Colorectal cancer (CRC) is a malignancy with a high mortality and prevalence rate worldwide [1]. Although standard therapies have yielded good results in CRC patients, first-line chemotherapeutic agents such as 5-fluorouracil and oxaliplatin have certain side effects and resistance, resulting in the overall prognosis of CRC patients remaining poor after treatment with these agents [2]. Cafestol is a diterpenoid abundant in boiled and unfiltered coffee. Because of its antioxidant, cytotoxic, and antimutagenic potential, it is currently considered an effective component for the treatment of various forms of cancer [3]. Choi et al, discovered that cafestol inhibited proliferation and induced apoptosis in Caki cells [4]. Woo et al. found that cafestol increased the sensitivity of Bcl-2 inhibitor (ABT-737) to therapy and promoted apoptosis in several common cancer cell lines by regulating B-cell lymphoma-2 (Bcl-2) family proteins. They also found that cafestol did not impair the viability of normal human fibroblasts, suggesting more selective damage to tumor cells [5].

The specific molecular mechanism of cafestol's anti-cancer activity is still unknown, despite some advancements in the investigation of how it inhibits tumor growth. Autophagy is a non-apoptotic cell death mechanism characterized by the degradation of misfolded or deposited proteins and damaged organelles [6]. In recent years, the induction of autophagy has been considered a potential new target for cancer therapy. Some anticancer drugs and ionizing radiation can lead to autophagic cell death through the activation of autophagy. For example, triamcinolone acetonide and arsenic trioxide induce autophagic cell death in breast cancer cells Michigan Cancer Foundation-7 (MCF-7) and malignant glioma cells, respectively [7,8]. A new autophagy enhancer, IR58(A novel NIR small-molecule autophagy-enhancer), exerts significant anticancer effects on colon cancer by inducing autophagic cell death [9].

The Adenosine 5‘-monophosphate (AMP)-activated protein kinase(AMPK) pathway is important for many natural phytochemicals to regulate tumor cell proliferation. Cao [10] et al. found that narciclasine, an Amaryllidaceae isocarbostyril compound, can stimulate autophagy-dependent apoptosis by regulating the AMPK/ unc-51 like kinase 1 (ULK1) signaling pathway, and ultimately inhibit the proliferation of triple-negative breast cancer cells. Hu [11] et al. discovered that oleanolic acid Induces autophagy and apoptosis via the AMPK/s mammalian target of the rapamycin (mTOR) signaling pathway of Colon Cancer.

In summary, cellular autophagy plays an important role in the anti-cancer process. Therefore, the present study was conducted in vivo and in vitro to investigate whether cafestol inhibits the proliferation of colon cancer, and also to investigate in detail whether cafestol exerts its anti-cancer effects through the induction of the AMPK signaling pathway.