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. 2024 Oct 17;15:569. doi: 10.1007/s12672-024-01408-z

Circ_0001047 inhibits prostate cancer progression and enhances abiraterone sensitivity via miR-122-5p/FKBP5/PHLPP1/AKT axis in vitro

Zhenjie Chen 1,2,#, Shi Fu 1,#, Yiqian Shan 3,#, Zexi He 1, Jun Gu 1, Haichao Wu 1, Jiawei Lin 1, Yinglong Huang 1, Haifeng Wang 1, Yangbai Lu 2,✉, Mingxia Ding 1
PMCID: PMC11486870  PMID: 39419900

Abstract

Prostate cancer (PCa), with high heterogeneity and poor prognosis, is one of the most common malignant tumors in men. Circular RNAs (circRNAs) have been identified in tumor progression and resistance to medication in numerous studies. However, the role of circ_0001047 in PCa is unclear. In this research, we found that circ_0001047 had low expression in PCa cells and tissues and was negatively correlated with testosterone secretion in vivo. Overexpression of circ_0001047 inhibited the proliferation, migration, invasion, and anti-apoptotic abilities of human PCa cells in vitro. Mechanistically, circ_0001047 promoted the expression of FKBP5 through sponge adsorption of miR-122-5p and then inhibited the proliferation, anti-apoptotic migration, and invasion abilities of PCa cells. In addition, overexpression of circ_0001047 enhanced the sensitivity of PCa cells to abiraterone by inhibiting AKT phosphorylation activation through upregulation of FKBP5/PHLPP1. This study revealed a novel mechanism by which circ_0001047 regulates PCa progression and treatment sensitivity via the miR-122-5p/FKBP5/PHLPP1/AKT axis. These findings deepen our comprehension of the molecular mechanisms in latent PCa progression and treatment resistance.

Graphical Abstract

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Keywords: Prostate cancer, circ_0001047, miR-122-5p, FKBP5, AKT, Abiraterone

Introduction

Prostate cancer (PCa) is one of the most common malignant tumors in men, accounting for the second-leading incidence and fifth-leading mortality of male malignant tumors worldwide. In developed countries, its incidence ranks first among malignant tumors in males, and its mortality ranks second [1, 2]. Due to the lack of characteristic symptoms of early PCa, it often develops into intermediate-advanced cancer when diagnosed. Androgen deprivation therapy (ADT) is the current mainstay of treatment for intermediate to advanced PCa, but almost all patients develop castration-resistant prostate cancer (CRPC) within 2 years of ADT therapy [3]. In recent years, new endocrine therapy drugs, including abiraterone, have been approved as new treatments for CRPC. However, most patients are prone to primary or acquired resistance to these new endocrine therapies [3, 4]. Therefore, further in-depth study of the molecular mechanisms of PCa development and drug resistance is of great significance for improving the therapeutic effects for PCa and formulating individualized treatment strategies.

Circular RNAs (circRNAs) are formed by reverse splicing of exons or introns. Their structures are stable and not easily degraded by the exonuclease RNaseR [5]. They have unique advantages as novel tumor markers. In addition, circRNAs have multiple biological functions and can participate in the regulatory network of competitive endogenous RNAs (ceRNAs) by absorbing microRNAs (miRNAs) or binding to RNA-related proteins to form complexes [6]. Some circRNAs can exert biological effects by expressing proteins or polypeptides [7, 8]. Studies have increasingly confirmed that circRNAs play a crucial part in the occurrence, development, and treatment resistance of many common malignancies [9]. So far, 76,311 circRNAs have been identified in PCa samples [10], but the roles of these circRNAs in PCa are primarily unknown.

Circ_0001047 is transcriptionally spliced from the NCAPH gene. NCAPH encodes the regulatory subunit H of the non-SMC lectin I complex, which together with two other subunits, NCAPG and NCAPD2, forms the non-SMC lectin I complex [11, 12]. Studies have shown that NCAPH is upregulated in many common cancers, such as hepatocellular carcinoma, bladder cancer, colon cancer, pancreatic cancer, and PCa and plays a role in promoting cancer [13–16]. Silencing the expression of NCAPH in PCa can effectively restrain the migration and invasion ability of PCa cells, and high NCAPH expression is closely relatedto a higher clinical grade, staging, and lower survival rate in PCa patients [15, 16].

