Gene-gene interactions in gastrointestinal cancer susceptibility

Role of Metabolomics in Pathogenesis and Prompt Diagnosis of Gastric Cancer Metastasis-A Systematic Review

INTRODUCTION

Gastric cancer is the fourth most frequently diagnosed form of cancer and the third leading cause of cancer-related mortality worldwide. The aim of this review is to identify individual metabolic biomarkers and their association with accurate diagnostic values, which can predict gastric cancer metastasis.

MATERIALS AND METHODS

After searching the keywords, 83 articles were found over a period of 13 years. One was eliminated because it was not written in English, and two were published outside the selected period. Seven scientific papers were qualified for this investigation after eliminating duplicates, non-related articles, systematic reviews, and restricted access studies.

RESULTS

New metabolic biomarkers with predictive value for gastric cancer metastasis and for elucidating metabolic pathways of the metastatic process have been found. The pathogenic processes can be outlined as follows: pro-oxidant capacity, T-cell inactivation, cell cycle arrest, energy production and mitochondrial enzyme impairment, cell viability and pro-apoptotic effect, enhanced degradation of collagen extracellular matrix, migration, invasion, structural protein synthesis, and tumoral angiogenesis.

CONCLUSION

Metabolic biomarkers have been recognized as independent risk factors in the molecular process of gastric cancer metastasis, with good diagnostic and prognostic value.

Functional gene polymorphisms and expression alteration of selected microRNAs and the risk of various gastric lesions in Helicobacter pylori-related gastric diseases

Background: Helicobacter pylori (Hp) persistent infection is an important pathogenic factor for a series of chronic gastric diseases from chronic gastritis to gastric cancer. Genetic and epigenetic abnormalities of microRNAs may play a vital role in the pathological evolution of gastric mucosa in Helicobacter pylori-related gastric diseases (HPGD). This study aimed to investigate the relationship between miR-146a, miR-196a2, miR-149, miR-499 and miR-27a gene single nucleotide polymorphisms (SNPs) and their expressions with pathological changes in gastric mucosa, and to further analyze the interactions between SNPs and Hp. Methods: Subjects in this study included patients diagnosed with HPGD and healthy controls. MiR-146a rs2910164, miR-196a2 rs11614913, miR-149 rs2292832, miR-499 rs3746444 and miR-27a rs895819 were genotyped by direct sequencing. Fluorescence quantitative PCR was used to detect microRNA expressions. Gene-gene and gene-environment interactions were evaluated by multifactor dimensionality reduction (MDR) method. Results: we found that frequency distribution of miR-196a2 rs11614913 CT genotype in gastric precancerous lesion (GPL) group and gastric cancer (GC) group was significantly higher than normal control (NOR) group [adjusted OR = 6.16, 95%CI (1.46-26.03); adjusted OR = 11.83, 95%CI (1.65-84.72), respectively]. CT genotype and C allele of miR-27a rs895819 were associated with increased risk of GC [adjusted OR = 10.14, 95%CI (2.25-45.77); adjusted OR = 3.71, 95%CI(1.46-9.44), respectively]. The MDR analysis results showed that the interaction between miR-196a2 rs11614913 and Hp was associated with the risk of GPL (p = 0.004). Meanwhile, the expression level of miR-196a2 in GC group was significantly higher than NOR, chronic inflammation (CI) and early precancerous lesion (EPL) groups among Hp-positive subjects. And expressions of miR-499 and miR-27a in GC group were both higher than EPL group. Also, miR-27a expression in GC group was higher than CI and gastric atrophy (GA) groups. Conclusion: miR-196a2 rs11614913 and miR-27a rs895819 may affect the genetic susceptibility to GPL or GC. MiR-196a2 rs11614913 and Hp have a synergistic effect in the occurrence and development of GPL. The up-regulation of miR-499, miR-196a2 and miR-27a expression caused by Hp infection may be an important mechanism of gastric carcinogenesis.

