Targeted therapies in gastric cancer treatment: where we are and where we are going

Advances in targeted therapy for human epidermal growth factor receptor 2 positive in advanced gastric cancer

Emerging therapeutic methods represented by targeted therapy are effective supplements to traditional first-line chemoradiotherapy resistance. Human epidermal growth factor receptor 2 (HER2) is one of the most important targets in targeted therapy for gastric cancer. Trastuzumab combined with chemotherapy has been used as the first-line treatment for advanced gastric cancer. The safety and efficacy of pertuzumab and margetuximab in the treatment of gastric cancer have been verified. However, monoclonal antibodies, due to their large molecular weight, inability to penetrate the blood-brain barrier, and drug resistance, lead to decreased therapeutic efficacy, so it is necessary to explore the efficacy of other HER2-targeting therapies in gastric cancer. Small-molecule tyrosine kinase inhibitors, such as lapatinib and pyrrotinib, have the advantages of small molecular weight, penetrating the blood-brain barrier and high oral bioavailability, and are expected to become the drugs of choice for perioperative treatment and neoadjuvant therapy of gastric cancer after validation by large-scale clinical trials in the future. Antibo-drug conjugate, such as T-DM1 and T-DXd, can overcome the resistance of monoclonal antibodies despite their different mechanisms of tumor killing, and are a supplement for the treatment of patients who have failed the treatment of monoclonal antibodies such as trastuzumab. Therefore, after more detailed stratification of gastric cancer patients, various gastric cancer drugs targeting HER2 are expected to play a more significant role.

High Expression of UPK3A Promotes the Progression of Gastric Cancer Cells by Inactivating p53 Pathway

Background

Gastric cancer is a common gastrointestinal tract cancer and is a considerable health burden worldwide. TCGA analysis found Uroplakin 3A (UPK3A) was upregulated in gastric cancer tissues. Our study was designed to investigate the underlying mechanism of Uroplakin 3A (UPK3A) in gastric cancer.

Methods

Data from TCGA database were used to assess the expression, and Kaplan-Meier plotter analysis was used to assess the prognosis value of UPK3A. Furthermore, there are effects of UPK3A silencing on the activity, proliferation, migration, and invasion of human gastric cancer cells (SNU-216 and HGC-27) using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), colony formation, wound healing, and Transwell assays. In addition, the expression of UPK3A, p53, KLF4, ZMAT3, MDM2, and SP1 was detected by qRT-PCR and Western blot assay.

Results

UPK3A was markedly upregulated in gastric cancer tissues compared to that in normal tissues, and patients with high UPK3A level showed poor prognosis. UPK3A was highly expressed in human gastric cancer cell lines compared to that in a normal human gastric epithelial cell line. Silencing of UPK3A inhibited the proliferation, migration, and invasion of gastric cancer cells. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis revealed that UPK3A was involved in the p53 signaling pathway. UPK3A suppressed the activation of p53 signaling pathway, and treatment with Pifithrin-α (an inhibitor of the p53 signaling pathway) or silencing of p53 significantly reversed the effect of UPK3A silencing on the expression of p53, KLF4, ZMAT3, MDM2, and SP1.

Conclusion

Our findings showed that UPK3A promotes the progression of gastric cancer by regulating the p53 signaling pathway and could be a potential therapeutic target for gastric cancer.

The Expression, Prognostic Value, and Immunological Correlation of MCEMP1 and its Potential Role in Gastric Cancer

Purpose

Gastric cancer (GC) is a lethal cancer with a poor 5-year relative survival, which requires a new research perspective. Our study aims to explore the biological impact of the mast cell-expressed membrane protein 1 (MCEMP1) in GC, which includes its expression and potential biological functions.

Methods

The expression of MCEMP1 was assessed through public databases. The GO, KEGG, and GESA analyses were conducted to explore the biofunction of MCEMP1. And ssGSEA was used to analyze the infiltration of the immune cells for MCEMP1. The proliferation, migration, and invasion of GC cells were analyzed through CCK8, colony-forming, wound healing, Transwell, and Western blot assay.

Results

The expression of MCEMP1 was higher in GC tissues. Further, we found a close relationship between MCEMP1 and poorer prognosis of gastric cancer by prognostic analysis. The functional analysis showed that MCEMP1 is involved in immune, inflammation, and metabolism-related pathways. The ssGSEA analysis indicated MCEMP1 mRNA expression was associated with immune infiltration of multiple immune cells. In cellular experiments, the invasion and metastasis of gastric cancer cells could be promoted by regulating the rise of MCEMP1 expression. Western blot analysis showed that regulation of MCEMP1 expression can affect EMT-related protein expression and that NF-κB expression is involved in this process.

