Acid-sensing receptor GPR4 plays a crucial role in lymphatic cancer metastasis

Cancer tissues exhibit an acidic microenvironment owing to the accumulation of protons and lactic acid produced by cancer and inflammatory cells. To examine the role of an acidic microenvironment in lymphatic cancer metastasis, gene expression profiling was conducted using human dermal lymphatic endothelial cells (HDLECs) treated with a low pH medium. Microarray and gene set enrichment analysis revealed that acid treatment induced the expression of inflammation-related genes in HDLECs, including genes encoding chemokines and adhesion molecules. Acid treatment-induced chemokines C-X3-C motif chemokine ligand 1 (CX3CL1) and C-X-C motif chemokine ligand 6 (CXCL6) autocrinally promoted the growth and tube formation of HDLECs. The expression of vascular cell adhesion molecule 1 (VCAM-1) increased in HDLECs after acid treatment in a time-dependent manner, which, in turn, enhanced their adhesion to melanoma cells. Among various acid-sensing receptors, HDLECs basally expressed G protein-coupled receptor 4 (GPR4), which was augmented under the acidic microenvironment. The induction of chemokines or VCAM-1 under acidic conditions was attenuated by GPR4 knockdown in HDLECs. In addition, lymph node metastases in a mouse melanoma model were suppressed by administering an anti-VCAM-1 antibody or a GPR4 antagonist. These results suggest that an acidic microenvironment modifies the function of lymphatic endothelial cells via GPR4, thereby promoting lymphatic cancer metastasis. Acid-sensing receptors and their downstream molecules might serve as preventive or therapeutic targets in cancer.

Loss of Dec1 inhibits alcohol-induced hepatic lipid accumulation and circadian rhythm disorder

Chronic alcohol exposure increases liver damage such as lipid accumulation and hepatitis, resulting in hepatic cirrhosis. Chronic alcohol intake is known to disturb circadian rhythms in humans and animals. DEC1, a basic helix-loop-helix transcription factor, plays an important role in the circadian rhythm, inflammation, immune responses, and tumor progression. We have previously shown that Dec1 deficiency inhibits stresses such as periodontal inflammation and perivascular fibrosis of the heart. However, the significance of Dec1 deficiency in chronic alcohol consumption remains unclear. In the present study, we investigated whether the biological stress caused by chronic alcohol intake is inhibited in Dec1 knockout mice. We treated control and Dec1 knockout mice for three months by providing free access to 10% alcohol. The Dec1 knockout mice consumed more alcohol than control mice, however, we observed severe hepatic lipid accumulation and circadian rhythm disturbance in control mice. In contrast, Dec1 knockout mice exhibited little effect on these outcomes. We also investigated the expression of peroxisome proliferator-activated receptors (PPARs) and AMP-activated protein kinase (AMPK), which are involved in the regulation of fatty acid metabolism. Immunohistochemical analysis revealed increases of phosphorylation AMPK and PPARa but decreases PPARg in Dec1 knockout mice compared to that in control mice. This indicates a molecular basis for the inhibition of hepatic lipid accumulation in alcohol-treated Dec1 knockout mice. These results suggest a novel function of Dec1 in alcohol-induced hepatic lipid accumulation and circadian rhythm disorders.

Histological analysis of a Becker muscular dystrophy case, diurnal expression of dystrophin in control mice and decreased expression of dystrophin in Bmal1 knockout mice

Becker muscular dystrophy (BMD) is a hereditary disease characterized by dystrophin deletion that consequently induces muscle weakness, cardiac hypertrophy and cardiac failure; These conditions are similar to those in Duchenne muscular dystrophy. The circadian rhythm is a physiological phenomenon that is predominantly regulated by the transcription and translation of clock genes. Bmal1 (Brain and muscle Arnt-like protein 1) is one of the core clock genes, and its deficiency disturbs the circadian rhythm, results in cardiac hypertrophy and cardiac failure. Dystrophin expression under diurnal conditions and in Bmal1 deficiency is yet to be elucidated. In this study, we analyzed the heart and lungs sampled during a BMD autopsy. Macroscopical examination revealed a large heart and dilated cardiomyopathy. Microscopical examination revealed an undulated structure, as well as the degeneration, and necrosis of myocardial cells. We also analyzed dystrophin expression in tissues obtained from human autopsies and mice. In human autopsy cases, dystrophin expression was lower in the heart with BMD compared that in the heart with non-BMD hypertrophy. In the heart and muscle of control mice, dystrophin expression was higher at ZT0 than at ZT12. The dystrophin expression was found to be lower in heart-specific Bmal1 knockout mice compared to that in the control mice. Hence, our study indicated that BMD was closely associated with cardiac hypertrophy and cardiac failure, while dystrophin had a diurnal expression pattern in control mice that was regulated by Bmal1.

Differential immunohistochemical expression of DEC1, CK‑1ε, and CD44 in oral atypical squamous epithelium and carcinoma in situ

Presence of nuclear atypia during histological investigation is often a cause of concern for pathologists while identifying tumor and non-tumor cells in a biopsy sample of oral mucosa. Nuclear atypia is observed in severe inflammation, ulcers and reactive changes. Therefore, additional methods, such as immunohistochemistry, may help precise diagnosis. When the atypia is suggestive of tumorous or reactive origin, the lesion is diagnosed as atypical squamous epithelium (ASE). When there is severe nuclear atypia in the mucosa, such as in disorders of nuclear polarity, large nuclei, and clear nucleolus, the lesion is diagnosed as carcinoma in situ (CIS). However, it is not easy to distinguish ASE and CIS using hematoxylin and eosin staining. The present study aimed to distinguish ASE from CIS using immunohistochemistry. A total of 32 biopsy samples of either ASE or CIS cases were selected and the level of casein kinase 1ε (CK-1ε), differentiated embryonic chondrocyte gene 1 (DEC1), proliferating cell nuclear antigen (PCNA) and CD44, which are four protein markers which have been previously linked to cancer progression, were analyzed. CK-1ε and CD44 expression was higher in CIS samples than in ASE samples. However, DEC1 expression was lower in CIS samples than in ASE samples. PCNA expression was not markedly different between the two groups. Additionally, it was found that DEC1-overexpressing cells had decreased levels of CK-1ε and CD44 compared with control cells, while CK-1ε-overexpressing cells had relatively unchanged levels of CD44, DEC1 and PCNA. These results suggested that DEC1 negatively regulates the expression of CK-1ε and CD44. Thus, DEC1, CK-1ε, and CD44 were identified as mechanistically linked and clinically relevant protein biomarkers, which could help distinguish ASE and CIS.

