Expression of MAGE tumour-associated antigens is inversely correlated with tumour differentiation in invasive ductal breast cancers: an immunohistochemical study.

MAGE (Melanoma antigen E) family gene products encompass tumour-associated antigens (TAAs) recognised by human leukocyte antigen (HLA)-restricted specific T-cells. Agents inducing DNA demethylation, an event typically detectable in cellular de-differentiation processes, were shown to induce the expression of MAGE genes. By using a monoclonal antibody specific for MAGE family gene products, we have studied the expression of these TAAs in a group of 144 patients with invasive ductal breast cancers. Immunohistochemical data were correlated with tumour differentiation, lymphatic vessel invasion, oestrogen receptor expression, intratumoural necrosis, lymphocytic infiltration, perineural invasion, tumour microcalcifications and axillary lymph node metastases. MAGE immunoreactivity was undetectable in non-neoplastic cells. In poorly differentiated cancers positive staining was observed in 30/63 cases (47.6%) as compared with 13/51 (25.4%) and 5/30 (16.6%) in moderately and well-differentiated tumours, respectively (P<0.05). In addition, MAGE immunoreactivity was significantly correlated with lymphatic vessel invasion and intratumoural necrosis. Moreover, a significant inverse relationship with oestrogen receptor expression was also observed. However, no significant correlation could be established between MAGE immunoreactivity and defined phenotypic characteristics of tumour infiltrating lymphocytes, including expression of CD3, CD4, CD8, CD20 or granzyme B. Thus, expression of MAGE family gene products in invasive ductal breast cancers appears to be associated with poorly differentiated histological phenotypes. These data support the concept of specific immunotherapy in highly aggressive forms of breast neoplasms. Furthermore, they suggest that MAGE immunoreactivity could represent a tumour marker of potential prognostic relevance.

SET-related cell division autoantigen-1 (CDA1) arrests cell growth.

We used an autoimmune serum from a patient with discoid lupus erythematosus to clone a cDNA of 2808 base pairs. Its open reading frame of 2079 base pairs encodes a predicted polypeptide of 693 amino acids named CDA1 (cell division autoantigen-1). CDA1 has a predicted molecular mass of 79,430 Daltons and a pI of 4.26. The size of the cDNA is consistent with its estimated mRNA size. CDA1 comprises an N-terminal proline-rich domain, a central basic domain, and a C-terminal bipartite acidic domain. It has four putative nuclear localization signals and potential sites for phosphorylation by cAMP and cGMP-dependent kinases, protein kinase C, thymidine kinase, casein kinase II, and cyclin-dependent kinases (CDKs). CDA1 is phosphorylated in HeLa cells and by cyclin D1/CDK4, cyclin A/CDK2, and cyclin B/CDK1 in vitro. Its basic and acidic domains contain regions homologous to almost the entire human leukemia-associated SET protein. The same basic region is also homologous to nucleosome assembly proteins, testis TSPY protein, and an uncharacterized brain protein. CDA1 is present in the nuclear fraction of HeLa cells and localizes to the nucleus and nucleolus in HeLa cells transfected with CDA1 or its N terminus containing all four nuclear localization signals. Its acidic C terminus localizes mainly to the cytoplasm. CDA1 levels are low in serum-starved cells, increasing dramatically with serum stimulation. Expression of the CDA1 transgene, but not its N terminus, arrests HeLa cell growth, colony numbers, cell density, and bromodeoxyuridine uptake in a dose-dependent manner. The ability of CDA1 to arrest cell growth is abolished by mutation of the two CDK consensus phosphorylation sites. We propose that CDA1 is a negative regulator of cell growth and that its activity is regulated by its expression level and phosphorylation.

Insulin/insulin-like growth factor-I and estrogen cooperate to stimulate cyclin E-Cdk2 activation and cell Cycle progression in MCF-7 breast cancer cells through differential regulation of cyclin E and p21(WAF1/Cip1).

