Higher skeletal muscle alpha2AMPK activation and lower energy charge and fat oxidation in men than in women during submaximal exercise

5'AMP-activated protein kinase (AMPK) is an energy sensor activated by perturbed cellular energy status such as during muscle contraction. Activated AMPK is thought to regulate several key metabolic pathways. We used sex comparison to investigate whether AMPK signalling in skeletal muscle regulates fat oxidation during exercise. Moderately trained women and men completed 90 min bicycle exercise at 60% VO2peak. Both AMPK Thr172 phosphorylation and alpha2AMPK activity were increased by exercise in men (approximately 200%, P < 0.001) but not significantly in women. The sex difference in muscle AMPK activation with exercise was accompanied by an increase in muscle free AMP (approximately 164%, P < 0.01), free AMP/ATP ratio (159%, P < 0.05), and creatine (approximately 42%, P < 0.001) in men but not in women (NS), suggesting that lack of AMPK activation in women was due to better maintenance of muscle cellular energy balance compared with men. During exercise, fat oxidation per kg lean body mass was higher in women than in men (P < 0.05). Regression analysis revealed that a higher proportion of type 1 muscle fibres (approximately 23%, P < 0.01) and a higher capillarization (approximately 23%, P < 0.05) in women than in men could partly explain the sex difference in alpha2AMPK activity (r = -0.54, P < 0.05) and fat oxidation (r = 0.64, P < 0.05) during exercise. On the other hand, fat oxidation appeared not to be regulated via AMPK. In conclusion, during prolonged submaximal exercise at 60% VO2peak, higher fat oxidation in women cannot be explained by higher AMPK signalling but is accompanied by improved muscle cellular energy balance in women probably due to sex specific muscle morphology.

Malonyl-CoA and carnitine in regulation of fat oxidation in human skeletal muscle during exercise

Intracellular mechanisms regulating fat oxidation were investigated in human skeletal muscle during exercise. Eight young, healthy, moderately trained men performed bicycle exercise (60 min, 65% peak O2 consumption) on two occasions, where they ingested either 1) a high-carbohydrate diet (H-CHO) or 2) a low-carbohydrate diet (L-CHO) before exercise to alter muscle glycogen content as well as to induce, respectively, low and high rates of fat oxidation. Leg fat oxidation was 122% higher during exercise in L-CHO than in H-CHO (P < 0.001). In keeping with this, the activity of alpha2-AMP-activated protein kinase (alpha2-AMPK) was increased twice as much in L-CHO as in H-CHO (P < 0.01) at 60 min of exercise. However, acetyl-CoA carboxylase (ACC)beta Ser221 phosphorylation was increased to the same extent (6-fold) under the two conditions. The concentration of malonyl-CoA was reduced 13% by exercise in both conditions (P < 0.05). Pyruvate dehydrogenase activity was higher during exercise in H-CHO than in L-CHO (P < 0.01). In H-CHO only, the concentrations of acetyl-CoA and acetylcarnitine were increased (P < 0.001), and the concentration of free carnitine was decreased (P < 0.01), by exercise. The data suggest that a decrease in the concentration of malonyl-CoA, secondary to alpha2-AMPK activation and ACC inhibition (by phosphorylation), contributes to the increase in fat oxidation observed at the onset of exercise regardless of muscle glycogen levels. They also suggest that, with high muscle glycogen, the availability of free carnitine may limit fat oxidation during exercise, due to its increased use for acetylcarnitine formation.

Extracellular collagenases and the endocytic receptor, urokinase plasminogen activator receptor-associated protein/Endo180, cooperate in fibroblast-mediated collagen degradation

The collagens of the extracellular matrix are the most abundant structural proteins in the mammalian body. In tissue remodeling and in the invasive growth of malignant tumors, collagens constitute an important barrier, and consequently, the turnover of collagen is a rate-limiting process in these events. A recently discovered turnover route with importance for tumor growth involves intracellular collagen degradation and is governed by the collagen receptor, urokinase plasminogen activator receptor-associated protein (uPARAP or Endo180). The interplay between this mechanism and extracellular collagenolysis is not known. In this report, we demonstrate the existence of a new, composite collagen breakdown pathway. Thus, fibroblast-mediated collagen degradation proceeds preferentially as a sequential mechanism in which extracellular collagenolysis is followed by uPARAP/Endo180-mediated endocytosis of large collagen fragments. First, we show that collagen that has been pre-cleaved by a mammalian collagenase is taken up much more efficiently than intact, native collagen by uPARAP/Endo180-positive cells. Second, we demonstrate that this preference is governed by the acquisition of a gelatin-like structure by the collagen, occurring upon collagenase-mediated cleavage under native conditions. Third, we demonstrate that the growth of uPARAP/Endo180-deficient fibroblasts on a native collagen matrix leads to substantial extracellular accumulation of well defined collagen fragments, whereas, wild-type fibroblasts possess the ability to direct an organized and complete degradation sequence comprising both the initial cleavage, the endocytic uptake, and the intracellular breakdown of collagen.

