We have compiled from literature and other sources a list of 1261 proteins believed to be differentially expressed in human cancer. These proteins, only some of which have been detected in plasma to date, represent a population of candidate plasma biomarkers that could be useful in early cancer detection and monitoring given sufficiently sensitive specific assays. We have begun to prioritize these markers for future validation by frequency of literature citations, both total and as a function of time. The candidates include proteins involved in oncogenesis, angiogenesis, development, differentiation, proliferation, apoptosis, hematopoiesis, immune and hormonal responses, cell signaling, nucleotide function, hydrolysis, cellular homing, cell cycle and structure, the acute phase response and hormonal control. Many have been detected in studies of tissue or nuclear components; nevertheless we hypothesize that most if not all should be present in plasma at some level. Of the 1261 candidates only 9 have been approved as "tumor associated antigens" by the FDA. We propose that systematic collection and large-scale validation of candidate biomarkers would fill the gap currently existing between basic research and clinical use of advanced diagnostics.

/pdf/a-list-of-candidate-cancer-biomarkers-for-targeted-lu8garq70x.pdf

A list of candidate cancer biomarkers for targeted proteomics.

Galectin-3 is a β-galactoside-specific lectin implicated in diverse processes involved in cellular interactions. Recently, the Mac-2-binding protein, a heavily N-glycosylated secreted protein with a subunit Mr of 97,000, was identified as its ligand. The present study characterizes the interaction between galectin-3 and Mac-2-binding protein in whole cells and measures their relative expression levels. Incubation of A375 cells with affinity-purified Mac-2-binding protein resulted in its binding to galectin-3 on the cell surface in a specific carbohydrate-dependent manner. Mac-2-binding protein also induced homotypic cell aggregation, which was inhibited by lactose or Fab9 fragments of an anti-galectin-3 antibody. Northern blotting analysis revealed differences in the transcriptional regulation of galectin-3 and Mac-2-binding protein. These results provide the first direct evidence for a Mac-2-binding protein function and suggest that it may play a role in tumor cell embolization during metastasis through interaction with galectin-3.

/pdf/interactions-between-galectin-3-and-mac-2-binding-protein-4rws2ku5cs.pdf

Interactions between Galectin-3 and Mac-2-Binding Protein Mediate Cell-Cell Adhesion

Human Mac-2 binding protein (M2BP) was prepared in recombinant form from the culture medium of 293 kidney cells and consisted of a 92 kDa subunit. The protein was obtained in a native state as indicated by CD spectroscopy, demonstrating alpha-helical and beta-type structure, and by protease resistance and immunological analysis. It was highly modified by N- and O-glycosylation but not by glycosaminoglycans. Ultracentrifugation showed non-covalent association into oligomers with molar masses of 1000-1500 kDa. Electron microscopy showed ring-like shapes with diameters of 30-40 nm. M2BP bound in solid-phase assays to collagens IV, V and VI, fibronectin and nidogen, but not to fibrillar collagens I and III or other basement membrane proteins. The protein also mediated adhesion of cell lines at comparable strength with laminin. Adhesion to M2BP was inhibited by antibodies to integrin beta1 subunits but not to alpha2 and alpha6 subunits, RGD peptide or lactose. This distinguishes cell adhesion of M2BP from that of laminin and excludes involvement of lactose-binding galectin-3. Immunological assays demonstrated variable secretion by cultured human cells of M2BP, which was detected in the extracellular matrix of several mouse tissues.

Mac‐2 binding protein is a cell‐adhesive protein of the extracellular matrix which self‐assembles into ring‐like structures and binds β1 integrins, collagens and fibronectin

Proteomic technologies provide an excellent means for analysis of body fluids for cataloging protein constituents and identifying biomarkers for early detection of cancers. The biomarkers currently available for pancreatic cancer, such as CA19-9, lack adequate sensitivity and specificity contributing to late diagnosis of this deadly disease. In this study, we carried out a comprehensive characterization of the “pancreatic juice proteome” in patients with pancreatic adenocarcinoma. Pancreatic juice was first fractionated by 1-dimensional gel electrophoresis and subsequently analyzed by liquid chromatography tandem mass spectrometry (LC−MS/MS). A total of 170 unique proteins were identified including known pancreatic cancer tumor markers (e.g., CEA, MUC1) and proteins overexpressed in pancreatic cancers (e.g., hepatocarcinoma−intestine−pancreas/pancreatitis-associated protein (HIP/PAP) and lipocalin 2). In addition, we identified a number of proteins that have not been previously described in pancreatic jui...

