Vitamin D receptor suppresses proliferation and metastasis in renal cell carcinoma cell lines via regulating the expression of the epithelial Ca2+ channel TRPV5

The Role of the Gut Microbiome in Neuroinflammation and Chemotherapy-Induced Peripheral Neuropathy

Chemotherapy-induced peripheral neuropathy (CIPN) is one of the most debilitating adverse effects caused by chemotherapy drugs such as paclitaxel, oxaliplatin and vincristine. It is untreatable and often leads to the discontinuation of cancer therapy and a decrease in the quality of life of cancer patients. It is well-established that neuroinflammation and the activation of immune and glial cells are among the major drivers of CIPN. However, these processes are still poorly understood, and while many chemotherapy drugs alone can drive the activation of these cells and consequent neuroinflammation, it remains elusive to what extent the gut microbiome influences these processes. In this review, we focus on the peripheral mechanisms driving CIPN, and we address the bidirectional pathways by which the gut microbiome communicates with the immune and nervous systems. Additionally, we critically evaluate literature addressing how chemotherapy-induced dysbiosis and the consequent imbalance in bacterial products may contribute to the activation of immune and glial cells, both of which drive neuroinflammation and possibly CIPN development, and how we could use this knowledge for the development of effective treatment strategies.

Genomic and non-genomic action of vitamin D on ion channels - Targeting mitochondria

Recent studies revealed that mitochondria are not only a place of vitamin D3 metabolism but also direct or indirect targets of its activities. This review summarizes current knowledge on the regulation of ion channels from plasma and mitochondrial membranes by the active form of vitamin D3 (1,25(OH)2D3). 1,25(OH)2D3, is a naturally occurring hormone with pleiotropic activities; implicated in the modulation of cell differentiation, and proliferation and in the prevention of various diseases, including cancer. Many experimental data indicate that 1,25(OH)2D3 deficiency induces ionic remodeling and 1,25(OH)2D3 regulates the activity of multiple ion channels. There are two main theories on how 1,25(OH)2D3 can modify the function of ion channels. First, describes the involvement of genomic pathways of response to 1,25(OH)2D3 in the regulation of the expression of the genes encoding channels, their auxiliary subunits, or additional regulators. Interestingly, intracellular ion channels, like mitochondrial, are encoded by the same genes as plasma membrane channels. Therefore, the comprehensive genomic regulation of the channels from these two different cellular compartments we analyzed using a bioinformatic approach. The second theory explores non-genomic pathways of vitamin D3 activities. It was shown, that 1,25(OH)2D3 indirectly regulates enzymes that impact ion channels, change membrane physical properties, or directly bind to channel proteins. In this article, the involvement of genomic and non-genomic pathways regulated by 1,25(OH)2D3 in the modulation of the levels and activity of plasma membrane and mitochondrial ion channels was investigated by an extensive review of the literature and analysis of the transcriptomic data using bioinformatics.

Role of TRP channels in carcinogenesis and metastasis: Pathophysiology and regulation by non-coding RNAs

In 2021, David Julius and Ardem Patapoutian received Nobel Prize in Physiology or Medicine for their ground-breaking discoveries in the functional characterization of receptors for temperature and touch. Transient receptor potential (TRP) channels have captivated tremendous appreciation as promising drug targets over the past few years because of central involvement in different cancers. Based on the insights gleaned from decades of high-quality research, basic and clinical scientists have unveiled how Transient receptor potential channels regulated cancer onset and progression. Pioneering studies have sparked renewed interest and researchers have started to scratch the surface of mechanistic role of these channels in wide variety of cancers. In this review we have attempted to provide a summary of most recent updates and advancements made in the biology of these channels in context of cancers. We have partitioned this review into different subsections on the basis of emerging evidence about characteristically distinct role of TRPV (TRPV1, TRPV5), TRPM (TRPM3, TRPM7) and TRPC in cancers. Regulation of TRP channels by non-coding RNAs is also a very exciting area of research which will be helpful in developing a sharper understanding of the multi-step aspects of cancers.