Exposure to Cigarette Smoke Enhances Pneumococcal Transmission Among Littermates in an Infant Mouse Model

Streptococcus pneumoniae, one of the most common commensal pathogens among children, is spread by close contact in daycare centers or within a family. Host innate immune responses and bacterial virulence factors promote pneumococcal transmission. However, investigations into the effects of environmental factors on transmission have been limited. Passive smoking, a great concern for children's health, has been reported to exacerbate pneumococcal diseases. Here, we describe the effect of cigarette smoke exposure on an infant mouse model of pneumococcal transmission. Our findings reveal that the effect of cigarette smoke exposure significantly promotes pneumococcal transmission by enhancing bacterial shedding from the colonized host and by increasing susceptibility to pneumococcal colonization in the new host, both of which are critical steps of transmission. Local inflammation, followed by mucosal changes (such as mucus hypersecretion and disruption of the mucosal barrier), are important underlying mechanisms for promotion of transmission by smoke exposure. These effects were attributable to the constituents of cigarette smoke rather than smoke itself. These findings provide the first experimental evidence of the impact of environmental factors on pneumococcal transmission and the mechanism of pathogenesis.

Acidic microenvironment induction of interleukin-8 expression and matrix metalloproteinase-2/-9 activation via acid-sensing ion channel 1 promotes breast cancer cell progression

The cancer microenvironment exhibits local acidosis compared with the surrounding normal tissue. Many reports have shown that acidosis accelerates the invasiveness and metastasis of cancer, yet the underlying molecular mechanisms remain unclear. In the present study, we focused on acid-induced functional changes through acid receptors in breast cancer cells. Acidic treatment induced interleukin (IL)-8 expression in MDA-MB-231 cells and promoted cell migration and invasion. The acidic microenvironment elevated matrix metalloproteinase (MMP)-2 and MMP-9 activity, and addition of IL-8 had similar effects. However, inhibition of IL-8 suppressed the acid-induced migration and invasion of MDA-MB-231 cells. MDA-MB-231 cells express various acid receptors including ion channels and G protein-coupled receptors. Interestingly, acidic stimulation increased the expression of acid-sensing ion channel 1 (ASIC1), and acid-induced IL-8 was significantly decreased by ASIC1 knockdown. Moreover, phosphorylation of nuclear factor (NF)-κB was induced by acidic treatment, and inhibition of NF-κB activation reduced acid-induced IL-8 expression. These results suggest that IL-8 induction by an acidic microenvironment promotes breast cancer development and that ASIC1 might be a novel therapeutic target for breast cancer metastasis.

The Gain-of-Function Mutation p53R248W Suppresses Cell Proliferation and Invasion of Oral Squamous Cell Carcinoma through the Down-Regulation of Keratin 17

Keratin 17 (KRT17) expression promotes the proliferation and invasion of oral squamous cell carcinoma (OSCC), and mutations in TP53 have been reported in 65% to 85% of OSCC cases. We studied the correlation between KRT17 expression and TP53 mutants. Ca9-22 cells, which exhibit low KRT17 expression, carried mutant p53 (p53R248W) and p53R248W knockdown promoted KRT17 expression. p53R248W knockdown in Ca9-22 cells promoted migration and invasion activity. In contrast, in HSC3 cells, which have p53 nonsense mutations and exhibit high KRT17 expression, the overexpression of p53R248W decreased KRT17 expression, cell size, proliferation, and migration and invasion activities. In addition, p53R248W significantly suppressed MMP2 mRNA expression and enzyme activity. Moreover, s.c. and orthotopic xenografts were generated from p53R248W- or p53R248Q-expressing HSC3 cells. Tumors formed from p53R248W-expressing HSC3 cells grew more slowly and had a lower Ki-67 index than those derived from the control or p53R248Q-expressing HSC3 cells. Finally, the survival rate of the mice inoculated with p53R248W-expressing HSC3 cells was significantly higher than that of the control mice. These results indicate that the p53R248W mutant suppresses proliferation and invasion activity through the suppression of KRT17 expression. We propose that OSCC with p53R248W-expressing cells may be classified as a new OSCC type that has a good prognosis.

Suppression of MKL1 promotes adipocytic differentiation and reduces the proliferation of myxoid liposarcoma cells

Myxoid liposarcoma (MLS) is thought to occur due to defective adipocytic differentiation in mesenchymal stem cells. A promising strategy for MLS treatment is the prevention of sarcomagenesis by promoting the terminal differentiation of MLS cells into adipocytes. Previous studies have reported that the suppression of megakaryoblastic leukemia 1 (MKL1) expression induces adipocytic differentiation in preadipocyte cell lines. The present study aimed to investigate the effects of MKL1 suppression on MLS cells. In the present study, MKL1 knockdown was demonstrated to promote the adipocytic differentiation of an MLS-derived cell line, designated 1955/91, under adipogenic conditions. This suggests that therapeutic targeting of the MKL1-associated molecular pathway has potential as a promising method of MLS treatment. However, the induction of adipogenesis by MKL knockdown was incomplete, and Oil Red O staining indicated that intracellular lipid droplets were only sporadically generated. Conversely, MKL1 knockdown reduced the growth of the MLS cells. As adipocytic differentiation in vitro requires cellular confluence, the decreased growth rate of the MLS cells following MKL1 knockdown could be attributed to the incomplete induction of adipogenesis. Translocated in liposarcoma-CCAAT/enhancer-binding protein homologous protein (TLS-CHOP) is an MLS-specific oncoprotein that is thought to play key roles in sarcomagenesis and the suppression of adipocytic differentiation. However, the results of western blotting analyses suggest that TLS-CHOP has limited effects on MKL1 expression in MLS cells and that MKL1 knockdown hardly affects TLS-CHOP expression. Thus, it is postulated that the inhibitory effect of TLS-CHOP on adipogenesis is not associated with MKL1 expression. However, MKL1 and the molecular pathway involving MKL1 appear to be attractive targets for the differentiation therapy of MLS.