Conclusion

MCEMP1 shows a potential value for the prognosis in GC. And, abnormal expression of MCEMP1 in GC is correlated with tumor immune cell infiltration. In in vitro experiments, MCEMP1 can affect the proliferation, migration, and invasion of GC cells by regulating EMT, in which TLR4/NOD2/NF-κB was involved.

Circ_PGPEP1 Serves as a Sponge of miR-1297 to Promote Gastric Cancer Progression via Regulating E2F3

BACKGROUND

Circular RNA (circRNA) is a special kind of noncoding RNA that plays a vital function in the progression of gastric cancer (GC). However, the role of a new circRNA, circ_PGPEP1, in GC is unclear.

AIMS

Exploring the role and mechanism of circ_PGPEP1 in GC progression.

METHODS

The expression levels of circ_PGPEP1, miR-1297, and E2F transcription factor 3 (E2F3) were determined using quantitative real-time PCR. Flow cytometry, colony formation assay, MTT assay, and transwell assay were used to evaluate cell cycle, apoptosis, proliferation, migration, and invasion. The protein levels of apoptosis-related markers and E2F3 were measured by western blot analysis. The interaction between circ_PGPEP1 and miR-1297 or miR-1297 and E2F3 was confirmed by dual-luciferase reporter assay. In addition, animal experiments were performed to assess the effect of circ_PGPEP1 on GC tumor growth in vivo.

RESULTS

Circ_PGPEP1 was a highly expressed circRNA in GC. Loss-of-function experiment indicated that circ_PGPEP1 silencing could induce cell cycle arrest and apoptosis, while inhibit proliferation, migration, and invasion in GC cells. MiR-1297 could be sponged by circ_PGPEP1, and its expression was downregulated in GC. MiR-1297 inhibitor could reverse the negatively regulation of circ_PGPEP1 knockdown on GC progression. Furthermore, we also found that E2F3 could be targeted by miR-1297, and its expression was positively regulated by circ_PGPEP1. Overexpression of E2F3 could invert the inhibitory effect of miR-1297 on GC progression. Animal experiments suggested that silenced circ_PGPEP1 could reduce GC tumor growth.

CONCLUSION

Our research showed that circ_PGPEP1 might serve as a potential biomarker for GC.

Cellular uptake and apoptotic properties of gemini curcumin in gastric cancer cells

INTRODUCTION

Curcumin is a polyphenolic natural compound, which has demonstrated to possess antioxidant, anti-inflammatory, and anticancer effects in vitro & in vivo. However, its applicability in cancer therapy has been limited due to its poor cellular uptake. Here, we aimed to evaluate the anticancer effect of novel gemini curcumin (Gemini-Cur) on the gastric cancer AGS cells.

METHOD

The AGS cancerous and HFF-2 non-cancerous cells were treated with Gemini-Cur and curcumin (Cur) in a time- and dose-dependent manner. Cellular toxicity was studied using MTT, fluorescence microscopy, annexin V/FITC, and cell cycle assays. Additionally, real-time PCR and western blotting were employed to evaluate the expression of Bax, Bcl-2 and survivin genes.

RESULTS

Our data indicated that Gemini-Cur is significantly taken into AGS cells compared to Cur. Moreover, the viability of Gemini-Cur treated cells was significantly reduced in a time- and dose-dependent manner (p < 0.001). Gemini-Cur compound induced G2/M cell cycle arrest that was followed by apoptosis in a time-dependent manner (p < 0.0001).

DISCUSSION

Taken together, our findings support the idea that Gemini-Cur has the potential to be considered as an anticancer agent.

Tryptophanol-Derived Oxazolopyrrolidone Lactams as Potential Anticancer Agents against Gastric Adenocarcinoma

Gastric cancer is one of the deadliest cancers in modern societies, so there is a high level of interest in discovering new drugs for this malignancy. Previously, we demonstrated the ability of tryptophanol-derived polycyclic compounds to activate the tumor suppressor protein p53, a relevant therapeutic target in cancer. In this work, we developed a novel series of enantiomerically pure tryptophanol-derived small molecules to target human gastric adenocarcinoma (AGS) cells. From an initial screening of fourteen compounds in AGS cell line, a hit compound was selected for optimization, leading to two derivatives selective for AGS gastric cells over other types of cancer cells (MDA-MB-231, A-549, DU-145, and MG-63). More importantly, the compounds were non-toxic in normal cells (HEK 293T). Additionally, we show that the growth inhibition of AGS cells induced by these compounds is mediated by apoptosis. Stability studies in human plasma and human liver microsomes indicate that the compounds are stable, and that the major metabolic transformations of these molecules are mono- and di-hydroxylation of the indole ring.