Comprehensive proteomic analysis of human pancreatic juice

The secreted tumor-associated antigen 90K is a potent immune stimulator.

Monoclonal antibody SP-2 to the tumour-associated antigen 90K was generated by immunisation with conditioned medium of human breast cancer cells. We investigated whether circulating levels of 90K can influence the prognosis of patients with breast cancer. Serum samples were obtained from 425 patients with histologically proven breast cancer with no clinical evidence of disease after surgery (NED) and in 310 patients with metastatic disease. Serum 90K was determined by a new immunoradiometric assay (IRMA). Antigen levels in NED patients were elevated in 18.5% of cases, mean levels being higher than in healthy controls (P = 0.001). Among 375 evaluable patients, the 75-month overall survival for 90K-negative ( 11 U ml-1) patients was 78% and 53% respectively (P = 0.004). The prognostic value of 90K appeared to be limited to patients with node-positive disease. Number of metastatic axillary lymph nodes and level of 90K antigen were the only independent variables for predicting overall survival. Patients with metastatic breast cancer had elevated 90K in 51.3% of cases. High 90K levels were significantly associated with the presence of metastases to liver, shorter disease-free interval and younger age. We conclude that an elevated 90K antigen level in serum is a predictor of poor prognosis in breast cancer.

Prognostic value of a novel circulating serum 90K antigen in breast cancer.

We report a case of carcinosarcoma and separate neuroendocrine malignant tumor of the gastric stump. The case is interesting because of its unique pathological features and it confirms the role of the gastric stump as a very important «malignancy promoter»

Carcinosarcoma and separate neuroendocrine malignant tumor of a malignancy promoter, the gastric stump.

The immunohistochemical expression of HER-2/neu and cytofluorimetric data were retrospectively analyzed in a group of primary advanced ovarian cancers. Thirty-three out of 94 (35%) cases showed a specific p185/neu immunoreaction. No correlation between p185/neu expression and any of the clinico-pathologic parameters examined was observed. As far as cytofluorimetric data are concerned, 38 out of 69 (55%) of the tumors were diploid (DNA index = 1) while 31 (45%) were aneuploid (DNA index from 1.10 to 2.50 with a median value of 1.50). Ovarian tumors were defined as of low and high S-phase fraction in 68% and 32% of the cases, respectively. Tumor ploidy and S-phase fraction did not correlate with the clinico-pathologic characteristics or p185/neu oncoprotein expression. Aneuploid tumors had a higher S-phase fraction (mean: 15.81 +/- 13.44) than diploid tumors (mean: 8.89 +/- 7.98) (P < 0.01). p185/neu expression failed to affect significantly both overall and progression free survival. On the other hand tumor ploidy was found to be related to the prognosis of advanced ovarian cancer patients although the difference was not statistically significant. As far as progression free survival is concerned, the median time to recurrence was not reached for diploid cases whereas it was 21 months for aneuploid cases (P < 0.05). The 5-year survival for patients with a low S-phase fraction (58%) was significantly higher than for patients with high S-phase fraction tumors (28%) (P < 0.01). Median time to recurrence was 48 and 17 months for low and high S-phase fraction tumor patients, respectively (P < 0.05). However, in a multivariate analysis both tumor ploidy and S-phase fraction did not retain their prognostic value. The assessment of the role of the parameters examined in improving the prognostic characterization of ovarian cancer patients should be investigated in large multicenter clinical trials.

https://ijgc.bmj.com/content/ijgc/3/5/271.full.pdf

Expression of HER-2/neu oncoprotein, DNA-ploidy and S-phase fraction in advanced ovarian cancer.

