Long non-coding RNA in the regulation of cell death in hepatocellular carcinoma

Abstract

Hepatocellular carcinoma (HCC) is the predominant form of primary liver cancer, accounting for 90% of all cases. Currently, early diagnosis of HCC can be achieved through serum alpha-fetoprotein detection, B-ultrasound, and computed tomography scanning; however, their specificity and sensitivity are suboptimal. Despite significant advancements in HCC biomarker detection, the prognosis for patients with HCC remains unfavorable due to tumor heterogeneity and limited understanding of its pathogenesis. Therefore, it is crucial to explore more sensitive HCC biomarkers for improved diagnosis, monitoring, and management of the disease. Long non-coding RNA (lncRNA) serves as an auxiliary carrier of genetic information and also plays diverse intricate regulatory roles that greatly contribute to genome complexity. Moreover, investigating gene expression regulation networks from the perspective of lncRNA may provide insights into the diagnosis and prognosis of HCC. We searched the PubMed database for literature, comprehensively classified regulated cell death mechanisms and systematically reviewed research progress on lncRNA-mediated cell death pathways in HCC cells. Furthermore, we prospectively summarize its potential implications in diagnosing and treating HCC.

Key Words: Hepatocellular carcinoma; Long non-coding RNA; Necrosis; Apoptosis; Iron death; Autophagy; Cell death

Core Tip: The molecular mechanisms underlying hepatocellular carcinoma (HCC) development remain challenging to fully elucidate. The advent of high-throughput sequencing technologies has revealed that long non-coding RNAs (lncRNAs) play a pivotal role in gene regulation, contributing to cell proliferation, inhibiting apoptosis, promoting invasion and metastasis, and modulating metabolic processes. Dysregulation of lncRNAs is intricately linked to the progression of HCC, indicating their potential as prognostic markers and therapeutic targets. In this review, we systematically examine the research progress on lncRNA-mediated regulation of HCC cell death and discuss its potential therapeutic applications.

INTRODUCTION

Hepatocellular carcinoma (HCC) ranks as the sixth most prevalent cancer globally and is responsible for the fourth highest number of cancer-related deaths. The 5-year survival rate for liver cancer patients worldwide stands at a mere 18%, with even lower rates observed in many Asian countries[1,2] Consequently, this imposes a substantial burden on both families and society. Common treatment modalities for HCC encompass hepatectomy, liver transplantation, ablative therapy, transarterial chemoembolization, radiation therapy, systematic anti-tumor therapy, and other approaches. Hepatectomy represents the primary curative option for early-stage liver cancer, while radiofrequency ablation and transcatheter chemoembolization serve as standard treatments in the disseminated stage of the disease[3,4]. However, due to the intricate nature and heterogeneity of this condition coupled with its often asymptomatic or atypical clinical presentation among patients with liver cancer, a significant proportion of patients lose their eligibility for surgery due to local progression upon diagnosis. However, remarkable progress has recently been made in advanced liver cancer treatment owing to the emergence of various targeted therapies and immunotherapeutic agents[5].

Since its approval by the United States Food and Drug Administration in 2007, the multi-targeted tyrosine kinase inhibitor sorafenib has transformed the therapeutic landscape for advanced HCC. For nearly a decade, sorafenib remained the sole systemic therapy option for this condition. However, clinical studies of IMbrave150 have demonstrated that the combination of atezolizumab and bevacizumab yields superior outcomes compared to sorafenib. Atezolizumab extends progression-free survival by 2-6 mo and reduces the risk of cancer progression by 41% compared to sorafenib alone. As a result, the combination of bevacizumab and atezolizumab has emerged as a current standard first-line treatment[6]. Immune checkpoint inhibitors (ICIs) are currently considered mainstream immunotherapy options for liver cancer[7]. In this therapeutic approach, immunotherapy primarily targets the immune microenvironment surrounding tumors. By employing ICIs, interactions between tumor cells and immune cell surfaces are obstructed while signal transduction is inhibited, consequently activating immune cell activity. This leads to autoreactive killing of cancer cells and tumor tissues, thereby achieving effective tumor eradication[8,9].

