1. Introduction
Cancer is a deadly disease affecting the worldwide population. The major
problem in cancer treatment is the drug resistance and one of the
factors responsible for it is CSC (Holohan et al., 2013;
Torquato et al., 2017) . CSCs are those cancerous cells that possess a
unique capacity for self-renewal which makes them immortal(Chang, 2016) . Pluripotency-associated transcription factors
such as Oct 4, Sox-2, and Nanog play essential roles in maintenance of
stemness in these CSCs (Yun et al., 2017) . Due to this
stemness, CSCs lead to tumor heterogeneity and aggressiveness which
eventually leads to metastasis (Kusoglu & Biray Avcı, 2019) .
CSCs also cause the dormancy of the tumors resulting in treatment
resistance and increased chance of relapse (Steinbichler et al.,
2018) . CSCs are accountable for initiation of cancer as well as for
recurrence of treated tumors and hence have become crucial focal point
in cancer research during recent years (Cianciosi et al., 2018;
Oh et al., 2016) .
CSCs account for EMT, due to which the cells become more motile and
invasive. The reversal of EMT additionally contributes to tumor
proliferation. Aberration of various molecular and cellular signaling
pathways as well as altered metabolism of CSCs further exacerbate the
tumor heterogeneity. Thus, CSCs play an active role in cancer
dissemination (Yadav & Desai, 2019) .
Radiotherapy and chemotherapy are the conventional treatment methods for
any type of cancer. However, recently, several plants and plant-based
compounds are found to be attractive candidates in cancer therapy, owing
to their lower toxicity and higher selectivity against cancer cells(Torquato et al., 2017) . Phytomedicines are plant-based
compounds that are obtained either in isolated form or as a mixture of
different secondary metabolites to prevent and cure different diseases(Bonam et al., 2018) .
Phytomedicines possess various vitamins, minerals, and antioxidant
compounds due to which they exhibit a prospective to treat cancer(Bonam et al., 2018) . Herbal medicines and their bioactive
constituents have been used and tested for several past years.
Subsequently, it has been found that they depict anti-tumor activity by
modulating one of the signaling pathways, targeting efflux pump ABC
transporters or by inducing apoptosis and cell cycle arrest. Utilization
of plant natural product as anti-CSC agents has gained momentum
recently. Many studies have shown that medicinal plants, herbs or their
bioactive compounds reduce the stem-like characteristics of CSCs. They
interfere with EMT-genes, decrease invasiveness and migratory properties(Hermawan & Putri, 2018) . Here, we focused on recent updates
in discovery and use of phytomedicines against CSCs.