Clinica Chimica Acra. 210 (1992) 5-12 %I 1992 Elsevier Science Publishers B.V. All rights reserved. 0009-8981/92/$05.00
CCA 05356
Arginase, a new marker of mammary carcinoma B. &rausa, Ivana cepelak” and G. Festab ‘Institute of Medical Biochemisrry. Faculty of Pharmacy and Biochemistry. University of Zagreb. Zagreb and ‘General Hospirul, Doboj (Croutia)
(Received 29 April 1991; revision received 14 March 1992; accepted 27 April 1992)
Key words: Arginase; Breast carcinoma: Tumour markers
Summary
Activities of arginase, alanine aminotransferase, aspartate aminotransferase and alkaline phosphatase were determined in sera obtained in a group of healthy women, women with verified carcinoma of the breast, benign mastopathy, a group of patients with carcinoma of various organs and a group of patients with acute viral hepatitis. Preoperative values of serum arginase activity in patients with breast carcinoma were up to 4-fold those found in healthy women. Sensitivity of the test was 86%. After the surgery, the activity decreased abruptly during the first week and normalised within 15-30 days. In benign diseases of the breast, the activity of arginase was normal. Serum arginase activity is raised in both benign and malignant liver diseases, however, the quotients alanine aminotransferase/arginase, aspartate aminotransferasejarginase and alkaline phosphatase/arginase differ significantly. Thus, use of alanine aminotransferaselarginase quotient implies a high degree of confidence in differentiating between increased arginase activity in mammary carcinoma (alanine aminotransferase/arginase = 0.572 f 0.278) and high arginase activity in hepatitis (alanine aminotransferase/arginase = 12.226 f 1.822).
Introduction
The diagnosis of mammary carcinoma is based on a number of procedures including palpation, mammography, thermography, pneumocystography, galactography, xerography and ultrasound. In addition, a series of tumour markers that are Correspondence lo: Dr. lvana cepelak, Institute of Medical Biochemistry, Faculty of Pharmacy and Biochemistry, Domagojeva 2, 41000, Zagreb, Croatia.
6
not specific for mammary carcinoma may be measured; their concentration has been shown to increase also in malignant tumour of the breast as well. These markers include: carcinoembryonic antigen (CEA), the carcinoma antigens Ca 15-3 and Ca-549, mutinous carcinoma associated antigen (MCA) and estradiol or progesterone receptors [l-4]. Arginase (L-arginine amidinohydrolase (ARG); EC 3.5.3.1) is a hydrolase acting upon C-N bonds. The enzymes is mostly found in the liver, where it catalyzes the final reaction in the synthesis of urea, i.e. hydrolysis of arginine into ornithine and urea [5,6]. Raised activities ARG in serum are found in hepatic diseases. However, minor activities of ARG can also be observed in other tissues (kidney, brain, lung, blood cells, etc.) and in mammary glands [7-91. There is a hypotesis concerning the role of ARG in mammary glands, proposing that it is involved in the synthesis of proline: this is supported by the observation of raised activity in the breast during lactation. The presence of ARG in the breast and malignant tissue and the existence of a specific mammary ARG isoenzyme [lo] urged us to embark upon the study of this enzyme activity in serum from patients with carcinoma of the breast. Material and Methods ARG activity was tested in serum of 165 women and 30 men, divided into live groups. Group 1 consisted of 30 healthy women aged 20-50 years. Group 2 consisted of 70 women with verified carcinoma of the breast. In this group, the activity of ARG in serum was determined just bkfore the surgery and was followed postoperatively at l-month intervals. Group 3 comprised of 40 women with benign mastopathy, whereas group 4 consisted of 37 cases (17 females and 20 males) of malignant tumours of various organs other than the breast. Group 5 comprised of 18 patients (8 females and 10 males) with acute viral hepatitis. The diagnosis for the particular disease was established through the standard clinical procedure, respectively. Serum ARG activity was determined by a method described elsewhere [l 11, the serum being previous dialysed for 4 h against 0.154 mol/l NaCl containing 10 mol/l MnCl*, in order to remove urea. Besides ARG, the activities of aspartate aminotransferase (AST), alanine aminotransferase (ALT) and alkaline phosphatase (ALP) were also determined in all sera using Commercial Kits (Abbott Laboratories, Chicago, USA) on system Abba 100. In the evaluation of the diagnostic efficiency of the proposed parameters the multivariate descriminant analysis was performed
u21.
