Prognostic value of tumor: Infiltrating lymphocytes and androgen receptors correlation in triple negative breast cancer

e12571

Background: Little is known about correlation of tumor infiltrating lymphocytes (TIL) and androgen receptors (AR) and their joint effect on early triple-negative breast cancer (TNBC) prognosis. Analyzes to date evaluated mostly stromal TIL (sTIL) and intratumoral (iTIL), but not separately in central tumor (CT) and invasive margin (IM). Methods: We retrospectively analyzed consecutive sample of 152 early TNBC patients treated at our institution 2009-2012. TIL and AR were assessed using standard FFPE samples, TIL according to International Working Group for Evaluation of TIL recommendation, sTIL and iTIL in CT and IM, and AR by immunohistochemistry. Results: Median age was 58, 84% NOS, median T 2.2cm, 41% N+, 22%, 59% and 19% in stage I, II and III, respectively. Radical mastectomy was performed in 39%, adjuvant chemotherapy in 88% and radiotherapy in 74% of patients. Positive AR defined as ≥1% nuclear-stained cells, were expressed in 31%, and AR≥10% in 26% of patients. Median TIL content was: sTIL 19%, iTIL 5%, TIL in CT 5%, at IM 18%, sTIL in CT (CTs) 5%, iTIL in CT (CTi) 1%, sTIL at IM (IMs) 30%, and iTIL at IM (IMi) 5%. Prevalence of intermediate or high TIL content, defined as ≥10% was: CTs in 48%, CTi in 23%, IMs in 86%, and IMi in 47% of cases. In bivariable analysis all TIL indicators were significantly associated with longer OS, while AR was not. After adjustment for potential confounders using Cox proportional hazard regression, significant predictors of OS were sTIL (p0.007), IM TIL (p0.002), IMs (p0.001), and IMi (p0.030). In all cases higher TIL content was associated with longer OS. Although AR was not significant predictor of OS, it's interactions with TIL IMs and IMi was. There was no significant difference in OS between patients with high IMs and low IMs and AR0, but those with high IMs and AR≥1 had HR0.22 (p0.045) for death compared to patients with low IMs and AR0. Also, no difference for high IMi and low IMi and AR0, but patients with high IMi and AR≥1 had HR0.10 (p0.028) for death compared to patients with low IMi and AR0. Conclusions: Section analysis reveals frequent intermediate to high density and statistically significant prognostic impact of TIL on IM. That directs question towards role of different tumor compartments. Furthermore, combination of high expression of IMs and IMi with AR≥1 appears to be associated with longer OS than in patients with high IMs and IMi but with AR0. The correlations between AR and all TIL studied are extremely small, indicating their independence, but if so, their interaction in impact on OS is particularly interesting.

Possible predictive role of cancer/testis antigens in breast ductal carcinoma in situ

Cancer/testis antigens (CTAs) are a large family of tumor-associated antigens expressed in human tumors of different histological origin, but not in normal tissues, with the exception of the testes and placenta. Numerous immunohistochemical studies have reported associations between CTA expression and a negative estrogen receptor (ER) status in breast tumors, and demonstrated that CTAs are frequently expressed in tumors with higher nuclear grade. The expression of CTAs has not been studied as extensively in ductal carcinoma in situ (DCIS) as it has been in invasive breast cancer. The present retrospective study included archived paraffin-embedded specimens from 83 patients diagnosed with DCIS in the period between January 2007 and December 2014. The follow-up time for local recurrence ranged between 1 and 8 years (mean, 5.02 years). Antigens from the melanoma-associated antigen gene (MAGE) family, namely multi-MAGE-A, MAGE-A1, MAGE-A10 and New York esophageal squamous cell carcinoma 1 (NY-ESO-1) antigen, were evaluated by immunostaining and their subcellular location was investigated. Presence of tumor-infiltrating lymphocytes (TILs) was evaluated on all sections, together with the histopathological variables of DCIS. Specific tested antigens exhibited associations with histopathological parameters for DCIS and all demonstrated statistically significant associations with nuclear staining, simultaneous cytoplasmic and nuclear staining, and local recurrence. Antigen MAGE-A10 demonstrated a significant association with higher expression of ER (P=0.005) and higher tumor nuclear grade (P=0.001), cytoplasmic staining (P=0.029) and antigen NY-ESO-1 with higher tumor size (P=0.001), expression of TILs (P=0.001) and R1 resection (P=0.001). A χ² test revealed significant associations between simultaneous cytoplasmic and nuclear staining and local recurrence (P=0.005), central necrosis (P=0.016), and the expression of ER (P=0.003) and progesterone receptor (PR) (P=0.010). Additional analysis revealed an association between antigen MAGE-A10 and TILs (P=0.05). Additional analysis of TILs indicated that they were significantly associated with tumor grade (P=0.023), central necrosis (P<0.001), ER (P=0.003) and PR (P=0.029). Overall, CTAs from the MAGE family (MAGE-A1, multi-MAGE-A and MAGE-A10) and NY-ESO-1 associate with histopathological predictive variables of DCIS. The expression of antigens NY-ESO-1 and MAGE-A10 could serve an important role in the treatment of patients with negative histopathological predictive variables, but further analysis is required. Simultaneous cytoplasmic and nuclear protein expression of MAGE-A family and NY-ESO-1 CTAs may represent an independent marker for local recurrence. Taken together, the present data suggest that CTAs are not perfect indicators of invasiveness for DCIS, but could inform treatment strategies for patients when taken in combination with other histopathological predictive variables. However, this was a small study and further larger studies will be necessary to confirm the current findings.

