Annals o f Clinical & Laboratory Science, vol. 30, no. 2, 2000 175

Elevated Serum Chromogranin A is Detectable in Patients with at Advanced Disease Stages

James T. Wu,1 Alan J. Erickson,1 Kuo-Chien Tsao,2 Tsu-Lan Wu,2 and Chien-Feng Sun2 1 Department of Pathology, University of Utah School of Medicine, and Associated Regional University Pathologists (ARUP), University of Utah Health Sciences Center, Salt Lake City, Utah 2 Department of Clinical Pathology, Chang Gung Memorial Hospital, Taipei, Taiwan

Abstract. Chromogranin A (CgA), a marker of neuroendocrine cells and an indicator for neuroendocrine differentiation, is associated with a poor prognosis when detected in tumor tissue, based on immunohistochemical techniques. We sought to determine whether it is possible to detect elevated serum CgA in patients with commonly occurring carcinomas of non-neuroendocrine origin. CgA was measured in both random and serial serum specimens, using a serum CgA assay developed in our laboratory. Elevated levels of serum CgA were detected in patients with of the prostate, breast, ovary, pancreas, and colon. Serum CgA levels in patients with all types of carcinoma appeared to parallel the changes of serum dominant tumor markers and were found in sera containing highly elevated tumor markers. Based on these preliminary findings, perhaps we should monitor CgA, in addition to the routinely used tumor markers, during the treatment of patients with carcinomas to determine if CgA is useful as a prognostic marker in carcinomas other than prostatic cancer.

Keywords: Chromogranin A, carcinoma antigens CA-15-3, CA-19-9, CA-125, (CEA), prostatic specific antigen (PSA)

Introduction CgA has been used to indicate neuroendocrine differentiation, which is a sign of poor prognosis. Serum chromogranin A (CgA) has been recognized as Neuroendocrine differentiation has recently been a valuable marker for , pheochromo- studied intensively in prostatic cancer [7], despite the cytoma, small cell lung carcinoma, and carcinoid fact that prostate tumors are not considered to be tumors—a group collectively known as the related to neuroendocrine tumors. Because of the neuroendocrine tumors [1,2]. Even though plasma relatively large number of neuroendocrine cells present and urine catecholamines and serotonin have been in the prostate and urethra [8], neuroendocrine traditionally used for the diagnosis and management differentiation is frequently observed in prostate of these tumors, CgA has been found to be more stable carcinomas, particularly in patients with distant and thus more easily applied clinically [3]. Serum CgA metastases (such as stage D2). Detection of CgA in has been reported to have a sensitivity of 91% and a prostate tumor tissue is also an indication of poor specificity of 100% for detection of prognosis. An increasing number of reports in the [4], Moreover, CgA may be a better marker than recent literature suggest that monitoring plasma or neuron-specific enolase in neuroendocrine tumors [5] serum CgA levels might reflect neuroendocrine and is considered by some as the preferred marker for differentiation of prostatic tumors [9,10]. neuroendocrine cells [6]. Other than prostatic cancer, most carcinomas have not been investigated to any great extent with respect to CgA. As with prostatic cancer, carcinomas that Address correspondence to James T. Wu, Ph.D., ARUP display neuroendocrine differentiation usually arise in Laboratories, 500 Chipeta Way, Salt Lake City, U T 84108; organs in which the normally contains tel 801 583 2787; fax 801 584 5207; e-mail [email protected]. neuro-endocrine cells. However, Bosman [11] recently 0091-7370/00/0200-0175 $0.75; © 2000 by the Association of Clinical Scientists, Inc. 176 Annals o f Clinical & Laboratory Science noted that neuroendocrine differentiation can occur Modified serum CgA assay. The enzyme immunoassay in carcinomas that lack neuroendocrine cells in their used in this study was a slightly modified version of normal epithelial counterparts; such carcinomas our previous serum CgA assay [13]. The modified include mucinous cystadenocarcinoma of the ovary, assay has a wider concentration range and reduced risk ovarian teratoma, and . Most of “hook” effects. In the modified assay, 150 |ol (instead of these observations have been based on immunohisto- of 100 |ol) of polyclonal rabbit anti-human CgA (4 chemical techniques. Since an unfavorable prognosis |ig/ml) is coated onto each well, and less serum (only has frequently been found to be associated with 20 (jl) is added. Only one incubation (4 hr) is per­ neuroendocrine differentiation in epithelial tumors formed. The serum sample (20 |il), the detecting anti­ [6,8], and since positive correlation has been reported body (50 |il), and the BSA-PBS reagent (80 JjJ) are between the serum levels of CgA and the number of incubated together in the antibody-coated well. The CgA-staining cells in carcinoma of the prostate [12], BSA-PBS reagent contains phosphate buffer (pH 7.2, we were interested to know whether serum CgA would 10 mmol/L) and bovine serum albumin (10 g/L). Sera be a prognostic marker in those commonly occurring with highly elevated CgA levels from patients with renal carcinomas. We suspected that, in addition to being insufficiency were pooled to prepare the calibrator. useful for prognosis, detection of elevated CgA might indicate the proliferation of neuroendocrine cells in Results the tumor. In addition to targeting epithelial tumor cells for treatment, therapeutic strategies should take CgA in random specimens. Elevated CgA was detected into consideration the presence or absence of neuro­ in random serum specimens from patients with endocrine cells. prostatic, breast, ovarian, colon, and pancreatic In this study, we measured CgA levels in both malignancies (Fig. 1). Weak correlations between the random and serial serum specimens that had been collected from patients with various carcinomas, taking y ** 0.2977x + 151.72 advantage of a sensitive serum CgA immunoassay that has been developed in our laboratory. Elevated serum CgA levels were detected in patients with carcinomas of the prostate, breast, ovary, pancreas, and colon, and appeared to be associated with serum specimens that contained highly elevated tumor markers. This suggests that elevated serum CgA usually appears at advanced stages of disease progression.

