PLA2 (group IIA phospholipase A2) as a prognostic determinant in stage II colorectal carcinoma

Correlation analysis between immune-related genes and cell infiltration revealed prostate cancer immunotherapy biomarkers linked to T cells gamma delta

Prostate cancer (PCa) is a urological malignancy with poor prognosis. Immune-related genes are associated with immune infiltration in prostate cancer, but their role in immunogenic PCa is less well understood. We assessed the infiltration patterns of 22 immune cells in PCa and the relationship of immune-related differentially expressed genes (IDEGs) with them. The 87 IDEGs are involved in the interaction between the extracellular matrix and the tumor microenvironment. The model, including seven IDEGs (SLPI, DES, IAPP, NPY, ISG15, PLA2G2A, and HLA-DMB), showed a good predictive power. The SLPI expression is positively correlated with the infiltration level of T cells gamma delta. In addition, PCa has high infiltration levels in Macrophages M1 (18.07%) and Dendritic cells activated (17.64%). The correlation analysis between IDEGs and immune cell infiltration suggested that PCa immunotherapy biomarkers may be closely related to T cells gamma delta.

The Role of Inflammatory Mediators in Colorectal Cancer Hepatic Metastasis

Colorectal cancer (CRC) is the second leading cause of death in cancer patients in the USA, whereas the major cause of CRC deaths is hepatic metastases. The liver is the most common site of metastasis in patients with CRC due to hepatic portal veins receiving blood from the digestive tract. Understanding the cellular and molecular mechanisms of hepatic metastases is of dire need for the development of potent targeted therapeutics. Immuno-signaling molecules including cytokines and chemokines play a pivotal role in hepatic metastases from CRC. This brief review discusses the involvement of three representative cytokines (TNF-α, IL-6 and IL-1β), a lipid molecule PGE2 and two chemokines (CXCL1 and CXCL2) in the process of CRC liver metastases.

Phospholipase A2, a nonnegligible enzyme superfamily in gastrointestinal diseases

Gastrointestinal tract is important for digestion, absorption, detoxification and immunity. Gastrointestinal diseases are mainly caused by the imbalance of protective and attacking factors in gastrointestinal mucosa, which can seriously harm human health. Phospholipase A₂ (PLA₂) is a large family closely involved in lipid metabolism and is found in almost all human cells. A growing number of studies have revealed that its metabolites are deeply implicated in various inflammatory pathways and also regulates the maintenance of numerous biological events such as dietary digestion, membrane remodeling, barrier action, and host immunity. In addition to their phospholipase activity, some members of the superfamily also have other catalytic activities. Based on the in-depth effects of phospholipase A2 on bioactive lipid metabolism and inflammatory cytokines, PLA₂ and its metabolites are likely to be involved in the pathogenesis, development or prevention of gastrointestinal diseases. Therefore, this review will focus on the physiological and pathogenic roles of several important PLA₂ enzymes in the gastrointestinal tract, and reveals the potential of PLA₂ as a therapeutic target for gastrointestinal diseases.

Lipid metabolism in cancer progression and therapeutic strategies

Dysregulated lipid metabolism represents an important metabolic alteration in cancer. Fatty acids, cholesterol, and phospholipid are the three most prevalent lipids that act as energy producers, signaling molecules, and source material for the biogenesis of cell membranes. The enhanced synthesis, storage, and uptake of lipids contribute to cancer progression. The rewiring of lipid metabolism in cancer has been linked to the activation of oncogenic signaling pathways and cross talk with the tumor microenvironment. The resulting activity favors the survival and proliferation of tumor cells in the harsh conditions within the tumor. Lipid metabolism also plays a vital role in tumor immunogenicity via effects on the function of the noncancer cells within the tumor microenvironment, especially immune‐associated cells. Targeting altered lipid metabolism pathways has shown potential as a promising anticancer therapy. Here, we review recent evidence implicating the contribution of lipid metabolic reprogramming in cancer to cancer progression, and discuss the molecular mechanisms underlying lipid metabolism rewiring in cancer, and potential therapeutic strategies directed toward lipid metabolism in cancer. This review sheds new light to fully understanding of the role of lipid metabolic reprogramming in the context of cancer and provides valuable clues on therapeutic strategies targeting lipid metabolism in cancer.

