RHPN1-AS1 promotes cell proliferation and migration via miR-665/Akt3 in ovarian cancer

The Multifunctional Nature of the MicroRNA/AKT3 Regulatory Axis in Human Cancers

Serine/threonine kinase (AKT) signaling regulates diverse cellular processes and is one of the most important aberrant cell survival mechanisms associated with tumorigenesis, metastasis, and chemoresistance. Targeting AKT has become an effective therapeutic strategy for the treatment of many cancers. AKT3 (PKBγ), the least studied isoform of the AKT family, has emerged as a major contributor to malignancy. AKT3 is frequently overexpressed in human cancers, and many regulatory oncogenic or tumor suppressor small non-coding RNAs (ncRNAs), including microRNAs (miRNAs), have recently been identified to be involved in regulating AKT3 expression. Therefore, a better understanding of regulatory miRNA/AKT3 networks may reveal novel biomarkers for the diagnosis of patients with cancer and may provide invaluable information for developing more effective therapeutic strategies. The aim of this review was to summarize current research progress in the isoform-specific functions of AKT3 in human cancers and the roles of dysregulated miRNA/AKT3 in specific types of human cancers.

Hsa-miR-665 Is a Promising Biomarker in Cancer Prognosis

Biomarkers are biomolecules used to identify or predict the presence of a specific disease or condition. They play an important role in early diagnosis and may be crucial for treatment. MicroRNAs (miRNAs), a group of small non-coding RNAs, are more and more regarded as promising biomarkers for several reasons. Dysregulation of miRNAs has been linked with development of several diseases, including many different types of cancer, and abnormal levels can be present in early stages of tumor development. Because miRNAs are stable molecules secreted and freely circulating in blood and urine, they can be sampled with little or no invasion. Here, we present an overview of the current literature, focusing on the types of cancers for which dysregulation of miR-665 has been associated with disease progression, recurrence, and/or prognosis. It needs to be emphasized that the role of miR-665 sometimes seems ambiguous, in the sense that it can be upregulated in one cancer type and downregulated in another and can even change during the progression of the same cancer. Caution is thus needed before using miR-665 as a biomarker, and extrapolation between different cancer types is not advisable. Moreover, more detailed understanding of the different roles of miR-665 will help in determining its potential as a diagnostic and prognostic biomarker.

Roles, biological functions, and clinical significances of RHPN1-AS1 in cancer

For the complex and multifaceted challenge of cancer eradication, a comprehensive approach is required. Molecular strategies are critical in the fight against cancer as they allow us to understand the underlying fundamental mechanisms and develop specialized treatments. The role of long non-coding RNAs (lncRNAs), a class of ncRNA molecules longer than 200 nucleotides, in cancer biology has attracted growing attention in recent years. These roles include but are not limited to regulating gene expression, protein localization, and chromatin remodeling. LncRNAs can influence a range of cellular functions and pathways, including those involved in cancer development. The first study on RHPN1 antisense RNA 1 (RHPN1-AS1), a 2030-bp transcript originating from human chromosome 8q24, in uveal melanoma (UM) demonstrated that this lncRNA was significantly upregulated in several UM cell lines. Further studies in various cancer cell lines showed that this lncRNA is significantly overexpressed and exerts oncogenic functions. This review will provide an overview of current knowledge regarding the roles played by RHPN1-AS1 in the emergence of various cancers, focusing on its biological and clinical functions.