Apoptosis regulator Bcl-2 is an independent prognostic marker for worse overall survival in triple-negative breast cancer patients

BACKGROUND

The objective of this study was to examine the prognostic significance of carbonic anhydrase IX (CAIX), an endogenous marker for tumor hypoxia; the cellular tumor antigen p53; and the apoptosis regulator Bcl-2, in triple-negative breast cancer (TNBC) patients.

METHODS

Immunohistochemically determined expression of CAIX, p53, Bcl-2 and proliferation factor Ki-67, analyzed in 64 paraffin-embedded TNBC tissue samples, was used to assess their relation to clinicopathological variables and prognostic implications for overall survival (OS).

RESULTS

Bcl-2 expression was negatively correlated with histological grade of tumor, while expression of p53 was positively correlated with the same clinical variable (p = 0.036 and p = 0.033, respectively). The p53 expression was also positively correlated with tumor size (p = 0.010). Survival analysis showed that patients with high Bcl-2 expression (above cutoff value determined by receiver operator characteristic [ROC] curve analysis) had shorter OS (p = 0.020). The same was observed for patients with tumors larger than 5 cm (p = 0.034) or positive lymph nodes (p = 0.004). Among all 3 examined markers, multivariate analysis showed that only Bcl-2 expression was a strong independent prognostic indicator for decreased OS (hazard ratio [HR] = 15.16, 95% confidence interval [95% CI], 2.881-79.727, p = 0.001).

CONCLUSIONS

Elevated expression of Bcl-2 was an independent prognostic factor for poorer OS in TNBC and as such a significant marker for tumor aggressiveness.

Expression of nm23-H1 and COX-2 in thyroid papillary carcinoma and microcarcinoma

The expression of non-metastatic expressed/non-metastatic 23 nucleoside diphosphate kinase 1 (nm23-H1) and cyclooxygenase 2 (COX-2) proteins in thyroid carcinoma have been analysed in a number of previous studies, but this requires further study. The current study focused on the expression levels of nm23-H1 and COX-2 in 130 human thyroid papillary carcinoma (PTC) tissues. Of the 130 PTC tissues, 55 were classified as microcarcinoma and may provide information on the development of the specific characteristics of this tumour type. Routine histopathological examination and immunohistochemical detection of nm23-H1 and COX-2 expression was performed on 130 PTC tissues from patients treated in the Clinical Hospital for Tumours (Zagreb, Croatia) between January 2000 and December 2007. The stain intensity of nm23-H1 and COX-2 proteins was compared with the characteristics of the patients and the tumour. The highest overall expression rate of nm23-H1 and COX-2 was 90 and 67.6%, respectively, and the joint expression of these proteins was statistically significant. The median expression level of nm23-H1 was significantly increased in the classical and follicular histological group of the PTC tissues compared with tissues from other histological groups. The median expression level of COX-2 was significantly increased in the follicular histological group, and reduced in the diffuse-sclerosing group of PTC tissues. All the metastatic microcarcinoma tissues had increased expression levels of the two proteins in comparison with microcarcinoma tissues without lymph node metastases; however, this variation was only statistically significant for COX-2 expression levels. Therefore the results of the current study indicate that COX-2 protein levels may be able to differentiate which thyroid papillary microcarcinoma tumours possess metastatic potential.