The Role of Lipid Metabolism in Gastric Cancer

Gastric cancer has been one of the most common cancers worldwide with extensive metastasis and high mortality. Chemotherapy has been found as a main treatment for metastatic gastric cancer, whereas drug resistance limits the effectiveness of chemotherapy and leads to treatment failure. Chemotherapy resistance in gastric cancer has a complex and multifactorial mechanism, among which lipid metabolism plays a vital role. Increased synthesis of new lipids or uptake of exogenous lipids can facilitate the rapid growth of cancer cells and tumor formation. Lipids form the structural basis of biofilms while serving as signal molecules and energy sources. It is noteworthy that lipid metabolism is capable of inducing drug resistance in gastric cancer cells by reshaping the tumor micro-environment. In this study, new mechanisms of lipid metabolism in gastric cancer and the metabolic pathways correlated with chemotherapy resistance are reviewed. In particular, we discuss the effects of lipid metabolism on autophagy, biomarkers treatment and drug resistance in gastric cancer from the perspective of lipid metabolism. In brief, new insights can be gained into the development of promising therapies through an in-depth investigation of the mechanism of lipid metabolism reprogramming and resensitization to chemotherapy in gastric cancer cells, and scientific treatment can be provided by applying lipid-key enzyme inhibitors as cancer chemical sensitizers in clinical settings.

Independent and Interactive Effect of CYPs and GSTs Genetic Variants and Tobacco Smoking on the Risk of Non-Small Cell Lung Carcinoma

BACKGROUND

CYP and GST gene families detoxify tobacco carcinogens and have been linked to the risk of non-small cell lung carcinoma (NSCLC).

AIM

Independent and combined effects of CYP and GST genetic variations and smoking on the risk of non-small cell lung carcinoma (NSCLC) and its sub-histological types.

METHODS

We modelled an epistatic interaction via the effects of particular genotypes in two genes as OR (odds ratio), OR1, and OR2, a combination of both genotypes were characterized as OR_combine. In contrast, the two ORs' epistatic interaction for the individual genotypes has been represented as OR_interaction = OR_combine/(OR1 × OR2).

RESULTS

The variant genotypes of CYP2A6 (OR:4.2, p <0.001), GSTT1 (OR:3.9, p <0.001), and GSTM1 (OR: 4.5, p <0.001) were showed a significant risk with NSCLC. GSTM1 (del.)/CYP2A6 (variant) genotype was associated with a higher risk of NSCLC (OR:12.5, p <0.001). GSTM1 (del.)/CYP2A6 (Ser/Pro+Pro/Pro) and GSTM1 (del.)/CYP2A13 (CT+TT) interacted redundantly (OR_intraction = 0.66 and 0.64). A co-suppressive interaction was observed between GSTT1 (del.)/CYP2A6 (Ser/Pro+Pro/Pro) (OR_intraction = 0.41). Simultaneously, both GSTT1/GSTM1 del. genotype was associated with a significantly higher risk to NSCLC. In contrast, GSTT1 del./GSTM1 del. genotype interaction displayed a co-suppressive effect (OR_intraction = 0.15). CYP1A1(TC+CC)/CYP2A13(CT+TT)mutually interacted synergistically (OR_intraction = 1.27).CYP1A1 (TC+CC)/GSTP1 (Val/Val+Ile/Val) genotype demonstrated an additive (OR_intraction = 1) effect. GSTP1(Val/Val+Ile/Val) interacts with GSTT1 (del.) genotype exerted a suppressive effect (OR_intraction = 0.69). CYP2A6 in smokers increased risk by 4.2 (p = 0.001) to 5.6 fold (p <0.001), while GSTM1 and GSTT1 were independent of smoking.

CONCLUSION

Epistatic interactions revealed that CYPs/GSTs might follow a web of the interactions to modify the risk of NSCLC.

