Tumor-associated Autoantibodies Research Articles

Serum autoantibodies as biomarkers for early cancer detection

Autoantibodies against autologous tumor-associated antigens have been detected in the asymptomatic stage of cancer and can thus serve as biomarkers for early cancer diagnosis. Moreover, because autoantibodies are found in sera, they can be screened easily using a noninvasive approach. Consequently, many studies have been initiated to identify novel autoantibodies relevant to various cancer types. To facilitate autoantibody discovery, approaches that allow the simultaneous identification of multiple autoantibodies are preferred. Five such techniques--SEREX, phage display, protein microarray, SERPA and MAPPing--are discussed here. In the second part of this review, we discussed autoantibodies found in the five most common cancers (lung, breast, colorectal, stomach and liver). The discovery of panels of tumor-associated antigens and autoantibody signatures with high sensitivity and specificity would aid in the development of diagnostics, prognostics and therapeutics for cancer patients.

Identification of Tumor-associated Autoantigens for the Diagnosis of Colorectal Cancer in Serum Using High Density Protein Microarrays

There is a mounting evidence of the existence of autoantibodies associated to cancer progression. Antibodies are the target of choice for serum screening because of their stability and suitability for sensitive immunoassays. By using commercial protein microarrays containing 8000 human proteins, we examined 20 sera from colorectal cancer (CRC) patients and healthy subjects to identify autoantibody patterns and associated antigens. Forty-three proteins were differentially recognized by tumoral and reference sera (p value <0.04) in the protein microarrays. Five immunoreactive antigens, PIM1, MAPKAPK3, STK4, SRC, and FGFR4, showed the highest prevalence in cancer samples, whereas ACVR2B was more abundant in normal sera. Three of them, PIM1, MAPKAPK3, and ACVR2B, were used for further validation. A significant increase in the expression level of these antigens on CRC cell lines and colonic mucosa was confirmed by immunoblotting and immunohistochemistry on tissue microarrays. A diagnostic ELISA based on the combination of MAPKAPK3 and ACVR2B proteins yielded specificity and sensitivity values of 73.9 and 83.3% (area under the curve, 0.85), respectively, for CRC discrimination after using an independent sample set containing 94 sera representative of different stages of progression and control subjects. In summary, these studies confirmed the presence of specific autoantibodies for CRC and revealed new individual markers of disease (PIM1, MAPKAPK3, and ACVR2B) with the potential to diagnose CRC with higher specificity and sensitivity than previously reported serum biomarkers.

Aberrant tumor-associated antigen autoantibody profiles in healthy controls detected by multiplex bead-based immunoassay

There is an increasing amount of emphasis being placed on serological biomarkers as tools for early detection of various cancers. In addition to the tumor-related circulating antigens under current investigation, autoantibodies to tumor-associated antigens are emerging as alternative candidates due to their potential high sensitivity and specificity. Already a number of specific autoantibodies have been identified and several groups have reported on the ability of panels of autoantibodies to discriminate malignant from non-malignant conditions. In this investigation we evaluate tumor-associated antigen autoantibody profiles in a group of healthy individuals. We identify a subset of individuals that demonstrate high levels of autoantibody production across the spectrum of tumor-associated antigens tested. We conclude that this observation is a result of undefined non-malignant autoimmune stimulation. Our findings may be an indication of factors present in the general population that may confound multiplex autoantibody-based diagnostic tests by reducing assay specificity. Such factors will require further characterization and the development of adequate controls in order to improve the performance of diagnostic tests.

Detection of serum autoantlbodies for cyclinB1,p62,Koc,IMP1 and Survivin in the subjects with esophageal and gastric cardia carcinoma and precancerous lesions and their expressions in the esophageal and gastric cardia Cancer tissue

Objective To characterise the alterations of serum autoantibodies for cyclinB1,p62,Koc-IMP1 and survivin in the subjects with esophgeal and gastric cardia carcinoma and precancerous lesion and their expres-sions in the esophageal and gastric cardia cancer tissue.Methods Enzyme-linked immunoassay and tumor-associated antigen mini-array (consisting of five full-length recombinant proteins,including eyefinB1-p62-Koc,IMP1 and Survivin)were applied to determine the serum level of the autoantibodies of these antigens on 376 subjects with e-sephageal and gastric cardia carcinoma and precancerous lesions.At the same time,the expression of these antigens was detected by immunohistochemical method(ABC)on 13 patients with esophageal cancer and 16 with gastric car-dia cancer.Results All of the 5 antigens determined,the linear correlation Was observed for the detection frequency of cyclinB1,IMPI and p62 in esophageal carcinogenesis,and for p62 in gastric cardia multi-stage progression from normal to precancerous and cancerous lesions(P<0.05).The detection rale with single positive antoantibody im-munoreactivity for both esophageal and gastric cardia cancers were low.However.the positive detection mte for both esophageal and gastric cardia cancer increased apparently when the multiple positive markers were combined together for analysis,which increased tO 3～5 and 3～4 folds respectively.Furthermore,the difference in autoantibody immu-noreactive rate was significant with the lesion progressed from mild tO severe precancerous lesions and to cancer both in esophageal and gastric cardia cancers(P<0.05).The positive immunoreactions of the 5 antigens were detected in cancer tissues.The positive immunostaining rates for cyclinB1,Koc,IMP1 and Survivin both in esophageal and gastric cardia cancers were higher compared to their serllin positive rate of autoantibodies I P<0.05).Of the pa-tients with positive immunostaining in the two cancer tissues,the autoantibodies in the serum for the corresponding antigens could be detected in the same patient.Conclusion The production of the tumor-associated autoantibodies is related tO antigens.The screening rate through serum tumor-associated antigen mini-array for the patients with e-sophageal and gastric cardia carcinoma and precancerous lesions has been increased apparently with combined analy-sis of multiple autoantibodies than with single one. Key words: Esophageal carcinoma; Carcinonla of gastric cardia; Tumor-associated antigens; Au-toantibody