However, targeted therapy primarily focuses on aberrant genes within the body, such as EGFR gene, ALK gene, ROS-1 gene, etc. Targeted therapy directly acts on these targets and inhibits their pathways when abnormal mutations occur in the genes. This effectively restricts tumor growth and achieves anti-tumor objectives[10,11]. Thus, a thorough understanding of the tumor immune microenvironment and the identification of valuable biomarkers are essential for advancing cancer therapy, particularly immunotherapy[12-14]. Consequently, identifying biomarkers associated with the immune microenvironment in HCC patients holds significant importance. As a biomarker, long non-coding RNA (lncRNA) exerts intricate and precise regulatory functions in development and gene expression through aberrant sequence and spatial structure, abnormal expression levels, as well as anomalous interactions with binding proteins[15]. For instance, it participates in the regulation of cell cycle progression, apoptosis, cell differentiation, and other vital biological processes[16,17]. Moreover, lncRNAs can modulate molecules associated with HCC metastasis at both the transcriptional and post-transcriptional levels, while also serving as potential diagnostic indicators and therapeutic targets for HCC patients[18]. According to the rate of cellular demise and whether drugs or genes may influence this process, cell death is categorized into two types: Accidental cell death (ACD) and regulated cell death (RCD). ACD occurs due to biological processes whereas RCD is mediated by signal transduction pathways with clear mechanisms of action[19]. Based on distinct morphological, biochemical, immunological, and genetic characteristics, RCDs are further classified into apoptotic and non-apoptotic subtypes[20,21]. Non-apoptotic RCD encompasses autophagy, iron-induced death (ferroptosis), pyroptosis, and necrosis. Cuproptosis, a recently identified form of programmed cell death, has garnered significant attention and sparked extensive research and discussion in the scientific community. Notably, lncRNA closely associates with the regulatory mechanisms underlying HCC cell death.

To elucidate the mechanism of lncRNA-mediated regulatory cell death in HCC cells, we conducted a literature search in the PubMed database. We used the keywords "HCC", "lncRNA", "necroptosis", "apoptosis", "ferroptosis", "pyroptosis", "autophagy", and "cuproptosis", restricting our search to articles published within the past five years.

By elucidating the mechanisms underlying necrosis, apoptosis, ferroptosis, and autophagy in HCC cells, as well as exploring the involvement of lncRNAs in RCD processes, this study highlights the pivotal regulatory role exerted by lncRNAs in HCC cells (Table 1). Furthermore, it delves into the potential utility of lncRNAs as biomarkers and discusses their prospective diagnostic and therapeutic applications in HCC.

Table 1 Abnormal long non-coding RNA studies associated with hepatocellular carcinoma cell death.

Type	Ref.	Year	Findings
Necroptosis	Peng et al[54]	2022	Ten candidate lncRNAs were obtained, from which a prognostic risk model was constructed. The patients with high-risk scores have lower survival rates
	Chen et al[56]	2022	A 6-lncRNA prediction models have good prognostic value for liver cancer, and are worthy of clinical application
	Wang et al[57]	2022	A model containing four necrotic apoptoses-associated lncRNAs was constructed. The OS of low-risk patients is significantly longer than that of high-risk patients
	Chen et al[58]	2024	A positive correlation was observed between the five necrosis-associated lncRNA and the malignant phenotypes of HCC
Apoptosis	Hussain et al[70]	2023	NEAT1 has the ability to inhibit the proliferation, migration and invasion of cancer cells in HCC and promote apoptosis
	Yao et al[71]	2021	LncRNA CASC9 promotes proliferation, migration and inhibits apoptosis of hepatocellular carcinoma cells by down-regulating miR-424-5p
	Cai et al[72]	2021	LncRNA AIRN influences the proliferation and apoptosis of hepatocellular carcinoma cells by regulating STAT1 ubiquitination
	Fei et al[73]	2020	LncRNA ST8SIA6-AS1 promotes hepatocellular carcinoma cell proliferation and resistance to apoptosis by targeting miR-4656/HDAC11 axis
Ferroptosis	Xu et al[83]	2021	A nine-lncRNA-based signature was identified as the ferroptosis-related prognostic model for HCC, independent of multiple clinicopathological parameters
	Zhang et al[84]	2022	LncRNA HEPFAL accelerates ferroptosis in hepatocellular carcinoma by regulating SLC7A11 ubiquitination
Pyroptosis	Wu et al[93]	2023	These prognosis-related lncRNAs, miRNAs, and PRGs formed eleven lncRNA-miRNA-mRNA regulatory axes
Autophagy	Braconi et al[101]	2011	The resistance of HCC to lenvatinib was influenced by the regulatory axis of HOTAIRM1-miR-34a-Beclin-1
Cuproptosis	Li et al[108]	2023	The expression of copper poisoning gene CDKN2A was closely positively associated with lncRNA DDX 11-AS 1

