Oral Health and Swallowing Function of Nursing Home Residents.

OBJECTIVE: Although a good oral environment helps reduce the risk of pneumonia in the elderly, repeated pneumonia can occur even with frequent oral care. The actual risk of pneumonia during oral intake, the choice of whether oral intake is possible, and the choice of food form are often determined using video fluorography (VF), which can provide detailed information on swallowing function. However, few reports have compared the oral environment and swallowing function, leaving the relationship unclear. We examined the relationship between the oral environment and swallowing function and the characteristics of swallowing function in elderly nursing home residents. METHODS: The subjects were 48 elderly nursing home residents (13 males, 35 females) with a mean age of 89 years who underwent outpatient or inpatient evaluation of their oral environment and swallowing function. There were three groups of residents: those who were evaluated for swallowing as outpatients, those who were hospitalised for pneumonia, and those who were hospitalised for diseases other than pneumonia. The oral environment was assessed by a dentist or dental hygienist using the Oral Health Assessment Tool (OHAT). Swallowing function was assessed by an otorhinolaryngologist using VF. RESULTS: There was no correlation between OHAT and VF scores in the outpatient group or the group hospitalised for pneumonia, but there was a correlation in the group hospitalised for reasons other than pneumonia. CONCLUSION: In facilities with good oral care, the development of pneumonia may be related to factors other than the oral environment and the OHAT may reflect conditions other than swallowing function. The swallowing function of nursing home residents should be evaluated by VF, which allows observation of all stages of swallowing.

Outpatient Treatment of Mild Dysphagia in Ear-Nose-and-Throat Clinics.

OBJECTIVE: Many reports on inpatient dysphagia rehabilitation in acute and convalescent rehabilitation hospitals exist, but there are a few reports on outpatient treatments. Otolaryngologists still take a trial-and-error approach when treating dysphagia. Here, we explore the effectiveness and limitations of outpatient treatment in ear-nose-and-throat (ENT) clinics. METHODS: Sixty-four patients (41 males and 23 females) aged 27-101 years (mean 78 years) visited an outpatient clinic specialising in feeding and swallowing conditions (the Fukuyo ENT Clinic). All were able to perform the activities of daily living (ADL) to the extent that outpatient visits were possible; no home visits were made. The weekly outpatient day was staffed by an otolaryngologist and a speech-language-hearing therapist (SLHT). All patients were subjected to fibreoptic endoscopic evaluation of swallowing (FEES), followed by appropriate training as revealed by the examinations. RESULTS: Salivary retention in the glottis valley and piriform sinuses improved (both p < 0.05) in 30 patients who underwent repeat FEES; we compared the initial and final figures. In 14 cases in whom maximal tongue pressure (TP) was measured, this was higher at the final than at the first examination (p < 0.01). CONCLUSION: Outpatient treatment at ENT clinics for patients who are able to maintain their ADLs to the extent that they are able to walk to a hospital is an option for the treatment of age-related dysphagia. For severe cases, however, house calls and collaboration with the home and nursing care sector will be necessary and should be considered in the future.

Effects of Food Properties and Aging on External Auditory Canal Movements Associated With Mastication.

Few objective evaluations of external auditory canal movement during mastication have been conducted. This study investigated the extent to which age and physical properties influence such movement. The effects of food properties and aging on ear canal movement during mastication were investigated using an earable reliable chewing-count measurement device. We used such a device to study the effects of food properties and aging on ear canal movement associated with mastication. A main effect of the difference in hardness between the foods (F = 8.3405, p = 0.0071) was found. No interaction (F = 1.3558, p = 0.2534) or main effect of age (F = 1.1206, p = 0.2982) was found. The values for peanuts were higher than those for pudding. Age had no significant effect. For both pudding and peanuts, there was a trend toward greater ear canal movement in young adults than in older adults. We suggest that external auditory canal movement during mastication decreases as muscle function declines with aging, but any effect may be less than that exerted by food properties.

Inhibitory Effect of Pyra-Metho-Carnil on Cancer Spheroid Growth Through Decrease in Glycolysis-associated Molecules.