Identification of lncRNAs Deregulated in Epithelial Ovarian Cancer Based on a Gene Expression Profiling Meta-Analysis

Epithelial ovarian cancer (EOC) is one of the deadliest gynecological cancers worldwide, mainly because of its initially asymptomatic nature and consequently late diagnosis. Long non-coding RNAs (lncRNA) are non-coding transcripts of more than 200 nucleotides, whose deregulation is involved in pathologies such as EOC, and are therefore envisaged as future biomarkers. We present a meta-analysis of available gene expression profiling (microarray and RNA sequencing) studies from EOC patients to identify lncRNA genes with diagnostic and prognostic value. In this meta-analysis, we include 46 independent cohorts, along with available expression profiling data from EOC cell lines. Differential expression analyses were conducted to identify those lncRNAs that are deregulated in (i) EOC versus healthy ovary tissue, (ii) unfavorable versus more favorable prognosis, (iii) metastatic versus primary tumors, (iv) chemoresistant versus chemosensitive EOC, and (v) correlation to specific histological subtypes of EOC. From the results of this meta-analysis, we established a panel of lncRNAs that are highly correlated with EOC. The panel includes several lncRNAs that are already known and even functionally characterized in EOC, but also lncRNAs that have not been previously correlated with this cancer, and which are discussed in relation to their putative role in EOC and their potential use as clinically relevant tools.

Hsa_circ_0129047 sponges miR-665 to attenuate lung adenocarcinoma progression by upregulating protein tyrosine phosphatase receptor type B

Compelling evidence has demonstrated the critical role of circular RNAs (circRNAs) during lung adenocarcinoma (LUAD) progression. Herein, we explored a novel circRNA, circ_0129047, and detailed its mechanism of action. The expression of circ 0129047, microRNA-665 (miR-665), and protein tyrosine phosphatase receptor type B (PTPRB) in LUAD tissues and cells was determined using reverse transcription quantitative polymerase chain reaction and Western blotting. Cell Counting Kit-8 and colony formation assays were conducted to detect LUAD cell proliferation, and western blotting was performed to quantify apoptosis-related proteins (Bcl-2 and Bax). Luciferase reporter and RNA immunoprecipitation assays were used to validate the predicted interaction between miR-665 and circ_0129047 or PTPRB. A xenograft assay was used for the in vivo experiments. Circ_0129047 and PTPRB were downregulated in LUAD tissues and cells, whereas miR-665 expression was upregulated. Overexpression of circ_0129047 suppresses LUAD growth in vivo and in vitro. Circ_0129047 is the target of miR-665, and the miR-665 mimic ablated the antiproliferative and pro-apoptotic phenotypes of LUAD cells by circ_0129047 augmentation. MiR-665 targets the 3'UTR of PTPRB and downregulates PTPRB expression. PTPRB overexpression offsets the pro-proliferative potential of miR-665 in LUAD cells. Circ_0129047 sequestered miR-665 and upregulated PTPRB expression, thereby reducing LUAD progression, suggesting a promising approach for preventing LUAD.

Pseudo-sapogenin DQ 3-mimaleate acid derivative induces ovarian carcinoma cell apoptosis via mitochondrial pathway

In the present study, four novel ginsenosides fatty acid and aromatic acid derivatives were designed and synthesized, and their cytotoxic effects on human ovarian carcinoma cells (SKOV3) were assessed using the MTT assay. The results demonstrated that all derivatives inhibited SKOV3 cell growth, and Compound 3 showed the most outstanding anti-proliferative effect on SKOV3 cells. The IC₅₀ value of Compound 3 was 33.8 ± 2.21 μM, less than half of that of cis-platinum (70.1 ± 7.64 μM). Subsequent analysis revealed that Compound 3 could promote SKOV3 cell apoptosis, and the percentage of apoptotic cell population increased with increasing Compound 3 concentrations. In addition, the expression ratios of Bax/Bcl-2, cleaved-Caspase-3/Caspase-3 and cleaved-Caspase-9/Caspase-9 were gradually elevated in Compound 3-treated SKOV3 cells compared with control cells. Furthermore, translocation of Bax to mitochondria was associated with the release of Cytochrome C. Molecular docking analysis revealed three hydrogen-bonds existed in Compound 3 with PARP receptor (PDB code: 5DSY), which may be the target of the anti-ovarian cancer effect of Compound 3. Altogether, our study indicates that Compound 3 induces SKOV3 cell apoptosis via ROS-dependent mitochondrial pathway, and can serve as an anti-cancer agent for treating ovarian carcinoma.