Given the theory that the production of circRNA and the pre-mRNA splicing of the source gene are mutually competitive [17], we speculate that circ_0001047, which is transcriptionally spliced from the NCAPH gene, may have low expression in PCa and play a tumor suppressor role. This research aimed to investigate the role and molecular mechanism of circ_0001047 in PCa. The findings of this study may help elucidate a novel mechanism of PCa progression and drug resistance.

Materials and methods

Tissue sample collection

Twenty-three pairs of PCa tissue and adjoining non-tumor tissue specimens were obtained from the Second Affiliated Hospital of Kunming Medical University, and no patient experienced chemoradiotherapy before surgery. The ethics committee approved the study of the Second Affiliated Hospital of Kunming Medical University, and all participants signed informed consent.

Cell culture

Human PCa cell lines 22RV1, LNCaP, DU145, PC-3 and human normal prostate stromal immortalized (WPMY-1) cells were derived from the Urinary Tumor Cell Bank of the Central Laboratory of the Second Affiliated Hospital of Kunming Medical University. 293 T cells were offered by Kunming Institute of Zoology, Chinese Academy of Sciences. All cells were cultured in Dulbecco’s modified eagle medium (DMEM) with high glucose or Roswell Park Memorial Institute (RPMI) 1640 medium (HyClone; Logan, UT, USA) containing 10% fetal bovine serum (FBS; Gibco; Waltham, MA, USA), 100 μg/ml streptomycin, and 100 IU/ml penicillin (Millipore; Burlington, MA, USA) in a 37 °C incubator with 5% CO2.

Quantitative real-time polymerase chain reaction (qRT-PCR)

Total RNA was refined from the PCa tissues and cells by TRIzol reagent (MRC, Germany) [18]. cDNA was obtained by reverse transcription using the SureScriptFirst-strand-cDNA-synthesis kit from GeneCopoeia (All-in-One™-miRNA-qRT-PCR-Detection-System-2.0-User-Manual kit for miRNA). qRT-PCR was carried out using the BlazeTaq™ SYBR® Green qPCR Mix 2.0 kit from GeneCopoeia. The primer sequences were as follows: circ_0001047: 5'-AACTTGGTAGCTGAGCCTCA-3'(F),5'-GTTTTCTGATTGGGAAGGAGCA-3'(R);GAPDH:5'-CGCTGAGTACGTCGTGGAGTC'(F),5'-GCTGATGATCTTGAGGCTGTTGTC-3'(R);miR-122-5p:5'-TGGAGTGTGACAATGGTGTTTG(F),5'-GCTGTCAACGATACGCTACGTAACG-3'(R); U6:5'-CTCGCTTCGGCAGCACA-3'(F), and 5'-AACGCTTCACGAATTTGCGT-3'(R).

RNase R assay

RNA was refined from cells and then divided into RNaseR (Epicenter) incubation or no incubation groups. The expression of hsa_circ_0001047 and linear NCAPH was detected by qRT-PCR.

Cell transfection

The hsa_circ_0001047 overexpression, interference, and control vectors were constructed by GeneCopoeia, including sh-hsa_circ_0001047, m-hsa_circ_0001047, miR-122-5p mimics, and their blank controls. They were introduced into 293 T cells using Liposome 2000 (Invitrogen) to package the lentivirus, and the lentivirus infected LNCaP cells and PC3 cells [19].

Cell counting kit-8 assay(CCK-8)

After each stable cell line was digested with 0.25% trypsin, 1 × 104 cells/100 μL were transferred into a 96-well plate. After the cells conglutinated overnight, the cell proliferation was measured at five time points of 0 h, 24 h, 48 h, 72 h, and 96 h. Five duplicate wells were set for each treatment group, 10 μL of CCK-8 reagent was merged to each duplicate well, and a microplate reader measured the OD value after culturing for 2 h [18, 20].

