The p53 tumor suppressor gene in breast cancer

Isolation and characterization of N-(2-Hydroxyethyl)hexadecanamide from Colletotrichum gloeosporioides with apoptosis-inducing potential in breast cancer cells

Endophytic fungi are a well-established reservoir of bioactive compounds that are pharmaceutically valuable and therefore, contribute significantly to the biomedical field. The present study aims to identify the bioactive anticancer compound from ethyl acetate extract of fungal endophyte, Colletotrichum gloeosporioides associated with the leaf of the medicinal plant Oroxylum indicum. The fatty acid amide compound N-(2-Hydroxyethyl)hexadecanamide (Palmitoylethanolamide; PEA) was identified using antioxidant activity-guided fractionation assisted with tandem liquid chromatography coupled with quadrupole time of flight mass spectrometry, Fourier transform-infrared spectroscopy, time-of-flight mass spectrometry, and nuclear magnetic resonance. In-Silico molecular docking analysis showed that PEA potentially docked to the active sites of apoptosis-inducing proteins including BAX, BCL-2, P21, and P53. Further validation was done using in vitro study that showed PEA inhibitsthe proliferation, alters nuclear morphology and attenuates the wound closure ability of MDA-MB-231 and MCF-7 cells. PEA induces apoptosis via upregulating cell-cycle arrest (P21), tumor suppression (P53), pro-apoptotic (BAX, CASPASE-8, and FADD) genes, and downregulating anti-apoptotic gene BCL-2. The upregulation of the active form of Caspase-3 was also reported. This is the first-ever report for the isolation of PEA from C. gloeosporioides with anticancer activity against human breast cancer cells and therefore holds great potential for future therapeutics.

TNFα Enhances Tamoxifen Sensitivity through Dissociation of ERα-p53-NCOR1 Complexes in ERα-Positive Breast Cancer

Simple Summary

Tamoxifen has been clinically applied as a central chemotherapeutic agent for treatment of estrogen receptor (ER)-positive breast cancer. However, many ER-positive breast cancer patients with the high ER level demonstrate intrinsic resistance against the tamoxifen therapy. The aim of our study was to find an effective approach to enhance tamoxifen sensitivity. We found that tumor necrosis factor α (TNFα) has a potential to overcome tamoxifen resistance through disruption of nuclear receptor corepressor 1 (NCOR1)-p53-ERα complexes in ER-positive MCF7 xenograft mice. NCOR1 knock-down with TNFα treatment induced ERα destabilization and increased the occupancy of p53 at the p21 promoter. Finally, we confirmed the combinational application with tamoxifen, TNFα and short-hairpin NCOR1 showed the enhanced suppressive effect of tumor growth in MCF xenograft mice compared to single tamoxifen treatment. These results provide a possibility for application of NCOR1 as a putative therapeutic target to overcome tamoxifen resistance in ERα-positive breast cancer.

Abstract

Tamoxifen is widely used as a medication for estrogen receptor α (ERα)-positive breast cancer, despite the ~50% incidence of tamoxifen resistance. To overcome such resistance, combining tamoxifen with other agents is considered an effective approach. Here, through in vitro studies with ER-positive MCF7 cells and ER-negative MDA-MB-231 cells, validated by the use of xenograft mice, we investigated the potential of tumor necrosis factor α (TNFα) to enhance tamoxifen sensitivity and identified NCOR1 as a key downstream regulator. TNFα specifically degraded nuclear receptor corepressor 1 (NCOR1) in MCF7 cells. Moreover, knockdown of NCOR1, similar to TNFα treatment, suppressed cancer cell growth and promoted apoptosis only in MCF7 cells and MCF7 xenograft mice through the stabilization of p53, a tumor suppressor protein. Interestingly, NCOR1 knockdown with TNFα treatment increased the occupancy of p53 at the p21 promoter, while decreasing that of ERα. Notably, NCOR1 formed a complex with p53 and ERα, which was disrupted by TNFα. Finally, combinatorial treatment with tamoxifen, TNFα and short–hairpin (sh)-NCOR1 resulted in enhanced suppression of tumor growth in MCF7 xenograft mice compared to single tamoxifen treatment. In conclusion, TNFα promoted tamoxifen sensitivity through the dissociation of the ERα-p53-NCOR1 complex, pointing at NCOR1 as a putative therapeutic target for overcoming tamoxifen resistance in ERα-positive breast cancer.

The Prognostic Value of p53 and c-erbB-2 Expression, Proliferative Activity and Angiogenesis in Node-Negative Breast Carcinoma

Aims and background

p53, c-erbB-2 and Ki-67 protein expression and microvessel density (MVD) determined by CD34 antibody were evaluated by immunohistochemistry and their correlation with clinicopathological parameters including estrogen (ER) and progesterone (PR) receptor status and survival were investigated in patients with axillary lymph node-negative infiltrating ductal breast carcinoma.

Methods

The study population consisted of 47 patients with axillary lymph node-negative infiltrating ductal breast carcinoma.

Results

p53 and c-erbB-2 expression was detected in 36.2% and 31.9% of patients, respectively. Median Ki-67 expression was 10%. There were no statistically significant differences in the distribution of p53, Ki-67 and c-erbB-2 protein expression in relation to the age of the patients or to the size, histological grade or ER and PR status of the tumors. p53 protein expression correlated positively with c-erbB-2 and Ki-67 protein expression (P <0.05). The mean MVD was 63.65 ± 29.1 and it correlated positively with histological grade and Ki-67 expression (P <0.05). Survival analysis revealed that age, tumor size, p53 and c-erbB-2 expression and PR status had no significant prognostic impact, whereas histological grade, proliferative activity and angiogenic activity were significant prognostic factors. Although ER-positive patients had a statistically significant overall survival advantage, the difference in disease-free survival was not significant.

Conclusion

In axillary lymph node-negative breast carcinoma the histological grade and the proliferative and angiogenic activity of the tumor could be useful prognostic indicators.

p53 and Breast Cancer

Inactivation of the p53 tumor suppressor gene is one of the commonest genetic changes identified in human breast cancer. In this review, the structure and function of the p53 gene and its protein products will be discussed, with particular reference to p53 alterations that contribute to carcinogenesis. The frequency and pattern of p53 alterations in breast cancer will be outlined, laboratory methods for their detection briefly summarized, and the potential use of p53 as a prognostic and predictive marker discussed.

Mutations in Human Interferon α2b Gene and Potential as Risk Factor Associated with Female Breast Cancer

The current study explored the potential links between breast cancer and human interferon α-2b (hIFNα-2b) gene mutations. The hIFNα-2b gene was amplified from breast cancer tumor tissue samples (N = 60) by polymerase chain reaction (PCR) and the products were subjected to gene sequencing. A total of 38 (63.3%) samples showed positive PCR amplification results. Several of these also exhibited frequent alterations (mutations) after 400 bp and, in particular, adenine was replaced by other bases. A total of 19 selected mutated amino acids were analyzed for local/general fold pattern changes. Human IFNα-2b receptor (IFNAR): ligand (hIFNα-2b protein) interactions through a Z-DOCK (3.0.2) server were also evaluated to assess the binding patterns of each ligand to receptor to induce Janus-Kinase-signal transducer and activator of transcription antiproliferative signal transduction pathway inside the cancer cells. Certain local structural and conformational changes were predicted to be induced by mutations in the ligand. The variant models of the hIFNα-2b displayed structural and conformational changes that signified that changes to hIFNα-2b may be a risk factor in addition to other known factors associated with onset/progression of female breast carcinoma. It was hoped that others might build upon the research in this study evaluating protein structural models with mutations and their consequent interactions with receptors in the development of potent immune therapeutic drugs for breast cancer that are based on recombinant hIFNα-2b.