LncRNA RPSAP52 promotes cell proliferation and inhibits cell apoptosis via modulating miR-665/STAT3 in gastric cancer

LncRNA RPSAP52 is a newly identified functional molecular in several cancers, but its role in gastric cancer (GC) is currently unclear. This study aimed to investigate the biofunction of lncRNA RPSAP52 in GC. Quantitative polymerase-chain reaction (RT-qPCR) was employed to analyze the gene level of lncRNA RPSAP52 and miR-665. Cell proliferation capacity was evaluated via CCK-8 and colony formation assay. Flow cytometry was applied to detect cell cycle and cell apoptosis. Hematoxylin-eosin staining was conducted for histopathological analysis. Immunochemical staining was carried out to detect expression level of ki-67. Subcellular fractionation was performed to explore the position of lncRNA RPSAP52. The binding relationship among lncRNA RPSAP52, miR-665 and STAT3 was verified via luciferase reporter assay. RNA pull down experiments were used to verify the binding relationship between lncRNA RPSAP52 and miR-665. The STAT3 level was evaluated via Western blot. LncRNA RPSAP52 is significantly elevated in GC cells. Deletion of lncRNA RPSAP52 restrained cell proliferation and induced G0-G1 phase arrest, while expediting apoptosis in GC cells. Tumor growth in vivo was suppressed following lncRNA RPSAP52 depletion. MiR-665 was verified as the target of lncRNA RPSAP52. A ceRNA-sponge mechanism of lncRNA RPSAP52 on miR-665 was identified. Meanwhile, miR-665 functions as STAT3 sponge. MiR-665 overexpression and STAT3 depletion served the same functions as lncRNA RPSAP52 depletion in GC cells. LncRNA RPSAP52 exerted anti-cancer effects via modulating miR-665/STAT3 in GC.Abbreviations: Gastric cancer (GC); Quantitative polymerase-chain reaction (RT-qPCR); Helicobacter pylori (H. pylori); Roswell Park Memorial Institute 1640 (RPMI 1640); fetal bovine serum (FBS); glyceraldheyde 3-phosphate dehydrogenase (GAPDH); propidium iodide (PI); Cell counting kit-8 (CCK-8); radioimmunoprecipitation assay (RIPA); sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE); polyvinylidene fluoride (PVDF); enhanced chemiluminescence (ECL); Statistical Product and Service Solutions (SPSS); standard deviation (SD).

Integrated analysis of 1804 samples of six centers to construct and validate a robust immune-related prognostic signature associated with stromal cell abundance in tumor microenvironment for gastric cancer

Background

Stromal cells in tumor microenvironment could promote immune escape through a variety of mechanisms, but there are lacking research in the field of gastric cancer (GC).

Methods

We identified differential expressed immune-related genes (DEIRGs) between the high- and low-stromal cell abundance GC samples in The Cancer Genome Atlas and GSE84437 datasets. A risk score was constructed basing on univariate cox regression analysis, LASSO regression analysis, and multivariate cox regression analysis in the training cohort (n=772). The median value of the risk score was used to classify patients into groups with high and low risk. We conducted external validation of the prognostic signature in four independent cohorts (GSE26253, n=432; GSE62254, n=300; GSE15459, n=191; GSE26901, n=109) from the Gene Expression Omnibus (GEO) database. The immune cell infiltration was quantified by the CIBERSORT method.

Results

The risk score contained 6 genes (AKT3, APOD, FAM19A5, LTBP3, NOV, and NOX4) showed good performance in predicting 5-year overall survival (OS) rate and 5-year recurrence-free survival (RFS) rate of GC patients. The risk death and recurrence of GC patients growing with the increasing risk score. The patients were clustered into three subtypes according to the infiltration of 22 kinds of immune cells quantified by the CIBERSORT method. The proportion of cluster A with the worst prognosis in the high-risk group was significantly higher than that in the low-risk group; the risk score of cluster C subtype with the best prognosis was significantly lower than that of the other two subtypes.