Intracellular Helix-Loop-Helix Domain Modulates Inactivation Kinetics of Mammalian TRPV5 and TRPV6 Channels

TRPV5 and TRPV6 are calcium-selective ion channels expressed at the apical membrane of epithelial cells. Important for systemic calcium (Ca²⁺) homeostasis, these channels are considered gatekeepers of this cation transcellular transport. Intracellular Ca²⁺ exerts a negative control over the activity of these channels by promoting inactivation. TRPV5 and TRPV6 inactivation has been divided into fast and slow phases based on their kinetics. While slow inactivation is common to both channels, fast inactivation is characteristic of TRPV6. It has been proposed that the fast phase depends on Ca²⁺ binding and that the slow phase depends on the binding of the Ca²⁺/Calmodulin complex to the internal gate of the channels. Here, by means of structural analyses, site-directed mutagenesis, electrophysiology, and molecular dynamic simulations, we identified a specific set of amino acids and interactions that determine the inactivation kinetics of mammalian TRPV5 and TRPV6 channels. We propose that the association between the intracellular helix-loop-helix (HLH) domain and the TRP domain helix (TDh) favors the faster inactivation kinetics observed in mammalian TRPV6 channels.

Nongenomic Activities of Vitamin D

Vitamin D shows a variety of pleiotropic activities which cannot be fully explained by the stimulation of classic pathway- and vitamin D receptor (VDR)-dependent transcriptional modulation. Thus, existence of rapid and nongenomic responses to vitamin D was suggested. An active form of vitamin D (calcitriol, 1,25(OH)₂D₃) is an essential regulator of calcium-phosphate homeostasis, and this process is tightly regulated by VDR genomic activity. However, it seems that early in evolution, the production of secosteroids (vitamin-D-like steroids) and their subsequent photodegradation served as a protective mechanism against ultraviolet radiation and oxidative stress. Consequently, direct cell-protective activities of vitamin D were proven. Furthermore, calcitriol triggers rapid calcium influx through epithelia and its uptake by a variety of cells. Subsequently, protein disulfide-isomerase A3 (PDIA3) was described as a membrane vitamin D receptor responsible for rapid nongenomic responses. Vitamin D was also found to stimulate a release of secondary massagers and modulate several intracellular processes-including cell cycle, proliferation, or immune responses-through wingless (WNT), sonic hedgehog (SSH), STAT1-3, or NF-kappaB pathways. Megalin and its coreceptor, cubilin, facilitate the import of vitamin D complex with vitamin-D-binding protein (DBP), and its involvement in rapid membrane responses was suggested. Vitamin D also directly and indirectly influences mitochondrial function, including fusion-fission, energy production, mitochondrial membrane potential, activity of ion channels, and apoptosis. Although mechanisms of the nongenomic responses to vitamin D are still not fully understood, in this review, their impact on physiology, pathology, and potential clinical applications will be discussed.

Bone Metastases of Diverse Primary Origin Frequently Express the VDR (Vitamin D Receptor) and CYP24A1

Active vitamin D (1,25(OH)2D3) is known to exert direct anti-cancer actions on various malignant tissues through binding to the vitamin D receptor (VDR). These effects have been demonstrated in breast, prostate, renal and thyroid cancers, which all have a high propensity to metastasise to bone. In addition, there is evidence that vitamin D catabolism via 24-hydroxylase (CYP24A1) is altered in tumour cells, thus, reducing local active vitamin D levels in cancer cells. The aim of this study was to assess VDR and CYP24A1 expression in various types of bone metastases by using immunohistochemistry. Overall, a high total VDR protein expression was detected in 59% of cases (39/66). There was a non-significant trend of high-grade tumours towards the low nuclear VDR expression (p = 0.07). Notably, patients with further distant metastases had a reduced nuclear VDR expression (p = 0.03). Furthermore, a high CYP24A1 expression was detected in 59% (39/66) of bone metastases. There was a significant positive correlation between nuclear VDR and CYP24A1 expression (p = 0.001). Collectively, the VDR and CYP24A1 were widely expressed in a multitude of bone metastases, pointing to a potential role of vitamin D signalling in cancer progression. This is of high clinical relevance, as vitamin D deficiency is frequent in patients with bone metastases.

