, and Bufalin, including hematological, gastrointestinal, mucocutaneous and cardiovascular adverse reactions, were reported in animal studies and clinic trails.

Conclusions

Further research is needed to elucidate the potential drug-drug interactions and multi-target interaction of Bufalin and Huachansu. Large-scale clinical trials are warranted to translate the knowledge of the anticancer actions of Bufalin and Huachansu into clinical applications as effective and safe treatment options for cancer patients in the future.

Transferrin and folic acid co-modified bufalin-loaded nanoliposomes: preparation, characterization, and application in anticancer activity

Aim

The aim of this study was to prepare transferrin (Tf) and folic acid (FA) co-modified bufalin (BF) liposomes for lung cancer treatment.

Method

In this study, (FA+Tf) BF-LPs were prepared using the high-pressure homogenization method.

Results

The EE% and DL% of prepared LPs were 82.3% and 10.7%, respectively, and the mean diameter was 120.4 nm from three batches. In vitro release showed that the release of BF from (FA+Tf) BF-LPs was slow with burst effects at an early stage. In vitro cytotoxicity assay showed that (FA+Tf) BF-LPs had a superior antiproliferative effect on A549 cells. An in vivo imaging study indicated that (FA+Tf) BF-LPs had obvious targeting characteristics on subcutaneous tumor, with the potential to actively deliver drugs to tumor tissues. In terms of the in vivo antitumor activity, (FA+Tf) BF-LPs treated mice showed a significantly suppressed tumor growth and no systemic toxicity in the body.

Conclusion

Through this study, it was found that the Tf and FA co-modified BF could be a very promising lung target preparation.

Confirmation of high-throughput screening data and novel mechanistic insights into VDR-xenobiotic interactions by orthogonal assays

High throughput screening (HTS) programs have demonstrated that the Vitamin D receptor (VDR) is activated and/or antagonized by a wide range of structurally diverse chemicals. In this study, we examined the Tox21 qHTS data set generated against VDR for reproducibility and concordance and elucidated functional insights into VDR-xenobiotic interactions. Twenty-one potential VDR agonists and 19 VDR antagonists were identified from a subset of >400 compounds with putative VDR activity and examined for VDR functionality utilizing select orthogonal assays. Transient transactivation assay (TT) using a human VDR plasmid and Cyp24 luciferase reporter construct revealed 20/21 active VDR agonists and 18/19 active VDR antagonists. Mammalian-2-hybrid assay (M2H) was then used to evaluate VDR interactions with co-activators and co-regulators. With the exception of a select few compounds, VDR agonists exhibited significant recruitment of co-regulators and co-activators whereas antagonists exhibited considerable attenuation of recruitment by VDR. A unique set of compounds exhibiting synergistic activity in antagonist mode and no activity in agonist mode was identified. Cheminformatics modeling of VDR-ligand interactions were conducted and revealed selective ligand VDR interaction. Overall, data emphasizes the molecular complexity of ligand-mediated interactions with VDR and suggest that VDR transactivation may be a target site of action for diverse xenobiotics.

Bufalin-loaded bovine serum albumin nanoparticles demonstrated improved anti-tumor activity against hepatocellular carcinoma: preparation, characterization, pharmacokinetics and tissue distribution

Objective

To prepare and evaluate the liver-targeted drug delivery system of Bufalin with higher liver uptake and stronger antitumor activity against hepatocellular carcinoma.

Methods

Bufalin-loaded bovine serum albumin nanoparticle was prepared by desolvation method, to investigate the in vitro release performance and to evaluate the pharmacokinetic and tissue distribution. The antitumor activity against hepatocellular carcinoma was evaluated in vitro and in vivo, respectively.

