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Although cancer immunotherapy using immune checkpoint inhibitors (ICIs) has been recognized as one of the major treatment modalities for malignant diseases, the clinical outcome is not uniform in all cancer patients. Myeloid-derived suppressor cells (MDSCs) represent a heterogeneous population of immature myeloid cells that possess various strong immunosuppressive activities involving multiple immunocompetent cells that are significantly accumulated in patients who did not respond well to cancer immunotherapies. We reviewed the perspective of MDSCs with emerging evidence in this review. Many studies on MDSCs were performed in malignant diseases. Substantial studies on the participation of MDSCs on non-malignant diseases such as chronic infection and autoimmune diseases, and physiological roles in obesity, aging, pregnancy and neonates have yet to be reported. With the growing understanding of the roles of MDSCs, variable therapeutic strategies and agents targeting MDSCs are being investigated, some of which have been used in clinical trials. More studies are required in order to develop more effective strategies against MDSCs.

The prognostic significance of the mean corpuscular volume (MCV) and red cell distribution width (RDW) in patients with malignancy have not been intensely investigated and are largely overlooked. We, therefore, investigated the clinical significance of MCV and RDW in non-metastatic obstructive colorectal cancer (OCRC) patients with a self-expandable metallic stent inserted as a bridge to curative surgery.Eighty-five pathological stage II and III OCRC patients were retrospectively evaluated. The associations of the preoperative MCV and RDW values with short- and long-term outcomes were examined.There were 50 males and 35 females, and the median age was 71 years old. The median interval between stenting and surgery was 17 days, and the median postoperative hospital stay was 16 days. Fifty-six patients were in the MCV ≥ 87 group, and 47 were in the RDW ≥ 13.8 group. Multivariate analyses revealed the MCV ≥ 87 status to be independently associated with a poor relapse-free survival (hazard ratio [HR] = 4.70, 95% confidence interval [CI] 1.52-14.58, P = 0.007). The RDW ≥ 13.8% was an independent predictor of postoperative infectious complications (HR = 7.28, 95% CI 1.24-42.70, P = 0.028).The MCV and RDW are simple but strong predictors of postoperative outcomes in OCRC patients.

Intestinal decompression using self-expandable metallic colonic stents (SEMSs) as a bridge to surgery is now considered an attractive alternative to emergency surgery. However, data regarding the optimal timing of surgery after stenting are limited. We investigated the impact of the interval between stenting and surgery on short- and long-term outcomes in 92 obstructive colorectal cancer (OCRC) patients who had a SEMS inserted and subsequently received curative surgery. The median age of the patients was 70.5 years, and the median interval between SEMS insertion and the surgery was 17 (range 5–47) days. There were 35 postoperative complications, including seven major postoperative complications. An interval of more than 16 days was an independent predictor of a poor relapse-free survival (hazard ratio [HR] = 3.12, 95% confidence interval [CI] 1.24–7.81, p = 0.015). An interval of more than 35 days was independently associated with major postoperative complications (HR = 16.6, 95% CI 2.21–125, p = 0.006). A longer interval between stenting and surgery significantly compromised the short- and long-term outcomes. Surgery within 16 days after stenting might help maximize the benefit of SEMS without interfering with short- and long-term outcomes.

Objectives: It has been increasingly recognized that the progression of cancer is dependent not only on the tumor characteristics but also on the nutritious and inflammatory condition of the host. We investigated the relationship between the globulin-to-albumin ratio (GAR) and long-term outcomes in obstructive colorectal cancer (OCRC) patients who were inserted self-expandable metallic stent as a bridge to curative surgery. Methods: A total of 75 pathological stage II and III OCRC patients between 2013 and 2020 were retrospectively evaluated. The associations of the preoperative GAR with clinicopathological factors and patient survival were examined. Results: Receiver operating characteristic curve analysis demonstrated that the optimal cutoff value was 0.88. The GAR ≥ 0.88 status was significantly associated with the absence of lymph node metastasis (P = 0.011), longer postoperative hospital stay (17 days vs 15 days, P = 0.042), and not receiving adjuvant chemotherapy (P = 0.011). Relapse-free survival and cancer-specific survival were significantly shorter in the GAR ≥ 0.88 group (P = 0.007 and P = 0.023, respectively). Multivariate analyses revealed that the GAR ≥ 0.88 was independently associated with relapse-free survival [hazard ratio (HR) = 4.17, 95% confidence interval (CI) 1.32-13.14, P = 0.015)]. Moreover, CA19-9 ≥ 37 (HR = 6.56, 95% CI 2.12-20.27, p = 0.001) and not receiving adjuvant chemotherapy (HR = 4.41, 95% CI 1.28-15.26, p = 0.019) were independent poor prognostic factors for relapse-free survival. Conclusions: The results demonstrated that the GAR was a significant prognostic factor for OCRC patients.