Cell apoptosis assay

Apoptosis detection kit Annexin V-PE/7-AAD (BD) was used for cell staining. Stably selected cell lines were colored with Annexin V-PE and 7-AAD and then detected by flow cytometry (Thermo Fisher Scientific; Waltham, MA, USA) to analyze cell apoptosis [18, 21].

Wound healing assay

The stable selected cell group was inoculate into a six-well plate. After 24 h, wounds were created within the cells with a 200 ml pipette tip. Ranging was measured and photographed (Image-Pro) at the 0 h and 24 h time points to evaluate the cell migration rate [18].

Transwell assay

After the stable selection, the cell group was inoculated into a 24-well plate (Matrigel was pre-coated in the chamber in advance), and the over chamber contained a serum-free medium. A medium containing 10% fetal bovine serum was added to the underside chamber. After 24 h, cells were tinted with 0.5% crystal violet, and pictures were taken and counted under a microscope [19, 20].

Bioinformatics analyses

The target miRNA of circ_0001047 was predicted using circRNA Interactome (https://circinteractome.nia.nih.gov/) and CircBank (http://www.circbank.cnTarget gene prediction software TargetScan (http://www.targetscan.org/), DIANA (DIANA tools—Tarbase v8), miRanda, PicTar, and PITA were used to predict miR-29b-1-5p, miR-378c, miR-378 h, miR-122-5p, and miR-6801-5p downstream target genes and screen out their common target gene, FKBP5 [20].

Dual-luciferase reporter gene assay

On the basis of the binding site of miR-122-5p in circ_0001047 and FKBP5 3'-UTR, WT and MUT vectors of circ_0001047 and FKBP5 3'-UTR were constructed with pmirGLO reporter vector. LNCaP cells were co-transfected with the vector with miR-122-5p mimics or miR-NC. Luciferase activity was detected with a dual-luciferase reporter system (GeneCopoeia) [21, 22].

Western blot

Total protein was refined with RIPA lysis buffer (Beyotime, Shanghai, China), isolated by SDS-PAGE gel, and transferred to the PVDF membrane (Invitrogen). It was incubated overnight with FKBP5, p-AKT (p-Thr308), p-AKT (p-Ser473), and AKT. After incubation with goat anti-rabbit antibody, protein bands were visualized with the Beyotime kit (Beyotime). ImageJ software was used to scan the grayscale and compare it with the β-actin internal reference to calculate the relative expression of the target protein. All antibodies were from abcam(FKBP5 abcam ab126715, p-AKT (p-Thr308) abcam ab38449, p-AKT (p-Ser473) abcam ab81283, AKT abcam ab238477) [22, 23].

Statistical methods

Results are represent as mean ± standard deviation. The experimental data were analyzed by t-test or one-way analysis of variance. Statistical tests were carried out using GraphPad Prism 6.0 software. At P < 0.05, the difference demonstrated statistical significance.

Results

This research aimed to investigate the role and molecular mechanism of circ_0001047 in PCa. We first tested the expression of circ_0001047 in PCa cells and tissues. Then we performed cell function experiments to verify the effects of circ_0001047 on cell proliferation, apoptosis, migration, and invasion abilities. Bioinformatics analysis and recovery experiments revealed the mutual effect between circ_0001047 and the miR-122-5p/FKBP5/AKT, signaling axis. Finally, a drug sensitivity test preliminarily explored the effect of circ_0001047 on abiraterone sensitivity in PCa. Collectively, the findings of this study may help elucidate a novel mechanism of PCa progression and drug resistance.

Circ_0001047 is downregulated in PCa

Circ_0001047 was transcriptionally spliced from the NCAPH gene located on chromosome 2q11.2 (Fig. 1A). We used Premier software to design and synthesize primers according to the principle of circRNA primer design and verified the primers (Fig. 1B). The results showed that the product sequence was consistent with the sequence of circ_0001047. The stabilities of circ_0001047 and NCAPH mRNA were detected under the action of RNase, and the results showed that circ_0001047 was stable under the action of RNase, whereas NCAPH mRNA was significantly degraded (Fig. 1C). The expression levels of circ_0001047 in human PCa cell lines and 23 pairs of PCa tissues were tested by qRT-PCR. Compared with adjacent normal tissues and WPMY-1 cells, circ_0001047 was expressed at a significantly lower rate in PCa tissues and cell lines (Fig. 1D/E). On this basis, the clinical correlation analysis indicated that the expression of circ_0001047 in vivo was negatively related to testosterone secretion (p < 0.05) and negatively related to prostate-specific antigen (PSA) expression (p > 0.05), but the difference was not statistically significant (Fig. 1F/H).

