Blockade of chloride ion transport enhances the cytocidal effect of hypotonic solution in gastric cancer cells

Intragastric free cancer cells may be attached to automatic staplers during anastomosis in patients with gastric cancer

BACKGROUND

Automatic staplers are often used to reconstruct the digestive tract during surgeries for gastric cancer. Intragastric free cancer cells adhering to automatic staplers may come in contact with the laparoscopic port area and progress to port site recurrence. This study aimed to investigate the presence/absence of cancer cells adhering to automatic staplers during gastric cancer surgery using cytological examinations. We further determined the positive predictive clinicopathological factors and clinical implications of free cancer cells attached to automatic staplers.

METHODS

This study included 101 patients who underwent distal gastrectomy for gastric cancer. Automatic staplers used for anastomosis in gastric cancer surgeries were shaken in 150 ml of saline solution to collect the attached cells. Papanicolaou stains were performed. We tested the correlation between cancer-cell positivity and clinicopathological factors to identify risk factors arising from the presence of attached cancer cells to the staplers.

RESULTS

Based on the cytology, cancer cells were detected in 7 of 101 (6.9%) stapler washing fluid samples. Univariate analysis revealed that circular staplers, type 1 tumors, and positive lymph nodes were significantly associated with higher detection of free cancer cells adhering to staplers. No significant differences in other factors were detected. Of the seven cases with positive cytology, one developed anastomotic recurrence.

CONCLUSIONS

Exfoliated cancer cells adhered to the automatic staplers used for anastomoses in 6.9% of the staplers used for distal gastrectomies in patients with gastric cancer. Staplers used for gastric cancer surgeries should be handled carefully.

Physiological roles of chloride ions in bodily and cellular functions

Physiological roles of Cl-, a major anion in the body, are not well known compared with those of cations. This review article introduces: (1) roles of Cl- in bodily and cellular functions; (2) the range of cytosolic Cl- concentration ([Cl-]c); (3) whether [Cl-]c could change with cell volume change under an isosmotic condition; (4) whether [Cl-]c could change under conditions where multiple Cl- transporters and channels contribute to Cl- influx and efflux in an isosmotic state; (5) whether the change in [Cl-]c could be large enough to act as signals; (6) effects of Cl- on cytoskeletal tubulin polymerization through inhibition of GTPase activity and tubulin polymerization-dependent biological activity; (7) roles of cytosolic Cl- in cell proliferation; (8) Cl--regulatory mechanisms of ciliary motility; (9) roles of Cl- in sweet/umami taste receptors; (10) Cl--regulatory mechanisms of with-no-lysine kinase (WNK); (11) roles of Cl- in regulation of epithelial Na+ transport; (12) relationship between roles of Cl- and H+ in body functions.

Potassium and Chloride Ion Channels in Cancer: A Novel Paradigm for Cancer Therapeutics

Cancer is a collection of diseases caused by specific changes at the genomic level that support cell proliferation indefinitely. Traditionally, ion channels are known to control a variety of cellular processes including electrical signal generation and transmission, secretion, and contraction by controlling ionic gradients. However, recent studies had brought to light important facts on ion channels in cancer biology.In this review we discuss the mechanism linking potassium or chloride ion channel activity to biochemical pathways controlling proliferation in cancer cells and the potential advantages of targeting ion channels as an anticancer therapeutic option.

Narrative review of theoretical considerations regarding HITHOC between past and future

Hyppocrates constructed the medicines-surgery-energy triangle which includes all therapeutical modalities. Hyperthermic intraoperative chemotherapy (HITHOC) is a synergy-based single stage multimodality treatment encompassing the locoregional manifestation of the systemic malignant process. Pleural space, thermal effect, lavage/irrigation and chemotherapy represent the basic science ports of the network hub: HITHOC. The malignant transformation and process of the pleural surface (and underlying lung) challenges space management and tissue control. Thermotherapy without local chemotherapy is insufficient, similar to the normothermic local irrigation aligned with anticancer agents. The local administration of combined heat-transfer fluid and chemotherapy with or without subsequent surgical removal offers reasonable outcome in extensive primary pleural neoplasms (malignant mesothelioma), advanced (> Stage IIIA) NSCLC, functionally inoperable lung cancer and pleural carcinosis from extrathoracic malignancies. Measured by symptom-free survival and the quality of life, HITHOC in its present form, offers a modest yet fully substantiated solution. HITHOC in combination with the local application of targeted therapy and/or immunotherapy administered in the pleural space are currently under investigation. Additional development including new acting substances, their solvents and the means regarding surgical delivery and anesthesiology techniques are sign posts up ahead. Level 2 evidence are required in order to stepping up the recommendation levels, rewriting protocols and guidelines, in which HITHOC earns its revered position in the decision making process it deserves.