Identification of UAP1L1 as tumor promotor in gastric cancer through regulation of CDK6

Gastric cancer (GC) is one of the most commonly diagnosed malignancies in digestive tract and its underlying molecular mechanism is still not clear, so we aimed to reveal the relationship between GC and UDP-GlcNAc pyrophosphorylase-1 like 1 (UAP1L1). The detection of UAP1L1 expression in GC tumor and normal tissues was accomplished by immunohistochemistry and demonstrated the upregulation of UAP1L1 in GC, which was statistically associated with tumor grade. GC cell models constructed via transfection of UAP1L1-silencing/overexpressing lentiviruses were employed for evaluating the effects of UAP1L1 knockdown/overexpression on GC in vitro and in vivo. The results indicated that UAP1L1 played important role in development of GC through regulating cell proliferation, colony formation, cell apoptosis and cell migration. Subsequently, CDK6 was identified as a potential target in UAP1L1 induced regulation of GC, downregulation of which exhibited similar inhibition effects on GC with UAP1L1. Moreover, it was demonstrated that the promotion of GC by UAP1L1 overexpression could be significantly attenuated or even reversed by simultaneously silencing CDK6. In conclusion, UAP1L1 was reported to be a tumor promotor in the development and progression of GC which may exert its role through regulating CDK6 and may act as a candidate of therapeutic target in treatment.

Pain Relieving Effect of Intraoperative Chemical Splanchnicectomy of Celiac Ganglions in Patients with Resectable Pancreatic or Gastric Masses: A Randomized Clinical Trial

Background

Trials of intraoperative chemical splanchnicectomy during resection of pancreatic and gastric masses resulted in significant difference in a patient's postoperative pain. This study aims to determine if splanchnicectomy by alcohol neurolysis can relieve postoperative pain after gastrectomy and Whipple surgery. The study explores differences in outcomes at first four months after surgery.

Methods

Fifty-eight patients with gastric and 60 patients with pancreatic resectable masses were included (28 were lost to follow-up). Each randomized in control and intervention subgroups. Intervention subgroups underwent chemical blockage of celiac ganglions by ethanol injection at both sides of suprapancreatic aorta. Participants were asked to report their pain intensity according to the Visual Analogue Scale (VAS) at specific times.

Result

The overall postoperative pain of injected Whipple and gastrectomy subgroups was lower than the noninjected Whipple and gastrectomy subgroups (p < 0.001). The pain-modifying effect of the injection was not different between Whipple and gastrectomy groups (p=0.125).

Conclusion

Splanchnicectomy is recommended for pain reduction after abdominal operations. Perspective. This article presents positive effect of intraoperative chemical splanchnicectomy during resection of pancreatic and gastric masses on postoperative pain. This is an easy, effective, safe, and inexpensive procedure recommended for all operable gastric or pancreatic masses to palliate the pain degree.

Does the use of targeted agents in advanced gastroesophageal cancer increase complete response? A meta-analysis of 18 randomized controlled trials

Purpose

We aimed to investigate whether the use of targeted agents (TAs) in advanced gastroesophageal cancer (GEC) increased the complete response (CR) and to assess the surrogate endpoints for survival in the targeted treatment of GEC by using a meta-analysis of randomized controlled trials (RCTs).

Methods

Eligible studies were identified using Medline, PubMed, and meeting abstracts. Searches were last updated on April 30, 2018. We calculated the incidence and Peto odds ratio (Peto OR) of CR events in patients assigned to TAs compared with controls. Simple linear regression models were fitted for median overall survival (OS) and each surrogate [median progression-free survival (PFS), CRs, objective response rate (ORR), and disease control rate (DCR), respectively].

