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Introduction: In this multicenter clinical study, we aimed to investigate the efficacy and safety of the transhepatic arterial administration of granulocyte-colony stimulating factor (G–CSF)–mobilized autologous peripheral blood (PB)-CD34+ cells compared with standard therapy in patients with decompensated cirrhosis type C. Methods: Patients were randomly assigned (2:1) to the CD34+ cell transplant (CD34+ cell) or standard-of-care (SOC) group and followed up for 52 weeks. The primary endpoints were the non-progression rate of Child-Pugh (CP) scores at 24 weeks post-enrollment and the safety of the protocol treatment. Results: Fourteen patients (CD34+ cell group: 10; SOC group: 4) were enrolled. CP scores at 24 weeks had a non-progression rate of 90% in the CD34+ cell group and 100% in the SOC group, with no significant difference between groups. Importantly, 4 out of 10 patients in the CD34+ cell group exhibited an improvement from decompensated to compensated cirrhosis, whereas all patients in the SOC group remained in decompensated cirrhosis. With regard to secondary endpoints, a trend toward increased serum albumin levels in the CD34+ cell group was noted. Serious adverse events (SAEs) occurred in three patients in the CD34+ cell group and in one patient in the SOC group. No causal relationship was observed between all SAEs and G-CSF, leukapheresis, or cell transplantation in the CD34+ cell group. No patients died and no hepatocellular carcinoma occurred within the study period. Conclusions: PB-CD34+ cell infusion therapy may have the potential to circumvent the decompensated stage of cirrhosis, thus avoiding the need for liver transplantation.

Abstract Normal epithelial cells exert their competitive advantage over RasV12-transformed cells and eliminate them into the apical lumen via cell competition. However, the internal or external factors that compromise cell competition and provoke carcinogenesis remain elusive. In this study, we examine the effect of sequential accumulation of gene mutations, mimicking multi-sequential carcinogenesis on RasV12-induced cell competition in intestinal epithelial tissues. Consequently, we find that the directionality of RasV12-cell extrusion in Wnt-activated epithelia is reversed, and transformed cells are delaminated into the basal lamina via non-cell autonomous MMP21 upregulation. Subsequently, diffusively infiltrating, transformed cells develop into highly invasive carcinomas. The elevated production of MMP21 is elicited partly through NF-κB signaling, blockage of which restores apical elimination of RasV12 cells. We further demonstrate that the NF-κB-MMP21 axis is significantly bolstered in early colorectal carcinoma in humans. Collectively, this study shows that cells with high mutational burdens exploit cell competition for their benefit by behaving as unfit cells, endowing them with an invasion advantage.

Abstract Background We previously demonstrated that CD34 + cell transplantation in animals healed intractable fractures via osteogenesis and vasculogenesis; we also demonstrated the safety and efficacy of this cell therapy in an earlier phase I/II clinical trial conducted on seven patients with fracture nonunion. Herein, we present the results of a phase III clinical trial conducted to confirm the results of the previous phase studies using a larger cohort of patients. Methods CD34 + cells were mobilized via administration of granulocyte colony-stimulating factor, harvested using leukapheresis, and isolated using magnetic cell sorting. Autologous CD34 + cells were transplanted in 15 patients with tibia nonunion and 10 patients with femur nonunion, who were followed up for 52 weeks post transplantation. The main outcome was a reduction in time to heal the tibia in nonunion patients compared with that in historical control patients. We calculated the required number of patients as 15 based on the results of the phase I/II study. An independent data monitoring committee performed the radiographic assessments. Adverse events and medical device failures were recorded. Results All fractures healed during the study period. The time to radiological fracture healing was 2.8 times shorter in patients with CD34 + cell transplantation than in the historical control group (hazard ratio: 2.81 and 95% confidence interval 1.16–6.85); moreover, no safety concerns were observed. Conclusions Our findings strongly suggest that autologous CD34 + cell transplantation is a novel treatment option for fracture nonunion. Trial registration UMIN-CTR, UMIN000022814. Registered on 22 June 2016.