Reference ARG values as determined in the group of healthy women were 14.53 f 3.56 units/l and showed a normal distribution. These values are almost 2-fold those previously reported [ 11- 141. In mammary carcinoma, raised activities of ARG in serum were found preoperatively in 60 out of 70 patients examined (Fig. 1). Thus the diagnostic sensitivity of ARG in serum as a marker of mammary carcinoma was found to be 86%.
7
92
-
88
-
84
-
80
-
16
-
12
-
68
-
. . . .
.
64 -
--r*.. : . it: . :..
56 _J . 3
5248 -
8 e
44 -
1.:
40 -
tfi
36
.
32 -
:*
28 24. ---
ii!
:,"12 - 7
at* __d_
8.
. . : . . .
. .
60 -
lt .
+I+ :.w __J_
.
b’
‘it . . : “1 l*
.
.
f” .* .
. . ---.* . .
. . --tt-.* . . . . . . .
_*_c_9. .
+ l ** ‘*-7-
!I’:
l
4-
I HEALTHY WOMEN
MASTOPATH‘
3REAST :ANCER
ANCER OF VARIOUS ORGANS EXCEPT BREAST
ACUTE VIRAL HEPATITIS
Fig. 1. Serum ARG activity in all examined groups (solid line = mean; dotted line = S.D.).
In these patients, ARG activity ranged from 23 to 92 units/l, mean being 41 units/l. After surgery, the activity of ARG in serum decreased abruptly during the first week and became normal within 15-30 days (Fig. 2). The curve of postoperative activity may have a prognostic value. The enzyme activity in serum usually decreased, with a possible intermittent increase during irradiation (Fig. 3A). However, persistently high activities or further increases, as recorded in several patients, seem to point to metastases or incomplete removal of the primary tumour (Fig. 3B); this could therefore indicate poor prognosis. Figure 1 shows that normal ARG activity was found in 32 cases of benign breast disease, whereas in the remaining 8 patients the activity was moderately raised, ranging from 23 to 33 units/l. These 8 patients, primarily diagnosed as mastopathy, were further followed up and 2-12 months after the initial finding of increased ARG
. l
.
.
. . i_-_
-_
/‘i
x \ : ’\
. -s 7 I
t :
i
/
m
2 .
;-_
-_---
i
.‘\,
// I
.
.
L--I HEALTHY WOMEN
-
BEFORE SURGERY
I
I
---LL 5 DAYS
15 FROM
I
30
SURGERY
Fig. 2. The time course of ARG activities before and after surgery (solid line = mean; dotted line = SD.).
activity, carcinoma of the breast was detected in 7 of them and they were operated on. It should be noted that all these patients had very low quotients of aminotransferases or ALP and ARG (Table I). In patients with malignant tumours of various localisations other than the breast, serum ARG activity was variable. Occasionally quite high values were observed and sometimes values within the reference range were recorded (Fig. 1). A more thorough analysis of this group showed that activity of ARG was raised only in cases of malignant tumours of hepatobiliary tract or in liver metastases, whereas in others it was generally normal. However, the quotients of ALT/ARG, AST/ARG and ALP/ARG in patients with breast carcinoma were significantly different from the quotients formed in benign and malignant diseases of liver (Table II). In patients with malignant tumours of hepatobiliary tract, a high ARG activity
9
A
SURGERY
,
60 _.I 3
50
g
30
RADIOTHERAPY
LO
20
----
_
__--
I
26
35
42 DAYS
RADIOTHERAPY
Fig. 3. (A) Typical activity of ARG in serum during recovery period. (B) Activity of ARG in a patient with the bad prognosis.