Results

The Bufalin-loaded bovine serum albumin nanoparticle with an average particle size of 125.1 nm exhibited a sustained release behavior in vitro. The half-life, blood plasma area under the curve and apparent volume of distribution of Bufalin-loaded bovine serum albumin nanoparticle were significantly higher than that of Bufalin, whereas the clearance rate was lower than Bufalin group. The uptake of liver for Bufalin-loaded bovine serum albumin nanoparticle was 352.045 ± 35.665 ng/g while for Bufalin was 164.465 ± 48.080 ng/g (P < 0.01) at 5 min. The uptake of tumor for Bufalin-loaded bovine serum albumin nanoparticle was significantly higher than that of Bufalin both at 5 min (50.169 ± 11.708 ng/g, 93.415±13.828 ng/g, P < 0.01) and 15 min (43.683 ± 11.499 ng/g, 64.219 ± 17.684 ng/g, P > 0.05). Bufalin-loaded bovine serum albumin nanoparticle and Bufalin have similar antitumor activity in vitro. The tumor inhibition effect of Bufalin-loaded bovine serum albumin nanoparticle was stronger than that of Bufalin alone in vivo.

Conclusion

Bufalin-loaded bovine serum albumin nanoparticle is a promising liver-targeted drug delivery system with higher liver uptake and stronger antitumor activity against hepatocellular carcinoma.

Esterase-responsive polymeric prodrug-based tumor targeting nanoparticles for improved anti-tumor performance against colon cancer

We report on the fabrication of a multifunctional polymeric prodrug covalently linked with an anticancer drug (bufalin, BUF) and tumor-targeting peptide (RGD) and investigate its anticancer performance against colon cancer in mice.

Bufalin Inhibits HCT116 Colon Cancer Cells and Its Orthotopic Xenograft Tumor in Mice Model through Genes Related to Apoptotic and PTEN/AKT Pathways

Aims. To investigate the anticolorectal cancer (CRC) effects of Bufalin, a bioactive polyhydroxysteroid from Venenum Bufonis, using HCT116 human CRC cell and an established orthotopic xenograft model in mice, and to explore the mechanisms of action. Material and Methods. Cultured HCT116 cells or BALB/c mice with orthotopic tumor were treated by Bufalin (positive control: 5-FU). Cell proliferation, apoptosis, and cycling were determined by MTT, Annexin V/PI staining, and flow cytometry, respectively. In mice, tumor inhibition rate and animal survival were calculated. The expressions of PTEN/phosphate-PTEN, AKT/phosphate-AKT, Bad, Bcl-xl, Bax, or Caspase-3 in cells and/or tumors were determined by Western blot or immunohistochemical staining. Results. Bufalin significantly inhibited cell proliferation and induced cell apoptosis and cycle arrest in a dose/time-dependent manner. In the animal model, Bufalin treatment resulted in significant inhibition of tumor growth and prolonged survival. In the Bufalin-treated cultured cells and/or xenograft tumors, the expressions of PTEN, Bad, Bax, and Caspase-3 were significantly increased, while p-AKT and Bcl-xL significantly decreased. Conclusions. Our results indicate that Bufalin inhibit cell proliferation and orthotopic tumor growth by inducing cell apoptosis through the intrinsic apoptotic pathway, which is of pivotal significance in the identification of an anticancer drug that may synergize with Bufalin.

Antitumor effects of traditional Chinese medicine targeting the cellular apoptotic pathway

Defects in apoptosis are common phenomena in many types of cancer and are also a critical step in tumorigenesis. Targeting the apoptotic pathway has been considered an intriguing strategy for cancer therapy. Traditional Chinese medicine (TCM) has been used in the People’s Republic of China for thousands of years, and many of the medicines have been confirmed to be effective in the treatment of a number of tumors. With increasing cancer rates worldwide, the antitumor effects of TCMs have attracted more and more attention globally. Many of the TCMs have been shown to have antitumor activity through multiple targets, and apoptosis pathway-related targets have been extensively studied and defined to be promising. This review focuses on several antitumor TCMs, especially those with clinical efficacy, based on their effects on the apoptotic signaling pathway. The problems with and prospects of development of TCMs as anticancer agents are also presented.