Dissociation of AMPK activity and ACCbeta phosphorylation in human muscle during prolonged exercise

During prolonged, low intensity exercise, the type of substrate utilized varies with time. If 5' AMP-activated protein kinase (AMPK) regulates muscle metabolism during exercise, signaling through AMPK would be expected to change in concordance with changes in substrate utilization. Six healthy, young males cycled (approximately 45% VO(2peak)) until exhaustion (approximately 3.5h). During exercise, leg glucose uptake and rate of glycogenolysis gradually decreased whereas free fatty acid uptake gradually increased. In the thigh muscle, the alpha AMPK subunits became progressively more phosphorylated on Thr(172) during exercise eliciting a parallel increase in alpha2 but not alpha1 AMPK activity. In contrast, after 1h of exercise, Ser(221) phosphorylation of acetyl-CoA carboxylase-beta (ACCbeta) peaked at 1h of exercise and returned to resting levels at exhaustion. Protein expression of alpha2 AMPK, alpha1 AMPK or ACCbeta did not change with time. These data suggest that AMPK signaling is not a key regulatory system of muscle substrate combustion during prolonged exercise and that marked activation of AMPK via phosphorylation is not sufficient to maintain an elevated ACCbeta Ser(221) phosphorylation during prolonged exercise.

Cytochrome P450 2C9 plays an important role in the regulation of exercise-induced skeletal muscle blood flow and oxygen uptake in humans

Previous studies show that exercise-induced hyperaemia is unaffected by systemic inhibition of nitric oxide synthase (NOS) and it has been proposed that this may be due to compensation by other vasodilators. We studied the involvement of cytochrome P450 2C9 (CYP 2C9) in the regulation of skeletal muscle blood flow in humans and the interaction between CYP 2C9 and NOS. Seven males performed knee extensor exercise. Blood flow was measured by thermodilution and blood samples were drawn frequently from the femoral artery and vein at rest, during exercise and in recovery. The protocol was repeated three times on the same day. The first and the third protocols were controls, and in the second protocol either the CYP 2C9 inhibitor sulfaphenazole alone, or sulfaphenazole in combination with the NOS inhibitor N(omega)-monomethyl-L-arginine (L-NMMA) were infused. Compared with control there was no difference in blood flow at any time with sulfaphenazole infusion (P > 0.05) whereas with infusion of sulfaphenazole and L-NMMA, blood flow during exercise was 16 +/- 4 % lower than in control (9 min: 3.67 +/- 0.31 vs. 4.29 +/- 0.20 l min(-1); P < 0.05). Oxygen uptake during exercise was 12 +/- 3 % lower (9 min: 525 +/- 46 vs. 594 +/- 24 ml min(-1); P < 0.05) with co-infusion of sulfaphenazole and L-NMMA, whereas oxygen uptake during sulfaphenazole infusion alone was not different from that of control (P > 0.05). The results demonstrate that CYP 2C9 plays an important role in the regulation of hyperaemia and oxygen uptake during exercise. Since inhibition of neither NOS nor CYP 2C9 alone affect skeletal muscle blood flow, an interaction between CYP 2C9 and NOS appears to exist so that a CYP-dependent vasodilator mechanism takes over when NO production is compromised.