Fig. 1.

Fig. 1

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Circ_0001047 is downregulated in PCa tissues and cell lines. A. Schematic diagram of the formation of circ_0001047; B. Circ_0001047 primer sequencing map; C. Circ_0001047 and source gene NCAPH mRNA stability detection; D. The expression of circ_0001047 in PCa cell line and normal prostate cells tested by qRT-PCR; E. The expression of circ_0001047 in PCa and paracancerous tissue tested by qRT-PCR; F. Correlation analysis between the expression of circ_0001047 and testosterone; G. Correlation analysis between circ_0001047 expression and PSA

circ_0001047 plays a tumor suppressor role in PCa

To study the biological function of circ_0001047 in PCa cells, we constructed circ_0001047 stably overexpressed, interfered, and empty LNCap and PC3 cell lines and verified the interference or overexpression efficiency of circ_0001047 in LNCap and PC3 cells by RT-PCR (Fig. 2A/F).

Fig. 2.

Fig. 2

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Effects of interference/overexpression of circ_0001047 on the biological behavior of PCa cells. A/F. The interference/overexpression efficiency of circ_0001047 verified by qRT-PCR; B/G. Using CCK-8 to detect cell proliferation ability; C/H. Cell apoptosis detected by flow cytometry; D/I. Use of the scratch test to detect cell migration ability; E/J. Trans-well detected cell invasion ability

Then the effects of interference and higher expression of circ_0001047 on the proliferation, apoptosis, migration, and invasion of LNCap and PC3 cells were detected by CCK-8, flow cytometry, scratch assay, and Transwell assay. The results showed that higher expression of circ_0001047 could markedly inhibit the proliferation, anti-apoptotic migration, and invasion abilities of LNCap and PC3 cells, whereas interfering with the expression of circ_0001047 could enhance the proliferation, anti-apoptotic migration, and invasion abilities of LNCap and PC3 cells (Fig. 2).

circ_0001047 exerts tumor suppressor effect in PCa through sponge adsorption of miR-122-5p

A great deal of research has make clear that circRNAs can regulate the expression of downstream target genes by adsorbing miRNAs and then play a biological role [9]. Therefore, we investigated whether circ_0001047 could act as an miRNA sponge. First, CircBank (http://www.circbank.cn) was used to predict the target miRNAs of circ_0001047, and five miRNAs with binding sites to circ_0001047 were screened, including miR-29b-1-5p, miR-378c, miR-378 h, miR-122-5p, and miR-6801-5p (Fig. 3A).

Fig. 3.

Fig. 3

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Reply experiment. A. Circ_0001047 and 5 miRNA binding sites map; B. KEEG analysis diagram of circ_0001047; C. GO enrichment analysis map of circ_0001047; D/E. The dual-luciferase reporter gene detected the specific binding-site of circ_0001047 and miR-122-5p. F. Changes in the expression of miR-122-5p after interference/overexpression of circ_0001047; G. Using CCK-8 to detect cell proliferation ability; H. Detection of cell apoptosis by flow cytometry; I. Detect cell invasion ability by Transwell assay; J. Detection of cell migration ability by scratch assay

Then, KEGG and GO enrichment analysis was performed on the above five miRNAs using the mirPath database. KEEG analysis indicated (Fig. 3B) that the target gene functions of the miRNAs mentioned were enriched in ECM receptor interaction signaling pathways, proteoglycan and other types of o-sugar biosynthesis, and transcriptional dysregulation central carbon metabolism pathways in cancer. Moreover, the target genes of miR-122-5p were also enriched in the biological regulatory networks of prostate cancer, glioma, and small cell lung cancer. GO enrichment analysis showed (Fig. 3C) that circ_0001047 and its five related miRNA target genes function mainly in the transition of G1/S and G2/M of the mitotic cell cycle, mitotic nuclear membrane disassembly, intrinsic apoptosis signaling pathway, and cellular protein modification processes, cellular nitrogen compound metabolism, neurotrophin TRK receptor signaling, binding of protein-bound transcription factors, transcription of DNA templates, RNA catabolism, production of precursor metabolites and energy, phosphatidylinositol-mediated signal (PI3K-AKT-mTOR), fibroblast growth factor receptor signaling pathway, and cellular lipid metabolism are enriched. Notably, miR-122-5p is involved in all of the above biological processes. Therefore, we selected miR-122-5p as a further study object.