Single-cell analysis reveals the pan-cancer invasiveness-associated transition of adipose-derived stromal cells into COL11A1-expressing cancer-associated fibroblasts

During the last ten years, many research results have been referring to a particular type of cancer-associated fibroblasts associated with poor prognosis, invasiveness, metastasis and resistance to therapy in multiple cancer types, characterized by a gene expression signature with prominent presence of genes COL11A1, THBS2 and INHBA. Identifying the underlying biological mechanisms responsible for their creation may facilitate the discovery of targets for potential pan-cancer therapeutics. Using a novel computational approach for single-cell gene expression data analysis identifying the dominant cell populations in a sequence of samples from patients at various stages, we conclude that these fibroblasts are produced by a pan-cancer cellular transition originating from a particular type of adipose-derived stromal cells naturally present in the stromal vascular fraction of normal adipose tissue, having a characteristic gene expression signature. Focusing on a rich pancreatic cancer dataset, we provide a detailed description of the continuous modification of the gene expression profiles of cells as they transition from APOD-expressing adipose-derived stromal cells to COL11A1-expressing cancer-associated fibroblasts, identifying the key genes that participate in this transition. These results also provide an explanation to the well-known fact that the adipose microenvironment contributes to cancer progression.

Transcriptome-wide profiles of circular RNA and RNA-binding protein interactions reveal effects on circular RNA biogenesis and cancer pathway expression

Background

Circular RNAs (circRNAs) are stable, often highly expressed RNA transcripts with potential to modulate other regulatory RNAs. A few circRNAs have been shown to bind RNA-binding proteins (RBPs); however, little is known about the prevalence and distribution of these interactions in different biological contexts.

Methods

We conduct an extensive screen of circRNA-RBP interactions in the ENCODE cell lines HepG2 and K562. We profile circRNAs in deep-sequenced total RNA samples and analyze circRNA-RBP interactions using a large set of eCLIP data with binding sites of 150 RBPs. We validate interactions for select circRNAs and RBPs by performing RNA immunoprecipitation and functionally characterize our most interesting candidates by conducting knockdown studies followed by RNA-Seq.

Results

We generate a comprehensive catalog of circRNA-RBP interactions in HepG2 and K562 cells. We show that KHSRP binding sites are enriched in flanking introns of circRNAs and that KHSRP depletion affects circRNA biogenesis. We identify circRNAs that are highly covered by RBP binding sites and experimentally validate individual circRNA-RBP interactions. We show that circCDYL, a highly expressed circRNA with clinical and functional implications in bladder cancer, is almost completely covered with GRWD1 binding sites in HepG2 cells, and that circCDYL depletion counteracts the effect of GRWD1 depletion. Furthermore, we confirm interactions between circCDYL and RBPs in bladder cancer cells and demonstrate that circCDYL depletion affects hallmarks of cancer and perturbs the expression of key cancer genes, e.g., TP53. Finally, we show that elevated levels of circCDYL are associated with overall survival of bladder cancer patients.

Conclusions

Our study demonstrates transcriptome-wide and cell-type-specific circRNA-RBP interactions that could play important regulatory roles in tumorigenesis.

Survival prediction in patients with colon adenocarcinoma via multi-omics data integration using a deep learning algorithm

This study proposed a deep learning (DL) algorithm to predict survival in patients with colon adenocarcinoma (COAD) based on multi-omics integration. The survival-sensitive model was constructed using an autoencoder for DL implementation based on The Cancer Genome Atlas (TCGA) data of patients with COAD. The autoencoder framework was compared to PCA, NMF, t-SNE, and univariable Cox-PH model for identifying survival-related features. The prognostic robustness of the inferred survival risk groups was validated using three independent confirmation cohorts. Differential expression analysis, Pearson's correlation analysis, construction of miRNA-target gene network, and function enrichment analysis were performed. Two risk groups with significant survival differences were identified in TCGA set using the autoencoder-based model (log-rank p-value = 5.51e-07). The autoencoder framework showed superior performance compared to PCA, NMF, t-SNE, and the univariable Cox-PH model based on the C-index, log-rank p-value, and Brier score. The robustness of the classification model was successfully verified in three independent validation sets. There were 1271 differentially expressed genes, 10 differentially expressed miRNAs, and 12 hypermethylated genes between the survival risk groups. Among these, miR-133b and its target genes (GNB4, PTPRZ1, RUNX1T1, EPHA7, GPM6A, BICC1, and ADAMTS5) were used to construct a network. These genes were significantly enriched in ECM-receptor interaction, focal adhesion, PI3K-Akt signaling pathway, and glucose metabolism-related pathways. The risk subgroups obtained through a multi-omics data integration pipeline using the DL algorithm had good robustness. miR-133b and its target genes could be potential diagnostic markers. The results would assist in elucidating the possible pathogenesis of COAD.

