# MiR-223 Promotes Tumor Progression via Targeting RhoB in Gastric Cancer

Authors: You Hu; Bin Yi; Xin Chen; Lu Xu; Xiaojun Zhou; Xinguo Zhu
Journal: Journal of Oncology
 (2022)

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## Abstract

Gastric cancer (GC) is among the most prevalent causes of cancer-related death globally. MiR-223 has been implicated in a variety of cellular mechanisms linked to cancer progression. However, the miR-223 expressions and its function in GC are unknown. We discovered that miR-223 expression was raised in GC tissues in comparison with nearby normal tissues in this investigation. Additionally, multiplied miR-223 expression was strongly linked with TNM stage (p=0.022), live metastasis (p=0.004),lymph node metastasis (p=0.004),and Borrmann type and was associated with an unfavorable prognostic for patients with GC. Furthermore, suppressing miR-223 significantly increased cell death and prevented cell migration and invasion in vitro. Additionally, miR-223 silencing decreased tumor development in vivo. Additionally, we discovered that miR-223 enhanced GC development by specifically targeting RhoB. In summary, our findings reveal that miR-223 increases tumor progression in GC by targeting RhoB, suggesting that it could serve to be a potential biomarker for the prediction of the disease.


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## Body

## 1. Introduction

Gastric cancer (GC) has been one of the prominent reasons of cancer death around the globe [1]. Although there are substantial advances in the detection and treatment of human malignancies, patients with GC continue to have a dismal prognosis [2]. As a result, it is useful to identify critical genes and to investigate the molecular mechanisms that underlie important genes that are involved in GC formation.MicroRNAs (miRNAs) are a family of noncoding RNA molecules that are small (17–22 nucleotides) and have been shown to have a posttranscriptional regulatory function [3]. MiRNAs are implicated in the progression of a wide range of human malignancies, according to numerous studies [4]. For example, Feliciano et al. discovered that miR-99a through the EMT process inhibited the transition of epithelial cells concurrently with the reduction of stemness characteristics in lung cancer by decreasing E2F2 and EMR2 [5]. By directly inhibiting the TUSC3-mediated AKT pathway, miR-873-5p reduced colon cancer progression [6]. MiR-4458, which targets CPSF4 in breast cancer cells, has proven to reduce cancer cell propagation, migration, and invasiveness [7]. Wu et al. demonstrated that elevated miR-135b expression may predispose GC8 to malignant transformation and poor prognosis [8]. These findings established that miRNAs have had a pivotal role in cancer progression.MiR-223, a critical cancer-related miRNA, has been shown to be linked in a wide range of biological events associated with cancer progression [9]. Zhou et al. showed that miR-223/FBXW7 signaling had been critical for human GC cell cisplatin resistance [10]. MiR-223, which targets PDS5B, was noticed to influence the normal cell propagation and invasion in pancreatic cancer [11]. According to Zhou et al., through targeting FOXO3a, doxorubicin-stimulated autophagy was suppressed by overexpression of miR-223 and restored the resistance against chemotherapy in hepatocellular carcinoma cells [12]. In luminal breast cancer, knocking down miR-223 caused resistance against CDK4/6 inhibitors [13]. These investigations revealed that, in the progression of numerous cancers, miR-223 plays a vital role. However, the mechanism by which miR-223 acts in GC is unclear.Therefore, this research aims to examine the miR-223 expression in GC and healthy tissues, as well as interdependency among the expression of miR-223, clinicopathological characteristics, and prognosis of GC patients. Functionality and the mechanism of miR-223 on GC development were then explored in vitro and in vivo, with the goal of developing a molecular prognostic biomarker for GC.


## 2. Materials and Methods

### 2.1. Tissue Samples

From The First Affiliated Hospital of Soochow University Hospital, a complete of 52 paired GC and the nearby normal tissues were taken. All patients had not received any chemotherapy, radiotherapy, or any adjuvant therapies before surgical section. For future use, all the tissue samples were instantly preserved in the liquid nitrogen. The Ethical Committee of the First Affiliated Hospital of Soochow University approved this study, and all subjects provided written informed permission. According to the average miR-223 expression in GC patients, all participants were divided into miR-223 high and miR-223 low groups. Table1 has comprehensive clinicopathological data.Table 1
Clinicopathologic variables and miR-223 expression in 52 GC patients.
VariableMiR-223 expressionHigh (n = 26)Low (n = 26)p valueAge<651590.275≥651117GenderMale20180.412Female68Tumor locationProximal stomach470.583Distal stomach1413Whole stomach86Tumor size (cm)<57120.398≥51914Histology gradeLow1180.217Medium1315High23Regional lymph node metastasisNegative11111.00Positive1515TNM stageI/II6140.022∗III/IV2012Live metastasisNegative19260.004∗Positive70Borrmann typeI230.026∗II137III615IV51