Under aquaculture conditions, Japanese eels (

It was reported that nicotinic acetylcholine receptor (nAChR)-mediated signaling pathways affect the proliferation and differentiation of pluripotent stem cells. However, detail expression profiles of nAChR genes were unrevealed in these cells. In this study, we comprehensively investigated the gene expression of a subunit of nAChRs (Chrna) during differentiation and induction of pluripotent stem cells. Mouse embryonic stem (ES) cells expressed multiple Chrna genes (Chrna3-5, 7 and 9) in undifferentiated status. Among them, Chrna9 was markedly down-regulated upon the differentiation into mesenchymal cell lineage. In mouse tissues and cells, Chrna9 was mainly expressed in testes, ES cells and embryonal F9 teratocarcinoma stem cells. Expression of Chrna9 gene was acutely reduced during differentiation of ES and F9 cells within 24 h. In contrast, Chrna9 expression was increased in induced pluripotent stem cells established from mouse embryonic fibroblast. It was shown by the reporter assays that T element-like sequence in the promoter region of Chrna9 gene is important for its activities in ES cells. Chrna9 was markedly reduced by siRNA-mediated knockdown of Tbx3, a pluripotency-related transcription factor of the T-box gene family. These results indicate that Chrna9 is a nAChR gene that are transcriptionally regulated by Tbx3 in undifferentiated pluripotent cells.

11-ketotestosterone (11-KT) is one of the active androgens, which belongs to the novel 11-oxygenated class of androgens. Although 11-KT has been regarded as a teleost-specific androgen, it was recently demonstrated that 11-KT is a major human androgen. However, the details of its functions and dynamics remain unknown. Deficiency of proper animal model is one of the reasons for this. Although rodent models have contributed to reveal synthesis and functions of steroid hormones, only small amounts of 11-KT are synthesized in mice and rats (Yazawa et al. Endocrinology, 2008). In mammal, 11-KT is abundant in limited animal species, such as non-human primates, pig and guinea pig. This suggest that these animal species are valuable models for determining the functions of 11-KT in mammals. In the present study, we evaluated the production and potential functions of 11-KT in pig. In previous studies, we studied human and murine steroidogenesis using steroidogenic cells-derived from mesenchymal stem cells (MSCs, Yazawa et al. Endocrinology 2006, 2009; Mol Endo, 2010; Endocrine J 2016). Therefore, we first induced steroidogenic cells from porcine subcutaneous preadipocytes (PSPA cells), which originate from MSCs. With the aid of cAMP, adenovirus-mediated introduction of SF-1/Ad4BP induced the differentiation of PSPA cells into 11-KT-producing cells. Using PSPA cell-derived steroidogenic cells and our previously established method (Yazawa et al. JSBMB, 2020), we found that porcine AKR1C1 can convert androstenedione into testosterone (T) and is expressed in adrenal, testis and ovary. In addition, we showed that HSD11B2, one of the essential genes to produce 11-KT from T was expressed in testicular Leydig cells and the adrenal cortex. 11-KT was present in the plasma of both immature male and female pigs, with slightly higher levels in males than in females. T levels were much higher in male pigs. It is noteworthy that 11-KT levels were >10-fold higher than T levels in female pigs. However, castration altered the plasma profiles of 11-KT and T in male pigs to the female-like profiles. 11-KT induced endothelial nitric oxide synthase (eNOS) in porcine vascular endothelial cells. These results indicate that 11-KT is produced in porcine adrenal glands and testes. It can potentially be involved in the regulation of cardiovascular functions through eNOS expression. In addition, these findings indicate that pigs (especially female) represent an ideal model for analyzing the functions of 11-KT in mammal. Presentation: No date and time listed