Prevalence of HER-2 and Hormone Receptors and P53 Mutations in the Pathologic Specimens of Breast Cancer Patients

Prognostic factors are in interest for breast cancer as the second cause of malignancy deaths. Some have predictive values as human epidermal growth factor receptor-2 (HER-2) and estrogen receptor (ER). To access the incidence of HER2 and its relations to other factors, like age, pathology, ER, progesterone receptor (PR), and P53, 2000 pathologic blocks from 2750 total samples have been selected from 2011 to 2013 in Cancer Institute of Tehran. Incidence of HER2, ER, PR, and P53 was; 58.5%, 33.4%, 43.3%, and 65.4%, respectively. Invasive ductal carcinoma was the most pathologic type (82.2%) and 60%-70% positive HER2 and P53 had negative ER and PR (poor prognosis). The peak age of incidence of breast cancer was perimenopausal age group (46-55 years). Our cases had more positive HER2 and P53 and less positive PR and ER compared to other studies. High perimenopausal incidence as another finding assures the importance of breast cancer screening in these age groups.

Apocrine-eccrine carcinomas: molecular and immunohistochemical analyses

Apocrine-eccrine carcinomas are rare and associated with poor prognosis. Currently there is no uniform treatment guideline. Chemotherapeutic drugs that selectively target cancer-promoting pathways may complement conventional therapeutic approaches. However, studies on genetic alterations and EGFR and Her2 status of apocrine-eccrine carcinomas are few in number. In addition, hormonal studies have not been comprehensive and performed only on certain subsets of apocrine-eccrine carcinomas. To investigate whether apocrine-eccrine carcinomas express hormonal receptors or possess activation of oncogenic pathways that can be targeted by available chemotherapeutic agent we performed immunohistochemistry for AR, PR, ER, EGFR, and HER2 expression; fluorescence in situ hybridization (FISH) for EGFR and ERBB2 gene amplification; and molecular analyses for recurrent mutations in 15 cancer genes including AKT-1, EGFR, PIK3CA, and TP53 on 54 cases of apocrine-eccrine carcinomas. They include 10 apocrine carcinomas, 7 eccrine carcinomas, 9 aggressive digital papillary adenocarcinomas, 10 hidradenocarcinomas, 11 porocarcinomas, 1 adenoid cystic carcinoma, 4 malignant chondroid syringomas, 1 malignant spiradenoma, and 1 malignant cylindroma. AR, ER, PR, EGFR and HER2 expression was seen in 36% (19/53), 27% (14/51), 16% (8/51), 85% (44/52) and 12% (6/52), respectively. Polysomy or trisomy of EGFR was detected by FISH in 30% (14/46). Mutations of AKT-1, PIK3CA, and TP53 were detected in 1, 3, and 7 cases, respectively (11/47, 23%). Additional investigation regarding the potential treatment of rare cases of apocrine-eccrine carcinomas with PI3K/Akt/mTOR pathway inhibitors, currently in clinical testing, may be of clinical interest.

The gain of function of p53 cancer mutant in promoting mammary tumorigenesis

Tumor suppressor p53 is critical for suppressing all types of human cancers, including breast cancer. The p53 gene is somatically mutated in over half of all human cancers. The majority of the p53 mutations are missense mutations, leading to the expression of the full-length p53 mutants. Several hotspot mutations, including R175H, are frequently detected in human breast cancer. P53 cancer mutants not only lose tumor suppression activity but, more problematically, also gain new oncogenic activities. Despite correlation of the expression of p53 cancer mutants and the poor prognosis of human breast cancer patients, the roles of p53 cancer mutants in promoting breast cancer remain unclear. We used the humanized p53 cancer mutant knock-in (R175H) mice and mouse mammary tumor virus (MMTV)-Wnt-1 transgenic (mWnt-1) mice to specifically address the gain of function of R175H in promoting breast cancer. Although both R175H/R175HmWnt-1(R175HmWnt-1) and p53(-/-)mWnt-1 mice died from mammary tumor at the same kinetics, which was much earlier than mWnt-1 mice, most of the R175HmWnt-1 mice developed multiple mammary tumors per mouse, whereas p53(-/-)mWnt-1 and mWnt-1 mice mostly developed one tumor per mouse. The multiple mammary tumors arose in the same R175HmWnt-1 mouse exhibited different histological characters. Moreover, R175H gain-of-function mutant expands the mammary epithelial stem cells (MESCs) that give rise to the mammary tumors. As ATM suppresses the expansion of MESCs, the inactivation of ATM by R175H in mammary epithelial cells (MECs) could contribute to the expansion of MESCs in R175HmWnt-1 mice. These findings provide the basis for R175H to promote the initiation of breast cancer by expanding MESCs.

Assessing estrogen signaling aberrations in breast cancer risk using genetically engineered mouse models

Aberrations in estrogen signaling increase breast cancer risk. Molecular mechanisms that impact breast cancer initiation, promotion, and progression can be investigated using genetically engineered mouse models. Increasing estrogen receptor alpha (ERα) expression levels twofold is sufficient to initiate and promote breast cancer progression. Initiation and promotion can be increased by p53 haploinsufficiency and by coexpressing the nuclear coactivators amplified in breast cancer 1 (AIB1) or the splice variant AIB1Δ3. Progression to invasive cancer is found with coexpression of these nuclear coactivators as well as following a single dose of 7,12-dimethylbenz(a)anthracene. Loss of signal transducer and activator of transcription 5a reduces the prevalence of initiation and promotion but does not protect from invasive cancer development. Cyclin D1 loss completely interrupts mammary epithelial proliferation and survival when ERα is overexpressed. Loss of breast cancer gene 1 increases estrogen signaling and cooperates with ERα overexpression in initiation, promotion, and progression of mammary cancer.

p53 Expression in node-positive breast cancer patients: results from the Cancer and Leukemia Group B 9344 Trial (159905)

PURPOSE

p53 as a prognostic and predictive factor in early-stage breast cancer has had mixed results. We studied p53 protein expression, by immunohistochemistry, in a randomized clinical trial of stage II patients treated with adjuvant doxorubicin and cyclophosphamide with or without paclitaxel [Cancer and Leukemia Group B (CALGB) 9344, INT0148].