ANO9 regulates PD-L2 expression and binding ability to PD-1 in gastric cancer

The function of ANO9 in gastrointestinal cancer remains unclear. We investigated the biological behaviors and clinical prognostic values of ANO9 in gastric cancer (GC). Knockdown experiments were performed on human GC cell lines using ANO9 siRNA. Eighty‐four primary tissue samples from patients with advanced GC were examined immunohistochemically (IHC). Knockdown of ANO9 reduced the progression of cancer cells in MKN7 and MKN74 cells. A microarray analysis revealed that ANO9 regulated PD‐L2 via interferon (IFN)‐related genes. We confirmed using flow cytometry that the depletion of ANO9 reduced the binding ability to PD‐1 by downregulating the expression of PD‐L2 in MKN7 and MKN74 cells. IHC revealed a correlation between the expression of ANO9 and PD‐L2 and also that the strong expression of ANO9 was an independent poor prognostic factor in patients with advanced GC. The present results indicate that ANO9 regulates PD‐L2 and binding ability to PD‐1 via IFN‐related genes in GC. Therefore, ANO9 has potential as a biomarker and target of immune checkpoint blockage (ICB) for GC.

The role of hyperthermic intraperitoneal chemotherapy in the treatment of spontaneously ruptured hepatocellular carcinoma: a pilot study

BACKGROUND

Spontaneous tumor rupture is a distinctive disease pattern in patients with hepatocellular carcinoma (HCC). The application of hyperthermic intraperitoneal chemotherapy (HIPEC) in spontaneously ruptured hepatocellular carcinoma (srHCC) is debatable. Our study aimed to compare the long-term outcomes of srHCC vs. nrHCC and to test the role of postoperative HIPEC in patients with srHCC after hepatectomy.

METHODS

From 2014 to 2018, PSM was performed to compare 57 patients who performed liver resection for srHCC and met the research criteria with 57 nrHCC patients selected from 446 consecutive patients. Then patients with srHCC were divided into two groups according to whether they underwent HIPEC after hepatectomy.

RESULTS

After 1:1 PSM, the clinical characteristics of the patients with srHCC and nrHCC were comparable. In terms of long-term outcomes, the nrHCC group had significantly longer OS (P=0.026) and DFS (P<0.001) than the srHCC group. Of the 57 srHCC patients, the HIPEC group showed added complications compared to the non-HIPEC group, including an increased length of hospital stay and higher in-hospital costs. However, there were no significant differences in the metastatic patterns of these recurrent patients, and there was no statistically significant difference in DFS (P=0.28) or OS (P=0.56) between the two groups.

CONCLUSIONS

The prognosis of ruptured HCC patients were worse than those of non-ruptured HCC patients. HIPEC may not be a robust treatment for srHCC now.

Scorpion Toxins and Ion Channels: Potential Applications in Cancer Therapy

Apoptosis, a genetically directed process of cell death, has been studied for many years, and the biochemical mechanisms that surround it are well known and described. There are at least three pathways by which apoptosis occurs, and each pathway depends on extra or intracellular processes for activation. Apoptosis is a vital process, but disturbances in proliferation and cell death rates can lead to the development of diseases like cancer. Several compounds, isolated from scorpion venoms, exhibit inhibitory effects on different cancer cells. Indeed, some of these compounds can differentiate between healthy and cancer cells within the same tissue. During the carcinogenic process, morphological, biochemical, and biological changes occur that enable these compounds to modulate cancer but not healthy cells. This review highlights cancer cell features that enable modulation by scorpion neurotoxins. The properties of the isolated scorpion neurotoxins in cancer cells and the potential uses of these compounds as alternative treatments for cancer are discussed.