Nitric oxide production is a proximal signaling event controlling exercise-induced mRNA expression in human skeletal muscle

Previous studies have described the magnitude and time course by which several genes are regulated within exercising skeletal muscle. These include interleukin-6 (IL-6), interleukin-8 (IL-8), heme oxygenase-1 (HO-1), and heat shock protein-72 (HSP72), which are involved in secondary signaling and preservation of intracellular environment. However, the primary signaling mechanisms coupling contraction to transcription are unknown. We hypothesized that exercise-induced nitric oxide (NO) production is an important signaling event for IL-6, IL-8, HO-1, and HSP72 expression in muscle. Twenty healthy males participated in the study. By real-time PCR, mRNA levels for 11 genes were determined in thigh muscle biopsies obtained 1) before and after 2 h knee extensor exercise without (control) and with concomitant NO synthase inhibition (nitro-L-arginine methyl ester, L-NAME, 5 mg x kg(-1)); or 2) before and after 2 h femoral artery infusion of the NO donor nitroglycerin (NTG, 1.5 microg x kg(-1) x min(-1)). L-NAME caused marked reductions in exercise-induced expression of 4 of 11 mRNAs including IL-6, IL-8, and HO-1. IL-6 protein release from the study leg to the circulation increased in the control but not in the L-NAME trial. NTG infusion significantly augmented expression of the mRNAs attenuated by L-NAME. These findings advance the novel concept that NO production contributes to regulation of gene expression in muscle during exercise. Subsequently, we sought evidence for involvement of AMP-activated kinase or nuclear factor kappa B, but found none.

The collagen receptor uPARAP/Endo180

The uPAR-associated protein (uPARAP/Endo180), a type-1 membrane protein belonging to the mannose receptor family, is an endocytic receptor for collagen. Through this endocytic function, the protein takes part in a previously unrecognized mechanism of collagen turnover. uPARAP/Endo180 can bind and internalize both intact and partially degraded collagens. In some turnover pathways, the function of the receptor probably involves an interplay with certain matrix-degrading proteases whereas, in other physiological processes, redundant mechanisms involving both endocytic and pericellular collagenolysis seem to operate in parallel. On certain cell types, uPARAP/Endo180 occurs in a complex with the urokinase plasminogen activator receptor (uPAR) where it seems to fulfill other functions in addition to collagenolysis. uPARAP/Endo180 is expressed on various mesenchymal cells, including subpopulations of fibroblasts, osteoblasts and chondrocytes, generally in conjunction with matrix turnover and collagenolysis. A striking expression is found in developing bone where the collagenolytic function of uPARAP/Endo180 is one of the rate-limiting steps in growth. In murine breast tumors, the endocytic function of the receptor in collagen breakdown seems to be involved in invasive tumor growth.

Detection of colorectal neoplasia: Combination of eight blood-based, cancer-associated protein biomarkers

Serological biomarkers may be an option for early detection of colorectal cancer (CRC). The present study assessed eight cancer-associated protein biomarkers in plasma from subjects undergoing first time ever colonoscopy due to symptoms attributable to colorectal neoplasia. Plasma AFP, CA19-9, CEA, hs-CRP, CyFra21-1, Ferritin, Galectin-3 and TIMP-1 were determined in EDTA-plasma using the Abbott ARCHITECT® automated immunoassay platform. Primary endpoints were detection of (i) CRC and high-risk adenoma and (ii) CRC. Logistic regression was performed. Final reduced models were constructed selecting the four biomarkers with the highest likelihood scores. Subjects (N = 4,698) were consecutively included during 2010-2012. Colonoscopy detected 512 CRC patients, 319 colonic cancer and 193 rectal cancer. Extra colonic malignancies were detected in 177 patients, 689 had adenomas of which 399 were high-risk, 1,342 had nonneoplastic bowell disease and 1,978 subjects had 'clean' colorectum. Univariable analysis demonstrated that all biomarkers were statistically significant. Multivariate logistic regression demonstrated that the blood-based biomarkers in combination significantly predicted the endpoints. The reduced model resulted in the selection of CEA, hs-CRP, CyFra21-1 and Ferritin for the two endpoints; AUCs were 0.76 and 0.84, respectively. The postive predictive value at 90% sensitivity was 25% for endpoint 1 and the negative predictive value was 93%. For endpoint 2, the postive predictive value was 18% and the negative predictive value was 97%. Combinations of serological protein biomarkers provided a significant identification of subjects with high risk of the presence of colorectal neoplasia. The present set of biomarkers could become important adjunct in early detection of CRC.