Estrogens and insulin/insulin-like growth factor-I (IGF-I) are potent mitogens for breast epithelial cells and, when co-administered, induce synergistic stimulation of cell proliferation. To investigate the molecular basis of this effect, a MCF-7 breast cancer cell model was established where serum deprivation and concurrent treatment with the pure estrogen antagonist, ICI 182780, inhibited growth factor and estrogen action and arrested cells in G(0)/G(1) phase. Subsequent stimulation with insulin or IGF-I alone failed to induce significant S-phase entry. However, these treatments increased cyclin D1, cyclin E, and p21 gene expression and induced the formation of active Cdk4 complexes but resulted in only minor increases in cyclin E-Cdk2 activity, likely due to recruitment of the cyclin-dependent kinase (CDK) inhibitor p21(WAF1/Cip1) into these complexes. Treatment with estradiol alone resulted in a greater increase in cyclin D1 gene expression but markedly decreased p21 expression, with a concurrent increase in Cdk4 and Cdk2 activity and subsequent synchronous entry of cells into S phase. Co-administration of insulin/IGF-I and estrogen induced synergistic stimulation of S-phase entry coincident with synergistic activation of high molecular mass (approximately 350 kDa) cyclin E-Cdk2 complexes lacking p21. To determine if the ability of estrogen to deplete p21 was central to these effects, cells stimulated with insulin and estradiol were infected with an adenovirus expressing p21. Induction of p21 to levels equivalent to those following treatment with insulin alone markedly inhibited the synergism between estradiol and insulin on S-phase entry. Thus the ability of estradiol to antagonize the insulin-induced increase in p21 gene expression, with consequent activation of cyclin E-Cdk2, is a central component of the synergistic stimulation of breast epithelial cell proliferation induced by simultaneous activation of the estrogen and insulin/IGF-I signaling pathways.

Angiogenesis in malignant tumors.

Angiogenesis is the formation of new blood vessels from the existing vascular network. It is a complex, multi-step process involving extracellular matrix remodeling, endothelial cell migration and proliferation, capillary differentiation, and anastomoses. Angiogenesis is crucial for tumor progression and metastasizing. Intratumor microvessel density is believed to reflect the degree of angiogenesis in carcinomas. Angiogenesis is also very important in many preneoplastic lesions.

Phosphorylation at the cyclin-dependent kinases site (Thr85) of parathyroid hormone-related protein negatively regulates its nuclear localization.

Parathyroid hormone-related protein (PTHrP) is expressed by a wide variety of cells and is considered to act as a secreted factor; however, evidence is accumulating for it to act in an intracrine manner. We have determined that PTHrP localizes to the nucleus at the G1 phase of the cell cycle and is transported to the cytoplasm when cells divide. PTHrP contains a putative nuclear localization sequence (NLS) (residues 61-94) similar to that of SV40 T-antigen, which may be implicated in the nuclear import of the molecule. We identified that Thr85 immediately prior to the NLS of PTHrP was phosphorylated by CDC2-CDK2 and phosphorylation was cell cycle-dependent. Mutation of Thr85 to Ala85 resulted in nuclear accumulation of PTHrP, while mutation to Glu85 to mimic a phosphorylated residue resulted in localization of PTHrP to the cytoplasm. Combined, the data demonstrate that the intracellular localization of PTHrP is phosphorylation- and cell cycle-dependent, and such control further supports a potential intracellular role (10,34,35) for PTHrP.

A cyclin D-Cdk4 activity required for G2 phase cell cycle progression is inhibited in ultraviolet radiation-induced G2 phase delay.

Cyclin D-Cdk4 complexes have a demonstrated role in G1 phase, regulating the function of the retinoblastoma susceptibility gene product (Rb). Previously, we have shown that following treatment with low doses of UV radiation, cell lines that express wild-type p16 and Cdk4 responded with a G2 phase cell cycle delay. The UV-responsive lines contained elevated levels of p16 post-treatment, and the accumulation of p16 correlated with the G2 delay. Here we report that in UV-irradiated HeLa and A2058 cells, p16 bound Cdk4 and Cdk6 complexes with increased avidity and inhibited a cyclin D3-Cdk4 complex normally activated in late S/early G2 phase. Activation of this complex was correlated with the caffeine-induced release from the UV-induced G2 delay and a decrease in the level of p16 bound to Cdk4. Finally, overexpression of a dominant-negative mutant of Cdk4 blocked cells in G2 phase. These data indicate that the cyclin D3-Cdk4 activity is necessary for cell cycle progression through G2 phase into mitosis and that the increased binding of p16 blocks this activity and G2 phase progression after UV exposure.

