Liver cancer is a significant public health concern, ranking sixth in most diagnosed cancers and third in cancer-related deaths globally [1][2]. Liver cancer, particularly hepatocellular carcinoma (HCC), has shown a rise in both the number of new cases and deaths worldwide [3]. HCC is the predominant form of primary liver cancer and is the third leading cause of cancer-related deaths in Burkina Faso [1][4]. Based on WHO projections, there will be a 58% increase in new cases by 2040, with 1,400,000 new cases and 1,000,000 deaths expected in 2030 [5]. The primary etiological factors for HCC vary depending on the geographical location and the underlying risk factors for liver diseases. For example, in areas with high prevalence rates of hepatitis B virus (HBV) infection, such as in Asia and sub-Saharan Africa, chronic HBV infection is the leading cause of HCC [5][6]. In contrast, hepatitis C virus (HCV) infection is the primary etiological factor for HCC in many developed countries, including the United States, Japan, and Western Europe [7]. In addition to viral infections, other factors such as alcohol consumption, non-alcoholic fatty liver disease (NAFLD), and exposure to environmental toxins also contribute to the development of HCC [8]. Furthermore, there are disparities in access to healthcare and treatment options for HCC, which can lead to differences in survival rates across populations. Addressing these disparities in HCC etiology, incidence, and mortality requires a comprehensive understanding of the underlying risk factors and effective public health interventions to prevent and manage the liver disease.

In addition to these many risk factors, changes such as mutations within the human genome have been identified as integral to the development of HCC. Among these mutations, mutations in the tumor protein P53 (TP53), β-catenin (CTNNB1), and telomerase reverse transcriptase (TERT) genes are frequently found in HCC and have been studied extensively in relation to the development and progression of the disease [9][10].

Telomerase activity is weakly absent in somatic cells, although strongly expressed in embryonic and stem cells [9]. TERT plays a central role in cell immortality and tumorigenesis by maintaining telomere homeostasis and integrity and TERT promoter mutations are found in about 50% of HCC [11]. Two common single-nucleotide polymorphisms (SNPs), C228T and C250T, have been identified in the promoter of TERT. They are known to create potential binding sites for transcription factors and increase promoter activity, ultimately leading to TERT transcription and cell immortality [12]. These SNPs are located at two hotspots, corresponding to positions 124 (C228T) and (C250A)146 bp upstream of the TERT translation start site. The mutant TERT promoter activity requires the “de novo” ETS motif, and ETS candidate factors may regulate TERT expression directly through the C228T and C250T mutations [10][11].

The association of TERT promoter mutations with HCC in African patients with chronic HBV infection is not well studied, as most of the research has been conducted in East Asia and Europe. However, some studies have suggested that TERT promoter mutations are also prevalent in HCC cases in Africa. For example, a study conducted in South Africa found that TERT promoter mutations were present in 53.3% of HCC cases, and the prevalence of these mutations was higher in cases with chronic HBV infection [13].

The present study aims to investigate the prevalence and functional significance of TERT promoter mutations in HCC patients from Burkina Faso, where chronic HBV infection is a major risk factor for the disease with a prevalence of 14,47% [14]. By understanding how these mutations contribute to HCC development and progression in African populations, this investigation may provide important insights into the molecular mechanisms. These findings could help guide more effective prevention and treatment strategies.

This study provides new insights into TERT promoter mutations in a population samples from Burkina Faso, which have not been extensively studied in the literature. The results of the study demonstrate the presence of multiple mutations in four groups of patients, some of which have not been previously reported. Despite the small sample size, the findings are an important contribution to the understanding of HCC in this region and emphasize the need for continued investigation into the molecular abnormalities associated with the disease.

