HCC can be considered as a prototype of inflammation-derived disease caused by chronic liver injury [20, 21], and brought us a huge social and health burden. In the recent years, the immunotherapy has revolutionized the management of HCC, and improve the overall survival of HCC patients in comparison to traditional sorafenib singly, which lead to the approval of this regimen by FDA [22]. However, the overall survival of five years in HCC patients is still poor. Recently, the common immunotherapy is immune-checkpoint inhibitors, and it can obviously improve HCC, and even combination therapy has achieved the satisfactory curative effect [23]. Despite of these significant development in the HCC treatment, it is still necessary for identifying the more efficient drug targets for further improving the HCC treatment.
Increasing evidences revealed that m6A RNA methylation, regulated by 23 m6A regulators, participated in the pathogenesis different types of human malignancies including HCC [21]. On the other hand, the role of m6A regulators in HCC has also been determined [24]. For example, FTO feedback loop, regulated by CircGPR137B/miR-4739 axis was showed to significantly suppresses the tumorigenesis and metastasis of HCC [25]. METTL3, also regulates gene expression through a m6A-dependent manner and is was confirmed to contribute to the carcinogenesis, tumor progression, and drug resistance in HCC [26]. METTL16 has been reported to promote HCC progression through directly inhibiting the expression of RAB11B-AS1 by an m6A-dependent manner [27]. PA2G4 promoted the metastasis of HCC by stabilizing FYN mRNA in a YTHDF2-dependent manner [28]. In addition, the m6A-related long noncoding RNAs (lncRNAs) have also been demonstrated to affect the development and progression of HCC, and even the prognosis of HCC patients [29, 30]. Recently, more researches have paid the attentions on the role of m6A regulator on immune microenvironment in human cancer. However, little is known about its impact on the immune microenvironment in HCC. In this study, we found that most of m6A regulators showed significantly expression difference between HCC samples and heathy controls. The infiltration ratio of some immune cells and immune functions were significantly different between the HCC group and the healthy group. M6A regulator expression could divide the HCC samples into two distinct biologically subtypes. Subtype-2 mediated active immune responses and subtype 1 led to mild immune responses in HCC. Our findings revealed the potential role of m6A regulator in tumor immune microenvironment in HCC, and contributed to our understanding on HCC progression.
Then we identified top 10 DEGs that influenced by m6A regulator, and found that 8 of the 10 hub genes could be matched to the corresponding drugs, among which the ESR1 gene corresponded to the most drugs. These findings suggested that ESR1 might be a potential drug target for treating HCC. The important role of ESR1 in HCC has also been partially studied. Zhang et al., found that ESR1 could inhibit the occurrence and development of HCC by regulating the gene MMAA, an obesity and metabolism differential gene [31]. In addition, Hu et al., revealed that ESR1 also could promote HCC progression via transcriptionally regulating HS1BP3 [32]. These evidences all suggested that ESR1 was a potential therapeutic target in HCC. Our findings found that raloxifene and bexarotene could target ESR1, as the candidate drugs for treating HCC. Our study contributed us to understand the important regulatory role of m6A regulator in HCC progression, and even suggested two potential treatment drugs targeting ESR1, providing some guidance for clinical treatment in HCC.
In conclusion, our study identified two distinct patterns of RNA modification mediated by 23 m6A modulators, and screened out a series of patterns related hub genes associated with potential treatment drugs. Moreover, our findings provided the novel treatment strategies and even candidate drugs in HCC. However, the effect of raloxifene and bexarotene in HCC, as well as the potential mechanisms between these two drugs and ESR1 needed to be further investigated in the subsequent experiments.