### 2.2. Cell Lines, Culture, and Transfection

Five GC cell lines (AGS, BGC823, MKN45, MGC803, and SGC7901) and human gastric mucosa fibroblasts GES-1 were provided by the American Type Culture Collection (ATCC, Manassas, VA, USA). Inside a 5% CO2 saturated incubator at 37°C, cell lines were cultured in media (DMEM or RPMI-1640) that contains fetal bovine serum (FBS, 10% v/v) and streptomycin (1% v/v). The miR-223 inhibitor or the inhibitor NC were transfected when the confluence of MGC803 cells reached 70%–90% utilizing 2000 Lipofectamine (Invitrogen) in accordance with the manufacturer’s instructions. The inhibitor negative control (inhibitor NC) and human miR-223 inhibitor were given by GenePharma Co.Ltd (Shanghai). The inhibitor NC sequences for miR-223 are as follows: miR-223 inhibitor 5′-GGGGUAUUUGACAAACUGACA-3′; miR-223 NC 5′-CAUUUACCAUAUUCGGAGCUUCAGUAC-3′.


### 2.3. Total RNA Isolation and Quantitative Reverse Transcription PCR

The total RNA was extracted using RiboEX (Invitrogen). Afterward, using a miRNA reverse transcription kit, the RNA had been reversed transcribed to cDNA. The miR-223 expression was determined utilizing a Hairpin-itTM miRNAs qPCR kit (GenePharma) and an ABI PRISM 7000 tool (Applied Biosystems, Waltham, MA, USA). As endogenous controls, U6 and GAPDH were employed. Predenaturation was carried out at 95°C for 30 s followed by 40 cycles for 5 s at 95°C for 5 s and 60°C for 30 s. 2−ΔΔct was used to calculate the relative expression. The primers used in this research are listed as follows: GAPDH forward, 5′-CATACCAGGAAATGAGCTTG-3′, and reverse, 5′-ATGACATCAAGAAGGTGGTG-3′; U6 forward, 5′-CAAATCGGAGCATCGTGAATGCC-3′, and reverse, 5′-CAATACCATGCCGCCCAGGTC-3′; miR-223 forward, 5′-GGCAGCACCCCATAAACTGTT-3′, and reverse 5′-CAGTGCGTGTCGTGTCGTGGAG-3′; and RhoB forward, 5′-CGAATCCATTCAAATCCGGGATCCG-3′, and reverse 5′-AAGGCATTCAATCGGACTTACv3′.


### 2.4. Cell Apoptosis

After 48 h of transfection, the MGC803 cells have been harvested, as well as the supernatant was wasted via centrifugation. After that, cell washing was performed three times and apoptosis was identified using the Annexin V-PE and 7-AAD cell apoptosis detection kit (BD, Franklin Lakes, NJ, USA) as directed by the producer. To summarize, 10μl Annexin V-PE and 7-AAD were used for dyeing cells, respectively. Moreover, for assessing the fluorescence of PE and 7-AAD, flow cytometry was performed using a 515 nm and 620 nm band-pass filter set to 488 nm, respectively. Apoptotic cells were identified as Annexin-V+/7-AAD and V+/7-AAD+ cells.


### 2.5. Scratch Assay

For the scratch assay, cells have been cultured to 80% convergence in 12-well plates and wounded with a 200μl pipette tip. Under an inverted microscope, cell migration was photographed at 0 and 24 h (Zees, Germany). The NIH ImageJ program was used to assess cell movement.


### 2.6. Transwell Assay

The 8μm pore upper chamber (BD Biosciences, NJ, USA) was covered with Matrigel (200 g/ml, Corning, Shanghai, China) and heated to 37°C for the transwell assay. After two washes with serum-free media, in each cell density of 1 × 105 cells/mL, cells have been placed in the serum-free medium. The apical chamber was packed with 500 μl serum-free media that contain cells (5 × 104), and the basolateral chamber was packed with 750 μl media that hold 20% FBS. Both chambers were grown at 37°C for 48 hours. The Transwell chamber was removed, and the cells next to the superior lateral membranes were wiped clean and were stained with a 0.5% crystal violet. They were then photographed under an optical microscope.


