Naturally Isolated Sesquiterpene Lactone and Hydroxyanthraquinone Induce Apoptosis in Oral Squamous Cell Carcinoma Cell Line

SIMPLE SUMMARY: Globally, oral cancer is one of the leading causes of mortality, especially in Asian countries. Among the various types, oral squamous cell carcinoma (OSCC) is more prevalent. The available treatment regime available to tackle OSCC has side effects and resistance issues. This requires a study for an alternative pharmacophore as a potential anticancer compound with the least amount of toxicity. So, in this study, two natural compounds, costunolide (CE) and aloe emodin (AE), were screened for their anticancer potential against OSCC (CAL 27) cells. Both compounds, CE (32 µM) and AE (38 µM), inhibited the cancer cell lines at low doses, as comparable to fluorouracil (97.76 µM), and were found to be non-toxic on normal cells. The active compounds induced apoptosis, as well as morphological and nuclear changes in the cancer cells. At the gene level, these compounds enhance the expression of the apoptotic genes and reduces the expression of anti-apoptotic and metastatic genes. Thus, these compounds might have the potential to become promising anticancer candidates. ABSTRACT: Oral squamous cell carcinoma (OSCC) is one of the most prevalent cancers worldwide, especially in Asian countries. The emergence of its drug resistance and its side effects demands alternatives, to improve prognosis. Since the majority of cancer drugs are derived from natural sources, it provides a window to look for more biocompatible alternatives. In this study, two natural compounds, costunolide (CE) and aloe emodin (AE), were isolated from the stem of Lycium shawii. The compounds were examined for their anticancer and apoptotic potentials against OSCC (CAL 27) cells, using an in vitro analysis, such as a MTT assay, scratch assay, gene, and protein expressions. Both compounds, CE and AE, were found to be cytotoxic against the cancer cells with an IC(50) value of 32 and 38 µM, respectively. Moreover, the compounds were found to be non-toxic against normal NIH-3T3 cells and comparable with the standard drug i.e., 5-fluorouracil (IC(50) = 97.76 µM). These compounds were active against normal cells at higher concentrations. Nuclear staining displayed the presence of apoptosis-associated morphological changes, i.e., karyopyknosis and karyorrhexis in the treated cancer cells. Flow cytometry results further confirmed that these compounds induce apoptosis rather than necrosis, as the majority of the cells were found in the late apoptotic phase. Gene and protein expression analyses showed an increased expression of apoptotic genes, i.e., BAK, caspase 3, 6, and 9. Moreover, the compounds significantly downregulated the expression of the anti-apoptotic (BCL-2 L1), metastatic (MMP-2), and pro-inflammatory (COX-2) genes. Both compounds have shown promising anticancer, apoptotic, and anti-migratory activities against the OSCC cell line (i.e., CAL-27). However, further in vivo studies are required to explore these compounds as anticancer agents.