Phospholipase A2 superfamily in cancer

Phospholipase A2 enzymes (PLA₂s) comprise a superfamily that is generally divided into six subfamilies known as cytosolic PLA₂s (cPLA₂s), calcium-independent PLA₂s (iPLA₂s), secreted PLA₂s (sPLA₂s), lysosomal PLA₂s, platelet-activating factor (PAF) acetylhydrolases, and adipose specific PLA₂s. Each subfamily consists of several isozymes that possess PLA₂ activity. The first three PLA₂ subfamilies play important roles in inflammation-related diseases and cancer. In this review, the roles of well-studied enzymes sPLA₂-IIA, cPLA₂α and iPLA₂β in carcinogenesis and cancer development were discussed. sPLA₂-IIA seems to play conflicting roles and can act as a tumor suppressor or a tumor promoter according to the cancer type, but cPLA₂α and iPLA₂β play protumorigenic role in most cancers. The mechanisms of PLA₂-mediated signal transduction and crosstalk between cancer cells and endothelial cells in the tumor microenvironment are described. Moreover, the mechanisms by which PLA₂s mediate lipid reprogramming and glycerophospholipid remodeling in cancer cells are illustrated. PLA₂s as the upstream regulators of the arachidonic acid cascade are generally high expressed and activated in various cancers. Therefore, they can be considered as potential pharmacological targets and biomarkers in cancer. The detailed information summarized in this review may aid in understanding the roles of PLA₂s in cancer, and provide new clues for the development of novel agents and strategies for tumor prevention and treatment.

Focus on the glycerophosphocholine pathway in choline phospholipid metabolism of cancer

Activated choline metabolism is a hallmark of carcinogenesis and tumor progression, which leads to elevated levels of phosphocholine and glycerophosphocholine in all types of cancer tested so far. Magnetic resonance spectroscopy applications have played a key role in detecting these elevated choline phospholipid metabolites. To date, the majority of cancer-related studies have focused on phosphocholine and the Kennedy pathway, which constitutes the biosynthesis pathway for membrane phosphatidylcholine. Fewer and more recent studies have reported on the importance of glycerophosphocholine in cancer. In this review article, we summarize the recent literature on glycerophosphocholine metabolism with respect to its cancer biology and its detection by magnetic resonance spectroscopy applications.

Prognostic value of Osteopontin (SPP1) in colorectal carcinoma requires a personalized molecular approach

Stratification of colorectal cancer for better management and tangible clinical outcomes is lacking in clinical practice. To reach this goal, the identification of reliable biomarker(s) is a prerequisite to deliver personalized colorectal cancer theranostics. Osteopontin (SPP1) is a key extracellular matrix protein involved in several pathophysiological processes including cancer progression and metastasis. However, the exact molecular mechanisms regulating its expression, localization, and molecular functions in cancer are still poorly understood. This study was designed to investigate the SPP1 expression profiles in Saudi colorectal cancer patients, and to assess its prognostic value. Hundred thirty-four (134) archival paraffin blocks of colorectal cancer were collected from King Abdulaziz University Hospital, Saudi Arabia. Tissue microarrays were constructed, and automated immunohistochemistry was performed to evaluate SPP1 protein expression patterns in colorectal cancer. About 20% and 23% of our colorectal cancer samples showed high SPP1 cytoplasmic and nuclear expression patterns, respectively. Cytoplasmic SPP1 did not correlate with age, gender, tumor size, and location. However, significant correlations were observed with tumor grade (p = 0.008), tumor invasion (p = 0.01), and distant metastasis (p = 0.04). Kaplan-Meier survival analysis showed a significantly lower recurrence rate in patients with higher SPP1 cytoplasmic expression (p = 0.05). At multivariate analysis, high SPP1 cytoplasmic expression was an independent favorable prognostic marker (p = 0.02). However, nuclear SPP1 expression did not show any prognostic value (p = 0.712). Our results showed a particular SPP1 prognostic relevance that is not in line with most colorectal cancer previous studies that may be attributed to the molecular pathophysiology of our colorectal cancer cohort. Saudi Arabia has both specific genomic makeup and particular environment that could lead to distinctive molecular roots of cancer. SPP1 has several isoforms, tissue localizations and molecular functions, signaling pathways, and downstream molecular functions. Therefore, a more individualized approach for CRC studies and particularly SPP1 prognosis outcomes' assessment is highly recommended toward precision oncology.