BACKGROUND/AIM: Pyra-Metho-Carnil (PMC) has been identified as a novel candidate compound for treating numerous malignancies; however, its mechanism of action remains unknown. In this study, we conducted RNA-sequencing (RNA-seq) analyses to elucidate the mechanism of PMC against human colorectal cancer cells harboring mutant KRAS (mtKRAS). MATERIALS AND METHODS: RNA-seq analyses of the HKe3-wild-type KRAS and HKe3-mtKRAS spheroids treated with DMSO or PMC for 6 days were performed. RESULTS: RNA-seq data suggested that PMC treatment suppresses the aerobic glycolysis pathway in HKe3-mtKRAS spheroids through the down-regulation of the HIF1 pathway. Indeed, treatment with PMC markedly suppresses the absorption of glucose by spheroids and the secretion of lactate from them. CONCLUSION: PMC suppresses growth of cancer spheroid through down-regulation of cancer-specific glucose metabolism.

Association Between Oral Health and Swallowing Function in the Elderly.

Objective: Although the oral environment significantly affects the risk of pneumonia, there have been few studies regarding its relation with swallowing. There is no doubt that there is a significant link between the oral environment and the development of pneumonia; however, there have been few comparative studies of swallowing using video endoscopy (VE) and video fluorography (VF) as indicators to determine the actual availability of oral intake and the choice of food form. This study was performed to examine whether the oral environment or swallowing function contributes more to the development of pneumonia in the elderly. Methods: The study population consisted of 24 patients (7 men and 17 women; age range: 64-97 years; average age: 86 years) assessed using the Oral Health Assessment Tool (OHAT), VE and VF at Fukuoka Dental College Hospital. The most common disease was pneumonia (17 patients), followed by cerebral infarction (5 patients), pyelonephritis (4 patients), bronchitis (2 patients), Parkinson's disease (2 patients), scleroderma (1 patient), diabetes (1 patient), eosophageal cancer (1 patient) and Parkinson's syndrome> (1 patient). Some patients had multiple diseases. Oral intake was possible in 20 patients (80%), whereas tube feeding and gastric banding were required in 4 patients. Results: The OHAT score was not correlated with either the VE or VF score. Furthermore, the OHAT score was not significantly different between the multiple- and no/single-pneumonia episode groups. The group with multiple episodes of pneumonia had lower VE and VF scores than those with no or only a single episode of pneumonia. Conclusion: Oral assessment, VE and VF are necessary to evaluate swallowing in patients with suspected dysphagia. Swallowing function, especially as assessed by VE and VF, is more important than examination of the oral environment for evaluating risk of recurrent aspiration pneumonia in the elderly. In addition, multiple factors contribute to recurrent pneumonia in patients with a good oral environment, including subclinical aspiration, pharyngeal clearance and delayed activation of the gag reflex.

A Potential Novel Treatment for Chronic Cough in Long COVID Patients: Clearance of Epipharyngeal Residual SARS-CoV-2 Spike RNA by Epipharyngeal Abrasive Therapy.

A major target of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the epipharyngeal mucosa. Epipharyngeal abrasive therapy (EAT) is a Japanese treatment for chronic epipharyngitis. EAT is a treatment for chronic epipharyngitis in Japan that involves applying zinc chloride as an anti-inflammatory agent to the epipharyngeal mucosa. Here, we present a case of a 21-year-old man with chronic coughing that persisted for four months after a diagnosis of mild coronavirus disease 2019 (COVID-19), who was treated by EAT. We diagnosed chronic epipharyngitis as the cause of the chronic cough after the SARS-CoV-2 infection. SARS-CoV-2 spike RNA had persisted in the epipharyngeal mucosa of this Long COVID patient. EAT was performed once a week for three months, which eliminated residual SARS-CoV-2 RNA and reduced epipharyngeal inflammation. Moreover, a reduction in the expression of proinflammatory cytokines was found by histopathological examination. We speculate that the virus was excreted with the drainage induced by EAT, which stopped the secretion of proinflammatory cytokines. This case study suggests that EAT is a useful treatment for chronic epipharyngitis involving long COVID.