Apoptosis in human gastric polyps and adenocarcinomas: a stereological analysis.

BACKGROUND/AIM: The occurrence of apoptotic cells was analyzed in human normal gastric mucosa, polyps and adenocarcinomas. METHODOLOGY: Histological classification was carried out on hematoxylin and eosin stained slides. The tissue was classified as follows: Normal gastric mucosa or adenomatous polyps. Gastric carcinoma specimens were histologically classified according to Lauren's classification into: A: Diffuse adenocarcinoma without metastasis, B: Diffuse adenocarcinoma with metastasis, C: Intestinal adenocarcinoma without metastasis, D: Intestinal adenocarcinoma with metastasis, E: Mixed adenocarcinoma without metastasis and mixed adenocarcinoma with metastasis. The counting of apoptotic cells was performed using the 40X objective with a calibrated eyepiece Weibel's multi-purpose M 42 stereological test system. Each group was evaluated stereologically, determining numeric density of apoptotic cells. RESULTS: The results show the progressive and statistically significant increase of apoptotic numeric densities from normal gastric epithelium to adenomatous polyp and finally to cancer, which contained the highest number of apoptotic cells. Comparing gastric carcinoma with and without metastasis in intestinal and diffuse adenocarcinoma there was statistically significant difference. In these two groups, carcinomas with metastasis contained higher number of apoptotic cells than without metastasis. Gastric cancer according to numeric densities of apoptotic cells can be separated in tree statistically different groups: A: Intestinal type gastric cancer with metastasis (the highest number of apoptotic cells), B: Intestinal type gastric cancer without metastasis and diffuse gastric cancer with metastasis (medium number), C: Diffuse type gastric cancer without metastasis, mixed gastric cancer with and without metastasis (the lowest number of apoptotic cells). CONCLUSION: These results suggest that numeric densities of apoptotic cells are associated with tumor progression in human gastric carcinogenesis and can be used as prognostic mark.

[Prognostic value of determination of the presence and histologic grade of the intraductal component in invasive ductal carcinoma of the breast after conservative treatment]. / Prognosticka vrijednost odredivanja prisutnosti i histoloskog stupnja intraduktalne komponente invazivnog duktalnog karcinoma dojke nakon postednog lijecenja.

In recent years, breast-conserving therapy and radiation therapy have become an important treatment option for patients with stage I and II invasive breast cancer. The results of long-term retrospective studies have demonstrated that this treatment can provide a high level of local tumor control with satisfactory cosmetic results. Numerous studies have shown that the presence of extensive intraductal component (prominent intraductal carcinoma) is highly associated with subsequent local recurrence. In this article we have stressed the value of the determination of the presence and the histologic grade of prominent intraductal component of invasive ductal breast carcinoma in the determination of the extent of surgery. We also point out the possibility of determination of prominent DCIS on frozen sections.

Estrogen-induced activation of Cdk4 and Cdk2 during G1-S phase progression is accompanied by increased cyclin D1 expression and decreased cyclin-dependent kinase inhibitor association with cyclin E-Cdk2.