Our study showed a relatively young age of onset, with a mean age of approximately 42,29 years, which is in contrast to the typical occurrence of HCC in elderly (~55 years) individuals reported in developed countries [15][16]. However, this finding is consistent with the demographic profile of Burkina Faso, where nearly 80% of the population is under 35 years of age, according to the National Institute of Statistics and Demography [17]. To effectively prevent and treat HCC in Burkina Faso, it is crucial to understand the unique characteristics of this population. As etiologic factors leading to HCC can vary between countries, further investigation into the specific risk factors for HCC in Burkina Faso is needed. Moreover, the higher incidence of HCC in men globally may indicate a potential role for gender-specific risk factors, emphasizing the need for gender-specific research in this area. Additionally, environmental factors such as high incidence of viral infections (e.g., hepatitis B and C), alcohol consumption, and exposure to aflatoxins can also contribute to the development of HCC. These factors can further exacerbate the accumulation of genetic and epigenetic changes in the liver cells, increasing the risk of developing HCC [18]. Therefore, genetic profiling and understanding of the molecular mechanisms underlying HCC development remain crucial for developing effective prevention and treatment strategies.

In this respect, previous studies have already characterized the main risk factor in Burkina Faso, the hepatitis B virus, as well as some genetic characteristics of infected individuals. Genotype E of the hepatitis B virus has been identified as the main healing variant [19]. Various studies have also looked at the role of certain genes in the progression of infection. Compaoré et al., showed that the APOBEC3 gene polymorphism rs35228531 had a protective effect in HBV/HIV coinfection [20]; KIR3DL1, KIR3DL2, KIR2DS1 also had a protective effect against chronic hepatitis B infection [21].

The G228T and G250T mutations in the TERT promoter are known to be mutually exclusive, meaning that they tend to occur independently of each other [22][23]. The G228T mutation is more common than the G250T mutation, and it has been found to be associated with HCC (31.4% [23], 65.4% [16]) and other types of cancer [24]. Recent research suggests that both mutations may be associated with rare cancer cases, but more studies are needed to confirm these findings.

Our study identified the G228T mutation in the promoter region of TERT as a common mutation in HCC cases (18.18%), HCC with cirrhosis (50%), cirrhosis only (15.38%), and indeterminate cases (100%). In addition to G228T and G250T, we also identified other previously unreported SNPs in the TERT promoter in our cohort. Notably, our study found the G228T mutation to be the only TERT promoter mutation present in our cohort, which differs from previous studies that have reported both G228T and C250T mutations. This may suggest a regional or population difference in the prevalence of these mutations. However, it is important to note that our sample size was relatively small and further studies are needed to confirm these findings.

Our luciferase experiments provided additional support for the importance of the G>A/T transition in TERT gene activation, as this mutation is believed to create a new binding site for ETS transcription factors, which in turn activated TERT transcription and telomerase. Our study confirms the findings of a previous study on glioblastoma [10], which showed that mutations induced at specific positions did not increase promoter activity, highlighting the necessity of the G>A/T transition for TERT gene activation. Studies have also suggested that GA-binding proteins (GABPA and GABPB1), members of the ETS family of transcription factors, are specifically recruited to the TERT mutant promoter but not to the wild-type promoter in cancer cells, thereby activating TERT transcription and telomerase [25][26].

While the G228T mutation in the TERT promoter region is a crucial factor in activating TERT transcription and telomerase, it is not the only factor involved in telomere maintenance and HCC development. TERT promoter methylation, which can affect the binding of transcription factors, has been reported to be associated with TERT expression and telomere maintenance in HCC. Moreover, genomic structural rearrangements and TERT copy number alterations have also been implicated in HCC development and telomere maintenance [27]. Finally, some HCCs can maintain telomere length through an alternative mechanism known as alternative lengthening of telomeres (ALT) that involves homologous recombination-mediated telomere synthesis [27]. Thus, a comprehensive understanding of the mechanisms of telomere maintenance in HCC requires considering multiple factors, including the G228T mutation, TERT promoter methylation, genomic structural rearrangements, TERT copy number, and alternative telomere lengthening.

In summary, our study identified new TERT promoter mutations in HCC patients from Burkina Faso and validated the function of some of these mutations, particularly G228A/T, which creates a novel binding site for the transcription factor ETS. Our findings support the role of TERT promoter mutations in the development of HCC and cirrhosis in this population. However, further research is needed to confirm our results in larger HCC samples and to investigate the association of TERT promoter mutations with other tumor-associated mutations, such as TP53 and CTNNB1.

The authors acknowledge resources and support from the Biodesign Institute core facilities at Arizona State University.