TABLE I Activities of ARG, AST, ALT and ALP (units/I) and their quotients in the group of patients with diagnosis of mastopathy who later on developed carcinoma of mammary gland. Patients
1 2 3 4 5 6 7 8
ARG
33.4 23.4 29.5 27.1 26.3 25.4 30.2 28.5
AST
15 15 17 I3 22 I4 I6 I4
ALT
13 18 20 II 31 I8 21 I2
ALP
26 24 14 27 23 21 I9 20
Quotient ASTIARG
ALTIARG
ALPIARG
0.449 0.641 0.576 0.479 0.836 0.551 0.530 0.491
0.389 0.769 0.678 0.406 I.178 0.708 0.695 0.421
0.778 1.026 0.476 0.996 0.874 0.827 0.629 0.701
IO
TABLE II ASTIARG, ALTiARG and ALP/ARG quotients (mean f SD.) in the examined groups of patients and normal subjects. Statistical analysis as made using r-test. We compared each group with breast carcinoma group: *P < 0.01; **P < 0.001 ALTIARG
ALPIARG
Subjects
ASTIARG
Healthy women (n = 30) Breast carcinoma (n = 70) Benign mastopathy (n = 40) Carcinoma of various organs except the liver and the breast (n = 22) Liver metastasis and carcinoma (n = 15) Acute viral hepatitis
0.976 f 0.337*
1.049 l 0.307*
1.502 f 0.459*
0.488 f 0.181
0.572 f 0.287
0.671 ziz0.279
0.882 f. 0.371*
0.993 zt 0.448*
1.276 f 0.433*
0.775 f 0.212
0.982 f 0.360*
1.442 +z 0.378*
7.219 i 1.603**
13.089 f 2.418**
3.115 f 0.685**
7.445 f 1.310**
12.226 zt 1.822**
2.286 f 0.399**
(n = 18)
indicated the enzyme release from ARG-rich liver cells, which also leads to increased serum activity of ARG in all cases of acute hepatitis (Fig. 1). As it was shown by multiva~a~ di~riminating analysis dete~ination of AL?“, AST or ALP together with ARG activity offers a very good discrimination between breast carcinoma and liver diseases (the function being 0.73193, 0.32131 and 0.10527, respectively, with centroids for breast carcinoma -2.0099 and for benign or malignant hepatobiliary diseases being +4.2636) Discussion
Our reference values for the activity of ARG in serum were markedly higher than most values found in literature [ 11,13,14]. The reason for the increased activity found is connected with the elimination of urea from the serum samples. The dialysis of all samples was performed prior to enzymatic analysis. It is known that urea when present in excess inhibits ARG. That could be demonstrated by low ARG activity in patients with uremia [ 151. Our results showed serum ARG to be a sensitive marker of mammary carcinoma. This increase in serum ARG activity might probably be attributed to the enzyme release from the mammary tissue affected by the tumour, while in case of metastases ARG also might originate from the malignant cells themselves. Serum activity decreased abruptly during the first week after the surgery, which is supported by data on a short ARG tlj2 [16]. Subsequent slowing down of the decrease or even a
11
transient increase in the activity most probably resulted from irradiation applied postoperatively. Although the number of patients was too small for any definite conclusions to be made, quite interesting was the observation that in 7 out of 8 patients considered as mastopathies ARG had been increased, usually up to 30 units/l, as early as a year before the diagnosis of mammary carcinoma. This appears to indicate that increase in serum ARG activity could be an early sign of mammary carcinoma and useful test for its early detection. The cause of such an early increase in the activity of ARG is still unclear. The cause might possibly be searched for in hormonal changes and the possibility of ARG induction. Some cortocosteroids are known to induce the synthesis of ARG [17j. Further prospective studies in this respect appear to be necessary. Besides sensitivity, a tumour marker must be diagnostically specific to be fully useful. Specificity of ARG as a marker of breast carcinoma is compromised by the fact that it is generally increased in both benign and malignant hepatic diseases, Therefore, it quite justified to expect that further studies and elaboration of the methods of detection of the breast isoenzymes would certainly improve the specificity of ARG as a marker of mammary carcinoma. However, we are inclined to believe that the ARG activity increase due to mammary carcinoma could be quite certainly differentiated from the ARG activity increase induced by liver diseases, if the ARG activity determination be supplemented by the assessment of aminotransferases and ALP. In breast carcinoma, the activities of AST, ALT and ALP are normal, whereas in liver diseases they are always elevated, thus the ASTIARG, ALT/ARG and ALPlARG quotients being significantly different (Table II). Accordingly, an increased serum activity of ARG, along with ALT/ARG, AST/ARG and ALP/ARG quotients below mean f 2 S.D., 1.15, 0.85 and 1.23, respectively, appears to be a very specific indicator of breast carcinoma. In practice, we propose only ALT to be determined along with ARG, because differences in the ALT/ARG quotients are greatest and gives a 100% specificity of the test.