Estrogens induce cell proliferation in target tissues by stimulating progression through G1 phase of the cell cycle, but the underlying molecular targets remain undefined. To determine the role of the cyclin/cyclin-dependent kinase (CDK)/retinoblastoma protein (pRB) pathway in this response we treated MCF-7 breast cancer cells with the pure estrogen antagonist ICI 182780 to inhibit estrogen-induced gene expression and induce G1 phase arrest. Subsequent treatment with 17beta-estradiol resulted in the synchronous entry of cells into S phase commencing at 12 h. The proportion of cells in S phase reached a maximum of 60% at 21-24 h. Cells subsequently completed mitosis and entered a second semisynchronous round of replication. Entry into S phase was preceded by increased activity of both Cdk4 and cyclin E-Cdk2 and hyperphosphorylation of pRB, all within the first 3-6 h of estradiol treatment. The increase in Cdk4 activity was accompanied by increases in cyclin D1 mRNA and protein, indicating that an initiating event in the activation of Cdk4 was increased cyclin D1 gene expression. In contrast, the levels of Cdk2 and the CDK inhibitors p21 (WAF1/CIP1/SDI1) and p27 (KIP1) in total cell lysates and in cyclin E immunoprecipitates were unaltered at these early time points. However, an inhibitory activity was present in antiestrogen-pretreated cell lysates toward recombinant cyclin E-Cdk2 and was relieved by estradiol treatment. This activity was attributable predominantly to p21. These apparently conflicting data were resolved by performing gel filtration chromatography, which revealed that only a minority of cyclin E-Cdk2 complexes were active following estradiol treatment. Active complexes eluted at a higher molecular weight than inactive complexes, were relatively deficient in both p21 and p27, and contained Cdk2 with increased threonine 160 phosphorylation, consistent with a mechanism of activation of cyclin E-Cdk2 involving both reduced CDK inhibitor association and CDK-activating kinase-mediated phosphorylation of Cdk2. These results provide an explanation for the early activation of both cyclin D1-Cdk4 and cyclin E-Cdk2 complexes that accompany G1-S phase progression in response to estradiol.

Cyclin D2 activates Cdk2 in preference to Cdk4 in human breast epithelial cells.

To investigate the possibility of differing roles for cyclins D1 and D2 in breast epithelial cells, we examined the expression, cell cycle regulation and activity of these two G1 cyclins in both 184 normal breast epithelial cells and T-47D breast cancer cells. Synchronisation studies in 184 cells demonstrated that cyclin D1 and cyclin D2 were differentially regulated during G1, with cyclin D2 abundance increasing by 3.7-fold but only small changes in cyclin D1 abundance observed. The functional consequences of increased cyclin D2 expression were examined in T-47D cells, which express no detectable cyclin D2. Induced expression of cyclin D2 resulted in increases in cyclin E expression, pRB phosphorylation and the percentage of cells in S-phase, while constitutive expression resulted in a consistent trend toward reduced dependence on serum for continued proliferation. Thus, cyclin D2 is a positive regulator of G1 progression in breast cells analogous to the well-documented effects of cyclin D1. Indeed, equimolar concentrations of inducible cyclin D1 and D2 resulted in quantitatively similar cell cycle effects. Marked divergence was found, however, in the CDKs activated by the two cyclins in breast epithelial cells. Cyclin D2 complexes contained a higher Cdk2/Cdk4 ratio than cyclin D1 complexes. The cyclin D2-associated kinase activity was largely inhibited by Cdk2-specific inhibitors and could phosphorylate histone H1, a substrate for Cdk2 but not for Cdk4 and Cdk6. Therefore, cyclin D2 preferentially activated Cdk2 in breast epithelial cells. In contrast, Cdk4 and Cdk6 were predominantly responsible for cyclin D1-associated kinase activity as previously reported. Thus, although cyclins D1 and D2 elicited similar effects on breast epithelial cell cycle progression they appeared to achieve this end via activation of different CDKs. This is the first evidence of cyclin D2 activating Cdk2 in mammalian cells thus providing further evidence that D-type cyclins are not necessarily redundant.

Differential phosphorylation of T-47D human breast cancer cell substrates by D1-, D3-, E-, and A-type cyclin-CDK complexes.

