Prevalence, incidence and risk factors of tamoxifen-related non-alcoholic fatty liver disease: A systematic review and meta-analysis

Changes in m6A in Steatotic Liver Disease

Fatty liver disease is one of the major causes of morbidity and mortality worldwide. Fatty liver includes non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH), now replaced by a consensus group as metabolic dysfunction-associated steatotic liver disease (MASLD). While excess nutrition and obesity are major contributors to fatty liver, the underlying mechanisms remain largely unknown and therapeutic interventions are limited. Reversible chemical modifications in RNA are newly recognized critical regulators controlling post-transcriptional gene expression. Among these modifications, N6-methyladenosine (m6A) is the most abundant and regulates transcript abundance in fatty liver disease. Modulation of m6A by readers, writers, and erasers (RWE) impacts mRNA processing, translation, nuclear export, localization, and degradation. While many studies focus on m6A RWE expression in human liver pathologies, limitations of technology and bioinformatic methods to detect m6A present challenges in understanding the epitranscriptomic mechanisms driving fatty liver disease progression. In this review, we summarize the RWE of m6A and current methods of detecting m6A in specific genes associated with fatty liver disease.

Mitochondrial alterations in fatty liver diseases

Fatty liver diseases can result from common metabolic diseases, as well as from xenobiotic exposure and excessive alcohol use, all of which have been shown to exert toxic effects on hepatic mitochondrial functionality and dynamics. Invasive or complex methodology limits large-scale investigations of mitochondria in human livers. Nevertheless, abnormal mitochondrial function, such as impaired fatty acid oxidation and oxidative phosphorylation, drives oxidative stress and has been identified as an important feature of human steatohepatitis. On the other hand, hepatic mitochondria can be flexible and adapt to the ambient metabolic condition to prevent triglyceride and lipotoxin accumulation in obesity. Experience from studies on xenobiotics has provided important insights into the regulation of hepatic mitochondria. Increasing awareness of the joint presence of metabolic disease-related (lipotoxic) and alcohol-related liver diseases further highlights the need to better understand their mutual interaction and potentiation in disease progression. Recent clinical studies have assessed the effects of diets or bariatric surgery on hepatic mitochondria, which are also evolving as an interesting therapeutic target in non-alcoholic fatty liver disease. This review summarises the current knowledge on hepatic mitochondria with a focus on fatty liver diseases linked to obesity, type 2 diabetes and xenobiotics.

Tamoxifen induced hepatic steatosis in high-fat feeding rats through SIRT1-Foxo1 suppression and LXR-SREBP1c activation

Background

Clinically, long-term use of tamoxifen (TAM) would lead to fatty liver disease in breast cancer patients, especially obese women. However, the exact mechanism of TAM-induced hepatic steatosis is still unclear. Meanwhile, there is no drug to prevent and treat it.

Aims and Methods

In view of silent information regulator 1 (SIRT1) playing a key role in hepatic lipid metabolism regulation, this study was conducted to investigate whether SIRT1 is a potential therapeutic target for TAM-induced hepatic steatosis. In this study, obese female Wistar rats fed with high-fat diet (HFD) for 15 weeks were given TAM (4, 8 mg/kg, intragastric) for 14 days. In vitro, human hepatocarcinoma cell line HepG2 was used to establish a high-fat model with 50 μM oleic acid and TAM (10 μM) was treated simultaneously for 72 h.

Results

The results showed that TAM was more likely to upregulate the expression of lipid synthetase that caused the increase of lipid content in HepG2 cells and rat liver. The expression of SIRT1 was downregulated both in vitro and in vivo. SIRT1 agonist SRT1720 (15 mg/kg, 30 mg/kg, i.p.) could resist TAM-induced hepatic lipid synthetase overexpression to relieve TAM-induced hepatic steatosis. Meanwhile, the upregulation of p-forkhead box O1 and LXRα induced by TAM was reversed by SRT1720.

Conclusions

These results indicated that TAM-induced hepatic steatosis was based on SIRT1-p-FoxO/LXRα-sterol regulatory element binding protein 1c pathway under HFD condition. SIRT1 agonist might be a potential therapeutic drug to relieve this side effect.

Highlights

Tamoxifen increased lipid synthesis and regulated lipid transport in HFD rat liver.p-FoxO1/LXRα-SREBP1c signaling was upregulated through the inhibition of SIRT1 in tamoxifen-induced hepatic steatosis under HFD condition.SIRT1 agonist SRT1720 could relieve tamoxifen-induced hepatic steatosis.

Fatty Liver in Hormone Receptor-Positive Breast Cancer and Its Impact on Patient's Survival

Purpose

Long-term estrogen inhibition may cause fatty liver disease (non-alcoholic fatty liver disease; NAFLD) among other adverse conditions such as osteoporosis, climacteric symptoms, thromboembolism, dyslipidemia, and metabolic syndrome. The prevalence of NAFLD among breast cancer patients ranges from 2.3%–45.2%. This study aimed to determine the risk factors for newly developed NAFLD among breast cancer patients after hormonal treatment and whether it influences survival outcomes.

Methods

This retrospective study investigated hormone receptor (HR)-positive, human epidermal growth factor receptor 2 (HER2)-negative (HR+/HER2−), nonmetastatic breast cancer patients diagnosed between January 2010 and December 2018. All patients received adjuvant hormonal treatment for at least 6 months. Clinical data on metabolic profile indicators such as body mass index (BMI), waist circumference, serum cholesterol, triglycerides, low-density lipoprotein-cholesterol (LDL-C), high-density lipoprotein-cholesterol (HDL-C), diabetes, and presence of metabolic syndrome (MetS) were collected. In total, 160 eligible patients with complete covariate data and survival follow-up were included.