Conclusion

This study established and validated a robust prognostic model for gastric cancer by integrated analysis 1804 samples of six centers, and its mechanism was explored in combination with immune cell infiltration characterization.

Hypomethylation-driven AKT Serine/Threonine Kinase 3 promotes testicular germ cell tumors proliferation and negatively correlates to immune infiltration

AKT Serine/Threonine Kinase 3 (AKT3) has been reported to play an important role in different tumors. However, its clinical value, biological function, and molecular mechanism in testicular germ cell tumors (TGCT) remains unclear. In the current study, we applied the Gene Set Cancer Analysis (GSCA), UCSC XENA, Gene Expression Omnibus (GEO), the Human Protein Atlas (HPA), LinkedOmics, DiseaseMeth version 2.0, TISIDB, and other databases for TGCT data mining. Then, we investigated AKT3’s mechanism of action and clinical survival significance via bioinformatics followed by in vitro experiments. We found that AKT3 was upregulated and had frequent copy number amplifications in TGCT, which were associated with poor survival outcomes of patients. On the other hand, mutations that led to AKT3 loss-of-function were correlated to a better prognosis in patients. Moreover, AKT3 silencing significantly inhibited the proliferation, DNA synthesis and colony formation of NCCIT cells (a TGCT cell line). AKT3 might participate in TGCT progression through multiple signaling pathways, such as ErbB, oxidative phosphorylation, and affecting tumor immune infiltration. Also, the upregulation of AKT3 mRNA expression might be driven by the hypomethylation of its promoter region. Overall, AKT3 is a potential TGCT oncogene and can be further used as a therapeutic target.

Rhophilin rho GTPase binding protein 1-antisense RNA 1 (RHPN1-AS1) promotes ovarian carcinogenesis by sponging microRNA-485-5p and releasing DNA topoisomerase II alpha (TOP2A)

Ovarian cancer (OC) is the most common and lethal gynecological cancer worldwide. Long non-coding RNAs (lncRNAs) and sponging microRNAs (miRNAs) serve as key regulators in the biological processes of OC. We sought to evaluate the effect of the RHPN1-AS1-miR-485-5p-DNA topoisomerase II alpha (TOP2A) axis in regulating OC progression. RHPN1-AS1, miR-485-5p, and TOP2A levels in OC tissues and cells were determined by RT-qPCR. The interaction of RHPN1-AS1/miR-485-5p/TOP2A was assessed using luciferase, RNA immunoprecipitation, and RNA pull-down assays. RHPN1-AS1 silencing allowed us to explore its biological function by measuring cell viability, proliferation, migration, invasion, and apoptosis in OC cells. In vivo experiments were performed to verify the in vitro findings. We found that the RHPN1-AS1 and TOP2A levels were significantly enhanced, whereas the miR-485-5p levels were reduced in OC tissues and cells. RHPN1-AS1 silencing attenuated cell growth, facilitated apoptosis in OC cells, and inhibited tumor growth in vivo. Notably, RHPN1-AS1 negatively regulating miR-485-5p promoted the TOP2A expression in OC cells. In conclusion, RHPN1-AS1 sponging miR-485-5p accelerated the progression of OC by elevating TOP2A expression, which makes it a promising target for the treatment of OC patients.

AGTR1 Inhibits the Progression of Lung Adenocarcinoma

Purpose

The occurrence and development of lung adenocarcinoma (LUAD) are related to many factors. Multiple researches showed that the renin-angiotensin system (RAS) plays an important role in lung cancer. This research mainly focuses on angiotensin II receptor 1 (AT1R) encoding gene AGTR1, an important part of the RAS.