lncRNA: Long non-coding RNA; HCC: Hepatocellular carcinoma; OS: Overall survival.

LNCRNA

Extensive investigations into the human transcriptome have revealed that protein-coding sequences constitute only a minor fraction of the overall transcriptional output[22-24]. The most abundant type of RNA is lncRNA[25], which are characterized by a length exceeding 200 nucleotides and predominantly lack the capacity to encode or translate proteins[26]. The structure of lncRNAs is intricate and varied, encompassing linear, circular, Y-shaped, U-shaped, and other configurations. Moreover, lncRNAs tend to fold into complex secondary and tertiary structures, undergo modifications such as methylation and acetylation, interact with proteins, DNA, and other RNAs, thereby modulating the activities of multi-protein complexes and DNA targets[27].

Moreover, lncRNAs exhibit highly cell type-specific expression patterns[28,29]. Notably, the total number of lncRNAs surpasses that of protein-coding genes by approximately 4.5-fold[30]. Initially regarded as transcriptional by-products of RNA polymerase II with no discernible biological function due to their nuclear or cytoplasmic localization and absence of protein coding potential[31], recent studies have revealed that lncRNAs can act as competing endogenous RNAs (ceRNAs) capable of sequestering miRNA molecules, thereby modulating miRNA-mediated gene regulation through sponge-like mechanisms and consequently influencing cellular physiology[32]. LncRNAs function as molecular signals to modulate various signaling pathways, including p53, AKT, and Notch, as well as epigenetic regulation, DNA damage responses, and a wide range of biological processes such as tumor proliferation, metabolism, apoptosis, aerobic glycolysis, and microRNA regulation. These functions establish lncRNAs as critical participants in cancer development[33-35]. Moreover, lncRNAs can interact with chromatin-modifying enzymes, guiding them to specific genomic loci to regulate gene expression, and also serve as scaffolding molecules to facilitate the formation of protein complexes[36].

Despite their dominance in the transcriptome, the functions of lncRNAs have remained largely unexplored. To date, only a limited number of studies have investigated their mechanisms, and research on lncRNA transmission mechanisms in HCC is particularly inadequate. Numerous international lncRNA databases with variations in species information, function, data classification, and sample reference have been established[37]. Currently, two highly recognized lncRNA databases are lncATLAS and LncRBase[38,39]. To accelerate lncRNA research, Montero et al[40] developed a genome-wide screening platform utilizing CasRX, which facilitates high-throughput mapping and integration of molecular and phenotypic data across various cancers, thereby enabling the inference of lncRNA functions. Extensive investigations into the role of lncRNAs in cancer development have revealed their potential as prognostic indicators, therapeutic targets, and diagnostic tools (Figure 1). Consequently, it is evident that lncRNAs play a crucial role in the growth dynamics, metastasis process, and treatment resistance of cancer cells[41].

Figure 1 Effect of aberrantly expressed long non-coding RNAs on cell death in different modes. A: H19 promotes the phosphorylation of MLKL by RIPK 3 through the miR-675 pathway, and MLKL forms a complex and translocates to the plasma membrane, ultimately leading to necroptosis; B: SNHG 11 binds miR-184 and targets AGO2; Caspase 3 expression increases and promotes apoptosis; C: HEPFAl promotes ferroptosis by modifying SLC7A11 ubiquitination; D: SNHG7 inhibits NLRP3-dependent pyroptosis by targeting the miR-34a/SIRT1 axis in liver cancer; E: NBR2 inhibits autophagy-induced cell proliferation through the ERK and JNK pathways; F: CDKN2A involved in the MAPK signaling pathway. LncRNAs: Long non-coding RNA.