Ras mutations induce cell competition and cellular senescence to inhibit the proliferation of oncogenic mutated cells. Here the authors demonstrate that cellular senescence inhibits cell competition-induced elimination of oncogenic cells through HGF signalling.

Abstract Objectives Epidermolysis bullosa (EB) is a hereditary disorder characterized by mechanical stress‐induced blistering. The presence of extracutaneous complications such as cardiomyopathy and renal disease observed in severe EB subtypes and the fact that pruritus is a common symptom across all EB subtypes indicate that EB is not only a skin fragility disease but also a systemic inflammatory disorder. Our study aims to elucidate the basis of the systemic inflammation seen in EB patients. Methods We analyzed serum samples of 20 EB patients by Luminex bead‐based cytokine assays and enzyme‐linked immunosorbent assays. Results The serum levels of sIL‐2R, IL‐6, HGF, M‐CSF, SCGF‐β, IL‐8, IL‐16, IFN‐γ, MIF, MIP‐1α, and thymic stromal lymphopoietin (TSLP) (p

Abstract Fetal growth restriction (FGR) and pre-eclampsia with fetal growth restriction (PE/FGR) are high-risk perinatal diseases that may involve high levels of human chorionic gonadotropin (hCG) and mitochondrial dysfunction. However, little is known about how these factors affect placental function. We investigated how mitochondrial dysfunction and high hCG expression affected placental function in unexplained FGR and PE/FGR. We observed elevated expression of hCGβ and growth differentiation factor 15 mRNA and protein levels in the placenta with both diseases. Likewise, antiangiogenic factors, such as Ang2, IP10, sFlt1, IL8, IL1B, and TNFα, were also upregulated at the mRNA level. In addition, the expression of COXI and COXII which encoded by mitochondrial DNA were significantly decreased in both diseases, suggesting that mitochondrial translation was impaired. Treatment with hCG increased Ang2, IP10, IL8, and TNFα mRNA levels in a dose-dependent manner via the p38 and JNK pathways. Mitochondrial translation inhibitors increased hCGβ expression through stabilization of HIF1α, and increased IL8 and TNFα mRNA expression. These results revealed that high expression of hCG due to mitochondrial translational dysfunction plays an important role in the pathogenesis of FGR and PE/FGR.

Changes in cell mechanics contribute to cancer cell dissemination. Here the authors show that high plasma membrane (PM) tension inhibits cancer dissemination by counteracting mechanosensitive BAR family protein assembly, while restoration of PM tension phenotypically convert malignant cells into a non-motile epithelial cell state.

Objective: We sought to investigate the efficacy of human bone marrow mesenchymal stem/stromal cell (hBM-MSC) in a murine spinal cord ischemia/reperfusion (SCIR) model. Methods: C57BL/6J mice were subjected to SCIR by crossclamping the aortic arch and left subclavian artery for 5.5 minutes. Two hours after reperfusion, hBM-MSCs (hBM-MSC group) or phosphate-buffered saline (control group) were intravenously injected without immunosuppressant. Hindlimb motor function was assessed until day 28 after reperfusion using the Basso Mouse Scale (BMS). The lumbar spinal cord was harvested at hour 24 and day 28, and the histologic number of NeuN-positive motor neurons in 3 cross-sections of each lumbar spinal cord and the gene expression were evaluated. Results: BMS score was 0 throughout the study period in all control mice. BMS score was significantly greater in the hBM-MSC group than the control group from hour 8 (P