The Controlling Nutritional Status (CONUT) Score, originally developed as a nutritional screening tool, is a cumulative score calculated from the serum albumin level, total cholesterol level, and total lymphocyte count. Previous studies have demonstrated that the score has significant prognostic value in various malignancies. We investigated the relationship between the CONUT score and long-term survival in obstructive colorectal cancer (OCRC) patients who underwent self-expandable metallic colonic stent placement and subsequently received curative surgery. We retrospectively analyzed 57 pathological stage II and III OCRC patients between 2013 and 2019. The associations between the preoperative CONUT score and clinicopathological factors and patient survival were evaluated. A receiver operating characteristic curve analysis revealed that the optimal cut-off value for the CONUT score was 7. A CONUT score of ≥ 7 was significantly associated with elevated CA19-9 level (p = 0.03). Multivariate analyses revealed that a CONUT score of ≥ 7 was independently associated with cancer-specific survival (hazard ratio [HR] = 10.2, 95% confidence interval [CI] 1.2–85.9, p = 0.03) and disease-free survival (HR = 7.1, 95% CI 2.3–21.7, p = 0.0006). The results demonstrated that the CONUT score was a potent prognostic indicator. Evaluating the CONUT score might result in more precise patient assessment and tailored treatment.

Medaka (Oryzias latipes) is a teleost fish with an XX/XY sex determination system, similar to that of mammals. However, under high temperature conditions, XX medaka is masculinised by elevation of cortisol, the major teleost glucocorticoid. In this study, to identify novel factors in the gonads acting downstream from cortisol during sexual differentiation, we performed RNA sequencing (RNA-seq) analysis using the gonadal regions of larvae reared at normal temperature with and without cortisol, and at high temperature. The RNA-seq and real-time PCR analyses showed that expression of some peroxisome proliferator-activated receptor α (PPARα) signalling-targeted genes was increased by cortisol. PPARα agonist treatment induced masculinisation of XX medaka in some cases, and co-treatment of the agonist with cortisol further induced masculinisation, whereas treatment of pparaa knockout medaka with cortisol or the agonist did not induce masculinisation. This study provides the first evidence that PPARα is involved in environmental sex determination in vertebrates.

Background Oxaliplatin, one of the key cytotoxic drugs for colorectal cancer, frequently causes peripheral neuropathy which leads to dose modification and decreased patients’ quality of life. However, prophylactic or therapeutic measures have not yet been established. Orally administered amino acids, cystine and theanine, promoted the synthesis of glutathione which was one of the potential candidates for preventing the neuropathy. The aim of this study was to determine whether daily oral administration of cystine and theanine attenuated oxaliplatin-induced peripheral neuropathy (OXLIPN). Methods Twenty-eight colorectal cancer patients who received infusional 5-fluorouracil, leucovorin, and oxaliplatin (mFOLFOX6) therapy were randomly and evenly assigned to the cystine and theanine group and the control group. OXLIPN was assessed up to the sixth course using original 7-item questionnaire as well as Common Terminology Criteria for Adverse Events (CTCAE) grading scale. Results Neuropathy scores according to our original questionnaire were significantly smaller in the cystine and theanine group at the fourth (p = 0.026), fifth (p = 0.029), and sixth course (p = 0.038). Furthermore, significant differences were also observed in CTCAE neuropathy grades at the fourth (p = 0.037) and the sixth course (p = 0.017). There was one patient in each group who required dose reduction due to OXLIPN. Except for neurotoxicity, no significant differences were noted in the incidence of adverse events, and the total amount of administered oxaliplatin. Conclusion The results demonstrated the daily oral administration of cystine and theanine attenuated OXLIPN.

Inflammation-based markers predict long-term outcomes of various malignancies. We investigated the relationship between these markers and the long-term survival in obstructive colorectal cancer (OCRC) patients with self-expandable metallic colonic stents (SEMSs) who subsequently received curative surgery. We retrospectively analyzed 72 consecutive pathological stage II and III OCRC patients between 2013 and 2019. The prognostic significance of the prognostic nutritional index (PNI), neutrophil–lymphocyte ratio (NLR), lymphocyte–monocyte ratio (LMR), and platelet–lymphocyte ratio (PLR) was evaluated. The overall survival (OS), cancer-specific survival, and disease-free survival (DFS) were significantly shorter in the PNI