Dimerization of endogenous MT1-MMP is a regulatory step in the activation of the 72-kDa gelatinase MMP-2 on fibroblasts and fibrosarcoma cells

The secreted gelatinase matrix metalloprotease-2 (MMP-2) and the membrane-anchored matrix metalloprotease MT1-MMP (MMP-14), are central players in pericellular proteolysis in extracellular matrix degradation. In addition to possessing a direct collagenolytic and gelatinolytic activity, these enzymes take part in a cascade pathway in which MT1-MMP activates the MMP-2 proenzyme. This reaction occurs in an interplay with the matrix metalloprotease inhibitor, TIMP-2, and the proposed mechanism involves two molecules of MT1-MMP in complex with one TIMP-2 molecule. We provide positive evidence that proMMP-2 activation is governed by dimerization of MT1-MMP on the surface of fibroblasts and fibrosarcoma cells. Even in the absence of transfection and overexpression, dimerization of MT1-MMP markedly stimulated the formation of active MMP-2 products. The effect demonstrated here was brought about by a monoclonal antibody that binds specifically to MT1-MMP as shown by immunofluorescence experiments. The antibody has no effect on the catalytic activity. The effect on proMMP-2 activation involves MT1-MMP dimerization because it requires the divalent monoclonal antibody, with no effect obtained with monovalent Fab fragments. Since only a negligible level of proMMP-2 activation was obtained with MT1-MMP-expressing cells in the absence of dimerization, our results identify the dimerization event as a critical level of proteolytic cascade regulation.

A composite role of vitronectin and urokinase in the modulation of cell morphology upon expression of the urokinase receptor

The urokinase receptor, urokinase receptor (uPAR), is a glycosylphosphatidylinositol-anchored membrane protein engaged in pericellular proteolysis and cellular adhesion, migration, and modulation of cell morphology. A direct matrix adhesion is mediated through the binding of uPAR to vitronectin, and this event is followed by downstream effects including changes in the cytoskeletal organization. However, it remains unclear whether the adhesion through uPAR-vitronectin is the only event capable of initiating these morphological rearrangements or whether lateral interactions between uPAR and integrins can induce the same response. In this report, we show that both of these triggering mechanisms can be operative and that uPAR-dependent modulation of cell morphology can indeed occur independently of a direct vitronectin binding. Expression of wild-type uPAR on HEK293 cells led to pronounced vitronectin adhesion and cytoskeletal rearrangements, whereas a mutant uPAR, uPAR(W32A) with defective vitronectin binding, failed to induce both phenomena. However, upon saturation of uPAR(W32A) with the protease ligand, pro-uPA, or its receptor-binding domain, the ability to induce cytoskeletal rearrangements was restored, although this did not rescue the uPAR-vitronectin binding and adhesion capability. On the other hand, using other uPAR variants, we could show that uPAR-vitronectin adhesion is indeed capable and sufficient to induce the same morphological rearrangements. This was shown with cells expressing a different single-site mutant, uPAR(Y57A), in the presence of a synthetic uPAR-binding peptide, as well as with wild-type uPAR, which underwent cytoskeletal rearrangements even when cultivated in uPA-deficient serum. Blocking of integrins with an Arg-Gly-Asp-containing peptide counteracted the matrix contacts necessary to initiate the uPAR-dependent cytoskeletal rearrangements, whereas inactivation of the Rac signaling pathway in all cases suppressed the occurrence of the same events.

In vitro validation of an ultra-sensitive scanning fluorescence microscope for analysis of circulating tumor cells

Analysis of circulating tumor cells (CTC) holds promise of providing liquid biopsies from patients with cancer. However, current methods include enrichment procedures. We present a method (CytoTrack®), where CTC from 7.5 mL of blood is stained, analyzed and counted by a scanning fluorescence microscope. The method was validated by breast cancer cells (MCF-7) spiked in blood from healthy donors. The number of cells spiked in each blood sample was exactly determined by cell sorter and performed in three series of three samples spiked with 10, 33 or 100 cells in addition with three control samples for each series. The recovery rate of 10, 33 and 100 tumor cells in a blood sample was 55%, 70% and 78%, percent coefficient of variation (CV%) for samples was 59%, 32% and 18%, respectively. None of the control samples contained CTC. In conclusion, the method has been validated to highly sensitively detect breast cancer cells in spiking experiments and should be tested on blood samples from breast cancer patients. The method could benefit from automation that could reduce the CV%, and further optimization of the procedure to increase the recovery.