Abstract Introduction Our previous clinical studies have demonstrated the short-term efficacy and safety of the sirolimus gel for patients with tuberous sclerosis complex (TSC). However, long-term clinical evidence is lacking. Our objective was to assess the safety and efficacy of long-term treatment with the sirolimus gel for the skin lesions of TSC patients. Methods We conducted a multicenter, open-label, uncontrolled clinical trial in 94 Japanese patients with TSC. Patients applied the 0.2% sirolimus gel on their face or head twice daily for > 52 weeks (maximum 136 weeks for safety). The safety endpoints were the rate of adverse event (AE)-caused discontinuation (primary endpoint) and the incidence of AEs. The efficacy endpoint was the response rate of angiofibromas, cephalic plaques, and hypomelanotic macules. Results Among 94 enrolled patients (mean age, 21 years; range 3–53 years), the rate of AE-caused discontinuation was 2.1% (2/94 patients). Although application site irritation and dry skin occurred relatively frequently, none of the drug-related AEs were serious; most of the drug-related AEs resolved rapidly. The major drug-related AEs (≥ 5% in incidence) were application site irritation (30.9%), dry skin (27.7%), acne (20.2%), eye irritation (8.5%), pruritus (8.5%), erythema (7.4%), dermatitis acneiform (6.4%), and dermatitis contact (5.3%). The response rates of angiofibromas, cephalic plaques, and hypomelanotic macules were 78.2% [95% confidence interval (CI) 68.0–86.3%], 66.7% (95% CI 51.1–80.0%), and 72.2% (95% CI 46.5–90.3%), respectively. Conclusions The gel was well tolerated for a long time by patients with TSC involving facial skin lesions and continued to be effective. Trial Registration ClinicalTrials.gov identifier: NCT02634931.

Summary: At the initial stage of carcinogenesis, cell competition often occurs between newly emerging transformed cells and the neighboring normal cells, leading to the elimination of transformed cells from the epithelial layer. For instance, when RasV12-transformed cells are surrounded by normal cells, RasV12 cells are apically extruded from the epithelium. However, the underlying mechanisms of this tumor-suppressive process still remain enigmatic. We first show by electron microscopic analysis that characteristic finger-like membrane protrusions are projected from both normal and RasV12 cells at their interface. In addition, FBP17, a member of the F-BAR proteins, accumulates in RasV12 cells, as well as surrounding normal cells, which plays a positive role in the formation of finger-like protrusions and apical elimination of RasV12 cells. Furthermore, cdc42 acts upstream of these processes. These results suggest that the cdc42/FBP17 pathway is a crucial trigger of cell competition, inducing “protrusion to protrusion response” between normal and RasV12-transformed cells.

Nail-patella syndrome is an autosomal dominant disorder characterized by nail dysplasia and skeletal anomaly. Some patients have been shown to have ultrastructural abnormalities of the glomerular basement membrane that result in nephrosis. However, little has been reported on the epidermal basement membrane in this condition. This paper reports 2 families with nail-patella syndrome. Direct sequencing analysis of LMX1B revealed that family 1 and family 2 were heterozygous for the mutations c.140-1G>C and c.326+1G>C, respectively. To evaluate the epidermal basement membrane zone, ultrastructural and immunohistochemical analyses were performed using skin specimens obtained from the dorsal thumb. Electron microscopy showed intact hemidesmosomes, lamina lucida, lamina densa, and anchoring fibrils. Immunofluorescence studies with antibodies against components of the epidermal basement membrane zone revealed a normal expression pattern among the components, including type IV collagen. These data suggest that nail dysplasia in patients with nail-patella syndrome is not caused by structural abnormalities of the epidermal basement membrane.

Gastric cancer involving the placenta during pregnancy is rare; however, we present 1 such case in this report. A 31-year-old Japanese woman was referred at 26 weeks of gestation for the evaluation of a swollen left supraclavicular lymph node. Biopsy revealed poorly differentiated adenocarcinoma, and esophagogastroduodenoscopy with biopsy of the stomach confirmed the diagnosis of gastric cancer. Her epigastric and back pain became more pronounced and her general status worsened, and we performed a cesarean delivery at 29 weeks. Microscopic examination of the placental specimen revealed poorly differentiated adenocarcinoma cells diffused into the intervillous space. Postpartum chemotherapy consisted of S-1 plus oxaliplatin. Unfortunately, this treatment was ineffective, and the patient died 3 months after delivery. The infant did well, without clinical or laboratory manifestations of metastasis. In patients with advanced gastric cancer during pregnancy, it is important to perform a microscopic examination of the placenta to evaluate for metastatic involvement.