PATIENTS AND METHODS

Epithelial p53 expression was evaluated using two immunohistochemical antibodies (DO7 and 1801) in formalin-fixed, paraffin-embedded tissue from patients with node-positive breast cancer who were randomized to four cycles of cyclophosphamide and one of three doses of doxorubicin (60, 75, or 90 mg/m(2); AC) and to receive four subsequent cycles of paclitaxel (T) or not. Prognostic and predictive value of p53 protein expression was assessed, independent of treatment assignment, for escalating doses of doxorubicin or addition of T with endpoints of relapse-free (RFS) and overall survival (OS).

RESULTS

Of 3,121 patients, 1,887 patient specimens treated on C9344 were obtained, passed quality control, and evaluated for p53 expression. Expression was 23% and 27% for mAbs 1801 and D07, respectively, with 92% concordance. In univariate analysis, p53 positivity was associated with worse OS with either antibody, but only p53 staining with monoclonal antibody 1801 had significantly worse RFS. In multivariate analysis, p53 was not predictive of RFS or OS from either doxorubicin dose escalation or addition of paclitaxel regardless of the antibody.

CONCLUSION

Nuclear staining of p53 by immunohistochemistry is associated with worse prognosis in node-positive patients treated with adjuvant doxorubicin-based chemotherapy but is not a useful predictor of benefit from doxorubicin dose escalation or the addition of paclitaxel.

A potential role for targeted therapy in a subset of metastasizing adnexal carcinomas

Metastasizing adnexal carcinomas are rare; thus, currently there is no uniform treatment guideline. Chemotherapeutic drugs that selectively target cancer-promoting pathways may complement conventional therapeutic approaches. We performed immunohistochemistry (epidermal growth factor receptor (EGFR), HER2, and CD117), EGFR and ERBB2 fluorescence in situ hybridization (FISH), and multiplexed SNaPshot® genotyping (testing for recurrent mutations in 15 cancer genes including BRAF, EGFR, KRAS, PIK3CA, and TP53) on primary tumors and corresponding metastases of 14 metastasizing adnexal carcinomas (three apocrine, six eccrine, two hidradenocarcinomas, two porocarcinomas, and one aggressive digital papillary adenocarcinoma). Metastasis to regional lymph node was most common, followed by skin and then lungs. Follow-up was available in 12 patients (5 months to 8 years) with 1 died of widespread metastases. Although EGFR overexpression was a prevalent feature in this cohort, seen in 7/11 (64%) primary tumors and 10/14 (71%) metastases; FISH for EGFR gene amplification was negative in 9 tested primary tumors and 12 metastases. FISH of the one primary tumor and three metastases with 2+ HER2 overexpression revealed a low level of ERBB2 gene amplification in one apocrine carcinoma and corresponding metastasis. CD117 expression was seen only in rare cases. PIK3CA (2/12, 17%) and TP53 (3/12, 25%) mutations were detected in two (one hidradenocarcinoma, one porocarcinoma) and three (one eccrine, one hidradenocarcinoma, and one aggressive digital papillary adenocarcinoma) cases, respectively. The role of EGFR inhibitor therapy in metastasizing adnexal carcinomas with protein overexpression remains unclear. Targeted therapy including PI3K pathway inhibitors might be a potential treatment for rare cases of adnexal carcinomas with metastases.

Immunohistochemical analysis of prostate apoptosis response-4 (Par-4) in Mexican women with breast cancer: a preliminary study

BACKGROUND AND AIMS

We undertook this study to compare the expression level of prostate apoptosis response-4 (Par-4) among patient outcome in two groups of women with breast cancer (short and long survival) and two groups without breast cancer (benign lesion and control).

METHODS

We included breast specimens with nonhistological abnormalities (eight samples) as a control group. Semiquantitative and quantitative analysis of immunohistochemical staining by image analysis software were used to study the intensity of Par-4 expression. Both methods produced similar results (p>0.05).

RESULTS

No significant expression of Par-4 was observed in normal breast tissue. Benign lesions and breast cancer tissue showed strong nuclear expression of Par-4, predominantly on epithelial cells and specifically in ductal cells. Par-4 expression was lower in myoepithelial cells and there was no appreciable stromal staining. Significantly less Par-4 reactivity was detected in tissue from patients with a short survival compared with patients with benign lesions and those with a long survival.

CONCLUSIONS

Our findings suggest that a lower expression level of Par-4 is related to an unfavorable prognosis. A larger prospective study of samples of all patient groups with a longer follow-up is needed to validate this finding.

IFNgamma restores breast cancer sensitivity to fulvestrant by regulating STAT1, IFN regulatory factor 1, NF-kappaB, BCL2 family members, and signaling to caspase-dependent apoptosis

Antiestrogens are effective therapies for the management of many estrogen receptor-alpha (ER)-positive breast cancers. Nonetheless, both de novo and acquired resistance occur and remain major problems in the clinical setting. IFNgamma is an inflammatory cytokine that induces the expression and function of IFN regulatory factor 1 (IRF1), a tumor suppressor gene that can increase antiestrogen responsiveness. We show that IFNgamma, but not IFNalpha, IFNbeta, or fulvestrant (ICI; ICI 182,780; Faslodex), induces IRF1 expression in antiestrogen-resistant MCF7/LCC9 and LY2 cells. Moreover, IFNgamma restores the responsiveness of these cells to fulvestrant. Increased IRF1 activation suppresses NF-kappaB p65 (RELA) activity, inhibits the expression of prosurvival (BCL2, BCL-W), and induces the expression of proapoptotic members (BAK, mitochondrial BAX) of the BCL2 family. This molecular signaling is associated with the activation of signal transducer and activator of transcription 1 and leads to increased mitochondrial membrane permeability; activation of caspase-7 (CASP7), CASP8, and CASP9; and induction of apoptosis but not autophagy. Whereas antiestrogen-resistant cells are capable of inducing autophagy through IFN-mediated signaling, their ability to do so through antiestrogen-regulated signaling is lost. The abilities of IFNgamma to activate CASP8, induce apoptosis, and restore antiestrogen sensitivity are prevented by siRNA targeting IRF1, whereas transient overexpression of IRF1 mimics the effects of IFNgamma treatment. These observations support the exploration of clinical trials combining antiestrogens and compounds that can induce IRF1, such as IFNgamma, for the treatment of some ER-positive breast cancers.

Detection of P53 mutations in different cancer types is improved by cDNA sequencing

Recently published data show discrepancies between P53 cDNA and DNA sequencing results in glioblastoma, colorectal cancer and pleomorphic xanthoastrocytoma. We hypothesized that similar discrepancies are observed in other types of human cancers. Using DNA and cDNA direct sequencing, we analyzed 40 cases of invasive breast duct carcinoma, 23 cases of acute myeloblastic leukaemia, 12 cases of astrocytoma and 40 cases of soft tissue sarcoma for P53 mutations. Additionally, we used real-time quantitative PCR to estimate the normalized relative P53 expression. In the comparative study, the P53 mutation was detected more frequently when using cDNA sequencing than DNA sequencing in all of the cancer types. Furthermore, several samples presented missense P53 mutations, with visible wild-type nucleotide on the DNA sequence. In contrast, elimination of the wild-type allele or selective overproduction of the mutated allele was observed on the cDNA sequence. P53 expression was not significantly different between the cases with or without P53 mutations. These results indicate that cDNA sequencing improves the detection of P53 mutations in these cancers. We suggest that the true incidence of P53 mutations in these cancers is underestimated at the DNA level, and evaluation of the alteration should be carried out using cDNA analysis.