Epipharyngeal Abrasive Therapy Down-regulates the Expression of Cav1.2: A Key Molecule in Influenza Virus Entry.

BACKGROUND/AIM: Influenza A virus (IAV) infection causes an inflammatory response to the respiratory mucosa. The viral glycoprotein hemagglutinin (HA) binds to the sialylated voltage-dependent Ca2+ channel (Cav1.2) in ciliated epithelium. The binding of HA and sialylated Cav1.2 is considered essential to IAV infection, entry, and IAV-induced Ca2+ oscillation. The epipharynx comprises the ciliated epithelium, which is the initial target for viruses that cause upper respiratory tract infections. Previously, we showed that epipharyngeal abrasive therapy (EAT), a treatment for chronic epipharyngitis in Japan, which scratches the epipharyngeal mucosa with a cotton swab containing zinc chloride, induces squamous metaplasia. In this study, we evaluated whether squamous metaplasia by EAT affects the expression patterns of Cav1.2. PATIENTS AND METHODS: The study subjects were seven patients who had not been treated with EAT and 11 patients who had. For the immunohistochemical assessment of the epipharyngeal mucosa, the staining intensity of Cav1.2 was described using the immunohistochemical score (IHC score). RESULTS: The IHC scores for Cav1.2 in the EAT-treated group was 4.19-fold lower than those in the non-treated group (p=0.0034). CONCLUSION: EAT down-regulates the expression of Cav1.2, a key cell surface molecule in influenza virus entry via squamous metaplasia. Thus, EAT may be a simple method for preventing influenza infection.

Epipharyngeal Abrasive Therapy (EAT) Reduces the mRNA Expression of Major Proinflammatory Cytokine IL-6 in Chronic Epipharyngitis.

The epipharynx, located behind the nasal cavity, is responsible for upper respiratory tract immunity; however, it is also the site of frequent acute and chronic inflammation. Previous reports have suggested that chronic epipharyngitis is involved not only in local symptoms such as cough and postnasal drip, but also in systemic inflammatory diseases such as IgA nephropathy and myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) and Long COVID. Epipharyngeal Abrasive Therapy (EAT), which is an effective treatment for chronic epipharyngitis in Japan, is reported to be effective for these intractable diseases. The sedation of chronic epipharyngitis by EAT induces suppression of the inflammatory cytokines and improves systemic symptoms, which is considered to be one of the mechanisms, but there is no report that has proved this hypothesis. The purpose of this study was to clarify the anti-inflammatory effect of EAT histologically. The study subjects were 8 patients who were not treated with EAT and 11 patients who were treated with EAT for chronic epipharyngitis for 1 month or more. For immunohistochemical assessment, the expression pattern of IL-6 mRNA, which plays a central role in the human cytokine network, was analyzed using in situ hybridization. The expression of IL-6 in the EAT-treated group was significantly lower than those in the EAT nontreated group (p = 0.0015). In addition, EAT suppressed the expression of tumor necrosis factor alpha (TNFα), a crucial proinflammatory cytokine. As a result, continuous EAT suppressed submucosal cell aggregation and reduced inflammatory cytokines. Thus, EAT may contribute to the improvement of systemic inflammatory diseases through the suppression of IL-6 expression.

Cancer Spheroid Proliferation Is Suppressed by a Novel Low-toxicity Compound, Pyra-Metho-Carnil, in a Context-independent Manner.

BACKGROUND/AIM: In a screen of compounds to selectively suppress the growth of cancer spheroids, which contained mutant (mt) KRAS, NPD10621 was discovered and associated derivatives were investigated. MATERIALS AND METHODS: Spheroid areas from HCT116-derived HKe3 spheroids expressing wild type (wt) KRAS (HKe3-wtKRAS) and mtKRAS (HKe3-mtKRAS) were treated with 12 NPD10621 derivatives and measured in three-dimensional floating (3DF) cultures. Several cancers were treated with NPD1018 (pyra-metho-carnil: PMC) in 3DF cultures. In a nude mouse assay, 50% cell growth inhibition (GI50) values were determined. RESULTS: From these 12 derivatives, PMC was the most effective inhibitor of HKe3-mtKRAS spheroid growth with the least toxicity. Furthermore, PMC-mediated growth suppression was observed in all tested cancer cell lines, independent of tissue context, driver gene mutations, and drug resistance, suggesting that the PMC target(s) was crucial for cancer growth in a context-independent manner. The GI50 value of PMC in nude mice assay was 7.7 mg/kg and nude mice that were administered 40 mg/kg PMC for 7 days did not show any abnormal blood cell count values. CONCLUSION: PMC is a low-toxicity compound that inhibits the growth of different tumor cell types.