To explain the interaction between circ_0001047 and miR-122-5p, we used RT-qPCR to test the effect of interference and overexpression of circ_0001047 on miR-122-5p. The results suggest that higher expression of circ_0001047 could observably inhibit the expression of miR-122-5p, and knockdown of circ_0001047 could upregulate the expression of miR-122-5p (Fig. 3D). A dual-luciferase reporter assay was carried out to determine the targeted binding correlation between miR-122-5p and circ_0001047. Tests revealed that the miR-122-5p mimic could markedly inhibit the activity of wild-type circ_0001047 luciferase but had no remarkable effect on the activity of mutant circ_0001047 luciferase (Fig. 3E, F). The results suggest that circ_0001047 acts as a sponge for miR-122-5p in PCa.

To determine whether circ_0001047 suppresses the proliferation, apoptosis, migration, and invasion of PCa cells by interacting with miR-122-5p, we co-transfected LNCap cells with circ_0001047 overexpression vectors and miR-122-5p mimics for an in vitro recovery experiment. The results of CCK-8, flow cytometry, scratch assay, and Transwell assay indicated (Fig. 3G, H, I, J) that higher expression of miR-122-5p strengthened the proliferation, anti-apoptotic migration, and invasion abilities of PCa cells compared with the matched group, whereas up-regulated expression of circ_0001047 inhibited the promoting effect of miR-122-5p on PCa cells. These findings suggest that circ_0001047 inhibits PCa cell progression at least in part by uptake of miR-122-5p.

Circ_0001047 inhibits androgen secretion and enhances abiraterone sensitivity through regulation of FKBP5/AKT expression by miR-122-5p

To further explore the downstream molecules that the circ_0001047/miR-122-5p axis may regulate, the downriver common target genes of five miRNAs, including miR-122-5p, were forecasted using the TargetScan (http://www.targetscan.org/) database. It was found that their common target gene was FKBP5 (Fig. 4A). After reviewing the literature, it was found that FKBP5 is a target gene of androgen receptors (AR), which are closely related to PCa progression and drug resistance [24, 25]. To further validate the mutual effect between miR-122-5p and FKBP5, a dual-luciferase reporter assay was carried out with wild-type and mutant FKBP5 30-UTR sequences. The test results showed that the miR-122-5p mimic could markedly reduce FKBP5 wild-type luciferase activity but had no obvious effect on FKBP5 mutant luciferase activity (Fig. 4A/B).

Fig. 4.

Fig. 4

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circ_0001047 regulates the expression of FKBP5/AKT by adsorbing miR-122-5p. A/B. Detection of specific binding between FKBP5 and miR-122-5p using a dual-luciferase reporter gene; C/E. Expression changes of FKBP5 protein levels after interference/overexpression of circ_0001047 tested by Western blotting; D/F. The expression changes of FKBP5 in cells co-transfected with m-circ_0001047 and miR-122-5p mimics tested by Western blotting; G/H/I. Western blotting used to detect AKT protein phosphorylation level expression changes after interference/ overexpression of circ_0001047; J. T and DHT expression changes detected by ELISA after overexpression circ_0001047; K. Effects of LNCaP cells on abiraterone sensitivity after interference/overexpression of circ_0001047

The effects of overexpression or interference of circ_0001047 and co-transfection of miR-122-5p on FKBP5 expression were tested by Western blotting. The experiment results indicated that up-regulated expression of circ_0001047 markedly upregulated the expression of FKBP5, whereas knockdown of circ_0001047 downregulated the expression of FKBP5 (Fig. 4C/E). Conversely, co-transfection of miR-122-5p based on higher expression of circ_0001047 suppressed the promoting effect of circ_0001047 on FKBP5 protein expression (Fig. 4D/F). The aforesaid results indicated that miR-122-5p was negatively relevant with circ_0001047 expression, whereas FKBP5 expression was positively related to circ_0001047 expression.