MicroRNA 200b promotes mesenchymal-to-epithelial transition in anaplastic thyroid carcinoma

Anaplastic thyroid cancer (ATC) remains a cancer with one of the worst prognoses, despite novel targeted therapies. The median survival rate has not improved for decades. Epithelial-to-mesenchymal transition (EMT) is a crucial step in physiological processes and in cancer progression, but the underlying mechanisms are not yet fully understood. The current study examined the role of microRNA (miR)-200b in mesenchymal-to-epithelial transition in ATC. Total RNA and miR isolation were performed from ATC cell lines transfected with a miR-200b mimic. After miR-200b mimic transfection, expression levels of E-cadherin, vimentin and zinc finger E-box binding homeobox 1 (ZEB1) were confirmed by reverse transcription-quantitative PCR and western blotting. Additionally, cell migration was evaluated using miR-200b mimic and scrambled negative control-transfected cells. A total of 14 human ATC and 15 non-cancerous human thyroid tissues were immunohistochemically stained and scored as controls for E-cadherin, vimentin and ZEB1. In ATC tissues and cell lines, the mesenchymal marker ZEB1 was significantly upregulated and the epithelial marker E-cadherin was significantly downregulated. Additionally, the mesenchymal marker vimentin was significantly upregulated in ATC tissues and in one ATC cell line. MiR-200b mimic transfection significantly increased vimentin and ZEB1 expression, but E-cadherin expression remained below the measurement sensitivity. Furthermore, miR-200b overexpression decreased cell migration. The current study suggested that miR-200b may regulate the expression levels of mesenchymal markers such as vimentin and ZEB1 in ATC and may promote mesenchymal-to-epithelial transition.

Potential Role of DEC1 in Cervical Cancer Cells Involving Overexpression and Apoptosis

Basic helix-loop-helix (BHLH) transcription factors differentiated embryonic chondrocyte gene 1 (DEC1) and gene 2 (DEC2) regulate circadian rhythms, apoptosis, epithelial mesenchymal transition (EMT), invasions and metastases in various kinds of cancer. The stem cell markers SOX2 and c-MYC are involved in the regulation of apoptosis and poor prognosis. In cervical cancer, however, their roles are not well elucidated yet. To determine the function of these genes in human cervical cancer, we examined the expression of DEC1, DEC2, SOX2 and c-MYC in human cervical cancer tissues. In immunohistochemistry, they were strongly expressed in cancer cells compared with in non-cancerous cells. Notably, the strong rate of DEC1 and SOX2 expressions were over 80% among 20 cases. We further examined the roles of DEC1 and DEC2 in apoptosis. Human cervical cancer HeLa and SiHa cells were treated with cisplatin-HeLa cells were sensitive to apoptosis, but SiHa cells were resistant. DEC1 expression decreased in the cisplatin-treated HeLa cells, but had little effect on SiHa cells. Combination treatment of DEC1 overexpression and cisplatin inhibited apoptosis and affected SOX2 and c-MYC expressions in HeLa cells. Meanwhile, DEC2 overexpression had little effect on apoptosis and on SOX2 and c-MYC expressions. We conclude that DEC1 has anti-apoptotic effects and regulates SOX2 and c-MYC expressions on apoptosis.

PD-L1 expression correlated with p53 expression in oral squamous cell carcinoma

Background

Programmed cell death ligand 1 (PD-L1) is an immune checkpoint molecule that attenuates the immune response. PD-L1 contributes to failed antitumor immunity; thereby, blockade of PD-L1 with monoclonal antibody enhances the immune response. Recently, it was reported that PD-L1 was regulated by protein 53 (p53). Besides, cytokeratin 17 (CK17) is thought to be a diagnostic marker of oral squamous cell carcinoma (OSCC). Our aim was to evaluate the correlation between the immunohistochemical expression of PD-L1, p53 and CK17 with clinicopathological characteristics and disease-specific survival in patients with OSCC.

Methods

A total of 48 patients with OSCC were included in this study. Immunohistochemical staining was performed to evaluate the correlation among the expressions of PD-L1, p53 and CK17, and furthermore the correlation among various clinicopathological factors, PD-L1, p53 and CK17.

Results

The positive rate of p53, CK17, PD-L1 (tumor cells) and PD-L1 (tumor-infiltrating lymphocytes) was 63.2%, 91.7%, 48.9% and 57.1%. A statistically significant correlation between p53 expression and T stage and TNM stage (p = 0.049, p = 0.03, respectively) was observed. Also, a statistically significant correlation between p53 and PD-L1 (TCs) expression (p = 0.0009) was observed. Five-year disease-specific survival rate was not significantly correlated with gender, TNM stage, p53 expression, PD-L1 expression and CK17 expression.

Conclusion

The expression of p53 and PD-L1 shows significantly positive correlation in oral squamous cell carcinoma in tumor cells. Also, a significant correlation between p53 expression and T stage and TNM stage was observed. No other significant correlation between PD-L1 staining or CK17 and clinical or pathologic characteristics was identified.

