Even though an increasing number of anticancer treatments have been discovered, the mortality rates of colorectal cancer (CRC) have still been high in the past few years. It has been discovered that melatonin has pro-apoptotic properties and counteracts inflammation, proliferation, angiogenesis, cell invasion, and cell migration. In previous studies, melatonin has been shown to have an anticancer effect in multiple tumors, including CRC, but the underlying mechanisms of melatonin action on CRC have not been fully explored. Thus, in this study, we investigated the role of autophagy pathways in CRC cells treated with melatonin. In vitro CRC cell models, HT-29, SW48, and Caco-2, were treated with melatonin. CRC cell death, oxidative stress, and autophagic vacuoles formation were induced by melatonin in a dose-dependent manner. Several autophagy pathways were examined, including the endoplasmic reticulum (ER) stress, 5′–adenosine monophosphate-activated protein kinase (AMPK), phosphoinositide 3-kinase (PI3K), serine/threonine-specific protein kinase (Akt), and mammalian target of rapamycin (mTOR) signaling pathways. Our results showed that melatonin significantly induced autophagy via the ER stress pathway in CRC cells. In conclusion, melatonin demonstrated a potential as an anticancer drug for CRC.

Cancer is a major cause of death worldwide, as exemplified by millions of cancer diagnoses every year. The use of chemotherapy in treating cancer has many disadvantages which include recurrence of cancer, associated with drug resistance, and severe side effects that are harmful to the patients. A better source of anticancer drugs can come from nature. Strobilanthes crispus (S. crispus) is a herbal medicinal plant that is indigenous in Madagascar and the Malay Archipelago. The plant possesses high vitamin and mineral content as well as phytochemicals—like phenols, catechins, tannins, and flavonoids—that are known to have therapeutic effects. Numerous preclinical studies have reported very versatile pharmacological effects of this plant, such as anticancer, antimicrobial, antioxidant, anti-angiogenesis, anti-diabetes, anti-ulcerogenic, and wound healing. Herein, this paper reviews the anticancer properties of S. crispus, providing information for future research and further exploration.