Potential prognostic, diagnostic and therapeutic markers for human gastric cancer

Construction of an immune-related risk score signature for gastric cancer based on multi-omics data

Early identification of gastric cancer (GC) is associated with a superior survival rate compared to advanced GC. However, the poor specificity and sensitivity of traditional biomarkers suggest the importance of identifying more effective biomarkers. This study aimed to identify novel biomarkers for the prognosis of GC and construct a risk score (RS) signature based on these biomarkers, with to validation of its predictive performance. We used multi-omics data from The Cancer Genome Atlas to analyze the significance of differences in each omics data and combined the data using Fisher's method. Hub genes were subsequently subjected to univariate Cox and LASSO regression analyses and used to construct the RS signature. The RS of each patient was calculated, and the patients were divided into two subgroups according to the RS. The RS signature was validated in two independent datasets from the Gene Expression Omnibus and subsequent analyses were subsequently conducted. Five immune-related genes strongly linked to the prognosis of GC patients were obtained, namely CGB5, SLC10A2, THPO, PDGFRB, and APOD. The results revealed significant differences in overall survival between the two subgroups (p < 0.001) and indicated the high accuracy of the RS signature. When validated in two independent datasets, the results were consistent with those in the training dataset (p = 0.003 and p = 0.001). Subsequent analyses revealed that the RS signature is independent and has broad applicability among various GC subtypes. In conclusion, we used multi-omics data to obtain five immune-related genes comprising the RS signature, which can independently and effectively predict the prognosis of GC patients with high accuracy.

Role of Angiogenesis and Its Biomarkers in Development of Targeted Tumor Therapies

Angiogenesis plays a significant role in the human body, from wound healing to tumor progression. "Angiogenic switch" indicates a time-restricted event where the imbalance between pro- and antiangiogenic factors results in the transition from prevascular hyperplasia to outgrowing vascularized tumor, which eventually leads to the malignant cancer progression. In the last decade, molecular players, i.e., angiogenic biomarkers and underlying molecular pathways involved in tumorigenesis, have been intensely investigated. Disrupting the initiation and halting the progression of angiogenesis by targeting these biomarkers and molecular pathways has been considered as a potential treatment approach for tumor angiogenesis. This review discusses the currently known biomarkers and available antiangiogenic therapies in cancer, i.e., monoclonal antibodies, aptamers, small molecular inhibitors, miRNAs, siRNAs, angiostatin, endostatin, and melatonin analogues, either approved by the U.S. Food and Drug Administration or currently under clinical and preclinical investigations.

Prognostic significance of metastatic lymph node ratio in gastric cancer: a Western-center analysis

BACKGROUND

Tumor-node-metastasis (TNM) staging is the central gastric cancer (GC) staging system, but it has some disadvantages. However, the lymph node ratio (LNR) can be used regardless of the type of lymphadenectomy and is considered an important prognostic factor. This study aimed to evaluate the relationship between LNR and survival in patients who underwent curative GC surgery.

METHODS

All patients who underwent radical gastric surgery between January 2014 and June 2022 were retrospectively evaluated. Clinicopathological features of tumors, TNM stage, and survival rates were analyzed. LNR was defined as the ratio between metastatic lymph nodes and total lymph nodes removed. The LNR groups were classified as follows: LNR0 = 0, 0.01 < LNR1 ≤ 0.1, 0.1 < LNR2 ≤ 0.25 and LNR3 > 0.25. Tumor characteristics and overall survival (OS) of the patients were compared between LNR groups.

RESULTS

After exclusion, 333 patients were analyzed. The mean age was 62 ± 14 years. According to the LNR classification, no difference was found between groups regarding age and sex. However, TNM stage III disease was significantly more common in LNR3 patients. Most patients (43.2%, n = 144) were in the LNR3 group. In terms of tumor characteristics (lymphatic, vascular, and perineural invasion), the LNR3 group had significantly poorer prognostic factors. The Cox regression model defined LNR3, TNM stage II-III disease, and advanced age as independent risk factors for survival. Patients with LNR3 demonstrated the lowest 5-year OS rate (35.7%) (estimated mean survival was 30 ± 1.9 months) compared to LNR 0-1-2.