Membranous or Cytoplasmic HER2 Expression in Colorectal Carcinoma: Evaluation of Prognostic Value Using Both IHC & BDISH

BACKGROUND

Human epidermal growth factor recptor-2 (HER2) was identified as a driver gene in several types of cancers with both prognostic and predictive value. However, the molecular association of HER2 gene mutation with HER2 gene amplification and/or protein expression in cancer tissues has not been clearly defined. Moreover, there is little information available on HER2 status role in tumor progression and metastasis in colorectal carcinoma (CRC) compared to other solid tumors. The aim of this study was to evaluate both HER2 amplification and protein expression profiles using immunohistochemistry (IHC) and bright-field dual in situ hybridization (BDISH) techniques, respectively.

PATIENTS AND METHODS

Tissue microarray (TMA) was constructed to accommodate a total of 243 CRC formalin-fixed paraffin embedded (FFPE) samples of consent patients and stained by IHC and BDISH methods. The expression patterns of HER2 protein status were evaluated and correlated to HER2 gene amplification status and then assessed for its prognostic value.

RESULTS

The expression profile of 58% samples showed cytoplasmic expression patterns of different categories. Interestingly, only 1% showed strong (+3) membranous expression pattern of HER2 with perfect match with their corresponding gene amplification status (>2). However, the cytoplasmic HER2 protein status did not show significant correlation with most clinicopathological features and survival outcomes except with age (p = 0.04) and tumor size (p = 0.03).

CONCLUSION

We demonstrated that the membranous HER2 gene/protein status is infrequent, while the main fraction of HER2 overexpression was cytoplasmic and lacking prognostic value. This cytoplasmic HER2 overexpression was induced through a gene-amplification independent pathway, making the HER2 gene status evaluation approach in those cases not worthy. Further investigations about the molecular pathways of the cytoplasmic HER2 protein in CRC and its associations with survival outcomes are required to allow either a breakthrough in CRC management; or to confirm the hypothesis of a marginal role in CRC onset and progression.

Plasma phospholipase A2 activity may serve as a novel diagnostic biomarker for the diagnosis of breast cancer

Previous studies have indicated that phospholipase A2 (PLA2) may be associated with tumorigenesis in human tissues. The present study aimed to investigate the association between plasma PLA2 activity and the breast cancer (BC) status of patients. Increased plasma PLA2 activity was detected in patients with breast cancer when compared with healthy controls. Plasma samples were obtained from patients with BC (n=169), patients with benign disease (BD; n=80) and healthy controls (n=81). PLA2 activity was assessed using a quantitative fluorescent assay with selective inhibitors. It was demonstrated that increased PLA2 and secretory PLA2 (sPLA2) activity was associated with tumor stage, particularly in patients with late-stage disease. Additionally, smoking, alcohol consumption, body mass index (BMI) and age of patients did not have a significant effect on PLA2 activity. Analysis of receiver operating characteristic curves revealed that plasma PLA2 and sPLA2 activities were increased in BC patients compared with healthy controls. It was concluded that plasma PLA2 activity may serve as a biomarker for patients with BC.

Alterations in the epithelial stem cell compartment could contribute to permanent changes in the mucosa of patients with ulcerative colitis

OBJECTIVE

UC is a chronic inflammatory disease of the colonic mucosa. Growing evidence supports a role for epithelial cell defects in driving pathology. Moreover, long-lasting changes in the epithelial barrier have been reported in quiescent UC. Our aim was to investigate whether epithelial cell defects could originate from changes in the epithelial compartment imprinted by the disease.

DESIGN

Epithelial organoid cultures (EpOCs) were expanded ex vivo from the intestinal crypts of non-IBD controls and patients with UC. EpOCs were induced to differentiate (d-EpOCs), and the total RNA was extracted for microarray and quantitative real-time PCR (qPCR) analyses. Whole intestinal samples were used to determine mRNA expression by qPCR, or protein localisation by immunostaining.