Botanical compounds and their regulation of nuclear receptor action: the case of traditional Chinese medicine

Nuclear receptors (NRs) are major pharmacological targets that allow an access to the mechanisms controlling gene regulation. As such, some NRs were identified as biological targets of active compounds contained in herbal remedies found in traditional medicines. We aim here to review this expanding literature by focusing on the informative articles regarding the mechanisms of action of traditional Chinese medicines (TCMs). We exemplified well-characterized TCM action mediated by NR such as steroid receptors (ER, GR, AR), metabolic receptors (PPAR, LXR, FXR, PXR, CAR) and RXR. We also provided, when possible, examples from other traditional medicines. From these, we draw a parallel between TCMs and phytoestrogens or endocrine disrupting chemicals also acting via NR. We define common principle of action and highlight the potential and limits of those compounds. TCMs, by finely tuning physiological reactions in positive and negative manners, could act, in a subtle but efficient way, on NR sensors and their transcriptional network.

Induced differentiation of human myeloid leukemia cells into M2 macrophages by combined treatment with retinoic acid and 1α,25-dihydroxyvitamin D3

Retinoids and 1α,25-dihydroxyvitamin D₃ (1,25(OH)₂D₃) induce differentiation of myeloid leukemia cells into granulocyte and macrophage lineages, respectively. All-trans retinoic acid (ATRA), which is effective in the treatment of acute promyelocytic leukemia, can induce differentiation of other types of myeloid leukemia cells, and combined treatment with retinoid and 1,25(OH)₂D₃ effectively enhances the differentiation of leukemia cells into macrophage-like cells. Recent work has classified macrophages into M1 and M2 types. In this study, we investigated the effect of combined treatment with retinoid and 1,25(OH)₂D₃ on differentiation of myeloid leukemia THP-1 and HL60 cells. 9-cis Retinoic acid (9cRA) plus 1,25(OH)₂D₃ inhibited proliferation of THP-1 and HL60 cells and increased myeloid differentiation markers including nitroblue tetrazolium reducing activity and expression of CD14 and CD11b. ATRA and the synthetic retinoic acid receptor agonist Am80 exhibited similar effects in combination with 1,25(OH)₂D₃ but less effectively than 9cRA, while the retinoid X receptor agonist HX630 was not effective. 9cRA plus 1,25(OH)₂D₃ effectively increased expression of M2 macrophage marker genes, such as CD163, ARG1 and IL10, increased surface CD163 expression, and induced interleukin-10 secretion in myeloid leukemia cells, while 9cRA alone had weaker effects on these phenotypes and 1,25(OH)₂D₃ was not effective. Taken together, our results demonstrate selective induction of M2 macrophage markers in human myeloid leukemia cells by combined treatment with 9cRA and 1,25(OH)₂D₃.

β-Elemene against human lung cancer via up-regulation of P53 protein expression to promote the release of exosome

BACKGROUND

β-Elemene, a novel antitumor plant drug extracted from the traditional Chinese medicinal herb Zedoary, has been shown to be effective against a wide variety of tumors. Recent studies have indicated that β-elemene can inhibit the growth of lung cancer cells; however, the exact mechanism of β-element's action in lung cancer remains largely unknown. In the present study, the antitumor effect of β-elemene on human lung cancer cells and the mechanism involved has been investigated.

METHODS

The inhibitory effects of β-elemene on cell growth were measured by Trypan Blue exclusion and MTT assay. Flow cytometric analysis was used to detect the cells' apoptotic rate. The expression of P53 mRNA and protein were measured by RT-PCR and Western blot analysis, respectively. Exosomes were isolated by differential centrifugation steps and analyzed by electron microscopy and western blotting. P53 knockdown cells were established through transfection with P53 siRNA. To investigate the effect of β-elemene on the tumor growth in vivo, a Xenograft nude mouse model was established by injecting the A549 cells into the back of a BABL/c nude mouse.

