Adenine inhibits growth of hepatocellular carcinoma cells via AMPK-mediated S phase arrest and apoptotic cascade

Abstract

Background: Adenine exhibits potential anticancer activity against several types of malignancies. However, whether adenine has anticancer effects on hepatocellular carcinoma (HCC) cells is incompletely explored. Methods: Human HCC cell lines HepG2 and SK-Hep-1 (p53-wild type) and Hep3B (p53-deficient) were used as cell model. Cell growth and cell cycle distribution were determined using MTT assay and flow cytometric analysis, respectively. Protein expression and phosphorylation were assessed by Western blot. Involvement of AMP-activated protein kinase (AMPK) was evaluated using specific inhibitor and small inhibitory RNA (siRNA). Results: Adenine treatments (0.5 -2 mM) clearly decreased the cell growth of Hep G2 and SK-Hep-1 cells to 72.5 ± 3.4% and 71.3 ± 4.6% of control, respectively. In parallel, adenine also induced sub-G1 and S phase accumulation in both HCC cells. However, adenine did not affect the cell growth and cell cycle distribution of Hep3B cell. Western blot analysis showed that adenine reduced expression of cyclin A/D1 and cyclin-dependent kinase (CDK)2 and upregulated p53, p21, Bax, PUMA, and NOXA in HepG2 cell. Moreover, adenine induced AMPK activation that was involved in the p53-associated apoptotic cascade in HepG2 cells. Inhibition of AMPK activation or knockdown of AMPK restored the decreased cell growth of HepG2 and SK-Hep-1 cells in response to adenine. Conclusions: These findings reveal that adenine reduces the cell growth of HepG2 and SK-Hep-1 but not Hep3B cells, attributing to the AMPK/p53-mediated S phase arrest and apoptosis. It suggests that adenine has anticancer potential against p53-wild type HCC cells and may be beneficial as an adjuvant for HCC treatment.

Adenine Inhibits the Invasive Potential of DLD-1 Human Colorectal Cancer Cell via the AMPK/FAK Axis

“…Our previous studies indicated that AMPK plays an important role in the anticancer activity of adenine [ 6 , 15 ]. Thus, the involvement of AMPK in the adenine-inhibited integrin/FAK cascade was investigated.…”

“…The integrin/FAK/Src axis is strongly associated with the transformation, progression, and metastasis of tumors [ 13 ], and the activation of the FAK/Src cascade by integrin subsequently promotes cell motility and the invasiveness of cancer cells [ 14 ]. Although adenine shows antiproliferative activity on hepatocellular carcinoma cells and chronic myelogenous leukemia cells via AMPK-mediated cascade [ 6 , 15 ], whether adenine has anti-invasion activity on CRC has not yet been investigated. In this study, we aimed to explore the inhibitory effects of adenine on the invasiveness of DLD-1 and SW480 cells, which are highly metastatic and tumorigenic CRC cells, and its underlying mechanism.…”

Biochemical and Molecular Investigation of In Vitro Antioxidant and Anticancer Activity Spectrum of Crude Extracts of Willow Leaves Salix safsaf

“…The mechanism-of-action for purine compounds has been postulated to proceed through the activation of 5′-adenosine monophosphate-activated protein kinase (AMPK), a key cancer chemotherapeutic target. Thus, the purine analog ENERGI-F706 has been recently shown to exhibit significant AMPK-mediated anticancer activities against renal and HCC cells leading to cell cycle arrest and engagement of the apoptotic cascade [ 51 , 53 ]. Cytokinin ribosides (e.g., kinetin riboside, isopentenyladenosine and benzylaminopurine riboside), but not cytokinin, have been reported to result in significant in vitro anti-leukemic effects and the enhancement of apoptosis and its biochemical markers including reduction in intracellular ATP content, loss of mitochondrial membrane potential and generation of ROS [ 54 ].…”

Adenine Inhibits B16-F10 Melanoma Cell Proliferation

“…AMPK activation has also been linked with induction of cell cycle arrest and cell death (Vincent et al, 2015). Anti-tumor effects of adenine for colon (Han et al, 2017), cervical (Lai et al, 2019) and hepatic (Su et al, 2020) cancer cells are mediated from adenine-induced cell cycle arrest and AMPK activated. Therefore, the cytotoxic effect of adenine on melanoma cells shown here may be through AMPK activation of adenine in melanoma cells.…”

“…Previous studies showed that adenine is cytotoxic to lymphoblast (Hershfield et al, 1977;Snyder et al, 1978) and has anti-tumor activity for colon (Han et al, 2017), cervical (Lai et al, 2019) and hepatic (Su et al, 2020) cancer cells.…”