Preparation and in Vitro Characterization of Fatty-Acid Modified Pirarubicin Nanosuspensions Stabilized by Albumin.

Pirarubicin (THP) shows more rapid intracellular uptake, more effective antitumor activity, and less cardiac toxicity, compared to doxorubicin. However, THP is distributed to both tumor and normal tissues indiscriminately. This study aimed to develop a nanosuspension to deliver THP to tumor tissues more efficiently. Fatty-acid-modified THPs (FA-THPs; octanoic acid, dodecanoic acid, palmitic acid-THPs) were synthesized to increase the hydrophobicity of THP. Nanosuspensions of these FA-THPs were then prepared using an antisolvent precipitation technique. Among the FA-THPs, the most efficiently drug-loaded nanosuspension was obtained from palmitic acid-THP (pal-THP) using an aqueous antisolvent containing bovine serum albumin as a stabilizer. The pal-THP nanoparticles in the nanosuspension were confirmed to be of optimal size (100-125 nm) for delivery to tumor tissues using dynamic light scattering and transmission electron microscopy. The pal-THP nanosuspension showed cytotoxicity in colon 26 cells. The nanosuspension was shown to disintegrate in the presence of surfactants such as lecithin, liberating pal-THP, which was converted to free THP in acidic media. It is therefore proposed that pal-THP nanoparticles that reach tumor cells after intravenous administration would exert antitumor effect by liberating pal-THP (i.e., disintegration of nanoparticles by the interaction with cell membrane), followed by the release of free THP in the acidic milieu of tumor cells. These findings indicate that FA-THP nanosuspensions, particularly pal-THP nanosuspension, hold promise as a candidate for cancer treatment. However, further in vivo studies are necessary.

A case of percutaneous retrieval of a catheter without a free end that was fractured during a totally implantable venous access port removal.

Totally implantable venous access ports (TIVAPs) are widely used for chemotherapy and other purposes in patients with cancer. Their convenience and safety make them ideal for long-term use. However, sometimes there are cases in which TIVAPs remain in the vessel following the completion of long-term chemotherapy and are difficult to remove due to the adhesion of the catheter to the vessel wall. In this study, we encountered a case in which a TIVAP catheter adhering to a blood vessel was fractured during removal and the catheter left in the vessel could not be retrieved by a snare because it had no free end. Finally, the catheter was successfully removed using a peel-away sheath. No complications or residual catheters were associated with the removal procedure.

Methylmercury directly modifies the 105th cysteine residue in oncostatin M to promote binding to tumor necrosis factor receptor 3 and inhibit cell growth.

We previously found that methylmercury induces expression of oncostatin M (OSM), which is released extracellularly and binds to tumor necrosis factor receptor 3 (TNFR3), possibly enhancing its own toxicity. However, the mechanism by which methylmercury causes OSM to bind to TNFR3 rather than to its known receptors, OSM receptor and LIFR, is unknown. In this study, we aimed to elucidate the effect of methylmercury modification of cysteine residues in OSM on binding to TNFR3. Immunostaining of TNFR3-V5-expressing cells suggested that methylmercury promoted binding of OSM to TNFR3 on the cell membrane. In an in vitro binding assay, OSM directly bound to the extracellular domain of TNFR3, and this binding was promoted by methylmercury. Additionally, the formation of a disulfide bond in the OSM molecule was essential for the binding of both proteins, and LC/MS analysis revealed that methylmercury directly modified the 105th cysteine residue (Cys105) in OSM. Next, mutant OSM, in which Cys105 was replaced by serine or methionine, increased the binding to TNFR3, and a similar effect was observed in immunoprecipitation using cultured cells. Furthermore, cell proliferation was inhibited by treatment with Cys105 mutant OSMs compared with wildtype OSM, and this effect was cancelled by TNFR3 knockdown. In conclusion, we revealed a novel mechanism of methylmercury toxicity, in which methylmercury directly modifies Cys105 in OSM, thereby inhibiting cell proliferation via promoting binding to TNFR3. This indicates a chemical disruption in the interaction between the ligand and the receptor is a part of methylmercury toxicity.