CONCLUSION

Our study showed that a high LNR was significantly associated with poor OS in patients who underwent curative gastrectomy. LNR can be used as an independent prognostic predictor in GC patients.

Clinical value of serum Mg7-Ag detection combined with magnifying endoscopy with narrow-band imaging in diagnosis of high-risk gastric low-grade intraepithelial neoplasia

BACKGROUND

Human gastric cancer associated antigen (Mg7-Ag) can be highly expressed in gastric cancer cell lines, and is closely related to gastric cancer progression. Magnifying endoscopy with narrow-band imaging (ME-NBI) has high sensitivity and specificity in the diagnosis of early gastric cancer, especially for differentiated gastric cancer. This study assessed the clinical diagnostic value of serum Mg7-Ag detection combined with ME-NBI for high-risk low grade intraepithelial neoplasia (LGIN).

AIM

To evaluate the clinical value of serum Mg7-Ag detection combined with ME-NBI in judging whether there is pathological upgrading of gastric LGIN after endoscopic dissection (ESD).

METHODS

Patients who were diagnosed with LGIN at our hospital from January 2019 to December 2022 and underwent diagnostic ESD within 1 mo were selected and divided into a high-risk group (pathologically upgraded), a low-risk group (pathologically not upgraded), and an inflammation group (pathologically downgraded) according to the differences in pathological results after ESD and preoperative endoscopic biopsy. Serum Mg7-Ag levels were detected in all cases within 1 week before ESD, and gastroscopic ME-NBI screening was performed. The levels of serum Mg7-Ag, the number of Mg7-Ag (+) and Mg7-Ag (-) patients, and the number of ME-NBI (+) and ME-NBI (-) patients in the three groups were recorded. The sensitivity, specificity, accuracy, and positive likelihood ratio of serum Mg7-Ag and ME-NBI, alone and in combination, for predicting pathological upgrading after ESD of LGIN lesions were calculated and analyzed.

RESULTS

A total of 125 patients with gastric LGIN who underwent diagnostic ESD were included in this study, including 37 in the high-risk group, 76 in the low-risk group, and 12 in the inflammation group. Serum Mg7-Ag levels were significantly different among the three groups (P < 0.05), and Mg7-Ag levels in the high-risk group were significantly higher than those in the low-risk group and the inflammation group (P < 0.05). The positive rate of ME-NBI in the inflammation group was significantly lower than those in the other two groups (P < 0.05), and the rate in the high-risk group was higher than that in the low-risk group (P < 0.05). There was no significant difference in the sensitivity, specificity, accuracy, and positive likelihood ratio of Mg7-Ag and ME-NB alone in predicting the pathological upgrading of LGIN (P > 0.05). The sensitivity of combined Mg7-Ag detection and ME-NBI in predicting high-risk LGIN was slightly lower than that of either of them alone; the specificity was 90.5%, the accuracy was 84.0%, and the positive likelihood ratio was 2.417, all of which were significantly higher than those of single tests (P < 0.05). When Mg7-Ag + ME-NBI results were negative, the accuracy and positive likelihood for cases in the inflammation group were significantly higher than those of single tests (P < 0.05).

CONCLUSION

Combined serum Mg7-Ag detection and ME-NBI screening has important clinical value in judging whether gastric LGIN lesions will undergo pathological upgrading.