Deciphering the effects of PYCR1 on cell function and its associated mechanism in hepatocellular carcinoma

Overexpression of pyrroline-5-carboxylate reductase 1 (PYCR1) has been associated with the development of certain cancers; however, no studies have specifically examined the role of PYCR1 in hepatocellular carcinoma (HCC). Based on The Cancer Genome Atlas expression array and meta-analysis conducted using the Gene Expression Omnibus database, we determined that PYCR1 was upregulated in HCC compared to adjacent nontumor tissues (P < 0.05). These data were verified using quantitative real-time polymerase chain reaction, western blotting, and immunohistochemistry analysis. Additionally, patients with low PYCR1 expression showed a higher overall survival rate than patients with high PYCR1 expression. Furthermore, PYCR1 overexpression was associated with the female sex, higher levels of alpha-fetoprotein, advanced clinical stages (III and IV), and a younger age (< 45 years old). Silencing of PYCR1 inhibited cell proliferation, invasive migration, epithelial-mesenchymal transition, and metastatic properties in HCC in vitro and in vivo. Using RNA sequencing and bioinformatics tools for data-dependent network analysis, we found binary relationships among PYCR1 and its interacting proteins in defined pathway modules. These findings indicated that PYCR1 played a multifunctional role in coordinating a variety of biological pathways involved in cell communication, cell proliferation and growth, cell migration, a mitogen-activated protein kinase cascade, ion binding, etc. The structural characteristics of key pathway components and PYCR1-interacting proteins were evaluated by molecular docking, and hotspot analysis showed that better affinities between PYCR1 and its interacting molecules were associated with the presence of arginine in the binding site. Finally, a candidate regulatory microRNA, miR-2355-5p, for PYCR1 mRNA was discovered in HCC. Overall, our study suggests that PYCR1 plays a vital role in HCC pathogenesis and may potentially serve as a molecular target for HCC treatment.

The PARP Enzyme Family and the Hallmarks of Cancer Part 2: Hallmarks Related to Cancer Host Interactions

Poly (ADP-ribose) polymerases (PARPs) modify target proteins with a single ADP-ribose unit or with a poly (ADP-ribose) (PAR) polymer. PARP inhibitors (PARPis) recently became clinically available for the treatment of BRCA1/2 deficient tumors via the synthetic lethality paradigm. This personalized treatment primarily targets DNA damage-responsive PARPs (PARP1-3). However, the biological roles of PARP family member enzymes are broad; therefore, the effects of PARPis should be viewed in a much wider context, which includes complex effects on all known hallmarks of cancer. In the companion paper (part 1) to this review, we presented the fundamental roles of PARPs in intrinsic cancer cell hallmarks, such as uncontrolled proliferation, evasion of growth suppressors, cell death resistance, genome instability, replicative immortality, and reprogrammed metabolism. In the second part of this review, we present evidence linking PARPs to cancer-associated inflammation, anti-cancer immune response, invasion, and metastasis. A comprehensive overview of the roles of PARPs can facilitate the identification of novel cancer treatment opportunities and barriers limiting the efficacy of PARPi compounds.

Tamoxifen Downregulates the Expression of Notch1 and DLL1 Genes in MKN-45 Gastric Cancer Cells

PURPOSE

Gastric cancer is one of the most prevalent cancers worldwide and the second most common cause for cancer associated mortality. Anti-tumor effects of tamoxifen in breast cancer are well-established. However, no study has so far investigated the effects of tamoxifen on gene expression of Notch1 and DLL1 in gastric cancer cell line. The present study was conducted to explore the effects of tamoxifen, as a repurposed drug, on gene expression of Notch1 and DLL1 in MKN-45, a gastric cancer cell line.

METHODS

MKN-45 cells were cultured in DMEM/F12 medium containing 10% FBS. Cytotoxic effects of tamoxifen on these cells at various concentrations were evaluated by trypan blue exclusion assay. For gene expression analysis, the cells were first incubated with 100 μM tamoxifen followed by total RNA extraction from treated and control cells. Then, cDNA was synthesized. Quantitative real-time PCR using specific primers for Notch1 and DLL1 was performed to assess the effect of tamoxifen on the transcript of them.

RESULTS

Treatment with tamoxifen decreased viability of MKN-45 cells in a dose-dependent manner. CC₅₀ was estimated to be around 200 μM. Also, tamoxifen at the dose of 100 μM could significantly downregulate mRNA levels of both Notch1 and DLL1 genes as compared with untreated cells by 24% and 92%, respectively.

