Berberine inhibits tumor growth and increases the sensitivity to sorafenib via targeting energy metabolism in hepatocellular carcinoma

Abstract

Hepatocellular carcinoma (HCC) is the commonest main liver tumor. The prognosis of HCC is poor since its mortality and incidence rates are comparable. As the first authorized drug for the advanced HCC therapy, sorafenib (SORA) exhibits increasing acquired drug resistance which dissatisfies its clinical efficacy. In comparison to normal cells, cancer cells could reprogram metabolic pathways, especially glucose and energy metabolism, to promote their excessive growth and develop chemoresistance. Metabolic rewiring plays a pivotal role in the tumorigenesis, tumor progression, and chemoresistance of cancer. Berberine (BBR), as a naturally occurring alkaloid from Coptis chinensis, has been shown potential anti-tumor and anti-chemoresistance effects against HCC. However, the function of BBR in metabolic regulation during HCC tumorigenesis and SORA chemoresistance has not been defined yet. Firstly, I investigated the inhibitory effects of BBR on HCC from the metabolic perspective. I found that as an alternative energy source, alanine triggered the metabolic rewiring of HCC cells by activating the downstream glucose-alanine cycle and thereby facilitated HCC growth at the nutrient-poor environment. Further overexpression and loss-of-function investigations revealed that glutamic pyruvic transaminase 1 (GPT1) was a vital regulator for alanine-supplemented HCC growth. GPT1 overexpression promoted the glucose-alanine cycle, and thus facilitated the growth and progression of HCC, whereas the inhibition of GPT1 with a common transaminase inhibitor- aminooxyacetate (AOA) highly inhibited alanine-induced HCC growth. The molecular docking and enzymatic activity inhibition assay characterized BBR as the GPT1 inhibitor to suppress HCC growth. The metabolomics analysis demonstrated that BBR induced metabolic reprogramming mainly via mediating glucose-alanine cycle in HCC from the metabolic perspective. Further mechanistic studies revealed that BBR-induced metabolic rewiring of alanine-supplemented HCC cells through GPT1 inhibition retarded adenosine triphosphate (ATP) production and thereby inhibited HCC growth. Next, the in vitro and in vivo synergistic effects of SORA and BBR on HCC were also investigated from the metabolic perspective. The results indicated that BBR specifically potentiated the repressive effects of SORA on HCC cells. The transcriptomic analysis suggested that BBR sensitized HCC cells to SORA by regulating energy metabolic pathways. In detail, SORA and BBR synergistically suppressed the energy metabolism of HCC cells by inhibiting ATP and lactate production, decreasing extracellular acidification rate (ECAR) and oxygen consumption rate (OCR) as well as attenuating the expression of energy metabolism related proteins. The synergistic effects of SORA and BBR on energy metabolism resulted in growth inhibition of HCC cells via B-cell lymphoma (BCL) signaling, which were reversed by the addition of glucose. Further mechanistic studies revealed that hypoxia-inducible factor-1alpha (HIF-1α) was responsible for the sensitization of HCC to SORA by BBR, which was neutralized by the restoration of HIF-1α with cobalt (II) chloride (CoCl2). At last, the synergistic effects of SORA and BBR in the orthotopic HCC implantation murine model was also observed. In conclusion, the demonstration of BBR-mediated metabolic rewiring to suppress HCC growth and increase the sensitivity to SORA in HCC would help to the development of Chinese medicine as neoadjuvant therapeutics and chemosensitizer for HCC therapy.