Deregulated estrogen receptor alpha and p53 heterozygosity collaborate in the development of mammary hyperplasia

Both increased estrogen receptor alpha (ER(alpha)) expression and germline disruption of one p53 allele increase breast cancer risk in women. Genetically engineered mouse models of deregulated ER(alpha) expression and p53 haploinsufficiency were used to investigate similarities and differences of each genetic lesion alone and in combination on mammary preneoplasia development. Each genetic lesion independently and in combination led to development of age-dependent preneoplasia, but the highest prevalence was found in compound mice with increased ER(alpha) expression coupled with p53 heterozygosity. All genetic lesions were associated with extracellular signal-regulated kinase 1/2 activation; however, only p53 heterozygous and compound mice showed increased levels of phosphorylated AKT and decreased p27 expression. The highest levels of cell proliferation were found in compound mice, but increased levels were also found with either increased ER(alpha) expression or p53 heterozygosity. Mice with increased ER(alpha) expression showed predicted higher levels of nuclear-localized ER(alpha), but this was attenuated in compound mice in association with a relative increase in Src phosphorylation. Parity protection was limited to p53 heterozygous mice and not found in mice with increased ER(alpha) alone. In summary, increased and deregulated ER(alpha) collaborates with p53 heterozygosity in increasing the risk of mammary preneoplasia development.

Frequent loss of heterozygosity at the interferon regulatory factor-1 gene locus in breast cancer

The interferon regulatory factor-1 (IRF1) gene, localized on chromosome 5q31.1, is mutated or rearranged in several cancers including some hematopoietic and gastric cancers. However, whether loss of IRF1 occurs in sporadic breast cancer is unknown. Loss of 5q12-31 is reported in 11% of sporadic breast cancers, and high-resolution array-CGH studies have shown loss at 5q31.1 in 50% of breast cancers with a mutated BRCA1 gene. Functionally, overexpression of IRF1 reduces, and a dominant negative IRF1 construct increases, tumorigenesis of human breast cancer xenografts. Taken together, these observations indicate that the IRF1 gene may play a potentially important role as a breast cancer tumor suppressor gene. In this study, we investigated allelic loss of the IRF1 gene in breast tumor specimens from 52 women with invasive breast cancer using an IRF1 intragenic dinucleotide polymorphic marker. Thirty-seven cases were informative. LOH at the IRF1 locus was detected in 32% of these informative cases (12/37). There was a significant association between IRF1 loss and both older age (P = 0.0167) and earlier stage (Stages 1 and 2) (P = 0.0165). To assess the association of IRF1 mRNA expression with clinical outcomes in breast cancer, we studied data from two published gene expression microarray datasets. In breast cancer patients, low IRF1 mRNA expression is strongly correlated with both risk of recurrence (OR = 3.00; P = 0.003; n = 273 cases) and risk of death (OR = 4.18; P = 0.004; n = 191 cases). Our findings strongly imply a tumor suppressor role for the IRF1 gene in breast cancer.

Gene therapy of benign gynecological diseases

Gene therapy is the introduction of genetic material into patient's cells to achieve therapeutic benefit. Advances in molecular biology techniques and better understanding of disease pathogenesis have validated the use of a variety of genes as potential molecular targets for gene therapy based approaches. Gene therapy strategies include: mutation compensation of dysregulated genes; replacement of defective tumor-suppressor genes; inactivation of oncogenes; introduction of suicide genes; immunogenic therapy and antiangiogenesis based approaches. Preclinical studies of gene therapy for various gynecological disorders have not only shown to be feasible, but also showed promising results in diseases such as uterine leiomyomas and endometriosis. In recent years, significant improvement in gene transfer technology has led to the development of targetable vectors, which have fewer side-effects without compromising their efficacy. This review provides an update on developing gene therapy approaches to treat common gynecological diseases such as uterine leiomyoma and endometriosis.

Mutation and accumulation of p53 related to results of adjuvant therapy of postmenopausal breast cancer patients

p53 protein accumulation and gene mutation have been implicated in resistance to cytotoxic treatment. This study was performed to further assess the predictive value of p53 in breast cancer. Postmenopausal patients were randomized to adjuvant chemotherapy with cyclophosphamide, metothrexate, or 5-fluorouracil (CMF) vs. postoperative radiotherapy. The patients were also randomized to adjuvant tamoxifen vs. no endocrine treatment. Immunohistochemistry (IHC) and single-strand conformation polymorphism (SSCP), followed by direct sequencing, was performed. The p53 altered group, regarded as positive for p53 gene mutation and/or p53 protein accumulation, tended to benefit more from CMF than from radiotherapy as compared with others regarding distant recurrences. In the group lacking p53 alteration there was a significantly decreased local recurrence rate in the radiotherapy group as compared with the CMF group (RR = 0.24, 95% CI = 0.083 0.62), whereas no benefit from radiotherapy was found for patients showing p53 alterations. Tamoxifen significantly decreased the rate of distant recurrence for estrogen receptor-positive patients with no apparent difference in relation to p53 alteration. It is suggested that p53 alteration indicates benefit from CMF compared with radiotherapy regarding distant recurrence-free survival and the best local control with radiotherapy is achieved in the absence of p53 alteration. Finally, altered p53 status is probably not a marker of resistance to tamoxifen.

p53 induces distinct epigenetic states at its direct target promoters

Background

The tumor suppressor protein p53 is a transcription factor that is mutated in many cancers. Regulation of gene expression by binding of wild-type p53 to its target sites is accompanied by changes in epigenetic marks like histone acetylation. We studied DNA binding and epigenetic changes induced by wild-type and mutant p53 in non-malignant hTERT-immortalized human mammary epithelial cells overexpressing either wild-type p53 or one of four p53 mutants (R175H, R249S, R273H and R280K) on a wild-type p53 background.

Results

Using chromatin immunoprecipitation coupled to a 13,000 human promoter microarray, we found that wild-type p53 bound 197 promoters on the microarray including known and novel p53 targets. Of these p53 targets only 20% showed a concomitant increase in histone acetylation, which was linked to increased gene expression, while 80% of targets showed no changes in histone acetylation. We did not observe any decreases in histone acetylation in genes directly bound by wild-type p53. DNA binding in samples expressing mutant p53 was reduced over 95% relative to wild-type p53 and very few changes in histone acetylation and no changes in DNA methylation were observed in mutant p53 expressing samples.

Conclusion

We conclude that wild-type p53 induces transcription of target genes by binding to DNA and differential induction of histone acetylation at target promoters. Several new wild-type p53 target genes, including DGKZ, FBXO22 and GDF9, were found. DNA binding of wild-type p53 is highly compromised if mutant p53 is present due to interaction of both p53 forms resulting in no direct effect on epigenetic marks.