Inflammatory bowel disease (IBD), which includes Crohn’s disease and ulcerative colitis, is an intestinal disorder that causes prolonged inflammation of the gastrointestinal tract. Currently, the etiology of IBD is not fully understood and treatments are insufficient to completely cure the disease. In addition to absorbing essential nutrients, intestinal epithelial cells prevent the entry of foreign antigens (micro-organisms and undigested food) through mucus secretion and epithelial barrier formation. Disruption of the intestinal epithelial homeostasis exacerbates inflammation. Thus, the maintenance and reinforcement of epithelial function may have therapeutic benefits in the treatment of IBD. Muscarinic acetylcholine receptors (mAChRs) are G protein-coupled receptors for acetylcholine that are expressed in intestinal epithelial cells. Recent studies have revealed the role of mAChRs in the maintenance of intestinal epithelial homeostasis. The importance of non-neuronal acetylcholine in mAChR activation in epithelial cells has also been recognized. This review aimed to summarize recent advances in research on mAChRs for intestinal epithelial homeostasis and the involvement of non-neuronal acetylcholine systems, and highlight their potential as targets for IBD therapy.

To study the toxicity of 3-hydroxybenzo[c]phenanthrene (3-OHBcP), a metabolite of benzo[c]phenanthrene (BcP), first we compared it with its parent compound, BcP, using an in ovo-nanoinjection method in Japanese medaka. Second, we examined the influence of 3-OHBcP on bone metabolism using goldfish. Third, the detailed mechanism of 3-OHBcP on bone metabolism was investigated using zebrafish and goldfish. The LC

Cholinergic transmission underlies higher brain functions such as cognition and movement. To elucidate the process whereby acetylcholine (ACh) release is maintained and regulated in the central nervous system, uptake of [

Ketone bodies, including acetoacetate and β-hydroxybutyrate (βOHB), are produced from acetyl coenzyme A in the liver and then secreted into the blood. These molecules are a source of energy for peripheral tissues during exercise or fasting. βOHB has been reported to inhibit histone deacetylases (HDACs) 1, 3, and 4 in human embryonic kidney 293 cells. Thus, βOHB may regulate epigenetics by modulating HDACs. There have been several reports that the administration of βOHB or induction of a physiological state of ketosis has an antitumor effect; however, the mechanism remains unclear. The aim of this study was to investigate whether βOHB enhances cisplatin-induced apoptosis in hepatocellular carcinoma (HCC) cells by modulating activity and/or expression of HDACs. We found that βOHB significantly enhanced cisplatin-induced apoptosis and cleavage of caspase-3 and -8 in HCC cells. Further, βOHB significantly decreased the expression of HDCA 3/5/6 and survivin in liver hepatocellular (HepG2) cells. In HDAC3/6 gene silencing, survivin expression was significantly decreased, and cisplatin-induced cleavage of caspase-3 was significantly enhanced compared with control in HepG2 cells. In conclusion, βOHB enhanced cisplatin-induced apoptosis via HDAC3/6 inhibition/survivin axis in HepG2 cells, which suggests that βOHB could be a new adjuvant agent for cisplatin chemotherapy. Keywords: Ketone body, β-Hydroxybutyrate, Histone deacetylase, Apoptosis, Survivin

Cyclooxygenase 2 (COX-2) is an inducible rate-limiting enzyme for prostanoid production. Because COX-2 represents one of the inducible genes in mouse mesenchymal stem cells upon differentiation into Leydig cells, we investigated COX-2 expression and production of prostaglandin (PG) in Leydig cells. Although COX-2 was undetectable in mouse testis, it was transiently induced in Leydig cells by human chorionic gonadotropin (hCG) administration. Consistent with the finding that Leydig cells expressed aldo-keto reductase 1B7 (PGF synthase) and PGE synthase 2, induction of COX-2 by hCG caused a marked increase in testicular PGF 2α and PGE 2 levels. Using mouse Leydig cell tumor-derived MA-10 cells as a model, it was indicated by reporter assays and electron mobility shift assays that transcription of the COX-2 gene was activated by CCAAT/enhancer-binding protein β (C/EBPβ) with cAMP-stimulation. C/EBPβ expression was induced by cAMP-stimulation, whereas expression of C/EBP homolog protein (CHOP) was robustly downregulated. Transfection of CHOP expression plasmid inhibited cAMP-induced COX-2 promoter activity. In addition, CHOP reduced constitutive COX-2 expression in other mouse Leydig cell tumor-derived TM3 cells. These results indicate that COX-2 is induced in Leydig cells by activation of C/EBPβ via reduction of CHOP expression upon gonadotropin-stimulation to produce PGF 2α and PGE 2 .