### 2.7. Western Blot

The total proteins isolated from cells were measured using BCA kits and lysis buffer (RIPA, Cell Signaling) (Beyotime, China). All the protein samples (30μg) were split up using an SDS polyacrylamide gel and then conveyed to polyvinylidene difluoride (PVDF) membranes (Invitrogen). After blocking at room temperature with 5% skim milk for 1 h in PBS and then at 4°C overnight, the PVDF membranes were protected with primary antibodies anti-RhoB (ab155149; 1 : 1000; Abcam) and anti-GAPDH (ab9485; 1 : 1000; Abcam). Membranes were washed, and then, a goat anti-rabbit secondary antibody preincubated for an hour and labeled with horseradish peroxidase (ab96899; 1 : 1000; Abcam) was used and then rinsed with PBS. ECL detection reagent was used to visualize the protein bands (Pierce, Rockford, IL, United States). ImageJ software was used to quantify western blot densitometry bands.


### 2.8. Dual-Luciferase Reporter Quantitative Analysis

The target genes and binding sites were predicted using TargetScan for RhoB and miR-223. The mutant and wild-type binding sites on RhoB’s 3′UTR were subsequently replicated into that pmirGLO vector. The vectors PrimGLO-RhoB-wt and primGLO-RhoB-mut were subsequently cotransfected into cells with miR-223 mimics or miR-NC. Cells were cultured in 96-well plates for 48 h, and utilizing a dual-luciferase reporter gene assay system (Promega), luciferase activity was determined following to the manufacturer’s instructions.


### 2.9. Xenograft Tumor

Female BALB/c athymic nude mice aged 6–8 weeks were purchased from Vital River Co. Ltd. (Beijing, China). Subcutaneous injection of MGC803 cells established the xenograft tumor model. MGC803 cells (5 × 106) were intravenously injected into the armpits of every single mouse’s left forearm. The tumor volume and weight of tumors with various treatments were determined four weeks after injection. The volume of the tumor (mean ± sem; mm3) was determined using the following equation:(1)Vmm2=Smm×Lmm2,where S stands for the lowest and L represents the biggest perpendicular tumor diameters [14]. The Institutional Committee of The First Affiliated Hospital of Soochow University authorized all experiments with mice.


### 2.10. Statistical Analysis

SPSS 21.0 was utilized for analyzing data point for this study. The Mann–WhitneyU test was performed for determining correlations among miR-223 expressions with clinicopathological characteristics between two groups, and the Kruskal–Wallis test was employed to determine correlations among three or more groups. The Kaplan–Meier technique with a log-rank test was used to study the associations between miR-223 survival and expression. A Cox regression model was utilized to assess the univariate and multivariate statistical analysis of predictive variables. The ANOVA or Student’s t-test were used to evaluate the data. p<0.05 was seen statistically meaningful.


## 2.1. Tissue Samples

From The First Affiliated Hospital of Soochow University Hospital, a complete of 52 paired GC and the nearby normal tissues were taken. All patients had not received any chemotherapy, radiotherapy, or any adjuvant therapies before surgical section. For future use, all the tissue samples were instantly preserved in the liquid nitrogen. The Ethical Committee of the First Affiliated Hospital of Soochow University approved this study, and all subjects provided written informed permission. According to the average miR-223 expression in GC patients, all participants were divided into miR-223 high and miR-223 low groups. Table1 has comprehensive clinicopathological data.Table 1
Clinicopathologic variables and miR-223 expression in 52 GC patients.
VariableMiR-223 expressionHigh (n = 26)Low (n = 26)p valueAge<651590.275≥651117GenderMale20180.412Female68Tumor locationProximal stomach470.583Distal stomach1413Whole stomach86Tumor size (cm)<57120.398≥51914Histology gradeLow1180.217Medium1315High23Regional lymph node metastasisNegative11111.00Positive1515TNM stageI/II6140.022∗III/IV2012Live metastasisNegative19260.004∗Positive70Borrmann typeI230.026∗II137III615IV51


## 2.2. Cell Lines, Culture, and Transfection

Five GC cell lines (AGS, BGC823, MKN45, MGC803, and SGC7901) and human gastric mucosa fibroblasts GES-1 were provided by the American Type Culture Collection (ATCC, Manassas, VA, USA). Inside a 5% CO2 saturated incubator at 37°C, cell lines were cultured in media (DMEM or RPMI-1640) that contains fetal bovine serum (FBS, 10% v/v) and streptomycin (1% v/v). The miR-223 inhibitor or the inhibitor NC were transfected when the confluence of MGC803 cells reached 70%–90% utilizing 2000 Lipofectamine (Invitrogen) in accordance with the manufacturer’s instructions. The inhibitor negative control (inhibitor NC) and human miR-223 inhibitor were given by GenePharma Co.Ltd (Shanghai). The inhibitor NC sequences for miR-223 are as follows: miR-223 inhibitor 5′-GGGGUAUUUGACAAACUGACA-3′; miR-223 NC 5′-CAUUUACCAUAUUCGGAGCUUCAGUAC-3′.