Numerous studies have demonstrated a strong correlation between aberrant expression or functionality of lncRNA and the development of various human diseases, including cancer and degenerative neurological disorders, which pose significant threats to human health[42-45]. Specifically, lncRNAs display aberrant sequence and spatial structures, deregulated expression levels, and atypical interactions with binding proteins. In the context of cancer, lncRNAs exert diverse functions through their interactions with biomolecules, chromatin remodeling processes, transcriptional regulation mechanisms, and post-transcriptional modifications[45-49].

LNCRNA IN HCC

Compared with other cancers, the mechanisms involving lncRNAs in HCC exhibit distinct characteristics. These unique features are primarily attributed to the specific biological properties of the liver, the etiology of HCC, and the tumor microenvironment. For instance, nonalcoholic steatohepatitis (NASH) and viral hepatitis are established risk factors for HCC. NASH is frequently associated with liver fibrosis, obesity, and metabolic syndrome. The lncRNA H19 influences liver fibrosis in NASH by acting as a ceRNA that sequesters miRNAs, thereby modulating the expression of genes involved in fibrosis[50]. Additionally, the lncRNA MALAT1 enhances hepatic steatosis and insulin resistance by stabilizing the nuclear SREBP-1c protein[51]. Consequently, it is imperative to investigate the role of lncRNAs in HCC progression.

LncRNAs regulate HCC cells through multiple mechanisms. Firstly, lncRNAs can bind to DNA, reshaping chromatin structure and inducing epigenetic modifications, thereby modulating the expression of target genes. Secondly, lncRNAs function as molecular sponges by interacting with mRNAs or miRNAs, thus regulating mRNA stability and translation, as well as the binding of miRNAs to their targets. Thirdly, lncRNAs can bind to proteins, influencing protein conformation and activity. Additionally, some lncRNAs contain small open reading frames, which encode peptides with biological functions. These four mechanisms are the primary ways through which lncRNAs regulate HCC cells (Figure 2).

Figure 2 Functional mechanisms of long non-coding RNA in hepatocellular carcinoma. A: UHRF1 drives hepatocellular carcinoma by inducing global DNA hypomethylation; B: Long non-coding RNAs (lncRNAs) bind to mRNAs and miRNAs to regulate their stability, thereby regulating gene expression; C: LncRNAs interact with proteins to regulate their stability or facilitate the formation of protein complex; D: Several lncRNAs hold the potential to encode small peptides, through which they exhibit their biological functions. lncRNAs: Long non-coding RNA.

Necroptosis

In recent years, programmed cell death has garnered significant attention in the field of cell death research. Necroptosis, a regulated form of cytolytic death rather than an accidental occurrence[52], plays a pivotal role in the regulation of tumorigenesis, cancer metastasis, and cancer immunity[53]. To investigate the prognostic value of necrosis-associated lncRNAs in HCC, Peng et al[54] constructed a prognostic model based on The Cancer Genome Atlas (TCGA) public database to validate the role of necrosis-associated lncRNAs in HCC. Through single-factor Cox regression analysis among 779 genes, they identified 58 LncRNAs (PRlncRNAs) associated with necrosis and further screened collinear factors using Lasso-Cox method. Ten candidate lncRNAs (AL031985.3, SREBF2-AS1, ZFPM2-AS1, KDM4A-AS1, AC026412.3, AC145207.5, DUXAP8, LINC01224, AC099850.4, MKLN1-AS) were selected accordingly. Subsequently, a prognostic risk model was established[54]. The roles of AL031985.3 and AC145207.5 in glycolytic-related prognostic models of liver cancer have been demonstrated[55]. However, it is important to note that the reliability of these findings should be further validated using other databases. A novel prognostic model incorporating six necrosis-associated lncRNAs (AL606489.1, NRAV, LINC02870, DUXAP8, "ZFPM2-AS1", AL031985.3) exhibits promising potential for accurately predicting the prognosis of HCC and warrants clinical application[56]. Another model comprising four necrotic lncRNAs (POLH-AS1, DUXAP8, AC131009.1, and TMCC1-AS1) demonstrates significantly prolonged overall survival in low-risk patients compared to high-risk patients[57]. Recent studies[58] have demonstrated that five necrosis-related lncRNAs (ZFPM2-AS1, AC099850.3, BACE1-AS, KDM4A-AS1, and MKLN1-AS) are positively correlated with the malignant phenotype of HCC. Cox regression analysis revealed that these five lncRNAs can independently predict the prognosis of HCC patients, achieving an AUC value of 0.773, which is higher than that reported in other comparable studies.