Regulation of neurotransmitter release in the central nervous system is complex. Here, we investigated regulatory mechanisms for acetylcholine (ACh) release from cholinergic neurons by performing superfusion experiments with rat striatal segments after labelling the cellular ACh pool with [3 H]choline. Electrical stimulation-evoked pronounced [3 H]ACh release from cholinergic neurons. The estimated quantity of [3 H]ACh release per pulse of electrical stimulation was reduced by an increase in stimulus frequency, showing an inverse correlation between release probability of ACh and neuronal excitation. ACh release was also negatively regulated by pre-synaptic muscarinic ACh receptors (mAChRs). The autoinhibition induced by released ACh was predominantly suppressed by the M2 -selective antagonist AF-DX 116, partially inhibited by M3 -selective darifenacin, and minimally by M4 -selective PD 102807. Other subtype-selective antagonists had no effect at subtype-selective concentrations. ACh esterase (AChE) inhibitors (diisopropylfluorophosphate, donepezil and galantamine) at concentrations that mostly inhibit esterase activity reduced [3 H]ACh release, and the reduction was abolished by treatment with atropine. This implies that pre-synaptic autoreceptors are activated more after blockade of ACh hydrolysis, leading to autoinhibition of ACh release and consequent reduction in synaptic ACh concentrations. [3 H]efflux was also enhanced by ACh uptake inhibitors (100 μM hemicholinium-3 and physostigmine), regardless of ACh hydrolysis. This study shows that synaptic ACh concentrations in striatal cholinergic neurons are regulated in a complex manner by many factors such as release probability, pre-synaptic M2 /M3 /M4 mAChRs, AChE and post-synaptic ACh uptake, and provides important information about cholinergic neurotransmission for future exploration of therapeutic strategies for Alzheimer's and other central nervous system diseases. OPEN SCIENCE BADGES: This article has received a badge for *Open Materials* because it provided all relevant information to reproduce the study in the manuscript. The complete Open Science Disclosure form for this article can be found at the end of the article. More information about the Open Practices badges can be found at https://cos.io/our-services/openscience-badges/.

Ovaries represent one of the primary steroidogenic organs, producing estrogen and progesterone under the regulation of gonadotropins during the estrous cycle. Gonadotropins fluctuate the expression of various steroidogenesis-related genes, such as those encoding steroidogenic enzymes, cholesterol deliverer, and electronic transporter. Steroidogenic factor-1 (SF-1)/adrenal 4-binding protein (Ad4BP)/NR5A1 and liver receptor homolog-1 (LRH-1) play important roles in these phenomena via transcriptional regulation. With the aid of cAMP, SF-1/Ad4BP and LRH-1 can induce the differentiation of stem cells into steroidogenic cells. This model is a useful tool for studying the molecular mechanisms of steroidogenesis. In this article, we will provide insight into the transcriptional regulation of steroidogenesis-related genes in ovaries that are revealed from stem cell-derived steroidogenic cells. Using the cells derived from the model, novel SF-1/Ad4BP- and LRH-1-regulated genes were identified by combined DNA microarray and promoter tiling array analyses. The interaction of SF-1/Ad4BP and LRH-1 with transcriptional regulators in the regulation of ovarian steroidogenesis was also revealed.

A 59-year-old man with chief complaints of right-sided rib pain and fever was admitted to our hospital. A type 2 tumor in the ascending colon was revealed by total colonoscopy. Computed tomography examination revealed multiple tumors in the liver. The white blood cell count was high as 13,740/μL. Chemotherapy was planned after treatment with antibiotics, but it was not successful. Right colectomy was performed for infection control. mFOLFOX6 therapy was performed, but liver metastases progressed rapidly, and he died on the 39th postoperative day. The immunohistochemistry revealed G-CSF producing colon cancer. G-CSF producing colon cancer progresses rapidly with poor prognosis. It is necessary to think carefully about indication of surgery and chemotherapy.

The number of elderly patients and colorectal cancer patients is increasing, so laparoscopic surgery for colorectal cancer in elderly patients is suspected to increase. In 456 patients who underwent laparoscopic surgery for colorectal cancer, we investigated whether laparoscopic surgery for elderly patients with colon cancer patients could be performed equally compared to non-elderly patients. Preoperative ASA-PS was slightly poorer in elderly patients. There was no significant difference in pStage. The 5-year overall survival rate was lower in the elderly, but there were no significant differences in blood loss, operation time, postoperative hospital stays and incidence of complications of Clavien-Dindo classification grade 3 or higher. It was suggested that laparoscopic surgery for elderly patients with colorectal cancer may be safely performed compared with non-elderly patients.

