Downregulation of circRNA_100876 Inhibited Progression of NSCLC In Vitro via Targeting miR-636

The potential role of circular RNAs -regulated PI3K signaling in non-small cell lung cancer: Molecular insights and clinical perspective

Non-small cell lung cancer (NSCLC), accounting for more than 80% of all cases, is the predominant form of lung cancer and the leading cause of cancer-related deaths worldwide. Significant progress has been made in diagnostic techniques, surgical interventions, chemotherapy protocols, and targeted therapies at the molecular level, leading to enhanced treatment outcomes in patients with NSCLC. Extensive evidence supports the use of circular RNAs (circRNAs), a specific category of naturally occurring non-coding small RNAs (ncRNAs), for the diagnosis, monitoring of treatment efficacy, and assessment of survival in NSCLC. CircRNAs have been identified to play significant roles in various aspects of cancer formation, either as tumor suppressors or tumor promoters, contributing to cancer development through several signaling pathways, including the phosphoinositide 3-kinases (PI3Ks) pathway. This pathway is well-established because of its regulatory role in essential cellular processes. CircRNAs regulate the PI3K/AKT pathway by targeting diverse cellular elements. This review aims to provide insight into the involvement of several circRNAs linked to the PI3K/AKT pathway in NSCLC.

Circ_0000877 accelerates proliferation and immune escape of non-small cell lung cancer cells by regulating microRNA-637/E2F2 axis

BACKGROUND

Recently, circular RNA (circRNA) has become a vital targeted therapy gene for non-small-cell lung cancer (NSCLC) cells. CircRNA_0000877 (Circ_0000877) has been researched in diffuse large B-cell lymphoma (DLBCL). However, whether circ_0000877 regulated NSCLC cell progression is still poorly investigated. The research attempted to investigate the influence of circ_0000877 in NSCLC.

METHODS

Circ_0000877 levels in NSCLC tissues and cell lines were determined applying RT-qPCR. Cell functions were evaluated by CCK-8, EdU, flow cytometry, ELISA, and western blot. Gene interactions were predicted by Cirular RNA interactome database and Target Scan website and certified by dual-luciferase reporter, RIP, and RNA pull-down assays. Finally, mice experimental model was established to explore the effects of circ_0000877 on tumor growth in vivo.

RESULTS

The elevated trend of circ_0000877 expression was discovered in NSCLC tissues compared to para-carcinoma tissues. The clinicopathological data uncovered that up-regulated circ_0000877 was linked to tumor size, differentiation, and TNM stages of NSCLC patients. Knockdown of circ_0000877 inhibited the proliferation, triggered apoptosis, and prohibited immune escape in NSCLC cells. It was certified that miR-637 was directly interacted with circ_0000877 and targeted by E2F2. Overexpressed E2F2 strongly overturned the functions of circ_0000877 knockdown in NSCLC cells. Mice experimental data demonstrated that circ_0000877 knockdown suppressed tumor growth in vivo.

CONCLUSION

The research demonstrated that circ_0000877 exhibited the promotive effect on NSCLC cells proliferation and immune escape by regulating miR-637/E2F2 axis.

Identification of expression profiles and prognostic value of RFCs in colorectal cancer

Colorectal cancer (CRC) ranks among the most prevalent cancers globally, with its incidence closely tied to DNA damage. The Replication Factor C (RFC) complexes comprises five protein subunits: RFC1, RFC2, RFC3, RFC4, and RFC5. These RFC complexes play crucial roles in DNA replication, repair pathways, activities post DNA damage, and ATP-dependent processes during DNA synthesis. However, the impact of RFC complexes proteins on CRC prognosis remains unclear. To explore this, we employed a computational analysis approach, utilizing platforms such as the DepMap portal, GEPIA, DAVID Bioinformatics for KEGG pathway analysis, Human Protein Atlas (HPA), STRING, and TIMER. Our results indicate that the mRNA levels of RFC1 and RFC5 were the least expressed among CRC cell lines compared to other RFC complex subunits. Notably, low RFC1 and RFC5 expression was correlated with poor prognosis in terms of CRC patients' overall survival (OS). Immunohistochemical results from the Human Protein Atlas demonstrated medium staining for RFC1, RFC2, and RFC5 in CRC tissues. Furthermore, the low expression of RFC1 and RFC5 showed a significant correlation with high expression levels of miR-26a-5p and miR-636, impacting cell proliferation through mismatch repair, DNA replication, and the nucleotide excision repair pathway. Although the precise functions of RFC1 in cancer are still unknown, our findings suggest that the small-molecule single target, CHEMBL430483, and multiple target molecules could be potential treatments for CRC. In conclusion, the elevated expression of miR-26a-5p and miR-636 targeting RFC1 and RFC5 expression holds promise as a potential biomarker for early-stage CRC detection. These insights provide novel directions and strategies for CRC therapies.