## 2.3. Total RNA Isolation and Quantitative Reverse Transcription PCR

The total RNA was extracted using RiboEX (Invitrogen). Afterward, using a miRNA reverse transcription kit, the RNA had been reversed transcribed to cDNA. The miR-223 expression was determined utilizing a Hairpin-itTM miRNAs qPCR kit (GenePharma) and an ABI PRISM 7000 tool (Applied Biosystems, Waltham, MA, USA). As endogenous controls, U6 and GAPDH were employed. Predenaturation was carried out at 95°C for 30 s followed by 40 cycles for 5 s at 95°C for 5 s and 60°C for 30 s. 2−ΔΔct was used to calculate the relative expression. The primers used in this research are listed as follows: GAPDH forward, 5′-CATACCAGGAAATGAGCTTG-3′, and reverse, 5′-ATGACATCAAGAAGGTGGTG-3′; U6 forward, 5′-CAAATCGGAGCATCGTGAATGCC-3′, and reverse, 5′-CAATACCATGCCGCCCAGGTC-3′; miR-223 forward, 5′-GGCAGCACCCCATAAACTGTT-3′, and reverse 5′-CAGTGCGTGTCGTGTCGTGGAG-3′; and RhoB forward, 5′-CGAATCCATTCAAATCCGGGATCCG-3′, and reverse 5′-AAGGCATTCAATCGGACTTACv3′.


## 2.4. Cell Apoptosis

After 48 h of transfection, the MGC803 cells have been harvested, as well as the supernatant was wasted via centrifugation. After that, cell washing was performed three times and apoptosis was identified using the Annexin V-PE and 7-AAD cell apoptosis detection kit (BD, Franklin Lakes, NJ, USA) as directed by the producer. To summarize, 10μl Annexin V-PE and 7-AAD were used for dyeing cells, respectively. Moreover, for assessing the fluorescence of PE and 7-AAD, flow cytometry was performed using a 515 nm and 620 nm band-pass filter set to 488 nm, respectively. Apoptotic cells were identified as Annexin-V+/7-AAD and V+/7-AAD+ cells.


## 2.5. Scratch Assay

For the scratch assay, cells have been cultured to 80% convergence in 12-well plates and wounded with a 200μl pipette tip. Under an inverted microscope, cell migration was photographed at 0 and 24 h (Zees, Germany). The NIH ImageJ program was used to assess cell movement.


## 2.6. Transwell Assay

The 8μm pore upper chamber (BD Biosciences, NJ, USA) was covered with Matrigel (200 g/ml, Corning, Shanghai, China) and heated to 37°C for the transwell assay. After two washes with serum-free media, in each cell density of 1 × 105 cells/mL, cells have been placed in the serum-free medium. The apical chamber was packed with 500 μl serum-free media that contain cells (5 × 104), and the basolateral chamber was packed with 750 μl media that hold 20% FBS. Both chambers were grown at 37°C for 48 hours. The Transwell chamber was removed, and the cells next to the superior lateral membranes were wiped clean and were stained with a 0.5% crystal violet. They were then photographed under an optical microscope.


## 2.7. Western Blot

The total proteins isolated from cells were measured using BCA kits and lysis buffer (RIPA, Cell Signaling) (Beyotime, China). All the protein samples (30μg) were split up using an SDS polyacrylamide gel and then conveyed to polyvinylidene difluoride (PVDF) membranes (Invitrogen). After blocking at room temperature with 5% skim milk for 1 h in PBS and then at 4°C overnight, the PVDF membranes were protected with primary antibodies anti-RhoB (ab155149; 1 : 1000; Abcam) and anti-GAPDH (ab9485; 1 : 1000; Abcam). Membranes were washed, and then, a goat anti-rabbit secondary antibody preincubated for an hour and labeled with horseradish peroxidase (ab96899; 1 : 1000; Abcam) was used and then rinsed with PBS. ECL detection reagent was used to visualize the protein bands (Pierce, Rockford, IL, United States). ImageJ software was used to quantify western blot densitometry bands.


## 2.8. Dual-Luciferase Reporter Quantitative Analysis

The target genes and binding sites were predicted using TargetScan for RhoB and miR-223. The mutant and wild-type binding sites on RhoB’s 3′UTR were subsequently replicated into that pmirGLO vector. The vectors PrimGLO-RhoB-wt and primGLO-RhoB-mut were subsequently cotransfected into cells with miR-223 mimics or miR-NC. Cells were cultured in 96-well plates for 48 h, and utilizing a dual-luciferase reporter gene assay system (Promega), luciferase activity was determined following to the manufacturer’s instructions.