RESULTS

β-Elemene markedly inhibited growth and induced apoptosis in lung cancer cells. The levels of the anti-apoptotic genes Bcl-2 and Bcl-xl in A549 cells decreased, while expression of P53 and production of exosomes increased after β-elemene treatment. Further siRNA studies suggested that the effect of β-elemene on A549 cells is dependent on P53 expression. Exosomes derived from A549 cultured with a human lung cancer cell line exhibited decreased tumor cell proliferation. The in vivo study demonstrated that β-elemene inhibited tumor growth, and up-regulated the expression of P53 and the release of exosome.

CONCLUSION

Our results demonstrated β-elemene acts on lung cancer cells in a P53 dependent manner and exosomes are involved in the regulation of cell proliferation.

Preparation of bufalin-loaded pluronic polyetherimide nanoparticles, cellular uptake, distribution, and effect on colorectal cancer

A large number of studies have shown that bufalin can have a significant antitumor effect in a variety of tumors. However, because of toxicity, insolubility in water, fast metabolism, short half-life, and other shortcomings, its application is limited in cancer therapy. In this study, we explored the anti-metastatic role of bufalin-loaded pluronic polyetherimide nanoparticles on HCT116 colon cancer-bearing mice. Nanoparticle size, shape, drug loading, encapsulation efficiency, and in vitro drug release were studied. Also, cellular uptake of nanoparticles, in vivo tumor targeting, and tumor metastasis were studied. The nanoparticles had a particle size of about 60 nm and an encapsulation efficiency of 75.71%, by weight. The in vitro release data showed that free bufalin was released faster than bufalin-loaded pluronic polyetherimide nanoparticles, and almost 80% of free bufalin was released after 32 hours. Nanoparticles had an even size distribution, were stable, and had a slow release and a tumor-targeting effect. Bufalin-loaded pluronic polyetherimide nanoparticles can significantly inhibit the growth and metastasis of colorectal cancer.

Bufalin inhibited the growth of human osteosarcoma MG-63 cells via down-regulation of Bcl-2/Bax and triggering of the mitochondrial pathway

Cinobufacini (Huachansu), a Chinese medicine prepared from the skin of Bufo bufo gargarizans Cantor (Bufonidae), has potent anti-tumor activity in vitro and in vivo. However, the molecular mechanism of cell apoptosis induced by Bufalin remains elusive. Here, we investigated the apoptosis in Bufalin-treated human osteosarcoma MG-63 cells. The results showed that Bufalin could inhibit cell proliferation and induce apoptosis in a dose- and time-dependent manner. Further investigation revealed that a disruption of mitochondrial transmembrane potential (MMP) and an up-regulation of reactive oxygen species (ROS) in Bufalin-treated cells. By western blot analysis, we found that the up-regulation of Apaf-1, cleaved PARP, cleaved caspase-3, cleaved caspase-9, and Bax/Bcl-2, varies with different concentration of Bufalin. These protein interactions may play a pivotal role in the regulation of apoptosis. Taken together, these results overall indicate that Bufalin could be used as an effective anti-tumor agent in therapy of osteosarcoma targets the mitochondrial-dependent signaling pathway.

IL6 and IL10 are genetic susceptibility factors of periodontal disease

Background:

Periodontitis is a disease mainly caused by a chronic infection of tissues that support the teeth. Several factors, such as diabetes, smoking and oral care, as well as genetic susceptibility can influence both the risk to develop periodontitis and its progression. The aim of the investigation was to test whether alleles of candidate genes were associated with periodontitis.

Materials and Methods:

A case control study was performed with a cohort of 184 patients with chronic periodontitis and 231 healthy controls from the Italian population. A total of six single nucleotide polymorphisms from five candidate genes, i.e., IL1A, IL1B, IL6, IL10 and vitamin D receptor, were investigated.

Results:

Evidence of association were obtained for rs1800795 mapping in IL6 (P value = 0.01) as well as for the rs1800872 mapping in IL10 (P = 0.04). The rarer variant allele lowered the risk to develop periodontitis at IL6 (Odds Ratio [OR] = 0.69 [95% confidence interval {CI} 0.51-0.93]) and increased the risk at IL10 (OR = 1.38 [95% CI 1.01-1.86]).