circRNA-CPA4 Regulates Cell Proliferation and Apoptosis of Non-small Cell Lung Cancer via the miR-1183/PDPK1 Axis

Non-small-cell lung cancer (NSCLC) stands as a prevalent subtype of lung cancer, with circular RNAs emerging as key players in cancer development. This study elucidates the role of circRNA-CPA4 in NSCLC. Elevated circRNA-CPA4 expression in NSCLC lines was confirmed through qRT-PCR. Silencing circRNA-CPA4 with shRNA revealed, through CCK-8, colony formation, and flow cytometry assays, a notable constraint on proliferation and promotion of apoptosis in NSCLC cells. Subcellular localization analysis, RNA immunoprecipitation, and expression level assessments were employed to decipher the intricate interplay among miR-1183, circRNA-CPA4, and PDPK1. Results demonstrated heightened circRNA-CPA4 levels in NSCLC, and its knockdown curtailed NSCLC growth in vivo. Acting as a molecular sponge for miR-1183, circRNA-CPA4 regulated PDPK1 expression. Conversely, inhibiting miR-1183 counteracted the impact of circRNA-CPA4 silencing, reinstating NSCLC cell proliferation, and impeding apoptosis. Overall, this study unveils a novel mechanism: circRNA-CPA4 promotes PDPK1 expression by sequestering miR-1183, fostering NSCLC cell proliferation, and hindering apoptosis.

CircDENND2D Inhibits PD-L1-Mediated Non-Small Cell Lung Cancer Metastasis and Immune Escape by Regulating miR-130b-3p/STK11 Axis

Local recurrence and distant metastasis of non-small cell lung cancer (NSCLC) caused by immune escape is one of the root causes of treatment difficulties. We aim to investigate the mechanism of immune escape in NSCLC. NSCLC tissues were collected. Cell proliferation was detected by CCK-8 assay. Cell migration and invasion ability was measured by Transwell assay. The expressions of E-cadherin, N-cadherin and PD-L1 were detected by Western blot. NSCLC cells were co-cultured with CD8+ T cells to simulate tumor microenvironment in vitro. The proportion of CD8+ T cells and apoptosis were detected by flow cytometry. Dual-luciferase reporter gene assay confirmed the targeting relationship of circDENND2D and STK11. The expressions of circDENND2D and STK1 were down-regulated, while miR-130b-3p expression was up-regulated in NSCLC tissues. Overexpression of circDENND2D or STK11 inhibited NSCLC cells proliferation, migration and invasion, and attenuated the immune escape of NSCLC cells. CircDENND2D targeted miR-130b-3p to competitively promote STK11 expression. STK11 knockdown or miR-130b-3p overexpression attenuated the function of circDENND2D overexpression on NSCLC cells. CircDENND2D inhibited metastasis and immune escape of NSCLC by regulating miR-130b-3p/STK11 axis.

Exosomal circular RNA: a signature for lung cancer progression

Membrane vesicles having a diameter of 30-150 nm are known as exosomes. Several cancer types secrete exosomes, which may contain proteins, circular RNAs (circRNAs), microRNAs, or DNA. CircRNAs are endogenous RNAs that do not code for proteins and can create continuous and covalently closed loops. In cancer pathogenesis, especially metastasis, exosomal circRNAs (exo-circRNAs) have a crucial role mainly due to the frequently aberrant expression levels within tumors. However, neither the activities nor the regulatory mechanisms of exo-circRNAs in advancing lung cancer (LC) are obvious. A better understanding of the regulation and network connections of exo-circRNAs will lead to better treatment for LCs. The main objective of the current review is to highlight the functions and mechanisms of exo-circRNAs in LC and assess the relationships between exo-circRNA dysregulation and LC progression. In addition, underline the possible therapeutic targets based on exo-circRNA modulating.

