AKR1C1 could be a prognostic marker for HCC
To investigate the role of the LncRNA TCONS-00026762/AKR1C1 pathway in the treatment of HCC, we employed bioinformatics techniques to delineate the mechanistic involvement of AKR1C1 in HCC pathogenesis. Bioinformatic analysis revealed a significant upregulation of AKR1C1 in the HCC tumor cohort when compared to the normal group (t-test, P < 0.05; Fig. 1A). Intriguingly, HCC patients characterized by lower AKR1C1 expression levels exhibited longer overall survival as opposed to those with elevated expression levels (Log-rank test, P < 0.05; Fig. 1B). Further, differential expression analysis disclosed that AKR1C1 was overexpressed in early-stage tumors (stages 1–2) as compared to late-stage tumors (stages 3–4) (t-test, P < 0.05; Fig. 1C). Collectively, these findings underscore the potential of AKR1C1 as a prognostic marker for HCC.
Complementing these observations, existing literatures have implicated AKR1C1 in a myriad of cellular processes, including cancer autophagy, ferroptosis, and chemoresistance. In our study, we ascertained that heightened expression levels of AKR1C1 significantly influenced the activity scores across 16 distinct autophagy-related pathways and one ferroptosis-related pathway, as cataloged in Table 1. Additionally, Pearson’s correlation analysis yielded a notable negative association between AKR1C1 and PD1 (P = 0.00026; Fig. 1D). Considering these empirical insights and bioinformatic interpretations, we hypothesize that targeted therapeutic interventions against AKR1C1 in HCC may be intricately associated with modulating autophagy, ferroptosis, and chemotherapy sensitivity.
Table 1
Identification of the pathways significantly related to autophagy and ferroptosis between high and low AKR1C1 expression groups through gene set variation analysis
Pathway
|
Group1
|
Group 2
|
Pvalue
|
Method
|
GOBP_LYSOSOMAL_MICROAUTOPHAGY
|
AKR1C1_high
|
AKR1C1_low
|
0.031
|
T-test
|
GOBP_POSITIVE_REGULATION_OF_MACROAUTOPHAGY
|
AKR1C1_high
|
AKR1C1_low
|
0.03
|
T-test
|
GOBP_CHAPERONE_MEDIATED_AUTOPHAGY
|
AKR1C1_high
|
AKR1C1_low
|
0.038
|
T-test
|
GOBP_NEGATIVE_REGULATION_OF_AUTOPHAGY_OF_MITOCHONDRION
|
AKR1C1_high
|
AKR1C1_low
|
0.015
|
T-test
|
REACTOME_LATE_ENDOSOMAL_MICROAUTOPHAGY
|
AKR1C1_high
|
AKR1C1_low
|
0.018
|
T-test
|
WP_AUTOPHAGY
|
AKR1C1_high
|
AKR1C1_low
|
0.012
|
T-test
|
KUMAR_AUTOPHAGY_NETWORK
|
AKR1C1_high
|
AKR1C1_low
|
0.0028
|
T-test
|
GOBP_REGULATION_OF_AUTOPHAGY
|
AKR1C1_high
|
AKR1C1_low
|
0.0067
|
T-test
|
GOBP_NEGATIVE_REGULATION_OF_AUTOPHAGY
|
AKR1C1_high
|
AKR1C1_low
|
0.0014
|
T-test
|
GOBP_POSITIVE_REGULATION_OF_AUTOPHAGY
|
AKR1C1_high
|
AKR1C1_low
|
0.0054
|
T-test
|
GOBP_NEGATIVE_REGULATION_OF_MACROAUTOPHAGY
|
AKR1C1_high
|
AKR1C1_low
|
0.0052
|
T-test
|
GOBP_AUTOPHAGY_OF_PEROXISOME
|
AKR1C1_high
|
AKR1C1_low
|
0.0017
|
T-test
|
GOBP_REGULATION_OF_AUTOPHAGY_OF_MITOCHONDRION_IN_RESPONSE_TO_MITOCHONDRIAL_DEPOLARIZATION
|
AKR1C1_high
|
AKR1C1_low
|
0.0015
|
T-test
|
REACTOME_AUTOPHAGY
|
AKR1C1_high
|
AKR1C1_low
|
0.0016
|
T-test
|
REACTOME_SELECTIVE_AUTOPHAGY
|
AKR1C1_high
|
AKR1C1_low
|
0.0053
|
T-test
|
WP_CLOCKCONTROLLED_AUTOPHAGY_IN_BONE_METABOLISM
|
AKR1C1_high
|
AKR1C1_low
|
0.0028
|
T-test
|
Ferroptosis
|
AKR1C1_high
|
AKR1C1_low
|
0.02
|
T-test
|
TCONS-00026762 knockdown inhibits autophagy, promotes ferroptosis, and enhances sensitivity to sorafenib in HCC cells by reducing AKR1C1 expression
To corroborate the findings from our bioinformatics analysis, we assessed the impact of the LncRNA TCONS-00026762/AKR1C1 axis on autophagy, ferroptosis, and sensitivity to sorafenib in HCC cells. Initially, the expression of TCONS-00026762 and AKR1C1 were upregulated in HCC cell lines (Huh7 and SMMC-7721 cells) compared to normal live line (HL-7702 cells) (P < 0.01; Fig. 2A). Since the expression levels of TCONS-00026762 andAKR1C1 were slightly higher in Huh7 cells than in SMMC-7721 cells, Huh7 cells were selected for subsequent assays (Fig. 2A). Then, transfection with sh-TCONS-00026762-1 and sh-TCONS-00026762-2 led to a marked decrease in the relative mRNA expression of both TCONS-00026762 and AKR1C1 in Huh7 cells (P < 0.01; Fig. 2B). Given slightly lower TCONS-00026762 and AKR1C1 expression levels in sh-TCONS-00026762-1-transfecetd Huh7 cells than TCONS-00026762-2-transfecetd cells (Fig. 2B), the sh-TCONS-00026762-1 lentiviral plasmid was chosen for subsequent experiments. Notably, the viability of Huh7 cells was compromised following sh-TCONS-00026762 transfection, a decrement that was effectively reversed upon AKR1C1 overexpression (P < 0.01; Fig. 2C).
