Machine Learning-Based In Silico Prediction of the Inhibitory Activity of Chemical Substances Against Rat and Human Cytochrome P450s.

The prediction of cytochrome P450 inhibition by a computational (quantitative) structure-activity relationship approach using chemical structure information and machine learning would be useful for toxicity research as a simple and rapid in silico tool. However, there are few in silico models focusing on the species differences between rat and human in the P450s inhibition. This study aimed to establish in silico models to classify chemical substances as inhibitors or non-inhibitors of various rat and human P450s, using only molecular descriptors. Using the in-house test results from our in vitro experiments, we used 326 substances for model construction and internal validation data. Apart from the 326 substances, 60 substances were used as external validation data set. We focused on seven rat P450s (CYP1A1, CYP1A2, CYP2B1, CYP2C6, CYP2D1, CYP2E1, and CYP3A2) and 11 human P450s (CYP1A1, CYP1A2, CYP1B1, CYP2A6, CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP2D6, CYP2E1, and CYP3A4). Most of the models established using XGBoost showed an area under the receiver operating characteristic curve (ROC-AUC) of 0.8 or more in the internal validation. When we set an applicability domain for the models and confirmed their generalization performance through external validation, most of the models showed an ROC-AUC of 0.7 or more. Interestingly, for CYP1A1 and CYP1A2, we discovered that a human P450 inhibitory activity model can predict rat P450 inhibitory activity and vice versa. These models are the first attempts to predict inhibitory activity against a wide variety of P450s in both rats and humans using chemical structure information. Our experimental results and in silico models would be helpful to support information for species similarities and differences in chemical-induced toxicity.

Cancerous Conditions Accelerate the Aging of Skeletal Muscle via Mitochondrial DNA Damage.

Skeletal muscle aging and sarcopenia result in similar changes in the levels of aging markers. However, few studies have examined cancer sarcopenia from the perspective of aging. Therefore, this study investigated aging in cancer sarcopenia and explored its causes in vitro and in vivo. In mouse aging, in vitro cachexia, and mouse cachexia models, skeletal muscles showed similar changes in aging markers including oxidative stress, fibrosis, reduced muscle differentiation potential, and telomere shortening. Furthermore, examination of mitochondrial DNA from skeletal muscle revealed a 5 kb deletion in the major arc; truncation of complexes I, IV, and V in the electron transport chain; and reduced oxidative phosphorylation (OXPHOS). The mouse cachexia model demonstrated high levels of high-mobility group box-1 (HMGB1) and tumor necrosis factor-α (TNFα) in cancer ascites. Continuous administration of neutralizing antibodies against HMGB1 and TNFα in this model reduced oxidative stress and abrogated mitochondrial DNA deletion. These results suggest that in cancer sarcopenia, mitochondrial oxidative stress caused by inflammatory cytokines leads to mitochondrial DNA damage, which in turn leads to decreased OXPHOS and the promotion of aging.

Significance of CD10 for Mucosal Immunomodulation by ß-Casomorphin-7 in Exacerbation of Ulcerative Colitis.

ß-Casomorphin-7 (BCM), a breakdown product of milk ß-casein, exhibits opioid activity. Opioids are known to affect the immune system, but the effects of BCM on ulcerative colitis (UC) are not clear. We examined the effects of BCM on mucosal immunity using a mouse dextran sulfate sodium-induced colitis model and an in vitro CD8+ T cell activation model. Human UC patients were examined to reveal the relationship between CD10 and mucosal immunity. Combined treatment of the colitis model with thiorphan (TOP) inhibited BCM degradation by suppressing CD10 in the intestinal mucosa, activating mouse mucosal CD8, and suppressing CD4 and Treg. In the CD8+ T cell in vitro activation assay using mouse splenocytes, BCM inhibited the oxidative phosphorylation (OXPHOS) of CD8+ T cells and induced the glycolytic pathway, promoting their activation. Conversely, in a culture system, BCM suppressed OXPHOS and decreased defensin α production in IEC6 mouse intestinal epithelial cells. In the mouse model, BCM reduced defensin α and butyrate levels in the colonic mucosa. During the active phase of human ulcerative colitis, the downward regulation of ileal CD10 expression by CpG methylation of the gene promoter was observed, resulting in increased CD8 activation and decreased defensin α and butyrate levels. BCM is a potential aggravating factor for UC and should be considered in the design of dietary therapy. In addition, decreased CD10 expression may serve as an indicator of UC activity and recurrence, but further clinical studies are needed.