Circ_0000808 promotes the development of non-small cell lung cancer by regulating glutamine metabolism via the miR-1827/SLC1A5 axis

Background

Circular RNA (circRNA) has been proved to be an important molecular target for cancer treatment. However, the function and molecular mechanism of circ_0000808 in non-small cell lung cancer (NSCLC) are still unclear.

Methods

Quantitative real-time PCR was used to detect the expression of circ_0000808, miR-1827, and solute carrier family 1 member 5 (SLC1A5). Cell proliferation, apoptosis, migration, and invasion were measured by cell counting kit 8 assay, colony formation assay, EdU staining, flow cytometry, wound healing assay, and transwell assay. The protein expression was measured by Western blot analysis. Dual-luciferase reporter assay and RIP assay were used to investigate the interactions between miR-1827 and circ_0000808 or SLC1A5. Cell glutamine metabolism was assessed by determining glutamine uptake, glutamate production, and α-ketoglutarate production. Xenograft mouse model was used to assess the in vivo effects of circ_0000808.

Results

Circ_0000808 expression was upregulated in NSCLC tissues and cancer cells, and its silencing inhibited NSCLC cell proliferation, migration, and invasion and led to apoptosis. Further results confirmed that circ_0000808 interacted with miR-1827 to positively regulate SLC1A5. The rescue experiments showed that miR-1827 inhibitor reversed the suppressive effect of circ_0000808 knockdown on the malignant behaviors of NSCLC cells. Also, SLC1A5 overexpression abolished the inhibition effect of miR-1827 on NSCLC cell progression. In addition, circ_0000808/miR-1827/SLC1A5 axis positively regulated the glutamine metabolism process in NSCLC cells. Moreover, circ_0000808 knockdown reduced the NSCLC tumor growth in vivo.

Conclusion

In summary, our data showed that circ_0000808 enhanced the progression of NSCLC by promoting glutamine metabolism through the miR-1827/SLC1A5 axis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12957-022-02777-x.

Identification of Novel miRNAs, Targeting Genes, Signaling Pathway, and the Small Molecule for Overcoming Oxaliplatin Resistance of Metastatic Colorectal Cancer

One of the globally common cancers is colorectal cancer (CRC). At present, a surgical approach remains a good option for CRC patients; however, 20% of surgically treated CRC patients experience metastasis. Currently, even the first-line used drug, oxaliplatin, remains inadequate for treating metastatic CRC, and its side effect of neurotoxicity is a major problem when treating CRC. The Gene Omnibus GSE42387 database contains gene expression profiles of parental and oxaliplatin-resistant LoVo cell lines. Differentially expressed genes (DEGs) between parental and oxaliplatin-resistance LoVo cells, protein-protein interactions (PPIs), and a pathway analysis were determined to identify overall biological changes by an online DAVID bioinformatics analysis. The ability of DEGs to predict overall survival (OS) and disease-free survival (DFS) was validated by the SPSS 22.0, using liver metastasis CRC patient samples of GSE41258. The bioinformatics web tools of the GEPIA, the Human Protein Atlas, WebGestalt, and TIMER platforms were used. In total, 218 DEGs were identified, among which 105 were downregulated and 113 were upregulated. After mapping the PPI networks and pathways, 60 DEGs were identified as hub genes (with high degrees). Six genes (TGFB1, CD36, THBS1, FABP1, PCK1, and IRS1) were involved with malaria, PPAR signaling, and the adipocytokine signaling pathway. High expressions of CD36 and PCK1 were associated with the poor survival of CRC patients in the GSE41258 database. We predicted specific micro (mi)RNAs that targeted the 3′ untranslated region (UTR) of PCK1 by using miRWalk. It was found that three miRNAs, viz., miR-7-5p, miR-20a-3p, and miR-636, may be upstream targets of those genes. High expression levels of miR-7-5p, miR-20a-3p, and miR-636 were associated with poor OS of CRC patients, and the small-molecule compound, mersalyl, is a promising drug for treating oxaliplatin-resistant CRC. In conclusion, miR-7-5p miR-20a-3p, and miR-636 targeted the PCK1 biomarker in the PPAR signaling pathway, which is involved in oxaliplatin-resistant CRC. Meanwhile, mersalyl was identified as a potential drug for overcoming oxaliplatin resistance in CRC. Our findings may provide novel directions and strategies for CRC therapies.