Methods

We comprehensively evaluated the expression of AGTR1 in pan-cancer based on RNA sequencing data obtained from The Cancer Genome Atlas (TCGA). We explored the correlation of AGTR1 with clinicopathological features, prognosis and tumor microenvironment in LUAD. We also explored the mechanism through enrichment analysis and verified it with cell lines and tissue samples.

Results

We found that AGTR1 was less expressed in most tumors and related to prognosis based on the TCGA database. To further explore its mechanism, we mainly focused on LUAD. Combined with the verification results in the GEO database, AGTR1 was associated with a better prognosis in LUAD. High expression of AGTR1 was associated with less lymph node metastasis (P=0.007) and MET mutation (P=0.019). High expression of AGTR1 was related to the anti-tumor immune microenvironment with high infiltration of B cells, myeloid dendritic cells, monocytes, and low infiltration of myeloid-derived suppressor cells (all P<0.05). Enrichment analysis and in vitro verification results showed that AGTR1 was likely to play a role in LUAD through the PI3K/AKT3 pathway. Finally, we verified the above results through tissue samples and the construction of AGTR1 overexpressing cells.

Conclusion

AGTR1 inhibits the progression of lung adenocarcinoma through the PI3K/AKT3 pathway.

Downregulation of MIAT reduces the proliferation and migratory and invasive abilities of retinoblastoma cells by sponging miR-665 and regulating LASP1

Long non-coding RNAs (lncRNAs) can function as onco-lncRNAs in several types of human cancer, including retinoblastoma (Rb). The present study investigated the potential role and regulatory mechanism of the lncRNA myocardial infarction-associated transcript (MIAT) in Rb. To do so, the expression levels of MIAT, microRNA (miR)-665, and LIM and SH3 protein 1 (LASP1) in Rb tissues from patients or Rb cells were analysed using reverse transcription quantitative PCR. The interactions between miR-665 and MIAT/LASP1 were confirmed by the dual-luciferase reporter assay. MTT, Transwell (to assess migration and invasion) and western blotting assays were used to explore the functions of the MIAT/miR-665/LASP1 axis on Rb progression in vitro. The results of the present study indicated that MIAT targeted miR-665. In Rb tissues and cell lines, high expression of MIAT was observed, whereas miR-665 was downregulated in Rb tissues. Furthermore, the proliferation and migratory and invasive abilities of Rb Y79 and HXO-RB44 cells were decreased following MIAT downregulation or miR-665 overexpression. In addition, LASP1 was identified as a target gene of miR-665. Both the decreased expression of miR-665 and the elevated expression of LASP1 reversed the suppressive effects of MIAT knockdown on the proliferation and migratory and invasive abilities of Y79 cells. Furthermore, MIAT silencing attenuated the development of Rb by regulating the miR-665/LASP1 axis. Taken together, these findings suggested that MIAT may be considered as a possible therapeutic target for Rb.

MicroRNA-33b replacement effect on growth and migration inhibition in ovarian cancer cells

PURPOSE

Ovarian cancer is a devastating gynecological disease which is considered the major cause of cancer fatality around the world. The down-regulation of microRNA-33b (miR-33b) was reported in some malignancies. Hence, we transfected the miR-33b mimic into SKOV3 cells and evaluated the impacts of this interference on the growth and migration repression of these tumor cells as well as on targeted genes expression.

METHODS

In our study, transfecting the miR-33b mimic and inhibitor, negative control (NC), and NC inhibitor were established using Lipofectamine 2000. The cytotoxic effects of miR-33b were evaluated by MTT. To assess the miR-33b effects on cell migration, a scratching test was applied. The expression levels of miR-33b, ADAMTS, C-Myc, MMP9, K-Ras, and CXCR4 were evaluated using qRT-PCR.