Multi-Omics Analysis of the Prognosis and Biological Function for TRPV Channel Family in Clear Cell Renal Cell Carcinoma

Background

The transient receptor potential vanilloid (TRPV) channels family, TRPV1-6, has been identified to profoundly affect a wide spectrum of pathological processes in various cancers. However, the biological function and prognostic value of TRPVs in clear cell renal cell carcinoma (ccRCC) are still largely unknown.

Methods

We obtained the gene expression data and clinical information of 539 ccRCC patients from The Cancer Genome Atlas (TCGA) database. A series of databases were used for data processing and visualization, including GEPIA, GeneMANIA, MethSurv, GSCA, TIMER, and starBase databases.

Results

The mRNA expression of TRPV2/3 was upregulated while the expression of TRPV5/6 was downregulated in ccRCC tumor tissues. TRPV family members in ccRCC were rarely mutated (nearly 7 frequencies). The ROC curve showed that TRPV2/5/6 had a high diagnostic ability in discriminating ccRCC from the control samples (AUC>0.9). Higher levels of TRPV3 expression were associated with poor prognosis of ccRCC patients, while higher expression of TRPV4 was associated with favorable prognosis. The expression of TRPV3 in normal and ccRCC tissues was validated by Immunohistochemistry, and its expression was remarkably related to high histologic grade and advanced stage. Besides, TRPV3 exhibit a reduction of DNA methylation level with tumor progression, and 12 CpGs of TRPV3 were associated with a significant prognosis. In addition, TRPV3 expression was significantly associated with the accumulation of several tumor-infiltrating immune cells, especially regulatory T cells. Furthermore, high levels of TRPV3 induced the expression of immune checkpoints such as LAG3, CTLA4, PDCD1, and TIGIT. Finally, we predicted a key SNHG3/AL513497.1-miR-10b-5p-TRPV3 axis linking to carcinogenesis and progression of ccRCC.

Conclusion

Our study may uncover TRPV channels–associated molecular mechanisms involved in the tumorigenesis and progression of ccRCC. TRPV family members might be diagnosed and prognostic markers and potential therapeutic targets for ccRCC patients.

Integrative analysis of TRPV family to prognosis and immune infiltration in renal clear cell carcinoma

The transient receptor potential vanilloid (TRPV) family has been preliminarily discovered to play an important role in various cancers, including clear cell renal cell carcinoma (ccRCC), which is closely associated with immune infiltration. However, the expression and prognosis of TRPV family and tumor-infiltrating immune cells in ccRCC are obscure. This study aimed to explore the prognostic and therapeutic value of the TRPV family expression in ccRCC from the perspective of bioinformatics. We analyzed the transcriptome and clinical data of kidney renal clear cell carcinoma (KIRC) from The Cancer Genome Atlas (TCGA) database. A clustering analysis and immune infiltration analysis were conducted to investigate the influence of the TRPV family genes on ccRCC. Our study found that the TRPV family is an excellent prognostic stratification for ccRCC. Among them, TRPV3 is the most significant prognostic marker of ccRCC. In addition, we performed a drug sensitivity analysis to identify the drugs with the strongest association with TRPV3. As a result, the TRPV family, particularly TRPV3, can act as a prognostic biomarker in ccRCC to determine prognosis and levels of immune infiltration.

DLK2 Acts as a Potential Prognostic Biomarker for Clear Cell Renal Cell Carcinoma Based on Bioinformatics Analysis

Clear cell renal cell carcinoma (ccRCC) is the most common RCC subtype with a high mortality. It has been reported that delta-like 1 homologue (DLK1) participates in the tumor microenvironmental remodeling of ccRCC, but the relationship between delta-like 2 homologue (DLK2, a DLK1 homologue) and ccRCC is still unclear. Thus, this study aims to investigate the role of DLK2 in the biological function and disease prognosis of ccRCC using bioinformatics analysis. The TNMplot database showed that DLK2 was upregulated in ccRCC tissues. From the UALCAN analysis, the overexpression of DLK2 was associated with advanced stage and high grade in ccRCC. Moreover, the Kaplan-Meier plotter (KM Plotter) database showed that DLK2 upregulation was associated with poor survival outcome in ccRCC. By the LinkedOmics analysis, DLK2 signaling may participated in the modulation of ccRCC extracellular matrix (ECM), cell metabolism, ribosome biogenesis, TGF-β signaling and Notch pathway. Besides, Tumor Immune Estimation Resource (TIMER) analysis showed that the macrophage and CD8⁺ T cell infiltrations were associated with good prognosis in ccRCC patients. Finally, DLK2 overexpression was associated with the reduced macrophage recruitments and the M1–M2 polarization of macrophage in ccRCC tissues. Together, DLK2 may acts as a novel biomarker, even therapeutic target in ccRCC. However, this study lacks experimental validation, and further studies are required to support this viewpoint.