Primary bronchial tumors are extremely rare. However, symptoms, such as coughing and wheezing, are not specific to this disease, and primary bronchial tumors are often misdiagnosed as bronchial asthma. This report describes the case of a pregnant patient with a bronchial tumor that mimicked deteriorating bronchial asthma. A 37-year-old female patient suffered from repeated episodes of pneumonia since 26 weeks of gestation. Despite treatment, she suffered from another episode of pneumonia at 28 weeks of gestation. This was considered as deteriorating asthma. Bronchoscopy performed at 34 weeks of gestation showed a tumor in the left main lung bronchus, obstructing nearly 100% of the trachea. After cesarean delivery at 34 weeks, she underwent endoscopic bronchial tumor resection. Because of recurrent bronchial obstruction and the possibility of malignant disease, subsequent left main lung bronchial resection and bronchoplasty were performed. The pathological diagnosis was low-grade mucoepidermoid carcinoma. In conclusion, if pneumonia develops repeatedly during pregnancy, the possibility of bronchial tumor should be considered.

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Summary: Previous studies have revealed that, at the initial step of carcinogenesis, transformed cells are often eliminated from epithelia via cell competition with the surrounding normal cells. In this study, we performed cell competition-based high-throughput screening for chemical compounds using cultured epithelial cells and confocal microscopy. PLX4720 was identified as a hit compound that promoted apical extrusion of RasV12-transformed cells surrounded by normal epithelial cells. Knockdown/knockout of ZAK, a target of PLX4720, substantially enhanced the apical elimination of RasV12 cells in vitro and in vivo. ZAK negatively modulated the accumulation or activation of multiple cell competition regulators. Moreover, PLX4720 treatment promoted apical elimination of RasV12-transformed cells in vivo and suppressed the formation of potentially precancerous tumors. This is the first report demonstrating that a cell competition-promoting chemical drug facilitates apical elimination of transformed cells in vivo, providing a new dimension in cancer preventive medicine.

Potentially cancerous cells undergo live apical extrusion from normal monolayers and vSrc expression induces this in zebrafish epithelia. Here, the authors show that vSrc coordinates cytokinetic ring formation, cell cycle progression, junctional integrity, cell survival and apicobasal polarity to induce extrusion of transformed cells.

Summary: p53 is a tumor suppressor protein, and its missense mutations are frequently found in human cancers. During the multi-step progression of cancer, p53 mutations generally accumulate at the mid or late stage, but not in the early stage, and the underlying mechanism is still unclear. In this study, using mammalian cell culture and mouse ex vivo systems, we demonstrate that when p53R273H- or p53R175H-expressing cells are surrounded by normal epithelial cells, mutant p53 cells undergo necroptosis and are basally extruded from the epithelial monolayer. When mutant p53 cells alone are present, cell death does not occur, indicating that necroptosis results from cell competition with the surrounding normal cells. Furthermore, when p53R273H mutation occurs within RasV12-transformed epithelia, cell death is strongly suppressed and most of the p53R273H-expressing cells remain intact. These results suggest that the order of oncogenic mutations in cancer development could be dictated by cell competition. : Watanabe et al. demonstrate that mutant p53 cells undergo necroptosis and are eliminated from epithelia via cell competition with surrounding normal cells. Moreover, the eradication of mutant p53 cells is suppressed within RasV12-transformed epithelia, suggesting that the order of oncogenic mutations in cancer development could be dictated by cell competition. Keywords: cell competition, p53, necroptosis, p53R273H, p53R175H, RasV12, multi-step cancer progression, MDCK cells, mouse intestinal organoids