A Promising Needle-Free Pyro-Drive Jet Injector for Augmentation of Immunity by Intradermal Injection as a Physical Adjuvant.

Current worldwide mRNA vaccination against SARS-CoV-2 by intramuscular injection using a needled syringe has greatly protected numerous people from COVID-19. An intramuscular injection is generally well tolerated, safer and easier to perform on a large scale, whereas the skin has the benefit of the presence of numerous immune cells, such as professional antigen-presenting dendritic cells. Therefore, intradermal injection is considered superior to intramuscular injection for the induction of protective immunity, but more proficiency is required for the injection. To improve these issues, several different types of more versatile jet injectors have been developed to deliver DNAs, proteins or drugs by high jet velocity through the skin without a needle. Among them, a new needle-free pyro-drive jet injector has a unique characteristic that utilizes gunpower as a mechanical driving force, in particular, bi-phasic pyrotechnics to provoke high jet velocity and consequently the wide dispersion of the injected DNA solution in the skin. A significant amount of evidence has revealed that it is highly effective as a vaccinating tool to induce potent protective cellular and humoral immunity against cancers and infectious diseases. This is presumably explained by the fact that shear stress generated by the high jet velocity facilitates the uptake of DNA in the cells and, consequently, its protein expression. The shear stress also possibly elicits danger signals which, together with the plasmid DNA, subsequently induces the activation of innate immunity including dendritic cell maturation, leading to the establishment of adaptive immunity. This review summarizes the recent advances in needle-free jet injectors to augment the cellular and humoral immunity by intradermal injection and the possible mechanism of action.

Investigation of the body-centred tetragonal structure of Fe-Co-V-N Bulk foils using the rolling and ammonia-gas-nitriding method.

Improving the properties of permanent magnets is essential for the advancement of electric motors in reducing energy consumption and carbon emissions. This study investigated the effect of V and N addition to FeCo foils on the stability of tetragonally distorted FeCo-based bulk magnets. The incorporation of these two elements stabilised the body-centred tetragonal structure in thin-film and bulk systems. Fe-Co-V ingots were rolled and nitrided by ammonia gas at 650 °C for 5 h. A body-centred tetragonal lattice with an axial ratio of c/a ≈ 1.1 was observed by transmission electron microscopy, and the collected data suggested the induction of a large uniaxial magnetic anisotropy. This study is expected to improve our understanding of rare-earth-free magnets.

Intracellular glutathione levels affect the outcomes of verteporfin-mediated photodynamic therapy in esophageal cancer cells.

Photodynamic therapy (PDT) induces cancer cell death by generating reactive oxygen species (ROS). In this process, photosensitizers accumulate in cancer cells irradiated by laser light of a specific wavelength, leading to ROS generation. Verteporfin (VP), a second-generation photosensitizer, is used in PDT for age-related macular degeneration. However, the antitumor effects of VP-PDT remain poorly defined. This study investigated the antitumor effects of VP-PDT on esophageal cancer (EC) cell lines in vitro. Two types of EC cell lines, the KYSE30 cell line, derived from highly differentiated esophageal carcinoma, and the KYSE170 cell line, derived from moderately differentiated carcinoma, were used in this study. VP-PDT exerted effective anticancer effects in both cell lines. Our results revealed that the low-density lipoprotein receptor, albumin receptor, and heme carrier protein-1 in VP uptake were not involved in VP uptake. However, cells rich in intracellular glutathione were resistant to VP-PDT. Our study outcomes suggest that lowering intracellular glutathione via a glutathione synthesis inhibitor or sulfasalazine can increase the effectiveness of VP-PDT-mediated anticancer effects.

Cerebral Tufted Angioma with Gradually Developing Peritumoral Edema: A Case Report.