Hyperthermic therapy using warm sterile water enhances cytocidal effects on bladder cancer cells

Objectives: To investigate whether warm sterile water enhances the cytocidal effect of hypotonic shock on bladder cancer cells that show resistance to sterile water.Methods: Four bladder cancer cell lines of varying grades (T24, RT4, J82, and RT112) were exposed to sterile water, and morphological changes were closely observed under microscopy. Changes in cell membrane integrity and cell viability after water exposure were measured to determine the effects of water-induced hypotonic shock. Additionally, the effects of warm sterile water were analyzed.Results: T24, RT4, and J82 cells started swelling immediately upon exposure to water, followed by rupture within five minutes. RT112 cells demonstrated limited hypotonic swelling with significantly less cell rupture after 10 min. The percentages of viable cells at 10 min were 1.6 ± 0.8%, 3.5 ± 3.5%, 5.0 ± 3.2%, and 22.0 ± 10.3% for T24, RT4, J82, and RT112, respectively. The percentage of viable cells with 48 °C sterile water at one minute was 0% for RT112 cells.Conclusions: These findings support the efficacy of sterile water against bladder cancer cells and reveal that warm sterile water enhances the cytocidal effects of hypotonic shock, potentially avoiding the need for radical surgery.

Effect of low temperature on the regulation of cell volume after hypotonic shock in gastric cancer cells

Although peritoneal lavage with distilled water performed after surgery prevents peritoneal seeding, cancer cells may avoid rupture under mild hypotonicity through regulatory volume decrease (RVD), which is the homeostatic regulation of ion and water transport. The aim of the present study was to investigate the effect of low temperature on cell volume and cell death under hypoosmolal conditions and determine the underlying molecular mechanisms in gastric cancer (GC). Three human GC cell lines (NUGC4, KATO‑III and MKN45) were exposed to hypotonic solutions, and the effects of low temperature on cell volume and viability were examined. Low temperature‑induced changes in membrane transporters were evaluated, and knockdown and overexpression experiments were conducted to determine their effects on cell volume during hypotonic stimulation. Low temperature (24˚C) during hypotonic stimulation inhibited RVD and enhanced the cytocidal effects on GC cells. The expression of leucine‑rich repeat containing protein A (LRRC8A), a component of a Cl‑ channel, was decreased, and aquaporin 5 (AQP5) expression was increased at low temperatures. LRRC8A knockdown markedly slowed the decrease in cell volume following cell swelling by hypotonic shock. AQP5 overexpression enhanced initial cell swelling after hypotonic shock and increased the final cell volume. These results suggest that a hypotonic solution at low temperature increased initial water influx via activation of AQP5 and decreased Cl‑ efflux via inhibition of LRRC8A. Therefore, low temperature enhanced the hypotonicity‑induced cytocidal effects on GC cells, and these results may contribute to the development of a novel lavage method effective in reducing peritoneal recurrence in GC.

Gastric washing by distilled water can reduce free gastric cancer cells exfoliated into the stomach lumen

PURPOSE

Intragastric free cancer cells in patients with gastric cancer have rarely been studied. The purpose of this study was to investigate the detection rate of intragastric free cancer cells in gastric washes using two types of solutions during endoscopic examination. We further clarified risk factors affecting the presence of exfoliated free cancer cells.

METHODS

A total of 175 patients with gastric cancer were enrolled. Lactated Ringer's solution (N = 89) or distilled water (DW; N = 86) via endoscopic working channel was sprayed onto the tumor surface, and the resultant fluid was collected for cytological examination. We compared the cancer-cell positivity rate between the two (Ringer and DW) groups. We also tested the correlation between cancer-cell positivity and clinicopathological factors in the Ringer group to identify risk factors for the presence of exfoliated cancer cells.

RESULTS

The cancer-cell positivity rate was significantly higher in the Ringer group than that in the DW group (58 vs 6%). Cytomorphology in the Ringer group was well maintained, but not in the DW group. The larger tumor size (≥ 20 mm) and positive lymphatic involvement were significant risk factors of exfoliated free cancer cells.