Results

A total of 7,892 GEC patients from 18 RCTs were included for analysis. The incidence of CR in GEC patients treated with TAs was 2.0% (95% CI, 1.3%–3.0%) compared with 1.7% (95% CI, 1.0%–2.7%) in the control arms. The use of TAs in advanced GEC had a tendency to improve the possibility of archiving CR (Peto OR 1.42; 95% CI, 0.98–2.04; P=0.064) compared with controls. Subgroup analysis according to treatment TAs showed that the addition of antiepidermal growth factor receptor (EGFR) agents to chemotherapy in GEC significantly improved the CR rate in comparison with control (Peto OR 1.77; 95% CI, 1.02–3.09; P=0.044), but not for other molecular TAs (P=0.49 for angiogenesis inhibitors, P=0.66 for mesenchymal-epithelial transition inhibitors). We also found that the addition of TAs to first-line therapy (Peto OR 1.41; 95% CI, 0.94–2.11; P=0.098) had a tendency to increase the chance of obtaining a CR, but not for second-line therapy (Peto OR 1.47; 95% CI, 0.60–3.55; P=0.40). In addition, correlation analysis indicates that PFS, ORR, and DCR were strongly correlated with OS for GEC patients receiving TAs (r=0.85 for PFS; r=0.86 for ORR; r=0.81 for DCR). No marked correlation was found between OS and CRs (r=0.43; P=0.18).

Conclusion

Although the CR is a rate event in advanced GEC patients, adding the TAs to therapies, especially for anti-EGFR agents, increases the chance of archiving CR in comparison with the controls. PFS, ORR, and DCR are significantly correlated with OS and could be used as surrogate endpoints in patients with GEC who have received TA therapy, but not for CR.

Antitumor evaluation of novel phenothiazine derivatives that inhibit migration and tubulin polymerization against gastric cancer MGC-803 cells

Two novel series of 1,2,3-triazole-phenothiazine hybrids and dithiocarbamate-phenothiazine hybrids were designed and synthesized by molecular hybridization strategy. Their antiproliferative activity against three gastric cancer cell lines (MKN28, MGC-803 and MKN45) were evaluated. Among them, hybrid 13h displayed the most potent inhibitory activity against gastric cancer MGC-803 cells with an IC₅₀ value of 1.2 μM. Hybrid 13h could inhibit migration by regulating the expression level of N-cadherin, E-cadherin, Vimentin, and actived-MMP2. Furthermore, it could regulate wnt/β-catenin signaling pathway on MGC-803 cells in a concentration-dependent manner by decreasing the expression level of Wnt5α, β-catenin and TCF4. From the tubulin polymerization assay results in vitro, hybrid 13h was a novel tubulin polymerization inhibitor. By oral administration assay, compound 13h could effectively inhibit MGC-803 xenograft tumor growth in vivo without obvious side effects. In summary, compound 13h might be an orally active antitumor agent with clinical applications to the treatment of gastric cancer. Graphical abstract Antitumor mechanisms of novel phenothiazine derivative.

Knockdown of A-kinase anchor protein 4 inhibits hypoxia-induced epithelial-to-mesenchymal transition via suppression of the Wnt/β-catenin pathway in human gastric cancer cells

Hypoxia induces epithelial-mesenchymal transition (EMT) in tumorigenesis. A-kinase anchor protein 4 (AKAP4) is a member of AKAPs family and plays a critical role in tumorigenesis. However, the biological role of AKAP4 in gastric cancer remains unknown. Thus, we investigated the effect of AKAP4 on EMT in human gastric cancer cells under hypoxic conditions. Our results showed that AKAP4 expression was significantly upregulated in human gastric cancer cell lines. In addition, silenced expression of hypoxia-inducible factor-1α markedly suppressed AKAP4 expression in gastric cancer cells under hypoxia. Furthermore, knockdown of AKAP4 significantly prevented hypoxia-induced migration, invasion, and EMT process in gastric cancer cells. Mechanistically, knockdown of AKAP4 prevented the activation of the Wnt/β-catenin pathway in gastric cancer cells under hypoxia condition. These findings indicate that knockdown of AKAP4 inhibits hypoxia-induced EMT in human gastric cancer cells, at least in part, via inactivation of the Wnt/β-catenin signaling pathway. It is, therefore, AKAP4 may be a potential therapeutic target for the treatment of gastric cancer.