Tufted angioma is a benign vascular tumor in which immature endothelial and pericyte cells and lymphatic vascular endothelium grow. It manifests as a flat, painful erythema that gradually expands mainly on the trunk and extremities. Although tufted angiomas can also occur in other areas of the body and may be more locally invasive, they rarely occur intracranially. A 63-year-old man underwent magnetic resonance imaging (MRI) for a brain check-up 8 years before his visit to our institute, which detected a mass lesion with surrounding cerebral edema in the left frontal lobe. The patient was followed up with annual MRI analysis, which indicated slow tumor growth and gradual development of peritumoral edema. The tumor was treated by gross-total resection. Histological analysis showed a slightly dilated microvascular core surrounded by many capillary aggregates in the brain parenchyma. Immunohistochemical findings indicated that the vascular endothelial cells were positive for CD34 and Brahma-related gene-1 and were surrounded by smooth muscle actin-positive pericytes. These findings were consistent with tufted angioma. Intracranial tufted angioma is uncommon, but it should be considered in the differential diagnosis for intracranial tumorous lesions. Long-term follow-up is necessary to unravel the natural history of the disease.

[A case of foveolar-type gastric adenocarcinoma with a raspberry-like appearance followed up by endoscopy].

A 47-year-old man was referred to our hospital for detailed examination of a gastric polypoid lesion. Esophagogastroduodenoscopy revealed a raspberry-like polyp at the gastric body. Pathological examination of the biopsy specimen revealed this polypoid lesion to be a gastric adenocarcinoma. Endoscopic submucosal dissection was performed, and histopathological examination revealed that lesion to be a well-differentiated adenocarcinoma. Immunohistochemical staining showed that the neoplasm was positive for MUC5AC and negative for MUC6, CD10, and pepsinogen I, indicating that this lesion was a foveolar-type gastric adenocarcinoma. From about 10 years now, this patient has been undergoing esophagogastroduodenoscopy almost every year. This lesion was absent until six years ago. Five years ago, a small polypoid lesion appeared at the gastric body, and this lesion gradually enlarged. The present case showed the growing process of the foveolar-type gastric adenocarcinoma with a raspberry-like appearance.

Effect of Dupilumab on Depression in Asthma with Eosinophilic Chronic Rhinosinusitis in the Japanese Population.

INTRODUCTION: Psychological disorders, such as depression, are markedly prevalent in patients with airway diseases. In this study, we assessed the effect of treatment with dupilumab, an IL-4 receptor α chain antibody, on depressive symptoms in a cohort of patients with asthma with eosinophilic chronic rhinosinusitis (ECRS). METHODS: The study participants, diagnosed with asthma and ECRS, were assessed for symptoms and quality of life (QOL) scores for asthma and ECRS and medications. The Patient Health Questionnaire-9 (PHQ-9) scores were used to evaluate the depressive state. The depressive symptoms were compared with asthma and ECRS symptoms both at the time of initiation and after 4 months of dupilumab treatment. RESULTS: Ultimately, 31 patients were included in the study. Most patients demonstrated a depressive state that was correlated with the nasal symptom score. In the evaluation 4 months after dupilumab treatment, the PHQ-9 score was significantly reduced, and the decrease was remarkable in patients whose nasal symptom score was reduced by 50% or more. Additionally, the PHQ-9 scores in patients with improved nasal and asthma symptoms were significantly reduced. DISCUSSION/CONCLUSION: Dupilumab may improve QOL in patients with bronchial asthma with ECRS by reducing depressive symptoms through the improvement of clinical symptoms.

Photosensitizer verteporfin inhibits the growth of YAP- and TAZ-dominant gastric cancer cells by suppressing the anti-apoptotic protein Survivin in a light-independent manner.