Different mutant/wild-type p53 combinations cause a spectrum of increased invasive potential in nonmalignant immortalized human mammary epithelial cells

Aberrations of p53 occur in most, if not all, human cancers. In breast cancer, p53 mutation is the most common genetic defect related to a single gene. Immortalized human mammary epithelial cells resemble the earliest forms of aberrant breast tissue growth but do not express many malignancy-associated phenotypes. We created a model of human mammary epithelial tumorigenesis by infecting hTERT-HME1 immortalized human mammary epithelial cells expressing wild-type p53 with four different mutant p53 constructs to determine the role of p53 mutation on the evolution of tumor phenotypes. We demonstrate that different mutant/wild-type p53 heterozygous models generate loss of function, dominant negative activity, and a spectrum of gain of function activities that induce varying degrees of invasive potential. We suggest that this model can be used to elucidate changes that occur in early stages of human mammary epithelial tumorigenesis. These changes may constitute novel biomarkers or reveal novel treatment modalities that could inhibit progression from primary to metastatic breast disease.

Prognostic value of Bcl-2 in breast cancer patients treated with neoadjuvant anthracycline based chemotherapy

We have analyzed the predictive/prognostic value of Bcl-2 protein in breast cancer patients treated with neoadjuvant chemotherapy. One hundred and ten patients were submitted to two different chemotherapeutic regimens: a) 5-fluorouracil, adriamycin or epirubicin, and cyclophosphamide (FAC/FEC) during 2-6 cycles before surgery and 3 or 4 additional cycles of FAC/FEC after surgery (n=40) and b) doxorubicin (D) 75 mg/m(2) or epirubicin (E) 120 mg/m(2) during 4 cycles before surgery, and 6 cycles of cyclophosphamide, methotrexate, and 5-fluorouracil (CMF) after surgery (n=70). Bcl-2 expression, evaluated by immunohistochemistry, did not change significantly after chemotherapy and was not related to clinical/pathological response. In FAC/FEC group, Bcl-2 positive expression after chemotherapy correlated with better disease free survival (DFS) and overall survival (OS) (P=0.008 and P=0.001). In D/E group, Bcl-2 also correlated with better DFS and OS (P=0.03 and P=0.054) in the post-chemotherapy biopsies. An unusual nuclear localization of Bax was observed in some biopsies, but this localization did not correlate with the tumor response or outcome of the patients. We found that a high Bcl-2 expression had no predictive value but had prognostic value in breast cancer patients treated with neoadjuvant anthracycline based chemotherapy.

Immunologic markers of cancer progression and prognosis

During the past decade, significant progress has been made in understanding the interactions between the immune system and cancer. The re-emergence of cancer immunosurveillance and immunoediting concepts has provided an understanding of several immunologic markers that are associated with cancer progression and prognosis. Recent studies have attempted to define the critical role of tumor infiltration by lymphocytes as a reflection of a tumor-related immune response. More recently, there has been an improved ability to demonstrate distinct subsets of tumor-infiltrating lymphocytes (TILs) in different tumor compartments. Several of these studies indicate that the presence of TILs may be associated with improved clinical outcome in several human cancers. However, this improved clinical outcome is dependent upon the intratumoral balance and quality of TILs, or infiltration of regulatory T cells or myeloid-derived suppressor cells. Immunologic markers have an important role in demonstrating intermediate end points of a therapeutic intervention and ultimately may be useful in predicting clinical outcomes. These markers are important to the development of successful immunotherapy strategies in cancer.

Abrogation of p53 by its antisense in MCF-7 breast carcinoma cells increases cyclin D1 via activation of Akt and promotion of cell proliferation

The p53 protein has been a subject of intense research interest since its discovery as about 50% of human cancers carry p53 mutations. Mutations in the p53 gene are the most frequent genetic lesions in breast cancers suggesting a critical role of p53 in breast cancer development, growth and chemosensitivity. This report describes the derivation and characterization of MCF-7As53, an isogenic cell line derived from MCF-7 breast carcinoma cells in which p53 was abrogated by antisense p53 cDNA. Similar to MCF-7 and simultaneously selected hygromycin resistant MCF-7H cells, MCF-7As53 cells have consistent basal epithelial phenotype, morphology, and estrogen receptor expression levels at normal growth conditions. Present work documents investigation of molecular variations, growth kinetics, and cell cycle related studies in relation to absence of wild-type p53 protein and its transactivation potential as well. Even though wild-type tumor suppressor p53 is an activator of cell growth arrest and apoptosis-mediator genes such as p21, Bax, and GADD45 in MCF-7As53 cells, no alterations in expression levels of these genes were detected. The doubling time of these cells decreased due to depletion of G0/G1 cell phase because of constitutive activation of Akt and increase in cyclin D1 protein levels. This proliferative property was abrogated by wortmannin, an inhibitor of PI3-K/Akt signaling pathway. Therefore this p53 null cell line indicates that p53 is an indispensable component of cellular signaling system which is regulated by caveolin-1 expression, involving Akt activation and increase in cyclin D1, thereby promoting proliferation of breast cancer cells.

Phospholipid hydroperoxide glutathione peroxidase (PHGPx) expression is downregulated in poorly differentiated breast invasive ductal carcinoma

Phospholipid Hydroperoxide Glutathione Peroxidase (PHGPx) is the only known enzyme able to reduce lipid peroxides bound to cell membranes. Moreover it has been involved in apoptosis and can influence intracellular signaling. To investigate the possible relationship between PHGPx and human cancer we have quantified PHGPx expression levels by real-time quantitative PCR and immunohistochemistry in tissue samples of human breast invasive ductal carcinoma from 34 patients compared with their own controls of benign breast tissue. PHGPx expression levels were compared with the clinical and pathological data of these patients. The results showed that PHGPx expression levels are downregulated in poorly differentiated (grade 3) breast invasive ductal carcinoma (P = 0.0043). PHGPx expression levels decreased gradually with tumor grade from grade 1 to grade 3. We also found a downregulation of PHGPx in cases that showed p53 accumulation compared with cases without p53 immunostaining (P = 0.0011). PHGPx was also downregulated in cases without progesterone receptors (PR) immunostaining compared with cases with PR immunostaining (P = 0.0165). Grade 3, p53 immunostaining and absence of PR immunostaining are poor prognostic factors. These results suggest that PHGPx downregulation could be related with a poorer prognosis in breast invasive ductal carcinoma.

High-dose chemotherapy: how resistant is breast cancer?