Epipharyngeal Abrasive Therapy (EAT) Has Potential as a Novel Method for Long COVID Treatment.

COVID-19 often causes sequelae after initial recovery, referred to collectively as long COVID. Long COVID is considered to be caused by the persistence of chronic inflammation after acute COVID-19 infection. We found that all long COVID patients had residual inflammation in the epipharynx, an important site of coronavirus replication, and some long COVID symptoms are similar to those associated with chronic epipharyngitis. Epipharyngeal abrasive therapy (EAT) is a treatment for chronic epipharyngitis in Japan that involves applying zinc chloride as an anti-inflammatory agent to the epipharyngeal mucosa. In this study, we evaluated the efficacy of EAT for the treatment of long COVID. The subjects in this study were 58 patients with long COVID who were treated with EAT in the outpatient department once a week for one month (mean age = 38.4 ± 12.9 years). The intensities of fatigue, headache, and attention disorder, which are reported as frequent symptoms of long COVID, were assessed before and after EAT using the visual analog scale (VAS). EAT reduced inflammation in the epipharynx and significantly improved the intensity of fatigue, headache, and attention disorder, which may be related to myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). These results suggest that EAT has potential as a novel method for long COVID treatment.

Epipharyngeal Abrasive Therapy Down-regulates the Expression of SARS-CoV-2 Entry Factors ACE2 and TMPRSS2.

BACKGROUND: The epipharynx, with its high expression of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) entry factors angiotensin-converting enzyme 2 (ACE2) and transmembrane protease, serine 2 (TMPRSS2), is a primary target for SARS-CoV-2 replication in the early stage of Coronavirus Disease 19 (COVID-19). Epipharyngeal abrasive therapy (EAT) is a treatment for epipharyngitis in Japan which involves applying zinc chloride to the epipharyngeal mucosa. In this study, we evaluated the expression patterns of ACE2 and TMPRSS2 in tissue samples from patients before and after EAT. PATIENTS AND METHODS: The study subjects were seven patients that had not been treated with EAT and 11 patients that had. For immunohistochemical assessment of the epipharyngeal mucosa, the staining intensity of ACE2 and TMPRSS2 was described as an immunohistochemical score (IHC score). RESULTS: The IHC scores for ACE2 and TEMPRSS2 in the EAT-treated group were 3.40-fold and 1.81-fold lower, respectively, than those in the non-treated group (p=0.0208 and p=0.0244, respectively). CONCLUSION: EAT down-regulates the expression of SARS-CoV-2 entry factors ACE2 and TMPRSS2. Thus, EAT has potential as a novel COVID-19 preventative method.

Growth Suppression of Cancer Spheroids With Mutated KRAS by Low-toxicity Compounds from Natural Products.

BACKGROUND/AIM: Among compounds from natural products selectively suppressing the growth of cancer spheroids, which have mutant (mt) KRAS, NP910 was selected and its derivatives explored. MATERIALS AND METHODS: The area of HKe3 spheroids expressing wild type (wt) KRAS (HKe3-wtKRAS) and mtKRAS (HKe3-mtKRAS) were measured in three-dimensional floating (3DF) cultures treated with 18 NP910 derivatives. The 50% cell growth inhibition (GI50) was determined by long-term 3DF (LT3DF) culture and nude mice assay. RESULTS: We selected NP882 (named STAR3) as the most effective inhibitor of growth of HKe3-mtKRAS spheroids with the least toxicity among NP910 derivatives. GI50s of STAR3 in LT3DF and nude mice assay were 6 µM and 30.75 mg/kg, respectively. However, growth suppression by STAR3 was observed in 50% of cell lines independent of KRAS mutation, suggesting that the target of STAR3 was not directly associated with KRAS mutation and KRAS-related signals. CONCLUSION: STAR3 is a low-toxicity compound that inhibits growth of certain tumour cells.