Although several necrosis-related lncRNA models have been proposed, their ability to enhance the efficacy of immunotherapy in HCC patients remains unproven. Therefore, future in vivo and in vitro experiments are essential for further confirmation.

Apoptosis

Apoptosis is a tightly regulated form of programmed cell death. Properly functioning apoptosis eliminates cells damaged by infection and prevents the development of cancer. The extrinsic pathway of apoptosis is initiated by external stimuli through death receptors, including Fas receptor, DR4/DR5, TNF-R, and TNF-related apoptosis-inducing ligand receptors, which are present on various cell surfaces. The intrinsic pathway can be regulated or activated by internal stimuli such as DNA damage and oxidative stress. Proteins like Bax and Bcl-2, located on the mitochondrial membrane, serve as key mediators of the intrinsic apoptosis pathway. Additionally, there exists a perforin/granzyme-mediated pathway.

Apoptosis plays a crucial role in the tumorigenesis, proliferation, and metastasis of tumors. Tumor cells evade apoptosis, contributing to tumorigenesis[59,60]. The inhibition of apoptosis can result in uncontrolled cell proliferation and tumor expansion[61,62]. A well-studied lncRNA in cancer research is paraventular assembly transcript 1 (NEAT1), which is transcribed from the multiple endocrine neoplasia gene on chromosome 11q13.1[63,64]. Numerous studies have demonstrated the association between NEAT1 and various malignancies including HCC[65-68]. Knockdown of NEAT1 has been shown to enhance apoptosis and reduce proliferation of HCC cells. Furthermore, NEAT1 overexpression has been found to suppress pro-inflammatory cytokine production and protect cells by modulating apoptosis control mechanisms[69]. Overall, NEAT1 knockdown exhibits inhibitory effects on HCC cell proliferation, migration, and invasion[70].

Additionally, lncRNA CASC9 hinders miR-424-5p activity to promote HCC cell proliferation, invasion, and migration while suppressing apoptosis[71]. LncRNA AIRN regulates STAT1 ubiquitination to influence liver cancer cell growth and programmed cell death[72], whereas lncRNA ST8SIA6-AS1 targets miR-4656/HDAC11 axis to facilitate liver cancer cell proliferation as well as induce apoptosis[73].

Existing evidence supports multiple regulatory pathways involving lncRNAs as promising prognostic predictors and therapeutic targets for HCC. However, it should be noted that many studies have primarily focused on analyzing the impact of lncRNAs on HCC using in vitro models. Therefore, future comprehensive analyses incorporating in vivo animal experiments are warranted for a more thorough understanding of lncRNA regulation.

Ferroptosis

Ferroptosis, a distinctive form of programmed cell death discovered by Brent R. Stockwell's laboratory in 2012, is characterized by the lethal accumulation of iron-dependent lipid peroxides localized on the membrane[74-76]. The main features are changes in mitochondrial morphology, including the mitochondrial membrane becoming dense with accompanying smaller size, and outer membrane rupture and reduction or disappearance of mitochondrial cristae[77,78]. Inducing iron-mediated cell death in the context of malignancy has emerged as a highly promising approach that may synergize with cancer immunotherapy and effectively target resistant and metastatic cancers[79,80]. Glutathione peroxidase 4 (GPX4) is known to be a crucial regulator of iron-induced cell death, while sorafenib is recognized as one of the targeted drug options for advanced HCC[81]. Li et al[82] found that tumor cells can develop primary or secondary resistance to sorafenib, and HCG18 inhibits GPX4 through binding with miR-450b-5p, promoting iron-mediated apoptosis inhibited by GPX4 and overcoming sorafenib resistance in HCC. Xu et al[83] used Pearson assay to assess the correlation between differentially expressed lncRNAs in 374 HCC samples and 50 normal liver samples from the TCGA. They identified a signature based on nine lncRNAs (CTD-2033A16.3, CTD-2116N20.1, CTD-2510F5.4, DDX11-AS1, LINC00942, LINC01224, LINC01231, LINC01508 and ZFPM2-AS) which served as an independent prognostic model for liver cancer associated with iron-induced cell death irrespective of multiple clinicopathological parameters. Furthermore, in vitro and in vivo experiments have confirmed that the lncRNA HEPFAL can attenuate migration and invasion capabilities of liver cancer cells while accelerating apoptosis specifically in ferroptotic liver cancer cells through regulation of SLC7A11 ubiquitination[84].