The prognostic significance of estrogen receptor β in head and neck squamous cell carcinoma

Head and neck squamous cell carcinoma (HNSCC) is the fifth most common cancer in the world. Although multimodal and targeted therapy is now used in therapeutic procedures, the survival of patients with HNSCC has remained unchanged over the last 30 years. A number of studies have demonstrated that the increased expression of intranuclear ERβ in breast, lung and colon cancer is a favorable prognostic marker associated with higher survival rates. However, the clinical significance of sex hormone receptors in HNSCC remains unclear. The current study aimed to assess the expression of ERβ in HNSCC immunohistochemically and investigate any possible association between ERβ expression, and clinical and histopathological factors, disease recurrence and patient survival. The present study included 174 patients (165 males and 9 females) with a median age of 60.8 years (range, 39–79) with HNSCC who were primary surgically treated between January 2000 and December 2006. Immunohistochemical reactions for ERβ demonstrated that 73 patients (42%) exhibited positive ERβ expression. Distribution of ERβ status among different head and neck subsites indicated that >40% of all negative cases were located in laryngeal primaries, while incidence of other sublocalization within positive cases was similar and comparable (P=0.04). Furthermore, a correlation was observed between ERβ immunopositivity and the survival of patients, with respect to the primary tumor site. Patients with ERβ positive oropharyngeal cancer had a survival rate of 35.3% at 5-years compared with 25% for patients with negative expression. However, ERβ status was not significantly correlated with any other clinical or histopathological parameter. After an average follow-up time of 38.5 months (range, 3–60 months), 54 patients (31.1%) had succumbed to disease recurrence while 50 (28.7%) succumbed to other causes. In conclusion, ERβ positivity indicates improved survival of patients with oropharyngeal cancer. Further research is required in order to implement novel therapeutic strategies.

Obstructive Jaundice as an Uncommon Manifestation of Metastatic Breast Cancer

Invasive ductal carcinoma is the most common type of breast cancer and accounts for about 70-85% of all invasive breast carcinomas. It primarily metastasizes to the bone, lungs, regional lymph nodes, liver and brain. Most of breast cancer recurrence occurs within the first 5 years of diagnosis, particularly for ER negative disease. Gastrointestinal tract involvement is very rare and is detected in only 10% of all the cases, and it usually derives from lobular breast cancer rather than the much more common cell type of ductal breast cancer. Early diagnosis is very important because it enables prompt and adequate choice of treatment and improves patient’s long-term prognosis. In this report we describe an unusual case of obstructive jaundice caused by metastases from invasive ductal breast cancer to the lymph nodes of the hepatoduodenal ligament with extramural compression of the distal common bile duct and tumor invasion to the lumen of the duct. Our goal is to emphasize possible diagnostic pitfalls and increase the clinical awareness and the importance of intensive follow-up in patients with breast cancer, even years after the initial diagnosis.

Expression of nm23-h1 gene in squamous-cell carcinoma of the cervix correlates with 5-year survival

We have examined nm23-H1 protein levels in human squamous cell carcinoma of the cervix by immunohistochemistry and correlated detectable nm23-H1 with patient survival. Normal cervical tissue samples were consistently strongly immunoreactive. In contrast, cervical carcinomas stained poorly, if at all. Well differentiated carcinomas stained more frequently for nm23-H1 protein than poorly or undifferentiated carcinomas. Our results clearly demonstrated a significant correlation between absence of nm23-H1 protein staining and shorter survival of patients with cervical cancer. Our results suggest that nm23 may serve as a potentially valuable prognostic marker for this type of tumor and to our knowledge is the first report of this kind for cervical carcinoma.