The cyclin-dependent kinases (CDKs) promote cell cycle transitions in mammalian cells by phosphorylation of key substrates. To characterize substrates of the G1 and S phase cyclin-CDK complexes, including cyclin D1-CDK4, cyclin D3-CDK4, cyclin D3-CDK6, cyclin E-CDK2, and cyclin A-CDK2, which are largely undefined, we phosphorylated T-47D breast cancer cell nuclear lysates partially purified by ion-exchange chromatography with purified baculovirus expressed cyclin-CDK complexes. A comparison of the substrates that were phosphorylated by the different cyclin D-CDKs revealed some common as well as specific substrates. Hence, cyclin D1-CDK4 specifically phosphorylated a 38-kDa protein while cyclin D3-CDK4 specifically phosphorylated proteins of 105, 102, and 42 kDa. A 24-kDa protein was phosphorylated by both complexes. Cyclin D3-CDK6 exhibited similar substrate preferences to cyclin D3-CDK4, phosphorylating the 105- and 102-kDa proteins but not the 24-kDa protein. Hence, both the cyclin D1 and D3 as well as CDK4 and CDK6 subunits can confer substrate specificity on the overall cyclin D-CDK complex. Cyclin E-CDK2 and cyclin A-CDK2 phosphorylated a greater number of substrates than the cyclin D-CDKs, ranging in size from 10 kDa to over 200 kDa. Twenty-two substrates were common to both complexes, while six were specific for cyclin A-CDK2 and only one protein of 34 kDa was specific for cyclin E-CDK2. These studies indicate that cyclins E and A modulate the specificity of CDK2 and have demonstrated substrates that may be important for the specific roles of these cyclin-CDKs during G1 and S phase progression. Protein sequencing of one of the cyclin-CDK substrates characterized in this study identified this protein as nucleolin, a previously characterized CDC2 (CDK1) substrate, thus indicating the utility of this approach in identifying cyclin-CDK targets. These results show that both the cyclin and CDK subunits can regulate the substrate specificity of the overall cyclin-CDK complex and have demonstrated numerous substrates of D-, E-, and A-type cyclin-CDK complexes potentially involved in regulating transit through the G1 and S phases of the cell cycle.

[Pathohistologic procedures in encapsulated follicular tumors of the thyroid gland]. / Osobitosti pathohistoloske obrade ocahurenih folikularnih tumora stitne zlijezde.

Determination of pathohistologic diagnosis of encapsulated thyroid tumors, particularly follicular carcinoma, is sometimes very difficult, even for well-experienced pathologists. The analysis of intraoperative biopsies could be even more difficult. The importance of proper handling of bioptic material for correct interpretation of pathohistologic findings is not adequately stressed in our literature. In this article, we point out necessity of serial sections of encapsulated follicular tumors for correct diagnosis.

Cancer-associated mis-sense and deletion mutations impair p16INK4 CDK inhibitory activity.

The p16INK4 gene is a candidate tumour-suppressor gene which maps to the genomic locus 9p21, and mutations of this gene are associated with melanoma and other cancers. Biochemical studies suggest that p16INK4 mediates its effects by specifically inhibiting the G1 cyclin-dependent kinases CDK4 and CDK6, thereby regulating the progression through G1 into S phase of the cell cycle. To evaluate the functional effects of mutations in p16INK4 which have been observed in primary cancers and cancer cell lines, we constructed a series of deletion mutants comprising amino acid regions 9-72, 9-131, 73-131 and 73-156; a mis-sense mutation identified in melanoma (Arg87Pro); and the polymorphism Ala48Thr and investigated their ability to inhibit cyclin D1/CDK4 kinase activity in vitro. Removal of 25 amino acids from the carboxy terminus of p16INIK4 (9-131) had little impact on its inhibitory activity. In contrast, deletion of the 65 N-terminal amino acids comprising the first and second ankyrin repeats of p16INK4 (73-131) abolished its inhibitory activity. The carboxy (73-156) and amino termial (9-72) fragments of p16INK4 also failed to inhibit cyclin D1/CDK4 activity. These results indicate that the core region (73-131) as well as amino acids N-terminal of this sequence are important, whereas sequences C-terminal of amino acid 131 are less important for the inhibitory activity of this molecule. The melanoma-associated Arg87Pro mutation resulted in loss of inhibitory activity, whereas the Ala148Thr polymorphic variant was as effective as the alanine variant of p16INK4 in inhibiting D1/CDK4 kinase activity. Binding assays revealed that inhibition was invariably associated with p16INK4 binding to CDK4. Hence, our studies indicate that minor perturbations in p16INK4 primary structure can lead to loss of its inhibitory activity, possibly contributing to oncogenesis in numerous cell types.

Inducible expression of cyclin D1 in T-47D human breast cancer cells is sufficient for Cdk2 activation and pRB hyperphosphorylation.