Dec1 Deficiency Suppresses Cardiac Perivascular Fibrosis Induced by Transverse Aortic Constriction

Cardiac fibrosis is a major cause of cardiac dysfunction in hypertrophic hearts. Differentiated embryonic chondrocyte gene 1 (Dec1), a basic helix–loop–helix transcription factor, has circadian expression in the heart; however, its role in cardiac diseases remains unknown. Therefore, using Dec1 knock-out (Dec1KO) and wild-type (WT) mice, we evaluated cardiac function and morphology at one and four weeks after transverse aortic constriction (TAC) or sham surgery. We found that Dec1KO mice retained cardiac function until four weeks after TAC. Dec1KO mice also revealed more severely hypertrophic hearts than WT mice at four weeks after TAC, whereas no significant change was observed at one week. An increase in Dec1 expression was found in myocardial and stromal cells of TAC-treated WT mice. In addition, Dec1 circadian expression was disrupted in the heart of TAC-treated WT mice. Cardiac perivascular fibrosis was suppressed in TAC-treated Dec1KO mice, with positive immunostaining of S100 calcium binding protein A4 (S100A4), alpha smooth muscle actin (αSMA), transforming growth factor beta 1 (TGFβ1), phosphorylation of Smad family member 3 (pSmad3), tumor necrosis factor alpha (TNFα), and cyclin-interacting protein 1 (p21). Furthermore, Dec1 expression was increased in myocardial hypertrophy and myocardial infarction of autopsy cases. Taken together, our results indicate that Dec1 deficiency suppresses cardiac fibrosis, preserving cardiac function in hypertrophic hearts. We suggest that Dec1 could be a new therapeutic target in cardiac fibrosis.

P14.01 Differential diagnosis of IDH mutant/IDH wildtype of glioma by using 11C-methionine, 11C-choline, and18F-fluorodeoxyglucose positron emission tomography

BACKGROUND

Positron emission tomography (PET) is important in noninvasive diagnostic imaging of gliomas. There are many PET studies on glioma diagnosis based on the 2007 World Health Organization (WHO) classification; however, there are no studies on glioma diagnosis using the new classification (the 2016 WHO classification).Here we investigated the relationship between PET imaging using 11C-methionine (MET), 11C-choline (CHO), and 18F-fluorodeoxyglucose (FDG) and wildtype isocitrate dehydrogenase (IDH) (IDH-wt)/mutant IDH (IDH-mut) in astrocytic and oligodendroglial tumors according to the 2016 WHO classification.

MATERIAL AND METHODS

In total, 105 patients with newly diagnosed cerebral gliomas (six diffuse astrocytomas [DAs] with IDH-wt, six DAs with IDH-mut, seven anaplastic astrocytomas [AAs] with IDH-wt, 24 AAs with IDH-mut, 26 glioblastomas [GBMs] with IDH-wt, five GBMs with IDH-mut, 19 oligodendrogliomas [ODs], and 12 anaplastic oligodendrogliomas [AOs]) were included. All OD and AO patients had both IDH-mut and 1p/19q codeletion. The maximum standardized uptake values (SUVs) of the tumor/normal cortex mean SUV ratios (T/N ratios) for MET, CHO, and FDG were calculated; the mean T/N ratios of DA, AA, and GBM with IDH-wt/IDH-mut were compared. The diagnostic accuracy for distinguishing gliomas with IDH-wt from those with IDH-mut was assessed using receiver operating characteristic (ROC) curve analysis of the mean T/N ratios for the three PET tracers.

RESULTS

There were significant differences in the mean T/N ratios for all three PET tracers between the IDH-wt and IDH-mut groups including all histological classifications (p<0.001). Among the 27 gliomas with mean T/N ratios higher than the cutoff values for all three PET tracers, 23 (85.2%) were classified into the IDH-wt group using ROC analysis. In DA, there were no significant differences in the T/N ratios for MET, CHO, and FDG between the IDH-wt and IDH-mut groups. In AA, the mean T/N ratios of all three PET tracers in the IDH-wt group were significantly higher than those in the IDH-mut group (p<0.001). In GBM, the mean T/N ratio in the IDH-wt group was significantly higher than that of the IDH-mut group for both MET (p=0.034) and CHO (p=0.01). However, there was no significant difference in the ratio for FDG.

CONCLUSIONS

PET imaging using MET, CHO, and FDG was confirmed to be informative for preoperatively differentiating gliomas according to the 2016 WHO classification, particularly for differentiating IDH-wt and IDH-mut tumors.

Activation of KEAP1/NRF2/P62 signaling alleviates high phosphate-induced calcification of vascular smooth muscle cells by suppressing reactive oxygen species production

Vascular calcification is a complication of diseases and conditions such as chronic kidney disease, diabetes, and aging. Previous studies have demonstrated that high concentrations of inorganic phosphate (Pi) can induce oxidative stress and vascular smooth muscle cell calcification. KEAP1 (Kelch-like ECH-associated protein 1)/NF-E2-related factor 2 (NRF2) signaling has been shown to play important roles in protecting cells from oxidative stress. The current study aims to investigate the possible involvement of the KEAP1/NRF2/P62 -mediated antioxidant pathway in vascular calcification induced by high Pi levels. Exposure of vascular smooth muscle cells (VSMCs) to high Pi concentrations promoted the accumulation of reactive oxygen species (ROS) and the nuclear translocation of NRF2, along with an increase in P62 levels and a decrease in KEAP1 levels. A classic NRF2 activator, tert-butylhydroquinone (tBHQ), significantly decreased ROS levels and calcium deposition in VSMCs by promoting the nuclear translocation of NRF2 and upregulating P62 and KEAP1 expression. In contrast, silencing NRF2 and P62 with siRNAs increased the levels of ROS and calcium deposition in VSMCs. In conclusion, VSMC calcification can be alleviated by the activation of the KEAP1/NRF2/P62 antioxidative pathway, which could have a protective role when it is exogenously activated by tBHQ.