Prognostic significance of carbonic anhydrase IX (CA-IX), endoglin (CD105) and 8-hydroxy-2'-deoxyguanosine (8-OHdG) in breast cancer patients

The aim of this study was to examine the prognostic significance of carbonic anhydrase IX (CA-IX), an endogenous marker for tumor hypoxia; endoglin (CD105), a proliferation-associated and hypoxia-inducible glycoprotein and 8-hydroxy-2'-deoxyguanosine (8-OHdG), an oxidative DNA lesion, in breast cancer patients. Immunohistochemical expressions of CA-IX, CD105 and 8-OHdG, analyzed on paraffin-embedded tumor tissues from forty female breast cancer patients, were used to assess their prognostic implication on overall survival (OS) and relapse-free survival (RFS). Patients with high CA-IX expression (above cut-off value) had a higher occurrence of relapse (P = = 0.002). High CA-IX expression was significantly associated with shorter RFS (P < 0.001, hazard ratio (HR) 0.21) and shorter OS (P < 0.001, HR 0.19). Lymph node negative patients with high CA-IX expression had worse RFS (P = 0.031, HR 0.14) and OS (P = 0.005, HR 0.05). Patients with grade I&II tumors and high CA-IX expression showed shorter RFS (P = 0.028, HR 0.28) and OS (P = 0.008, HR 0.20). Worse OS (P = 0.046, HR 0.28) was found in subgroup of patients with grade II tumors and high CA-IX expression. Among all three markers, only high CA-IX expression was strong independent prognostic indicator for shorter OS (HR 4.14, 95% CI 1.28-13.35, P = 0.018) and shorter RFS (HR 3.99, 95% CI 1.38-11.59, P = 0.011). Elevated expression of CA-IX was an independent prognostic factor for decreased RFS and OS and a significant marker for tumor aggressiveness. CD105 had week prognostic value; whereas, 8-OHdG, in this study, did not provide sufficient evidence as a prognostic indicator in breast cancer patients.

Prognostic value of MAGE-A and NY-ESO-1 expression in pharyngeal cancer

BACKGROUND

The prognostic value of cancer testis antigens in pharyngeal cancer is understudied.

METHODS

We recruited 90 patients who were treated for pharyngeal cancer. Monoclonal antibodies 57B and B9.8.1.1 were used for detection of MAGE-A and NY-ESO-1 genes.

RESULTS

MAGE-A and NY-ESO-1 gene products were detectable in 70.0% and 33.3% of pharyngeal tumors, respectively. No correlation was established between MAGE-A and NY-ESO-1 expression and TNM staging at presentation. Survival analysis showed a trend toward a shorter 5-year disease-free survival in the group of patients with MAGE-A-positive tumors (log-rank test, p = .122). In contrast, a trend toward a prolonged 5-year disease-free survival was observed in the group of patients with NY-ESO-1-positive tumors (log-rank test, p = .219).

CONCLUSION

In a large population of patients with pharyngeal cancer and available 5-year survival data, prognosis tended to be poorer with MAGE-A expression and better with NY-ESO-1 expression, but the correlations did not reach statistical significance.

Expression of MAGE tumor-associated antigen in thyroid carcinomas

The 12 members of the MAGE gene family encode tumor-specific antigens that are recognized by autologous cytotoxic T lymphocytes. The MAGE genes are expressed not only in melanoma but in other malignant tumors as well. There is, however, little information on their expression in thyroid carcinomas. We studied the expression of the MAGE-3 antigen in human thyroid carcinomas to explore the possibility of specific immunotherapy using MAGE peptides. Tumor tissue samples of thyroid carcinomas were obtained from 60 patients. Standard pathohistologic analysis followed by immunohistochemistry analysis of MAGE-3 expression was performed in all patients. The overall expression rate of MAGE-3 antigen in thyroid carcinomas was 65%. According to histological types of thyroid carcinomas, expression rate of MAGE-3 antigen was as follows: 0% in anaplastic, 20% in medullary, 29% in follicular, and 80% in papillary thyroid carcinomas (p < 0.01). On the other hand, significantly higher expression of MAGE-3 antigen was observed in classical subtypes of papillary thyroid carcinomas and in small papillary tumors sized to 1 cm in diameter. These findings demonstrated that MAGE-3 antigen expression seems to be particularly high in the small, typical papillary carcinomas, thus suggesting that MAGE-3 gene abnormality is an early step in thyroid cancer progression.