## 2.9. Xenograft Tumor

Female BALB/c athymic nude mice aged 6–8 weeks were purchased from Vital River Co. Ltd. (Beijing, China). Subcutaneous injection of MGC803 cells established the xenograft tumor model. MGC803 cells (5 × 106) were intravenously injected into the armpits of every single mouse’s left forearm. The tumor volume and weight of tumors with various treatments were determined four weeks after injection. The volume of the tumor (mean ± sem; mm3) was determined using the following equation:(1)Vmm2=Smm×Lmm2,where S stands for the lowest and L represents the biggest perpendicular tumor diameters [14]. The Institutional Committee of The First Affiliated Hospital of Soochow University authorized all experiments with mice.


## 2.10. Statistical Analysis

SPSS 21.0 was utilized for analyzing data point for this study. The Mann–WhitneyU test was performed for determining correlations among miR-223 expressions with clinicopathological characteristics between two groups, and the Kruskal–Wallis test was employed to determine correlations among three or more groups. The Kaplan–Meier technique with a log-rank test was used to study the associations between miR-223 survival and expression. A Cox regression model was utilized to assess the univariate and multivariate statistical analysis of predictive variables. The ANOVA or Student’s t-test were used to evaluate the data. p<0.05 was seen statistically meaningful.


## 3. Results

### 3.1. MiR-223 Overexpressed in GC Cells and Tissues

It has been established that miR-223 has a pivotal role in the progression of cancer. To ascertain the function of miR-223 in GC, the miR-223 expression was compared between GC tissues and their surrounding normal tissues. Figure1(a) shows the expression of miR-223 has been dramatically enhanced in human GC tissue as compared to nearby normal tissues. Additionally, we revealed that the expression of miR-223 was markedly increased in GC cell lines, including MGC803, BGC823, SGC7901, AGS, and MKN45 (Figure 1(b)) as compared with human gastric epithelial cell line.Figure 1
MiR-223 expression was increased in GC tissue and associated with poor prognosis of GC patients. (a) MiR-223 expression was increased in GC tissues (n = 52) compared to adjacent normal tissues (n = 52) detected by qRT-PCR. (b) The expression levels of miR-223 were detected by qRT-PCR in different GC cell lines, including MGC803, BGC823, SGC7901, AGS, and MKN45. GAPDH acts as an internal control. (c) The expression of miR-223 in GC tissues was negatively correlated with the prognosis of GC patients; ∗∗∗p<0.001.
(a)(b)(c)


### 3.2. MiR-223 Overexpression Was Related to the Progression and the Adverse Prognosis of GC

To further validate the correlation between the expression of miR-223 and advancement of GC, we examined the relations between the clinicopathological features and miR-223 expression of patients with GC. The results demonstrated a positive and meaningful correlation between high miR-223 expression and TNM stage (p=0.022), live metastasis (p=0.004), and Borrmann type (p=0.026) (Table 1). To investigate the involvement of miR-223 expression and the prognosis in GC patients, we randomly selected 26 cases with elevated miR-223 expression (>median value) and 26 instances with low miR-223 expression (median value). As shown in Figure 1(c), the log-rank test and Kaplan–Meier curves reported that the total survival rate of GC patients with the low expression of miR-223 was substantially greater than that of GC patients with high expression of miR-223. Additionally, miR-223 expression was considered an autonomous predictor of overall survival on both univariate and multivariate studies (Tables 2 and 3).Table 2
Univariate analyses of prognostic variables of overall survival in GC patients.
VariableRR95% CIp valueAge0.9160.467–1.7970.961Gender0.9530.481–1.8880.890Tumor location1.2420.707–2.1820.451Tumor size1.9320.872–4.2790.105TNM stage0.1880.077–0.4570.001∗Live metastasis6.9112.903–16.460.001∗Regional lymph node metastasis2.0640.998–4.2660.044∗Histology grade0.5500.309–0.9790.042∗Borrmann type1.6561.048–2.6160.031∗MiR-223 expression2.8681.427–5.7660.003∗Table 3
Multivariate analyses of prognostic variables of overall survival in GC patients.
VariableRR95% CIp valueTNM stage0.3130.111–0.8870.029∗Live metastasis4.6661.462–14.890.009∗Regional lymph node metastasis3.1821.234–8.2050.017∗Histology grade0.7940.417–1.5120.483Borrmann type1.0520.611–1.8130.854MiR-223 expression2.4991.125–5.5490.024∗


