Therapeutic Efficacy of Vitamin D in Experimental c-MET-β-Catenin-Driven Hepatocellular Cancer

The MET Family of Receptor Tyrosine Kinases Promotes a Shift to Pro-Tumor Metabolism

The development and growth of cancer is fundamentally dependent on pro-tumor changes in metabolism. Cancer cells generally shift away from oxidative phosphorylation as the primary source of energy and rely more heavily on glycolysis. Receptor tyrosine kinases (RTKs) are a type of receptor that is implicated in this shift to pro-tumor metabolism. RTKs are important drivers of cancer growth and metastasis. One such family of RTKs is the MET family, which consists of MET and RON (MST1R). The overexpression of either MET or RON has been associated with worse cancer patient prognosis in a variety of tumor types. Both MET and RON signaling promote increased glycolysis by upregulating the expression of key glycolytic enzymes via increased MYC transcription factor activity. Additionally, both MET and RON signaling promote increased cholesterol biosynthesis downstream of glycolysis by upregulating the expression of SREBP2-induced cholesterol biosynthesis enzymes via CTTNB1. These changes in metabolism, driven by RTK activity, provide potential targets in limiting tumor growth and metastasis via pharmacological inhibition or modifications in diet. This review summarizes pro-tumor changes in metabolism driven by the MET family of RTKs. In doing so, we will offer our unique perspective on metabolic pathways that drive worse patient prognosis and provide suggestions for future study.

The Influence of Diet and Its Components on the Development and Prevention of Hepatocellular Carcinoma (HCC)

Hepatocellular carcinoma (HCC) is diagnosed annually in nearly a million people worldwide, with approximately half of them being diagnosed at an advanced stage of the disease. Non-infectious risk factors for the development of HCC include an unbalanced lifestyle, including poor dietary choices characterized by a low intake of antioxidants, such as vitamins E and C, selenium, and polyphenols, as well as an excessive consumption of energy and harmful substances. Repeated bad dietary choices that contribute to an unbalanced lifestyle lead to the accumulation of fatty substances in the liver and to it entering an inflammatory state, which, without intervention, results in cirrhosis, the main cause of HCC. This review of the English language literature aims to present the food components that, when included in the daily diet, reduce the risk of developing HCC, as well as identifying foods that may have a carcinogenic effect on liver cells.

Role of Vitamin D in Liver Disease and Complications of Advanced Chronic Liver Disease

Vitamin D is a crucial nutrient with many pleiotropic effects on health and various chronic diseases. The purpose of this review is to provide a detailed report on the pathophysiological mechanisms underlying vitamin D deficiency in patients with chronic liver disease, addressing the different liver etiologies and the condition of advanced chronic liver disease (cirrhosis) with related complications. To date, patients with liver disease, regardless of underlying etiology, have been shown to have reduced levels of vitamin D. There is also evidence of the predictive role of vitamin D values in complications and progression of advanced disease. However, specific indications of vitamin D supplementation are not conclusive concerning what is already recommended in the general population. Future studies should make an effort to unify and validate the role of vitamin D supplementation in chronic liver disease.

Vitamin D3 supplementation alleviates chemically-induced cirrhosis-associated hepatocarcinogenesis

Vitamin D₃ (VD₃) deficiency has been associated with increased risk for cirrhosis and hepatocellular carcinoma, a highly incident malignant neoplasia worldwide. On the other hand, VD₃ supplementation has shown some beneficial effects in clinical studies and rodent models of chronic liver disease. However, preventive effects of dietary VD₃ supplementation in cirrhosis-associated hepatocarcinogenesis is still unknow. To investigate this purpose, male Wistar rats submitted to a combined diethylnitrosamine- and thioacetamide-induced model were concomitantly supplemented with VD₃ (5,000 and 10,000 IU/kg diet) for 25 weeks. Liver samples were collected for histological, biochemical and molecular analysis. Serum samples were used to measure 25-hydroxyvitamin D [25(OH)D] and alanine aminotransferase levels. Both VD₃ interventions decreased hepatic collagen deposition and pro-inflammatory p65 protein levels, while increased hepatic antioxidant catalase and glutathione peroxidase activities and serum 25(OH)D, without a clear dose-response effect. Nonetheless, only the highest concentration of VD₃ increased hepatic protein levels of VD receptor, while decreased the number of large preneoplastic glutathione-S-transferase- (>0.5 mm²) and keratin 8/18-positive lesions, as well the multiplicity of hepatocellular adenomas. Moreover, this intervention increased hepatic antioxidant Nrf2 protein levels and glutathione-S-transferase activity. In summary, dietary VD₃ supplementation - in special the highest intervention - showed antifibrotic and antineoplastic properties in chemically-induced cirrhosis-associated hepatocarcinogenesis. The positive modulation of Nrf2 antioxidant axis may be mechanistically involved with these beneficial effects, and may guide future clinical studies.