Conclusions:

The present investigation indicated that polymorphisms of IL6 and IL10 constitute risk factors for chronic periodontitis, while there was no evidence implicating a specific IL1A or IL1B genotype.

Bufalin Reverses HGF-Induced Resistance to EGFR-TKIs in EGFR Mutant Lung Cancer Cells via Blockage of Met/PI3k/Akt Pathway and Induction of Apoptosis

The epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs), such as gefitinib and erlotinib, have shown promising therapeutic efficacy in nonsmall cell lung cancer (NSCLC) patients harboring epidermal growth factor receptor- (EGFR-) activating mutation. However, the inevitable recurrence resulting from acquired resistance has limited the clinical improvement in therapy outcomes. Many studies demonstrate that hepatocyte growth factor- (HGF-) Met axis plays an important role in tumor progression and drug sensitivity. HGF may induce resistance to EGFR-TKIs in EGFR mutant lung cancer cells by Met/PI3K/Akt signaling. The purpose of this study was to determine whether bufalin, a major bioactive component of Venenum Bufonis, could reverse HGF-induced resistance to reversible and irreversible EGFR-TKIs in mutant lung cancer cells PC-9, HCC827, and H1975. Our studies showed that bufalin could reverse resistance to reversible and irreversible EGFR-TKIs induced by exogenous HGF in EGFR mutant lung cancer cells by inhibiting the Met/PI3K/Akt pathway and inducing death signaling. These results suggested that bufalin might have a potential to overcome HGF-induced resistance to molecular-targeted drugs for lung cancer.

Novel vitamin D compounds and skin cancer prevention

As skin cancer is one of the most costly health issues in many countries, particularly in Australia, the possibility that vitamin D compounds might contribute to prevention of this disease is becoming increasingly more attractive to researchers and health communities. In this article, important epidemiologic, mechanistic and experimental data supporting the chemopreventive potential of several vitamin D-related compounds are explored. Evidence of photoprotection by the active hormone, 1α,25dihydroxyvitamin D3, as well as a derivative of an over-irradiation product, lumisterol, a fluorinated analog and bufalin, a potential vitamin D-like compound, are provided. The aim of this article is to understand how vitamin D compounds contribute to UV adaptation and potentially, skin cancer prevention.

Bufalin-loaded mPEG-PLGA-PLL-cRGD nanoparticles: preparation, cellular uptake, tissue distribution, and anticancer activity

BACKGROUND

Recent studies have shown that bufalin has a good antitumor effect but has high toxicity, poor water solubility, a short half-life, a narrow therapeutic window, and a toxic dose that is close to the therapeutic dose, which all limit its clinical application. This study aimed to determine the targeting efficacy of nanoparticles (NPs) made of methoxy polyethylene glycol (mPEG), polylactic-co-glycolic acid (PLGA), poly-L-lysine (PLL), and cyclic arginine-glycine-aspartic acid (cRGD) loaded with bufalin, ie, bufalin-loaded mPEG-PLGA-PLL-cRGD nanoparticles (BNPs), in SW620 colon cancer-bearing mice.

METHODS

BNPs showed uniform size. The size, shape, zeta potential, drug loading, encapsulation efficiency, and release of these nanoparticles were studied in vitro. The tumor targeting, cellular uptake, and growth-inhibitory effect of BNPs in vivo were tested.

RESULTS

BNPs were of uniform size with an average particle size of 164 ± 84 nm and zeta potential of 2.77 mV. The encapsulation efficiency was 81.7% ± 0.89%, and the drug load was 3.92% ± 0.16%. The results of in vitro cytotoxicity studies showed that although the blank NPs were nontoxic, they enhanced the cytotoxicity of bufalin in BNPs. Drug release experiments showed that the release of the drug was prolonged and sustained. The results of confocal laser scanning microscopy indicated that BNPs could effectively bind to human umbilical vein endothelial cells. In the SW620 xenograft mice model, the BNPs could effectively target the tumor in vivo. The BNPs were significantly more effective than other NPs in preventing tumor growth.