### 3.3. Downregulation of MiR-223 Inhibited Cell Migration and Invasion and Promoted Cell Apoptosis of GC Cells

In order to verify the function of miR-223 in GC development, we inhibited miR-233 expression in MGC803 cells using a miR-223 inhibitor. As demonstrated in Figure2(a), the expression of miR-223 was dramatically downregulated in MGC803 cells following miR-223 inhibitor transfection compared to the NC-inhibitor group. The scratch assay revealed a significant reduction in the capacity of MGC803 cells to migrate following transfection with miR-223 inhibitors in comparison with the control cells as shown in Figure 2(b). Transwell assays revealed that silencing miR-223 significantly reduced MGC803 cells’ invasive potential (Figure 2(c)). Additionally, flow cytometry analysis revealed that silencing miR-223 dramatically increased cell death in MGC803 cells compared to the control group (Figure 2(d)). The following evidence revealed that silencing miR-223 decreased GC cell invasion and migration while promoting cell death.Figure 2
Downregulation of miR-223 inhibited cell migration and invasion and promoted cell apoptosis of GC cells. (a) qRT-PCR was used to detect the miR-223 expression in MGC803 cells after transfection with miR-223 inhibitor. (b) Scratch assay was used to analyze the migration abilities of MGC803 cells after transfection with miR-223 inhibitor. (c) Transwell assay was used to analyze the invasive abilities of MGC803 cells after transfection with miR-223 inhibitor. (d) Cell apoptosis of MGC803 after transfection with miR-223 inhibitor was detected by flow cytometry;∗∗∗p<0.001.
(a)(b)(c)(d)


### 3.4. RhoB Is a Direct Target of MiR-223

To determine miR-223’s downstream targets, TargetScan was used. Results suggest that the miR-223 had a binding site on the 3′UTR of RhoB (Figure3(a)). The dual-luciferase report assay showed that when miR-223 mimics and pmirGLO vectors containing wild-type binding sites were cotransfected, the relative luciferase was significantly reduced, whereas when miR-223 mimics and pmirGLO vectors containing mutant binding sites were cotransfected, the relative luciferase was unaffected (Figure 3(b)). Additionally, western blot and qRT-PCR analysis showed that the treatment with miR-223 inhibitor dramatically increased RhoB expression relative to the NC group, mutually at the mRNA and protein levels (Figures 3(c) and 3(d)). These results established that RhoB is a miR-223 direct target.Figure 3
RhoB was a direct target of miR-223. (a) TargetScan was used to predict the target and the binding site between miR-223 and the RhoB 3′UTR. (b) The dual-luciferase reporter system was used to detect the regulatory of miR-223 to RhoB. (c, d) qRT-PCR and western blot were used to detect the mRNA and the protein level of RhoB in MGC803 cells after transfection with a miR-223 inhibitor;∗∗p<0.01 and ∗∗∗p<0.001.
(a)(b)(c)(d)


### 3.5. Downregulation of MiR-223 Inhibited Tumor Growth In Vivo

The importance of miR-223 in the evolution of GC tumors was also investigated in vivo using a xenograft model. As illustrated in Figures4(a) and 4(b), when nude mice were treated with miR-233 inhibitors, the tumor volume was dramatically reduced in comparison to the control group. Additional study revealed that, after treatment with miR-223 inhibitors, when linked to the control group, tumor size and weight were substantially reduced (Figures 4(c) and 4(d)).Figure 4
Downregulation of miR-223 inhibited tumor growth in vivo. (a, b) The representative pictures of tumor growth affected by the miR-223 inhibitor. (c, d) The tumor size and tumor weight in nude mice affected by the miR-223 inhibitor;p∗<0.05.
(a)(b)(c)(d)


## 3.1. MiR-223 Overexpressed in GC Cells and Tissues

It has been established that miR-223 has a pivotal role in the progression of cancer. To ascertain the function of miR-223 in GC, the miR-223 expression was compared between GC tissues and their surrounding normal tissues. Figure1(a) shows the expression of miR-223 has been dramatically enhanced in human GC tissue as compared to nearby normal tissues. Additionally, we revealed that the expression of miR-223 was markedly increased in GC cell lines, including MGC803, BGC823, SGC7901, AGS, and MKN45 (Figure 1(b)) as compared with human gastric epithelial cell line.Figure 1
MiR-223 expression was increased in GC tissue and associated with poor prognosis of GC patients. (a) MiR-223 expression was increased in GC tissues (n = 52) compared to adjacent normal tissues (n = 52) detected by qRT-PCR. (b) The expression levels of miR-223 were detected by qRT-PCR in different GC cell lines, including MGC803, BGC823, SGC7901, AGS, and MKN45. GAPDH acts as an internal control. (c) The expression of miR-223 in GC tissues was negatively correlated with the prognosis of GC patients; ∗∗∗p<0.001.
(a)(b)(c)