KMT2D loss drives aggressive tumor phenotypes in cutaneous squamous cell carcinoma

Cutaneous squamous cell carcinoma (cSCC) is the second most lethal skin cancer. Due to ultraviolet light-induced damage, cSCCs have a high mutation rate, but some genes are more frequently mutated in aggressive cSCCs. Lysine-specific histone methyltransferase 2D (KMT2D) has a two-fold higher mutation frequency in metastatic cSCCs relative to primary non-metastatic associated cSCCs. The role of KMT2D in more aggressive phenotypes in cSCC is uncharacterized. Studies of other tumor types suggest that KMT2D acts to suppress tumor development. To determine whether KMT2D loss has an impact on tumor characteristics, we disrupted KMT2D in a cSCC cell line using CRISPR-cas9 and performed phenotypic analyses. KMT2D loss modestly increased cell proliferation and colony formation (1.4- and 1.6-fold respectively). Cells lacking KMT2D showed increased rates of migration and faster cell cycle progression. In xenograft models, tumors with KMT2D loss showed slight increases in mitotic indices. Collectively, these findings suggest that KMT2D loss-of-function mutations may promote more aggressive and invasive behaviors in cSCC, suggesting that KMT2D-related pathways could be targets for cancer therapies. Future studies to determine the downstream genes and mechanism of phenotypic effect are needed.

A novel role of TCAIM: suppressing renal carcinoma growth and enhancing its sensitivity to sunitinib

Renal carcinoma is a common malignancy for which the underlying molecular mechanisms warrant further investigation. T cell activation inhibitor mitochondrial (TCAIM), a mitochondrial protein, was found to be expressed to a low extent in renal carcinoma specimens. However, its role in carcinomas remains unclear. In the present study, the role of TCAIM in renal carcinoma was explored through loss-of-function and gain-of-function experiments. Here, we showed that TCAIM delayed the growth of renal carcinoma cells both in vitro and in vivo by modulating their cell cycle progress. Additionally, TCAIM also enhanced their sensitivity to sunitinib by aggravating apoptosis. Furthermore, TCAIM also decreased the adhesion and migration of renal carcinoma cells. Moreover, the transcription of TCAIM was regulated by vitamin D receptor, which acts as a transcriptional factor. To identify the pathways regulated by TCAIM, 425 unique proteins bound to TCAIM were pulled down through co-immunoprecipitation and analyzed by mass spectrometry followed by Gene Ontology analysis and Kyoto Encyclopedia of Genes and Genomes analysis. In summary, the present study reveals a tumor-suppressor role of TCAIM in renal carcinoma cells, as well as its upstream regulation and downstream potential mechanisms. Our study provides theoretical bases and novel insights with respect to the development of new therapeutic strategies for the treatment of renal carcinoma.

miR-103a-3p Silencing Ameliorates Calcium Oxalate Deposition in Rat Kidney by Activating the UMOD/TRPV5 Axis