RESULTS

EpOCs from patients with UC maintained self-renewal potential and the capability to give rise to differentiated epithelial cell lineages comparable with control EpOCs. Nonetheless, a group of genes was differentially regulated in the EpOCs and d-EpOCs of patients with UC, including genes associated with antimicrobial defence (ie, LYZ, PLA2G2A), with secretory (ie, ZG16, CLCA1) and absorptive (ie, AQP8, MUC12) functions, and with a gastric phenotype (ie, ANXA10, CLDN18 and LYZ). A high rate of concordance was found in the expression profiles of the organoid cultures and whole colonic tissues from patients with UC.

CONCLUSIONS

Permanent changes in the colonic epithelium of patients with UC could be promoted by alterations imprinted in the stem cell compartment. These changes may contribute to perpetuation of the disease.

Promoting effect of hepatitis B virus on the expressoin of phospholipase A2 group IIA

Background

Hepatitis B virus (HBV) infection causes acute and chronic liver disease, ultimately leading to the development of liver cirrhosis (LC) and hepatocellular carcinoma (HCC). Phospholipase A2 group IIA (PLA2G2A) plays important roles in the development and progression of many tumors. Thus far, there have been no reports on the association between HBV and PLA2G2A. The present study investigated the effect of HBV infection on PLA2G2A expression and its application in the diagnosis of HBV-related diseases.

Methods

Serum levels of PLA2G2A in 308 HBV-infected patients and 185 healthy controls were measured using an enzyme-linked immunosorbent assay (ELISA). The difference in serum levels of PLA2G2A was analyzed among chronic hepatitis B (CHB), LC, and HCC patients. PLA2G2A mRNA and protein expression in HepG2 and HepG2.2.15 cells carrying the integrated HBV genome were measured using reverse transcription polymerase chain reaction (RT-PCR) and western blot assays. The HBV infectious clone pHBV1.3, the control plasmid pBlue-ks and PLA2G2A gene promoter were transfected into HepG2 and HepG2.2.15 cells. After transfection, the luciferase activity was measured in the cells. PLA2G2A mRNA and protein expression levels were examined using RT-PCR and western blot assays.

Results

The serum levels of PLA2G2A were 258.3 ± 20.3ng/dl in the healthy controls and 329.0 ± 22.5ng/dl, 385.4 ± 29.3ng/dl and 459.2 ± 38.6ng/dl in the CHB, LC, and HCC patients, respectively. Statistical analyses revealed significantly higher serum levels of PLA2G2A in CHB, LC, and HCC patients than in the healthy controls (P < 0.05), and PLA2G2A levels were elevated in the order of HCC > LC > CHB group. High serum PLA2G2A levels in HCC patients were associated with a lower prevalence of lymph node metastasis and a lower TNM stage. HepG2.2.15 cells carrying the HBV genome expressed higher levels of PLA2G2A mRNA and protein than the HepG2 cells. In addition, HBV triggered PLA2G2A promoter activity and enhanced PLA2G2A mRNA and protein expression compared to the empty vector pBlue-ks.

Conclusion

HBV can upregulate the expression of PLA2G2A, and serum levels of PLA2G2A are associated with the progression of HBV-related diseases.

Overexpression of GRO-β is associated with an unfavorable outcome in colorectal cancer

Growth-related oncogene (GRO)-β, or chemokine (C-X-C motif) ligand 2 (CXCL2), is a member of the CXC chemokine family that may mediate various functions, including attracting neutrophils to sites of inflammation, and participating in tumorigenesis and progression. However, the expression of GRO-β in colorectal cancer (CRC) and the association with the clinical outcome of the disease remains poorly understood. In the present study, CXCL2 mRNA expression in CRC was analyzed using six independent datasets from the Oncomine microarray database. The immunohistochemical analysis of tissue microarrays (TMA) was used to characterize the expression of the GRO-β protein in CRC. The association between GRO-β expression and the clinicopathological features and prognosis of patients was determined by statistical analysis. The results indicated that GRO-β was highly expressed in CRC tissues, and that high GRO-β cytoplasmic expression was associated with the tumor location, extent of the primary tumor, and lymph node metastasis. Kaplan-Meier survival and Cox regression analysis revealed that high GRO-β expression was an independent indicator of poor prognosis for CRC patients. The results indicate that high GRO-β expression in CRC may correlate with an unfavorable outcome and facilitate cancer cell invasion and metastasis.