Summary: Recent studies have revealed that newly emerging transformed cells are often eliminated from epithelial tissues via cell competition with the surrounding normal epithelial cells. This cancer preventive phenomenon is termed epithelial defense against cancer (EDAC). However, it remains largely unknown whether and how EDAC is diminished during carcinogenesis. In this study, using a cell competition mouse model, we show that high-fat diet (HFD) feeding substantially attenuates the frequency of apical elimination of RasV12-transformed cells from intestinal and pancreatic epithelia. This process involves both lipid metabolism and chronic inflammation. Furthermore, aspirin treatment significantly facilitates eradication of transformed cells from the epithelial tissues in HFD-fed mice. Thus, our work demonstrates that obesity can profoundly influence competitive interaction between normal and transformed cells, providing insights into cell competition and cancer preventive medicine. : Sasaki et al. demonstrate using a cell competition mouse model that high-fat diet feeding substantially attenuates the frequency of apical elimination of RasV12-transformed cells from intestinal and pancreatic epithelia. These results indicate that obesity can profoundly influence competitive interaction between normal and transformed cells at the initial stage of carcinogenesis. Keywords: cell competition, obesity, EDAC, RasV12, apical extrusion, pancrease, lipid metabolism, chronic inflammation, Aspirin, cancer prevention

Objective: We aimed to evaluate the outcomes of growth-restricted fetuses with absent end-diastolic velocity in the umbilical arteries (UA-AEDV), and investigate the relationship between Doppler flow velocity waveforms in the ductus venosus (DV) and the clinical features. Materials and methods: This was a retrospective study of growth-restricted fetuses diagnosed with UA-AEDV delivered at our institution between 2013 and 2015. The time from diagnosis of UA-AEDV to delivery, postnatal survival, and developmental prognoses were the primary outcomes. The time lag between the occurrence of UA-AEDV and an abnormal increase in the DV pulsatility index (DV-PI) were investigated. We also examined the correlation between the DV-PI values immediately before birth and umbilical cord arterial pH at birth. Results: The median gestational age at birth among the 18 subjects was 28+2 (24+0–34+6) weeks, and the observation period between the first detection of UA-AEDV and delivery ranged from 0 to 35 days with a median of 8 days. Among the 18 infants, 15 (83%) survived, among whom 2 were diagnosed with a developmental disability. Gestational age at delivery was significantly lower in the poor outcome group. A positive correlation (correlation coefficient, 0.68) was observed between the umbilical artery pH and the last measured DV-PI. Conclusion: The time interval from initial detection of UA-AEDV to delivery is highly variable, and it is reasonable to manage these growth-restricted fetuses with UA-AEDV expectantly with careful surveillance for fetal well-being. Specifically, Doppler DV analysis is clinically valuable for their evaluation.

Abstract Background Recently, the association of plasma free amino acid (PFAA) profile and lifestyle-related diseases has been reported. However, few studies have been reported in large Asian populations, about the usefulness of PFAAs for evaluating disease risks. We examined the ability of PFAA profiles to evaluate lifestyle-related diseases in so far the largest Asian population. Methods We examined plasma concentrations of 19 amino acids in 8589 Japanese subjects, and determined the association with variables associated with obesity, blood glucose, lipid, and blood pressure. We also evaluated the PFAA indexes that reflect visceral fat obesity and insulin resistance. The contribution of single PFAA level and relevant PFAA indexes was also examined in the risk assessment of lifestyle-related diseases. Results Of the 19 amino acids, branched-chain amino acids and aromatic amino acids showed association with obesity and lipid variables. The PFAA index related to visceral fat obesity showed relatively higher correlation with variables than that of any PFAA. In the evaluation of lifestyle-related disease risks, the odds ratios of the PFAA index related to visceral fat obesity or insulin resistance with the diseases were higher than most of those of individual amino acid levels even after adjusting for potential confounding factors. The association pattern of the indexes and PFAA with each lifestyle-related disease was distinct. Conclusions We confirmed the usefulness of PFAA profiles and indexes as markers for evaluating the risks of lifestyle-related diseases, including diabetes mellitus, metabolic syndrome, dyslipidemia, and hypertension in a large Asian population.