Profiling Tumor-Associated Autoantibodies for the Detection of Colon Cancer

The purpose of the present study was to screen the autoantibody signature of colon cancers to develop serum markers for colon cancer detection. A phage cDNA expression library of colon cancer was built. The library was sequentially screened by a pool of 10 colon cancer sera, goat antihuman IgG, and a pool of two healthy sera to identify phage-expressed antigens recognized by tumor-associated antibodies. The clones picked out by these screening were subjected to a training set with 24 colon cancer sera and 24 healthy sera. The antigen combination, which got the most satisfactory classification, was tested by an independent set of 24 colon cancer sera with equal number of sera from normal donors. The carcinoembryonic antigen (CEA) level of these sera was detected for the additional classification analysis with or without the antigen combination. A cDNA expression library consisting of 2 x 10(6) primary clones was prepared. After three turns of screening, 24 antigens recognized by tumor-associated antibodies were picked out for serum marker identification. The training set showed that a six-marker combination got the most satisfactory classification in a logistic regression model; leave-one-out validation achieved 91.7% sensitivity and 91.7% specificity. In a testing set with this marker panel, we correctly predicted 85% of the samples. Although according to CEA level alone, we correctly predicted 75% of the samples with 42% of cancer patients misclassified. When CEA was combined with the six markers, the sensitivity and specificity increased to 91.7% and 95.8%, respectively. The six antigen sequences in the phage display system are relatively short peptides. Only two of them showed homology to known protein sequences. Autoantibodies against phage-expressed antigens derived from colon cancer tissues could be used as serum markers for the detection of colon cancer.

Standard Treatments Induce Antigen-Specific Immune Responses in Prostate Cancer

Prostate tumors express antigens that are recognized by the immune system in a significant proportion of patients; however, little is known about the effect of standard treatments on tumor-specific immunity. Radiation therapy induces expression of inflammatory and immune-stimulatory molecules, and neoadjuvant hormone therapy causes prominent T-cell infiltration of prostate tumors. We therefore hypothesized that radiation therapy and hormone therapy may initiate tumor-specific immune responses. Pretreatment and posttreatment serum samples from 73 men with nonmetastatic prostate cancer and 50 cancer-free controls were evaluated by Western blotting and SEREX (serological identification of antigens by recombinant cDNA expression cloning) antigen arrays to examine whether autoantibody responses to tumor proteins arose during the course of standard treatment. Western blotting revealed the development of treatment-associated autoantibody responses in patients undergoing neoadjuvant hormone therapy (7 of 24, 29.2%), external beam radiation therapy (4 of 29, 13.8%), and brachytherapy (5 of 20, 25%), compared with 0 of 14 patients undergoing radical prostatectomy and 2 of 36 (5.6%) controls. Responses were seen within 4 to 9 months of initiation of treatment and were equally prevalent across different disease risk groups. Similarly, in the murine Shionogi tumor model, hormone therapy induced tumor-associated autoantibody responses in 5 of 10 animals. In four patients, SEREX immunoscreening of a prostate cancer cDNA expression library identified several antigens recognized by treatment-associated autoantibodies, including PARP1, ZNF707 + PTMA, CEP78, SDCCAG1, and ODF2. We show for the first time that standard treatments induce antigen-specific immune responses in prostate cancer patients. Thus, immunologic mechanisms may contribute to clinical outcomes after hormone and radiation therapy, an effect that could potentially be exploited as a practical, personalized form of immunotherapy.

Frequent appearance of autoantibodies against prohormone convertase 1/3 and neuroendocrine protein 7B2 in patients with nonfunctioning pituitary macroadenoma.

Among pituitary disorders having mass effect of the pituitary gland, nonfunctioning pituitary macroadenoma and lymphocytic hypophysitis are difficult to differentiate without histological examination. In order to efficiently distinguish lymphocytic hypophysitis and pituitary tumors, we studied the presence of autoantibodies against prohormone-processing enzymes, prohormone convertase (PC) 1/3, PC2, carboxypeptidase E (CPE), and PC2 regulatory protein, 7B2, by radioligand assay using recombinant human 35S-labeled protein in patients with clinically nonfunctioning pituitary macroadenoma, lymphocytic hypophysitis, and other pituitary diseases. The indexes for anti-PC1/3 antibodies (Ab) were significantly higher in patients with nonfunctioning pituitary macroadenoma than in patients with lymphocytic hypophysitis. Patients positive for either anti-PC1/3 or anti-7B2 Ab were significantly frequent among patients with nonfunctioning pituitary macroadenoma than in other pituitary diseases and healthy controls. None of the patients was positive for anti-PC2 Ab or anti-CPE Ab. These results suggest that autoantibodies against PC1/3 and 7B2 are novel tumor-associated autoantibodies and can be helpful in the diagnosis of clinically nonfunctioning pituitary macroadenoma.