This report reviews clinical experience with high-dose chemotherapy with stem-cell support in breast cancer and attempts to integrate clinical and molecular biological observations into a model of drug resistance. Despite the remarkable initial chemosensitivity of breast cancer, the majority of patients with advanced breast cancer die of their disease. In trials to date, high-dose chemotherapy has not been able to overcome primary drug resistance and patients with disease progression during induction therapy benefit little from further high-dose therapy. On the other hand, high-dose chemotherapy produces improved objective response rates compared with standard-dose chemotherapy due to converting some partial responses achieved by standard-dose induction therapy to complete response. This suggests that high-dose chemotherapy may overcome partial clinical drug resistance and may result in a more complete elimination of chemosensitive cells. Whether increased complete response rates will translate into higher cure rates and increased overall survival remains to be unequivocally demonstrated. There are multiple clinical patterns of drug failure including continued growth during chemotherapy, partial response followed by a period of stable disease, initial complete response with subsequent recurrence within a few months or after several years. Different mechanisms of drug resistance may operate at different stages of the disease and predispose patients to different clinical patterns of failure. A model of clonal progression of cancer is proposed that could explain several intriguing features of clinical drug resistance. We hypothesize that drug-sensitivity is an acquired characteristic of neoplastic cells and that a 'physiological drug-resistant' state may precede drug sensitivity at early stages of neoplastic transformation. Some recurrences may, in this context, represent progression of physiologically drug-resistant clones to sensitivity and subsequently to 'pathologic resistance' to chemotherapy. Optimal therapy to delay or prevent recurrence may differ depending on the stage and biology of the tumor and may include combinations of cytotoxic drugs and chemopreventive agents to arrest progression of early physiologically drug-resistant neoplastic stem cells.

p53 protein accumulation predicts resistance to endocrine therapy and decreased post-relapse survival in metastatic breast cancer

Introduction

Endocrine therapy is the most important treatment option for women with hormone receptor-positive breast cancer. The potential mechanisms for endocrine resistance involve estrogen receptor (ER)-coregulatory proteins and cross-talk between ER and other growth factor-signaling networks. However, the factors and pathways responsible for endocrine resistance are still poorly identified.

Materials and methods

The expression of HER2, p53, and Ki67 was examined by immunohistochemistry in primary breast tumour specimens from 73 metastatic breast cancer patients who received first-line treatment with endocrine therapy on relapse, and analysed to determine whether expression of these molecular markers affected the response to endocrine therapy.

Results

Of the 73 invasive ductal carcinomas, 12.3%, 21.9%, and 35.6% were positive for HER2 overexpression, p53 protein accumulation, and Ki67 expression, respectively. All patients received endocrine therapy as first-line treatment for metastatic breast cancer; 34 patients (46.6%) responded. Patients with primary breast tumours that had p53 protein accumulation and Ki67 expression showed significantly more resistance to endocrine therapy (P = 0.0049 and P = 0.024, respectively). There were also tendencies for HER2 overexpression to correlate with resistance to endocrine therapy, but this did not reach significance. p53 protein accumulation and HER2 overexpression significantly reduced post-relapse survival (P < 0.0001 and P = 0.001, respectively), and these factors were also statistically significant in a multivariate analysis.

Conclusion

These data suggest that p53 protein accumulation is helpful in selecting patients who may benefit from endocrine therapy and is a prognostic marker in hormone receptor-positive metastatic breast cancer.

Gene therapy and uterine leiomyoma: a review

Leiomyomas (fibroids) are common estrogen-dependent uterine tumours that cause significant morbidity for women and a substantial economic impact on health delivery systems. Currently, there is no effective medical treatment option for this condition-hysterectomy is the mainstay of management. This is not an attractive choice for many women, especially patients desiring to preserve their fertility potential. Gene therapy is becoming a clinical reality, with more than 600 clinical trials worldwide. Researchers have recently attempted to develop a gene-therapy-based approach for the ablation of uterine fibroids. The localized nature of this condition and its accessibility using different imaging or endoscopic techniques make it an attractive target for direct delivery of gene-based vectors. Recent work from our laboratory suggests the potential use of a dominant-negative form of estrogen receptor (ER) to inactivate estrogen signalling in leiomyoma cells and induce apoptosis. Our in vivo data in a mouse model demonstrate the ability of an adenovirus-expressing dominant-negative ER to arrest leiomyoma growth. We and others also have described the utility of the herpes simplex virus-thymidine kinase (HSV-TK) plus ganciclovir (GCV) suicide gene-therapy system to effectively eradicate leiomyoma cells by utilizing the bystandard effect phenomena and the high expression of gap-junction protein in these tumours. Further work on rat models will pave the way for future leiomyoma gene-therapy clinical trials and allow the realization of gene therapy as a viable non-surgical option for this common problem in women's health.

Inhibitory effects of costunolide on the telomerase activity in human breast carcinoma cells

Costunolide, a natural sesquiterpene compound, has been known having cytotoxic and chemopreventive effects on various human cancer cells. In the present study, we examined the effects of costunolide on telomerase activity and on the components of telomerase in MCF-7 (wild-type p53) and MDA-MB-231 (mutant p53) cells. We found that costunolide inhibited the growth and telomerase activity of MCF-7 and MDA-MB-231 cells in a concentration- and time-dependent manner. The expression of hTERT mRNA was also inhibited but hTR mRNA was not. In addition, the bindings of transcription factors in hTERT promoters were significantly decreased in both cells by the treatment of costunolide. These results suggest that costunolide inhibited the growth of both MCF-7 and MDA-MB-231 cells and this effect was mediated at least in part by a significant reduction in telomerase activity.

Increased copy number at 3p14 in breast cancer

INTRODUCTION

The present study was conducted to investigate if chromosome band 3p14 is of any pathogenic significance in the malignant process of breast cancer. Genetic studies have implicated a tumour suppressor gene on chromosome arm 3p and we have proposed LRIG1 at 3p14 as a candidate tumour suppressor. The LRIG1 gene encodes an integral membrane protein that counteracts signalling by receptor tyrosine kinases belonging to the ERBB family. LRIG1 mRNA and protein are expressed in many tissues, including breast tissue.

METHODS

In the present report we analysed the LRIG1 gene by fluorescence in situ hybridisation (FISH), LRIG1 mRNA by quantitative RT-PCR, and LRIG1 protein by western blot analysis. Two tumour series were analysed; one series consisted of 19 tumour samples collected between 1987 and 1995 and the other series consisted of 9 tumour samples with corresponding non-neoplastic breast tissues collected consecutively.

RESULTS

The LRIG1 gene showed increased copy number in 11 out of 28 tumours (39%) and only one tumour showed a deletion at this locus. Increased LRIG1 copy number was associated with increased levels of LRIG1 mRNA (two of three tumours) and protein (four of four tumours) in the tumours compared to matched non-neoplastic breast tissue, as assessed by RT-PCR and western blot analysis.

CONCLUSION

The molecular function of LRIG1 as a negative regulator of ERBB receptors questions the biological significance of increased LRIG1 copy number in breast cancer. We propose that a common, but hitherto unrecognised, breast cancer linked gene is located within an amplicon containing the LRIG1 locus at 3p14.3.