This study was supported by the Self-managed Community Scientific Research of the Republic of Croatia.
of Interest V for
1 Duffy MJ, Sherry F. Studies on CA 15-3, a new marker in breast dancer. Clin Sci 1986;71(suppl. 15):28 pp. 2 Chan WD, Beveridge AR, Bruzek DJ, et al. Monitoring breast cancer with CA 549. Clin Chem 1988;34:2000-2004. 3 Duffy MJ. New cancer markers. Ann Clin B&hem 1989;26:379-387. 4 Duffy MJ. Biochemical markers as prognostic indicies in breast cancer. Clin Chem 1990;36:188-191. 5 Masaki Ikemato, Masayoshi Tabata, Takashi Murachi, Masayuki Totani. ~ri~cation and properties of human erytrocyte arginase. Ann Clin Biochem 1989;26:.547-553. 6 Colombo JP, Konarska L. Arginase. In: Bergmeyer HU, eds. Methods of enzymatic analysis, Vol. IV. Base& Weinheim, Deertield Beach: Verlag Chemie, 1984;285-294.
12 7 8 9 10
II 12 13 14 15 16
17
Mezl VA, Knox WE. Metabolism of arginine in lactating rat mammary gland. Biochem J 1977;164:105-113. Skrzypek-Osiecka Iwona, Robin Yvonne, Porembska Zofia. Purification of rat kidney arginases A, and A, and their subcellular distribution. Acta Biochim Polon 1983;30:82-92. Straus B, BorEiC 0. Inhibitory action of some aminoacids on arginase from human liver, kidney, mammary gland and erytrocytes. Acta Pharm Jugosl 1976;26:149- 153. BorCiC0, Straus B. Separation of arginase from human tissues by agar gel electrophoresis. J Clin Chem Clin Biochem 3976;14:533-535. Jergovid I, ZuiiC Ivana, FiSer-Herman Marijana, Straus B. A simple method for serum arginase determination Clin Chim Acta 1970;30:765-774. Coley WW, Lohnes PL. Multivariate date analysis. New York: John Wiley and Sons, 1971. Zopf PW. A semiautomated method for plasma arginase. Clin Chim Acta 1969;26:547-554. Dargel VR. Verbesserte Methode zur Bestimmung der Serumarginase-aktivitat. Z Klin Chem 1966;4:36-37. Nishibe H. Ultramicromethod for the determination of human arginase in the presence of urea. Clin Chim Acta 1976;71:413-418. Visco C, Benassi CA, Veronese FM, Miglioli PA. Purification, modification, physico-chemical and pharmacokinetic characterization of arginase. An enzyme of potential use in therapy. II farmaco edizione Scientifica 1987;42:449-559. Aebi H. Coordinated changes in enzymes of the ornithine cycle and response to dietary conditions. In: Grisolia A, Baguena R, Mayer F, eds. The urea cycle. New York: John Wiley & Sons, 1976;275-296.
CCA 05356
Arginase, a new marker of mammary carcinoma B. &rausa, Ivana cepelak” and G. Festab ‘Institute of Medical Biochemisrry. Faculty of Pharmacy and Biochemistry. University of Zagreb. Zagreb and ‘General Hospirul, Doboj (Croutia)
(Received 29 April 1991; revision received 14 March 1992; accepted 27 April 1992)
Key words: Arginase; Breast carcinoma: Tumour markers
Summary
Activities of arginase, alanine aminotransferase, aspartate aminotransferase and alkaline phosphatase were determined in sera obtained in a group of healthy women, women with verified carcinoma of the breast, benign mastopathy, a group of patients with carcinoma of various organs and a group of patients with acute viral hepatitis. Preoperative values of serum arginase activity in patients with breast carcinoma were up to 4-fold those found in healthy women. Sensitivity of the test was 86%. After the surgery, the activity decreased abruptly during the first week and normalised within 15-30 days. In benign diseases of the breast, the activity of arginase was normal. Serum arginase activity is raised in both benign and malignant liver diseases, however, the quotients alanine aminotransferase/arginase, aspartate aminotransferasejarginase and alkaline phosphatase/arginase differ significantly. Thus, use of alanine aminotransferaselarginase quotient implies a high degree of confidence in differentiating between increased arginase activity in mammary carcinoma (alanine aminotransferase/arginase = 0.572 f 0.278) and high arginase activity in hepatitis (alanine aminotransferase/arginase = 12.226 f 1.822).
