Tillandsia usneoides Extract Decreases the Primary Tumor in a Murine Breast Cancer Model but Not in Melanoma

Simple Summary Cancer is a major public health problem worldwide and one of the major causes of mortality. Current therapies are becoming ineffective due to intratumoral heterogeneity, drug resistance, toxic effects, and relapses. Therefore, new therapeutic alternatives or their combination with conventional therapy are being explored. T. usneoides extract regulates the metabolism of the 4T1 and B16-F10 cell lines in an antagonistic manner with a significant impact on the tumor microenvironment, apparently related to the enhancement of an effective antitumor immune response, that allow the reduction of the 4T1 tumor but not of B16-F10. These data not only allow scientific validation of traditional knowledge but also take advantage of it to continue discovering mixtures of metabolites with antitumor and immunomodulatory activity. The main limits of current antitumor therapies are chemoresistance, relapses, and toxicity that impair patient quality of life. Therefore, the discovery of therapeutic alternatives, such as adjuvants to conventional therapy that modulate the intracellular oxidation state or the immune response, remains a challenge. Owing to traditional medicine, several uses of plants are known, indicating a promising antitumor and immunomodulatory effect. We evaluated the effect of ethanolic extract of T. usneoides in vitro and in vivo in models of 4T1 breast cancer and B16-F10 melanoma. In vitro evaluations with both cell lines showed that the extract has cytotoxic activity and induces apoptotic cell death. However, its effect on ROS production and glucose uptake was opposite. In vivo, only in the 4T1 model, a significant decrease in tumor size was found in animals treated with the extract, accompanied by an increase in dendritic cells and activated CD8(+) T cells, and a decrease in myeloid-derived suppressor-like cells (MDSC-LC) and Tregs in the tumor microenvironment. These results suggest that T. usneoides extract antagonistically regulates tumor metabolism of 4T1 vs. B16-F10, impacting the tumor microenvironment and effective antitumor immune response, leading to a reduction in 4T1 tumor size but not on B16-F10.

Automated summary

The ethanolic extract of T. usneoides has different effects on different types of tumor cells, inhibiting the growth of 4T1 tumor but not B16-F10 tumor. By enhancing the effective antitumor immune response, this extract is able to reduce tumor size and significantly impact the tumor microenvironment.