On the role of myosin-induced actin depolymerization during cell migration.

Mammalian cell migration in open spaces requires F-actin polymerization and myosin contraction. While many studies have focused on myosin's coupling to focal adhesion and stress fibers, the indirect effect of myosin contraction on cell migration through actin depolymerization is not well studied. In this work, we quantified how cell velocity and effective power output are influenced by the rate of actin depolymerization, which is affected by myosin contraction. In addition, we derived scaling laws to provide physical insights into cell migration. Model analysis shows that the cell migration velocity displays a biphasic dependence on the rate of actin depolymerization and myosin contraction. Our model further predicts that the effective cell energy output depends not only on the cell velocity but also on myosin contractility. The work has implications on in vivo processes such as immune response and cancer metastasis, where cells overcome barriers imposed by the physical environment.

A reduced 1D stochastic model of bleb-driven cell migration.

Blebs are pressure-driven protrusions that have been observed in cells undergoing apoptosis, cytokinesis, or migration, including tumor cells that use blebs to escape their organs of origin. Here, we present a minimal 1D model of bleb-driven cell motion that combines a simple mechanical model with turnover kinetics of the actin cortex and adhesions between the membrane and the cortex. The deterministic version of this model is used to study the properties of individual blebbing events. We further introduce stochastic turnover of the adhesions, which allows for spontaneous initiation of repeated blebbing events, thus leading to sustained cell travel. We explore how the main parameters of the system control the properties of the blebbing events and the speed of cell travel. Finally, we derive a further simplification by deriving a Langevin approximation to this stochastic model.

On the energy efficiency of cell migration in diverse physical environments.

In this work, we explore fundamental energy requirements during mammalian cell movement. Starting with the conservation of mass and momentum for the cell cytosol and the actin-network phase, we develop useful identities that compute dissipated energies during extensions of the cell boundary. We analyze 2 complementary mechanisms of cell movement: actin-driven and water-driven. The former mechanism occurs on 2-dimensional cell-culture substrate without appreciable external hydraulic resistance, while the latter mechanism is prominent in confined channels where external hydraulic resistance is high. By considering various forms of energy input and dissipation, we find that the water-driven cell-migration mechanism is inefficient and requires more energy. However, in environments with sufficiently high hydraulic resistance, the efficiency of actin-polymerization-driven cell migration decreases considerably, and the water-based mechanism becomes more efficient. Hence, the most efficient way for cells to move depends on the physical environment. This work can be extended to higher dimensions and has implication for understanding energetics of morphogenesis in early embryonic development and cancer-cell metastasis and provides a physical basis for understanding changing metabolic requirements for cell movement in different conditions.

Eversion stripping of the esophagus with intraesophageal insufflation-A case report.

INTRODUCTION: Patients with esophageal cancer frequently cannot tolerate thoracotomy due to their overall debilitated condition. Moreover, some patients have severe adhesions in the thoracic cavity. Eversion stripping of the esophagus is an option for resection in these patients. PRESENTATION OF CASE: A 64-year-old man was admitted to our institution with the chief complaint of epigastric pain. Endoscopic examination showed a protruding lesion 22cm from the incisors, with a superficial and circumferential mucosal irregularity on the distal side of the lesion. Biopsy revealed squamous cell carcinoma. Clinical stage was T1b(sm)N0M0, cStage I. In addition to the poor pulmonary status of the patient, adhesions in the intrathoracic cavity were predicted. The decision was made to perform esophageal resection without a thoracotomy. In order to ensure complete invagination of the esophagus, the esophagus was insufflated prior to stripping. The stripping process was observed with a gastroscope. During the stripping, the esophagus did not bunch up, and stripping was smooth and with minimal resistance. DISCUSSION: The stripping resection of the esophagus is an important option for the esophageal surgeon. In this case report, we describe a new eversion stripping method of the esophagus. This easy and reliable stripping method incorporates intraesophageal insufflation. CONCLUSION: The indications for blunt esophageal dissection without thoracotomy have been decreasing. On the other hand, our method seems to be useful in optimal case of stripping of esophagus.

Resection of the Gastric Tube Reconstructed through the Retrosternal Route without Sternotomy.

With advances of combined modality therapy, prognoses in esophageal cancer have been improving. After resection of esophageal cancer, the development of gastric tube cancer is a risk. While such cancer in an early stage can be cured endoscopically, total gastric tube resection is indicated in advanced stages. A 68-year-old man underwent subtotal esophagectomy reconstructed with a gastric tube through the retrosternal route. Gastric cancer was found one and a half years postoperatively. The gastric tube was resected without sternotomy. This is the first report of a patient undergoing resection of the gastric tube reconstructed through the retrosternal route without sternotomy.