The transcriptional regulator Zfat is essential for maintenance and differentiation of the adipocytes.

Adipocytes play crucial roles in the control of whole-body energy homeostasis. Differentiation and functions of the adipocytes are regulated by various transcription factors. Zfat (zinc-finger protein with AT-hook) is a transcriptional regulator that controls messenger RNA expression of specific genes through binding to their transcription start sites. Here we report important roles of Zfat in the adipocytes. We establish inducible Zfat-knockout (Zfat iKO) mice where treatment with tamoxifen causes a marked reduction in Zfat expression in various tissues. Tamoxifen treatment of Zfat iKO mice reduces the white adipose tissues (WATs) mass, accompanied by the decreased triglyceride levels. Zfat is expressed in both the adipose-derived stem cells (ADSCs) and mature adipocytes in the WATs. In ex vivo assays of the mature adipocytes differentiated from the Zfat iKO ADSCs, loss of Zfat in the mature adipocytes reduces the triglyceride levels, suggesting cell autonomous roles of Zfat in the maintenance of the mature adipocytes. Furthermore, we identify the Atg13, Brf1, Psmc3, and Timm22 genes as Zfat-target genes in the mature adipocytes. In contrast, loss of Zfat in the ADSCs impairs adipocyte differentiation with the decreased expression of C/EBPα and adiponectin. Thus, we propose that Zfat plays crucial roles in maintenance and differentiation of the adipocytes.

Mutant KRAS Promotes NKG2D+ T Cell Infiltration and CD155 Dependent Immune Evasion.

BACKGROUND/AIM: Roles for mutant (mt) KRAS in the innate immune microenvironment in colorectal cancer (CRC) were explored. MATERIALS AND METHODS: Human CRC HCT116-derived, mtKRAS-disrupted (HKe3) cells that express exogenous mtKRAS and allogenic cytokine-activated killer (CAK) cells were co-cultured in 3D floating (3DF) culture. The anti-CD155 antibody was used for function blocking and immuno histochemistry. RESULTS: Infiltration of CAK cells, including NKG2D+ T cells, into the deep layer of HKe3-mtKRAS spheroids, was observed. Surface expression of CD155 was found to be up-regulated by mtKRAS in 3DF culture and CRC tissues. Further, the number of CD3+ tumor-infiltrating cells in the invasion front that show substantial CD155 expression was significantly larger than the number showing weak expression in CRC tissues with mtKRAS. CD155 blockade decreased the growth of spheroids directly and indirectly through the release of CAK cells. CONCLUSION: CD155 blockade may be useful for therapies targeting tumors containing mtKRAS.

MK615 Suppresses Hypoxia Tolerance by Up-regulation of E-cadherin in Colorectal Cancer Cells With Mutant KRAS.

BACKGROUND/AIM: The Japanese apricot "Prunus mume" is a traditional Japanese medicine. MK615, a compound extract from Prunus mume has been reported to have anti-tumor effects. Herein, we used 3D floating (3DF) culture to evaluate the anticancer effects of MK615 against human colorectal cancer (CRC) cells that contain mutant (mt) KRAS. MATERIALS AND METHODS: HKe3 cells exogenously expressing mtKRAS (HKe3-mtKRAS) were treated with MK615 in 3DF cultures. The protein levels of hypoxia-inducible factor 1 (HIF-1) and E-cadherin were quantified by western blotting. RESULTS: MtKRAS enhanced hypoxia tolerance via up-regulation of HIF-1. The expression of HIF-1 protein was suppressed by constitutive overexpression of E-cadherin in CRC HCT116 spheroids. MK615 increased the expression of E-cadherin and decreased the expression of HIF-1 in HKe3-mtKRAS. These results suggest that MK615 suppresses hypoxia tolerance by up-regulation of E-cadherin in CRC cells with mtKRAS. CONCLUSION: MK615 exhibits properties useful for the potential treatment of CRC patients with mtKRAS.