Differential Effects of Three Medium-Chain Fatty Acids on Mitochondrial Quality Control and Skeletal Muscle Maturation.

Nutritional interventions are one focus of sarcopenia treatment. As medium-chain fatty acids (MCFAs) are oxidized in the mitochondria and produce energy through oxidative phosphorylation (OXPHOS), they are key parts of nutritional interventions. We investigated the in vitro effects of three types of MCFA, caprylic acid (C8), capric acid (C10), and lauric acid (C12), in skeletal muscle cells. Compared with C10 and C12, C8 promoted mitophagy through the phosphatase and tensin homolog (PTEN)-induced kinase 1-Parkin pathway and increased the expression of peroxisome proliferator-activated receptor gamma coactivator 1-α and dynamin-related protein 1 to reduce mitochondrial oxidative stress and promote OXPHOS. Furthermore, the expression of myogenic differentiation 1 and myosin heavy chain increased in myotubes, thus promoting muscle differentiation and maturation. These results suggest that C8 improves mitochondrial quality and promotes skeletal muscle maturation; in contrast, C10 and C12 poorly promoted mitochondrial quality control and oxidative stress and suppressed energy production. Future animal experiments are required to establish the usefulness of C8 for nutritional interventions for sarcopenia.

Effects of High-Mobility Group Box-1 on Mucosal Immunity and Epithelial Differentiation in Colitic Carcinoma.

Abnormalities in mucosal immunity are involved in the onset and progression of ulcerative colitis (UC), resulting in a high incidence of colorectal cancer (CRC). While high-mobility group box-1 (HMGB1) is overexpressed during colorectal carcinogenesis, its role in UC-related carcinogenesis remains unclear. In the present study, we investigated the role of HMGB1 in UC-related carcinogenesis and sporadic CRC. Both the azoxymethane colon carcinogenesis and dextran sulfate sodium colitis carcinogenesis models demonstrated temporal increases in mucosal HMGB1 levels. Activated CD8+ cells initially increased and then decreased, whereas exhausted CD8+ cells increased. Additionally, we observed increased regulatory CD8+ cells, decreased naïve CD8+ cells, and decreased mucosal epithelial differentiation. In the in vitro study, HMGB1 induced energy reprogramming from oxidative phosphorylation to glycolysis in CD8+ cells and intestinal epithelial cells. Furthermore, in UC dysplasia, UC-related CRC, and hyperplastic mucosa surrounding human sporadic CRC, we found increased mucosal HMGB1, decreased activated CD8+ cells, and suppressed mucosal epithelial differentiation. However, we observed increased activated CD8+ cells in active UC mucosa. These findings indicate that HMGB1 plays an important role in modulating mucosal immunity and epithelial dedifferentiation in both UC-related carcinogenesis and sporadic CRC.

Nuclear MAST4 Suppresses FOXO3 through Interaction with AKT3 and Induces Chemoresistance in Pancreatic Ductal Carcinoma.

Pancreatic ductal adenocarcinoma (PDAC) is highly malignant, with a 5-year survival rate of less than 10%. Furthermore, the acquisition of anticancer drug resistance makes PDAC treatment difficult. We established MIA-GEM cells, a PDAC cell line resistant to gemcitabine (GEM), a first-line anticancer drug, using the human PDAC cell line-MIA-PaCa-2. Microtubule-associated serine/threonine kinase-4 (MAST4) expression was increased in MIA-GEM cells compared with the parent cell line. Through inhibitor screening, dysregulated AKT signaling was identified in MIA-GEM cells with overexpression of AKT3. MAST4 knockdown effectively suppressed AKT3 overexpression, and both MAST4 and AKT3 translocation into the nucleus, phosphorylating forkhead box O3a (FOXO3) in MIA-GEM cells. Modulating FOXO3 target gene expression in these cells inhibited apoptosis while promoting stemness and proliferation. Notably, nuclear MAST4 demonstrated higher expression in GEM-resistant PDAC cases compared with that in the GEM-sensitive cases. Elevated MAST4 expression correlated with a poorer prognosis in PDAC. Consequently, nuclear MAST4 emerges as a potential marker for GEM resistance and poor prognosis, representing a novel therapeutic target for PDAC.