Protocol Outlines for Parts 1 and 2 of the Prospective Endoscopy III Study for the Early Detection of Colorectal Cancer: Validation of a Concept Based on Blood Biomarkers

BACKGROUND

Programs for population screening of colorectal cancer (CRC) have been implemented in several countries with fecal immunochemical testing (FIT) as the preferred platform. However, the major obstacle for a feces-based testing method is the limited compliance that reduces the clinical sensitivity for detection of participants with non-symptomatic CRC. Therefore, research approaches have been initiated to develop screening concepts based on biomarkers in blood. Preliminary results show that protein, genetic, epigenetic, and metabolomic components may be valuable in blood-based screening concepts, particularly when combinations of the various components appear to lead to significant improvements.

OBJECTIVES

The protocol described in this paper focuses on the validation of concepts based on biomarkers in blood in a major population screened by FIT.

METHODS

In Part 1, participants will be identified and included through the Danish CRC Screening Program comprising initial FIT and subsequent colonoscopy to those with a positive result. Blood samples will be collected from 8000 FIT-positive participants, who are offered subsequent colonoscopy. Findings and interventions at colonoscopy together with personal data including co-morbidity will be recorded. Blood samples and data will also be collected from 6000 arbitrarily chosen participants with negative FIT. In Part 2, blood samples and data will be collected from 30,000 FIT-negative participants three times within 4 years. The blood samples will be analyzed using various in-house and commercially available manual and automated analysis platforms.

RESULTS

We anticipate Part 1 to terminate late August 2016 and Part 2 to terminate late September 2022. The results from Parts 1 and 2 will be presented within 12 to 18 months from termination.

CONCLUSIONS

The purpose of this study is to improve the efficacy of identifying participants with neoplastic bowel lesions, to identify false negative participants, to identify participants at risk of interval neoplastic lesions, to improve the compliance in screening sessions, and to establish guidelines for out-patient follow-up of at-risk participants based on combinations of blood-based biomarkers.

Assessing HER2 amplification by IHC, FISH, and real-time polymerase chain reaction analysis (real-time PCR) following LCM in formalin-fixed paraffin embedded tissue from 40 women with ovarian cancer

We compare HER2 receptor amplification analysis by immunohistochemistry (IHC), fluorescence in situ hybridization (FISH), and real-time polymerase chain reaction (real-time PCR) DNA copy-number assay following laser capture microdissection (LCM) in formalin-fixed paraffin embedded tissue from 40 women with verified ovarian cancer. We speculate that LCM should result in a more accurate assessment of HER2 amplification in our real-time PCR assay compared with IHC and FISH. HER2 overexpression measured by IHC, FISH, or real-time PCR was found in 5.0%, 5.0%, and 22.5%, respectively. HER2 negative results measured by IHC, FISH, or real-time PCR were found in 95%, 92.5%, and 60.0%, respectively. Analysis failed for IHC, FISH, or real-time PCR in 0%, 2.5%, or 17.5% of cases. Concordance between IHC and FISH, IHC and real-time PCR, or FISH and real-time PCR were 89.7%, 72.7%, or 78.1%, respectively. Only few ovarian cancer patients were HER2 overexpressed measured by IHC or FISH and thus could be eligible for antibody-based therapy with trastuzumab (Herceptin). Interestingly, we find an increased number of HER2 positive patients by real-time PCR analysis on microdissected cancer cells, suggesting a number of HER2 positive patients not detected by current methods. Thus, the concept of quantitative measurement of HER2 on microdissected cancer cells should be explored further.

Retracing Circulating Tumour Cells for Biomarker Characterization after Enumeration

Background

Retracing and biomarker characterization of individual circulating tumour cells (CTCs) may potentially contribute to personalized metastatic cancer therapy. This is relevant when a biopsy of the metastasis is complicated or impossible to acquire.

Methods

A novel disc format was used to map and retrace individual CTCs from breast-cancer patients and nucleated cells from healthy blood donors using the CytoTrack platform. For proof of the retracing concept, CTC HER2 characterization by immunofluorescence was tested.

Results

CTCs were detected and enumerated in three of four blood samples from breast-cancer patients and the locations of each individual CTCs were mapped on the discs. Nucleated cells were retraced on seven discs with 96.6%±8.5% recovery on five fields of view on each disc. Shifting of field of view for retracing was measured to 4-29 μm. In a blood sample from a HER2-positive breast-cancer patient, CTC enumeration and mapping was followed by HER2 characterization and retracing to demonstrate downstream immunofluorescence analysis of the CTC.

Conclusion

Mapping and retracing of CTCs enables downstream analysis of individual CTCs for existing and future cancer genotypic and phenotypic biomarkers. Future studies will uncover this potential of the novel retracing technology.