Materials and Methods

Polyclonal rabbit anti-human CgA antibody and HRP- 1 0 1

II 6 conjugated monoclonal mouse anti-human CgA N = 18 1200 Z £ 1000 antibody were both purchased from Dako (Carpintería, M0‘ o .___ < CA). These antibodies were against the C-terminal, 400 290 20 kDa fragment of the CgA molecule. Immulon-4 0

Van?^ ------.— u - 0 9 8 , *\ Removawell strips were obtained from Dynatech CA-19-9 (U/mL) CEA (ng/mL) Laboratories (Chantilly, VA). K-blue substrate-TMB reagent was obtained from Neogen Corp. (Lexington, KY). Assays were performed on random and serial serum specimens that had been sent to ARUP Fig. 1. Correlation of serum CgA with other tumor markers laboratories for determination of tumor markers. Some in random serum specimens from patients with various of the sera had been frozen at -70°C for a few years. carcinomas. Chromogranin A levels in serums o f carcinoma patients 177 serum CgA levels and tumor marker levels appeared (Fig. 2). To compare the serum CgA levels and the to exist. It should be noted that prostatic specific levels of dominant tumor markers, the data were antigen (PSA), CA-15-3, CA-125, CA-19-9, and normalized by dividing the observed levels by the upper carcinoembryonic antigen (CEA) are dominant tumor limits of their respective normal ranges. After such markers of the prostate, breast, ovary, pancreas, and adjustment, values > 1 indicated an abnormal or colon, respectively. Extremely elevated serum CgA elevated serum level for the marker; values < 1 indicated levels (eg, >500 ng/ml) were only detectable in sera that the serum level was within the normal range of containing highly elevated serum tumor markers, con-centrations. In each of the cases shown in Fig. 2, suggesting that the elevation of serum CgA is more serum CgA became elevated at a later stage of the likely at advanced stages of these malignancies. malignant disease or at a time when the dominant tumor markers were already greatly increased. In the CgA in serial specimens. The appearance of elevated patients with pancreatic, prostatic, or , serum CgA levels at advanced stages of carcinoma serum levels of CgA and their predominant tumor progression was corroborated by levels of serum CgA markers changed in parallel with each other, whereas in serial specimens from individual patients with in the patients with colon or , concordance various carcinomas. Elevated serum CgA was was less evident. associated with dominant tumor markers in carcinomas The degree and frequency of serum CgA elevation varied among the various carcinomas. Breast cancer patients showed the lowest frequency of serum CgA Colon Cancer (CEA) elevation; ovarian cancer patients exhibited the highest

■A * frequency and highest levels of CgA elevation (Figs. 1 «• Q Tumor marker & 2). Only 1 of 5 breast cancer patients showed elevated serum CgA, but 9 of 9 ovarian cancer patients showed elevated serum CgA. Extremely elevated levels of CgA were detected in sera from ovarian cancer patients whose CA-125 levels were only moderately above the upper limit of the normal range.

Breast tumor cytosol. As shown in Fig. 3, CgA was

Negative ER & PgR Positive ER & PgR (339) j JI467) —(279) » N=78 N=16 50% 44%

• •

■■ •

• M > Fig. 2. Correlations of serum CgA levels with other tumor Breast Tumor Cytosol markers in serial serum specimens from individual patients with various carcinomas. Tumor marker levels were Fig. 3. CgA levels in human breast tumor cytosols, normalized by dividing each result by the upper limit of the categorized as ER- & PgR-negative or ER- & PgR-positive. respective normal range (ie, CgA: 90 ng/ml; CEA: 2.5 ng/ CgA was detected in 50% of the receptor-negative and 44% ml; CA-19-9: 37 U/ml; PSA: 4 ng/ml; CA-125: 35 U/ml; of the receptor-positive cytosols. The highest CgA levels CA 15-3: 25 U/ml). (ng/ml) in tumor cytosol samples are shown in parentheses. 178 Annals o f Clinical & Laboratory Science detected in several specimens of human breast tumor A in , primary hyperpara­ cytosol that had been retained after estrogen receptor thyroidism and pituitary adenoma in comparison with (ER) and progesterone receptor (PgR) measurements. catecholamine, parathyroid hormone and pituitary CgA was detected in 50% (39/78) of tumor cytosols hormones. EndocrJ 1997;44:319-327. 2. Stridsberg M, Husebye ES. Chromogranin A and that were ER- and PgR-negative, and in 44% (7/16) chromogranin B are sensitive circulating markers for of tumor cytosols that were ER- and PgR-positive. The pheochromocytoma. Eur J Endocrinol 1997; 136: results did not indicate that the presence of detectable 67-73. CgA was associated with positive or negative expression 3. Nobels FR, Kwekkeboom DJ, Bouillon R, et al. of ER and PgR in breast tumor cytosols. 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