CONCLUSIONS

Cancer cells can be highly exfoliated from the tumor surface into the gastric lumen by endoscopic irrigation in large gastric cancer with lymphatic involvement. Gastric washing by DW can lead to cytoclasis of free cancer cells; therefore, it may minimize the possibility of cancer-cell seeding in procedures carrying potential risks of tumor-cell seeding upon transluminal communication, such as endoscopic full-thickness resection and laparoscopy-endoscopy cooperative surgery.

Safety and efficacy of dehydrated ethanol soaking of the operative field in the treatment of spontaneous hepatocellular carcinoma rupture

Background

The aim of our study was to evaluate the clinical safety and value of ethanol surgical field infiltration (ESFI), combined with distilled water peritoneal lavage (DWPL), after hepatectomy in patients with hepatocellular carcinoma (HCC) rupture.

Methods

Rat liver tissue samples were soaked in dehydrated ethanol for different soaking times, and 18 rats were assigned to three groups that underwent different soaking methods of the hepatectomy cut surface. We retrospectively reviewed 45 patients who underwent hepatectomy for treatment of ruptured HCC. Among these, EFSI combined with DWPL was used in 21 patients (DAW group), with only DWPL used in the other 24 patients (DW group). Clinical outcomes were compared between the two groups.

Results

For in vitro experiments, the depth of coagulation degeneration and necrosis increased with the duration of soaking. For in vivo experiments, rats in all three groups survived until postoperative day 7 without significant postoperative complication. In patients, the rate of post-operation complication was comparable between the two groups (P = 0.398), with no between-group differences in liver function levels. The incidence of peritoneal dissemination was significantly higher for DW than DAW group (P = 0.037). Kaplan–Meier test identified dehydrated ethanol treatment as a significant factor of disease-free survival (DFS) (P = 0.036). On univariate analysis, dehydrated ethanol treatment was associated with better prognostic outcomes, although it was not retained as an independent factor of patient outcome.

Conclusions

Dehydrated ethanol soaking of the cut surface of the hepatectomy could potentially lower the risk of metastasis and improve the effect of hepatectomy for ruptured HCC as well as showed potential therapeutic value for intraoperative iatrogenic rupture of HCC.

Electronic supplementary material

The online version of this article (10.1186/s12957-018-1390-x) contains supplementary material, which is available to authorized users.

Blockade of potassium ion transports enhances hypotonicity-induced cytocidal effects in gastric cancer

Background

Peritoneal lavage with distilled water has been used for surgeries of various cancers to reduce peritoneal recurrence. This study examined whether blockade of potassium ion transports enhances hypotonicity-induced cytocidal effects in gastric cancer (GC).

Results

A potassium channel blocker inhibited the occurrence of regulatory volume decrease (RVD) induced by mild hypotonic stimulation, and significantly enhanced cytocidal effects on GC cells. Incubating MKN45 cells with hypotonic solutions containing a potassium channel blocker significantly reduced the formation of peritoneal metastases in nude mice.

Methods

The three human GC cell lines (HGC-27, Kato III, and MKN45) were exposed to mild hypotonic solutions, and the effects of blockade of potassium ion transports during hypotonic stimulation on cell volume changes and cell viabilities were examined. In the in vivo study, MKN45 cells stimulated with mild hypotonic solutions were intraperitoneally injected into nude mice, and the effects of blockade of potassium ion transports during hypotonic stimulation on the formation of peritoneal metastases were evaluated.

Conclusions

Blockade of potassium ion transports enhances hypotonicity-induced cytocidal effects on GC cells, which may contribute to development of a novel lavage method for further reduction of peritoneal recurrence in GC.

Regulation of osmolality for cancer treatment

Disseminated metastasis is associated with a poor prognosis, and its management in the peritoneal or pleural cavity is crucial in the treatment of cancer. Recent studies show that ion and water transporters play important roles in fundamental cellular functions, including the regulation of cell volume that would be involved in the cancer process. Here, we review the evidence for hypotonic treatments of cancer and evaluate the potential of the cellular physiological approach in clinical management. The regulation of extracellular osmolality is a promising method, with several studies demonstrating the cytocidal effects of hypotonic solution on cancer cells. Peritoneal lavage with distilled water (DW) during surgery is reported to improve the survival rate of patients with spontaneously ruptured hepatocellular carcinoma. The in vitro studies included in this review also indicate the cytocidal effects of hypotonic shock on esophageal, gastric, colonic, pancreatic, and liver cancer cells with several unique methods and apparatuses, such as a differential interference contrast microscope connected to a digital video camera, a high-resolution flow cytometer and re-incubation analysis. The in vivo studies demonstrate the safeness of a peritoneal injection of DW into mice and indicate that the development of dissemination nodules can be prevented by the pre-incubation of cancer cells with DW or the peritoneal injection of DW. We also demonstrate that the blockade of Cl- channels/transporters enhances the cytocidal effects of hypotonic shock by inhibiting regulatory volume decrease in various cancer cells. A deeper understanding of molecular mechanisms may lead to the discovery of these cellular physiological approaches as a novel therapeutic strategy for disseminated metastasis.