Biogenesis, functions, and clinical implications of circular RNAs in non-small cell lung cancer

Lung cancer (LC) is the leading cause of cancer-related deaths worldwide, with high morbidity and mortality. Non-small cell lung cancer (NSCLC) is a major pathological type of LC and accounts for more than 80% of all cases. Circular RNAs (circRNAs) are a large class of non-coding RNAs (ncRNAs) with covalently closed-loop structures, a high abundance, and tissue-specific expression patterns. They participate in various pathophysiological processes by regulating complex gene networks involved in proliferation, apoptosis, migration, and epithelial-to-mesenchymal transition (EMT), as well as metastasis. A growing number of studies have revealed that the dysregulation of circRNAs contributes to many aspects of cancer progression, such as its occurrence, metastasis, and recurrence, suggesting their great potential as efficient and specific biomarkers in the diagnosis, prognosis, and therapeutic targeting of NSCLC. In this review, we systematically elucidate the characteristics, biogenesis, and functions of circRNAs and focus on their molecular mechanisms in NSCLC progression. Moreover, we highlight their clinical implications in NSCLC treatment.

Circ_0010235 facilitates lung cancer development and immune escape by regulating miR-636/PDL1 axis

Background

Circular RNAs (circRNAs) are a class of important regulators in various human cancers, including lung cancer. Here, we aimed to investigate the role of circ_0010235 in lung cancer.

Methods

The expression of circ_0010235, microRNA‐636 (miR‐636) and PDL1 was measured by quantitative real‐time PCR (qRT‐PCR). Cell proliferation was evaluated by CCK‐8, colony formation, and 5‐ethynyl‐2′‐deoxyuridine (EdU) assays. Cell apoptosis was detected by flow cytometry. Cell invasion was assessed by transwell assay. All protein levels were determined by western blot assay. In order to detect the roles of circ_0010235 in immune escape, lung cancer cells were cocultured with peripheral blood mononuclear cells (PBMCs) or cytokine‐induced killer (CIK) cells in vitro. The relationship between miR‐636 and circ_0010235 or PDL1 was verified by dual‐luciferase reporter assay and RNA pulldown assay. Immunohistochemistry (IHC) analysis was used to detect Ki67 and programmed death‐ligand 1 (PDL1) expression. A xenograft tumor model was established to verify the function of circ_0010235 in vivo.

Results

Circ_0010235 was overexpressed in lung cancer. Circ_0010235 knockdown inhibited proliferation, invasion and immune escape and promoted apoptosis of lung cancer cells. MiR‐636 was a target of circ_0010235, and miR‐636 inhibition reversed the effects of circ_0010235 knockdown in lung cancer cells. PDL1 was a direct target of miR‐636, and miR‐636 suppressed the proliferation and invasion and increased apoptosis and antitumor immunity in lung cancer cells by downregulating PDL1. Moreover, circ_0010235 positively regulated PDL1 expression by sponging miR‐636. Additionally, circ_0010235 knockdown hampered tumorigenesis in vivo.

Conclusion

Circ_0010235 knockdown inhibited lung cancer progression and increased antitumor immunity by regulating the miR‐636/PDL1 axis.

Circ_0025039 acts an oncogenic role in the progression of non-small cell lung cancer through miR-636-dependent regulation of CORO1C

Non-small cell lung cancer remains the leading cause of cancer-related death worldwide. Circular RNA plays vital roles in NSCLC progression. This study is designed to reveal the role of circ_0025039 in NSCLC cell malignancy. The RNA expression of circ_0025039, microRNA-636 (miR-636), and coronin 1C was detected by quantitative real-time polymerase chain reaction. Protein expression was checked by Western blot analysis or immunohistochemistry assay. Cell proliferation, migration, invasion, tube formation ability, sphere formation capacity, and apoptosis were investigated by cell counting kit-8, 5-Ethynyl-29-deoxyuridine, transwell assay, tube formation assay, sphere formation assay, and flow cytometry analysis, respectively. Mouse model assay was conducted to reveal the effect of circ_0025039 silencing on tumor formation in vivo. The interaction between miR-636 and circ_0025039 or CORO1C was identified through dual-luciferase reporter and RNA pull-down assays. The expression of circ_0025039 and CORO1C was significantly increased, while miR-636 was decreased in NSCLC tissues and cells compared with controls. Circ_0025039 depletion repressed NSCLC cell proliferation, migration, invasion, tube-forming capacity, and sphere formation ability, but induced cell apoptosis. The neoplasm formation was repressed after circ_0025039 silencing. Additionally, circ_0025039 acted as a sponge for miR-636, which was found to target CORO1C. Importantly, the contribution of circ_0025039 to NSCLC progression was mediated by miR-636/CORO1C axis. Circ_0025039 silencing repressed NSCLC malignant progression by reducing CORO1C expression through miR-636, showing the possibility of circ_0025039 as a therapeutic target for NSCLC.