Interferon regulatory factor-1 (IRF-1) exhibits tumor suppressor activities in breast cancer associated with caspase activation and induction of apoptosis

We have directly assessed the ability of interferon regulatory factor-1 (IRF-1) to act as a tumor suppressor gene in human breast cancer cells and explored whether this suppressor function is mechanistically conferred by affecting cell cycle transition, apoptosis and/or caspase activation. We have used a dual approach, measuring whether overexpression of wild-type IRF-1 or a dominant negative IRF-1 (dnIRF-1) produce opposing effects on breast cancer cell proliferation in vitro or tumorigenicity in athymic nude mice. Mechanistic studies determined the effects of blocking endogenous IRF-1 expression on cell cycle transition by flow cytometry, on apoptosis by Annexin V staining, and on caspase activation by fluorescent substrate cleavage. IRF-1 mRNA (P < or = 0.001) and protein (P < or = 0.001) are highly expressed in non-tumorigenic, normal, mammary epithelial cells, with intermediate expression in tumorigenic, but non-metastatic, cells and very low expression in metastatic cell lines. In MCF-7 cells transfected with a wild-type IRF-1 (MCF-7/IRF-1), IRF-1 mRNA expression inversely correlates with the rate of cell proliferation (r = -0.91; P = 0.002). Conversely, expression of dnIRF-1 in both MCF-7 (MCF-7/dnIRF-1; p53 wild-type) and T47D cells (T47D/dnIRF-1; p53 mutant) increases cell proliferation (P < or = 0.001). In athymic nude mice, the incidence of MCF-7/IRF-1 xenografts is reduced (P = 0.045), whereas MCF-7/dnIRF-1 xenografts exhibit a significantly higher tumor incidence (P < or = 0.001). Effects of IRF-1/dnIRF-1 are mediated through changes in the rates of apoptosis and not through cell cycle regulation. MCF-7/dnIRF-1 cells exhibit a 50% decrease in basal apoptosis (P = 0.007) and a significant reduction in caspase 8 activity (P = 0.03); similar effects occur in T47D/dnIRF-1 cells, where the effects on apoptosis appear to be mediated through inhibition of caspases 3/7 (P < 0.001) and caspase 8 (P = 0.03). These data establish a functional role for IRF-1 in the growth suppression of breast cancer cells and strongly implicate IRF-1 as a tumor suppressor gene in breast cancer that acts, independent of p53, to control apoptosis.

interferon regulatory factor-1 mediates the proapoptotic but not cell cycle arrest effects of the steroidal antiestrogen ICI 182,780 (faslodex, fulvestrant)

Antiestrogens induce both cytostasis (cell cycle arrest) and apoptosis, but the relationship between these end points and the signaling that regulates their induction are unclear. We have previously implicated the transcription factor and putative tumor suppressor IFN regulatory factor-1 (IRF-1) in acquired antiestrogen resistance (Gu et al., Cancer Res, 62: 3428-3437, 2002). We now show the functional significance of IRF-1 in affecting antiestrogen responsiveness in estrogen receptor-positive antiestrogen-sensitive models (MCF-7, T47D, and ZR-75-1), a model of acquired antiestrogen resistance (MCF7/LCC9; estrogen receptor positive), and a model of de novo antiestrogen resistance (MDA-MB-231; estrogen receptor negative). Basal IRF-1 mRNA expression is lower in MCF7/LCC9 cells when compared with MCF-7, T47D, and ZR-75-1 cells. IRF-1 transcriptional activity in MCF-7/LCC9 cells is 18-fold lower than that seen in the parental cells (MCF-7/LCC1) and is comparable with that in MDA-MB-231 cells. Although IRF-1 mRNA expression is induced by ICI 182,780 in sensitive cells, this regulation is lost in MCF-7/LCC9 and is absent in MDA-MB-231 cells. Loss of IRF-1 regulation appears specific to antiestrogen resistance-resistant cells induce IRF-1 mRNA in response to the cytotoxic drug doxorubicin. A dominant-negative IRF-1 eliminates the ICI 182,780-induced apoptotic response (reduced >4-fold) and reduces MCF-7 and T47D cell sensitivity to the antiproliferative effects of ICI 182,780. This effect is not mediated by changes in cell cycle distribution; rather, dominant-negative IRF-1 reduces ICI 182,780-induced apoptosis. These data identify a novel mechanism of antiestrogen resistance and implicate IRF-1 as a key component in signaling some ER-mediated effects on apoptosis/cell survival.

Prognostic implication of p53 protein expression in relation to nuclear pleomorphism and the MIB-1 counts in breast cancer

BACKGROUND

A close correlation of the p53 protein expression to nuclear pleomorphism and proliferative activity in breast cancer has been reported. The prognostic implications of p53 protein expression, however, in relation to nuclear pleomorphism and proliferative activity in breast cancer remain controversial.

PATIENTS AND METHODS

Nuclear pleomorphism and immunohistochemical reactivity for p53 protein and MIB-1 were evaluated on formalin-fixed paraffin-stored sections from 250 patients with breast cancer for whom the median follow-up duration was 6.4 years.

RESULTS

p53 protein expression was positive in 66 (26.4%) of 250 cases. Nuclear pleomorphism was grade I or II in 169 (67.6%) cases and grade III in 81(32.4%)cases. The MIB-1 counts were more than 10% in 102 (40.8%) cases and less than 10% in 148 (59.2%) cases. There was a close correlation between p53 protein expression and nuclear pleomorphism (p<0.0001) and between p53 protein expression and MIB-1 counts (p<0.0001). Univariate analyses showed the 66 cases with positive p53 protein expression to have a significantly (p=0.0284) worse disease free survival (DFS) than the 184 cases with negative p53 protein expression. A multivariate analysis, however, on the variables including all of p53 protein expression, nuclear pleomorphism and MIB-1 counts indicated the MIB-1 counts (p=0.0041) as well as the lymph node status to be independently significant factors for DFS, while neither p53 protein expression nor nuclear pleomorphism were independently significant factors for DFS.

CONCLUSION

The present study demonstrated that the p53 protein expression, nuclear pleomorphism and MIB-1 counts all demonstrated prognostic significance for breast cancer, while the most significant prognostic indicator among these three biological parameters was the MIB-1 counts.

P53 and breast cancer

p53 mutation is the most common genetic abnormality found so far in human cancer, and in breast cancer p53 mutation/alteration is seen in up to 50% of primary carcinomas. Together with the increasing knowledge of the characteristics and understanding of the role of p53 over the last two decades, attention in recent years has been focused on how this knowledge can be used in clinical settings for patient care and management in terms of analyzing p53 as a potential marker for studying the relationship between p53 expression and tumour development, progression and outcome; and designing alternative treatment strategies specifically aimed at restoring normal p53 function.

Male versus female breast cancers. A population-based comparative immunohistochemical analysis

CONTEXT

The rate of male breast cancer is a small fraction of that observed in females, thus severely limiting our understanding of the pathogenesis of this condition. It remains unclear whether the biological behavior and tumor progression associated with male breast cancer parallel that of the female form.

OBJECTIVES

To evaluate the immunohistochemical profile of male breast carcinomas and to compare this profile with that of stage-matched female breast cancers.

DESIGN

Seventy-five cases of primary male breast cancer were identified using the records of the Saskatchewan Cancer Foundation over a period of 26 years (1970-1996). Fifty-nine of these cases had formalin-fixed, paraffin-embedded tissue blocks available for the purposes of this study. All cases were reviewed and a standardized modified Bloom-Richardson grading criterion was applied. Estrogen receptor status, progesterone receptor status, c-Erb-B2 expression, p53 expression, and Bcl-2 expression were evaluated by immunohistochemistry. Results from 240 consecutive cases of stage-matched female breast cancers analyzed in the same laboratory were used as a standard set for comparison.