Heat shock exerts anticancer effects on liver cancer via autophagic degradation of aquaporin 5

Previous studies described that the expression of aquaporin 5 (AQP5) was altered in tumors of various organs. AQP5 is attracting attention as a new cancer therapeutic target. In the present study, heat shock-induced changes in AQP5 expression were evaluated by immunofluorescent staining (IF) and western blotting (WB) of liver cancer cells. AQP5 knockdown experiments or a heat shock treatment were conducted, and their effects on cell volume, proliferation, cell cycle, the activity of apoptosis and migration/invasion were compared. Cycloheximide (CHX) chase experiments and double IF of AQP5 and light chain 3B (LC3B) were performed to investigate the mechanisms underlying changes in AQP5 expression. The results showed that IF and WB revealed decrease in AQP5 expression on cellular membranes and in the cytoplasm of heated cells. AQP5 knockdown and heat shock similarly decreased cell volume, suppressed migration/invasion and proliferation, and induced early apoptosis and partial G0/G1 arrest. CHX chase experiments revealed that heat shock accelerated the degradation of AQP5, which was rescued under CHX and the autophagy inhibitor, bafilomycin A1 (BafA1). Double IF showed the co-localization of AQP5 and LC3B on BafA1-treated heated cells. In conclusion, we demonstrated that heat shock decreased AQP5 on cellular membranes and in the cytoplasm by activating autophagic degradation, and heat shock and AQP5 knockdown exerted similar anticancer effects, suggesting that heat shock exerts anticancer effects via the autophagic degradation of AQP5.

The cytotoxic synergy of nanosecond electric pulses and low temperature leads to apoptosis

Electroporation by nanosecond electric pulses (nsEP) is an emerging modality for tumor ablation. Here we show the efficient induction of apoptosis even by a non-toxic nsEP exposure when it is followed by a 30-min chilling on ice. This chilling itself had no impact on the survival of U-937 or HPAF-II cells, but caused more than 75% lethality in nsEP-treated cells (300 ns, 1.8-7 kV/cm, 50-700 pulses). The cell death was largely delayed by 5-23 hr and was accompanied by a 5-fold activation of caspase 3/7 (compared to nsEP without chilling) and more than 60% cleavage of poly-ADP ribose polymerase (compared to less than 5% in controls or after nsEP or chilling applied separately). When nsEP caused a transient permeabilization of 83% of cells to propidium iodide, cells placed at 37 °C resealed in 10 min, whereas 60% of cells placed on ice remained propidium-permeable even in 30 min. The delayed membrane resealing caused cell swelling, which could be blocked by an isosmotic addition of a pore-impermeable solute (sucrose). However, the block of swelling did not prevent the delayed cell death by apoptosis. The potent enhancement of nsEP cytotoxicity by subsequent non-damaging chilling may find applications in tumor ablation therapies.

Nuclear myosin I regulates cell membrane tension

Plasma membrane tension is an important feature that determines the cell shape and influences processes such as cell motility, spreading, endocytosis and exocytosis. Unconventional class 1 myosins are potent regulators of plasma membrane tension because they physically link the plasma membrane with adjacent cytoskeleton. We identified nuclear myosin 1 (NM1) - a putative nuclear isoform of myosin 1c (Myo1c) - as a new player in the field. Although having specific nuclear functions, NM1 localizes predominantly to the plasma membrane. Deletion of NM1 causes more than a 50% increase in the elasticity of the plasma membrane around the actin cytoskeleton as measured by atomic force microscopy. This higher elasticity of NM1 knock-out cells leads to 25% higher resistance to short-term hypotonic environment and rapid cell swelling. In contrast, overexpression of NM1 in wild type cells leads to an additional 30% reduction of their survival. We have shown that NM1 has a direct functional role in the cytoplasm as a dynamic linker between the cell membrane and the underlying cytoskeleton, regulating the degree of effective plasma membrane tension.