Yes-associated protein (YAP) positivity indicates a poor prognosis in gastric cancer. Transcriptional co-activator with a PDZ-binding domain (TAZ), a YAP paralog, is highly expressed in gastric signet ring cell carcinoma. Verteporfin (VP), a clinical photosensitizer, was recently shown to inhibit YAP/TAZ. In the present study, the therapeutic potential of VP treatment was explored using two gastric cancer cell lines: MKN-45 (TAZ-dominant) and MKN-74 (YAP-dominant). Cell proliferation was evaluated by MTS assay. Vascular mimicry was evaluated by the tube formation assay. Gene and protein expression levels of YAP/TAZ downstream effectors [such as Survivin, Cysteine-rich angiogenic inducer 61 (CYR61), and connective tissue growth factor (CTGF)] were measured. YAP or TAZ localization was evaluated by immunofluorescence. Cell death was assessed by immunofluorescent staining of Annexin V. YAP and TAZ expression were knocked down by small interfering RNA. The current results demonstrate that MKN-45, a poorly differentiated TAZ-dominant gastric cancer cell line, was more sensitive to VP than MKN-74, a moderately differentiated YAP-dominant gastric cancer cell line. VP changed the localization of YAP/TAZ, promoted its degradation and significantly decreased the protein level of Survivin in both cell lines. Cell death was induced by VP treatment in a dose-dependent manner. Vascular mimicry was inhibited in both cell lines. Proliferation in both cell lines decreased in response to YAP/TAZ knockdown. The present study indicated that VP has potential as a therapeutic agent in YAP- and TAZ-dominant gastric cancers due to its ability to suppress the anti-apoptotic protein Survivin via inhibition of YAP and TAZ.

Factors affecting the recovery of hepatic reserve after sustained virologic response by direct-acting antiviral agents in chronic hepatitis C virus-infected patients.

BACKGROUND AND AIM: Since the advent of direct-acting antiviral (DAA) therapy, the total eradication of hepatitis C virus has been achievable with the recovery of hepatic reserve after achievement of sustained virologic response (SVR). Hence, here, we examined the factors affecting the recovery of hepatic reserve. METHODS: We followed up 403 patients (male: 164, female: 239; genotype 1: 299, genotype 2: 104; median age: 69 years) for at least 3 years after they achieved SVR to DAA therapy. Of these patients, 75 (18.6%) had a history of hepatocellular carcinoma (HCC). Biochemical tests were periodically performed, and the hepatic reserve was evaluated based on the albumin-bilirubin grade. We examined background factors such as age, biochemical test results, HCC occurrence and portosystemic shunt by computed tomography. RESULTS: At the start of treatment, the albumin-bilirubin grades were grades 1, 2, and 3 in 241, 157, and 5 patients, respectively, and 3 years later, 117 of 162 (72%) patients with grade 2 or 3 improved to grade 1. Multivariate analysis identified the HCC occurrence after achievement of SVR (hazard ratio [HR]: 3.08, P < 0.0138), male sex (HR: 3.45, P = 0.0143), hemoglobin level of <11.5 g/dL (HR: 4.19, P = 0.0157), the presence of a portosystemic shunt (HR: 3.07, P = 0.0349), and alanine aminotransferase levels <45 U/L (HR: 2.67, P = 0.0425) as factors inhibiting improvement to grade 1. However, old age was not an inhibitory factor. CONCLUSION: Our results demonstrate that hepatic reserve could be improved even in elderly patients over a long course of time.

Verteporfin-photodynamic therapy is effective on gastric cancer cells.

Photodynamic therapy (PDT) induces photochemical reactions, resulting in the destruction of tumor cells via singlet (S1) oxygen production. This cellular destruction occurs specifically in tumor cells, following selective accumulation of a photosensitizer and its excitation by a specific wavelength. Verteporfin (VP) is a second-generation photosensitizer that is currently being used worldwide in PDT to treat age-related macular degeneration. In addition, clinical trials with VP-PDT demonstrated anti-tumor efficacy and overall safety when used to treat locally advanced pancreatic cancer. In the present study, we examined the anti-tumor effect of VP-PDT on gastric cancer (GC) cell lines in vitro to conduct an initial assessment of its potential clinical applicability to this specific type of cancer. We evaluated the viability of MKN45 and MKN74 cancer cell lines after VP-PDT exposure and calculated the half maximal effective concentration (EC50) values for VP. Apoptosis in VP-PDT-exposed GC cells was observed. Furthermore, the EC50 values for a 30-min treatment with VP (2.5 J/cm2 of 660 nm LED light) were 0.61 and 1.21 µM for MKN45 and MKN74, respectively. When VP treatment times were increased, the EC50 values decreased. In conclusion, VP-PDT may be developed as an effective treatment for GC.