CONCLUSION

BNPs had even size distribution, were stable, and had a slow-releasing and tumor-targeting effect. BNPs significantly inhibited colon cancer growth in vitro and in vivo. As a novel drug carrier system, BNPs are a potentially promising targeting treatment for colon cancer.

Vitamin D receptor activation enhances benzo[a]pyrene metabolism via CYP1A1 expression in macrophages

Benzo[a]pyrene (BaP) activates the aryl hydrocarbon (AHR) and induces the expression of genes involved in xenobiotic metabolism, including CYP1A1. CYP1A1 is involved not only in BaP detoxification but also in metabolic activation, which results in DNA adduct formation. Vitamin D receptor (VDR) belongs to the NR1I subfamily of the nuclear receptor superfamily, which also regulates expression of xenobiotic metabolism genes. We investigated the cross-talk between AHR and VDR signaling pathways and found that 1α,25-dihydroxyvitamin D(3) [1,25(OH)(2)D(3)], a potent physiological VDR agonist, enhanced BaP-induced transcription of CYP1A1 in human monocytic U937 cells and THP-1 cells, breast cancer cells, and kidney epithelium-derived cells. 1,25(OH)(2)D(3) alone did not induce CYP1A1, and 1,25(OH)(2)D(3) plus BaP did not increase CYP1A2 or CYP1B1 mRNA expression in U937 cells. The combination of 1,25(OH)(2)D(3) and BaP increased CYP1A1 protein levels, BaP hydroxylation activity, and BaP-DNA adduct formation in U937 cells and THP-1 cells more effectively than BaP alone. The combined effect of 1,25(OH)(2)D(3) and BaP on CYP1A1 mRNA expression in U937 cells and/or THP-1 cells was inhibited by VDR knockdown, VDR antagonists, and α-naphthoflavone, an AHR antagonist. Electrophoretic mobility shift assays and chromatin immunoprecipitation assays showed that VDR directly bound to an everted repeat (ER) 8 motif in the human CYP1A1 promoter. Thus, CYP1A1 is a novel VDR target gene involved in xenobiotic metabolism. Induction of CYP1A1 by the activation of VDR and AHR may contribute to BaP-mediated toxicity and the physiological function of this enzyme.

Bufalin enhances the antitumor effect of gemcitabine in pancreatic cancer

Bufalin, an active component of the Chinese medicine chan'su, has been reported to have an inhibitory effect on the growth of various types of cancer cells. In the present study, we investigated whether gemcitabine combined with bufalin enhanced the antitumor efficacy in pancreatic cancer. Three pancreatic cancer cell lines (Bxpc-3, Mia PaCa-2 and Panc-1) were treated with gemcitabine and/or bufalin in vitro. The combination treatment demonstrated greater inhibition of cellular growth and apoptosis. The activity of apoptosis signal-regulating kinase 1 (ASK1)/JNK was upregulated in gemcitabine-induced apoptosis when combined with bufalin. We also observed that tumor growth was significantly inhibited by the combination therapy in a tumor-bearing mouse model, and upregulation of ASK1 activity was validated by immunohistochemical staining. These results suggest that bufalin may be a potential chemotherapeutic agent for pancreatic cancer, which could enhance the antitumor efficacy of gemcitabine when used in combination, possibly through the activation of ASK1/JNK.