Hsa_circ_0007637 Facilitates Nasopharyngeal Carcinoma Progression by Sponging miR-636/TPD52 Axis

Purpose

Hsa_circ_0007637 was discovered to be differentially expressed in nasopharyngeal carcinoma (NPC). However, the exact function and mechanism of Hsa_circ_0007637 on NPC have not been studied. This study firstly researched the function and mechanism of Hsa_circ_0007637 on NPC progression.

Methods

Hsa_circ_0007637, miR-636 and TPD52 expressions in 80 NPC patients were detected by quantitative real-time polymerase chain reaction. Hsa_circ_0007637 effect on NPC cell proliferation, apopticosis, invasion and migration was investigated by cell counting kit-8 assay, flow cytometry, transwell experiment and wound healing assay accordingly. Dual-luciferase reporter gene assay, RNA immunoprecipitation experiment and RNA fluorescence in situ hybridization experiment were performed to identify the binding between Hsa_circ_0007637 and miR-636. Dual-luciferase reporter gene assay and RNA pull down assay were conducted to verify the binding between miR-636 and TPD52. TPD52 protein expression in NPC cells was determined by Western blot. In vivo study was performed using nude mice. Immunohistochemistry was performed to assess TPD52 and Ki67 expression in tissues.

Results

Hsa_circ_0007637 was overexpressed in NPC tissues and cells. High Hsa_circ_0007637 expression predicted a poor outcome for NPC patients. Hsa_circ_0007637 knockdown decreased proliferation, invasion, migration and increased apoptosis of NPC cells (P < 0.01). Hsa_circ_0007637 could enhance TPD52 expression via sponging miR-636. miR-636 overexpression or TPD52 knockdown weakened the promoting effect of Hsa_circ_0007637 on NPC cells malignant phenotype (P < 0.01). Hsa_circ_0007637 knockdown suppressed NPC cells growth in vivo (P < 0.01).

Conclusion

Hsa_circ_0007637 facilitates NPC progression by sponging miR-636/TPD52 axis.

Circ_0017639 facilitates proliferative, migratory, and invasive potential of non-small cell lung cancer (NSCLC) cells via PI3K/AKT signaling pathway

Non-small cell lung cancer (NSCLC) has increased morbidity and mortality rate worldwide. The current NSCLS therapies are associated with poor outcomes and need further improvement. CircRNAs were shown to regulate NSCLC progression. However, little is known re garding the functions and mechanisms of circ_0017639 in NSCLC, which requires further extensive studies. The circ_0017639 expression in NSCLC tissues and cell lines was evaluated via qRT-RCR. Moreover, using ectopic plasmid incorporation and shRNA assays, we analyzed the circ_0017639-mediated cellular proliferative, migratory and invasive processes in NSCLC cell lines, using CCK-8, EdU, and transwell assays. Furthermore, the core proteins (p-PI3K, PI3K, p-AKT, and AKT) levels of the PI3K/AKT signaling cascade were investigated via immunoblotting. Finally, we tested the functional role of circ_0017639 by examining its regulation of xenograft tumor growths in nude mice in vivo. Circ_0017639 expression was remarkably high in the NSCLC tissues and cell lines. The transfection experiments showed that circ_0017639 overexpression was able to promote proliferative, migratory, and invasive properties of NSCLC cells, while sh-circ_0017639 showed opposing effects. We further showed that circ_0017639 knockdown suppressed the cellular development via PI3K/AKT cascade inactivation. Additionally, in-vivo experiment in nude mice demonstrated that sh-circ_0017639 could reduce the tumor growth of NSCLC. Circ_0017639 may promote the development of NSCLC by accelerating NSCLC metastasis through stimulating the PI3K/AKT cascade.

