Evaluation of Blood Soluble CD26 as a Complementary Biomarker for Colorectal Cancer Screening Programs

Fecal hemoglobin immunodetection (FIT) in combination with endoscopy has been implemented to reduce mortality from colorectal cancer (CRC), although there are issues that can be improved in relation to participation rates. We studied whether the blood biomarker soluble-CD26 (sCD26), related at least in part to the immune system and inflammation, and/or its dipeptidyl peptidase enzyme activity (DPP4), could help reduce false positives. In a cohort of 1703 individuals who underwent colonoscopy and had a serum sample, sCD26 and DPP4 activity showed statistically significant differences regarding sex and age. According to the colonoscopy findings, sCD26 and DPP4 activity progressively decreased in advanced adenomas and CRC, with statistically significant differences, even between both groups; 918 of them had a FIT result (n = 596 positive cases) with approximately 70% of these (n = 412) false positives. With cut-offs of 440 ng/mL for sCD26, 42 mU/mL for DPP4, and 11 ng/mU for their ratio, the combined information of the three biomarkers (at least positive for one biomarker) identified almost all advanced adenomas and CRC cases in the FIT cohort with approximately half of the false positives compared to FIT. A sequential testing strategy with FIT and our blood biomarker test is proposed.

Surface expression marker profile in colon cancer cell lines and sphere-derived cells suggests complexity in CD26+ cancer stem cells subsets

Taking advantage of eight established cell lines from colorectal cancer patients at different stages of the disease and the fact that all of them could form spheres, cell surface biomarkers of cancer stem cells and epithelial-mesenchymal transition were tested. The aim was to investigate cancer stem cells and metastatic stem cells in order to provide functional characterization of circulating tumor cells and promote the development of new anti-metastatic therapies. Our model showed an important heterogeneity in EpCAM, CD133, CD44, LGR5, CD26 and E-cadherin expression. We showed the presence of a subset of E-cadherin⁺ (some cells being E-cadherin^high) expressing CD26⁺ (or CD26^high) together with the well-known CSC markers LGR5 and EpCAM^high, sometimes in the absence of CD44 or CD133. The already described CD26⁺/E-cadherin^low or ^negative and CD26⁺/EpCAM⁻/CD133⁻ subsets were also present. Cell division drastically affected the expression of all markers, in particular E-cadherin, so new-born cells resembled mesenchymal cells in surface staining. CD26 and/or dipeptidyl peptidase 4 inhibitors have already shown anti-metastatic effects in pre-clinical models, and the existence of these CD26⁺ subsets may help further research against cancer metastasis.

Summary: In our model of eight established cell lines from colorectal cancer patients we show the presence of different putative cancer stem cell (CSC) subsets with expression of CD26/DPP4.

Relevance of matrix metalloproteases in non-small cell lung cancer diagnosis

BACKGROUND

The need for novel biomarkers that could aid in non-small cell lung cancer (NSCLC) detection, together with the relevance of Matrix Metalloproteases (MMPs) -1, -2, -7, -9 and -10 in lung tumorigenesis, prompted us to assess the diagnostic usefulness of these MMPs and the Tissue Inhibitor of Metalloproteinase (TIMP) -1 in NSCLC patients.

METHODS

Markers were evaluated in an initial study cohort (19 NSCLC cases and 19 healthy controls). Those that better performed were analyzed in a larger sample including patients with benign lung diseases. Serum MMPs and TIMP-1 were determined by multiplexed immunoassays. Logistic regression was employed for multivariate analysis of biomarker combinations.

RESULTS

MMPs and TIMP-1 were elevated in the serum of NSCLC patients compared to healthy controls. MMP-1, -7 and -9 performed at best and were further evaluated in the sample including benign pathologies, corroborating the superiority of MMP-9 in NSCLC discrimination, also at early-stage NSCLC. The optimal diagnostic value was obtained with the model including MMP-9, gender, age and smoking history, that demonstrated an AUC of 0.787, 85.54% sensitivity and 64.89% specificity.

CONCLUSION

Our results suggest that MMP-9 is a potential biomarker for NSCLC diagnosis and its combined measurement with other biomarkers could improve NSCLC detection.

A simple electroelution method for rapid protein purification: isolation and antibody production of alpha toxin from Clostridium septicum

Clostridium septicum produces a number of diseases in human and farm animals which, in most of the cases, are fatal without clinical intervention. Alpha toxin is an important agent and the unique lethal virulent factor produced by Clostridium septicum. This toxin is haemolytic, highly lethal and necrotizing activities but is being used as an antigen to develop animal vaccines. The aim of this study was to isolate the alpha toxin of Clostridium septicum and produce highly specific antibodies against it. In this work, we have developed a simple and efficient method for alpha toxin purification, based on electroelution that can be used as a time-saving method for purifying proteins. This technique avoids contamination by other proteins that could appear during other protein purification techniques such chromatography. The highly purified toxin was used to produce polyclonal antibodies. The specificity of the antibodies was tested by western blot and these antibodies can be applied to the quantitative determination of alpha toxin by slot blot.