CONCLUSION

Based on these results, tamoxifen interferes with Notch signaling pathway through downregulating the expression of Notch1 and DLL1 genes and this could be regarded as a mechanism for its anti-cancer effects in this malignant disease.

Detection of epistasis between ACTN3 and SNAP-25 with an insight towards gymnastic aptitude identification

In this study, we performed an analysis of the impact of performance enhancing polymorphisms (PEPs) on gymnastic aptitude while considering epistatic effects. Seven PEPs (rs1815739, rs8192678, rs4253778, rs6265, rs5443, rs1076560, rs362584) were considered in a case (gymnasts)-control (sedentary individuals) setting. The study sample comprised of two athletes' sets: 27 elite (aged 24.8 ± 2.1 years) and 46 sub-elite (aged 19.7 ± 2.4 years) sportsmen as well as a control group of 245 sedentary individuals (aged 22.5 ± 2.1 years). The DNA was derived from saliva and PEP alleles were determined by PCR, RT-PCR. Following Multifactor Dimensionality Reduction, logistic regression models were built. The synergistic effect for rs1815739 x rs362584 reached 5.43%. The rs1815739 x rs362584 epistatic regression model exhibited a good fit to the data (Chi-squared = 33.758, p ≈ 0) achieving a significant improvement in sportsmen identification over naïve guessing. The area under the receiver operating characteristic curve was 0.715 (Z-score = 38.917, p ≈ 0). In contrast, the additive ACTN3 -SNAP-25 logistic regression model has been verified as non-significant. We demonstrate that a gene involved in the differentiation of muscle architecture-ACTN3 and a gene, which plays an important role in the nervous system-SNAP-25 interact. From the perspective originally established by the Berlin Academy of Science in 1751, the matter of communication between the brain and muscles via nerves adopts molecular manifestations. Further in-vitro investigations are required to explain the molecular details of the rs1815739 -rs362584 interaction.

Synergistic activation of NF-κB by TNFAIP3 (A20) reduction and UBE2L3 (UBCH7) augment that synergistically elevate lupus risk

Background

Systemic lupus erythematosus (SLE) is an autoimmune inflammatory rheumatic disease. SLE susceptibility is affected by multiple genetic elements, environmental factors, and their interactions. We aimed in this study to statistically and functionally characterize a gene-gene interaction (epistasis) recently documented to affect SLE risk.

Methods

Two single-nucleotide polymorphisms, rs2230926 in TNFAIP3 (A20) gene and rs131654 in UBE2L3 (UBCH7) gene, were genotyped in all 3525 Korean participants, and their SLE risk association and epistasis were statistically analyzed by calculating odds ratio (OR), 95% confidence interval (CI), and P values in genotype comparisons between 1318 SLE patients and 2207 healthy controls. Furthermore, their effects on gene functions were assessed by comparatively examining separate and combined effects of TNFAIP3 and UBE2L3 knockdowns on NF-κB transcription factor activity in human cells.

Results

SLE susceptibility is associated with TNFAIP3 rs2230926 (OR = 1.9, 95% CI 1.6–2.4, P = 8.6 × 10⁻¹¹) and UBE2L3 rs131654 (OR = 1.2, 95% CI 1.1–1.4, P = 1.1 × 10⁻⁴) in a Korean population of this study. Their risk-associated alleles synergistically elevate SLE susceptibility in both multivariate logistic regression analysis (OR_interaction = 1.6, P = 0.0028) and genotype-stratified analysis (OR_interaction = 2.4), confirming the synergistic TNFAIP3-UBE2L3 interaction in SLE risk. Additionally, the SLE-susceptible alleles confer decreased TNFAIP3 expression (P = 1.1 × 10⁻⁶, n = 610) and increased UBE2L3 expression (P = 9.5 × 10⁻¹¹, n = 475), respectively, in B cell analysis of the International HapMap Project individuals with adjustment for ethnicity. Furthermore, when compared with TNFAIP3 non-knockdown and UBE2L3 knockdown in human HeLa cells, TNFAIP3 knockdown and UBE2L3 non-knockdown synergistically increase three cytokines, CCL2, CXCL8 (IL8), and IL6, all regulated by NF-κB in the human TNFR signaling pathway.