Inhibition of Regulatory Volume Decrease Enhances the Cytocidal Effect of Hypotonic Shock in Hepatocellular Carcinoma

Background: Hypotonic shock induces cytocidal effects through cell rupture, and cancer therapy based on this mechanism has been clinically administered to hepatocellular carcinoma patients. We herein investigated the effectiveness of hypotonic shock combined with the inhibition of regulatory volume decrease as cancer therapy for hepatocellular carcinoma.

Methods: Morphological changes in human hepatocellular carcinoma cell lines were observed under a differential interference contrast microscope connected to a high-speed digital video camera. Cell volume changes under hypotonic shock with or without chloride, potassium, or water channel blockers were observed using a high-resolution flow cytometer. In order to investigate cytocidal effects, the number of surviving cells was compared after exposure to hypotonic solution with and without each channel blocker (re-incubation experiment).

Results: Video recordings showed that cells exposed to distilled water rapidly swelled and then ruptured. Cell volume measurements revealed regulatory volume decrease under mild hypotonic shock, whereas severe hypotonic shock increased the number of broken fragments as a result of cell rupture. Moreover, regulatory volume decrease was inhibited in cells treated with each channel blocker. Re-incubation experiments showed the cytocidal effects of hypotonic shock in cells exposed to hypotonic solution, and additional treatments with each channel blocker enhanced these effects.

Conclusion: The inhibition of regulatory volume decrease with chloride, potassium, or water channel blockers may enhance the cytocidal effects of hypotonic shock in hepatocellular carcinoma. Hypotonic shock combined with the inhibition of regulatory volume decrease was a more effective therapy than hypotonic shock alone.

Tumor suppression in basal keratinocytes via dual non-cell-autonomous functions of a Na,K-ATPase beta subunit

The molecular pathways underlying tumor suppression are incompletely understood. Here, we identify cooperative non-cell-autonomous functions of a single gene that together provide a novel mechanism of tumor suppression in basal keratinocytes of zebrafish embryos. A loss-of-function mutation in atp1b1a, encoding the beta subunit of a Na,K-ATPase pump, causes edema and epidermal malignancy. Strikingly, basal cell carcinogenesis only occurs when Atp1b1a function is compromised in both the overlying periderm (resulting in compromised epithelial polarity and adhesiveness) and in kidney and heart (resulting in hypotonic stress). Blockade of the ensuing PI3K-AKT-mTORC1-NFκB-MMP9 pathway activation in basal cells, as well as systemic isotonicity, prevents malignant transformation. Our results identify hypotonic stress as a (previously unrecognized) contributor to tumor development and establish a novel paradigm of tumor suppression.

Carbonic Anhydrase XII as an Independent Prognostic Factor in Advanced Esophageal Squamous Cell Carcinoma

BACKGROUND

Although recent studies described important roles for carbonic anhydrase (CA) XII in epithelial carcinogenesis and tumor behavior, a consensus has not yet been reached regarding its clinicopathological significance in esophageal squamous cell carcinoma (ESCC). In the present study, we investigated its prognostic significance in ESCC.

MATERIALS AND METHODS

An immunohistochemical analysis was performed on 70 primary tumor samples obtained from ESCC patients who underwent esophagectomy, and the relationships between the expression of CA XII and various clinicopathological features or prognosis were analyzed.

RESULTS

Immunohistochemical staining showed that CA XII was primarily found in the cell membranes of carcinoma cells. Although the expression of CA XII was related to the pT category, it had no prognostic impact. We then examined the expression of CA XII according to the pT category. In pT2-3 ESCC, the 3-year survival rate of patients with the high grade expression of CA XII (29.1 %) was significantly lower than that of patients with the low grade expression of CA XII (70.3 %). Furthermore, a multivariate analysis demonstrated that the expression of CA XII was one of the most important independent prognostic factors following radical esophagectomy in pT2-3 ESCC.