Involvement of Ferroptosis Induction and Oxidative Phosphorylation Inhibition in the Anticancer-Drug-Induced Myocardial Injury: Ameliorative Role of Pterostilbene.

Patients with cancer die from cardiac dysfunction second only to the disease itself. Cardiotoxicity caused by anticancer drugs has been emphasized as a possible cause; however, the details remain unclear. To investigate this mechanism, we treated rat cardiomyoblast H9c2 cells with sunitinib, lapatinib, 5-fluorouracil, and cisplatin to examine their effects. All anticancer drugs increased ROS, lipid peroxide, and iron (II) levels in the mitochondria and decreased glutathione peroxidase-4 levels and the GSH/GSSG ratio. Against this background, mitochondrial iron (II) accumulates through the unregulated expression of haem oxygenase-1 and ferrochelatase. Anticancer-drug-induced cell death was suppressed by N-acetylcysteine, deferoxamine, and ferrostatin, indicating ferroptosis. Anticancer drug treatment impairs mitochondrial DNA and inhibits oxidative phosphorylation in H9c2 cells. Similar results were observed in the hearts of cancer-free rats treated with anticancer drugs in vitro. In contrast, treatment with pterostilbene inhibited the induction of ferroptosis and rescued the energy restriction induced by anticancer drugs both in vitro and in vivo. These findings suggest that induction of ferroptosis and inhibition of oxidative phosphorylation are mechanisms by which anticancer drugs cause myocardial damage. As pterostilbene ameliorates these mechanisms, it is expected to have significant clinical applications.

Association of a single nucleotide polymorphism (rs27434) in the ERAP1 gene with plural tissue weight.

Our study was designed to examine the correlation between single nucleotide polymorphism (SNP) in the endoplasmic reticulum aminopeptidase 1 (ERAP1) gene, specifically focusing on rs27434, and plural tissue weight. We conducted this investigation using autopsy samples from the Japanese population. Blood samples were collected from 178 Japanese subjects who had undergone autopsies in Shimane Prefecture. Genomic DNA was subsequently extracted from these samples. SNP (rs27434, G＞A substitution) was analyzed by polymerase chain reaction (PCR) followed by restriction fragment length polymorphism (RFLP) analysis. In the present study, rs27434 exhibited a statistically significant association with brain weight (g) in both female and male individuals. Among males, rs27434 displayed significant relationships with liver weight (g), and body surface area (m2). In females, rs27434 was significantly related to the length of the appendix. Across both genders, individuals with GA and AA genotypes tended to exhibit higher levels in these respective measurements compared to those with the GG genotype. These results suggest that genetic variant of ERAP1 gene may influence the weight of the organs. To the best of our knowledge, this is the first study investigating the interaction between the association of rs27434 in the ERAP1 gene and data routinely measured at autopsy, such as tissue weight. However, conducting further investigations with larger population samples could provide more comprehensive insights to clarify this issue.

Utility of human cytochrome P450 inhibition data in the assessment of drug-induced liver injury.

Drug-induced liver injury (DILI) is a major cause of drug development discontinuation and drug withdrawal from the market, but there are no golden standard methods for DILI risk evaluation. Since we had found the association between DILI and CYP1A1 or CYP1B1 inhibition, we further evaluated the utility of cytochrome P450 (P450) inhibition assay data for DILI risk evaluation using decision tree analysis.The inhibitory activity of drugs with DILI concern (DILI drugs) and no DILI concern (no-DILI drugs) against 10 human P450s was assessed using recombinant enzymes and luminescent substrates. The drugs were also subjected to cytotoxicity assays and high-content analysis using HepG2 cells. Molecular descriptors were calculated by alvaDesc.Decision tree analysis was performed with the data obtained as variables with or without P450-inhibitory activity to discriminate between DILI drugs and no-DILI drugs. The accuracy was significantly higher when P450-inhibitory activity was included. After the decision tree discrimination, the drugs were further discriminated with the P450-inhibitory activity. The results demonstrated that many false-positive and false-negative drugs were correctly discriminated by using the P450 inhibition data.These results suggest that P450 inhibition assay data are useful for DILI risk evaluation.