Conclusions

A synergistic interaction between TNFAIP3 and UBE2L3 genes is observed in SLE risk, as being evident in comparison of genotype distributions between SLE patients and controls. Additionally, the synergistic gene-gene interaction is functionally validated, as TNFAIP3 reduction and UBE2L3 augment exert synergism in activation of NF-κB and subsequent induction of inflammatory cytokines. Accordingly, SLE inflammation and risk could be synergistically alleviated by TNFAIP3 upregulation and UBE2L3 downregulation.

Synergistic triad epistasis of epigenetic H3K27me modifier genes, EZH2, KDM6A, and KDM6B, in gastric cancer susceptibility

BACKGROUND

For an epigenetic regulation of human genome, three enzymes write or erase methylation of lysine-27 residue on histone H3 (H3K27me). This methylation is catalyzed by EZH2 (KMT6A) methyltransferase and reversed by KDM6A (UTX) or KDM6B (JMJD3) demethylase. Genetic cancer risk association has been reported on EZH2, but not on KDM6A or KDM6B yet.

METHODS

A total of 23 tag single-nucleotide polymorphisms (SNPs) of the three genes were genotyped in 2349 Korean participants, and their gastric cancer risk associations and epistases were statistically examined by comparing the SNP genotypes of 1100 gastric cancer patients and 1249 healthy controls.

RESULTS

All three genes are individually associated with gastric cancer susceptibility, as evident with the genotypes of KDM6A SNP rs5952279 (P = 0.00010) and rs144974719 (P = 0.00024), KDM6B rs78633955 (P = 0.0019) and rs11657063 (P = 0.0036), and EZH2 rs67648693 (P = 0.0028) and rs1061037 (P = 0.023). Furthermore, when odds ratio of interaction (OR_int) is calculated for all intergenic SNP pairs, synergistic epistasis is evident among the three genes. Specifically, the interaction is synergistic between EZH2 rs58579167 and KDM6A rs5952279 (OR_int = 3.2, P = 0.00066), between KDM6A rs2230018 and KDM6B rs78633955 (OR_int = 1.9, P = 0.044), and between KDM6B rs78633955 and EZH2 rs73158295 (OR_int = 1.7, P = 0.00030). These inter-SNP interactions together constitute a synergistic triad epistasis of ring-type topology.

CONCLUSIONS

All three H3K27me modifier genes are individually associated with gastric cancer susceptibility with synergistic triad interaction. Not only two enzymes with the same function (KDM6A and KDM6B), but also those with opposite functions (EZH2 versus KDM6A or KDM6B) synergistically affect H3K27me consequences such as gastric cancer susceptibility.

Drug resistance: origins, evolution and characterization of genomic clones and the tumor ecosystem to optimize precise individualized therapy

Progress in understanding and overcoming fatal intrinsic and acquired resistance is slow, with only a few exceptions. Despite advances in modern genome and transcriptome analysis, the controversy of the three different theories on drug resistance and tumor progression, namely dynamic intratumor heterogeneity, pre-existing minor genomic clones and tumor ecosystem, is unresolved. Moreover, evidence on transcriptional heterogeneity suggests the necessity of a drug bank for individualized, precise drug-sensitivity prediction. We propose a cancer type- and stage-specific clinicogenomic and tumor ecosystemic concept toward cancer precision medicine, focusing on early therapeutic resistance and relapse.