A 67-year-old man with complaints of upper abdominal pain visited a clinic and was diagnosed with type 3 gastric cancer. Contrasted-enhanced CT revealed gastric wall thickening and extensive metastatic lymph nodes particularly around the celiac artery and also invasion to pancreas. He was diagnosed with cT4b, cN2, cM0, cStage ⅢB and we treated with neoadjuvant chemotherapy(NAC)consisting of 4 courses of S-1 and cisplatin regimen. After the NAC, primary cancer and metastatic lymph nodes were reduced remarkably. A curative operation could be performed and the histopathological examination showed"Grade 3, pathological complete response".

PNU-120596 is a classical positive allosteric modulator (PAM) of α7 nicotinic acetylcholine receptor (α7 nAChR) and widely used to investigate the effect of α7 nAChR activation on several inflammation-associated diseases including rheumatoid arthritis, inflammatory bowel disease and cerebral ischemia. In this study, we report that PNU-120596 directly inhibits p38 mitogen-activated protein kinase (MAPK) activity. In 293A cells, p38 MAPK phosphorylation by several factors (oxidative stress, osmotic stress, TNF-α, or muscarinic stimulation) was inhibited by PNU-120596 as well as p38 MAPK inhibitor BIRB-796. Inhibition of p38 MAPK phosphorylation by PNU-120596 was not affected by α7 nAChR antagonist, methyllycaconitine (MLA). In vitro kinase assay revealed that PNU-120596 directly inhibits p38α MAPK-induced activating transcription factor 2 (ATF2) phosphorylation. MKK6-induced phosphorylation of p38α MAPK was also inhibited by PNU-120596. Real-time monitoring of binding to p38α MAPK using fluoroprobe SKF-86002 showed quite rapid binding of PNU-120596 compared to BIRB-796 which is known as a slow binder. Finally, we showed that PNU-120596 suppressed LPS-induced phosphorylation of p38 MAPK and expression of inflammatory factors including TNF-α, IL-6 and COX-2, independent on α7 nAChR activity in microglial cell BV-2. Thus, PNU-120596 might exert an anti-inflammatory effect through not only α7 nAChR potentiation but also direct inhibition of p38 MAPK.

Aim Endoscopic decompression using the self‐expandable metallic colonic stent (SEMS) or transanal decompression tube (TDT) can convert emergency surgery into elective one‐stage surgery for obstructive colorectal cancer (OCRC). The aim of the present study was to clarify the effect of SEMS and TDT on long‐term oncological outcomes. Methods We retrospectively analyzed 76 consecutive pathological stage II and III OCRC patients who were inserted with SEMS or TDT as a bridge to curative surgery between 2009 and 2018. Results There were 53 SEMS cases and 23 TDT cases. The tumor was located in the left colon in 58 cases and in the right colon in 18 cases. The interval between the decompression and the surgery was 16.5 days in the SEMS group and 13.0 days in the TDT group (P = 0.09). Technical and clinical success rates were 100% and 100% for SEMS, and 95% and 91% for TDT, respectively. Stoma was created in four patients in the SEMS group, and in five in the TDT group (P = 0.08). Three‐year overall survival rates of the SEMS and TDT groups were 82% and 86% (P = 0.94), and disease‐free survival rates were 68% and 62% (P = 0.79), respectively. The recurrence pattern was not significantly different. Conclusion This study found no statistically significant differences between the effects of SEMS and TDT for OCRC as a bridge to surgery on long‐term outcomes.

Background: Hepatocellular carcinoma (HCC) is a major cause of cancer death worldwide and establishment of new chemotherapies for HCC is urgently needed. GPR41 [free fatty acid receptor 3 (FFA3)] is a G protein-coupled receptor for short chain fatty acids, including acetate, propionate, and butyrate. In our previous study, we showed that propionate enhances the cytotoxic effect of cisplatin in HCC cells and that this mechanism is dependent on inhibition of histone deacetylases (HDACs) via GPR41/FFA3. However, the antitumor action of GPR41/FFA3 has not been elucidated. Methods: In this study, we examined AR420626 as a GPR41-selective agonist in HepG2 and HLE cells. Nude mice were used for HepG2 xenograft studies. The apoptotic effect of AR420626 was evaluated using flow cytometry analysis. Expression of apoptosis-related proteins and HDACs was evaluated by Western immunoblot. Gene silencing of HDAC 3/5/7 and GPR41 was performed using small interfering RNA. Expression of TNF-α mRNA was evaluated by TaqMan real-time polymerase chain reaction. Results: We found that AR420626, a selective GPR41/FFA3 agonist, suppressed growth of HepG2 xenografts and inhibited proliferation of HCC cells by inducing apoptosis. AR420626 induced proteasome activation through mTOR phosphorylation, which reduced HDAC proteins, and then increased expression of TNF-α. Conclusion: AR420626, a selective GPR41/FFA3 agonist, may be a candidate as a therapeutic agent for HCC.