Results

NAFLD was diagnosed in 35% of patients. There were significant associations of being overweight (BMI ≥ 25 kg/m²), waist circumference > 80 cm, triglycerides ≥ 150 mg/dL, HDL-C ≤ 50 mg/dL, LDL-C < 150 mg/dL, and presence of MetS with the development of NAFLD. However, unlike other factors, MetS and HDL-C were not independently associated with NAFLD. Patients with breast cancer who developed NAFLD had longer disease-free survival (DFS). The median DFS was not reached in the NAFLD group, whereas it was 59.3 (45.6–73.0) months in the non-NAFLD group. No worsening of overall survival was observed in patients with breast cancer and NAFLD.

Conclusion

The development of NAFLD during treatment in patients with HR+/HER2− breast cancer was associated with several independent risk factors: being overweight, waist circumference, triglycerides, and LDL-C. Interestingly, breast cancer patients with NAFLD during treatment had longer DFS than those without NAFLD.

Vitamin D modulates hepatic microRNAs and mitigates tamoxifen-induced steatohepatitis in female rats

Tamoxifen (TAM) is a life-saving and cost-effective drug widely used in the prevention and treatment of breast cancer. However, the adverse effects of tamoxifen can lead to non-adherence and poor patient outcomes. Therefore, exploring novel strategies to improve TAM safety profile is crucial. Given the key role that vitamin D (VD) plays in modulating lipid metabolism and inflammation, in addition to its benefits in reducing risk and progression of breast cancer, we evaluated the protective potential of VD against TAM-induced hepatotoxicity focusing on lipid metabolism and microRNAs (miRNAs) regulation. Female rats were pretreated with VD as cholecalciferol (500 IU/kg/day, po) for 4 weeks before receiving TAM (40 mg/kg/day, po) concurrently with VD during the fifth and sixth weeks. Liver histology, lipid profile and expression of genes, proteins, and miRNAs involved in lipid metabolism and inflammation were examined. TAM-induced steatohepatitis was evidenced by elevated liver triglycerides and cholesterol contents, increased serum miRNA-122 level, and ALT activity, in parallel with accumulation of lipid droplets, focal necrosis, and inflammatory cells infiltration in hepatocytes. Prophylactic use of VD mitigated TAM-induced steatohepatitis by modulating key transcription factors in the liver: PPAR-α, Srebf1, and NF-κB and their downstream genes/proteins Fas, CPT-1A, and TNF-α resulting in reduced hepatic lipids and suppressed pro-inflammatory signaling. Notably, VD pretreatment mitigated TAM-induced alterations in the expression of serum miRNA-122, hepatic miRNA-21, and miRNA-33. The combination therapy of VD and TAM has complementary benefits in terms of safety and not only efficacy and should be further investigated clinically.

NAFLD and NASH in Postmenopausal Women: Implications for Diagnosis and Treatment

Nonalcoholic fatty liver disease (NAFLD) prevalence in women is increasing worldwide. Women of reproductive age have lower rates of NAFLD compared with men; however, this protection is lost following the menopausal transition when NAFLD prevalence in postmenopausal women becomes similar to or surpasses that in age-matched male counterparts. Ongoing epidemiological, clinical, and experimental studies indicate greater NAFLD risk and higher rates of severe hepatic fibrosis in postmenopausal women relative to premenopausal women, and that older women with NAFLD experience greater mortality than men. Investigations involving ovariectomized animal models demonstrate a causal relationship between estrogen deficiency and heightened susceptibility to the development of fatty liver and steatohepatitis, although dietary factors may exacerbate this complex relationship. The accumulated findings suggest that a better understanding of the interplay among menopausal status, metabolic comorbidities, and sex steroids in NAFLD pathogenesis is needed. Further, the mechanisms underlying the difference in NAFLD risk between postmenopausal and premenopausal women remain incompletely understood. The goals of this review are to summarize studies of NAFLD risk in postmenopausal women, discuss results from animal models of estrogen deficiency, and explore the development of NAFD within the context of altered sex hormone profiles resulting from the menopausal transition. Potential implications for the prevention, diagnosis, and treatment of NAFLD in this relatively understudied cohort are also addressed.

Risk of fatty liver after long-term use of tamoxifen in patients with breast cancer

Background

Few studies report the effects of tamoxifen intake and the occurrence of de novo fatty liver and the deterioration of existing fatty liver. The aim of this study was to investigate the effects of tamoxifen on fatty change of liver over time and also the impact of fatty liver on the prognosis of patients with breast cancer.

Methods

This was a single-center, retrospective study of patients who were diagnosed with primary breast cancer from January 2007 to July 2017. 911 consecutive patients were classified into three groups according to treatment method: tamoxifen group, aromatase inhibitor (AI) group, and control group.

Results

Median treatment duration was 49 months (interquartile range, IQR; 32–58) and median observational period was 85 months (IQR; 50–118). Long-term use of tamoxifen significantly aggravated fatty liver status compared to AI or control groups [hazard ratio (HR): 1.598, 95% confidence interval (CI): 1.173–2.177, P = 0.003] after adjusting other factors. When analyzed separately depending on pre-existing fatty liver at baseline, tamoxifen was involved in the development of de novo fatty liver [HR: 1.519, 95% CI: 1.100–2.098, P = 0.011) and had greater effect on fatty liver worsening (HR: 2.103, 95% CI: 1.156–3.826, P = 0.015). However, the progression of fatty liver did not significantly affect the mortality of breast cancer patients.

Conclusions

Tamoxifen had a significant effect on the fatty liver status compared to other treatment modalities in breast cancer patients. Although fatty liver did not affect the prognosis of breast cancer, meticulous attention to cardiovascular disease or other metabolic disease should be paid when used for a long time.