Shin-ichi Yamashita

Overexpression of group II phospholipase A2 in human breast cancer tissues is closely associated with their malignant potency

Membrane-associated phospholipase A2 (M-PLA2) is an enzyme that hydrolyses the sn-2 fatty acyl ester bond of phosphoglycerides. We measured M-PLA2 concentration in tissue extracts from 325 human breast cancers using a specific radioimmunoassay recently developed. Correlation analyses between the tissue concentration of M-PLA2 and clinicopathological factors showed that the enzyme level was significantly higher in patients with distant metastasis than in those without. In addition, M-PLA2 concentration was significantly higher in scirrhous carcinoma than in other histological types. No significant association was found between M-PLA2 concentration and age, menstrual status, tumour size, histological grade, vessel involvement or oestrogen receptor (ER) and progesterone receptor (PR) status. The expression of M-PLA2 mRNA was examined in a fibroadenoma, a stage IV breast cancer and its metastatic site of skin. Northern blot analysis showed a clear hybridisation band corresponding to M-PLA2 mRNA in both primary breast cancer and its metastatic site, while the fibroadenoma expressed a faint band corresponding to M-PLA2 mRNA. Breast cancer patients with high M-PLA2 concentrations exhibited significantly shorter disease-free and overall survival than those with low M-PLA2 concentration at the cut-off point of 5 ng 100 mg-1 protein, which was determined in a separate study. In multivariate analysis, M-PLA2 was found to be an independent prognostic factor for disease recurrence and death in human breast cancer. The possible significance of M-PLA2 expression in human breast cancer tissue is discussed.

Increased expression of membrane-associated phospholipase A2 shows malignant potential of human breast cancer cells

Background. Recently, the authors reported that membrane‐associated phospholipase A2 (M‐PLA2) was one of the acute phase reactants and increased in serum of patients with various malignant tumors.

Elevation of serum group II phospholipase A2 levels in patients with advanced cancer

To investigate the role of group II phospholipase A2 (M-PLA2) in cancer, we examined M-PLA2 serum levels in 170 pre-operative patients with various cancers and found elevated levels in 49% of them. M-PLA2 serum levels were significantly higher in patients with tumor stages T2-4, N1, M1 and stages II to IV than in T1, N0, M0 and stage I tumors, respectively. In all nine post-operative patients tested, M-PLA2 decreased 14 days after tumor resection and reduced to normal levels in 4 patients. Six of 16 carcinoma cell lines (37.5%) spontaneously secreted M-PLA2 into the culture supernatant despite the absence of IL-6 and IL-1 in 5 of the 6 lines. These results demonstrate that M-PLA2 produced by cancer cells may contribute, at least in part, to the elevation of serum M-PLA2 levels observed in cancer patients.

Production of immunoreactive polymorphonuclear leucocyte elastase in human breast cancer cells: possible role of polymorphonuclear leucocyte elastase in the progression of human breast cancer

Breast cancer cells are known to express various proteolytic enzymes, which make them invasive and favour their dissemination to distant sites. However, it is unclear whether breast cancer cells have the ability to produce polymorphonuclear leucocyte elastase (PMN-E). We measured immunoreactive (ir) PMN-E content in the conditioned medium of two breast cancer cell lines, MCF-7 and ZR-75-1, and two normal breast epithelial cell lines, HBL-100 and Hs 578Bst, using a highly specific and sensitive enzyme immunoassay. Furthermore, ir-PMN-E content was determined in tissue extracts from 62 human breast cancers. ir-PMN-E content in the culture medium of MCF-7 cells and ZR-75-1 cells increased as a function of time, regardless of the presence or absence of oestradiol. On the other hand, no detectable ir-PMN-E was secreted into the culture medium of HBL-100 and Hs 578Bst cells. ir-PMN-E was detectable in 59 of 62 tissue extracts prepared from human breast cancers, the concentration ranging from 0.12 to 19.17 micrograms per 100 mg of protein. When 62 breast cancer specimens were categorised into four groups in terms of clinical stage, ir-PMN-E content in breast cancer tissue was significantly higher in stage III (8.90 +/- 5.13 micrograms 100 mg-1 protein) and stage IV (12.19 +/- 5.44 micrograms 100 mg-1 protein) patients than in stage I (1.64 +/- 1.54 micrograms 100 mg-1 protein) and stage II (4.23 +/- 3.74 micrograms 100 mg-1 protein) patients. Breast cancer patients with high levels of ir-PMN-E showed significantly shorter disease-free survival and overall survival than those with low levels of ir-PMN-E at the cut-off point of 8.99 micrograms 100 mg-1 protein. In the multivariate analysis, ir-PMN-E content was found to be a significant prognostic factor for disease recurrence and death in human breast cancer.