Introduction. Although nonabsorbable woven tape has been widely used for cervical cerclage, technical difficulties that can occur with an effaced cervix because of the thickness of the tape, and the risks of local infection are two major concerns. This study investigated perinatal outcomes of pregnancies involving an emergency cervical cerclage using absorbable monofilament polydioxanone sutures, which is a narrow thread and protects against bacterial infection. Materials and Methods. We performed a chart review of patients who underwent emergency McDonald cerclage with polydioxanone sutures at our institution between 2007 and 2015. Gestational age at delivery, duration between cerclage and delivery, and neonatal prognosis were evaluated as primary outcomes. Results. Among the 23 patients (18 singleton and five twin pregnancies) evaluated, ultrasound-indicated (progressive cervical length shortening) were eight (35%) and physical examination-indicated (fetal membranes that prolapsed into the vagina or dilated cervix) were 15 patients (65%). The median gestational age at cerclage was 22+3 weeks (range, 17+5 to 25+3 weeks). Postoperative spontaneous abortion occurred in only one patient. The median gestational age at delivery was 32+5 weeks (range, 20+5 to 40+6 weeks). Extremely preterm delivery before 28 weeks of gestation occurred in four (17%) cases. Full-term delivery was achieved in 10 (42%) cases. The duration between cerclage and delivery ranged from 5 to 136 days (median, 77 days). Except for one case of spontaneous abortion, all newborns survived till hospital discharge. Conclusions. Although our series included some patients at high risk for spontaneous abortion and preterm delivery, satisfactory prolongation and favorable neonatal outcomes were achieved for most patients by using absorbable monofilament sutures, thus suggesting the efficacy of this type of suture for emergency cervical cerclage.

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Bone morphogenetic proteins (BMPs) regulate various biological processes, mostly mediated by cells of mesenchymal origin. However, the roles of BMPs in epithelial cells are poorly understood. Here, we demonstrate that, in polarized epithelial cells, BMP signals are transmitted from BMP receptor complexes exclusively localized at the basolateral surface of the cell membrane. In addition, basolateral stimulation with BMP increased expression of components of tight junctions and enhanced the transepithelial resistance (TER), counteracting reduction of TER by treatment with TGF-β or an anti-tumor drug. We conclude that BMPs maintain epithelial polarity via intracellular signaling from basolaterally localized BMP receptors.

Klippel-Trenaunay syndrome (KTS) is a rare congenital disease, and extensive cutaneous hemangiomas and abnormal venous vessels are characteristic. In our case, to manage her pregnancy with KTS, whole-body MRA was performed before delivery. A 29-year-old woman was referred at 28 weeks because of prominent vulvovaginal varicosities due to KTS. At 35 weeks, hypertrophy and multiple venous varicosities of her leg as well as massive vulvovaginal varicosities became prominent with a normal coagulation profile. Systematic MRAs revealed hemangiomas and varicosities in the right leg, the lower abdomen, and the pubic region, while no obvious AVM was detected around the bronchial tube and spine. We decided to deliver her baby by cesarean section at 37 weeks under general anesthesia, and a healthy baby was delivered. No blood transfusion was required. Prophylaxis against thrombosis was performed after the operation. She was discharged with her baby. Her vulvovaginal varicosities shrunk considerably one month later.

The Wnt/β-catenin signalling pathway shares a key component, β-catenin, with the cadherin-based adhesion system. The signalling function of β-catenin is conferred by a soluble cytoplasmic pool that is unstable in the absence of a Wnt signal, whilst the adhesion function is based on a cadherin-bound, stable pool at the membrane. The cadherin complex is dynamic, allowing for cell-cell rearrangements such as epithelial-mesenchymal transition (EMT), where the complex turns over through internalisation. Potential interplay between the two pools remains poorly understood, but cadherins are generally considered negative regulators of Wnt signalling because they sequester cytoplasmic β-catenin. Here we explore how cellular changes at EMT affect the signalling capacity of β-catenin using two models of EMT: hepatocyte growth factor (HGF) treatment of MDCK cells, and gastrulation in embryonic development. We show that EMT not only provides a pool of signalling-competent β-catenin following internalisation of cadherin, but also significantly facilitates activation of the Wnt pathway in response to both Wnt signals and exogenous β-catenin. We further demonstrate that availability of β-catenin in the cytoplasm does not necessarily correlate with Wnt/β-catenin pathway activity, since blocking endocytosis or depleting endogenous cadherin abolishes pathway activation despite the presence of β-catenin in the cytoplasm. Lastly we present data suggesting that cadherins are required for augmented activation of the Wnt/β-catenin pathway in vivo. This suggests that cadherins play a crucial role in β-catenin-dependent transcription.