The sequential transcriptional activation of cyclins, the regulatory subunits of cell cycle specific kinases, regulates progress through the cell cycle. In mitogen-stimulated cells cyclin D1 induction in early G1 is followed by induction of cyclin E, activation of the cyclin-dependent kinase Cdk2, and hyperphosphorylation of the retinoblastoma gene product (pRB) in mid-to-late G1 phase. T-47D breast cancer cells expressing cyclin D1 under the control of a metal-responsive metallothionein promoter were used to determine whether Cdk2 activation and pRB hyperphosphorylation are consequences of cyclin D1 induction. A 4-5-fold increase in cyclin D1 protein abundance was followed by approximately 2-fold increases in cyclin E protein abundance and Cdk2 activity and by hyperphosphorylation of pRB. These responses were apparent approximately 3 h after the increase in cyclin D1 protein, and approximately 3 h prior to the entry of cyclin D1-stimulated cells into S phase 12 h after zinc treatment. Cyclin D1 immunoprecipitates contained Cdk4 but no detectable Cdk2 and displayed pRb but not histone H1 kinase activity. Cdk2 activation was therefore likely to be due to increased abundance of cyclin E/Cdk2 complexes rather than formation of active cyclin D1/Cdk2 complexes. The sequence of events following zinc induction of cyclin D1 thus mimicked that following mitogen induction of cyclin D1. These data show that cyclin D1 induction is sufficient for Cdk2 activation and pRB hyperphosphorylation in T-47D human breast cancer cells, providing evidence that cyclin D1 induction is a critical event in G1 phase progression.

Detection of human papillomavirus (HPV) type 6, 16 and 18 in head and neck squamous cell carcinomas by in situ hybridization.

Seventy seven squamous cell carcinomas (10 oral cavity, 15 tongue, 26 pharynx and 26 larynx), with different grading, were analyzed for the presence of HPV DNA by in situ hybridization. Positive signals were found on the nuclei of cancer cells in 25 (32.5%), in the epithelia adjacent to squamous cell carcinomas in 2 (8.7%), and in the resected margins in 1 (4.3%) case. HPV DNA positive signals were obtained in 42% of laryngeal, 34% of pharyngeal, in 20% of oral, and 20% of tongue carcinomas. Out of 25 HPV positive carcinomas a single HPV type was detected in at least 11 (44%), and double or multiple infection in 9 (36%) cases; altogether, HPV 6 DNA was determined in 15 (60%), and HPV 16 and/or 18 DNA in 17 (68%) head and neck tumors. The detection rate of HPV 6 was lower than of HPV 16 and/or 18 for tumors in oral cavity, tongue and larynx. Out of 25 HPV DNA positive carcinomas 21% were graded as G1, 27% as G2, and 44% were G3. The results indicate that HPV may be involved in the pathogenesis of head and neck squamous cell carcinomas.

Differential effects of retinoids and antiestrogens on cell cycle progression and cell cycle regulatory genes in human breast cancer cells.

Retinoids have antiproliferative effects in human breast cancer cells and share some characteristics with antiestrogens, although the molecular targets involved have yet to be identified in either case. Using T-47D human breast cancer cells, we compared the effects of retinoic acid (RA) and the antiestrogen ICI 164384 on cell cycle phase distribution and the expression of genes with known functions in cell cycle control. Both RA and ICI 164384 inhibited cell cycle progression in G1 phase, but the RA effect was delayed by 16 h. This delay in action was also seen with 9-cis RA and other retinoids. Administration of 17 beta-estradiol abolished the effects of ICI 164384 but was without effect in RA-treated cells. Antiestrogen treatment caused a rapid inhibition of c-myc and cyclin D1 gene expression and reduced Cdk2 activity by more than 50% at 24 h. RA, however, did not affect c-myc or cyclin D1 gene expression, nor did it significantly change the mRNA or protein levels of cyclins D3 or E or cyclin-dependent kinases (CDK) Cdk2 or Cdk4. RA-induced reduction in Cdk2 activity was modest and occurred after %S phase declined, while Cdk4 activity was reduced, coincident with cell cycle changes. However, following either RA or ICI 164384, there was a reduction in the amount of hyperphosphorylated pRB, first apparent well before cell cycle changes were seen. These data demonstrate that: (a) the mechanisms of action of antiestrogens and retinoids are different but converge at pRB; and (b) RA can affect CDK activity without reducing cyclin or CDK levels.

Fibromatosis of male breast.