Transcriptome‑wide piRNA profiling in human gastric cancer

Piwi-interacting RNAs (piRNAs) comprise the largest class of non-coding RNAs. They represent a molecular feature shared by all non-aging biological systems, including germline and somatic cancer stem cells, which display an indefinite capacity of renewal and proliferation and are potentially immortal. They have been identified in animal stomachs, but their relationship with human gastric cancers remains largely unclear. The present study aimed to identify the piRNAs associated with human gastric cancers across the whole transcriptome. Fresh tumor tissues and adjacent non-tumorous tissues from stomachs were examined using a piRNA microarray (23,677 piRNAs) that was then validated by qPCR. The differential expression of piRNAs between cases and controls was analyzed. The transposable elements (TEs) that are potentially targeted by the risk piRNAs were searched. The expression of the nearest genes that are complementary to the sequences of the piRNAs was examined in the stomach tissue. The regulatory effects of genome-wide significant and replicated cancer-risk DNA variants on the piRNA expression in stomach were tested. Based on the findings, we identified a total of 8,759 piRNAs in human stomachs. Of all, 50 were significantly (P<0.05) and differentially (>2-fold change) expressed between the cases and controls, and 64.7% of the protein-coding genes potentially regulated by the gastric cancer-associated piRNAs were expressed in the human stomach. The expression of many cancer-associated piRNAs was correlated with the genome-wide and replicated cancer-risk SNPs. In conclusion, we conclude that piRNAs are abundant in human stomachs and may play important roles in the etiological processes of gastric cancers.

Involvement of N-glycan in Multiple Receptor Tyrosine Kinases Targeted by Ling-Zhi-8 for Suppressing HCC413 Tumor Progression

The poor prognosis of hepatocellular carcinoma (HCC) is resulted from tumor metastasis. Signaling pathways triggered by deregulated receptor tyrosine kinases (RTKs) were the promising therapeutic targets for prevention of HCC progression. However, RTK-based target therapy using conventional kinase-based inhibitors was often hampered by resistances due to compensatory RTKs signaling. Herein, we report that Ling-Zhi-8 (LZ-8), a medicinal peptide from Ganoderma lucidium, was effective in suppressing cell migration of HCC413, by decreasing the amount and activity of various RTKs. These led to the suppression of downstream signaling including phosphorylated JNK, ERK involved in HCC progression. The capability of LZ-8 in targeting multiple RTKs was ascribed to its simultaneous binding to these RTKs. LZ-8 may bind on the N-linked glycan motif of RTKs that is required for their maturation and function. Notably, pretreatment of the N-glycan trimming enzyme PNGase or inhibitors of the mannosidase (N-glycosylation processing enzyme), kifunensine (KIF) and swainsonine (SWN), prevented LZ-8 binding on the aforementioned RTKs and rescued the downstream signaling and cell migration suppressed by LZ-8. Moreover, pretreatment of KIF prevented LZ-8 triggered suppression of tumor growth of HCC413. Our study suggested that a specific type of N-glycan is the potential target for LZ-8 to bind on multiple RTKs for suppressing HCC progression.

PARI functions as a new transcriptional target of FOXM1 involved in gastric cancer development

PARI, an element of the homologous recombination pathway of DNA repair,is involved in the regulation of cell cycle and carcinogenesis in pancreatic cancer. However, little is known about the function and regulatory mechanism of PARI in other cancers. In the present study, we evaluated the expression of PARI in gastric cancer (GC) by immunohistochemical analysis in a tissue microarray and characterized its functions using in vitro assays and in vivo animal models. We found higher expression of PARI protein was shown in GC tissues compared with related adjacent normal gastric mucosa tissues. Knockdown of PARI by RNA inference decreased cell proliferation, migration, and invasion of GC cells in vitro, as well as reduced the xenograft tumor growth and lung metastasis formation in vivo. Quantitative real-time PCR and western blot results revealed that PARI expression was activated by a well-known oncogene FOXM1 and positively correlated with FOXM1 expression at mRNA level in 38 paired of GC samples. Luciferase reporter assay and chromatin immunoprecipitation assay further demonstrated that FOXM1 directly regulated PARI transcription by binding to the specific sequences of PARI promoter. In addition, PARI knockdown blocked the effect of FOXM1 on GC cell migration. Taken together, our results suggest that PARI plays potential oncogenic roles and functions as a transcriptional target and effector of FOXM1 in GC development.