Levels of a 90,000 daltons monoclonal antibody-defined tumor-associated antigen, termed 90K, were measured in the serum from 649 patients with various types of cancer and 1215 patients infected by the human immunodeficiency virus (HIV). Significantly increased 90K serum levels (12.1 +/- 0.5 U/ml) were found in cancer patients with respect to healthy controls (5.7 +/- 0.3 U/ml), with the highest levels in neoplasms of the breast, lung and gastrointestinal tract. In 355 patients with breast cancer, the elevation of serum 90K levels was more pronounced at advanced stages of disease. Mean levels of 90K for 1215 HIV-infected subjects (21.2 +/- 0.8 U/ml) were significantly higher than controls and cancer patients, and the levels progressively increased with disease worsening from asymptomatic infection to full blown AIDS. These data suggest that 90K is not merely a tumor-associated antigen and lead us to postulate it to be a signalling molecule whose production might be related to the immune deficit caused by pathogenetic events such as neoplastic progression and virus infection.

Elevated serum levels of a 90,000 daltons tumor-associated antigen in cancer and in infection by human immunodeficiency virus (HIV).

Interferon-alpha (IFN-a) and interleukin-2 (IL-2) are cytokines with a variety of immune effects that suggest they might be useful anticancer agents. Indeed, antitumor responses to IFN-a or IL-2 have been documented in various types of experimental and human malignancies, especially renal-cell carcinoma and malignant melanoma. Published clinical trials of IFN-alpha and IL-2 in these cancers have reported response rates in the order of 20% (for a review see Foon, 1989). IL-2 therapy is generally administered by i.v. bolus or continuous infusion at doses of 18 million IU m2 day or higher. Because of the severity of adverse reactions, these high-dose i.v. regimens require continous monitoring or even the admission of patients to intensive-care units (Rosenberg et al., 1988a; Lee R.E. et al., 1989). Some preclinical data have documented that the combination of IFN-a and IL-2 produces a better antitumour activity with respect to the single agent (Cameron et al., 1988; ligo et al., 1988; Rosenberg et al., 1988b). The mechanism of this synergism is unknown. One hypothesis is that IFN-a up-regulates the expression of MHC class I and class II antigens (Faltynek & Oppenheim, 1988; Goldstein et al., 1989) and that the response to IL-2 treatment appears to be strictly related to the expression of these antigens (Atzpodien et al., 1990a). Based on these data some investigators have conducted clinical trials using reduced doses of IL-2 in combination with IFN (Rosenberg et al., 1989). Recent studies (Lee K.H. et al., 1989; Atzpodien et al., 1990b; Pichert et al., 1991) have confirmed that cytokine combination regimens with IL-2 doses in the range of 3 to 9 million IU m2 day and IFN-a are associated with manageable toxicity and are at least as effective as more toxic high-dose IL-2 regimens. Here we describe a regimen consisting of weekly sequential administration of i.m. IFN-a and varying IL-2 doses. Our primary aim was to verify if IL-2 doses lower than those used so far are still able to induce immunologic effects. Twelve patients with histologically confirmed cancer refractory to standard therapy or for which no effective standard therapy is available were included in the study (Table I). All patients had clinically measurable disease, no chemo/ hormonal/radio or immunotherapy within 4 weeks prior to study entry, no evidence of brain metastasis. The protocol

P. Di Stefano

Papers

Prognostic value of a novel circulating serum 90K antigen in breast cancer.

Carcinosarcoma and separate neuroendocrine malignant tumor of a malignancy promoter, the gastric stump.

Expression of HER-2/neu oncoprotein, DNA-ploidy and S-phase fraction in advanced ovarian cancer.

Elevated serum levels of a 90,000 daltons tumor-associated antigen in cancer and in infection by human immunodeficiency virus (HIV).

Immunological effects of alternative weekly interferon-alpha-2b and low dose interleukin-2 in patients with cancer.