Fibromatosis is a relatively benign, though locally invasive neoplasm. About 100 cases of fibromatosis of the breast have been reported to date, none of them in a male. We present a 60-year-old man who was admitted to the University Hospital for Tumors in Zagreb, Croatia, on May 25, 1992, with a 3-month history of gradually enlarging, painless subcutaneous mass, 6 x 5 cm, that was located in the upper outer quadrant and partly beneath the areola of his left breast. The diagnosis was confirmed by immunoperoxidase studies, that showed positivity for vimentin, whereas the staining for cytokeratin AE1, glial fibrillar acid protein (GFAP) and collagen IV was negative. The tumor was removed by en bloc resection, and the greater pectoral muscle was spared. Today, 3 years after the operation, the patient is alive and in good health.

Locally recurring primary myxoma of the breast: an evidence of malignant alteration.

Breast is an extremely rare localization of myxoma. To date, only five cases have been reported, including one case of nerve sheath myxoma. In this report, the authors present a 37-year-old female patient who was admitted to the University Hospital for Tumors in Zagreb, Croatia, in 1979, with a 2-month history of gradually enlarging, painless subcutaneous mass in her right breast. On physical examination, a firm, relatively well circumscribed mass measuring 3 x 2 cm was detected in the upper outer quadrant and partly beneath the areola. The mass was freely movable to the overlying skin, causing no retraction. There was no family history of a breast disease or cancer. Patient's past history revealed no major illnesses or trauma. The tumor was removed by simple local excision, but it recurred locally in three episodes between 1981 and 1986. After that, the tumor underwent malignant alteration to myxosarcoma on its fourth (in 1992), and to myxoid liposarcoma on its fifth recurrence (in 1993). No such sequence of events has been reported in the literature so far.

Antiestrogen inhibition of cell cycle progression in breast cancer cells in associated with inhibition of cyclin-dependent kinase activity and decreased retinoblastoma protein phosphorylation.

To define the mechanisms by which antiestrogens inhibit breast cancer cell proliferation, the effects of the antiestrogen ICI 182780 on G1 cyclins and their cyclin-dependent kinase (CDK) partners were investigated in MCF-7 cells. Inhibition of entry into S phase became evident 9 h after treatment, with the proportion of cells in S phase reaching a minimum by 24 h. ICI 182780 increased the proportion of the hypophosphorylated, growth inhibitory form of the retinoblastoma protein (pRB). This change began at 4-6 h, preceding effects on S phase. This suggests that there are early effects on the activities of CDKs that target pRB that are not merely a consequence of changes in cell cycle progression. The kinase activity of Cdk2 decreased to low levels at 18-24 h when changes in S phase and pRB phosphorylation were well advanced. An earlier effect was seen on kinase activity associated with immunoprecipitated cyclin D1, which was reduced approximately 40% by 12 h, with further decreases at 18-24 h. Cdk2 and Cdk4 protein levels remained constant over 24 h. Cyclin D1 messenger RNA and protein were down-regulated by ICI 182780 from 2 h, with levels halved at 8 h. ICI 182780 also increased the expression of the CDK inhibitors p27KIP1 and p21WAF1/CIP1 at later times. These observations are compatible with the hypothesis that antiestrogens block entry of cells into S phase and inhibit cell proliferation as the consequence of an early decline in pRB phosphorylation contributed to by reduced cyclin D1/Cdk4 activity. At later times, increased CDK inhibitor abundance may act to repress Cdk2 and Cdk4 activities, causing additional reductions in pRB phosphorylation, thus maintaining the antiestrogen blockade of cell cycle progression.

[Relation between grades of histologic differentiation and hormone receptors in breast cancer]. / Odnos izmedu stupnja histoloske diferenciranosti i hormonskih receptora kod raka dojke.

The relationship between the grade of histologic differentiation of the tumor and estrogen (ER) and progesterone (PgR) receptor values was analyzed in 261 patients with breast cancer of the invasive duct type. There was a statistically significant difference in concentration and incidence of positive and negative ER and PgR with regard to histologic grade. The concentration and number of positive hormone receptors increased with better differentiation of the tumor. A statistically significant correlation between histologic grade, hormone receptor values and axillary nodal involvement was obtained only in patients with no metastases to axillary lymph nodes.