PharmaKoVariome database for supporting genetic testing

Pharmacogenomics (PGx) provides information about routine precision medicine, based on the patient's genotype. However, many of the available information about human allele frequencies, and about clinical drug-gene interactions, is based on American and European populations. PharmaKoVariome database was constructed to support genetic testing for safe prescription and drug development. It consolidated and stored 2507 diseases, 11 459 drugs and 61 627 drug-target or druggable genes from public databases. PharmaKoVariome precomputed ethnic-specific abundant variants for approximately 120 M single-nucleotide variants of drug-target or druggable genes. A user can search by gene symbol, drug name, disease and reference SNP ID number (rsID) to statistically analyse the frequency of ethnical variations, such as odds ratio and P-values for related genes. In an example study, we observed five Korean-enriched variants in the CYP2B6 and CYP2D6 genes, one of which (rs1065852) is known to be incapable of metabolizing drug. It is also shown that 4-6% of North and East Asians have risk factors for drugs metabolized by the CYP2D6 gene. Therefore, PharmaKoVariome is a useful database for pharmaceutical or diagnostic companies for developing diagnostic technologies that can be applied in the Asian PGx industry. Database URL: http://www.pharmakovariome.com/.

Molecular and Circulating Biomarkers of Gastric Cancer

Gastric cancer (GC)—a common tumor that affects humans worldwide—is highly malignant with a poor prognosis. GC is frequently not diagnosed until a relatively advanced stage. Early detection and efficient monitoring of tumor dynamics are prerequisites for reducing disease burden and mortality. Minimally invasive methods are needed to establish a diagnosis or monitoring the response to treatment of gastric cancer. Blood-based biomarker assays for the detection of early-stage GC could be of great relevance both for the risk group or for population-wide based screening programs, The currently used tumor marker assays for detecting GC are simple and rapid, but their use is limited by their low sensitivity and specificity. In recent years, several markers have been identified and tested for their clinical relevance in the management of gastric cancer. Here we review the available literature on plasma classical tumor markers, circulating free microRNAs (cfmiRNAs), circulating cell-free DNA (cfDNA), circulating tumor cells (CTCs), autoantibodies against tumor associated antigens (TAAs), and circulating extracellular vesicles (EVs) for diagnosis and monitoring of gastric cancer. This review summarizes the present status and approaches for these biomarkers, which could be potentially used for early diagnosis and accurate prediction of therapeutic approaches. We also discuss the future perspective and challenges in the search for new biomarkers of gastric cancer.

Detection of serum Mg7-Ag, CEA and pepsinogens combined with magnifying narrow-band imaging endoscopy for screening early gastric carcinoma in high risk patients

AIM

To assess the clinical value of serum Mg7-Ag, carcinoembryonic antigen (CEA), pepsinogen (PG) I, PGⅡ and PGI/PGⅡ ratio (PGR) combined with magnifying narrow-band imaging endoscopy (ME-NBI) for screening early gastric cancer (GC) in high-risk patients.

METHODS

A total of 802 patients at a high risk for GC were selected for the study. ELISA was used to detect serum Mg7-Ag, PGI, PGII, and CEA levels, and the PGR was calculated. According to the results, the patients were categorized as Mg7-Ag (+) and Mg7-Ag (-), PGI (+) and PGI (-), PGR (+) and PGR (-), and CEA (+) and CEA (-). Gastroscopy was performed for all enrolled patients, and gastric lesions were examined by ME-NBI and pathological examination was performed. According to the pathological results, the patients were divided into an inflammatory group, a precancerous disease group, an atypical hyperplasia group, an early GC group and an advanced GC group. Serum Mg7-Ag, PGI and PGR values and the number of patients with positive results were compared among different groups, and the sensitivity, specificity and accuracy of these indexes, alone or in combination, for early diagnosis of GC were calculated.