Abstract 3472: The role of mutant p53 R248W in oral squamous cell carcinoma

TP53 is the most commonly mutated gene in oral squamous cell carcinoma (OSCC). It is known that mutant p53 has not only loss of function but gain of function. Cytokeratin 17 (K17) has been shown to promote tumorigenesis and aggressiveness in OSCCs and other various carcinomas. Although p53 reportedly induces K17 transcription by irradiation, the molecular interaction between p53 and K17 in OSCCs remains unknown. To address this issue, we investigated the relationship between p53 and K17 using SAS cells with nonsense mutation and Ca9-22 cells with R248W mutation in the TP53 gene. Western blot and immunohistochemistry showed higher K17 expression in SAS cells and virtually no K17 expression in Ca9-22 cells, suggesting negative correlation between p53 and K17 expression. ChIP analysis revealed that p53 bound specifically to the tentative p53 binding site in the promoter region of the K17 gene. Unexpectedly, however, overexpression of wild-type (wt) p53 did not suppress K17 expression in SAS cells, whereas knock down of mutant (mt) p53 significantly upregulated K17 expression in Ca9-22 cells, raising a possibility that only R248W mtp53 suppresses K17 expression. Furthermore, overexpression of wtp53 and R248Q mtp53 did not suppressed K17 expression in Ca9-22 cells with knock down of p53, whereas R248W mtp53 overexpression clearly showed suppression of K17. Taken together, R248W mtp53 acts as a direct transcriptional repressor of K17 in OSCCs, reducing aggressiveness of the carcinoma cells.

Citation Format: Mayu Enaka, Masako Nakanishi, Yasuteru Muragaki. The role of mutant p53 R248W in oral squamous cell carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3472.

Differential expression of claudin‑4, occludin, SOX2 and proliferating cell nuclear antigen between basaloid squamous cell carcinoma and squamous cell carcinoma

Basaloid squamous cell carcinomas (BSCCs) in oral lesions are extremely rare, and the histology is not well understood. Histologically, they are often similar to conventional squamous cell carcinoma (SCC). The present study was designed with an aim to distinguish BSCC from SCC using claudin‑4, occludin, SRY‑box 2 (SOX2) and proliferating cell nuclear antigen (PCNA) immunoreactivities and staining patterns. Three BSCCs (with abundant, with moderate, and without squamous components) specimens and 20 SCC specimens were selected for comparison of their immunoreactivity. These specimens were stained with claudin‑4, occludin, SOX2 and PCNA. In addition to histological analysis, the expression of claudin‑4, occludin and PCNA was determined in oral cancer HSC2 and HSC3 cells with or without SOX2 overexpression, and cell proliferation was determined by XTT assay. Claudin‑4 had strong and occludin had weak immunoreactivity as detected in the membrane of squamous components of BSCC but not in cancer cells. No obvious detection of squamous components and cancer cells were observed in SCC. SOX2 and PCNA immunoreactivities in SCC had dot‑like staining patterns in the nuclei of partial and marginal cancer cells. In contrast, in BSCCs, SOX2 and PCNA had diffuse staining patterns in almost all cancer cells. SOX2 overexpression had little effect on the expression levels of claudin‑4, occludin and PCNA. It also had little effect on the cell proliferation of HSC2 and HSC3 cells. Differences in immunoreactivity and staining pattern may be valuable to distinguish between BSCC and SCC in diagnosis.

Trps1-deficient transplanted skin gave rise to a substantial amount of hair: Trps1 is unnecessary for hair development

Trps1 is considered as an important gene involved in the interactions between the epithelial and mesenchymal cells during hair follicle morphogenesis. The number of hair follicles in Trps1 Knockout (KO) newborn mouse skin was significantly lower than that in wild-type (WT) newborn skin. To gain insight into the functional role of Trps1 in hair development, we transplanted Trps1 KO newborn mouse skin on the backs of nude mice and examined hair growth at day 42 after transplantation. Surprisingly, transplanted skin from Trps1 KO newborn mice gave rise to a substantial amount of hair, although the hair was softer than that of WT mice. Histological examination revealed that the diameter of both hair follicles and hair shafts were significantly lower, whereas the density of hair follicles showed no significant difference between the Trps1 KO and WT mice. We introduce mouse hair follicles as a fascinating model to study the functions of Trps1 in mouse hair growth and pathology. This model suggests that the function of Trps1 is unnecessary for the development of normal hair follicles and hair shafts, although the loss of Trps1 affects the diameters of hair follicles and hair shaft.

Smad3 Suppresses Epithelial Cell Migration and Proliferation via the Clock Gene Dec1, Which Negatively Regulates the Expression of Clock Genes Dec2 and Per1

Smad3 has circadian expression; however, whether Smad3 affects the expression of clock genes is poorly understood. Here, we investigated the regulatory mechanisms between Smad3 and the clock genes Dec1, Dec2, and Per1. In Smad3 knockout mice, the amplitude of locomotor activity was decreased, and Dec1 expression was decreased in the suprachiasmatic nucleus, liver, kidney, and tongue compared with control mice. Conversely, Dec2 and Per1 expression was increased compared with that of control mice. In Smad3 knockout mice, immunohistochemical staining revealed that Dec1 expression decreased, whereas Dec2 and Per1 expression increased in the endothelial cells of the kidney and liver. In NIH3T3 cells, Smad3 overexpression increased Dec1 expression, but decreased Dec2 and Per1 expression. In a wound-healing experiment that used Smad3 knockout mice, Dec1 expression decreased in the basal cells of squamous epithelium, promoting wound healing of the mucosa. Finally, the migration and proliferation of Smad3 knockdown squamous carcinoma cells was suppressed by Dec1 overexpression but was promoted by Dec2 overexpression. Dec1 overexpression decreased E-cadherin and proliferating cell nuclear antigen expression, whereas these expression levels were increased by Dec2 overexpression. These results suggest Smad3 is relevant to circadian rhythm and regulates cell migration and proliferation through Dec1, Dec2, and Per1 expression.