PARP-1 serves as a novel molecular marker for hepatocellular carcinoma in a Southern Chinese Zhuang population

PARP-1 (poly(ADP-ribose) polymerase-1) plays an important role in tumorigenesis. Since its effects on different populations are varied, this study investigated the impact of PARP-1 on primary hepatocellular carcinoma in a Southern Chinese Zhuang population. We assessed the global PARP-1 messenger RNA expression in patients with hepatocellular carcinoma using The Cancer Genome Atlas dataset. Increased PARP-1 expression, related to alpha-fetoprotein level, was observed. The area under the receiver operating characteristic curve value was 0.833. Kaplan-Meier survival curves indicated that higher PARP-1 expression was not correlated with poorer overall survival and recurrence-free survival. In a Zhuang population, PARP-1 messenger RNA and protein levels were increased in the hepatocellular carcinoma tissue and its adjacent liver tissues as assessed by quantitative polymerase chain reaction, immunohistochemistry, and western blotting. Higher PARP-1 level was associated with a higher tumor stage (p < 0.05), without correlation with age, gender, smoking, drinking, tumor size, serum alpha-fetoprotein level, hepatitis B virus infection, metastasis, and invasion (p > 0.05). Further analysis suggested that H2AX, a PARP-1 protein interaction partner, was coordinated with PARP-1 in hepatocellular carcinoma tumorigenesis. Overall, some new characteristics of PARP-1 expression were noted in the Zhuang population. PARP-1 is a novel promising diagnostic marker for hepatocellular carcinoma in the Southern Chinese Zhuang population.

SPP1, analyzed by bioinformatics methods, promotes the metastasis in colorectal cancer by activating EMT pathway

OBJECTIVE

Tumor metastasis is still a great challenge for the prognosis of colorectal cancer (CRC). Although secreted phosphoprotein 1 (SPP1) over-expression is confirmed to associate with invasion, metastasis of CRC, the underlying mechanism by which modulates the CRC metastasis is still not fully explained.

METHOD

GDS4382 was obtained from GEO database and differentially expressed genes (DEGs) were analyzed by bioinformatics methods 55 paired samples of CRC and adjacent non-cancerous tissues were collected to detect the expression of SPP1 by q-PCR and western blot. Functional analysis of siRNA-SPP1, including proliferation, apoptosis, colony formation, cell cycle, migration, was investigated in CRC cell lines and tumor xenografts were conducted in nude mice. Protein expression of E-cadherin and vimentin was detected by western blot.

RESULTS

1887 DEGs were analyzed and selected from GDS4382, of which, SPP1 and epithelial-mesenchymal-transition (EMT) showed a close association by bioinformatics analysis. The mRNA and protein expression of SPP1 were significantly higher in CRC tissues than that in adjacent non-cancerous tissues (P<0.05). Overexpression of SPP1 closely associated with tumor invasion, metastasis and low survival in CRC. Moreover, siRNA-SPP1 repressed proliferation, cell cycle, colony formation, migration and tumor growth in vivo and promoted cell apoptosis in CRC cell lines. In addition, Protein expression of E-cadherin was obviously up-regulated and Vimentin was down-regulated in CRC cells after siRNA-SPP1 (P<0.05).

CONCLUSION

SPP1 expression was significantly up-regulated in CRC. And SPP1 promoted the metastasis of CRC by activating EMT, which could be a potentially therapeutic target for patients with CRC.

Gastric cancer: Metabolic and metabolomics perspectives (Review)

Gastric cancer is one of the most malignant tumors worldwide and remains a major health threat in Asia-Pacific regions, while its pathological mechanism is generally unknown. Recent research has advanced the understanding of the relationship between metabolic reprogramming and carcinogenesis. In particular, metabolic regulation and cancer research are being further brought into sharp focus with the emergence of metabolomics. Not only can metabolomics provide global information on metabolic profiles of specific tumors, but it can also act as a promising tool to discover biomarkers regarding diagnosis, metastatic surveillance and chemotherapeutic sensitivity prediction. Meanwhile, metabolism-based anticancer therapies will be further discovered. Up to now, accumulative studies have highlighted the application of metabolomics in gastric cancer research regarding different aspects; therefore we summarized the current available results of how metabolic changes are linked to gastric carcinogenesis, and how metabolomics holds promise for the diagnosis, metastatic surveillance, treatment and prognosis prediction of gastric cancer.