Decrease by 50% of plasma IgA tissue transglutaminase antibody concentrations within 2 months after start of gluten-free diet in children with celiac disease used as a confirming diagnostic test

BACKGROUND

Histological examination of small bowel biopsies is normally the gold standard for the diagnosis of celiac disease (CD). The objective of this study was to investigate whether the rate of decreases in elevated plasma IgA tissue transglutaminase antibody (IgA-tTG) and/or IgG deamidated gliadin peptides antibody (IgG - DGP) concentrations could be used as a confirming test for CD in children on a gluten-free diet (GFD) when biopsy was omitted in the diagnostic process.

METHODS

In this retrospective study we compared children (≤18 years old) with a CD-confirming biopsy (n = 16) to children without a biopsy (n = 18). After initiation of GFD the antibody half-life (the time (T½) when the antibody concentration is 50% decreased) was determined in all children.

RESULTS

Children with a biopsy (IgA-tTG, T½ = 1.9 months; IgG - DGP, T½ = 2.2 months) and children without a biopsy (IgA-tTG, T½ = 1.6 months; IgG - DGP, T½ = 2.7 months) had comparable T½ (mean) results (p < 0.05) supporting that all children had the CD diagnosis.

CONCLUSIONS

When biopsy was omitted a rapid rate of decrease in CD antibody concentrations confirmed the CD diagnosis in children on GFD. The half-lives (T½) of IgA-tTG were less than 2 months in CD children.

Long-Term Comparison of 7 SARS-CoV-2 Antibody Assays in the North Zealand Covid-19 Cohort

Background

Throughout the coronavirus disease 2019 (Covid-19) pandemic numerous severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibody assays have been approved through Emergency Use Authorization and require further evaluation of sensitivity and specificity in clinical laboratory settings prior to implementation.

Methods

We included 1733 samples from 375 PCR-confirmed SARS-CoV-2–positive individuals of the North Zealand Covid-19 Cohort in an 8-month period. We investigated diagnostic sensitivity and specificity against consensus and PCR and interassay agreement over time for 5 SARS-CoV-2 immunoassays [Roche-nucleocapsid (NC)-total, Roche-receptor binding domain (RBD)-total, Siemens-RBD-IgG, Siemens-RBD-total, Thermo Fisher Scientific (TFS)-RBD-IgG] commercially available on automated platforms and 2 ELISA assays (TFS-RBD-total, Wantai-RBD-total).

Results

Early interassay discrepancy in up to 49% of samples decreased steadily during the first 18 days. By day 18, all assays had reached a plateau between 82.3% and 90.5% seropositivity compared to PCR. Assays ranked by closest agreement with the consensus model beyond day 18 (sensitivity/specificity against consensus) were as follows: Roche-RBD-total, 99.8%/100.0%; Wantai-RBD-total, 99.8%/99.7%; Roche-NC-total, 97.8%/100.0%; Siemens-RBD-total, 98.0%/98.7%; TFS-RBD-total, 96.9%/99.7%; TFS-RBD-IgG, 91.5%/100.0%; and Siemens-RBD-IgG, 94.6%/89.9%. We found that 7.8% of PCR-positive patients remained seronegative in all assays throughout the study.

Conclusions

All included assays had sensitivities against consensus >90% past day 18. For the current recommended use of antibody assays to detect former, undocumented Covid-19, our data suggest the use of total antibody assays rather than IgG-specific assays due to higher long-term sensitivity. Finally, a nonresponding subpopulation of 7.8% in our cohort with persistent seronegative results raises concern of a possible substantial number of people with continued low protection following natural SARS-CoV-2 infection.

Cryopreservation of Circulating Tumor Cells for Enumeration and Characterization

BACKGROUND

A blood sample containing circulating tumor cells (CTCs) may serve as a surrogate for metastasis in invasive cancer. Cryopreservation will provide new opportunities in management of clinical samples in the laboratory and allow collection of samples over time for future analysis of existing and upcoming cancer biomarkers.