Introduction
The diagnosis of mammary carcinoma is based on a number of procedures including palpation, mammography, thermography, pneumocystography, galactography, xerography and ultrasound. In addition, a series of tumour markers that are Correspondence lo: Dr. lvana cepelak, Institute of Medical Biochemistry, Faculty of Pharmacy and Biochemistry, Domagojeva 2, 41000, Zagreb, Croatia.
6
not specific for mammary carcinoma may be measured; their concentration has been shown to increase also in malignant tumour of the breast as well. These markers include: carcinoembryonic antigen (CEA), the carcinoma antigens Ca 15-3 and Ca-549, mutinous carcinoma associated antigen (MCA) and estradiol or progesterone receptors [l-4]. Arginase (L-arginine amidinohydrolase (ARG); EC 3.5.3.1) is a hydrolase acting upon C-N bonds. The enzymes is mostly found in the liver, where it catalyzes the final reaction in the synthesis of urea, i.e. hydrolysis of arginine into ornithine and urea [5,6]. Raised activities ARG in serum are found in hepatic diseases. However, minor activities of ARG can also be observed in other tissues (kidney, brain, lung, blood cells, etc.) and in mammary glands [7-91. There is a hypotesis concerning the role of ARG in mammary glands, proposing that it is involved in the synthesis of proline: this is supported by the observation of raised activity in the breast during lactation. The presence of ARG in the breast and malignant tissue and the existence of a specific mammary ARG isoenzyme [lo] urged us to embark upon the study of this enzyme activity in serum from patients with carcinoma of the breast. Material and Methods ARG activity was tested in serum of 165 women and 30 men, divided into live groups. Group 1 consisted of 30 healthy women aged 20-50 years. Group 2 consisted of 70 women with verified carcinoma of the breast. In this group, the activity of ARG in serum was determined just bkfore the surgery and was followed postoperatively at l-month intervals. Group 3 comprised of 40 women with benign mastopathy, whereas group 4 consisted of 37 cases (17 females and 20 males) of malignant tumours of various organs other than the breast. Group 5 comprised of 18 patients (8 females and 10 males) with acute viral hepatitis. The diagnosis for the particular disease was established through the standard clinical procedure, respectively. Serum ARG activity was determined by a method described elsewhere [l 11, the serum being previous dialysed for 4 h against 0.154 mol/l NaCl containing 10 mol/l MnCl*, in order to remove urea. Besides ARG, the activities of aspartate aminotransferase (AST), alanine aminotransferase (ALT) and alkaline phosphatase (ALP) were also determined in all sera using Commercial Kits (Abbott Laboratories, Chicago, USA) on system Abba 100. In the evaluation of the diagnostic efficiency of the proposed parameters the multivariate descriminant analysis was performed
u21.
Reference ARG values as determined in the group of healthy women were 14.53 f 3.56 units/l and showed a normal distribution. These values are almost 2-fold those previously reported [ 11- 141. In mammary carcinoma, raised activities of ARG in serum were found preoperatively in 60 out of 70 patients examined (Fig. 1). Thus the diagnostic sensitivity of ARG in serum as a marker of mammary carcinoma was found to be 86%.
7
92
-
88
-
84
-
80
-
16
-
12
-
68
-
. . . .
.
64 -
--r*.. : . it: . :..
56 _J . 3
5248 -
8 e
44 -
1.:
40 -
tfi
36
.
32 -
:*
28 24. ---
ii!
:,"12 - 7
at* __d_
8.
. . : . . .
. .
60 -
lt .
+I+ :.w __J_
.
b’
‘it . . : “1 l*
.
.
f” .* .
. . ---.* . .
. . --tt-.* . . . . . . .
_*_c_9. .
+ l ** ‘*-7-
!I’:
l
4-
I HEALTHY WOMEN
MASTOPATH‘
3REAST :ANCER
ANCER OF VARIOUS ORGANS EXCEPT BREAST
ACUTE VIRAL HEPATITIS
Fig. 1. Serum ARG activity in all examined groups (solid line = mean; dotted line = S.D.).