Interaction with YAP underlies the species differences between humans and rodents in CAR-dependent hepatocyte proliferation.

Constitutive androstane receptor (CAR), a nuclear receptor predominantly expressed in the liver, is activated by diverse chemicals and induces hepatocyte proliferation and hepatocarcinogenesis in rodents. However, the underlying mechanism responsible for CAR-dependent hepatocyte proliferation remains unclear. Importantly, this phenomenon has not been observed in the human liver. This study aimed to investigate the molecular mechanism underlying CAR-induced hepatocyte proliferation and to explore the species differences in hepatocyte proliferation between humans and rodents. Treatment of mice with the CAR activator TCPOBOP induced hepatocyte proliferation and nuclear accumulation of yes-associated protein (YAP), a known liver cancer inducer. This induction was abolished in CAR-knockout mice. Exogenously expressed YAP in cultured cells was accumulated in the nucleus by the coexpression with mouse CAR but not human CAR. Pull-down analysis of recombinant proteins revealed that mouse CAR interacted with YAP, whereas human CAR did not. Further investigations using YAP deletion mutants identified the WW domain of YAP as essential for interacting with CAR and showed that the PY motif (PPAY) in mouse CAR was crucial for binding to the WW domain, whereas human CAR with its mutated motif (PPAH) failed to interact with YAP. A mouse model harboring the Y150H mutation (PPAY to PPAH) in CAR displayed drastically attenuated TCPOBOP-induced hepatocyte proliferation and nuclear accumulation of YAP. CAR induces the nuclear accumulation of YAP through the PY motif-WW domain interaction to promote hepatocyte proliferation. The absence of this interaction in human CAR contributes to the lack of CAR-dependent hepatocyte proliferation in human livers.

ERVK13-1/miR-873-5p/GNMT Axis Promotes Metastatic Potential in Human Bladder Cancer though Sarcosine Production.

N-methyl-glycine (sarcosine) is known to promote metastatic potential in some cancers; however, its effects on bladder cancer are unclear. T24 cells derived from invasive cancer highly expressed GNMT, and S-adenosyl methionine (SAM) treatment increased sarcosine production, promoting proliferation, invasion, anti-apoptotic survival, sphere formation, and drug resistance. In contrast, RT4 cells derived from non-invasive cancers expressed low GNMT, and SAM treatment did not produce sarcosine and did not promote malignant phenotypes. In T24 cells, the expression of miR-873-5p, which suppresses GNMT expression, was suppressed, and the expression of ERVK13-1, which sponges miR-873-5p, was increased. The growth of subcutaneous tumors, lung metastasis, and intratumoral GNMT expression in SAM-treated nude mice was suppressed in T24 cells with ERVK13-1 knockdown but promoted in RT4 cells treated with miR-873-5p inhibitor. An increase in mouse urinary sarcosine levels was observed to correlate with tumor weight. Immunostaining of 86 human bladder cancer cases showed that GNMT expression was higher in cases with muscle invasion and metastasis. Additionally, urinary sarcosine concentrations increased in cases of muscle invasion. Notably, urinary sarcosine concentration may serve as a marker for muscle invasion in bladder cancer; however, further investigation is necessitated.

Role of creatine shuttle in colorectal cancer cells.