Expression of cancer/testis tumor associated antigens in cervical squamous cell carcinoma

We investigated the expression of tumor-associated antigens (TAA) of the cancer/testis (C/T) gene family in cervical squamous cell carcinomas. First, we focused on the HeLa cervical cancer derived cell line, and we found that it expresses MAGE-A1, MAGE-A2, MAGE-A3, MAGE-A4, MAGE-A6, MAGE-A12, GAGE-3/6, LAGE-1, and PRAME genes, encoding defined C/T TAA. In contrast, no expression of MAGE-A10, BAGE, GAGE-1/2, or NY-ESO-1 genes was observed. Corresponding gene products could also be detected by immunoblotting and immunocytochemistry, taking advantage of monoclonal antibodies recognizing discrete TAA. Capitalizing on these data, a monoclonal antibody predominantly recognizing MAGE-A4 TAA in paraffin-embedded sections (57B) was used to investigate the C/T gene expression in clinical tumor samples. A group of 60 patients was studied, and 57B positivity was detectable to different extents in 33% of the cases (20/60). In 13 of them (21%), staining of over 50% of the tumor cells was evident, whereas healthy cells always scored negative. Remarkably, MAGE-A4 expression was significantly (p < 0.05) more frequently detectable in poorly differentiated tumors (8/13) than in well-differentiated or moderately differentiated cancers (3/15 and 9/32, respectively) and in stage FIGO II as compared with stage FIGO Ib tumors (12/23 and 5/24, respectively, p = 0.04). Interestingly, staining was mostly nuclear in well-differentiated tumors, but involved both nuclei and cytoplasm in less differentiated cancers. Positivities of comparable frequency were also detectable in a smaller series of specimens upon staining with MAGE-A1- or NY-ESO-1/LAGE-1-specific reagents. Considering the high tumor specificity of C/T TAA, our data provide the rationale for the design of immunotherapy procedures targeting these antigens in cervical cancers.

Cancer/testis tumour-associated antigens: immunohistochemical detection with monoclonal antibodies

Cancer/testis tumour-associated antigens (C/T TAA) were the first human tumour-associated antigens to be characterised at the molecular level. Specific genes are expressed in the testis and in tumours of varying histological origin. The tissue expression pattern supports the notion that these antigens could be targets for active specific immunotherapy. Specific serological reagents have been developed and have helped to clarify biochemical characteristics of C/T TAA and to assess their distribution within clinical tumour samples. We review immunohistochemical evidence of the expression of C/T TAA known to be recognised by specific cytotoxic T lymphocytes. The emerging picture is consistent with a mostly heterogeneous expression in human cancers. These findings support the concept of multiantigenic tumour vaccine preparations. Moreover, the wide range of tumours in which C/T TAA have been detected urges further efforts to develop effective specific immunotherapeutic procedures.

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.

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.

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.

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.

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.

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.

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.

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.

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.

Purification and characterization of a mitogen-activated protein kinase tyrosine phosphatase from Xenopus eggs

The mitogen-activated protein (MAP) kinases are serine-threonine protein kinases that are activated by tyrosine and threonine phosphorylation by the dual specificity protein kinase MEK (MAP kinase/ERK kinase). The present report describes the purification to near homogeneity and characterization of a protein tyrosine phosphatase from Xenopus laevis eggs that dephosphorylates MAP kinase phosphorylated by MEK. Bacterially expressed Xenopus MAP kinase phosphorylated by purified Xenopus MEK was used as substrate throughout the purification. The purification procedure included anion-exchange, cation-exchange, gel filtration, heparin-Sepharose, and chromatography on a column of thiophosphorylated MAP kinase-Sepharose, resulting in a > 3000-fold purification. Upon analysis by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, a protein of 47 kDa correlated with activity. The phosphatase showed absolute specificity toward phosphotyrosine and no activity toward phosphothreonyl-phosphoseryl residues of MAP kinase. The pH optimum of the enzyme was 7.0 with a Km of 9.0 microM for phosphorylated MAP kinase. The phosphatase was inhibited by ammonium molybdate (IC50, 2 microM), vanadate (IC50, 250 microM), millimolar concentrations of MnCl2, ZnCl2 and p-nitrophenylphosphate but not by okadaic acid or microcystin. This tyrosine phosphatase may be involved in deactivating MAP kinase in vivo.

