Inhibition of pulmonary metastasis by Emilia sonchifolia (L.) DC: An in vivo experimental study.

Background: Emilia sonchifolia (L.) DC is a widely distributed medicinal herb used mainly in the indigenous Ayurvedic system of medicine in India. This plant is one among the ten sacred plants of Kerala state in India, collectively known as Dasapushpam.

Purpose: To assess the therapeutic efficacy of this well-known medicinal plant in a catastrophic complication like metastatic cancer progression. This study further aimed to scientifically validate the traditional medicinal use of this sacred plant.

Study Design: Highly metastatic B16F10 melanoma will spontaneously metastasize in C57BL/6 mice and is accepted as a useful murine model for the study on metastasis. Three different experimental modalities of prophylactic, simultaneous and after tumour development were used for data accumulation and analysis.

Methods: Whole plant genuine extract of E. sonchifolia (25 mg/kg bodyweight) was administered intraperitoneally to C57BL/6 mice. Animals were sacrificed on 21st day after tumour induction and the lung tumour nodules were counted. Various lung and serum biochemical parameters along with major cytokine levels were recorded. Survival rate was monitored. Histopathology of the lung tissue and expression studies of the major genes involved in metastasis was also carried out.

Results: E. sonchifolia significantly inhibited pulmonary tumour formation and increased the life span of animals. Lung collagen hydroxyproline, uronic acid, hexosamine, serum sialic acid, γ-glutamyl transpeptidase, vascular endothelial growth factor (VEGF), granulocyte monocyte colony-stimulating factor and other cytokine levels were significantly lowered in the treated group of animals. Histopathological analysis was also correlated with these findings. E. sonchifolia down regulated the expression of matrix metalloproteinases; extracellular signal-regulated kinases and VEGF at the same time up regulated the expression of tissue inhibitor of matrix metalloproteinases.

Conclusion: Previous studies on E. sonchifolia proved its significant biological properties including anti-tumour, anti-inflammatory and antioxidant activities. Present report is so far the first study to demonstrate the anti-metastatic potential of this medicinal herb justifying its conventional use in the traditional medicine.