## 3.2. MiR-223 Overexpression Was Related to the Progression and the Adverse Prognosis of GC

To further validate the correlation between the expression of miR-223 and advancement of GC, we examined the relations between the clinicopathological features and miR-223 expression of patients with GC. The results demonstrated a positive and meaningful correlation between high miR-223 expression and TNM stage (p=0.022), live metastasis (p=0.004), and Borrmann type (p=0.026) (Table 1). To investigate the involvement of miR-223 expression and the prognosis in GC patients, we randomly selected 26 cases with elevated miR-223 expression (>median value) and 26 instances with low miR-223 expression (median value). As shown in Figure 1(c), the log-rank test and Kaplan–Meier curves reported that the total survival rate of GC patients with the low expression of miR-223 was substantially greater than that of GC patients with high expression of miR-223. Additionally, miR-223 expression was considered an autonomous predictor of overall survival on both univariate and multivariate studies (Tables 2 and 3).Table 2
Univariate analyses of prognostic variables of overall survival in GC patients.
VariableRR95% CIp valueAge0.9160.467–1.7970.961Gender0.9530.481–1.8880.890Tumor location1.2420.707–2.1820.451Tumor size1.9320.872–4.2790.105TNM stage0.1880.077–0.4570.001∗Live metastasis6.9112.903–16.460.001∗Regional lymph node metastasis2.0640.998–4.2660.044∗Histology grade0.5500.309–0.9790.042∗Borrmann type1.6561.048–2.6160.031∗MiR-223 expression2.8681.427–5.7660.003∗Table 3
Multivariate analyses of prognostic variables of overall survival in GC patients.
VariableRR95% CIp valueTNM stage0.3130.111–0.8870.029∗Live metastasis4.6661.462–14.890.009∗Regional lymph node metastasis3.1821.234–8.2050.017∗Histology grade0.7940.417–1.5120.483Borrmann type1.0520.611–1.8130.854MiR-223 expression2.4991.125–5.5490.024∗


## 3.3. Downregulation of MiR-223 Inhibited Cell Migration and Invasion and Promoted Cell Apoptosis of GC Cells

In order to verify the function of miR-223 in GC development, we inhibited miR-233 expression in MGC803 cells using a miR-223 inhibitor. As demonstrated in Figure2(a), the expression of miR-223 was dramatically downregulated in MGC803 cells following miR-223 inhibitor transfection compared to the NC-inhibitor group. The scratch assay revealed a significant reduction in the capacity of MGC803 cells to migrate following transfection with miR-223 inhibitors in comparison with the control cells as shown in Figure 2(b). Transwell assays revealed that silencing miR-223 significantly reduced MGC803 cells’ invasive potential (Figure 2(c)). Additionally, flow cytometry analysis revealed that silencing miR-223 dramatically increased cell death in MGC803 cells compared to the control group (Figure 2(d)). The following evidence revealed that silencing miR-223 decreased GC cell invasion and migration while promoting cell death.Figure 2
Downregulation of miR-223 inhibited cell migration and invasion and promoted cell apoptosis of GC cells. (a) qRT-PCR was used to detect the miR-223 expression in MGC803 cells after transfection with miR-223 inhibitor. (b) Scratch assay was used to analyze the migration abilities of MGC803 cells after transfection with miR-223 inhibitor. (c) Transwell assay was used to analyze the invasive abilities of MGC803 cells after transfection with miR-223 inhibitor. (d) Cell apoptosis of MGC803 after transfection with miR-223 inhibitor was detected by flow cytometry;∗∗∗p<0.001.
(a)(b)(c)(d)


## 3.4. RhoB Is a Direct Target of MiR-223

To determine miR-223’s downstream targets, TargetScan was used. Results suggest that the miR-223 had a binding site on the 3′UTR of RhoB (Figure3(a)). The dual-luciferase report assay showed that when miR-223 mimics and pmirGLO vectors containing wild-type binding sites were cotransfected, the relative luciferase was significantly reduced, whereas when miR-223 mimics and pmirGLO vectors containing mutant binding sites were cotransfected, the relative luciferase was unaffected (Figure 3(b)). Additionally, western blot and qRT-PCR analysis showed that the treatment with miR-223 inhibitor dramatically increased RhoB expression relative to the NC group, mutually at the mRNA and protein levels (Figures 3(c) and 3(d)). These results established that RhoB is a miR-223 direct target.Figure 3
RhoB was a direct target of miR-223. (a) TargetScan was used to predict the target and the binding site between miR-223 and the RhoB 3′UTR. (b) The dual-luciferase reporter system was used to detect the regulatory of miR-223 to RhoB. (c, d) qRT-PCR and western blot were used to detect the mRNA and the protein level of RhoB in MGC803 cells after transfection with a miR-223 inhibitor;∗∗p<0.01 and ∗∗∗p<0.001.
(a)(b)(c)(d)