The creatine shuttle translocates the energy generated by oxidative phosphorylation to the cytoplasm via mitochondrial creatine kinase (MTCK) and creatine kinase B (CKB) in the cytoplasm. It is not apparent how the creatine shuttle is related to cancer. Here, we analyzed the expression and function of CKB and MTCK in colorectal cancer (CRC) and investigated the role of the creatine shuttle in CRC. Compared with normal mucosa, 184 CRC tissues had higher levels of CKB and MTCK, and these levels were associated with histological grade, tumor invasion, and distant metastasis. CK inhibitor dinitrofluorobenzene (DNFB) on CRC cell lines HT29 and CT26 inhibited cell proliferation and stemness to less than 2/3 and 1/20 of their control levels, respectively. In this treatment, the production of reactive oxygen species increased, mitochondrial respiration decreased, and mitochondrial volume and membrane potential decreased. In a syngeneic BALB/c mouse model using CT26 cells pretreated with DNFB, peritoneal metastasis was suppressed to 70%. Phosphorylation of EGFR, AKT, and ERK1/2 was inhibited in DNFB-treated tumors. High ATP concentrations prevented EGFR phosphorylation in HT29 cells following DNFB treatment, CKB or MTCK knockdown, and cyclocreatine administration. Despite not being immunoprecipitated, CKB and EGFR were brought closer together by EGF stimulation. These findings imply that blocking the creatine shuttle decreases the energy supply, suppresses oxidative phosphorylation, and blocks ATP delivery to phosphorylation signals, preventing signal transduction. These findings highlight the critical role of the creatine shuttle in cancer cells and suggest a potential new cancer treatment target.

Lauric Acid Overcomes Hypoxia-Induced Gemcitabine Chemoresistance in Pancreatic Ductal Adenocarcinoma.

Although gemcitabine (GEM) is widely used in chemotherapy for pancreatic ductal adenocarcinoma (PDA), drug resistance restricts its clinical effectiveness. To examine the mechanism of GEM resistance, we established two GEM-resistant cell lines from human PDA cells by continuous treatment with GEM and CoCl2-induced chemical hypoxia. One resistant cell line possessed reduced energy production and decreased mitochondrial reactive oxygen species levels, while the other resistant cell line possessed increased stemness. In both cell lines, ethidium bromide-stained mitochondrial DNA levels decreased, suggesting mitochondrial DNA damage. Inhibition of hypoxia-inducible factor-1α in both cell lines did not restore the GEM sensitivity. In contrast, treatment of both cell types with lauric acid (LAA), a medium-chain fatty acid, restored GEM sensitivity. These results suggest that decreased energy production, decreased mitochondrial reactive oxygen species levels, and increased stemness associated with mitochondrial damage caused by GEM lead to GEM resistance, and that hypoxia may promote this process. Furthermore, forced activation of oxidative phosphorylation by LAA could be a tool to overcome GEM resistance. Clinical verification of the effectiveness of LAA in GEM resistance is necessary in the future.

Short Telomere Lesions with Dysplastic Metaplasia Histology May Represent Precancerous Lesions of Helicobacter pylori-Positive Gastric Mucosa.

Gastric cancers are strongly associated with Helicobacter pylori infection, with intestinal metaplasia characterizing the background mucosa in most cases. However, only a subset of intestinal metaplasia cases proceed to carcinogenesis, and the characteristics of high-risk intestinal metaplasia that link it with gastric cancer are still unclear. We examined telomere reduction in five gastrectomy specimens using fluorescence in situ hybridization, and identified areas with localized telomere loss (outside of cancerous lesions), which were designated as short telomere lesions (STLs). Histological analyses indicated that STLs were characteristic of intestinal metaplasia accompanied by nuclear enlargement but lacking structural atypia, which we termed dysplastic metaplasia (DM). A review of gastric biopsy specimens from 587 H. pylori-positive patients revealed 32 cases of DM, 13 of which were classified as high-grade based on the degree of nuclear enlargement. All high-grade DM cases exhibited a telomere volume reduced to less than 60% of that of lymphocytes, increased stemness, and telomerase reverse transcriptase (TERT) expression. Two patients (15%) exhibited low levels of p53 nuclear retention. After a 10-year follow-up, 7 (54%) of the high-grade DM cases had progressed to gastric cancer. These results suggest that DM is characterized by telomere shortening, TERT expression, and stem cell proliferation, and high-grade DM is a high-grade intestinal metaplasia that likely represents a precancerous lesion of gastric cancer. High-grade DM is expected to effectively prevent progression to gastric cancer in H. pylori-positive patients.

Development of a strategy to identify and evaluate direct and indirect activators of constitutive androstane receptor in rats.