Pyroptosis

Pyroptosis is an inflammatory form of programmed cell death characterized by cellular swelling and dissolution, accompanied by the release of a diverse array of pro-inflammatory factors. The underlying mechanism involves caspase-mediated cleavage of the substrate, leading to the formation of pores in the plasma membrane. This is followed by the subsequent release of inflammatory factors, ultimately resulting in membrane rupture and cell death[85]. As a regulated mode of cell death, pyrodeath exhibits accelerated kinetics and elicits a more robust inflammatory response compared to other forms of cell demise. Furthermore, inflammation triggered by pyrodeath can potentiate the functional attributes of tumor-infiltrating immune cells while inducing potent anti-tumor immunity[86,87]. Continuous exposure to inflammatory factors released upon pyrogenic activation poses an increased risk for cancer development in normal tissues and cells[88,89]. Recently conducted studies have demonstrated a close association between pyrodeath and tumor development as well as immune response[90-92]. Wu et al[93] developed an individualized prognostic risk model for HCC based on the relative expression sequence of pyrolysis-associated PRlncRNAs within the in-sample dataset. They established 11 LncRNA-miRNA-mRNA regulatory axes linked to pyrodeath and identified that high-risk patients may exhibit excessive pyrodeath, resulting in reduced sensitivity to immunotherapy. One experiment demonstrated that among the pyroptosis-associated lncRNAs, ZFPM2-AS1, KDM4A-AS1, and LUCAT1 were identified as potential risk factors, whereas CRYZL2P-SEC16B and AC008549.1 were identified as potential protective factors[94].

Autophagy

Autophagy serves as the principal mechanism responsible for the degradation and recycling of diverse cellular components to lysosomes[95]. However, in cancer, autophagy appears to exhibit a contrasting role by impeding early tumor development while facilitating metabolic adaptation and maintenance of established and metastatic tumors. Certain aspects of the autophagy process may contribute to malignant diseases. Tumors possess the ability to overcome autophagy-induced growth inhibition in order to promote tumor progression, while also preserving or reinstating autophagy for survival and sustenance of established tumors[96-99]. Maternal expression gene 3 (MEG3) is a novel tumor suppressor gene located on chromosome 14q32, and interleukin-enhancing binding factor 3 (ILF3) is a MEG3-binding protein. Compared to normal hepatocytes, HCC cells exhibit significantly decreased MEG3 expression. Adenosine inhibits autophagy in HepG2 cells and upregulates MEG3 expression. Overexpression of MEG3 leads to reduced ILF3 expression in HepG2 cells, while downregulation of ILF3 suppresses autophagy through decreased Beclin-1 expression. Overall, MEG3 overexpression deactivates the Beclin-1 signaling pathway through downregulation of ILF3, activates the PI3K/Akt/mTOR pathway, inhibits autophagy, and enhances cytotoxic effects on HCC cells[100-103]. Gu et al[104] discovered that HOTAIRM1, a specific lncRNA located within an evolutionarily highly conserved HOX gene cluster, exhibits differential expression between lenvatinib-resistant HCC cells and their parental counterparts. Downregulation of HOTAIRM1 decreases autophagy levels in lenvastini-resistant HCC cells and increases cell sensitivity to lenvastinib both in vitro and in vivo when combined with autophagy inhibitors. The resistance of HCC to lenvatinib is influenced by the regulatory axis involving HOTAIRM1-miR-34a-Beclin-1.