Effects of Glia in a Triphasic Continuum Model of Cortical Spreading Depression.

Cortical spreading depression (SD) is a spreading disruption in brain ionic homeostasis during which neurons experience complete and prolonged depolarizations. SD is generally believed to be the physiological substrate of migraine aura and is associated with many other brain pathologies. Here, we perform simulations with a model of SD treating brain tissue as a triphasic continuum of neurons, glia and the extracellular space. A thermodynamically consistent incorporation of the major biophysical effects, including ionic electrodiffusion and osmotic water flow, allows for the computation of important physiological variables including the extracellular voltage (DC) shift. A systematic parameter study reveals that glia can act as both a disperser and buffer of potassium in SD propagation. Furthermore, we show that the timing of the DC shift with respect to extracellular [Formula: see text] rise is highly dependent on glial parameters, a result with implications for the identification of the propagating mechanism of SD.

Ambulatory laparoscopic cholecystectomy: An audit of day case vs overnight surgery at a community hospital in Japan.

AIM: To evaluate the applicability and safety of ambulatory laparoscopic cholecystectomy (LC) and to compare day case and overnight stay LC. METHODS: Data were collected retrospectively and consecutively for day case and overnight stay LC patients from July 1, 2009 to April 30, 2011. Outcomes were analyzed for patient demographics, operation time, blood loss during operation and frequency and reasons for unexpected or prolonged hospitalization in each group. RESULTS: There was no hospital mortality and no patient was readmitted with serious morbidity after discharge. 50 patients received a day case LC and 19 had an overnight stay LC. There was a significant difference in age between both groups (P < 0.02). There were no significant differences between the day case LC performed (n = 41) and failed (n = 9) groups and between the day case LC performed and the one night stay LC (n = 12) groups. There was a significant difference in age between the one night stay and more nights stay LC groups (P < 0.05). Thus, elderly patients showed a tendency to like to stay in hospital rather than being a day case. The proportion of unexpected or prolonged hospitalization was not significantly different between the day case and overnight stay LC groups, when the patient's request was excluded. CONCLUSION: Day case LC can be performed with a low rate of complications. In overnight stay patients, there are many who could be performed safely as a day case. Moreover, we need to take special care to treat elderly patients.

Adenocarcinoma arising in a colonic interposition following a total gastrectomy: report of a case.

A segment of the transverse colon can be used for gastric reconstruction after a total gastrectomy. This report presents the case of a 68-year-old woman with primary adenocarcinoma of the colon in a segment used for reconstruction after a total gastrectomy. The interposed colon developed colon carcinoma 9 years after the gastric reconstruction. The possibility of a primary carcinoma arising in a gastric colon interposition must be considered when employing the transverse colon as a gastric substitute.

microRNA expression profile in undifferentiated gastric cancer.

Prognosis of patients with undifferentiated gastric cancer is generally poor. The expression of various microRNAs (miRNAs) has not been comprehensively investigated in undifferentiated gastric cancer. Total RNA was extracted from the specimens of 42 undifferentiated gastric cancer tissues and paired normal gastric tissue. Quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR) was performed for a set of 72 miRNAs. The expression of each miRNA relative to the internal control RNA was determined using the 2-DeltaCt method. The expression levels of 3 miRNAs (mir-34b, mir-34c and mir-128a) were significantly upregulated and those of 3 miRNAs (mir-128b, mir-129 and mir-148) were downregulated in undifferentiated gastric cancer tissue when compared with those of the paired normal tissues. The probability of survival was significantly lower in patients with high expression levels of mir-20b or 150. There was a correlation between mir-27a and lymph node metastasis. Our investigation provides a list of candidate miRNAs that may be associated with the prognosis in undifferentiated gastric cancer patients. Further study is warranted to identify the target genes of these miRNAs and their function.

MicroRNA-21 induces cell proliferation and invasion in esophageal squamous cell carcinoma.