RESULTS

Serum level of PGI in the non-inflammatory group was significantly lower than that in the simple inflammatory group (P < 0.05). Serum levels of Mg7-Ag and CEA in the GC group were significantly higher than those in the non-GC group (P < 0.05). However, serum level of Mg7-Ag in the early GC group was not significantly different from that in the advanced GC group, while serum CEA level of the advanced GC group was significantly higher than that in the early GC group (P < 0.05). The sensitivity of Mg7-Ag combined with ME-NBI for diagnosing early GC was significantly higher than that of PGR and PGI (P < 0.05), but there was no significant difference in specificity between each group (P > 0.05). The accuracy of CEA in the diagnosis of GC was the lowest, and the accuracy of Mg7-Ag and ME-NBI detection was significantly higher than that of PGR and PGI. The sensitivity and accuracy of combined detection of PGI + PGR, PGI + PGR + Mg7-Ag, and PGI + PGR + Mg7-Ag + ME-NBI increased gradually, while there was no significant difference in specificity (P > 0.05). Positive result of PGI + PGR + Mg7-Ag + ME-NBI combined with CEA (-) had significantly higher sensitivity and accuracy than PGI + PGR + Mg7-Ag + ME-NBI (P < 0.05), although there was no significant difference in specificity (P > 0.05).

CONCLUSION

Combined detection of serum Mg7-Ag, PG and CEA plus ME-NBI examination is of great clinical significance for screening early GC in highly suspicious people.

Corosolic acid reduces 5‑FU chemoresistance in human gastric cancer cells by activating AMPK

5‑Fluorouracil (5‑FU) is one of the most commonly used chemotherapeutic agents for gastric cancer. Resistance to 5‑FU‑based chemotherapy remains the major obstacle in the treatment of gastric cancer. A growing body of evidence has suggested that adenosine monophosphate‑activated protein kinase (AMPK) is pivotal for chemoresistance. However, the mechanism by which AMPK regulates the chemosensitivity of gastric cancer remains unclear. In the present study, how corosolic acid enhanced the chemosensitivity of gastric cancer cells to 5‑FU via AMPK activation was investigated. A 5‑FU‑resistant gastric cancer cell line (SNU‑620/5‑FUR) was established, which had a marked increase in thymidine synthase (TS) expression but reduced AMPK phosphorylation when compared with the parental cell line, SNU‑620. AMPK regulation by 5‑aminoimidazole‑4‑carboxamide ribonucleotide or compound c was revealed to be markedly associated with TS expression and 5‑FU‑resistant cell viability. In addition, corosolic acid activated AMPK, and decreased TS expression and the phosphorylation of mammalian target of rapamycin/4E‑binding protein 1 in a dose‑dependent manner. Corosolic acid treatment significantly reduced cell viability while compound c reversed corosolic acid‑induced cell growth inhibition. The 5‑FU‑resistance sensitization effect of corosolic acid was determined by the synergistic reduction of TS expression and inhibition of cell viability in the presence of 5‑FU. The corosolic acid‑induced AMPK activation was markedly increased by additional 5‑FU treatment, while compound c reversed AMPK phosphorylation. In addition, compound c treatment reversed corosolic acid‑induced apoptotic markers such as capase‑3 and PARP cleavage, and cytochrome c translocation to cytosol, in the presence of 5‑FU. Corosolic acid treatment in the presence of 5‑FU induced an increase in the apoptotic cell population based on flow cytometry analysis. This increase was abolished by compound c. In conclusion, these results implied that corosolic acid may have therapeutic potential to sensitize the resistance of gastric cancer to 5‑FU by activating AMPK.

Systematic literature review of IL-6 as a biomarker or treatment target in patients with gastric, bile duct, pancreatic and colorectal cancer

Gastrointestinal cancer (GI) is a major health problem. Patients with gastric, pancreatic, colorectal, bile duct and gall bladder cancer often have advanced disease at the time of diagnosis and are generally difficult to cure, resulting in a dismal prognosis for most patients. Inflammation plays an important role in the development and growth of cancer, which has led to a growing interest in the pro-inflammatory cytokine interleukin 6 (IL-6). The aim of the present review was to evaluate the clinical use of IL-6 as a biomarker or therapeutic target in patients with GI cancer. We did a systematic review of studies (1993-2018), to assess the clinical use of IL-6 as a diagnostic, prognostic or predictive tumor biomarker or as a potential therapeutic target. This review includes 48 studies and 5316 patients. Circulating IL-6 levels appear to be an independent prognostic biomarker in patients with GI cancer, with high IL-6 levels associated with short overall survival (OS). The results for colorectal cancer were too ambiguous to give conclusive results. IL-6 seemed to be a marker for some of the clinical characteristics of GI cancer, and may have a role in the diagnostic workup in general practice. No published studies have examined the use of IL-6 as a therapeutic target in pancreatic, gastric, bile duct or colorectal cancer. In conclusion, high circulating IL-6 was associated with short OS in most studies in GI cancer patients. Whether inhibition of IL-6 would decrease GI cancer symptoms and increase quality of life is unknown.