In these patients, ARG activity ranged from 23 to 92 units/l, mean being 41 units/l. After surgery, the activity of ARG in serum decreased abruptly during the first week and became normal within 15-30 days (Fig. 2). The curve of postoperative activity may have a prognostic value. The enzyme activity in serum usually decreased, with a possible intermittent increase during irradiation (Fig. 3A). However, persistently high activities or further increases, as recorded in several patients, seem to point to metastases or incomplete removal of the primary tumour (Fig. 3B); this could therefore indicate poor prognosis. Figure 1 shows that normal ARG activity was found in 32 cases of benign breast disease, whereas in the remaining 8 patients the activity was moderately raised, ranging from 23 to 33 units/l. These 8 patients, primarily diagnosed as mastopathy, were further followed up and 2-12 months after the initial finding of increased ARG
. l
.
.
. . i_-_
-_
/‘i
x \ : ’\
. -s 7 I
t :
i
/
m
2 .
;-_
-_---
i
.‘\,
// I
.
.
L--I HEALTHY WOMEN
-
BEFORE SURGERY
I
I
---LL 5 DAYS
15 FROM
I
30
SURGERY
Fig. 2. The time course of ARG activities before and after surgery (solid line = mean; dotted line = SD.).
activity, carcinoma of the breast was detected in 7 of them and they were operated on. It should be noted that all these patients had very low quotients of aminotransferases or ALP and ARG (Table I). In patients with malignant tumours of various localisations other than the breast, serum ARG activity was variable. Occasionally quite high values were observed and sometimes values within the reference range were recorded (Fig. 1). A more thorough analysis of this group showed that activity of ARG was raised only in cases of malignant tumours of hepatobiliary tract or in liver metastases, whereas in others it was generally normal. However, the quotients of ALT/ARG, AST/ARG and ALP/ARG in patients with breast carcinoma were significantly different from the quotients formed in benign and malignant diseases of liver (Table II). In patients with malignant tumours of hepatobiliary tract, a high ARG activity
9
A
SURGERY
,
60 _.I 3
50
g
30
RADIOTHERAPY
LO
20
----
_
__--
I
26
35
42 DAYS
RADIOTHERAPY
Fig. 3. (A) Typical activity of ARG in serum during recovery period. (B) Activity of ARG in a patient with the bad prognosis.
TABLE I Activities of ARG, AST, ALT and ALP (units/I) and their quotients in the group of patients with diagnosis of mastopathy who later on developed carcinoma of mammary gland. Patients
1 2 3 4 5 6 7 8
ARG
33.4 23.4 29.5 27.1 26.3 25.4 30.2 28.5
AST
15 15 17 I3 22 I4 I6 I4
ALT
13 18 20 II 31 I8 21 I2
ALP
26 24 14 27 23 21 I9 20
Quotient ASTIARG
ALTIARG
ALPIARG
0.449 0.641 0.576 0.479 0.836 0.551 0.530 0.491
0.389 0.769 0.678 0.406 I.178 0.708 0.695 0.421
0.778 1.026 0.476 0.996 0.874 0.827 0.629 0.701
IO
TABLE II ASTIARG, ALTiARG and ALP/ARG quotients (mean f SD.) in the examined groups of patients and normal subjects. Statistical analysis as made using r-test. We compared each group with breast carcinoma group: *P < 0.01; **P < 0.001 ALTIARG
ALPIARG
Subjects
ASTIARG
Healthy women (n = 30) Breast carcinoma (n = 70) Benign mastopathy (n = 40) Carcinoma of various organs except the liver and the breast (n = 22) Liver metastasis and carcinoma (n = 15) Acute viral hepatitis
0.976 f 0.337*
1.049 l 0.307*
1.502 f 0.459*
0.488 f 0.181
0.572 f 0.287
0.671 ziz0.279
0.882 f. 0.371*
0.993 zt 0.448*
1.276 f 0.433*
0.775 f 0.212
0.982 f 0.360*
1.442 +z 0.378*
7.219 i 1.603**
13.089 f 2.418**
3.115 f 0.685**
7.445 f 1.310**
12.226 zt 1.822**
2.286 f 0.399**
(n = 18)
indicated the enzyme release from ARG-rich liver cells, which also leads to increased serum activity of ARG in all cases of acute hepatitis (Fig. 1). As it was shown by multiva~a~ di~riminating analysis dete~ination of AL?“, AST or ALP together with ARG activity offers a very good discrimination between breast carcinoma and liver diseases (the function being 0.73193, 0.32131 and 0.10527, respectively, with centroids for breast carcinoma -2.0099 and for benign or malignant hepatobiliary diseases being +4.2636) Discussion