Constitutive androstane receptor (CAR) is a nuclear receptor that plays a key role in drug metabolism and disposition and in the development of liver tumors in rodents. CAR is activated by ligands and indirect activators, which do not bind to the receptor but activate it through cellular signaling. In this study, we sought to identify direct and indirect activators of rat CAR (rCAR). Assessment of the influence of mutations on the transcriptional activity of rCAR identified a mutant termed rCAR-3A-G354Q that displays low constitutive activity and high ligand responsiveness. Reporter assays using the mutant were performed with compounds that increased the mRNA levels of Cyp2b1, a CAR target gene, in rat primary hepatocytes. Several compounds activated rCAR-3A-G354Q and were implicated as rCAR ligands. Since indirect CAR activators are considered to display little species differences, we then determined CYP2B6 mRNA levels in human hepatocyte-like HepaRG cells after treatment with compounds that increased Cyp2b1 mRNA levels in rat hepatocytes but did not activate rCAR-3A-G354Q. The results demonstrated six compounds as possible rCAR indirect activators. Taken together, the combined measurement of Cyp2b1 mRNA levels in rat primary hepatocytes and rCAR-3A-G354Q activation in reporter assays can be useful for evaluating rCAR activation by chemicals.

Gemcitabine Resistance in Pancreatic Ductal Carcinoma Cell Lines Stems from Reprogramming of Energy Metabolism.

Pancreatic ductal adenocarcinoma (PDAC) is associated with poor prognosis because it is often detected at an advanced stage, and drug resistance interferes with treatment. However, the mechanism underlying drug resistance in PDAC remains unclear. Here, we investigated metabolic changes between a parental PDAC cell line and a gemcitabine (GEM)-resistant PDAC cell line. We established a GEM-resistant cell line, MIA-G, from MIA-PaCa-2 parental (MIA-P) cells using continuous therapeutic-dose GEM treatment. MIA-G cells were also more resistant to 5-fluorouracil in comparison to MIA-P cells. Metabolic flux analysis showed a higher oxygen consumption rate (OCR) in MIA-G cells than in MIA-P cells. Notably, OCR was suppressed by GEM treatment only in MIA-G cells. GEM treatment increased mitochondrial membrane potential and mitochondrial reactive oxygen species (ROS) in MIA-P cells, but not in MIA-G cells. Glutamine uptake and peroxidase levels were elevated in MIA-G cells. The antioxidants N-acetyl-L-cysteine and vitamin C increased the sensitivity to GEM in both cell lines. In MIA-G cells, the expression of the mitochondrial transcription factor A also decreased. Furthermore, rotenone reduced the sensitivity of MIA-P cells to GEM. These findings suggest that the suppression of oxidative phosphorylation contributes to GEM resistance by reducing ROS production. Our study provides a new approach for reducing GEM resistance in PDAC.

Development of an adenovirus-mediated reporter assay system to detect a low concentration of retinoic acid in MCF-7 cells.

Retinoic acid, an active form of vitamin A, plays very important roles in mammalian embryogenesis. The concentration of retinoic acid is extremely low and strictly regulated by enzymes of cytochrome P450 (CYP) family, CYP26s (CYP26A1, CYP26B1 and CYP26C1) in the cells. Therefore, it is thought that changes in CYP26s activities due to exposure to a wide variety of drugs and chemicals exhibit teratogenicity. In this study, to easily detect the changes in retinoic acid level, we constructed an adenovirus-mediated reporter assay system using the promoter region of the CYP26A1 gene and inserting retinoic acid response element (RARE) and retinoid X response element (RXRE) into the downstream of the luciferase gene of reporter plasmid, which highly increased the response to retinoic acid. Reporter activity significantly increased in a concentration-dependent manner with retinoic acid; this increase was also observed at least after treatment with a very low concentration of 1 nM retinoic acid. This increase was suppressed by the accelerated metabolism of retinoic acid due to the overexpression of CYP26A1; however, this suppression was almost completely suspended by treatment with talarozole, a CYP26 inhibitor. In conclusion, the reporter assay system constructed using the induction of CYP26A1 expression is a risk assessment system that responds to extremely low concentrations of retinoic acid and is useful for assessing the excess vitamin A mediated teratogenicity caused by various chemicals at the cellular level.

Oxidized high mobility group B-1 enhances metastability of colorectal cancer via modification of mesenchymal stem/stromal cells.