METHODS

Blood samples from healthy volunteers were spiked with high (∼500) and low (∼50) number of tumor cells from culture. The samples were stored at -80C with cryopreservative dimethyl sulfoxide mixed with Roswell Park Memorial Institute 1640 medium. Flow cytometry tested if cryopreservation affected specific biomarkers regularly used to detect CTCs, i.e. cytokeratin (CK) and epithelial cell adhesion molecule (EpCAM) and white blood cell specific lymphocyte common antigen (CD45). After various time intervals (up to 6 months), samples were thawed and tumor cell recovery (enumeration) was examined. Clinical samples may differ from cell line studies, so the cryopreservation protocol was tested on 17 patients with invasive breast cancer and tumor cell recovery was examined. Two blood samples were drawn from each patient.

RESULTS

Biomarkers, CK, CD45, and EpCAM, were not affected by the freezing and thawing procedures. Cryopreserved samples (n = 2) spiked with a high number of tumor cells (∼500) had a ∼90% recovery compared with the spiked fresh samples. In samples spiked with lower numbers of tumor cells (median = 43 in n = 5 samples), the recovery was 63% after cryopreservation (median 27 tumor cells), p = 0.03. With an even lower number of spiked tumor cells (median = 3 in n = 8 samples), the recovery rate of tumor cells after cryopreservation did not seem to be affected (median = 8), p = 0.09. Time of cryopreservation did not affect recovery. When testing the effect of cryopreservation on enumeration in clinical samples, no difference was observed in the number of CTCs between the fresh and the cryopreserved samples based on n = 17 pairs, p = 0.83; however, the variation was large. This large variation was confirmed by clinically paired fresh samples (n = 64 pairs), where 95% of the samples (<30 CTCs) vary in number up to ±15 CTCs, p = 0.18.

CONCLUSIONS

A small loss of CTCs after cryopreservation may be expected; however, cryopreservation of CTCs for biomarker characterization for clinical applications seems promising.

CytoTrack Analysis Reveals Low Presence of Circulating Tumor Cells in the Perioperative Period in Patients with Non-metastatic Colorectal Cancer

BACKGROUND/AIM

Detection of circulating tumor cells in the perioperative period predicts poor prognosis in patients with colorectal cancer. There is only one Food and Drug Administration-approved method for such detection, CellSearch, for which results have been inconsistent. A new immunological method, CytoTrack, has shown promising results in patients with breast cancer. The aim of this study was to evaluate detection of circulating tumor cells in the peripheral blood of patients with non-metastatic colorectal cancer with CytoTrack, and investigate if there is a correlation between presence of circulating tumor cells and Union for International Cancer Control (UICC) stage and if surgery itself results in the release of circulating tumor cells.

PATIENTS AND METHODS

A prospective study was conducted including patients with colorectal cancer UICC stage I-III who underwent minimally-invasive surgery. Patients with previous cancer diagnosis or neoadjuvant chemo/ radiotherapy were excluded. Blood samples were collected from all included patients one day prior to and one day after surgery. Detection of circulating tumor cells was performed using CytoTrack.

RESULTS

A total of 20 patients were consecutively included. Circulating tumor cells were detected in one preoperative sample and two postoperative samples.

CONCLUSION

The presence of circulating tumor cells is rare in patients with non-metastatic colorectal cancer and the new method we used, CytoTrack, was only able to detect circulating tumor cells in three out of 40 blood samples. More specific antibodies are needed to identify circulating tumor cells in these patients.

Clean Colorectum at Diagnostic Colonoscopy: Subsequent Detection of Extracolonic Malignancies by Plasma Protein Biomarkers?

Introduction

Most of the subjects undergoing diagnostic colonoscopy do not have neoplastic bowel lesions. Potentially, some of the symptoms may therefore be caused by extracolonic malignancy, and subjects with persisting symptoms may need subsequent examinations. Blood-based, cancer-associated biomarkers may aid in directing the examinations for other specific malignant diseases.

Methods

EDTA plasma samples available from a previous prospective study of subjects undergoing diagnostic colonoscopy were used for analysis of 18 protein biomarkers. The study population of 3732 subjects included 400 patients with colorectal cancer (CRC) and 177 patients with extracolonic malignancies. Univariable analysis of the association of specific biomarkers and extracolonic cancers included those with 10 or more cases. Subsequently, reduced models of 4 or 6 biomarkers, respectively, were established by choosing those with the highest likelihood; age and sex were included as well.