Microtubule-associated protein 1 light chain 3-II (LC3-II) serves as a marker for autophagosome formation[105]. HULC promotes HCC cell metastasis and proliferation via the Beclin 1 and LC3 pathways[106]. In HCC cells transfected with HULC, LC3-II and Beclin 1 expression levels were elevated, while the level of p62 was markedly reduced. Additionally, an increased number of autophagic vesicles were observed, indicating that HULC overexpression enhances autophagosome formation in HCC cells.

Cuproptosis

Cuproptosis represents a novel form of programmed cell death that was first introduced in 2022, quickly garnering significant attention from researchers globally. The primary biological processes associated with cuproptosis are oxidative phosphorylation and the tricarboxylic acid (TCA) cycle. In vitro experiments identified five lncRNAs, FOXD2-AS1, NRAV,MED8-AS1, WARS2-AS1, and MKLN1-AS, that play roles in regulating glycolysis, oxidative phosphorylation, and the TCA cycle, suggesting their potential involvement in cuproptosis[107]. Further studies revealed that only WARS2-AS1 and MKLN1-AS significantly influenced apoptosis in HCC cells. Additionally, another study demonstrated that CDKN2A, a gene implicated in cuproptosis, exhibited the most pronounced expression in HCC and showed a strong positive correlation with lncRNA DDX11-AS1[108]. Despite these findings, the precise mechanisms underlying cuproptosis in HCC remain elusive, necessitating further research to elucidate these processes.

DISCUSSION

Liver cancer poses a significant threat to human health. Early diagnosis of liver cancer can markedly improve patient prognosis. In recent years, the introduction of novel diagnostic markers such as des-gamma-carboxy prothrombin (DCP) has enhanced the accuracy of liver cancer diagnosis; however, these markers still possess certain limitations. With the deepening research into lncRNAs, particularly the elucidation of their relationship with liver cancer, an increasing number of lncRNAs have been identified as potential biomarkers for early liver cancer detection. The combination of lncRNAs with established markers like alpha-fetoprotein and DCP may significantly enhance the efficacy of early liver cancer diagnosis.

The current challenge lies in the fact that while statistical analysis has identified numerous lncRNAs associated with liver cancer development, such as HULC, UCA1, CCAT1, MEG3, and NEAT1, their specific regulatory mechanisms remain complex and multifaceted. For instance, lncRNA NEAT1 is highly expressed in liver cancer tissues and exerts its effects through multiple pathways. It can influence necrosis by regulating key molecules like RIPK1 and RIPK3, and it can indirectly modulate the necroptosis pathway by acting as a molecular sponge for miRNAs. However, existing research on lncRNAs in liver cancer predominantly focuses on individual signaling pathways, with limited studies systematically investigating the role of a single lncRNA across multiple pathways to elucidate how they collectively regulate tumor progression, invasion, and metastasis. Future research should aim to accurately translate these findings into clinical applications, potentially targeting lncRNAs to inhibit liver cancer progression.

In addition, it is well established that certain lncRNAs not only exert regulatory functions in HCC patients but also play significant roles in the progression of other malignancies such as pancreatic, gastric, and breast cancers. Monitoring specific lncRNAs enables the prospective prediction of HCC development trends, including potential metastatic patterns. This would allow clinicians to enhance patient management strategies and improve prognostic outcomes for HCC patients.

CONCLUSION

The research on apoptosis has been ongoing for over 30 years; however, the effectiveness of therapeutic agents targeting apoptosis regulators, such as apoptosis-associated cystease or B-cell lymphoma-2 family proteins, in antitumor therapy is limited[109]. Targeting non-apoptotic cell death presents a promising strategy to enhance the efficacy of immunotherapy in HCC treatment. Nevertheless, it remains uncertain whether long-term induction of nonapoptotic RCD by anticidal drugs benefits HCC patients, as DAMPs released through nonapoptotic RCD may also trigger death in other normal cells[110]. Therefore, there is an urgent need to develop more specific cell death inducers that selectively act on HCC tumor cells with minimal impact on normal tissues.