Zfat Is Indispensable for the Development of Erythroid Cells in the Fetal Liver.

BACKGROUND/AIM: In mice, fetal liver is the first tissue of definitive erythropoiesis for definitive erythroid expansion and maturation. ZFAT, originally identified as a candidate susceptibility gene for autoimmune thyroid disease, has been reported to be involved in primitive hematopoiesis and T cell development. The aim of this study was to examine whether or not Zfat is involved in definitive erythropoiesis in the fetal liver during mammalian development. MATERIALS AND METHODS: The role of Zfat during mouse fetal erythropoiesis in the fetal liver was examined using tamoxifen-inducible CreERT2 Zfat-deficient mice. RESULTS: Zfat-deficient mice exhibit moderate anemia with small and pale fetal liver through a decreased number of erythroblasts by E12.5. Apoptosis sensitivity in fetal liver erythroid progenitors was enhanced by Zfat-deficiency ex vivo. Moreover, Zfat knockdown partially inhibited CD71-/lowTer119- to CD71highTer119- transition of fetal liver erythroid progenitors with impairment in the elevation of CD71 expression. CONCLUSION: Zfat plays a critical role for erythropoiesis in the fetal liver.

Zfat expression in ZsGreen reporter gene knock­in mice: Implications for a novel function of Zfat in definitive erythropoiesis.

Zinc finger and AT­hook domain containing (Zfat) is a transcriptional regulator harboring an AT­hook domain and 18 repeats of a C2H2 zinc­finger motif, which binds directly to the proximal region of transcription start sites in Zfat­target genes. It was previously reported that deletion of the Zfat gene in mice yields embryonic lethality by embryonic day 8.5 and impairs primitive hematopoiesis in yolk sac blood islands. In addition, Zfat has been reported to be involved in thymic T­cell development and peripheral T­cell homeostasis. In the present study, in order to obtain a precise understanding of the expression and function of Zfat, a knock­in mouse strain (ZfatZsG/+ mice), which expressed ZsGreen in the Zfat locus, was established. ZsGreen signals in tissues and cells of ZfatZsG/+ mice were examined by flow cytometric and histological analyses. Consistent with our previous studies, ZsGreen signals in ZfatZsG/+ mice were detected in the embryo and yolk sac blood islands, as well as in thymocytes, B and T cells. In the ZfatZsG/+ thymus, ZsGreen+ cells were identified not only in T­cell populations but also in thymic epithelial cells, suggesting the role of Zfat in antigen­presenting cells during thymic T­cell development. ZsGreen signals were observed in definitive erythroid progenitor cells in the fetal liver and adult bone marrow of ZfatZsG/+ mice. The proportion of ZsGreen+ cells in these tissues was highest at the early stage of erythroid differentiation, suggesting that Zfat serves particular roles in definitive erythropoiesis. Histological studies demonstrated that ZsGreen signals were detected in the pyramidal cells in the hippocampal CA1 region and the Purkinje cells in the cerebellum, suggesting novel functions of Zfat in nervous tissues. Taken together, these results indicated that the ZfatZsG/+ reporter mouse may be considered a useful tool for elucidating the expression and function of Zfat.

Growth Suppression of Human Colorectal Cancer Cells with Mutated KRAS by 3-Deaza-cytarabine in 3D Floating Culture.

BACKGROUND/AIM: During screening for compounds that selectively suppress growth of human colorectal cancer (CRC) spheroids with mutant (mt) KRAS, the uridine analogue, 5-bromouridine (BrUrd) was identified and its derivatives were explored. MATERIALS AND METHODS: DNA incorporation in two-dimensional (2D) and three-dimensional floating (3DF) cultures was examined with the uridine analogue, 5-ethynyl-2'-deoxyuridine (EdU). The area of HKe3 CRC spheroids expressing wild type (wt) KRAS (HKe3-wtKRAS) and mtKRAS (HKe3-mtKRAS) were measured in 3DF culture with 11 BrUrd derivatives. RESULTS: EdU was strongly incorporated into newly-synthesized DNA from HKe3-mtKRAS cells compared to HKe3-wtKRAS in 2D and 3DF culture. 3-Deaza-cytarabine, which has properties of BrUrd and cytidine, was the most effective inhibitor of HKe3-mtKRAS spheroids with the least toxicity to HKe3-wtKRAS. Growth suppression of 3-deaza-cytarabine was stronger than cytarabine in 2D culture, and toxicity was lower than gemcitabine in long-term 3DF culture. CONCLUSION: 3-Deaza-cytarabine exhibits properties useful for the treatment of CRC patients with mtKRAS.