## 3.5. Downregulation of MiR-223 Inhibited Tumor Growth In Vivo

The importance of miR-223 in the evolution of GC tumors was also investigated in vivo using a xenograft model. As illustrated in Figures4(a) and 4(b), when nude mice were treated with miR-233 inhibitors, the tumor volume was dramatically reduced in comparison to the control group. Additional study revealed that, after treatment with miR-223 inhibitors, when linked to the control group, tumor size and weight were substantially reduced (Figures 4(c) and 4(d)).Figure 4
Downregulation of miR-223 inhibited tumor growth in vivo. (a, b) The representative pictures of tumor growth affected by the miR-223 inhibitor. (c, d) The tumor size and tumor weight in nude mice affected by the miR-223 inhibitor;p∗<0.05.
(a)(b)(c)(d)


## 4. Discussion

MiRNA expression levels were found to be related with the prognosis of human cancers and may serve as biomarkers of tumor prognosis [15–17]. Li et al. discovered that stool miR-135b-5p had excellent diagnosis performance in advanced colorectal cancer [18]. miR-183-5p expression was decreased in GC tissues, suggesting that it may operate as a predictive biomarker [19]. Li and Zou also demonstrated that miR-652 expression levels were considerably increased in GC tissues and acted as a predictive biomarker in GC [20]. Additionally, miR-223 has been shown to be a predictive biomarker for malignancies. Bhattacharya et al. discovered miR-30e and miR-223 as potential biomarkers for hepatocellular carcinoma, regardless of the pathogenesis, and additional analyses are needed for their diagnostic utility [21]. In individuals with colorectal cancer, miR-223 overexpression was linked to tumor spreading and a poor prognosis [22].We discovered that miR-223 had been overexpressed in GC tissues in comparison to nearby normal tissues in the current investigation. Furthermore, elevated expression of miR-223 was linked with TNM stage (p=0.022), live metastasis (p=0.004), Borrmann type, and a poor overall survival rate in GC patients. Notably, miR-223 expression was considered as an independent predictor of overall survival in both univariate and multivariate studies. The overall findings suggested that miR-223 might be employed as a gastric cancer biomarker.MiR-223 has been implicated in a wide range of biological mechanisms associated with GC, which include proliferation, invasion, metastasis, and treatment resistance. The proliferation and invasion of the GC cells had been increased by miR-223 via modulating the expression of Arid1a23 [23]. Moreover, another analysis performed by Liu et al. suggested that miR-223 can also target the long noncoding RNA TP73 antisense RNA1 in order to increase invasion of GC [24]. Through targeting FBXW7, miR-223 influenced the trastuzumab sensitivity of a HER2-positive GC cell line [25]. Additionally, in GC cells, miRNA-223 also facilitated invasion and metastasis through influencing EPB41L3 (tumor suppressor) [26]. According to the findings of the current investigation, suppressing miR-223 substantially lowered cell movement as well as penetration of MGC803 cells and increased cell death. Additionally, we discovered that silencing miR-223 decreased in vivo tumor progression. It was determined by these observations that miR-223 played a decisive role in reversing GC development.RhoB has shown the ability to function both as a cancer-causing gene and as a tumor suppressor during the entire cancer growth and development [27, 28]. Ho et al. discovered that gallic acid suppressed cell metastasis and invasive growth in GC through increasing RhoB expression [29]. NSC12618, a highly active anticancer compound, enhanced RhoB expression via c-Jun N-terminal kinase signaling and caused death in gastric carcinoma NUGC-3 cells [30]. Li et al. suggested that by targeting the miR-197/RhoB signaling pathway, the circRNA Hsa_circ_0001017 suppressed GC cell proliferation, movement, and infiltration [31]. KR28 (1-allyl-4-dodecanoyl-1-ethyl-piperazin-1-ium; bromide), a new anticancer drug, promoted apoptosis by upregulating c-Abl and activating p38 MAPK/ATF-2 in response to ROS-mediated RhoB production [32]. Our study revealed that the RhoB 3′UTR has a miR-223 binding site. Furthermore, we discovered that silencing miR-223 significantly boosted RhoB protein levels in MGC803 cells, implying that miR-223 may regulate GC development via RhoB.In conclusion, the current research data showed that the expression of miR-223 was enhanced in GC tissues and that the miR-223 downregulation reduced GC progression via targeting RhoB. Considering this study result recommended an increase in the miR-223 expression could be valuable prognostic biomarker for GC.



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*Source: 6708871-2022-01-06.xml*