RESULTS

These findings indicate that transfection of miR-143 mimic had no marked effects on the SKOV3 cell line. As expected, miR-33b relative expression levels were as follows: miR-33b mimic >NC and NC inhibitor >miR-33b inhibitor (p < 0.01). Moreover, transfected miR-33b mimic could suppress SKOV3 cells' proliferation, whereas transfected miR-33b inhibitor could promote cell proliferation (p < 0.01). MiR-33b overexpression significantly down-regulated the MMP9, CXCR-4, c-Myc, ADAMTS, and K-Ras mRNA levels (p < 0.05).

CONCLUSION

As expected, these results confirm the tumor-suppressive effect of miR-33b in the SKOV3 ovarian cancer cell line by reducing cell survival, proliferation, and migration.

RHPN1‑AS1 promotes ovarian carcinogenesis by sponging miR‑6884‑5p thus releasing TOP2A mRNA

Ovarian cancer, a severe lethal gynecological malignancy, is characterized by both high morbidity and mortality. Long noncoding RNAs (lncRNAs) have recently caused extensive concern due to their regulatory function in various human tumors. There are a mounting number of lncRNAs that are in extreme need of research, serving as biomarkers for diagnosis and therapy for ovarian cancer. In the present study, RT-qPCR was employed to detect how Rhophilin Rho GTPase binding protein 1 antisense RNA1 (RHPN1-AS1), miR-6884-5p and DNA topoisomerase IIα (TOP2A) are expressed in ovarian cancer tissues or cell lines. BrdU, MTT, colony formation and cell adhesion assays, caspase-3 activity, flow cytometry and wound healing assay were employed to assess cell proliferation, viability, colony number, adhesion, apoptosis and migration in ovarian cancer, respectively. RHPN1-AS1 was determined to be enriched in ovarian cancer tissues and cell lines. Silencing of RHPN1-AS1 was reported to increase cell apoptosis and impair cell proliferation, viability, colony number, adhesion and migration in vitro. Furthermore, RHPN1-AS1 was able to sponge miR-6884-5p which directly targets TOP2A in ovarian cancer. Notably, silencing of RHPN1-AS1 functionally reversed the oncogenic effect induced by the miR-6884-5p inhibitor, while the miR-6884-5p inhibitor markedly restored the inhibition of ovarian carcinogenesis modulated by silencing TOP2A in ovarian cancer. RHPN1-AS1 was found to promote ovarian carcinogenesis via sponging miR-6884-5p thus releasing TOP2A, and RHPN1-AS1 may act as a promising biomarker for the prognosis and therapy of ovarian cancer.

RHPN1‑AS1 promotes ovarian carcinogenesis by sponging miR‑485‑5p and releasing TPX2 mRNA

Long non-coding RNAs (lncRNAs) play a crucial role in cancer development. However, researchers have yet to identify the underlying association between lncRNAs and ovarian cancer (OC). The aim of the present study was to examine the effect of lncRNA RHPN1-AS1 (RHPN1-AS1) on OC cells and tissues. Reverse transcriptase-quantitative PCR (RT-qPCR) was utilized to quantify RHPN1-AS1, miR-485-5p, and TPX2 mRNA expression in samples with OC. Luciferase-reporter assay, RNA immunoprecipitation (RIP) assay, and RNA pull-down assay were then employed to validate the target relationship among RHPN1-AS1, miR-485-5p and TPX2. Cell Counting Kit-8, BrdU, wound-healing, cell-adhesion, and flow cytometry assays were also employed to assess cell viability, proliferation, migration, adhesion and apoptosis, respectively, in SKOV3 and OVCAR3 cell lines. Findings revealed that RHPN1-AS1 demonstrated a higher expression level in OC cell lines and tissues. In addition, RHPN1-AS1 enhanced the adhesion, proliferation and migration of OC cell lines but decreased apoptosis of OC cells. It was also observed that the relationship between RHPN1-AS1 and miR-485-5p was negative and that RHPN1-AS1 could sponge miR-485-5p to regulate the proliferation, apoptosis, adhesion, and migration abilities of OC cells. Moreover, TPX2 was targeted by miR-485-5p and was significantly overexpressed in OC cell lines and tissues. Experimental investigations also revealed that TPX2 promoted the proliferation, adhesion, and migration of OC cells but suppressed the apoptosis of SKOV3 and OVCAR3 cells. In summary, RHPN1-AS1 played a tumor promotive role by sponging miR-485-5p to increase TPX2 expression in OC tumorigenesis.