Maintaining the balance of calcium (Ca2+) metabolism in the kidney is crucial in preventing the formation of kidney stones. Functionally, the microRNA (miRNA) participating in this process needs to be unveiled. We induced NRK-52E cell injury by oxalate treatment. The role of transient receptor potential cation channel subfamily V member 5 (TRPV5) in oxalate-induced cells was studied by TRPV5 overexpression transfection, qRT-PCR, Western blot, MTT, and crystal adhesion detection. After identifying uromodulin (UMOD) expression in injured cells, we confirmed the interaction between TRPV5 and UMOD by coimmunoprecipitation (CoIP) and cell-surface biotinylation assays. The validation of UMOD-regulating TRPV5 in viability, crystal adhesion, and Ca2+ concentration of oxalate-induced cells was performed. Bioinformatics analysis and luciferase assay were used to identify the miRNA-targeting UMOD. The role of the miR-103a-3p-regulating UMOD/TRPV5 axis was detected by rescue experiments. We constructed a rat model with treatment of ethylene glycol (EG) to investigate the miR-103a-3p/UMOD/TRPV5 axis in vivo by hematoxylin-eosin (H&E) staining, Western blot, and immunohistochemistry (IHC). Upregulation of TRPV5 protected NRK-52E cells from oxalate-induced injury by enhancing cell viability and inhibiting CaOx adhesion. UMOD was depleted in oxalate-induced cells and positively interacted with TRPV5. UMOD silencing reversed the effect of TRPV overexpression on oxalate-induced cells. miR-103a-3p targeted UMOD and was mediated in the regulation of the UMOD/TRPV5 axis in oxalate-induced cells. Downregulating miR-103a-3p mitigated EG-induced CaOx deposition in kidney tissues in vivo by activating the UMOD/TRPV5 axis. miR-103a-3p silencing ameliorated CaOx deposition in the rat kidney by activating the UMOD/TRPV5 axis.

Mitochondrial potassium channels: A novel calcitriol target

BACKGROUND

Calcitriol (an active metabolite of vitamin D) modulates the expression of hundreds of human genes by activation of the vitamin D nuclear receptor (VDR). However, VDR-mediated transcriptional modulation does not fully explain various phenotypic effects of calcitriol. Recently a fast non-genomic response to vitamin D has been described, and it seems that mitochondria are one of the targets of calcitriol. These non-classical calcitriol targets open up a new area of research with potential clinical applications. The goal of our study was to ascertain whether calcitriol can modulate mitochondrial function through regulation of the potassium channels present in the inner mitochondrial membrane.

METHODS

The effects of calcitriol on the potassium ion current were measured using the patch-clamp method modified for the inner mitochondrial membrane. Molecular docking experiments were conducted in the Autodock4 program. Additionally, changes in gene expression were investigated by qPCR, and transcription factor binding sites were analyzed in the CiiiDER program.

RESULTS

For the first time, our results indicate that calcitriol directly affects the activity of the mitochondrial large-conductance Ca²⁺-regulated potassium channel (mitoBK_Ca) from the human astrocytoma (U-87 MG) cell line but not the mitochondrial calcium-independent two-pore domain potassium channel (mitoTASK-3) from human keratinocytes (HaCaT). The open probability of the mitoBK_Ca channel in high calcium conditions decreased after calcitriol treatment and the opposite effect was observed in low calcium conditions. Moreover, using the AutoDock4 program we predicted the binding poses of calcitriol to the calcium-bound BK_Ca channel and identified amino acids interacting with the calcitriol molecule. Additionally, we found that calcitriol influences the expression of genes encoding potassium channels. Such a dual, genomic and non-genomic action explains the pleiotropic activity of calcitriol.

CONCLUSIONS

Calcitriol can regulate the mitochondrial large-conductance calcium-regulated potassium channel. Our data open a new chapter in the study of non-genomic responses to vitamin D with potential implications for mitochondrial bioenergetics and cytoprotective mechanisms.

Advances in the study of cancer metastasis and calcium signaling as potential therapeutic targets

Metastasis is still the primary cause of cancer-related mortality. However, the underlying mechanisms of cancer metastasis are not yet fully understood. Currently, the epithelial-mesenchymal transition, metabolic remodeling, cancer cell intercommunication and the tumor microenvironment including diverse stromal cells, are reported to affect the metastatic process of cancer cells. Calcium ions (Ca²⁺) are ubiquitous second messengers that manipulate cancer metastasis by affecting signaling pathways. Diverse transporter/pump/channel-mediated Ca²⁺ currents form Ca²⁺ oscillations that can be decoded by Ca²⁺-binding proteins, which are promising prognostic biomarkers and therapeutic targets of cancer metastasis. This paper presents a review of the advances in research on the mechanisms underlying cancer metastasis and the roles of Ca²⁺-related signals in these events.