Numerous studies have shown that during the treatment of PCa with drugs such as abiraterone, inhibition of androgen/AR/FKBP5 signaling can induce endocrine therapy resistance by mediating the activation of the PI3K-AKT-mTOR pathway [24, 25]. Therefore, we speculated that circ_0001047 might affect the sensitivity of PCa to abiraterone by regulating FKBP5 expression via miR-122-5p. We tested the effect of LNCaP cells on abiraterone sensitivity after interference or overexpression of circ_0001047 by CCK-8, and tests revealed that overexpression of circ_0001047 in LNCaP cells enhanced abiraterone sensitivity (Fig. 4K). In addition, the expression of T and DHT after enhanced expression of circ_0001047 was tested by ELISA, and the results indicate that enhanced expression of circ_0001047 could inhibit the synthesis of T and DHT in LNCaP cells (Fig. 4J). In addition, we tested the changes of AKT subunit phosphorylation sites in LNCap cells after interference and overexpression of circ_0001047 by Western blotting. The experiment results indicated that AKT phosphorylation was markedly inhibited after overexpression of circ_0001047, whereas AKT phosphorylation was enhanced after knockdown of circ_0001047 (Fig. 4G, H, I). These results suggest that overexpression of circ_0001047 inhibits testosterone secretion and enhances the sensitivity of PCa cells to abiraterone via the FKBP5/AKT signaling pathway.

Discussion

As a highly heterogeneous malignant tumor, the molecular mechanisms of PCa development and resistance to medication are highly complex. CircRNAs have been confirmed to play a pivotal role in the progression and treatment resistance of common malignancies [9]. Although the related research of circRNA in PCa was carried out relatively late, some progress has been made. For example, it was found that the spliced circRNA_ARC1 encoded by the androgen receptor (AR) can mediate PPARγ/MMP-9 signaling by adsorbing miR-125b-2-3p and miR-4736, thereby affecting PCa invasion [26]. Shi et al. [27] found that circMBOAT2 overexpressed in PCa facilitated the proliferation, migration, and invasion of PCa cells and was closely related to a higher Gleason score, pathological stage, and poor prognosis in patients. In this study, we confirmed for the first time that circ_0001047, which is transcriptionally spliced from the NCAPH gene, is significantly downregulated in PCa, and overexpression of circ_0001047 can inhibit the proliferation, migration, invasion, and anti-apoptotic abilities of PCa cells. The expression of circ_0001047 in vivo was negatively correlated with the amount of testosterone in PCa patients. Overexpression of circ_0001047 in vitro could markedly inhibit the synthesis of testosterone and dihydrotestosterone, suggesting that circ_0001047 may exert a tumor suppressor effect in PCa by reducing the amount of testosterone in vivo.

One of the main functions of circRNA is to participate in the ceRNA regulatory network and regulate gene expression [9]. In the present study, we confirmed that circ_0001047 exerts a tumor suppressor effect in PCa by targeting miR-122-5p through bioinformatics analysis and dual-luciferase reporting. Previous studies have confirmed that miR-122-5p is overexpressed in cancers and plays a role in promoting cancer. For example, miR-122-5p shows higher expression in renal cell carcinoma and promotes renal cell carcinoma’s proliferation, migration, and glycolysis by inhibiting PKM2 expression [28]. It was also reported that miR-122-5p could promote the invasion and epithelial-mesenchymal transition of triple-negative breast cancer by mediating the MAPK signaling pathway and inhibiting CHMP3 [29]. In this study, we found that higher expression of circ_0001047 could markedly inhibit the expression of miR-122-5p. The reverse experiment confirmed that higher expression of miR-122-5p can promote the proliferation, migration, invasion, and anti-apoptosis of PCa cells, and this promotion can be inhibited by circ_0001047, suggesting that miR-122-5p promotes cancer in PCa and could be regulated by circ_0001047.