Identification of serum proteins AHSG, FGA and APOA-I as diagnostic biomarkers for gastric cancer

Background

The development of clinically accessible biomarkers is critical for the early diagnosis of gastric cancer (GC) in patients. High-throughput proteomics techniques could not only effectively generate a serum peptide profile but also provide a new approach to identify potentially diagnostic and prognostic biomarkers for cancer patients.

Methods

In this study, we aim to identify potentially discriminating serum biomarkers for GC. In the discovery cohort, we screened potential biomarkers using magnetic-bead-based purification and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry in 64 samples from 32 GC patients that were taken both pre- and post-operatively and 30 healthy volunteers that served as controls. In the validation cohort, the expression patterns and diagnostic values of serum FGA, AHSG and APOA-I were further confirmed by ELISA in 42 paired GC patients (pre- and post-operative samples from 16 patients with pathologic stage I/II and 26 with stage III/IV), 30 colorectal cancer patients, 30 hepatocellular carcinoma patients, and 28 healthy volunteers.

Results

ClinProTools software was used and annotated 107 peptides, 12 of which were differentially expressed among three groups (P < 0.0001, fold > 1.5). These 12 peptide peaks were further identified as FGA, AHSG, APOA-I, HBB, TXNRD1, GSPT2 and CAKP5. ELISA data suggested that the serum levels of FGA, AHSG and APOA-I in GC patients were significantly different compared with healthy controls and had favorable diagnostic values for GC patients. Moreover, we found that the serum levels of these three proteins were associated with TNM stages and could reflect tumor burden.

Conclusion

Our findings suggested that FGA, AHSG and APOA-I might be potential serum biomarkers for GC diagnosis.

Recent advances in mass spectrometry-based proteomics of gastric cancer

The last decade has witnessed remarkable technological advances in mass spectrometry-based proteomics. The development of proteomics techniques has enabled the reliable analysis of complex proteomes, leading to the identification and quantification of thousands of proteins in gastric cancer cells, tissues, and sera. This quantitative information has been used to profile the anomalies in gastric cancer and provide insights into the pathogenic mechanism of the disease. In this review, we mainly focus on the advances in mass spectrometry and quantitative proteomics that were achieved in the last five years and how these up-and-coming technologies are employed to track biochemical changes in gastric cancer cells. We conclude by presenting a perspective on quantitative proteomics and its future applications in the clinic and translational gastric cancer research.

A long non-coding RNA signature to improve prognosis prediction of gastric cancer

BACKGROUND

Increasing evidence suggests long non-coding RNAs (lncRNAs) are frequently aberrantly expressed in cancers, however, few related lncRNA signatures have been established for prediction of cancer prognosis. We aimed at developing alncRNA signature to improve prognosis prediction of gastric cancer (GC).

METHODS

Using a lncRNA-mining approach, we performed lncRNA expression profiling in large GC cohorts from Gene Expression Ominus (GEO), including GSE62254 data set (N = 300) and GSE15459 data set (N = 192). We established a set of 24-lncRNAs that were significantly associated with the disease free survival (DFS) in the test series.

RESULTS

Based on this 24-lncRNA signature, the test series patients could be classified into high-risk or low-risk subgroup with significantly different DFS (HR = 1.19, 95 % CI = 1.13-1.25, P < 0.0001). The prognostic value of this 24-lncRNA signature was confirmed in the internal validation series and another external validation series, respectively. Further analysis revealed that the prognostic value of this signature was independent of lymph node ratio (LNR) and postoperative chemotherapy. Gene set enrichment analysis (GSEA) indicated that high risk score group was associated with several cancer recurrence and metastasis associated pathways.