MiR-125b promotes migration and invasion by targeting the vitamin D receptor in renal cell carcinoma

Purpose: To investigate the expression of miR-125b and vitamin D receptor (VDR) in renal cell carcinoma (RCC) and assess the biological function of miR-125b in RCC. Methods: We used quantitative real-time polymerase chain reaction (RT-PCR) to detect the expression of nucleic acids and western blotting to analyze the protein abundance in RCC cell lines. MiR-125b mimic and inhibitor were employed to investigate the function and behavior of miR-125b in RCC cell lines. The relationship between miR-125 and VDR was verified using luciferase assays. Results: Overexpression of miR-125b promoted migration and invasion and prevent cell apoptosis in ACHN cells. In contrast, miR-125b deficiency suppressed migration and invasion and induced cell apoptosis in 786-O cells. Luciferase assays indicated the interaction between miR-125b and VDR. In collected samples, miR-125b was significantly higher in RCC tissues and negatively correlated to VDR (r=-0.444, p=0.04). Conclusion: MiR-125b displays an oncogene profile in RCC, patients with high expression of miR-125b should be a more frequent follow-up. MiR-125B may be a potential therapeutic target for RCC.

Protective Effect of Calcitriol on Organ Damage Induced by 5-Fluorouracil Treatment

Chemotherapy is a major therapeutic strategy for patients with cancer. Owing to the severe inflammatory response of chemotherapy, patients experience extreme discomfort during treatment, and this may interrupt treatment completion. The vitamin D3 has a role in anti-inflammation, but no study has explored whether vitamin D3 has beneficial effects on patients undergoing chemotherapy. In this study, we investigated the effect of calcitriol (Vit-D) on inflammatory responses during 5-fluorouracil (5-FU) treatment. Rats were divided into five groups and treated with 1:1 dilution of 5-FU with equal amount of 0.9% saline, 1:3 dilution of 5-FU with 0.9% saline threefold dilution, 5-FU, Vit-D, or 5-FU + Vit-D. A single dose of 15 mg/kg of 5-FU was intravenously administered for 4 h, and the blood biochemical substances and inflammatory cytokines were assessed after the intervention. The 5-FU group had higher AST, ALT, LDH, and CPK levels than those in the 5-FU + Vit-D group. The 5-FU + Vit-D group had a lower TNF-α value than the 5-FU. The IL-6 levels in the 5-FU + Vit-D group were also significantly lower than those in 5-FU. Calcitriol administration during 5-FU therapy can alleviate the production of inflammatory cytokines and liver damage.

Ion Channel Regulation by Sex Steroid Hormones and Vitamin D in Cancer: A Potential Opportunity for Cancer Diagnosis and Therapy

Many ion channels are involved in tumor development, promoting cancer cell proliferation, migration, invasion, and survival. Accordingly, some of them have been suggested as tumor markers and novel targets for cancer therapy. Some sex steroid hormones (SSH), including estrogens and androgens, favor cancer progression. Meanwhile, other steroid hormones like vitamin D may have anticancer properties. SSH and vitamin D modulate the expression of a number of ion channels in cancer cells from hormone-sensitive tissues, including breast, ovary, prostate, and cervix. Moreover, rapid effects of SSH may be mediated by their direct action on membrane ion channels. Here, we reviewed the SSH and vitamin D regulation of ion channels involved in cancer, and analyzed the potential molecular pathways implicated. In addition, we described the potential clinical use of ion channels in cancer diagnosis and therapy, taking advantage of their regulation by SSH and vitamin D. Since SSH are considered risk factors for different types of cancer, and ion channels play important roles in tumor progression, the regulation of ion channels by SSH and vitamin D may represent a potential opportunity for early cancer diagnosis and therapeutic approaches in SSH and vitamin D sensitive tumors.