It has been suggested that microRNA-21 (miR-21) functions as an oncogene, as it is overexpressed in many types of tumors compared to adjacent normal tissues. However, the role of miR-21 has yet to be studied in esophageal squamous cell carcinoma (ESCC). miR-21 expression was quantified by real-time reverse transcription polymerase chain reaction in 38 ESCC specimens and their paired non-cancerous mucosa, and in 15 esophageal cancer cell lines (TE1-15). miR-21 expression levels in ESCC tissue were significantly higher than in the corresponding non-cancerous mucosa (6.873±12.664 vs. 1.000, p<0.0001). In patients with more advanced (T3 or T4) tumors, miR-21 expression levels were significantly higher than in those with less advanced (T1 or T2) tumors (P=0.0333). miR-21 expression levels in patients with more invasive infiltrative growth pattern (inf) ß tumors were significantly higher than in patients with less invasive infα tumors (P=0.0166). Among the cell lines studied, TE9 had the lowest and TE1 the highest expression of miR-21. Using the miRNA precursor or antisense miRNA inhibitor, we studied how the level of miR-21 influences the proliferation of ESCC cells. Cell proliferation of the anti-miR-21-transfected cell line was significantly lower, while that of the pre-miR-21-transfected cell line was significantly higher than in the control. In ESCC, miR-21 expression may be involved in tumor growth and invasion.

Targeting beta1 integrin restores sensitivity to docetaxel of esophageal squamous cell carcinoma.

Esophageal squamous cell carcinoma (ESCC) is a common and highly fatal cancer in Japan. Systemic chemotherapy is used, but some tumors show resistance to it. The mechanisms of tumor resistance to chemotherapy remain largely unknown. We determined the chemosensitivity of 15 ESCC cell lines (TE-1-5, TE-8-15, KYSE140 and KYSE150) to docetaxel by clonogenic and MTT assays. We used cDNA microarray analysis and quantitative RT-PCR to determine which genes might determine resistance to docetaxel. Small interfering RNA (siRNA) was used to suppress gene expression and its effect on the chemosensitivity of the cell was determined. The cell line with the most resistance to docetaxel was TE-2. Using microarray analysis, we identified beta1 integrin (ITGB1) to be overexpressed in this cell line. Higher expression of ITGB1 mRNA was significantly associated with docetaxel resistance (n=15, r2=0.66, P=0.0110). Suppression of ITGB1 expression using siRNA sensitized the TE-2 cells to docetaxel. These data suggest that overexpression of ITGB1 may be related to resistance to chemotherapy and that targeting ITGB1, particularly in patients on docetaxel therapy, may enhance the effect of chemotherapy in patients with ESCC.

PIK3CA mutation status in Japanese esophageal squamous cell carcinoma.

BACKGROUND: A somatic mutation of the PIK3CA (phosphatidylinositol 3-kinase catalytic subunit) gene has been found in human cancer patients. However, this mutation has not yet been extensively studied in esophageal squamous cell carcinomas. MATERIALS AND METHODS: We analyzed a mutation of the PIK3CA gene in 88 Japanese cases of esophageal squamous cell carcinomas that had all undergone surgery at the Department of Surgery II, Nagoya City University Medical School, between 1996 and 2003. The TE and KYSE series of cell lines are human esophageal cancer cell lines. Two PIK3CA mutation hot spots (exon 9 and exon 20) were analyzed by a real time polymerase chain reaction (PCR)-based assay and the data were confirmed by direct sequencing. We performed a cell proliferation assay to determine the effects of a PI3K inhibitor LY294002. RESULT: In exon 9, a somatic mutation was found in two patients (2.2%) and in two cell lines. The mutations included three E545K (G1633A) mutations and one E545Q (G1633C) mutation. However, in exon 20, no mutation was observed in our esophageal cancer patients. PI3K inhibitor (LY294002) inhibited the growth of an esophageal cancer cell line with a PIK3CA mutation (E545K) in vitro. CONCLUSIONS: We found LY294002 to reduce the proliferation of the esophageal cancer cell line in vitro. Importantly, a cell line with a PIK3CA gene mutation was more susceptible to a PI3K inhibition than those without any such mutation. Further functional analyses of the PIK3CA mutations are warranted to determine whether or not they may be potentially useful targets of therapy for esophageal cancer.

Decreased expression of RUNX3 is correlated with tumor progression and poor prognosis in patients with esophageal squamous cell carcinoma.

Runt-related transcription factor 3 (RUNX3) has been reported to be a candidate tumor suppressor gene in gastric cancer. However, in esophageal cancer, the role of RUNX3 has not been studied. The expression of RUNX3 mRNA was quantified by real-time reverse transcription polymerase chain reaction using Taq Man PCR in 15 esophageal cancer cell lines (TE1-15) and 70 esophageal squamous cell carcinoma (ESCC) specimens and their paired normal esophageal mucosa. The data were analyzed with reference to clinicopathological factors. Using specific primers, methylation of the promoter region of RUNX3 was examined. RUNX3 mRNA expression in ESCC tissue was significantly lower than that in the corresponding normal esophageal mucosa (3.913+/-4.617 vs. 7.795+/-15.361, P=0.0345). RUNX3 mRNA expression levels in locally invasive T4 tumors were significantly lower than those in less invasive T1-3 tumors (P=0.0454). Patients who had low RUNX3 mRNA expression levels had a significantly shorter survival after surgery compared with patients who had high RUNX3 mRNA expression (P=0.0299). Among the 15 esophageal cancer cell lines studied, one had methylation of the promoter region of RUNX3. Only 4 in 70 ESCC tumors had methylation in this region. In conclusion, RUNX3 expression may be involved in the tumor invasion and poor prognosis of patients with ESCC. The methylation of the RUNX3 promoter region in esophageal cancer is rare. A study on the mechanisms that underlie the reduced expression of RUNX3 in ESCC is warranted.