CONCLUSION

These results suggest that the expression of CA XII may be a valuable prognostic factor for patients with advanced ESCC. The results of the present study provide an insight into the role of CA XII as a biomarker in ESCC.

Dialysate Lavage: An Alternative Solution for Reducing the Peritoneal Implantation of Poorly Differentiated Gastric Cancer Cells

BACKGROUND

Peritoneal lavage after cancer surgery is performed to reduce microscopic residual tumors in the peritoneum. This study evaluated the effects and mechanism of dialysate lavage in reducing the peritoneal implantation of gastric cancer cells.

METHODS

Gastric cancer cells (MKN45 or AGS) were cultured with 1.5% peritoneal dialysate (PD) or normal saline (NS) for 30 min. The in vitro cell susceptibility to dialysate, including cell proliferation, cell death, cleaved PARP expression, and mitochondrial membrane potential, was evaluated. A murine model for gastric cancer cell peritoneal seeding was established to test the effects of PD and NS lavage on animal survival and tumor growth.

RESULTS

A significant decrease in cell proliferation in PD and NS (75.2 ± 0.1 vs. 12.4 ± 0.2% in MKN45, p = 0.009; 58.2 ± 0.01 vs. 28.0 ± 0.01% in AGS, p = 0.008), an increase in mitochondrial permeability transition (93.0 ± 2.6 vs. 18.0 ± 2.9% in MKN45, p = 0.021; 86.8 ± 4.6 vs. 47.7 ± 10.2% in AGS, p < 0.001), and an increase in the expression of cleaved PARP and increased death (25.6 ± 9.4 vs. 16.9 ± 5.3% in MKN45, p = 0.031; 39.5 ± 5.1 vs. 20.9 ± 3.9% in AGS, p = 0.008) were recorded for gastric cancer cells separately exposed to PD and NS. Twenty-four days after inoculating MKN45 cells (5 × 10(6)/0.1 ml) in the peritoneal cavity, the average number of seeded tumors was 67.3 ± 10.8, 92.3 ± 6.0, and 29.2 ± 16.7 (p = 0.032), and the total weight of tumors was 0.98 ± 0.21, 0.58 ± 0.12, and 0.31 ± 0.17 g (p = 0.008), respectively, for mice receiving sham operation, NS lavage, and PD lavage. The 45-day survival rate for the PD lavage group was 22% compared to 0% for the sham injection and NS lavage groups (p = 0.034).

CONCLUSION

PD induced significant cytotoxicity in gastric cancer cells that was related to mitochondrial perturbation. The use of PD lavage was effective in reducing the peritoneal implantation of gastric cancers in a murine model.

Evaluation of the efficacy of peritoneal lavage with distilled water in colorectal cancer surgery: in vitro and in vivo study

BACKGROUND

Peritoneal lavage with distilled water has been performed during colorectal cancer surgery. This study investigated the cytocidal effects of hypotonic shock in vitro and in vivo in colorectal cancer cells.

METHODS

Three human colorectal cancer cell lines, DLD1, HT29, and CACO2, were exposed to distilled water, and morphological changes were observed under a differential interference contrast microscope connected to a high-speed digital video camera. Cell volume changes were assessed using a high-resolution flow cytometer. Re-incubation experiments were performed to investigate the cytocidal effects of distilled water. In the in vivo experiment, cancer cells after hypotonic shock were injected intraperitoneally into mice and the degree of established peritoneal metastasis was subsequently evaluated. The effects of the blockade of Cl(-) channels on these cells during hypotonic shock were also analyzed.

RESULTS

Morphological observations revealed a rapid cell swelling followed by cell rupture. Measurements of cell volume changes showed that mild hypotonic shock induced regulatory volume decrease (RVD) while severe hypotonic shock broke cells into fragments. Re-incubation experiments demonstrated the cytocidal effects of hypotonicity. In vivo experiments revealed the absence of peritoneal dissemination in mice in the distilled water group, and its presence in all mice in the control group. The blockade of Cl(-) channels increased cell volume by inhibiting RVD and enhanced cytocidal effects during mild hypotonic shock.

CONCLUSIONS

These results clearly support the efficacy of peritoneal lavage with distilled water during colorectal cancer surgery and suggest that regulating of Cl(-) transport may enhance the cytocidal effects of hypotonic shock.