ROS-induced cleavage of NHLRC2 by caspase-8 leads to apoptotic cell death in the HCT116 human colon cancer cell line.

Excess production of reactive oxygen species (ROS) is known to cause apoptotic cell death. However, the molecular mechanisms whereby ROS induce apoptosis remain elusive. Here we show that the NHL-repeat-containing protein 2 (NHLRC2) thioredoxin-like domain protein is cleaved by caspase-8 in ROS-induced apoptosis in the HCT116 human colon cancer cell line. Treatment of HCT116 cells with the oxidant tert-butyl hydroperoxide (tBHP) induced apoptosis and reduced NHLRC2 protein levels, whereas pretreatment with the antioxidant N-acetyl-L-cysteine prevented apoptosis and the decrease in NHLRC2 protein levels seen in tBHP-treated cells. Furthermore, the ROS-induced decrease in NHLRC2 protein levels was relieved by the caspase inhibitor z-VAD-fmk. We found that the thioredoxin-like domain of NHLRC2 interacted with a proenzyme form of caspase-8, and that caspase-8 cleaved NHLRC2 protein at Asp580 in vitro. Furthermore, siRNA-mediated knockdown of caspase-8 blocked the ROS-induced decrease in NHLRC2 protein levels. Both shRNA and CRISPR-Cas9-mediated loss of NHLRC2 resulted in an increased susceptibility of HCT116 cells to ROS-induced apoptosis. These results suggest that excess ROS production causes a caspase-8-mediated decrease in NHLRC2 protein levels, leading to apoptotic cell death in colon cancer cells, and indicate an important role of NHLRC2 in the regulation of ROS-induced apoptosis.

Apremilast Induces Apoptosis of Human Colorectal Cancer Cells with Mutant KRAS.

BACKGROUND/AIM: We previously reported the crucial roles of oncogenic Kirsten rat sarcoma viral oncogene homologue (KRAS) in inhibiting apoptosis and disrupting cell polarity via the regulation of phosphodiesterase type 4B2 (PDE4B2) expression in human colorectal cancer (CRC) HCT116 cells in a three-dimensional culture (3DC). Here, we evaluated the effects of apremilast, a selective PDE4 inhibitor, on luminal apoptosis in 3DC and nude mice assay using HKe3 human CRC cells stably expressing wild-type (wt)PDE4B2 (HKe3-wtPDE4B2), mutant (mt)PDE4B2 (kinase dead) (HKe3-wtKRAS), wtKRAS (HKe3-wtKRAS) and mtKRAS (HKe3-mtKRAS). MATERIALS AND METHODS: Apoptosis was detected by immunofluorescence using confocal laser scanning microscopy or western blot in HKe3-wtPDE4B2, HKe3-mtPDE4B2, HKe3-wtKRAS and mtKRAS cells treated with or without apremilast in 3DC. Tumourigenicity was assessed in nude mice assay using these cells. RESULTS: Apremilast did not inhibit the proliferation of HKe3-wtPDE4B2 cells or HKe3-mtKRAS in two-dimensional cultures, whereas the number of apoptotic HKe3-wtPDE4B2 cells and HKe3-mtKRAS cells increased after apremilast treatment in 3DC, leading to formation of a luminal cavity. Tumour growth in nude mice was dramatically reduced by intraperitoneal injection of apremilast. Notably, a decreased level of caspase-1 expression was observed in HKe3-wtPDE4B2 and HKe3-mtKRAS cells. CONCLUSION: Apremilast induces tumour regression in nude mice, possibly by inducing caspase-1 expression.