High mobility group box-1 (HMGB1) is known to be a chemotactic factor for mesenchymal stem/stromal cells (MSCs), but the effect of post-translational modification on its function is not clear. In this study, we hypothesized that differences in the oxidation state of HMGB1 would lead to differences in the function of MSCs in cancer. In human colorectal cancer, MSCs infiltrating into the stroma were correlated with liver metastasis and serum HMGB1. In animal models, oxidized HMGB1 mobilized three-fold fewer MSCs to subcutaneous tumors compared with reduced HMGB1. Reduced HMGB1 inhibited the proliferation of mouse bone marrow MSCs (BM-MSCs) and induced differentiation into osteoblasts and vascular pericytes, whereas oxidized HMGB1 promoted proliferation and increased stemness, and no differentiation was observed. When BM-MSCs pretreated with oxidized HMGB1 were co-cultured with syngeneic cancer cells, cell proliferation and stemness of cancer cells were increased, and tumorigenesis and drug resistance were promoted. In contrast, co-culture with reduced HMGB1-pretreated BM-MSCs did not enhance stemness. In an animal orthotopic transplantation colorectal cancer model, oxidized HMGB1, but not reduced HMGB1, promoted liver metastasis with intratumoral MSC chemotaxis. Therefore, oxidized HMGB1 reprograms MSCs and promotes cancer malignancy. The oxidized HMGB1-MSC axis may be an important target for cancer therapy.

Sunitinib and Pterostilbene Combination Treatment Exerts Antitumor Effects in Gastric Cancer via Suppression of PDZD8.

The use of molecular-targeted drugs in the treatment of gastric cancer is increasing. However, the variety of molecular-targeted drugs in gastric cancer is still limited, and the development of new molecular-targeted therapies is required. The effect of combining sunitinib (SUN) with pterostilbene (PTE) on the human gastric cancer cell lines TMK1 and MKN74 was examined in in vitro and in vivo. Compared with SUN or PTE treatment alone, cotreatment induced pronounced suppression of cell proliferation, with a marked increase in oxidative stress. SUN was associated with a significant retention of mitochondrial Fe2+. SUN-treated cells decreased expression of PDZ domain-containing protein 8 (PDZD8). Knockdown of PDZD8 in both cells induced Fe2+ retention, and siPDZD8+PTE markedly suppressed cell proliferation with suppressed oxidative phosphorylation, as did the combination of SUN+PTE. In a nude mouse tumor model, a pronounced antitumor effect was observed with SUN+PTE treatment compared to SUN alone. PDZD8 may be a newly discovered off-target for SUN, and that the combined use of PTE with SUN significantly promotes antitumor activity in gastric cancer cell lines. The combined use of SUN and PTE might be a new molecular-targeted therapy for gastric cancer.

Suppressive GLI2 fragment enhances liver metastasis in colorectal cancer.

Linoleic acid (LA) has been shown to cause inflammation and promote development of colorectal cancer (CRC). Moreover, many literatures show that LA is associated with cancer metastasis. Metastatic cancer cells have high stemness, suggesting that LA might affect the stemness of cancer cells. In this study, we examined the effect of LA on the hedgehog system, which affects cancer stemness. In CT26 cells, LA treatment induced the expression of sonic hedgehog (Shh); the signal transduction factor, and glioma-associated oncogene homolog (Gli) 2, whereas the expression of SRY-box transcription factor (Sox) 17 was suppressed. Furthermore, LA reduced GLI2 ubiquitination, resulting in an increase in the N-terminal fragment of GLI2, known as suppressive GLI2, produced by cleavage of GLI2. LA-induced cleaved GLI2 was also detected in Colo320 and HT29 human CRC cells. Knocking down Gli2 abrogated the LA-mediated suppression of Sox17 expression. These results suggest that LA promotes tumor cell stemness by increasing of suppressive GLI2 fragments via GLI2 modification. In mouse liver metastasis models, LA enhanced metastasis with production of the suppressive GLI2 fragments in CT26 and HT29 cells, whereas knockdown of GLI2 abrogated LA-induced metastatic activity. In human CRCs, the cases with liver metastasis showed the suppressive GLI2 fragments. This study provides mechanistic insights into LA-induced stemness in colon cancer cells. This finding suggests that dietary intake of LA might increase the stemness of cancer cells and enhance metastatic activity of the cancer.