Induction of metaphase arrest in cleaving Xenopus embryos by MAP kinase

The natural arrest of vertebrate unfertilized eggs in second meiotic metaphase results from the activity of cytostatic factor (CSF). The product of the c-mos(xe) proto-oncogene is thought to be a component of CSF and can induce metaphase arrest when injected into blastomeres of two-cell embryos. The c-Mos(xe) protein can directly activate the mitogen-activated protein kinase kinase (MAP kinase kinase) in vitro, leading to activation of MAP kinase. MAP kinase and c-Mos(xe) are active in unfertilized eggs and are rapidly inactivated after fertilization. Microinjection of thiophosphorylated MAP kinase into one blastomere of a two-cell embryo induced metaphase arrest similar to that induced by c-Mos(xe). However, only arrest with c-Mos(xe) was associated with activation of endogenous MAP kinase. These results indicate that active MAP kinase is a component of CSF in Xenopus and suggest that the CSF activity of c-Mos(xe) is mediated by MAP kinase.

The smooth muscle 132 kDa cyclic GMP-dependent protein kinase substrate is not myosin light chain kinase or caldesmon

Atrial natriuretic peptide (ANP) stimulates the phosphorylation of three cyclic GMP-dependent protein kinase substrate proteins of 225, 132, and 11 kDa (P225, P132 and P11 respectively) in the particulate fraction of cultured rat aortic smooth muscle cells [Sarcevic, Brookes, Martin, Kemp & Robinson (1989) J. Biol. Chem. 264, 20648-20654]. Vrolix, Raeymaekers, Wuytack, Hofmann & Casteels [(1988) Biochem. J. 255, 855-863] have reported the presence of a 130 kDa cyclic GMP-dependent protein kinase substrate protein in the membrane fraction of pig aorta or stomach, and suggested that it may be myosin light chain kinase (MLCK). The aim of the present study was to determine whether P132 from rat aorta was MLCK or caldesmon. Although P132 co-migrates with purified chicken gizzard MLCK on SDS/polyacrylamide gels, it is distinct from rat aortic MLCK. Partially purified MLCK from rat aorta migrated as a 145 kDa protein on SDS/polyacrylamide gels. Immunoblotting the partially purified rat aortic MLCK with antibody to bovine tracheal MLCK identified rat aortic MLCK (145 kDa) and a corresponding 145 kDa protein in the particulate fraction of cultured rat aortic smooth muscle cells, but did not detect the 132 kDa protein. Phosphopeptide maps of purified rat aortic MLCK prepared by digestion with Staphylococcus aureus V8 protease were distinct from those of P132. P132 was not caldesmon, since antibodies to caldesmon cross-reacted with 136 and 76 kDa proteins in the particulate fraction of rat aortic cells, but not with P132. Furthermore, caldesmon was partially extracted from the particulate into the soluble fraction by heating at 90 degrees C, whereas P132 was not. These results demonstrate that the ANP-responsive cyclic GMP-dependent protein kinase substrate of 132 kDa from rat aortic smooth muscle cells is not MLCK or caldesmon.

Atrial natriuretic peptide-dependent phosphorylation of smooth muscle cell particulate fraction proteins is mediated by cGMP-dependent protein kinase

The atrial natriuretic peptide (ANP) stimulates cGMP production and protein phosphorylation in a particulate fraction of cultured rat aortic smooth muscle cells. Three proteins of 225, 132, and 11 kDa were specifically phosphorylated in response to ANP treatment, addition of cGMP (5 nM), or addition of purified cGMP-dependent protein kinase. The cAMP-dependent protein kinase inhibitor had no effect on the cGMP-stimulated phosphorylation of the three proteins but inhibited cAMP-dependent phosphorylation of a 17-kDa protein. These results demonstrate that the particulate cGMP-dependent protein kinase mediates the phosphorylation of the 225-, 132-, and 11-kDa proteins. The 11-kDa protein is phospholamban based on the characteristic shift in apparent Mr from 11,000 to 27,000 on heating at 37 degrees C rather than boiling prior to electrophoresis. ANP (1 microM) increased the cGMP concentration approximately 4-fold in the particulate fractions, from 4.3 to 17.7 nM, as well as the phosphorylation of the 225-, 132-, and 11-kDa proteins. In contrast, the biologically inactive form of ANP, carboxymethylated ANP (1 microM), did not stimulate phosphorylation of any proteins nor did the unrelated peptide hormone, angiotensin II (1 microM). These results demonstrate the presence of the cGMP-mediated ANP signal transduction pathway in a particulate fraction of smooth muscle cells and the specific phosphorylation of three proteins including phospholamban, which may be involved in ANP-dependent relaxation of smooth muscle.