Results

Univariable analyses showed that CyFra21-1 had an area under curve (AUC) of 0.87 for lung cancers (n = 33), CA19-9 had an AUC of 0.85 for pancreatic cancer (n = 22), CA125 had an AUC of 0.95 for ovary cancer (n = 16), B2M had an AUC of 0.81 for non-Hodgkin lymphoma (n = 12), and total prostate-specific antigen had an AUC of 0.99 for prostate cancer (n = 10). The multivariable analysis of 4 or 6 biomarkers plus age and sex as explanatory variables showed AUCs of 0.82 to 0.85 both for extracolonic cancers and CRC. The 4 biomarkers included in the model for detection of extracolonic cancers were CA125, hsCRP, CA19-9, and CyFra21-1; the 2 additional for the 6 biomarkers model were CEA and Galectin-3. Similarly, the 4 biomarkers included in the model for detection of CRC were CEA, CyFra21-1, Ferritin, and HE4; the two additional for the 6 biomarkers model were hsCRP and Pepsinogen 2.

Conclusions

Results of this study indicate that it may be possible to detect subjects that have an increased risk of extracolonic cancer following a colonoscopy without findings of neoplastic lesions. Combinations of various protein biomarkers may direct subsequent examination after colonoscopy with clean colorectum. The results, although preliminary, may form the basis for additional research directed both for primary examinations of subjects with symptoms of malignancy and subsequent examinations after colonoscopy.

Feasibility of single-cell analysis of model cancer and foetal cells in blood after isolation by cell picking

The objective of the present feasibility study was to transfer single cell line cells to either microscopy slides for downstream immune characterization or to polymerase chain reaction tubes for downstream DNA quantitation. Tumour cell lines, SKBR3 and MCF7 and trophoblast cell line JEG-3 were spiked in healthy donor blood. The CytoTrack system was used to scan the spiked blood samples to identify target cells. Individual target cells were identified, picked by use of a CytoPicker and deposited to either a microscopic slide or a polymerase chain reaction tube (PCR). Single tumour cells on microscopic slides were further immunostained with human epidermal growth factor receptor 2 (Her2) and epithelial cell adhesion molecule (EpCAM). From the picked cells in polymerase chain reaction tubes, DNA was amplified, quantified and used for Short Tandem Repeat genotyping. Depositing rare cells to microscopy slides was laborious with only five cells per hour. In this study with a trained operator, the picked cells had an 80.5% recovery rate. Depositing single trophoblast cells in PCR tubes was a faster process with 10 cells in 5 min. Immunostaining of isolated cells by both Her2 and EpCAM was possible but showed varying staining intensity. Presence of trophoblasts and contaminating white blood cells in PCR tubes after cell picking was confirmed based on DNA yield and mixed Short Tandem Repeat profiles in five out of eight samples. Using the CytoPicker tool, single tumour and trophoblast cells were successfully isolated and moved from blood samples, allowing subsequent immunostaining or Short Tandem Repeat genotyping.

Elevated prostate specific antigen and reduced 10-year survival among a cohort of Danish men consecutively referred from primary care to an urological department during 2005-2006

It remains unclear whether total prostate specific antigen (tPSA) or complex PSA (cPSA) has the best diagnostic performance. Additionally, the utility of percentage free PSA (%fPSA) is still debated. Our objectives were to compare the diagnostic performances of tPSA, cPSA, and %fPSA among patients referred from GP to an Urological Specialist and to investigate prognostic factors and survival in the cohort. A total of 1261 consecutive male patients without previously known prostate cancer (PCa) were referred to the same Department of Urology during June 2005 to August 2006. Some 299 patients were diagnosed with PCa and 962 patients were found without PCa. Among the PCa patients, the median age, tPSA, cPSA, and %fPSA levels were 70.8 years, 13.4 μg/L, 10.8 μg/L, and 12.6%. For patients without PCa the results were 67.5 years, 2.5 μg/L, 1.9 μg/L, and 24.9%. The sensitivity, specificity, PVpos, PVneg, and efficiency of tPSA and cPSA were overlapping (p > .05). In the tPSA interval >4 μg/L - ≤20 μg/L, %fPSA excluded PCa with a PVneg of 72.4%; 38.5% of PCa patients had a tPSA concentration >20 μg/L at the time of referral and these patients had a reduced 10-year survival as compared to patients with tPSA concentrations ≤20 μg/L. In conclusion, tPSA and cPSA showed similar diagnostic performances. %fPSA provided additional diagnostic information at tPSA concentrations >4 μg - ≤20 μg/L. The high percentage of patients with tPSA concentrations >20 μg/L indicate delayed use of tPSA resulting in advanced disease at presentation and reduced patient survival.