Efficacy of a Hypotonic Treatment for Peritoneal Dissemination from Gastric Cancer Cells: AnIn VivoEvaluation

Abstract

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.

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

“…When GC cells were incubated with DW, the number of viable cells actually decreased in an exposure time dependent manner. Furthermore, in the in vivo model, 20 min incubation of MKN45 cells with DW, instead of saline, markedly inhibited the formation of peritoneal nodules in nude mice, whereas the microscopic findings did not show any histological damages in the peritoneal mesothelial cells [ 10 ].…”

“…Regarding the difference in cytocidal effects between cancer and non-cancerous cells, our previous study have already shown that pancreatic cancer cells were more sensitive to hypotonic shock than human lung fibroblast WI38 cells [ 15 ]. Meanwhile, our previous in vivo experiments have also shown that peritoneal injection of DW did not severely damage the peritoneum and abdominal organs of mice, suggesting its safeness in an in vivo use [ 10 ]. Recently, many researchers including ours have reported the expression and role of ion and water channels/transporters for cancer progressions, which also involve in regulating cell volume [ 12 , 26 – 29 ].…”

“…The osmolality of the solution was measured using a freezing point osmometer (model 110, Fiske Associates, Norwood, MA), and determined as 300 mosmol/kgH 2 O for the isotonic NaCl solution, and 0 mosmol/kgH 2 O for DW. Autoclaved Milli-Q water was used for our DW working solution [ 10 – 15 ]. Graded hypotonic NaCl solutions were made by diluting the stock isotonic NaCl solution 2-fold, 4-fold, 8-fold and 16-fold with DW.…”

“…Thus, intraoperative peritoneal lavage plays an important role to reduce the risk of peritoneal recurrence because it can directly remove and kill such viable cancer cells. We have reported that peritoneal lavage with distilled water (DW) is a useful prophylactic treatment for peritoneal recurrence because severe hypotonic stimulation induces cell swelling followed by rupture of cancer cells [ 10 , 11 ]. However, cancer cells, as well as non-cancerous cells, have the inherent potential to avoid their ruptures even under hypotonic stimulation via the mechanism of regulatory volume decrease (RVD) which involves potassium and chloride ion transports [ 11 – 17 ].…”

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

“…Experimentally, DW exposure can rapidly increase cancer-cell volume, followed by cell rupture. The cytocidal effect of hypotonic stress on tumor cells has been demonstrated in various malignancies [19,20]. DW has been shown to be able to induce osmotic lysis in colorectal cancer cells [21,22], and more effectively kill cells than cytotoxic chemicals via disassociation with the resistant system of cancer cells.…”