Circular RNA circ_0023404 serves as a miR-636 sponge to promote malignant behaviors in cervical cancer cells through upregulation of CYP2S1

Cervical cancer is the most common malignant gynecological tumor. Circular RNA (circRNA) circ_0023404 is reported to be upregulated in cervical cancer cells. This aim is to explore the role and mechanism of circ_0023404 in cervical cancer. circ_0023404, microRNA-636 (miR-636), and cytochrome P450 2S1 (CYP2S1) levels were detected by real-time quantitative polymerase chain reaction (RT-qPCR). Cell proliferation, migration, invasion, and apoptosis were detected by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) assay, 5-ethynyl-2'-deoxyuridine (EDU) assay, colony formation assay, transwell assay, and cytometry assay. Protein levels of cyclin D1, matrix metallopeptidase 9 (MMP9), Bcl-2-associated X protein (Bax), and CYP2S1 were examined by western blot assay. The binding relationship between miR-636 and circ_0023404 or CYP2S1 was predicted by Circinteractome or targetscan, and then verified by a dual-luciferase reporter assay and RNA pull-down assay. circ_0023404 and CYP2S1 expression were increased, and miR-636 was decreased in cervical cancer tissues and cells. Moreover, circ_0023404 knockdown could repress proliferation, migration, invasion, and promote apoptosis of cervical cancer cells in vitro. Mechanically, circ_0023404 could regulate CYP2S1 expression by sponging miR-636. circ_0023404 silencing could attenuate the progression of cervical cancer cells partly by targeting the miR-636/CYP2S1 axis, hinting at a promising therapeutic target for cervical cancer.

CircRPPH1 promotes cell proliferation, migration and invasion of non-small cell lung cancer (NSCLC) via the PI3K/AKT and JAK2/STAT3 signaling axes

Non-small cell lung cancer (NSCLC) has markedly increased morbidity and mortality rate worldwide. Circular RNAs (circRNAs) were shown to regulate NSCLC progression. But, the underlying pathways of the circRPPH1-mediated regulation of NSCLC still need further exploration. We evaluated circRPPH1 levels in NSCLC tissues and cell lines via qRT-RCR. Moreover, using ectopic plasmid incorporation and siRNA assays, we analyzed the circRPPH1-mediated regulation of cell proliferation (CP), migration (CM), and invasion (CI) in NSCLC cell lines (H1975 and A549 cells), using CCK-8, colony forming, scratch wound, and transwell assays, respectively. CircRPPH1 levels were remarkably high in the NSCLC tissues and cell lines. The transfection experiments showed that circRPPH1 overexpression was able to promote CP, CM and CI of NSCLC cells, while CP, CM and CI were significantly restrained by the knockdown of circRPPH1. We also displayed that circRPPH1 knockdown suppressed the cell progression via inactivating the PI3K/AKT and JAK2/STAT3 signaling axes. Subsequently, in vivo experiment in nude mice was demonstrated that the inhibition of circRPPH1 could reduce the tumor growth of NSCLC. circRPPH1 may accelerate the growth and metastasis of NSCLC, in culture conditions and in animal models, by stimulating the PI3K/AKT and JAK2/STAT3 signaling axes, thus promoting the development of NSCLC.

Crosstalk between circRNAs and the PI3K/AKT signaling pathway in cancer progression

Circular RNAs (circRNAs), covalently closed noncoding RNAs, are widely expressed in eukaryotes and viruses. They can function by regulating target gene expression, linear RNA transcription and protein generation. The phosphoinositide 3-kinase (PI3K)/AKT signaling pathway plays key roles in many biological and cellular processes, such as cell proliferation, growth, invasion, migration, and angiogenesis. It also plays a pivotal role in cancer progression. Emerging data suggest that the circRNA/PI3K/AKT axis modulates the expression of cancer-associated genes and thus regulates tumor progression. Aberrant regulation of the expression of circRNAs in the circRNA/PI3K/AKT axis is significantly associated with clinicopathological characteristics and plays an important role in the regulation of biological functions. In this review, we summarized the expression and biological functions of PI3K-AKT-related circRNAs in vitro and in vivo and assessed their associations with clinicopathological characteristics. We also further discussed the important role of circRNAs in the diagnosis, prognostication, and treatment of cancers.