Abstract 1409: p53 negatively regulates keratin 17 expression in oral squamous cell carcinoma

Background: Cytokeratin 17 (K17) has been shown to promote tumorigenesis and aggressiveness in oral squamous cell carcinomas (OSCCs) and other various carcinomas. Although p53 reportedly induces K17 transcription by irradiation, the correlation between p53 and K17 in OSCCs remains unknown. Methods: Human OSCC cell lines SAS and Ca9-22 were examined by Western blot, immunohistochemistry, ChIP assays, and overexpression of wild-type p53. Biopsy specimens from patients with OSCC were used for immunohistochemistry.Results: Western blot and immunohistochemistry showed that K17 expression negatively correlated with p53 expression. In biopsy specimens, positive staining for K17 was observed in OSCC cells that were negative for p53 in a mutually exclusive manner. SAS cells, which have higher K17 expression and almost negative p53 expression, showed more aggressive characteristics than Ca9-22 cells. A mutation to cause a premature stop codon was identified in the TP53 gene in SAS cells by DNA sequencing, whereas no mutation in the TP53 gene was identified in Ca9-22 cells. In addition, ChIP analysis showed that p53 bound specifically to the promoter region of the K17 gene. Furthermore, overexpression of wild-type p53 suppressed K17 expression in SAS cells. Conclusion: p53 acts as a direct transcriptional repressor of K17 in OSCCs. The interaction between p53 and K17 may regulate aggressiveness of the carcinoma cells.

Citation Format: Mayu Enaka, Masako Nakanishi, Yasuteru Muragaki. p53 negatively regulates keratin 17 expression in oral squamous cell carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1409.

Impact of heart-specific disruption of the circadian clock on systemic glucose metabolism in mice

The daily rhythm of glucose metabolism is governed by the circadian clock, which consists of cell-autonomous clock machineries residing in nearly every tissue in the body. Disruption of these clock machineries either environmentally or genetically induces the dysregulation of glucose metabolism. Although the roles of clock machineries in the regulation of glucose metabolism have been uncovered in major metabolic tissues, such as the pancreas, liver, and skeletal muscle, it remains unknown whether clock function in non-major metabolic tissues also affects systemic glucose metabolism. Here, we tested the hypothesis that disruption of the clock machinery in the heart might also affect systemic glucose metabolism, because heart function is known to be associated with glucose tolerance. We examined glucose and insulin tolerance as well as heart phenotypes in mice with heart-specific deletion of Bmal1, a core clock gene. Bmal1 deletion in the heart not only decreased heart function but also led to systemic insulin resistance. Moreover, hyperglycemia was induced with age. Furthermore, heart-specific Bmal1-deficient mice exhibited decreased insulin-induced phosphorylation of Akt in the liver, thus indicating that Bmal1 deletion in the heart causes hepatic insulin resistance. Our findings revealed an unexpected effect of the function of clock machinery in a non-major metabolic tissue, the heart, on systemic glucose metabolism in mammals.

Smad3 and Bmal1 regulate p21 and S100A4 expression in myocardial stromal fibroblasts via TNF-α

Bmal1, a clock gene, is associated with depression, hypertrophy, metabolic syndrome and diabetes. Smad3, which is involved in the TGF-β signaling pathway, plays an important role in the regulation of tumor progression, fibrosis, obesity and diabetes. Our previous report showed that Smad3 has circadian expression in mouse livers. In the current study, we focused on the heart, especially on the myocardial stromal fibroblasts because the roles of Bmal1 and Smad3 in this tissue are poorly understood. Bmal1 and Smad3 have circadian expression in mouse hearts, and their circadian expression patterns were similar. Bmal1 expression decreased in the hearts of whole-body Smad3 knockout mice, whereas Smad3 expression had little effect on heart-specific Bmal1 knockout mice. Both Smad3 knockout and heart-specific Bmal1 knockout mice showed increases in p21, S100A4, CD206 and TNF-α expression in the myocardial stromal fibroblasts and macrophage compared to control mice. We also examined Smad3, Bmal1 and Dec1 expression in human tissue from old myocardial infarctions. Expression of Smad3, Bmal1 and Dec1 decreased in the stromal fibroblasts of tissue from old myocardial infarctions compared to control cases. On the other hand, p21, S100A4 and TNF-α increased in the stromal fibroblasts of tissue from old myocardial infarctions. Furthermore, expression of Smad3, Bmal1 and Dec1 decreased in TNF-α treated-NIH3T3 cells but expression of p21 and S100A4 increased. This new evidence suggests that Smad3 and Bmal1 regulate p21 and S100A4 expression in myocardial stromal fibroblasts through TNF-α.

Abstract 2026: DEC1 negatively regulates AMPK activity via LKB1

Basic helix-loop-helix (bHLH) transcription factor DEC1 (bHLHE40/Stra13/Sharp2) is one of the clock genes that show a circadian rhythm in various tissues. AMP-activated protein kinase (AMPK) activity plays important roles in metabolism and in cell death induced by glucose depletion. Recent reports have shown that AMPK activity exhibited a circadian rhythm. However, how the circadian rhythm of AMPK activity is regulated is not known. The aim of this study is the direct correlation between DEC1 expression and AMPK activity. DEC1 protein and AMPK activity showed a circadian rhythm in the mouse liver with different peak levels. A medium change and serum shock led to rhythmic patterns of DEC1 protein and AMPK activity levels in WI-38 cells, and their peak levels occurred at different times. However, changing the medium did not induce circadian rhythms of DEC1 protein or AMPK activity levels in MCF-7 and U2OS cells, in which the intensities of these levels had inversely correlated patterns. Knocking down DEC1 expression increased AMPK activity, whereas DEC1 overexpression decreased it. DEC1 bound to the E-box of the LKB1 promoter, decreasing the LKB1 activity and total protein levels. In addition, knocking down DEC1 expression inhibited cell death under the condition of glucose depletion, increasing the activity of both AMPK and LKB1. Taken together, our results showed that the levels of DEC1 protein and AMPK activity were affected even long after the medium change and that the rhythmic patterns of these levels were inversely correlated. We concluded that DEC1 negatively regulated AMPK activity via LKB1.

Citation Format: Fuyuki Sato, Yasuteru Muragaki. DEC1 negatively regulates AMPK activity via LKB1. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2026.