Efficacy and safety of targeting VEGFR drugs in treatment for advanced or metastatic gastric cancer: a systemic review and meta-analysis

The value of targeting VEGFR (vascular endothelial growth factor receptor) drugs has demonstrated encouraging anti-cancer activity in advanced solid tumors within current clinical trials. This study aimed to serve as the first systemic review to assess their safety and efficacy according to biochemical characteristics of targeting VEGFR drugs in gastric cancer. We analyzed eight clinical trials on targeting VEGFR drugs in gastric cancer. Results showed that targeting VEGFR drugs significantly improved overall survival (OS) [Hazard Ratio (HR) 0.69, 95% confidence interval (CI) (0.55, 0.83), P < 0.001], progression free survival (PFS) [HR 0.50, 95% CI (0.34, 0.66), P < 0.001], disease control rate (DCR) [Odds Ratio (OR) 3.83, 95% CI (2.39, 6.15), P < 0.001] and significantly decreased the progressive disease rate(PDR)[OR 0.45, 95% CI (0.34, 0.59), P < 0.001], but not objective response rate (ORR) [OR 1.46, 95% CI (0.93, 2.29), P = 0.098]. Further subgroup revealed that VEGFR antibody (VEGFR-Ab) drugs were superior to VEGFR tyrosine kinase inhibitor (VEGFR-TKI) drugs in terms of the OS, PFS and PDR. To determine the toxic effect of targeting VEGFR drugs, the relative risk of adverse events (grade ≥ 3) of special interest(AESIs) were estimated. Most of these were predictable and manageable. Furthermore, less AESIs were observed in the VEGFR-Ab than the VEGFR-TKI drugs. In conclusion, VEGFR drugs were effective targeted therapy in advanced or metastatic gastric cancer, and its toxicity is within a controllable range. VEGFR-Ab drugs were more effective than VEGFR-TKI drugs in terms of the OS, PFS and PDR of gastric cancer patients with little toxicity.

C-reactive protein/albumin and neutrophil/lymphocyte ratios and their combination predict overall survival in patients with gastric cancer

Multiple studies have reported the prognostic association of certain inflammatory factors with various types of cancer. The present study assessed the prognostic value of the C-reactive protein (CRP)/albumin (Alb) ratio and the neutrophil/lymphocyte ratio (NLR), separately and in combination, in gastric cancer (GC). A total of 337 cases pathologically diagnosed with gastric adenocarcinoma were retrospectively evaluated. The clinicopathological and prognostic relevance of the CRP/Alb ratio and NLR and their combination were analyzed. The optimal cut-off values of the CRP/Alb ratio and NLR were 0.38 and 3.14, respectively. High CRP/Alb ratio (≥0.38) and NLR (≥3.14) values were associated with increased tumor invasion, more distant metastasis and a more advanced tumor-node-metastasis stage (all P<0.05). In addition, a high NLR value was also associated with increased tumor size (P=0.02). The CRP/Alb ratio (≥0.38/<0.38) and NLR (≥3.14/<3.14) were independent prognostic factors for overall survival time (OS) in GC by multivariate analysis (P=0.005 and P=0.001). Using the CRP/Alb ratio and NLR classification, patients were stratified into three subgroups with different OS time (P<0.001), which were identified as independent prognostic variables in multivariate analysis (P<0.001). The present study demonstrated that the CRP/Alb ratio and NLR were independent prognostic factors for OS in patients with GC. The combination of these indexes was associated with significant prognostic value and may further stratify prognosis.

Expression and function of transforming growth factor‑β‑activated protein kinase 1 in gastric cancer

The present study aimed to investigate the expression and role of transforming growth factor (TGF) ‑β‑activated protein kinase 1 (TAK1) in human gastric cancer. Immunohistochemistry was performed to investigate the expression of TAK1 in surgical specimens of human gastric cancer tissue and adjacent normal tissue. The association between TAK1 and clinicopathologic factors was analyzed and the association between TAK1 expression and the overall survival rates was evaluated using Kaplan‑Meier curves. In addition, the effect of the TAK1 selective inhibitor 5Z‑7‑oxozeaenol (OZ) on the biological characteristics of MGC803 human gastric cancer cells in vitro were investigated. The role of TAK1 in gastric cancer cell proliferation, apoptosis and invasion were determined by cell proliferation assays, flow cytometry analysis and transwell invasion assays, respectively. The findings of the present study demonstrated that the positive expression rate of TAK1 in gastric cancer and adjacent normal tissues was 70.5 and 25.9%, respectively. Furthermore, TAK1 expression was significantly associated with advanced N stage and pathological stage (P<0.05). Survival analysis of 139 patients with gastric cancer indicated a lower overall survival rate of patients in the TAK1‑positive group compared with the TAK1‑negative group (P<0.05). In addition, treatment with the TAK1 selective inhibitor OZ reduced the proliferation and invasion abilities of MGC803 cells and significantly reduced the expression levels of phosphorylated‑TAK1 (Thr187), nuclear p65, cyclin D1, Bcl‑2 apoptosis regulator and matrix metallopeptidase (MMP)9 (P<0.05). OZ treatment significantly increased the expression levels of cytosolic cytochrome c and cleaved caspase 3 and the apoptosis rate in MGC803 cells (P<0.05). In conclusion, these findings suggest that increased TAK1 expression may be involved in the progression of gastric cancer; therefore, TAK1 may be used as a future therapeutic target for gastric cancer treatment.

