Irradiation induces mesenchymal traits in PANC-1 and BxPC3 pancreatic adenocarcinoma that are hindered by the antihistamine ranitidine

MOHAMAD NORA; GALARZA TAMARA; BOMBEN ANA; CRICCO GRACIELA; MARTIN GABRIELA

Congreso; IRPA15, 15th International Congress of the International Radiation Protection Association; 2021

We have previously set that a 2 Gy irradiation increased growth of human pancreatic PANC-1 xenografts in nude mice, while slowered growth of BxPC3 grafts. A 2 Gy irradiation also increased the development of lung metastasis in both tumor types. On the other hand, the antihistamine ranitidine (R) hindered growth of PANC-1 and BxPC3 tumors and the development of PANC-1 lung metastasis in nude mice.The aim of this work was to evaluate the effect of irradiation and R on epithelial to mesenchymal transition (EMT), a process associated with invasion and metastasis, in pancreatic tumors. Dedifferentiated PANC-1 and more differentiated BxPC3 tumors were irradiated (I) or not (C) with 2 Gy of gamma radiation, transplanted to non-irradiated mice, and treated with R 150 mg/kg.day, p.o. (I+R; C+R) or not (I; C). Immunohistochemistry was performed to evaluate the expression of EMT molecular markers (E-cadherin, vimentin, Slug) and of TGF-β1 (a major promoter of EMT). In PANC-1 tumors epithelial marker E-cadherin was not detected in any group, while transcription factor Slug nuclear expression was similar in all of them. In C-grafts we observed a big number of vimentin (mesenchymal marker) and TGF-β1 positive cells that was even bigger in I-tumors, but not in R and I+R. In BxPC3 only I-tumors did not show E-cadherin at cell membrane in the inner areas of slices. Very few cells expressed vimentin and TGF-β1 in C-tumors; this expression was enhanced in I-group but not changed in I+R or R. An increase in nuclear Slug and TGF-β1 was detected only in I-grafts. TGF-β1 correlated positively with vimentin in both tumor types. Nuclear Slug positively correlated with vimentin and TGF-β1 only in BxPC3. In order to perform in vitro studies, PANC-1 and BxPC3 cell cultures were pretreated (R) or not (C) for 1 day with R 20 µM, then irradiated (I; I+R) or not (C, C+R) with 2 Gy of gamma radiation. R treatment continued for 5 days; then, indirect immunofluorescence, Western blot or migration experiments were carried out. Results showed an increase in vimentin expression, intracellular TGF-β1 and cell migration in both I cell lines that was blocked by R. The transcription factor Slug showed the same behavior as in vivo experiments in both cell lines.In BxPC3 cells, E-cadherin was highly expressed in C, reduced in I, and partially re-expressed in I+R. C-PANC-1 cells expressed very low levels of E-cadherin that disappeared in I cells.In conclusion, 2 Gy of gamma radiation induced a gain of mesenchymal features related to EMT in both human pancreatic tumor cells. R treatment  pointing out the relevance of research on drugs that control both growth and metastasis.