Next-generation laser-based photodynamic endoscopic diagnosis using 5-aminolevulinic acid for early gastric adenocarcinoma and gastric adenoma.

BACKGROUND: Photodynamic diagnosis (PDD) is an optical imaging technology based on the fundamental biological features of porphyrin metabolized in cancer cells. We reported the usefulness of laser-based photodynamic endoscopic diagnosis (LPDED) with 5-aminolevulinic acid (5-ALA) for early gastric cancers. However, the first-generation prototype endoscope system had the flaw that the images captured were rather dark. To overcome this, we constructed a next-generation endoscope system for LPDED. METHODS: We evaluated the usefulness of the next-generation prototype endoscope system, called Sie-P2, for brighter LPDED to detect early gastric cancer (EGC) and gastric adenoma. The 14 patients diagnosed with EGC and/or gastric adenoma who underwent endoscopic submucosal dissection (ESD) at our hospital between April 2018 and March 2019 were enrolled consecutively in this study. Patients were administered 5-ALA orally and LPDED was performed 3 h later. The primary endpoint was the presence of fluorescence in tumors when we performed LPDED. The secondary endpoint was to assess the adverse events related to each LPDED procedure. RESULTS: One patient was excluded because of a contraindication, while the remaining 13 patients (median 72 years, range 56-77; one female) with 16 lesions were assessed. There were 10 elevated lesions and 6 flat/depressed lesions; there were 10 EGCs and 6 adenomas. LPDED-fluorescence was detected in all 16 lesions (sensitivity 100%, 95% confidence interval 79-100%). Two cases showed temporary, though not substantial, elevation in blood liver function tests. CONCLUSION: All lesions examined were LPDED-positive, indicating that the Sie-P2 system could be useful.

Cysteinyl Leukotriene Synthesis via Phospholipase A2 Group IV Mediates Exercise-induced Bronchoconstriction and Airway Remodeling.

It is well known that the prevalence of asthma is higher in athletes, including Olympic athletes, than in the general population. In this study, we analyzed the mechanism of exercise-induced bronchoconstriction by using animal models of athlete asthma. Mice were made to exercise on a treadmill for a total duration of 1 week, 3 weeks, or 5 weeks. We analyzed airway responsiveness, BAL fluid, lung homogenates, and tissue histology for each period. In mice that were treated (i.e., the treatment model), treatments were administered from the fourth to the fifth week. We also collected induced sputum from human athletes with asthma and analyzed the supernatants. Airway responsiveness to methacholine was enhanced with repeated exercise stimulation, although the cell composition in BAL fluid did not change. Exercise induced hypertrophy of airway smooth muscle and subepithelial collagen deposition. Cysteinyl-leukotriene (Cys-LT) levels were significantly increased with exercise duration. Montelukast treatment significantly reduced airway hyperresponsiveness (AHR) and airway remodeling. Expression of PLA2G4 (phospholipase A2 group IV) and leukotriene C4 synthase in the airway epithelium was upregulated in the exercise model, and inhibition of PLA2 ameliorated AHR and airway remodeling, with associated lower levels of Cys-LTs. The levels of Cys-LTs in sputum from athletes did not differ between those with and without sputum eosinophilia. These data suggest that AHR and airway remodeling were caused by repeated and strenuous exercise. Cys-LTs from the airway epithelium, but not inflammatory cells, may play an important role in this mouse model.