Cell-Type-Specific Effects of Silibinin on Vitamin D-Induced Differentiation of Acute Myeloid Leukemia Cells Are Associated with Differential Modulation of RXRα Levels

Plant polyphenols have been shown to enhance the differentiation of acute myeloid leukemia (AML) cells induced by the hormonal form of vitamin D(3) (1α,25-dihydroxyvitamin D(3); 1,25D). However, how these agents modulate 1,25D effects in different subtypes of AML cells remains poorly understood. Here, we show that both carnosic acid (CA) and silibinin (SIL) synergistically enhancd 1,25D-induced differentiation of myeloblastic HL60 cells. However, in promonocytic U937 cells, only CA caused potentiation while SIL attenuated 1,25D effect. The enhanced effect of 1,25D+CA was accompanied by increases in both the vitamin D receptor (VDR) and retinoid X receptor alpha (RXRα) protein levels and vitamin D response element (VDRE) transactivation in both cell lines. Similar increases were observed in HL60 cells treated with 1,25D + SIL. In U937 cells, however, SIL inhibited 1,25D-induced VDRE transactivation concomitant with downregulation of RXRα at both transcriptional and posttranscriptional levels. These inhibitory effects correlated with the inability of SIL, with or without 1,25D, to activate the Nrf2/antioxidant response element signaling pathway in U937 cells. These results suggest that opposite effects of SIL on 1,25D-induced differentiation of HL60 and U937 cells may be determined by cell-type-specific signaling and transcriptional responses to this polyphenol resulting in differential modulation of RXRα expression.

1,25-Dihydroxycholecalciferol with low-calcium diet reduces acute rejection in rat lung allotransplantation

OBJECTIVES

The effect of 1,25-dihydroxycholecalciferol (calcitriol, vitamin D3) with a low-calcium diet on the acute lung allograft rejection in a rat unilateral left lung transplantation model was evaluated.

METHODS

Three transplantation groups were studied (n = 5, male Brown-Norway to Fischer F344, 235 ± 15 g body weight): calcitriol and low-calcium diet, low-calcium diet and normal diet. Calcitriol (4 μg/kg/day) was injected intraperitoneally for 5 days, starting from the day of transplantation. In addition, two non-transplantation groups were compared: (n = 3, Brown-Norway) to measure the level of cytokines, and Fischer F344 receiving calcitriol and a low-calcium diet to measure the serum calcium level. The recipients of transplantation were killed on Day 5 post-transplant. The contralateral right main bronchus and the pulmonary artery were occluded for 5 min and blood was drawn for the blood gas analysis, and the grafts were assessed for histology (International Society for Heart and Lung Transplantation 1996/rank scale). Lung levels of interleukin (IL)-2, IL-6, IL-12 and tumour necrosis factor-α (TNF-α) were assessed within the calcitriol and low-calcium diet, low-calcium diet and Brown-Norway groups. The serum calcium level was assessed in the Fischer F344 group. An analysis of variance with Tukey's post hoc test was used to compare the arterial blood oxygen pressure and the lung cytokine expression between groups. A non-parametric Kruskal-Wallis test followed by the Siegel and Castellan post hoc test was used to assess the differences between the groups according to the lung graft rejection grading. Student's paired t-test was used to compare the serum calcium level.

RESULTS

The arterial PaO(2) was significantly higher in the calcitriol and the low-calcium diet groups when compared with low-calcium diet or normal diet groups (356 ± 72 mmHg; P < 0.05 vs other groups). The arterial and bronchial rejection observed in calcitriol and low-calcium diet group was significantly milder than in the low-calcium diet or normal diet groups (A1-2, B1-2; P < 0.05 vs other groups). IL-2 and IL-6 levels were significantly higher in low-calcium diet vs calcitriol and low-calcium diet and Brown-Norway groups. IL-12 and TNF-α did not differ among the groups. There was no significant difference in serum calcium level before and after the treatment in the Fischer F344 group.

CONCLUSIONS

Calcitriol with a low-calcium diet treatment improves lung function, reduces lung allograft acute rejection, decreases IL-2 and IL-6 allograft expression and does not change the serum calcium level significantly.