Furthermore, immunofluorescence staining revealed that sh-TCONS-00026762 substantially attenuated the fluorescence signal corresponding to LC3, an autophagy marker (P < 0.01; Fig. 2D). This attenuation was counteracted by the introduction of oe-AKR1C1 (P < 0.01; Fig. 2D). Concordantly, western blot analysis of LC3 protein levels corroborated the results obtained through immunofluorescence staining (P < 0.01; Fig. 2E). Collectively, these data suggest that TCONS-00026762 knockdown inhibits autophagy in HCC cells by downregulating AKR1C1 expression.
In terms of ferroptosis, sh-TCONS-00026762-mediated elevations in the contents of MDA, 4-HNE, and iron were significantly alleviated by AKR1C1 overexpression (P < 0.01; Fig. 3A). Similarly, knockdown of TCONS-00026762 led to a marked downregulation in the two key ferroptosis regulators, GPX4 and SLC7A11 (P < 0.01; Fig. 3B), and lowered levels of them are commonly deemed as ferroptosis indicators (19, 20). However, the levels of GPX4 and SLC7A11 were restored by AKR1C1 overexpression (P < 0.01; Fig. 3B). Taken together, these findings indicate that knockdown of TCONS-00026762 promotes ferroptosis in HCC cells by decreasing AKR1C1 expression.
Lastly, the Huh7-SR group exhibited elevated levels of TCONS-00026762 and AKR1C1 mRNA expression in comparison to the control group (P < 0.05; Fig. 3C). Concurrently, overexpression of AKR1C1 mitigated the decreased viability of Huh7-SR cells induced by TCONS-00026762 knockdown in the context of sorafenib treatment (P < 0.01; Fig. 3D). These cumulative data imply that knockdown of TCONS-00026762 enhances the sensitivity of sorafenib-resistant HCC cells to sorafenib treatment by reducing AKR1C1 expression.
ZnS inhibits autophagy, promotes ferroptosis, and enhances sensitivity to sorafenib in HCC cells by blocking the TCONS-00026762/AKR1C1 axis
To investigate the role of ZnS in modulating autophagy, ferroptosis, and sorafenib sensitivity in HCC cells via the lncRNA TCONS-00026762/AKR1C1 pathway, we treated Huh7 cells with ZnS, either in the presence or absence of oe-TCONS-00026762. Initially, we assessed the impact of ZnS on the expression levels of TCONS-00026762 and AKR1C1. qRT-PCR analysis revealed that ZnS treatment led to a notable reduction in the expression of both TCONS-00026762 and AKR1C1 when compared to untreated controls (P < 0.01; Fig. 4A). This downregulation was effectively counteracted by the overexpression of TCONS-00026762 (P < 0.01; Fig. 4A).
Following this, ZnS was observed to significantly diminish both cell viability (P < 0.01; Fig. 4B) and migratory capabilities of Huh7 cells (P < 0.01; Fig. 4D), while concurrently enhancing apoptosis (P < 0.01; Fig. 4C). Interestingly, these effects of ZnS were abolished upon oe-TCONS-00026762 transfection (P < 0.01; Fig. 4B-D). Importantly, overexpression of TCONS-00026762 effectively reversed the ZnS-mediated downregulation of LC3 (P < 0.01; Fig. 4E-F).
In relation to ferroptosis, TCONS-00026762 overexpression significantly attenuated the ZnS-induced increases in levels of MDA, 4-HNE, and iron, while simultaneously reversing the decreased GPX4 and SLC7A11 expression (P < 0.01; Fig. 4G-H). Additionally, the ZnS-induced reduction in the viability of sorafenib-resistant Huh7-SR cells was also significantly nullified by TCONS-00026762 overexpression (P < 0.01; Fig. 4I).