Clinical Significance of Preoperative Albumin and Globulin Ratio in Patients with Gastric Cancer Undergoing Treatment

Background. The pretreatment albumin and globulin ratio (AGR) was an inflammation-associated factor which was related to the overall survival in various malignancies. The aim of this study was to evaluate the prognostic value of AGR in patients with gastric cancer. Method. This retrospective study included 862 cases pathologically diagnosed with gastric cancer. All patients were randomly divided into the testing group (431 cases) and validation group (431 cases). The relationships of AGR with clinicopathologic characteristics and prognosis were analyzed by Kaplan-Meier and Cox regression methods. Results. In the testing group, the median overall survival was 26.90 months and the cutoff value of AGR was 1.50 based on R language. Kaplan-Meier analysis showed that lower AGR was correlated with poorer overall survival. Multivariate analysis demonstrated that AGR was an independent prognostic factor for overall survival (HR: 0.584, 95% CI = 0.351–0.973, and p = 0.039). In the validation group, the median overall survival was 24.10 months. Lower AGR (≤1.50) also had a significantly poorer overall survival by Kaplan-Meier analysis. According to multivariate analysis, the AGR was also confirmed to be an independent prognostic factor for overall survival (HR: 0.578, 95% CI = 0.373–0.897, and p = 0.015). Conclusions. Our study suggested that the pretreatment AGR could be a prognostic biomarker for overall survival in patients with gastric cancer.

Conversion Surgery for Patients With Stage IV HER2-Positive Gastric Cancer: A Report of 3 Patients

Gastric cancer is a common malignancy and remains potentially lethal. The prognosis of patients with stage IV gastric cancer is thought to be poor, but new molecular targeted therapy may benefit patients with advanced gastric cancer. Currently, conversion surgery after chemotherapy with a trastuzumab-containing regimen is reported to be effective in these patients. We present 3 patients with human epidermal growth factor receptor 2 (HER2)–positive advanced gastric cancer who underwent conversion surgery after receiving a trastuzumab-containing chemotherapy regimen. Interestingly, the primary lesion acquired resistance to the trastuzumab-containing regimen, although the metastatic lesions maintained a complete response. The reason why the primary lesions became resistant to trastuzumab remains unclear. More studies are needed to clarify the mechanism of resistance. Conversion surgery, made possible by the use of molecular-targeted therapy, may improve the prognosis of patients with stage IV gastric cancer, particularly if metastatic lesions show a complete response to therapy.

MiR-29 modulates multidrug resistance of gastric cancer cells by targeting Mcl-1

AIM

To investigate the differential expression of miR-29 in SGC7901/vincristine (VCR), SGC7901/adriamycin (ADR) and SGC7901 gastric cancer cell lines, and to explore its role in multidrug resistance of gastric cancer cells and the possible mechanism involved.

METHODS

qRT-PCR was used to detect the expression of miR-29 in different gastric cancer cell lines. After up- or down-regulation of miR-29 expression, MTT assay was applied to detect the changes in drug sensitivity (IC₅₀) of different gastric cancer cell lines. Apoptosis and cell cycle arrest were analyzed by flow cytometry. Western blot analysis and luciferase assay were performed to investigate the possible mechanism involved.

RESULTS

The expression levels of the miR-29 family members (miR-29a/b/c) in SGC7901/VCR and SGC7901/ADR cell lines were significantly lower than those in parental SGC7901 cells (P < 0.05). MTT assay showed that down-regulation of miR-29 led to a significant increase in the drug sensitivity (IC₅₀) of SGC7901 cells, while up-regulation of miR-29 induced a significant decrease in the drug sensitivity (IC₅₀) of SGC7901/VCR and SGC7901/ADR cells (P < 0.05). Flow cytometry analysis indicated that altered miR-29 expression caused significant changes in 5-fluorouridine induced apoptosis (P < 0.05). Western blot analysis and luciferase assay demonstrated that in gastric cancer cells myeloid cell leukemia-1 (Mcl-1) is the direct functional target of miR-29.

CONCLUSION

MiR-29 modulates multidrug resistance of gastric cancer cells by directly targeting the expression of anti-apoptotic Mcl-1.