Refractory Ascites with Liver Fibrosis Developed in Late Phase Allogeneic Hematopoietic Stem Cell Transplantation: Report of Three Patients

We report cases of three patients of refractory ascites without other fluid retention that occurred around five months after allogeneic hematopoietic stem cell transplantation (allo-HSCT). All three patients expired and postmortem examinations revealed unexpected liver fibrosis lacking histological evidences of graft-versus-host-disease (GVHD). The three patients showed normal hepatic function and size before transplantation. During their clinical courses, serum biochemistry test showed no elevation of hepatic enzymes and bilirubin; however, imaging studies demonstrated hepatic atrophy at the onset of ascites. One of the liver specimens showed bile obstruction, which could be seen in hepatic damage by GVHD. Although ascites resulting from venoocclusive disease in early phase allo-HSCT is well documented, ascites associated with hepatic fibrosis in late phase allo-HCST has not been reported. Further clinico-pathological studies on similar patients should be required to ascertain refractory ascites associated with liver fibrosis after allo-HSCT.

Rhythmic expression of DEC2 protein in vitro and in vivo

Basic helix-loop-helix (bHLH) transcription factor DEC2 (bHLHE41/Sharp1) is one of the clock genes that show a circadian rhythm in various tissues. DEC2 regulates differentiation, sleep length, tumor cell invasion and apoptosis. Although studies have been conducted on the rhythmic expression of DEC2 mRNA in various tissues, the precise molecular mechanism of DEC2 expression is poorly understood. In the present study, we examined whether DEC2 protein had a rhythmic expression. Western blot analysis for DEC2 protein revealed a rhythmic expression in mouse liver, lung and muscle and in MCF-7 and U2OS cells. In addition, AMP-activated protein kinase (AMPK) activity (phosphorylation of AMPK) in mouse embryonic fibroblasts (MEFs) exhibited a rhythmic expression under the condition of medium change or glucose-depleted medium. However, the rhythmic expression of DEC2 in MEF gradually decreased in time under these conditions. The medium change affected the levels of DEC2 protein and phosphorylation of AMPK. In addition, the levels of DEC2 protein showed a rhythmic expression in vivo and in MCF-7 and U2OS cells. The results showed that the phosphorylation of AMPK immunoreactivity was strongly detected in the liver and lung of DEC2 knockout mice compared with that of wild-type mice. These results may provide new insights into rhythmic expression and the regulation between DEC2 protein and AMPK activity.

DEC1 and DEC2 Crosstalk between Circadian Rhythm and Tumor Progression

Clock genes, major regulators of circadian rhythm, are involved in tumor progression. We have shown that clock genes basic helix-loop-helix (BHLH) transcription factors, differentiated embryonic chondrocyte gene 1 (DEC1/BHLHE40/Sharp2/Stra13) and DEC2 (BHLHE41/Sharp1) play important roles in circadian rhythm, cell proliferation, apoptosis, hypoxia response, various stresses, and epithelial-to-mesenchymal transition (EMT) of tumor cells. Various stresses, such as exposure to transforming growth factor-beta (TGF-β), hypoxia, cytokines, serum-free, and anti-tumor drugs affect DEC1 and DEC2 expression. An increased or decreased expression of DEC1 and DEC2 regulated tumor progression. However, DEC1 and DEC2 have opposite effects in tumor progression, where the reason behind remains unclear. We found that DEC2 has circadian expression in implanted mouse sarcoma cells, suggesting that DEC2 regulates tumor progression under circadian rhythm. In addition to that, we showed that DEC1 and DEC2 regulate target genes via positive or negative feedback system in tumor progression. We propose that DEC1 and DEC2 act as an accelerator or a brake in tumor progression. In this review, we summarize current progress of knowledge in the function of DEC1 and DEC2 genes in tumor progression.

DEC1 negatively regulates AMPK activity via LKB1

Basic helix-loop-helix (bHLH) transcription factor DEC1 (bHLHE40/Stra13/Sharp2) is one of the clock genes that show a circadian rhythm in various tissues. AMP-activated protein kinase (AMPK) activity plays important roles in the metabolic process and in cell death induced by glucose depletion. Recent reports have shown that AMPK activity exhibited a circadian rhythm. However, little is known regarding the regulatory mechanisms involved in the circadian rhythm of AMPK activity. The aim of this study is to investigate whether there is a direct correlation between DEC1 expression and AMPK activity. DEC1 protein and AMPK activity showed a circadian rhythm in the mouse liver with different peak levels. Knocking down DEC1 expression increased AMPK activity, whereas overexpression of DEC1 decreased it. Overexpressing the DEC1 basic mutants had little effect on the AMPK activity. DEC1 bound to the E-box of the LKB1 promoter, decreased LKB1 activity and total protein levels. There was an inverse relationship between DEC1 expression and AMPK activity. Our results suggest that DEC1 negatively regulates AMPK activity via LKB1.

B-Cell-Rich T-Cell Lymphoma Associated with Epstein-Barr Virus-Reactivation and T-Cell Suppression Following Antithymocyte Globulin Therapy in a Patient with Severe Aplastic Anemia

B-cell lymphoproliferative disorder (B-LPD) is generally characterized by the proliferation of Epstein-Barr virus (EBV)-infected B lymphocytes. We here report the development of EBV-negative B-LPD associated with EBV-reactivation following antithymocyte globulin (ATG) therapy in a patient with aplastic anemia. The molecular autopsy study showed the sparse EBV-infected clonal T cells could be critically involved in the pathogenesis of EBV-negative oligoclonal B-LPD through cytokine amplification and escape from T-cell surveillances attributable to ATG-based immunosuppressive therapy, leading to an extremely rare B-cell-rich T-cell lymphoma. This report helps in elucidating the complex pathophysiology of intractable B-LPD refractory to rituximab.

