DETERMINACIÓN DEL EFECTO DE Calendula officinalis SOBRE LOS NIVELES DE EXPRESIÓN DE MARCADORES TUMORALES EN CÁNCER DE PULMÓN

Abstract

Cancer is a disease characterized by uncontrolled cellular growth with high mortality rates and it is an important health problem around the world. In Mexico is considered the second cause of death. Therefore, currently there are several strategies based in chemotherapy, aimed to eliminating the tumor cells. Our research group has conducted a systematic discovery search for anticancer agents of natural origin showing cytotoxic activity on tumor cells, and probably they would be more effective diminishing side effects. Previous knowledge stating that plants such as Calendula officinalis have been used traditionally for the treatment of several diseases, we found that Calendula is considered to have antitumor effects. In search for innovative antitumor activities, we decided to search for a probable growth inhibition of Calendula hydroalcoholic extract on two cell lines: A549 from small cells lung adenocarcinoma and MRC-5 a non tumoral but immortalized pulmonary cell line. In order to determine changes in viability, MTT assays were performed, our results indicate that the Calendula extract alone, induces an increase of 40% viability on the A549 cells and does not induce changes in viability assays using MRC-5 cells. Proliferation assays were performed through the identification of a nuclear marker the protein PCNA, synthesized during cell cycle stages from G1 to S. PCNA detection results showed that the extract induces cell proliferation on A549. Also, Annexin V assays were performed and hydroalcoholic extract Calendula alone did not induce apoptosis. Besides, Calendula and Taxol were tested together in order to determine whether the combined treatment would cooperate or interfere with the basal cytotoxic effect of this antitumor drug (of choice in lung cancer). Results from combined treatments showed that the cytotoxic effect turns out to be more efficient than when using Taxol alone and cell changes are observed sooner (after 3-6 h of treatment). In addition, combined treatment induces apoptosis in A549 cells derived from cancer, while in the immortalized but non transformed lung cell line MRC-5, not any effect was observed. The above experimental work allows us to conclude that while the extract of Calendula alone induced cell proliferation and not apoptosis, the combined treatment with Taxol, surprisingly induces cytotoxic and apoptotic effect, differentially in A549 cells from tumor origin. Perhaps the Calendula hydroalcoholic extract`s content of flavonoids with antioxidant and pro-oxidant activity have something to do with the enhancement of cytotoxicity and apoptosis observed in our experiments. In the other hand the viability assays performed in both cell lines, using the channel-specific inhibitor KCNMA1 (charybdotoxin) showed no significant changes, suggesting that there is no modulation of cell proliferation after treatments using the KCNMA1 channel inhibitor.