MicroRNA-665 regulates the proliferation, apoptosis and adhesion of gastric cancer cells by binding to cadherin 3

Numerous studies have reported that abnormal cadherin 3 (CDH3) and microRNA (miRNA/miR)-665 expression can induce the progression of gastric cancer (GC). However, the mechanism of interaction between miR-665 and CDH3 in GC requires further investigation. The present study aimed to investigate the influence of miR-665 and CDH3 in GC development. The effect of miR-665 and CDH3 on GC tissues and cell lines was examined using reverse transcription-quantitative PCR. Subsequently, CDH3 protein expression in GC cell lines was detected using western blotting. To confirm the association between miR-665 and CDH3, a dual-luciferase reporter assay system was employed. Cell proliferation and adhesion were analyzed using BrdU ELISA, MTT and cell adhesion assays. Finally, caspase-3 activity assay kit and FITC apoptosis detection kit were used for the determination of apoptosis of GC cells. The current findings confirmed the upregulation of CDH3 expression in GC cell lines and tissues. Experimental results indicated that CDH3 overexpression increased cell proliferation and adhesion, but decreased the apoptosis level of the cells. Similarly, the miR-665 inhibitor enhanced cell proliferation and adhesion, but inhibited apoptosis of GC cells. Additionally, it was observed that CDH3 was a direct target of miR-665 in GC cells and that miR-665 inhibited CDH3 expression, thereby repressing the progression of GC. In conclusion, the present study suggested that by targeting CDH3, miR-665 suppressed the progression of GC. These findings may provide a significant theoretical basis for future GC clinical therapy.

Silencing long non-coding RNA CASC9 inhibits colorectal cancer cell proliferation by acting as a competing endogenous RNA of miR-576-5p to regulate AKT3

Increasing studies have shown that long non-coding RNAs (lncRNAs) are regarded as important regulators in the occurrence and development of colorectal cancer (CRC). Although lncRNA CASC9 has been studied in CRC, the detailed regulatory mechanism of CASC9 in CRC is still unclear. In this study, we found that CASC9 was significantly upregulated in CRC tissues and cell lines compared to normal controls and that aberrant expression was associated with the tumor-node-metastasis (TNM) stage of CRC. Functionally, CASC9 depletion efficiently inhibited the proliferation of CRC cells and induced cell apoptosis in vitro. Mechanistically, CASC9 was mainly enriched in the cytoplasm of CRC cells and interacted directly with miR-576-5p. Downregulation of miR-576-5p reversed the inhibitory effect of CASC9 siRNA on CRC cell progression. Furthermore, AKT3 has been identified as a downstream target of miR-576-5p. Spearman’s correlation analysis revealed that AKT3 was negatively correlated with miR-576-5p but positively correlated with CASC9. Downregulation of miR-576-5p restored the effect of CASC9 silencing on AKT3 expression. Therefore, silencing CASC9 could downregulate the expression of AKT3 by reducing the competitive binding of CASC9 to miR-576-5p, thus suppressing CRC cell proliferation and promoting cell apoptosis. In summary, we identified CASC9 as an oncogenic lncRNA in CRC and defined the CASC9/miR-576-5p/AKT3 axis, which might be considered a potential therapeutic target for CRC patients, as a novel molecular mechanism implicated in the proliferation and apoptosis of CRC.