Claudin 1 mediates tumor necrosis factor alpha-induced cell migration in human gastric cancer cells

AIM: To investigate the role of claudin 1 in the regulation of genes involved in cell migration and tumor necrosis factor alpha (TNF-α)-induced gene expression in human gastric adenocarcinoma cells.

METHODS: Knockdown experiments were conducted with claudin 1 small interfering RNA (siRNA), and the effects on the cell cycle, apoptosis, migration and invasion were analyzed in human gastric adenocarcinoma MKN28 cells. The gene expression profiles of cells were analyzed by microarray and bioinformatics.

RESULTS: The knockdown of claudin 1 significantly inhibited cell proliferation, migration and invasion, and increased apoptosis. Microarray analysis identified 245 genes whose expression levels were altered by the knockdown of claudin 1. Pathway analysis showed that the top-ranked molecular and cellular function was the cellular movement related pathway, which involved MMP7, TNF-SF10, TGFBR1, and CCL2. Furthermore, TNF- and nuclear frctor-κB were the top-ranked upstream regulators related to claudin 1. TNF-α treatment increased claudin 1 expression and cell migration in MKN28 cells. Microarray analysis indicated that the depletion of claudin 1 inhibited 80% of the TNF-α-induced mRNA expression changes. Further, TNF-α did not enhance cell migration in the claudin 1 siRNA transfected cells.

CONCLUSION: These results suggest that claudin 1 is an important messenger that regulates TNF-α-induced gene expression and migration in gastric cancer cells. A deeper understanding of these cellular processes may be helpful in establishing new therapeutic strategies for gastric cancer.

Cellular physiological approach for treatment of gastric cancer

Recent studies show that ion channels/transporters play important roles in fundamental cellular functions that would be involved in the cancer process. We review the evidence for their expression and functioning in human gastric cancer (GC), and evaluate the potential of cellular physiological approach in clinical management. Various types of ion channels, such as voltage-gated K⁺ channels, intracellular Cl^- channels and transient receptor potential channels have been found to express in GC cells and tissues, and to control cell cycles. With regard to water channels, aquaporin 3 and 5 play an important role in the progression of GC. Regulators of intracellular pH, such as anion exchanger, sodium-hydrogen exchanger, vacuolar H⁺-ATPases and carbonic anhydrases are also involved in tumorigenesis of GC. Their pharmacological manipulation and gene silencing affect cellular behaviours, suggesting their potential as therapeutic targets for GC. Our studies indicate the intracellular Cl^- concentration could act as a mediator of cellular signaling and control cell cycle progression in GC cells. Further, we demonstrate the cytocidal effects of hypotonic shock on GC cells, and indicate that the blockade of Cl^- channels/transporters enhances these effects by inhibiting regulatory volume decrease. A deeper understanding of molecular mechanisms may lead to the discovery of these cellular physiological approaches as a novel therapeutic strategy for GC.

Efficacy of a hypotonic treatment for peritoneal dissemination from gastric cancer cells: an in vivo evaluation

The aim of the present study was to determine the efficacy of a hypotonic treatment for peritoneal dissemination from gastric cancer cells using an in vivo model. We firstly evaluated the toxicity of a peritoneal injection of distilled water (DW) (2 mL for 3 days) in mice. Macroscopic and microscopic examinations revealed that the peritoneal injection of DW did not severely damage the abdominal organs of these mice. MKN45 gastric cancer cells preincubated with NaCl buffer or DW for 20 minutes in vitro were then intraperitoneally injected into nude mice, and the development of dissemination nodules was analyzed. The total number, weight, and volume of the dissemination nodules were significantly decreased by the DW preincubation. We then determined whether the peritoneal injection of DW inhibited the establishment of peritoneal dissemination. After a peritoneal injection of MKN45 cells into nude mice, NaCl buffer or DW was injected into the abdominal cavity for 3 days. The total volume of dissemination nodules was significantly lower in DW-injected mice than in NaCl-injected mice. In conclusion, we demonstrated the safeness of a peritoneal injection of DW. Furthermore, the development of dissemination nodules from gastric cancer cells was prevented by a preincubation with or peritoneal injection of DW.