Short-chain fatty acids (SCFAs) such as acetate, propionate, and butyrate are generated by microbial fermentation of indigestible fiber by gut flora. SCFAs are ligands of two orphan G protein-coupled receptors, GPR41 and GPR43, that modulate cell proliferation and induce apoptosis. However, it is unclear if SCFAs enhance the effects of chemotherapy in a GPR41- or GPR43-dependent manner. The aim of this study was to investigate whether SCFAs, and particularly propionate, activate GPR41 or GPR43, and thereby enhance the antitumor effects of cisplatin in HepG2 human hepatocellular carcinoma (HCC) cells. The inhibitory effects of propionate and cisplatin on proliferation of HCC cells were determined by MTS assay. Changes in apoptosis rate were analyzed by flow cytometry. The effects of combined propionate and cisplatin on these properties in HCC cells were significantly higher than those of cisplatin alone. With combined treatment, the levels of cleaved caspase-3, active caspase-3 forms, and acetylated histone H3 were enhanced in a GPR41-dependent manner; expression of histone deacetylases (HDAC) 3, 4, 5, 6, 8 proteins was significantly reduced; and induction of TNF-α expression was significantly enhanced. These results suggest that propionate and cisplatin synergistically and significantly induce apoptosis of HepG2 cells by increasing expression of autocrine TNF-α via reduction of HDACs through GPR41 signaling. From clinical and translational perspectives, our data suggest that a combination of propionate with cisplatin may have better therapeutic effects on HCC compared with conventional treatment, and that a selective GPR41 agonist may be a candidate as an adjuvant therapeutic agent for HCC.

17β-Hydroxysteroid dehydrogenases (17β-HSDs, HSD17B) catalyze the reduction of 17-ketosteroids and the oxidation of 17β-hydroxysteroids to regulate the production of sex steroids. Among HSD17B family, 17β-HSD type 3 (HSD17B3) is expressed in testicular Leydig cells and contributes to development of male sexual characteristics by converting androstenedione (A4) to testosterone (T). Mutations of HSD17B3 genes cause a 46,XY disorder of sexual development (46,XY DSD) as a result of low T production. Therefore, the evaluation of HSD17B3 enzymatic activity is important for understanding and diagnosing this disorder. Although various amino acid substitutions of HSD17B3 have been reported in previous studies, the enzymatic activities of these proteins were often not defined. This is probably due to the difficulties that such enzymatic activities have been evaluated by quantifying the conversion of A4 into T using radioactive isotopes and liquid chromatography-mass spectrometry-mass spectrometry (LC-MS/MS). We adapted a method that easily evaluates enzymatic activity of HSD17B3 proteins by quantifying the conversion from A4 to T using androgen receptor (AR)-mediated transactivation. HEK293 cells were transfected to express human HSD17B3, and incubated medium containing A4. Depending on the incubation time with HSD17B3-expressing cells, the culture media progressively increased luciferase activities in CV-1 cells, transfected with the AR expression vector and androgen-responsive reporter. These luciferase activities reflected T concentrations in culture media defined by LC-MS/MS. This system is also applicable to detect the conversion of A4 to T by HSD17B1 and HSD17B5. In addition, it can evaluate the conversion of 11-ketoandrostenedione to 11-ketotestosterone by HSD17B family. Establishment of HEK293 cells expressing various missense mutations in the HSD17B3 gene with (N74T, A188V, M197K, A200V,, V225M, H271R) or without (V31I, E67K and G289S) the manifestation of 46,XY DSD revealed that this system is effective to evaluate the enzymatic activities of mutant proteins. A188V, A200V, V225M and H271R mutations completely inactivated the enzymatic function. N74T and M197K mutations showed some residual activities. In contrast, V31I, E67K and G289S substitutions showed similar activities as the wild-type protein.