Transient receptor potential ion-channel subfamily V member 4: a potential target for cancer treatment

The transient receptor potential ion-channel superfamily consists of nonselective cation channels located mostly on the plasma membranes of numerous animal cell types, which are closely related to sensory information transmission (e.g., vision, pain, and temperature perception), as well as regulation of intracellular Ca2+ balance and physiological activities of growth and development. Transient receptor potential ion channel subfamily V (TRPV) is one of the largest and most diverse subfamilies, including TRPV1-TRPV6 involved in the regulation of a variety of cellular functions. TRPV4 can be activated by various physical and chemical stimuli, such as heat, mechanical force, and phorbol ester derivatives participating in the maintenance of normal cellular functions. In recent years, the roles of TRPV4 in cell proliferation, differentiation, apoptosis, and migration have been extensively studied. Its abnormal expression has also been closely related to the onset and progression of multiple tumors, so TRPV4 may be a target for cancer diagnosis and treatment. In this review, we focused on the latest studies concerning the role of TRPV4 in tumorigenesis and the therapeutic potential. As evidenced by the effects on cancerogenesis, TRPV4 is a potential target for anticancer therapy.

Apolipoprotein M could inhibit growth and metastasis of SMMC7721 cells via vitamin D receptor signaling

Objective: Hepatocellular carcinoma (HCC) is one of the most common malignant tumors with high mortality-to-incidence ratios. Apolipoprotein M (ApoM), a member of the apolipoprotein family, is mainly synthesized in the liver, whereas its role in HCC has not been elucidated. Here, we examined the effect of ApoM on the biological behavior of HCC cells and the possible mechanisms. Methods: We used CRISPR/Cas9 technology to knock out ApoM in SMMC7721 cells. Differentially expressed genes before and after ApoM knockout (KO) were analyzed by GeneChip microarrays and confirmed by qRT-PCR. Cell assays of proliferation, apoptosis, migration and invasion were performed in SMMC7721 cells, and the expression of epithelial-mesenchymal transition (EMT) markers was performed by western blot. And we performed functional recovery experiments by overexpressing vitamin D receptor (VDR) in SMMC7721. Results: The ApoM-KO SMMC7721 cell line was successfully constructed using the CRISPR/Cas9 technology. Our results showed that silencing ApoM suppressed apoptosis and promoted proliferation, migration, invasion and EMT of SMMC7721 cells. The microarray data revealed that a total of 1,868 differentially expressed genes were identified, including VDR. The qRT-PCR and western blot verification results demonstrated that knocking out ApoM could significantly reduce the expression of VDR. The functional recovery experiments indicated that VDR overexpression could offset the inhibition of cell apoptosis and the promotion of cell proliferation, migration, invasion and EMT caused by knocking out ApoM in SMMC7721 cells. Conclusion: ApoM could function as a tumor suppressor to inhibit the growth and metastasis of SMMC7721 cells via VDR signaling in HCC.

Astemizole promotes the anti-tumor effect of vitamin D through inhibiting miR-125a-5p-meidated regulation of VDR in HCC

Hepatocellular carcinoma (HCC) accounts for the fifth most common cancer worldwide. Vitamin D and antihistamines have been shown to play an anti-tumor role in various tumors. In the present study, we ought to investigate the synergistic effect of astemizole and Vitamin D in HCC cells. We showed that astemizole enhanced the anti-tumor effect of Vitamin D in HCC both in vitro and in vivo. Astemizole enhanced Vitamin D-induced decrease of cell viability and proliferation, increase of apoptosis, decrease of cell migration and invasion in HCC cells in vitro and decrease of tumor number, mass and incidence in HCC in vivo. Astemizole increased VDR expression both in HCC cells in vitro and in tumor tissues in vivo. Downregulation of VDR significantly inhibited the synergistic effect of Vitamin D and astemizole on HCC cell viability, proliferation, apoptosis, migration and invasion. Bioinformatics analysis identified that miR-125a-5p had a putative binding site in the 3'-UTR of VDR. miR-125a-5p mimics inhibited astemizole-induced increase of VDR and enhancement of the anti-tumor effect of Vitamin D in HCC. Reporter gene assay has confirmed that VDR was regulated by miR-125a-5p. miR-125a-5p inhibitors increased VDR expression and decreased cell viability and proliferation in HCC cells. Moreover, VDR and miR-125a-5p expression in tumor tissues in HCC patients were negatively correlated. We identified that inhibition of miR-125a-5p and subsequent upregulation of VDR was involved in astemizole-induced enhancement of the anti-tumor effect of Vitamin D in HCC. These results highlight the importance of combined treatment of astemizole and Vitamin D and provide novel insights into the role of miR-125a-5p-VDR signaling in HCC.