Further mechanistic studies revealed that circ_0001047 could promote the expression of FKBP5 through sponge adsorption of miR-122-5p. FKBP5 is a target gene of the androgen receptor (AR), encoding the FK506 binding protein 5 belonging to the immunophilin family. It can regulate the distribution of steroid hormone receptors, including progesterone, androgen, and glucocorticoid receptors in the cytoplasm and nucleus, and play an essential role in the generation and development of PCa [30]. In this research, we confirmed a specific binding site between FKBP5 and miR-122-5p. Overexpression of circ_0001047 can relieve the inhibition of FKBP5 by sponge adsorption of miR-122-5p, thereby promoting the expression of FKBP5. In addition, many investigations in recent years have made clear that during ADT and novel endocrine therapy for PCa, inhibition of androgen, AR, and FKBP5 signaling can induce PCa endocrine therapy resistance by mediating the activation of the PI3K-AKT-mTOR pathway [24, 25, 31].

Mechanistically, inhibiting the AR signaling pathway reduces the expression of the AR target gene FKBP5, resulting in a decrease in the stability of PHLPP1, inhibiting the PHLPP1-mediated dephosphorylation of AKT Ser473 and thereby promoting the phosphorylation activation of the AKT signaling pathway [24, 25, 31–34]. Therefore, during androgen/AR targeted therapy, AR can induce endocrine therapy resistance, such as abiraterone, and promote the occurrence and development of CRPC through the compensatory activation of the PI3K-AKT-mTOR pathway mediated by the AR-FKBP5-PHlPP1-AKT signaling pathway. In this experiment, we confirmed that enhanced expression of circ_0001047 distinctly inhibited AKT phosphorylation, whereas knockdown of circ_0001047 enhanced AKT phosphorylation. In addition, we confirmed by drug sensitivity test that enhanced expression of circ_0001047 can enhance the sensitivity of PCa cells to abiraterone. It is suggested that circ_0001047 may enhance the sensitivity of PCa to abiraterone by inhibiting AKT signaling through regulating miR-122-5p/FKBP5.

Conclusion

In conclusion, this study confirmed that circ_0001047 was downregulated in PCa tissues and cells. Overexpression of circ_0001047 can activate FKBP5/PHLPP1 signaling through sponge adsorption of miR-122-5p and then inhibit AKT1 phosphorylation activation, which may participate in the occurrence and development of PCa and the regulation of resistance to medication. These findings deepen our comprehension of the molecular mechanisms latent in malignant PCa progression and resistance to medication.

Author contributions

Author contributions Mingxia Ding and Yangbai Lu were designed and wrote the study；Zhenjie Chen and Shi Fu were involved with the conception of the analyses; Jiawei Lin and Ying-long Huang were involved with performing the analyses;Zexi He; Jun Gu and Haichao Wu were involved Data collection/entry; And all authors were involved with interpretation of the data. Zhenjie Chen and Yi-Qian Shan wrote the paper. All authors provided their approval for the fnal version to be published. All authors agreed to be accountable for the accuracy and integrity of the work.

Funding

This work was supported by the following funds: National Natural Science Foundation of China (grant no. 82360603); College Science and Technology Innovation Team Construction Project of Yunnan Province (grant no. K1322107); Medical Leading Talents Project of Yunnan Province (grant no. L-2018009); Basic and Applied Basic Research Fund of Guangdong Province (grant no. 2022A1515220032); Guangdong Medical Science and Technology Research Foundation (grant no. B2023195); Zhongshan City People's Hospital Outstanding Youth Project (grant no. SG2023106).

Data availability

Data is provided within the manuscript or supplementary information files.

Declarations

Ethics approval and consent to participate

The study procedure conformed to the ethical guidelines of the Declaration of Helsinki, and the approval for the study was obtained from the Second Affiliated Hospital of Kunming Medical University. A written informed consent was obtained from patients enrolled.

Consent for publication

A written informed consent was obtained from patients to publish this paper.

Competing interests

The authors declare no competing interests.

Footnotes

Publisher's Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Zhenjie Chen, Shi Fu and Yiqian Shan have contributed equally to this work and should be regarded as co-first authors.

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