Differential biological significance of tissue-type and urokinase-type plasminogen activator in human breast cancer.

Plasminogen activator (PA) is a serine protease existing in two forms known as tissue-type (t-PA) and urokinase-type (u-PA). To examine whether PA is related to the postoperative clinical course of human breast cancer, total PA activity, t-PA activity, u-PA activity, and immunoreactive t-PA were determined in tissue extracts from 144 breast cancer specimens. The patients were initially divided into four groups according to the postoperative clinical course: Group I (83 patients who are disease-free), Group II (20 patients whose first metastases were found only in bone), Group III (19 patients whose first metastases were found in both bone and lung), and Group IV (22 patients whose first metastases were found only in lung). Total PA activity was significantly lower in Groups, II, III and IV than in Group I. Both t-PA activity and t-PA antigen levels were also significantly lower in Groups II, III and IV than in Group I, while no significant difference was found in u-PA activity among these groups, indicating that low activity of total PA in Groups II, III and IV was due to a decrease in t-PA but not in u-PA. In the multivariate analyses, t-PA activity was found to be an independent prognostic factor for relapse-free survival. When four groups of patients were further analysed in terms of nodal status, both t-PA activity and antigen levels were markedly decreased in the node-negative Group II compared with the node-negative Groups III and IV or with the node-positive Groups II, III and IV. Of additional interest, u-PA activity was significantly higher in node-positive patients than in node-negative patients with any group. The clinico-pathologic analyses of the patients in this series showed that node involvement and lymphatic invasion were more frequently positive in Groups III and IV than in Groups I and II. When 144 breast cancers were categorised in terms of combinations of oestrogen receptor (ER) and progesterone receptor (PgR) status, breast cancers which were positive for both receptors were found to contain the highest t-PA activity and antigen. This study provides provocative evidence suggesting a possible differential significance of t-PA and u-PA expression in human breast cancer.

Breast cancer prognosis is poor when total plasminogen activator activity is low

Plasminogen activator (PA) is a serine protease which exists in two forms: tissue-type (t-PA) and urokinase-type (u-PA). The total PA activity was measured in tumour extracts of 235 breast cancer patients who were followed for a median of 8.5 years after surgery. Patients were initially divided into three groups with low (< 60 units mg-1 protein), intermediate (60-300 unit mg-1 protein), or high (> 300 unit mg-1 protein) total PA activity in tumour extracts. The PA activity was not significantly associated with the recognised prognostic factors of age, menstrual status, tumour size, lymph node involvement, histologic type, grade of anaplasia, and/or vessel involvement. A significant association was found between total PA activity and the oestrogen receptor (ER) or progesterone receptor (PgR) status. Among receptor-positive tumours, a significantly greater proportion of patients had high PA activity in their tumour extracts. Breast cancer patients with low total PA activity had a significantly shorter disease-free and overall survival rate when compared to those with intermediate or high PA activity. In univariate and multivariate analyses, total PA activity (< 60 unit mg-1 vs > or = 60 unit mg-1 protein) was found to be a significant prognostic factor for disease-free and overall survival of about the same import as lymph node involvement. Furthermore, the combination of total PA activity and nodal status could be even more precise in predicting survival times and probabilities in individual patients. This retrospective study demonstrates the total PA activity is a valuable prognostic factor in determining prognosis in human breast cancer.