Expression of ECRG4 is an independent prognostic factor for poor survival in patients with esophageal squamous cell carcinoma.

In this study, we examined the expression of esophageal cancer-related gene 4 (ECRG4) mRNA and evaluated its clinical significance in esophageal squamous cell carcinoma (ESCC). ECRG4 mRNA expression was quantified by real-time RT-PCR in 63 ESCC and corresponding normal esophageal mucosal samples. ECRG4 mRNA expression levels were significantly lower in ESCC tissues compared with corresponding normal esophageal mucosa (P<0.0001), in patients with locally invasive T2-4 tumors compared with less invasive T1 tumors (P=0.0229) and in stage 4 tumors compared with stage 0-3 tumors (P=0.0120). Furthermore, low ECRG4 mRNA expression levels were associated with significantly shorter survival after surgery compared with high ECRG4 mRNA expression levels (P=0.0150) in ESCC patients. On the basis of multivariate analysis, we conclude that ECRG4 mRNA expression level could be a candidate for an independent prognostic factor for ESCC patients.

The overexpression of caveolin-1 and caveolin-2 correlates with a poor prognosis and tumor progression in esophageal squamous cell carcinoma.

Caveolin-1 (CAV1) and caveolin-2 (CAV2) are the major structural proteins of caveolae. We investigated the relationship between the clinicopathological factors of esophageal squamous cell carcinoma (ESCC) and the expression of CAV1 and CAV2. CAV1 and CAV2 expression were analyzed by quantitative reverse transcription-polymerase chain reaction (RT-PCR) in 15 esophageal cancer cell lines (TE1-15) and a normal esophageal epithelium cell line (Het-1A). CAV1 and CAV2 expression was examined by RT-PCR and immunohistochemical analysis in 47 ESCC specimens. High levels of CAV1 and CAV2 mRNA were detected in TE1-15, but neither CAV1 nor CAV2 mRNA were detected in Het-1A. In the ESCC samples CAV1 and CAV2 mRNA expression in the ESCC samples were significantly higher than in the corresponding normal esophageal mucosa (CAV1, P=0.0024; CAV2, P=0.0136). However, we could not find any significant relationship between CAV1 or CAV2 mRNA expression and clinicopathological factors. Immunostaining for CAV1 was positive in 13 of 47 patients (27.7%), whereas CAV2 was positive in 22 of 47 patients (46.8%). A significant correlation was observed between CAV1 and CAV2 immunostaining and T factor, lymphatic invasion, vein invasion and differentiation. The patients with positive staining for CAV1 or CAV2 had a significantly shorter survival than those with negative staining (P=0.0105 and 0.0424 for CAV1 and CAV2, respectively). These results suggest that positive staining for CAV1 and CAV2 could be a potentially useful prognostic marker of ESCC.

Frequent loss of the long arm of chromosome 18 in esophageal squamous cell carcinoma.

Esophageal squamous cell carcinoma (ESCC) is one of the most common and deadly cancers in Japan. In this study we performed fluorescent in situ hybridization (FISH) and loss of heterozygosity (LOH) analysis for chromosome 18q in ESCC cells to investigate allelic imbalance of chromosome 18q in ESCC. In the FISH analysis, only one signal for chromosome 18q was detected in TE-1 esophageal cancer cells, whereas two signals were detected in TE-2 cells. Two of five resected ESCC samples from patients showed loss of one copy of chromosome 18q. To construct a precise deletion map of chromosome 18q, LOH analysis was performed using 30 microsatellite markers localized to chromosome 18q. LOH was observed in 31 of 46 ESCC samples (67.4%) for at least one locus on chromosome 18q. LOH frequency for individual markers varied from 18.5% (D18S460) to 48.4% (D18S866). Thirteen of 46 ESCC samples (28.3%) showed the loss of most of the long arm of chromosome 18. Lymph node metastasis and vein invasion were significantly associated with the deletion of chromosome 18q. Loss of chromosome 18q may play an important role in the progression of ESCC.