Ethanolic leaf extract of Cleome spinosa induces apoptosis in Ehrlich ascites carcinoma cells through upregulation of p53 and down-regulation of Bcl-xL in vitro and in vivo

Cleome genus is commonly known as spider flower plant or cats whiskers, and is the largest genus of the family Cleomaceae, with around 200 species containing a range of remedial applications. Several species of Cleome genus show anti-cancer properties, however, nothing has been reported with genus spinosa, an anti-inflammatory and immunomodulatory plant. Thus, the present study examined the likely anti-cancer property of ethanolic leaf extract of Cleome spinosa (CSE) in Ehrlich ascites carcinoma (EAC) cells in vitro and in vivo. CSE treatment in vitro significantly caused higher percentage of death in EAC in a dose dependent manner compared to control groups (untreated and ethanol treated). Bright field, fluorescence and electron microscopies revealed apoptotic changes such as surface blebbings, nuclear fragmentation, chromatin condensation and apoptotic body formation, which probably could be the cause of death in EAC cells with CSE treatment. Apoptosis of CSE-treated EAC cells appeared to be mediated through upregulation of pro-apoptotic protein p53 and downregulation of anti-apoptotic protein, Bcl-xL expression, as ascertained through western blot both in vitro and in vivo. CSE was protective toward murine splenocytes by scavenging free radicals; it also reduced the ascitic tumor burden and increased the survival of the tumor-bearing mice compared to the control. Gas Chromatography-Mass Spectrometry (GCMS) analysis identified 43 phytocompounds in CSE. In silico molecular docking analysis indicated that a number of bioactive compounds, such as cycloartenol, stigmasterol, clionasterol, beta-sitosterol, lupenone, and sitostenone that were abundant in the CSE extract, exhibited strong binding affinities for the key apoptosis-regulating proteins, p53 and Bcl-xL. Thus, CSE derived-compounds appear to act as natural antioxidants, and have anti-cancer properties via induction of apoptosis in EAC possibly through upregulation of p53 and downregulation of Bcl-xL proteins in murine model. Hence, CSE could be considered as a promising natural compound for future cancer therapies.