Prognostic significance of PLA2G4C gene polymorphism in patients with stage II colorectal cancer

BACKGROUND

Phospholipase A2 Group IV C (PLA2G4C) catalyzes the release of certain fatty acids from phospholipids and plays a role in a range of physiological functions, such as remodeling of cell membranes and the production of prostaglandins. Furthermore, it has been proposed that PLA2G4C plays an important role in breast cancer cell chemotaxis. This study aimed to investigate the effect of a single nucleotide polymorphism (SNP) rs1549637 (T>A) of the PLA2G4C gene on the prognosis of colorectal cancer (CRC).

MATERIAL AND METHODS

Whole blood DNA was extracted from 381 patients with CRC and 618 controls, and a TaqMan SNP genotyping assay was used to determine the distribution of the genotypes. Cancer-specific and disease-free survival was analyzed by Kaplan-Meier graphs and by uni- and multivariable Cox regression.

RESULTS

The cancer-specific survival differed between the genotypes (p = 0.019) and the carriers of the A allele were associated with the highest risk of CRC death, with a hazard ratio (HR) of 1.72 [95% confidence interval (CI) 1.17-2.53, p = 0.006] compared with homozygous carriers of the T allele. This increased mortality in the carriers with the allele A was especially marked in stage II with an HR of 3.84 (95% CI 1.51-9.78, p = 0.005).

CONCLUSION

The A allele in PLA2G4C SNP (rs1549637) is associated with a worse prognosis in patients with CRC, especially in stage II disease, and it could be a potential prognostic biomarker in the planning of individual adjuvant therapy in stage II patients.

Immunohistochemical Analysis of Expressions of RB1, CDK4, HSP90, cPLA2G4A, and CHMP2B Is Helpful in Distinction between Myxofibrosarcoma and Myxoid Liposarcoma

The role and diagnostic efficacy of gene and protein products RB1, CDK4, CHMP2B, HSP90, and cPLA2G4A, all previously shown to be involved in tumor genesis and cell proliferation, were examined by immunohistochemical techniques in 32 cases of myxofibrosarcomas and 29 myxoid liposarcomas (all diagnosis had been confirmed by fluorescence in situ hybridization). HSP90 demonstrated strong nuclear and cytoplasmic positivity in all myxoid liposarcoma cases, while only 4 myxofibrosarcomas showed scattered HSP90 positivity. All but 4 cases of myxofibrosarcoma displayed strong positivity for cPLA2G4A, while only 2 myxoid liposarcoma cases were cPLA2G4A positive and both were CHMP2B negative. Overexpression of both cPLA2G4A and CHMP2B also suggested higher tumor grade. In conclusion, HSP90 and cPLA2G4A immunohistochemical stains are useful markers to distinguish myxofibrosarcoma from myxoid liposarcoma.

No-cost manual method for preparation of tissue microarrays having high quality comparable to semiautomated methods

Manual tissue microarray (TMA) construction had been introduced to avoid the high cost of automated and semiautomated techniques. The cheapest and simplest technique for constructing manual TMA was that of using mechanical pencil tips. This study was carried out to modify this method, aiming to raise its quality to reach that of expensive ones. Some modifications were introduced to Shebl's technique. Two conventional mechanical pencil tips of different diameters were used to construct the recipient blocks. A source of mild heat was used, and blocks were incubated at 38°C overnight. With our modifications, 3 high-density TMA blocks were constructed. We successfully performed immunostaining without substantial tissue loss. Our modifications increased the number of cores per block and improved the stability of the cores within the paraffin block. This new, modified technique is a good alternative for expensive machines in many laboratories.