During the initial stages of carcinogenesis, transformation events occur in a single cell within an epithelial monolayer. However, it remains unknown what happens at the interface between normal and transformed epithelial cells during this process. In Drosophila, it has been recently shown that normal and transformed cells compete with each other for survival in an epithelial tissue; however the molecular mechanisms whereby "loser cells" undergo apoptosis are not clearly understood. Lgl (lethal giant larvae) is a tumor suppressor protein and plays a crucial role in oncogenesis in flies and mammals. Here we have examined the involvement of Lgl in cell competition and shown that a novel Lgl-binding protein is involved in Lgl-mediated cell competition. Using biochemical immunoprecipitation methods, we first identified Mahjong as a novel binding partner of Lgl in both flies and mammals. In Drosophila, Mahjong is an essential gene, but zygotic mahjong mutants (mahj(-/-)) do not have obvious patterning defects during embryonic or larval development. However, mahj(-/-) cells undergo apoptosis when surrounded by wild-type cells in the wing disc epithelium. Importantly, comparable phenomena also occur in Mahjong-knockdown mammalian cells; Mahjong-knockdown Madin-Darby canine kidney epithelial cells undergo apoptosis, only when surrounded by non-transformed cells. Similarly, apoptosis of lgl(-/-) cells is induced when they are surrounded by wild-type cells in Drosophila wing discs. Phosphorylation of the c-Jun N-terminal kinase (JNK) is increased in mahj(-/-) or lgl(-/-) mutant cells, and expression of Puckered (Puc), an inhibitor of the JNK pathway, suppresses apoptosis of these mutant cells surrounded by wild-type cells, suggesting that the JNK pathway is involved in mahj- or lgl-mediated cell competition. Finally, we have shown that overexpression of Mahj in lgl(-/-) cells strongly suppresses JNK activation and blocks apoptosis of lgl(-/-) cells in the wild-type wing disc epithelium. These data indicate that Mahjong interacts with Lgl biochemically and genetically and that Mahjong and Lgl function in the same pathway to regulate cellular competitiveness. As far as we are aware, this is the first report that cell competition can occur in a mammalian cell culture system.

In various epithelial tissues, the epithelial monolayer acts as a barrier. To fulfill its function, the structural integrity of the epithelium is tightly controlled. When normal epithelial cells detach from the basal substratum and delaminate into the apical lumen, the apically extruded cells undergo apoptosis, which is termed anoikis. In contrast, transformed cells often become resistant to anoikis and able to survive and grow in the apical luminal space, leading to the formation of multilayered structures, which can be observed at the early stage of carcinogenesis. However, the underlying molecular mechanisms still remain elusive. In this study, we first demonstrate that S100A10 and ANXA2 (Annexin A2) accumulate in apically extruded, transformed cells in both various cell culture systems and murine epithelial tissues in vivo. ANXA2 acts upstream of S100A10 accumulation. Knockdown of ANXA2 promotes apoptosis of apically extruded RasV12-transformed cells and suppresses the formation of multilayered epithelia. In addition, the intracellular reactive oxygen species (ROS) are elevated in apically extruded RasV12 cells. Treatment with ROS scavenger Trolox reduces the occurrence of apoptosis of apically extruded ANXA2-knockdown RasV12 cells and restores the formation of multilayered epithelia. Furthermore, ROS-mediated p38MAPK activation is observed in apically delaminated RasV12 cells, and ANXA2 knockdown further enhances the p38MAPK activity. Moreover, the p38MAPK inhibitor promotes the formation of multilayered epithelia of ANXA2-knockdown RasV12 cells. These results indicate that accumulated ANXA2 diminishes the ROS-mediated p38MAPK activation in apically extruded transformed cells, thereby blocking the induction of apoptosis. Hence, ANXA2 can be a potential therapeutic target to prevent multilayered, precancerous lesions. [ABSTRACT FROM AUTHOR]