CONCLUSIONS

The identification of the prognostic lncRNAs indicates the potential roles of lncRNAs in GC biogenesis. Our results may provide an efficient classification tool for clinical prognosis evaluation of GC.

Tristetraprolin inhibits gastric cancer progression through suppression of IL-33

Tristetraprolin (TTP) is an adenine/uridine (AU)-rich element (ARE)-binding protein that can induce degradation of mRNAs. In this study, we report that TTP suppresses the expression of interleukin-33 (IL-33), a tumor-promoting inflammatory cytokine, and thereby inhibits the progression of gastric cancer (GC). Overexpression of TTP decreased the level of IL-33, whereas knockdown of TTP increased IL-33 levels. We also discovered that TTP inhibited the proliferation, migration, and invasion of GC cell lines through regulation of IL-33. Furthermore, TTP RNA and protein levels were remarkably reduced in GC and inversely correlated with IL-33 level, and they were also closely associated with depth of invasion, lymph node metastasis, advanced TNM stage, as well as survival rate. Taken together, these findings identified TTP as a downregulator of IL-33, and further suggest that TTP can serve as a novel biomarker for the diagnosis of GC and as a potential therapeutic target for GC treatment.

Potential Biomarkers in Diagnosis of Human Gastric Cancer

The high incidence of gastric cancer (GC) and its consequent mortality rate severely threaten human's health. It is not frequently diagnosed until a relatively advanced stage. Surgery is the only potentially curative treatment. Thus, early screening and diagnosis are critical for patients with GC. The tumor marker assays used currently for detecting GC are simple and rapid, but the usage is limited by its low sensitivity and specificity. Here, we provide a brief description of some new potential markers and new biotechnological methods for the diagnosis of GC, hoping to find out more effective approaches for early detection of GC.

Upregulated long intergenic noncoding RNA KRT18P55 acts as a novel biomarker for the progression of intestinal-type gastric cancer

Background

Long noncoding RNAs (lncRNAs) with dysregulated expression levels have been investigated in numerous types of different cancer. Whether lncRNAs can predict the progression of gastric cancer (GC) still remains largely unclear. The aim of our study was to investigate whether KRT18P55, a novel intergenic lncRNA, can be a predictive biomarker for GC.

Methods

To determine the expression levels of KRT18P55 in GC, we evaluated it in five GC cell lines (SGC-7901, MGC-803, BGC-823, AGS, and HG27) and 97 GC tissue samples in comparison with a normal control by quantitative polymerase chain reaction. In addition, the association with patient clinicopathological characteristics was analyzed to identify the clinical significance of KRT18P55. We also used publicly accessible data from The Cancer Genome Atlas (TCGA) to further verify the expression levels and clinical significance of KRT18P55. Furthermore, a receiver operating characteristic curve was also conducted to evaluate the diagnostic value of KRT18P55 for GC.

Results

A significant upregulation was observed in GC cell lines (P<0.01) and tissue samples (P<0.01). This finding was consistent with the results of 29 pairs of GC tissue samples from TCGA (P<0.01). Additionally, we indicated that the increased expression of KRT18P55 was related to the progression of intestinal type (P=0.032), which was also supported by results of independent GC cohorts from TCGA (P<0.01). However, we did not find significant difference in prognosis between patients with high and low expression of KRT18P55 (P>0.05). Finally, KRT18P55 showed potential diagnostic value for GC with an area under the receiver operating characteristic curve of 0.733 (P<0.01).

Conclusion

Upregulated KRT18P55 was a novel biomarker for the progression of GC, especially for the intestinal type.