Acute suppurative thyroiditis in an asymptomatic woman: an atypical presentation simulating thyroid carcinoma

Patients with acute suppurative thyroiditis usually have pain or tenderness in the anterior part of the neck associated with erythema and dysphagia. A 26‐year‐old Japanese woman with none of these symptoms presented with a left anterior cervical mass. Since physical examination and laboratory studies showed a firm and irregular tumour located in the left lobe of the thyroid without any inflammatory signs, we made a diagnosis of thyroid carcinoma. After surgery, histological examination of the thyroid specimen revealed various changes of severe inflammation, and a barium swallow demonstrated a left pyriform sinus fistula. We describe here a unique case of acute suppurative thyroiditis in an asymptomatic woman.

Tissue-type plasminogen activator is involved in skeletal metastasis from human breast cancer

SummaryThis study was undertaken to determine if primary breast tumor plasminogen activator expression correlates with skeletal metastasis in breast cancer. Total plasminogen activator activity was significantly lower in tumors of patients with recurrence than in recurrence-free patients. Similarly, the primary tumors of patients with skeletal metastasis contained considerably less enzyme activity compared with those of patients surviving without skeletal metastasis. When patients with skeletal metastasis were categorized in terms of their recurrence pattern, those who had skeletal metastasis without other organ metastasis had significantly less tissue-type plasminogen activator antigen in their primary breast tumors than did those who had metastasis to other organs. Furthermore, a significantly lower level of tissue-type plasminogen activator antigen was found in primary tumors associated with axial bone metastasis than in those associated with appendicular bone metastasis. These results suggest that tissue-type plasminogen activator is involved in skeletal metastasis formation by its effects through the vertebral venous plexus.

Demonstration of a possible link between high grade malignancy in dimethylbenz[a]anthracene-induced rat mammary carcinoma and increased urokinase plasminogen activator content.

SummaryRecent reports have suggested that tissue-type plasminogen activator activity is regulated by estrogen in 7,12-dimethylbenz[a]anthracene-induced rat mammary carcinoma type I cells but is not necessarily regulated by estrogen in type II mammary carcinoma cells. We have compared the biological features of these two types of mammary carcinoma cells and have found that, although there is no difference in estrogen receptor content between these two cell types, the plasminogen activator activity markedly differs. Tissue-type plasminogen activator activity is significantly higher in type I carcinoma than in type II carcinoma, urokinase-type activity is significantly higher in type II carcinoma than in type I carcinoma. When these two types were compared in terms of rate of tumor growth, type II carcinomas clearly showed more rapid growth than type I carcinomas. Survival studies showed significantly shorter survival of type II tumor-bearing rats compared with type I tumor-bearing rats. Furthermore, type II carcinomas contained a greater proportion of aneuploid cells than type I carcinomas. These results suggest that type II carcinoma cells, in which estrogen is unable to regulate tissue-type plasminogen activator activity, are considered to be of a higher grade of malignancy than type I carcinoma cells.

Hormonal regulation of plasminogen activator and peroxidase activities in 7,12-dimethylbenz(a)anthracene-induced rat mammary tumors and the rat uterus

Oophorectomy was found to decrease the plasminogen activator activity of rat mammary tumors induced by 7,12-dimethylbenz(a) anthracene (DMBA) to less than 7 per cent, whilein vivo estradiol treatment restored its activity in a dose dependent fashion. The peroxidase activity was not changed either by oophorectomy or by the administration of estrogen. In the rat uterus, plasminogen activator activity was not changed by oophorectomy or by the administration of estrogen, however, its peroxidase activity decreased to less than 2 per cent following oophorectomy, while estrogen administration restored its activity. Estrogen regulated plasminogen activator activity in the DMBA-induced rat mammary tumors but not in the uterus and thus, the specific hormonal regulation of this enzyme may be an important factor for the hormonal dependent growth of such tumors.