Association of upper and lower airway eosinophilic inflammation with response to omalizumab in patients with severe asthma.

Background: The anti-immunoglobulin E monoclonal antibody, omalizumab, is used to treat severe asthma and has the potential to ameliorate airway inflammation. However, the effect of omalizumab in ameliorating upper airway inflammation has not been fully elucidated. Objective: We investigated the association of upper and lower airway inflammation with the response to omalizumab treatment. Methods: We used the Global Evaluation of Treatment Effectiveness to assess the efficacy of omalizumab in treating 16 patients with severe asthma. We also investigated the symptom score, short-acting ß-agonist inhaler use, pulmonary function, biomarkers, computed tomography scans, and nasal mucosa pathology at omalizumab initiation and after four months of treatment. Results: When the fraction of exhaled nitric oxide (FeNO) and the percentage of sputum eosinophil were used as indicators of lower airway inflammation, positive correlations were found between CD20 B-cell, mast cell, and eosinophil counts in the nasal mucosa. Improved asthma symptoms were observed in 12 of the 16 severe asthma cases. The FeNO and eosinophil levels in the nasal tissue, prior to the administration of omalizumab were predictors of the response to asthma treatment. Conclusions: These findings suggest heterogeneity among people with severe asthma. In addition, the phenotype associated with response to omalizumab, leading to improvement in asthma symptoms, comprises upper airway eosinophilia and high FeNO levels.

A study of factors related to asthma exacerbation using a questionnaire survey in Niigata Prefecture, Japan.

BACKGROUND: As indices of asthma control, exacerbations are equally important with symptoms and respiratory function. Thus, it is critical to recognize the risk factors of exacerbation. OBJECTIVE: We conducted a questionnaire survey of asthma patients in Niigata Prefecture to clarify the factors involved in asthma exacerbation. METHODS: The questionnaire survey was carried out in patients and their physicians from September to October 2014. In 2015, the same sample population also received a questionnaire about current asthma control and exacerbation. RESULTS: One hundred patients experienced asthma exacerbation during the 1-year period. There were significant differences in age, sex, history of hospitalization due to asthma, smoking history, Asthma Control Test, treatment step, and transient steroid treatment history in the previous year between the exacerbation group and non-exacerbation group. On multivariate analysis, there was a significant difference in history of transient steroid therapy, history of hospitalization associated with asthma attacks, and nonsmoking history. Cluster analysis of cases with exacerbation was classified into three clusters. Cluster 1 comprised slightly older cases with smoking history, Cluster 2 had more females, non-smoking and nonatopic cases with uncontrolled symptoms, and Cluster 3 had more females, non-smoking and mild atopic cases. CONCLUSIONS: Our findings suggest that patients with asthma exacerbation in the previous year and nonsmoking females are important targets for the study of asthma exacerbation. The adequate treatment of women patients might be important for the prevention of asthma exacerbation.

Characterization of low adherence population in asthma patients from Japan using Adherence Starts with Knowledge-12.

BACKGROUND: Adherence Starts with Knowledge-12 (ASK-12) is a useful indicator of drug adherence. In this study, we analyzed patient background including social and psychological factors in a low-adherence group of patients with asthma defined using ASK-12. METHODS: From a questionnaire survey for patients with asthma from the Niigata Prefecture, Japan, conducted in the fall of 2016, we enrolled patients who answered all ASK-12 items and underwent a measured respiratory function test within 1 year. The low-adherence group (ASK-12 ≥ 28) was compared with the control group (ASK-12 < 28), and we conducted a cluster analysis of the low-adherence group. RESULTS: There were 170 patients in the low-adherence group and 402 patients in the control group. There was a significant difference between age, gender, working status, smoking history, the percentage of forced expiratory volume in one second (%FEV1), asthma control test (ACT), and Patient Health Questionnaire-9 (PHQ-9) score between the two groups. Logistic analysis revealed that working status (working), % FEV1 (<90%), and PHQ-9 score (>5) were independent factors for the low-adherence group. The cluster analysis identified three clusters in the low-adherence group. Among these, one cluster was characterized by elderly males with chronic obstructive pulmonary disease and another by middle-aged nonsmoking females with a depression tendency, had problems with asthma control. CONCLUSIONS: Several factors were considered to be attributed to low drug-adherence. There were several phenotypes in the low-adherence population correlated with incomplete asthma control. Intervention with drug adherence should be a future goal for asthma treatment.