The expression of phospholipase A2 group X is inversely associated with metastasis in colorectal cancer

Among the secretory phospholipase A2s (sPLA2), sPLA2 group X (PLA2GX) has the most potent hydrolyzing activity toward phosphatidylcholine, and has recently been shown to be implicated in chronic inflammatory diseases. The aim of the present study was to investigate PLA2GX expression in colorectal cancer (CRC) and its correlation with patient clinicopathological features. The present study comprises a series of 158 patients who underwent surgical resection for primary CRC. PLA2GX expression in CRC tissues was examined by immunohistochemistry and compared with patient clinicopathological findings and survival. A total of 64% of the tumors expressed PLA2GX at high levels. Statistical analysis revealed that PLA2GX expression was inversely correlated with hematogenous metastasis (P=0.005). In the subgroup analysis, left-sided tumors with high PLA2GX expression showed an inverse correlation with lymph node metastasis (P=0.018) and hematogenous metastasis (P=0.017). Patients with high PLA2GX expression tended to have a longer disease-specific survival compared with those with low PLA2GX expression in left-sided, but not right-sided, CRC (P=0.08). In light of the present results, we suggest that PLA2GX has an inhibitory effect on the progression of CRC.

Phospholipase signalling networks in cancer

Phospholipases (PLC, PLD and PLA) are essential mediators of intracellular and intercellular signalling. They can function as phospholipid-hydrolysing enzymes that can generate many bioactive lipid mediators, such as diacylglycerol, phosphatidic acid, lysophosphatidic acid and arachidonic acid. Lipid mediators generated by phospholipases regulate multiple cellular processes that can promote tumorigenesis, including proliferation, migration, invasion and angiogenesis. Although many individual phospholipases have been extensively studied, how phospholipases regulate diverse cancer-associated cellular processes and the interplay between different phospholipases have yet to be fully elucidated. A thorough understanding of the cancer-associated signalling networks of phospholipases is necessary to determine whether these enzymes can be targeted therapeutically.

Prognostic significance of cytosolic phospholipase A2 expression in patients with colorectal cancer

PURPOSE

Cyclooxygenase-2 is believed to be an important enzyme in the pathogenesis of colorectal cancer (CRC). Cytosolic phospholipase A2 (cPLA2), also, have been suggested to be related to the carcinogenesis of CRC. The aim of this study was to investigate cPLA2 expression and its relationship with prognostic significance in CRC.

METHODS

Eighty-eight patients with colorectal cancer who underwent curative surgery were enrolled in this study. cPLA2 was examined in 88 primary CRCs by immunohistochemistry and we compared their expression with clinicopathologic findings, recurrence and survival in patients with CRC.

RESULTS

The expression of cPLA2 was positive in 54.5% (48/88). The expression of cPLA2 was not correlated with clinicopathologic parameters. However, cPLA2 expression was significantly related with vascular endothelial growth factor expression. Kaplan-Meier analysis didn't show any clinical significance in disease-free survival and overall survival according to cPLA2 expression.

CONCLUSION

These results suggest that cPLA2 expression was not associated with the prognosis of CRC. However, further large-scale studies are needed to clarify the prognostic effect of cPLA2 in CRC.

The expression and distribution of group IIA phospholipase A2 in human colorectal tumours

Secretory phospholipase A2 group IIA (IIA PLA2) is a protein shown to be increased in various human malignancies. The expression profile of this protein, however, is controversial in colorectal carcinoma. The aim of this study was to examine the distribution and expression of IIA PLA2 protein in benign, premalignant and malignant colorectal tumours as well as in peritumoural mucosa. Seven hyperplastic polyps, 24 adenomas and 83 colorectal carcinomas were stained with immunohistochemistry (IHC) for IIA PLA2. Four hyperplastic polyps, 12 adenomas and nine carcinomas were also evaluated for the sites of IIA PLA2 expression using mRNA in situ hybridisation (ISH). There was no immunoreactivity for IIA PLA2 in hyperplastic polyps. A total of 79% of adenomas and 31% of carcinomas showed IIA PLA2-immunopositive tumour cells in IHC, and the expression was localised to epithelial cells with ISH. In carcinomas, IIA PLA2-immunopositive apoptotic cells and necrosis were also found. The epithelial cells in the peritumoural mucosa showed immunopositivity for IIA PLA2 in 96% of cases, with considerably stronger intensity adjacent to carcinoma than in the more distal mucosa. Moreover, IIA PLA2-immunopositive malignant epithelial cells were found in 44% of cases in the invasive front of carcinomas. Our results suggest that the IIA PLA2 protein content is dramatically decreased in malignant colorectal tumours as compared with adenomas. The protein is also found in the apoptotic cells, necrosis, peritumoural mucosa and in the invasive front of carcinomas.