Wnt and Vitamin D at the Crossroads in Solid Cancer

Simple Summary

The Wnt/β-catenin signaling pathway is aberrantly activated in most colorectal cancers and less frequently in a variety of other solid neoplasias. Many epidemiological and experimental studies and some clinical trials suggest an anticancer action of vitamin D, mainly against colorectal cancer. The aim of this review was to analyze the literature supporting the interference of Wnt/β-catenin signaling by the active vitamin D metabolite 1α,25-dihydroxyvitamin D₃. We discuss the molecular mechanisms of this antagonism in colorectal cancer and other cancer types. Additionally, we summarize the available data indicating a reciprocal inhibition of vitamin D action by the activated Wnt/β-catenin pathway. Thus, a complex mutual antagonism between Wnt/β-catenin signaling and the vitamin D system seems to be at the root of many solid cancers.

Abstract

Abnormal activation of the Wnt/β-catenin pathway is common in many types of solid cancers. Likewise, a large proportion of cancer patients have vitamin D deficiency. In line with these observations, Wnt/β-catenin signaling and 1α,25-dihydroxyvitamin D₃ (1,25(OH)₂D₃), the active vitamin D metabolite, usually have opposite effects on cancer cell proliferation and phenotype. In recent years, an increasing number of studies performed in a variety of cancer types have revealed a complex crosstalk between Wnt/β-catenin signaling and 1,25(OH)₂D₃. Here we review the mechanisms by which 1,25(OH)₂D₃ inhibits Wnt/β-catenin signaling and, conversely, how the activated Wnt/β-catenin pathway may abrogate vitamin D action. The available data suggest that interaction between Wnt/β-catenin signaling and the vitamin D system is at the crossroads in solid cancers and may have therapeutic applications.

Extracellular Vesicle-Based Therapeutic Targeting of β-Catenin to Modulate Anticancer Immune Responses in Hepatocellular Cancer

Hepatocellular carcinoma (HCC) is a leading cause of cancer-related death worldwide. Although HCC can respond to immune checkpoint inhibitors, such as monoclonal antibodies against programmed death 1 (PD-1), many patients fail to respond or develop secondary resistance. Activation of Wnt/β-catenin signaling can contribute to immune evasion. Mutations in β-catenin are among the most frequent mutations associated with HCC. Thus, our aim was to directly target β-catenin to enhance the therapeutic response to immune checkpoint inhibition. A synthetic transgenic mouse model of experimental HCC induced by tyrosine-protein kinase Met/β-catenin expression and extracellular vesicles (EVs) as a therapeutic delivery agent was used to evaluate the efficacy of directly targeting β-catenin on the response to anti-PD-1. These studies showed that (1) oncogenic β-catenin could be therapeutically targeted using a biological nanoparticle-based delivery approach, (2) targeting β-catenin using small interfering RNA (siRNA) delivered within EVs can reduce tumor growth, and (3) the therapeutic response to anti-PD-1 can be enhanced by concomitantly targeting β-catenin using therapeutic EVs. These preclinical studies establish the efficacy of the use of biological nanoparticles as an endogenous delivery vehicle for therapeutic RNA delivery and support the use of therapeutic strategies targeting tumor-intrinsic β-catenin as an adjunct to anti-PD-1-based therapy. Conclusion: Combination therapy with anti-PD-1 and β-catenin siRNA delivered using biological nanoparticles provides an effective strategy for the treatment of HCC. This strategy could be further exploited into targeted approaches for immune potentiation by countering oncogene-mediated resistance to immunotherapies.