Attenuation of glomerular filtration barrier damage in adriamycin-induced nephropathic rats with bufalin: an antiproteinuric agent

Proteinuria is an important risk factor for the progression and prognosis of chronic kidney disease. Bufalin, a cardiotonic steroid, has been shown to posses a variety of biological activities including cardiotonic, anaesthetic and antineoplastic activities, and regulate the immune response. This study investigated the effects of bufalin against proteinuria and glomerular filtration barrier damage in rats with adriamycin (ADR)-induced nephropathy. We compared the blood and urine biochemical indices and the histologic and ultrastructure of the glomerulus in ADR rats with and without the intervention of bufalin or prednisone. The transcription, expression and distribution of the podocyte-associated molecules were compared utilising RT-PCR, western blotting and immunohistochemical staining. We found that bufalin reduced the urinary protein excretion and optimised the lipidaemia of the ADR rats. Bufalin alleviated the removal of podocyte foot processes and attenuated the changes in nephrin, podocin and integrin-linked kinase (ILK) stainings in the glomerulus of the ADR rats. Bufalin notably decreased the expression of nephrin and ILK but inhibited the down-regulation of podocin in protein levels on the renal cortex of the ADR rats. Additionally, bufalin inhibited the up-regulation of podocin and ILK in mRNA levels but did not affect nephrin mRNA levels. These results suggest that bufalin could alleviate ADR-induced proteinuria by protecting the glomerular filtration barrier and may be a novel potential therapeutic agent for proteinuria-associated kidney disease.

[Effect of Bufalin on proliferation and apoptosis of human non-small cell lung cancer A549 cell]

背景与目的

蟾蜍灵是从中药蟾酥中提取出来的有效成分，其抗肿瘤作用已经在许多体外肿瘤细胞中得到证实，本研究旨在探讨蟾蜍灵对人非小细胞肺癌细胞的增殖抑制、诱导凋亡作用及其机制。

方法

采用MTT法测定细胞活力，绘制细胞增殖抑制曲线；瑞氏-吉姆萨染色法观察细胞形态学的变化；流式细胞仪通过PI染色进行细胞周期分析及凋亡判定；Western blot法检测Livin及Caspase-3蛋白的表达。

结果

蟾蜍灵以时间、剂量依赖方式抑制A549细胞增殖，48 h、72 h及96 h抑制细胞增殖50%的药物浓度（half maximal inhibitory concentration, IC₅₀）分别为（56.14±6.72）nmol/L、（15.57±4.28）nmol/L及（7.39±4.16）nmol/L；蟾蜍灵能诱导肺癌细胞凋亡，形态学表现为出现凋亡小体及流式细胞仪检测到的亚二倍体凋亡峰，凋亡率与对照组比较差异有统计学意义（均P < 0.01）；蟾蜍灵诱导细胞凋亡过程中，下调Livin蛋白表达（P < 0.01），同时活化Caspase-3蛋白。

结论

蟾蜍灵能够抑制肺癌细胞A549的增殖，并诱导其凋亡；抑制凋亡抑制蛋白Livin的活性及活化Caspase-3可能在其抑癌机制中发挥重要作用。

Vitamin D3-driven signals for myeloid cell differentiation--implications for differentiation therapy

Primitive myeloid leukemic cell lines can be driven to differentiate to monocyte-like cells by 1alpha,25-dihydroxyvitamin D(3) (1,25(OH)(2)D(3)), and, therefore, 1,25(OH)(2)D(3) may be useful in differentiation therapy of myeloid leukemia and myelodysplastic syndromes (MDS). Recent studies have provided important insights into the mechanism of 1,25(OH)(2)D(3)-stimulated differentiation. For myeloid progenitors to complete monocytic differentiation a complex network of intracellular signals has to be activated and/or inactivated in a precise temporal and spatial pattern. 1,25(OH)(2)D(3) achieves this change to the 'signaling landscape' by (i) direct genomic modulation of the level of expression of key regulators of cell signaling and differentiation pathways, and (ii) activation of intracellular signaling pathways. An improved understanding of the mode of action of 1,25(OH)(2)D(3) is facilitating the development of new therapeutic regimens.