The Nuclear Protein HOXB13 Enhances Methylmercury Toxicity by Inducing Oncostatin M and Promoting Its Binding to TNFR3 in Cultured Cells.

Homeobox protein B13 (HOXB13), a transcription factor, is related to methylmercury toxicity; however, the downstream factors involved in enhancing methylmercury toxicity remain unknown. We performed microarray analysis to search for downstream factors whose expression is induced by methylmercury via HOXB13 in human embryonic kidney cells (HEK293), which are useful model cells for analyzing molecular mechanisms. Methylmercury induced the expression of oncostatin M (OSM), a cytokine of the interleukin-6 family, and this was markedly suppressed by HOXB13 knockdown. OSM knockdown also conferred resistance to methylmercury in HEK293 cells, and no added methylmercury resistance was observed when both HOXB13 and OSM were knocked down. Binding of HOXB13 to the OSM gene promoter was increased by methylmercury, indicating the involvement of HOXB13 in the enhancement of its toxicity. Because addition of recombinant OSM to the medium enhanced methylmercury toxicity in OSM-knockdown cells, extracellularly released OSM was believed to enhance methylmercury toxicity via membrane receptors. We discovered tumor necrosis factor receptor (TNF) receptor 3 (TNFR3) to be a potential candidate involved in the enhancement of methylmercury toxicity by OSM. This toxicity mechanism was also confirmed in mouse neuronal stem cells. We report, for the first time, that HOXB13 is involved in enhancement of methylmercury toxicity via OSM-expression induction and that the synthesized OSM causes cell death by binding to TNFR3 extracellularly.

Low-density lipoprotein receptor expression is involved in the beneficial effect of photodynamic therapy using talaporfin sodium on gastric cancer cells.

Photodynamic therapy (PDT) is a therapeutic method used to destroy tumor tissue via reactive oxygen. Notably, reactive oxygen is induced by a combination of photosensitizers, including talaporfin sodium (TS) and laser light. Gastric cancer cell lines, MKN45 and MKN74, were used to evaluate the effect of TS-PDT in vitro. The antitumor effect of TS-PDT, which was evaluated via cellular viability assay, on MKN74 was weaker than that on MKN45 cells, suggesting that MKN74 cell could be resistant to TS-PDT. However, using a higher TS concentration or setting a longer treatment time (24 h) resulted in effective TS-PDT treatment on MKN74 cells. In addition, when irradiation power of LED was raised up to 5.06 J/cm2, TS-PDT was able to induce an antitumor effect on MKN74 cells. This suggested that the difference in TS-PDT efficacy between MKN45 and MKN74 cells is based on the difference in cellular uptake of TS. As expected, uptake of TS by MKN74 cells was lower than that by MKN45 cells. The expression levels of low-density lipoprotein (LDL) receptor in MKN74 cells were lower than those in MKN45 cells. With GW3965 treatment, an agonist/activator of Liver X Receptor, LDL receptor expression was reduced, weakening the TS-PDT effect. Furthermore, as a hydroxymethylglutaryl-Coenzyme A reductase inhibitor, treatment using simvastatin increased LDL receptor expression, leading to enhancement of the TS-PDT effect on MKN74 cells. In conclusion, the difference in LDL receptor expression between the two gastric cell lines could influence TS-PDT efficacy; simvastatin may enhance the antitumor effect of TS-PDT through upregulating the LDL receptor even on PDT-resistant gastric cancer cells.