Our reference values for the activity of ARG in serum were markedly higher than most values found in literature [ 11,13,14]. The reason for the increased activity found is connected with the elimination of urea from the serum samples. The dialysis of all samples was performed prior to enzymatic analysis. It is known that urea when present in excess inhibits ARG. That could be demonstrated by low ARG activity in patients with uremia [ 151. Our results showed serum ARG to be a sensitive marker of mammary carcinoma. This increase in serum ARG activity might probably be attributed to the enzyme release from the mammary tissue affected by the tumour, while in case of metastases ARG also might originate from the malignant cells themselves. Serum activity decreased abruptly during the first week after the surgery, which is supported by data on a short ARG tlj2 [16]. Subsequent slowing down of the decrease or even a
11
transient increase in the activity most probably resulted from irradiation applied postoperatively. Although the number of patients was too small for any definite conclusions to be made, quite interesting was the observation that in 7 out of 8 patients considered as mastopathies ARG had been increased, usually up to 30 units/l, as early as a year before the diagnosis of mammary carcinoma. This appears to indicate that increase in serum ARG activity could be an early sign of mammary carcinoma and useful test for its early detection. The cause of such an early increase in the activity of ARG is still unclear. The cause might possibly be searched for in hormonal changes and the possibility of ARG induction. Some cortocosteroids are known to induce the synthesis of ARG [17j. Further prospective studies in this respect appear to be necessary. Besides sensitivity, a tumour marker must be diagnostically specific to be fully useful. Specificity of ARG as a marker of breast carcinoma is compromised by the fact that it is generally increased in both benign and malignant hepatic diseases, Therefore, it quite justified to expect that further studies and elaboration of the methods of detection of the breast isoenzymes would certainly improve the specificity of ARG as a marker of mammary carcinoma. However, we are inclined to believe that the ARG activity increase due to mammary carcinoma could be quite certainly differentiated from the ARG activity increase induced by liver diseases, if the ARG activity determination be supplemented by the assessment of aminotransferases and ALP. In breast carcinoma, the activities of AST, ALT and ALP are normal, whereas in liver diseases they are always elevated, thus the ASTIARG, ALT/ARG and ALPlARG quotients being significantly different (Table II). Accordingly, an increased serum activity of ARG, along with ALT/ARG, AST/ARG and ALP/ARG quotients below mean f 2 S.D., 1.15, 0.85 and 1.23, respectively, appears to be a very specific indicator of breast carcinoma. In practice, we propose only ALT to be determined along with ARG, because differences in the ALT/ARG quotients are greatest and gives a 100% specificity of the test.
This study was supported by the Self-managed Community Scientific Research of the Republic of Croatia.
of Interest V for
1 Duffy MJ, Sherry F. Studies on CA 15-3, a new marker in breast dancer. Clin Sci 1986;71(suppl. 15):28 pp. 2 Chan WD, Beveridge AR, Bruzek DJ, et al. Monitoring breast cancer with CA 549. Clin Chem 1988;34:2000-2004. 3 Duffy MJ. New cancer markers. Ann Clin B&hem 1989;26:379-387. 4 Duffy MJ. Biochemical markers as prognostic indicies in breast cancer. Clin Chem 1990;36:188-191. 5 Masaki Ikemato, Masayoshi Tabata, Takashi Murachi, Masayuki Totani. ~ri~cation and properties of human erytrocyte arginase. Ann Clin Biochem 1989;26:.547-553. 6 Colombo JP, Konarska L. Arginase. In: Bergmeyer HU, eds. Methods of enzymatic analysis, Vol. IV. Base& Weinheim, Deertield Beach: Verlag Chemie, 1984;285-294.
12 7 8 9 10
II 12 13 14 15 16
17
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