Abstract 2999: DEC1 and DEC2 crosstalk between circadian rhythm and tumor progression

Circadian rhythms are tightly regulated by clock genes. It has been reported that clock genes plays important roles in biological function of normal cells. However, it is not well understood the function of clock genes in tumor cells. We showed that basic helix-loop-helix (bHLH) transcription factors, differentiated embryonic chondrocyte gene 1 (DEC1/BHLHE40/Sharp2/Stra13) and DEC2 (BHLHE41/Sharp1), are clock genes and play important roles in circadian rhythm, cell proliferation, apoptosis, hypoxia response, various stresses and epithelial-to-mesenchymal transition (EMT) in tumor cells. Various stresses, such as exposure to transforming growth factor-beta (TGF-β), hypoxia, cytokines, serum-free, and anti-tumor drugs affect DEC expression. The increased or decreased DEC expression by such stresses is involved in tumor progression. The evidence that DEC2 has circadian expression in implanted mouse sarcoma cells and negatively regulates VEGF expression under hypoxia. DEC1 has pro-apoptotic effects in human breast cancer cells, whereas DEC2 has anti-apoptotic effects. DEC1 induced EMT by TGF-β in human pancreatic cancer cells, whereas DEC2 suppressed EMT. Immunohistochemical analysis showed that DEC1 is highly expressed in tumor cells and the expression is involved in malignancy. On the other hand, DEC2 is little expressed in tumor cells compared with adjacent non-tumor cells. These findings suggest that DEC1 and DEC2 have different roles in tumor progression under circadian rhythm. DEC2 regulates the circadian rhythm and VEGF expression by negative feed-back system, and DEC1 and DEC2 regulates EMT by positive and negative feed-back system in tumor cells. So, DEC acts as “accelerator” and “brake” in tumor progression. In this study, we show current progress of the DEC genes in tumor progression.

Citation Format: Fuyuki Sato, Yasuteru Muragaki. DEC1 and DEC2 crosstalk between circadian rhythm and tumor progression. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2999. doi:10.1158/1538-7445.AM2015-2999

Trps1 deficiency inhibits the morphogenesis of secondary hair follicles via decreased Noggin expression

A representative phenotype of patients with tricho-rhino-phalangeal syndrome (TRPS) is sparse hair. To understand the developmental defects of these patient's hair follicles, we analyzed the development of hair follicles histologically and biochemically using Trps1 deficient (KO) mice. First, we compared the numbers of primary hair follicles in wild-type (WT) and KO embryos at different developmental stages. No differences were observed in the E14.5 skins of WT and KO mice. However, at later time points, KO fetal skin failed to properly develop secondary hair follicles, and the number of secondary hair follicles present in E18.5 KO skin was approximately half compared to that of WT skin. Sonic hedgehog expression was significantly decreased in E17.5 KO skin, whereas no changes were observed in Eda/Edar expression in E14.5 or E17.5 skins. In addition, Noggin expression was significantly decreased in E14.5 and E17.5 KO skin compared to WT skin. In parallel with the suppression of Noggin expression, BMP signaling was promoted in the epidermal cells of KO skins compared to WT skins as determined by immunohistochemistry for phosphorylated Smad1/5/8. The reduced number of secondary hair follicles was restored in skin graft cultures treated with a Noggin and BMP inhibitor. Furthermore, decreased cell proliferation, and increased apoptosis in KO skin was rescued by Noggin treatment. Taken together, we conclude that hair follicle development in Trps1 KO embryos is impaired directly or indirectly by decreased Noggin expression.

Elevated serum 1,25(OH)2-vitamin D3 level attenuates renal tubulointerstitial fibrosis induced by unilateral ureteral obstruction in kl/kl mice

Previous studies have suggested that Klotho provides reno-protection against unilateral ureteral obstruction (UUO)-induced renal tubulointerstitial fibrosis (RTF). Because the existing studies are mainly performed using heterozygous Klotho mutant (HT) mice, we focused on the effect of UUO on homozygous Klotho mutant (kl/kl) mice. UUO kidneys from HT mice showed a significantly higher level of RTF and TGF-β/Smad3 signaling than wild-type (WT) mice, whereas both were greatly suppressed in kl/kl mice. Primary proximal tubular epithelial culture cells isolated from kl/kl mice showed no suppression in TGF-β1-induced epithelial mesenchymal transition (EMT) compared to those from HT mice. In the renal epithelial cell line NRK52E, a large amount of inorganic phosphate (Pi), FGF23, or calcitriol was added to the medium to mimic the in vivo homeostasis of kl/kl mice. Neither Pi nor FGF23 antagonized TGF-β1-induced EMT. In contrast, calcitriol ameliorated TGF-β1-induced EMT in a dose dependent manner. A vitamin D₃-deficient diet normalized the serum 1,25 (OH)₂ vitamin D₃ level in kl/kl mice and enhanced UUO-induced RTF and TGF-β/Smad3 signaling. In conclusion, the alleviation of UUO-induced RTF in kl/kl mice was due to the TGF-β1 signaling suppression caused by an elevated serum 1, 25(OH)₂ vitamin D₃.

Cell culture of human gingival fibroblasts, oral cancer cells and mesothelioma cells with serum-free media, STK1 and STK2

The majority of cells are cultured with Dulbecco's modified Eagle's medium (DMEM) or RPMI supplemented with fetal bovine serum (FBS), which contains numerous factors, including cytokines, nutrients and unknown growth factors. These factors may affect cell growth, apoptosis and differentiation. The serum-free medium, STK2, has been previously reported as suitable for the cell culture of human mesenchymal stem cells. However, how STK1 or STK2 affect the cell proliferation of normal and cancer cells remains unknown. The present study examined the growth of the human gingival fibroblast (HGF-1) cell-line and the HSC-3, CA9-22 and MSTO cancer cell-lines, cultured with STK1 and STK2. STK1 increased the cell proliferation of HGF-1 compared to DMEM by assessment with the 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)- 2H-tetrazolium (MTS) assay, whereas STK1 and STK2 markedly inhibited the cell proliferation of HSC-3 and MSTO. The cell proliferation rate of CA9-22 cultured with STK1 or STK2 for 96 h was ~2-fold higher than the rate for 24 h culture. The shape of the HSC-3 cells was also found to have changed to round when cultured with STK2. These results indicate that STK1 increased the cell proliferation of HGF-1 compared to DMEM, whereas the proliferation of HSC-3 and MSTO was inhibited by STK1 and STK2. Thus, STK1 and STK2 had different affects on the cell growth of HGF-1, CA9-22, HSC-3 and MSTO.