Alterations in complex lipids in tumor tissue of patients with colorectal cancer

Background Accumulating evidence indicates alterations in lipid metabolism and lipid composition in neoplastic tissue. Earlier nuclear magnetic resonance studies showed that the contents of major lipid groups, such as triacylglycerols, phospholipids and cholesterol, are changed in colon cancer tissue. Methods In this study, a more detailed analysis of lipids in cancer and tumor adjacent tissues from colorectal cancer patients, using liquid chromatography–mass spectrometry, allowed for comparison of 199 different lipids between cancer tissue and tumor adjacent tissue using principal component analysis. Results Significant differences were found in 67 lipid compounds between the two types of tissue; many of these lipid compounds are bioactive lipids such as ceramides, lysophospholipids or sterols and can influence the development of cancer. Additionally, increased levels of phospholipids and sphingolipids were present, which are major components of the cell membrane, and increases in these lipids can lead to changes in cell membrane properties. Conclusions This study showed that many complex lipids are significantly increased or decreased in colon cancer tissue, reflecting significant alterations in lipid metabolism. This knowledge can be used for the selection of potential molecular targets of novel anticancer strategies based on the modulation of lipid metabolism and the composition of the cell membrane in colorectal cancer cells.

Research for Expression and Prognostic Value of GABRD in Colon Cancer and Coexpressed Gene Network Construction Based on Data Mining

Colon cancer is one of the top five cancers with the highest incidence rate in the world. In order to better understand the pathogenesis and progression of colon cancer, it is still necessary to investigate the abnormally expressed genes in cancer tissue. In this study, the Oncomine database was used for expression analysis, and it was found that the expression level of gamma-aminobutyric acid type A receptor subunit delta (GABRD) gene was upregulated in colon cancer tissue compared with that in normal tissue. UALCAN was used to analyze the expression of GABRD in different groups of age, gender, cancer stage, N stage, and histological subtype. Then, it was also found that the expression of GABRD in each subgroup of colon cancer tissue was all high compared with that in normal tissue. LinkedOmics was used to screen out the differentially expressed genes related to GABRD expression in colon cancer. GO annotation and KEGG pathway enrichment analyses found that the correlated genes may be related to breast cancer, human papillomavirus infection, Notch signaling pathway, and other pathways. Thereafter, GSEA was performed to obtain GABRD-related kinases, miRNAs, and transcription factors, and gene interaction networks were constructed. It was found that GABRD may be involved in cell cycle regulation. Finally, websites like GEPIA were used to detect the predictive ability of GABRD on the prognosis of patients with colon cancer. Kaplan-Meier analysis suggested that the upregulation of GABRD expression was related to the poor prognosis of patients with colon cancer. Overall, in this study, the potential role and prognostic ability of GABRD in colon cancer were explored through data mining, which can be a clue for further research on GABRD.

Decreased concentrations of intracellular signaling proteins in colon cancer patients with BRAF mutations

The activation of intracellular signaling pathways plays a critical role in cancer pathogenesis. The current study aims to quantify intracellular signaling proteins in localized colon cancer tissue to investigate the prognostic value of these biomarkers and elucidate their possible relations to mutation status. Colon cancer tissue and autologous reference tissue were collected from 176 patients who underwent colon cancer surgery. Assays were developed to quantify ERK, AKT and cyclin d using single-molecule array technology. KRAS/BRAF/PIK3CA mutation status was determined using droplet digital PCR. Patients with BRAF mutations had decreased concentrations of ERK (p = 0.0003), AKT (p = 0.0001) and cyclin d (p = 0.003), while no significant differences were found between patients with KRAS mutations and wild-type patients. None of the investigated proteins were associated with disease-free survival or overall survival when all patients were included. However, when patients were stratified according to mutation status, significant correlations with overall survival were seen for patients with BRAF mutations and AKT (p = 0.002) or ERK (p = 0.03) and for KRAS mutations and cyclin d (p = 0.01). Conclusions: A strong correlation exists between intracellular signaling protein concentrations and mutational BRAF status. Overall survival in colon cancer patients depends on both gene mutation status and signaling protein concentrations.

Developing single molecule methods for measuring the pathway proteins ERK, AKT, cyclin d and p70s6k in localized colon cancer in relation to mutation status

BackgroundThe aim of this study was to quantify the intracellular pathway proteins ERK, AKT, cyclin d and p70s6k in localized colon cancer tissue to investigate the possible prognostic values and the ability to be used as screening markers for upstream mutations.MethodsColon cancer tissue and autologous reference tissue were collected from 176 patients who underwent surgery for colon cancer. Assays for quantifying ERK, AKT, cyclin d and p70s6k proteins were developed using single molecule array (Simoa). KRAS/BRAF/PIK3CA mutation status was determined using droplet digital PCR.ResultsPatients with BRAF mutations had decreased concentrations of ERK (p=0.0002), AKT (p=0.00004) and cyclin d (p=0.001) while no significant differences were found between patients with KRAS mutations and Wild type (Wt) patients. None of the investigated protein concentrations were associated with disease free survival or overall survival, if including all patients. However, when stratifying according to mutation status, significant correlations to overall survival were seen for patients with BRAF mutations and AKT (p=0.003) or ERK (p=0.046) and for patients with KRAS mutations and p70s6k (p=0.04). Furthermore, the combination of genetic mutations, stage 2 disease, and all of the investigated pathway proteins showed significant correlations to overall survival.ConclusionsThere is a strong correlation between pathway protein concentrations and mutational BRAF status. Overall survival in colon cancer patients depend both on gene mutation status and pathway protein concentrations. As significant correlations were found between BRAF mutations and ERK, AKT and cyclin d, concentration measurements of these pathway proteins might be useful as screening for upstream mutations.

Upregulated Na+/H+-Exchange Protects Human Colon Cancer Tissue against Intracellular Acidification

Increased metabolism accelerates local acid production in cancer tissue. The mechanisms eliminating acidic waste products from human colon cancer tissue represent promising therapeutic targets for pharmacological manipulation in order to improve prognosis for the increasing number of patients with colon cancer. We sampled biopsies of human colonic adenocarcinomas and matched normal colon tissue from patients undergoing colon cancer surgery. We measured steady-state intracellular pH and rates of net acid extrusion in freshly isolated human colonic crypts based on fluorescence microscopy. Net acid extrusion was almost entirely (>95%) Na+-dependent. The capacity for net acid extrusion was increased and steady-state intracellular pH elevated around 0.5 in crypts from colon cancer tissue compared with normal colon tissue irrespective of whether they were investigated in the presence or absence of CO2/HCO3–. The accelerated net acid extrusion from the human colon cancer tissue was sensitive to the Na+/H+-exchange inhibitor cariporide. We conclude that enhanced net acid extrusion via Na+/H+-exchange elevates intracellular pH in human colon cancer tissue.