Methylation status of TRAF2 is associated with the diagnosis and prognosis of gastric cancer

The purpose was to investigate whether the expression level of TRAF2 gene was regulated by DNA methylation and explore the role of TRAF2 methylation in the diagnosis and prognosis of gastric cancer (GC). Firstly, we detected the expression of TRAF2 both at mRNA level and protein level. And the up-regulated of TRAF2 expression at two different levels were both found (P<0.001). Then we measured the methylated status of TRAF2 by MSP and got a result of that TRAF2 was hypomethylated in GC patients compared with healthy controls (P<0.001). Meanwhile, the relationship between TRAF2 methylation and clinicopathologic characteristics was estimated through chi-square. The outcome proved that TRAF2 methylation was impacted by age (P=0.024), lymph node metastasis (P=0.046), TNM stage (P=0.021), distant metastasis (P=0.002) and depth of invasion (P=0.002). The AUC of 0.795 accompanying a sensitivity of 66.7% and a specificity of 94.7% were obtained from Receiver Operating Characteristic (ROC) curve which indicated the diagnostic value of TRAF2 methylation was high. At last, we researched the prognostic value of TRAF2 methylation. Kaplan-Meier showed that patients with TRAF2 hypomethylation had lived much shorter than those with TRAF2 hypermethylation (log rank test, P<0.001). Cox regression analysis revealed TRAF2 hypomethylation (HR=18.827, 95% CI=3.103-114.222, P=0.001), lymph node metastasis (HR=0.154, 95% CI=0.047-0.512, P=0.002), distant metastasis (HR=3.032, 95% CI=1.116-8.237, P=0.030), as well as differentiation (HR=0.287, 95% CI=0.113-0.731, P=0.009) were all vital prognostic factors in GC. Taken together, TRAF2 expression was increased in GC patients by DNA hypomethylation and this methylation could be an independent diagnostic and prognostic indicator in GC.

AMPK activator AICAR promotes 5-FU-induced apoptosis in gastric cancer cells

The aim of the present study was to determine the effect of AICAR, an AMPK activator, on apoptosis in gastric carcinoma cells (SGC-7901) with or without 5-fluorouracil (5-FU). SGC-7901 cells were treated with AICAR (0.2-5 mM, for 24-48 h) with or without 5-FU. Cell viability was determined using MTT assay, while apoptosis were measured through the evaluation of active caspase-3 activity and DNA fragmentation. Real-time PCR was employed to determine the expression of tumor suppressor and multi-drug resistant (mdr1) gene. Cleaved caspase-3 and phosphorylated AMPK (p-AMPK) were measured by Western blot. AICAR significant reduced cellular viability but increased apoptosis in a time- and dose-dependent manner, which is associated with an increase in p-AMPK levels. Importantly, AICAR enhanced the sensitivity to 5-FU-induced reduction of cellular viability and increased apoptosis in SGC-7901 cells. Furthermore, AICAR increased tumor suppressor genes [F-box and WD repeat domain containing 7 (FBXW7), semaphorin III/F (SEMA3F), and p21(Cip1) (p21)] but reduced mdr1 expression. Finally, p-AMPK levels were reduced in 5-FU-resistant gastric cancer cells compared to human immortalized gastric epithelial cell line and 5-FU-sensitive gastric cancer cells. AICAR not only induces apoptosis alone but also enhances pro-apoptotic effect of 5-FU in SGC-7901 cells, which lays an experimental foundation to develop AICAR as a chemotherapeutic sensitizer against gastric cancer.

Cullin family proteins and tumorigenesis: genetic association and molecular mechanisms

Cullin family proteins function as scaffolds to form numerous E3 ubiquitin ligases with RING proteins, adaptor proteins and substrate recognition receptors. These E3 ligases further recognize numerous substrates to participate in a variety of cellular processes, such as DNA damage and repair, cell death and cell cycle progression. Clinically, cullin-associated E3 ligases have been identified to involve numerous human diseases, especially with regard to multiple cancer types. Over the past few years, our understanding of cullin proteins and their functions in genome stability and tumorigenesis has expanded enormously. Herein, this review briefly provides current perspectives on cullin protein functions, and mainly summarizes and discusses molecular mechanisms of cullin proteins in tumorigenesis.

Prognostic significance of combined microRNA-206 and CyclinD2 in gastric cancer patients after curative surgery: A retrospective cohort study

AIM

To investigate associations of microRNA (miR)-206 and CyclinD2 (CCND2) expression, alone or in combination, with clinicopathological characteristics and patients' prognosis in gastric cancer.

METHODS

MiR-206 and CCND2 mRNA expression levels were detected by real-time quantitative RT-PCR in 220 self-pairs of gastric cancer and adjacent non-cancerous tissues.

RESULTS

Compared with the adjacent non-cancerous tissues, the expression levels of miR-206 and CCND2 mRNA were respectively reduced and elevated in gastric cancer tissues dramatically (both P<0.001). Notably, the expression levels of miR-206 in gastric cancer tissues were negatively correlated with those of CCND2 mRNA significantly (r=-0.463, P<0.001). Then, statistical analysis showed that low miR-206 expression and high CCND2 expression, alone or in combination, were all significantly associated with great depth of invasion, positive lymph node and distant metastases, and advanced TNM stage of human gastric cancer (all P<0.05). After that, we also found that the overall survivals of the patients with low miR-206 expression and high CCND2 expression were respectively shorter than those with high miR-206 expression and low CCND2 expression. More interestingly, miR-206-low/CCND2-high expression was associated with a significantly worst overall survival of all miR-206/CCND2 groups (P<0.001). Furthermore, multivariate analysis identified miR-206 and/or CCND2 expression as independent prognostic factors for overall survival in patients with gastric cancer.

CONCLUSION

Our data provide evidence that the dysregulation of miR-206-CCND2 axis may contribute to the aggressive progression and poor prognosis of human gastric cancer in clinical settings. Combined detection of their expression might be particularly helpful for surveillance of disease progression and treatment stratification.

The photodynamic effect of far-red range phthalocyanines (AlPc and Pc green) supported by electropermeabilization in human gastric adenocarcinoma cells of sensitive and resistant type

INTRODUCTION

Electroporation (EP) is commonly applied for effective drug transport thorough cell membranes based on the application of electromagnetic field. When applied with cytostatics, it is called electrochemotherapy (ECT) - a quite new method of cancer treatment. A high-voltage pulse causes the formation of temporary pores in the cell membrane which create an additional way for the intracellular drug transport. In the current work, EP was effectively merged with the already known photodynamic therapy (PDT) to selective photosensitizers' delivery to diseased tissue. The application of electroporation can reduce the dose of applied drug.

RESEARCH OBJECTIVE

The aim of research was to evaluate the effectiveness of photodynamic reaction using two near infrared cyanines (AlPc and Pc green) combined with electroporation in two human gastric adenocarcinoma cell lines.

MATERIALS AND METHODS

Two human cell lines - EPG85-257P (parental) and EPG85-257RDB (resistant to daunorubicin) - of gastric cancer were used. The effect of two photosensitizers (aluminum 1,8,15,22-tetrakis(-phenylthio)-29H,31H-phthalocyanine chloride and Phthalocyanine green) was investigated. The efficiency of EP parameters was assessed by propidium iodide uptake. The viability assay was applied to analyse EP, PDT and EP-PDT effect. Cyanine localization was determined by confocal microscopy. Immunocytochemical evaluation of manganese superoxide dismutase and glutathione S-transferase-pi was determined after applied therapies.

RESULTS

PDT in combination with EP affected the viability of EPG85-257P and EPG85-257RDB cells negatively while both cyanine were used. The most evident changes were observed in the following concentrations: 15, 10 and 5μM. The optimal field strength for enhanced EP-PDT was 800 and 1200V/cm. AlPc distributed selectively in the lysosomes of parental cell line.

CONCLUSIONS

PDT, enhanced by EP, caused decreased viability when compared to the application of PDT alone. Both phthalocyanines found to be more effective after electroporation. Due to the low concentration of light-sensitive compounds and safety of electroporation itself, a treatment plan can be an alternative therapeutic modality against gastric adenocarcinomas.