RESULTS

Male breast cancers tended to be high grade (85% grade 3) in comparison with the female breast cancers (50% grade 3). In descriptive analysis across all stages of disease, male carcinomas were more frequently estrogen receptor positive (81% vs 69%) than their female counterparts. Despite their high grade, they were less likely to overexpress p53 (9% vs 28%) and Erb-B2 (5% vs 17%) than the female counterparts. There was no significant difference in either progesterone receptor (63% vs 56%) or Bcl-2 (79% vs 76%) overexpression. Stratified analysis by stage-matched controls showed no statistically significant differences among the men and women with stage I disease. However, in stage II-matched samples, statistically significant differences were observed between the 2 groups. The male cancers were more likely to overexpress estrogen receptor (81.6% vs 64.4%, P = .04), progesterone receptor (71.1% vs 47.5%, P = .01), and Bcl-2 (78.9% vs 69.4%, P = .20). They also showed statistically significant lower expression of p53 (7.9% vs 36.3%, P = .001) and Erb-B2 (5.3% vs 23.8% P = .01).

CONCLUSION

Male breast cancers display distinct immunophenotypic differences from those occurring in women, implying a different pathogenesis in the evolution and progression of this disease. Such differences may play key roles in therapeutic management, warranting different treatment strategies in comparison to female breast cancers.

Occult axillary lymph node metastases in breast cancer do matter: results of 10-year survival analysis

Axillary lymph node status is one of the most powerful prognostic factors for patients with breast cancer and is often critical in stratifying patients into adjuvant treatment regimens. In 203 apparently node-negative cases of breast cancer, a combination of immunohistochemical staining and step-sectioning identified occult metastases in 25% of cases. Ten-year follow-up information is available for these patients. Histologic features of the primary tumor and immunohistochemical staining for estrogen receptor, progesterone receptor, Her-2, and p53 were also evaluated. With multivariate analysis, both occult metastases and higher histologic grade of the primary tumor were independent predictors of disease-free survival. Histologic grade was the only significant independent predictor of overall survival. Estrogen receptor, progesterone receptor, Her-2, and p53 status did not predict the presence of metastases or survival when all tumor types were considered together. Metastases >0.5 mm significantly predicted a poorer disease-free survival when invasive ductal carcinomas were considered alone. Histologic grade was significantly associated with disease-free survival in the premenopausal and perimenopausal patients but not in the postmenopausal patients. The presence of occult metastases approached significance for overall survival in the premenopausal and perimenopausal patients but not in the postmenopausal patients.

Serial analysis of gene expression in normal p53 null mammary epithelium

Much evidence has accumulated implicating the p53 gene as of importance in breast carcinogenesis. However, much still remains to be uncovered on the specific downstream pathways influenced by this important activator/repressor of transcription. This study investigated the effects of a p53 null genotype on the transcriptome of 'normal' mouse mammary epithelium using a unique in vivo model of preneoplastic transformation. We used SAGE for the comparative analysis of p53 wild type (wt) and null mammary epithelium unexposed and exposed to hormonal stimulation. Analysis of the hormone exposed samples provided a comprehensive view of the dramatic changes in gene expression as consequence of the functional differentiation of the mammary epithelium in an in vivo system. We detected the dysregulation in p53(null) epithelium of <1% of the transcriptome. Changes in expression affected not only known p53 target genes, but also several unexpected genes such as Expi (Wdnm1), Cyp1b1, Gelsolin, Ramp2 and class I MHC genes. The dysregulation of specific genes and their potential use as preneoplastic markers was further validated using an independent model of premalignant mammary outgrowth lines. This is the first study to examine the transcriptome of very early stages of preneoplastic progression in an in vivo model that mimics human breast cancer.

Molecular and biologic markers of premalignant lesions of human breast

There is currently great interest in the detection and characterization of putative precursor breast cancer lesions because of the possibility of chemoprevention. Knowledge of the biologic features of premalignant lesions, although limited, is rapidly evolving. Premalignant breast lesions have been examined for the presence of genetic alterations and for the expression of biomarkers such as the estrogen receptor (ER), Ki67, p53, and HER2/neu. Data obtained from genetic studies of precursor breast lesions clearly support the contention that genetic alterations begin quite early in selected subsets of histologically benign lesions. Although the results of biomarker expression profiles have been contradictory, most studies agree that precursor lesions significantly overexpress ER and that progressive alterations in ER expression accompany the transition of normal cells to hyperplastic lesions and carcinoma in situ. So far, the collected evidence indicates that precursor lesions in the breast demonstrate biomarker expression profiles and genetic abnormalities that are distinct from those of terminal ductal lobular units but share some of these features with invasive tumors. Future research in this field is urgently needed to identify specific biomarkers of prognostic and predictive value, which can help not only in the selection of patients for chemopreventive therapy but in monitoring the progression of high-risk lesions.

The significance of immunohistochemistry in the diagnosis and therapy of neoplasms

This review article details the diagnostical significance of immunohistochemistry, which has developed during the last quarter of the century. Certainly, the advancement of monoclonal antibody technology has been of great significance in assuring the place of immunohistochemistry in the modern accurate microscopic diagnosis of human neoplasms, as a method of choice in histopathology. The fact still remains that in order to properly assess any immunohistochemical reactivity used for differential diagnostic purposes, the target cells have to be identified as neoplastically transformed cells by routine histopathological techniques. Selected groups of target molecules of great significance in cancer biology are discussed. The discovery of neoplasm-associated antigens has not only made the more accurate diagnosis of human cancer feasible but has also shed light on the extensive immunophenotypical heterogeneity of even the most closely linked human malignancies. The identification of disseminated neoplastically transformed cells by immunohistochemistry has allowed for a clearer picture of cancer invasion and metastasis, as well as the evolution of the tumour cell associated immunophenotype towards increased malignancy. Some possibilities of neoplasm-associated antigen targeted, receptor-directed immunotherapy are discussed and reviewed in this manuscript. Future antineoplastic therapeutical approaches should see the inclusion of a variety of immunotherapies, in the form of an individualised 'cocktail' specific for the particular immunophenotypical pattern associated with each individual patient's neoplastic disease.

Distinctive patterns of Her-2/neu, c-myc, and cyclin D1 gene amplification by fluorescence in situ hybridization in primary human breast cancers

BACKGROUND

Human solid tumors undergo clonal evolution as they progress, but evidence for specific sequences of genetic changes that occur in individual tumors and are recapitulated in other tumors is difficult to obtain.

METHODS

Patterns of amplification of Her-2/neu, c-myc, and cyclin D1 were determined by fluorescence in situ hybridization (FISH) in relation to the presence of p53 dysfunction and ploidy in 60 primary human breast cancers.

RESULTS

We show that there are clusters of genophenotypic abnormalities that distinguish lobular breast cancers from nonlobular tumors; that cyclin D1 amplification occurs prior to the divergence of lobular breast cancers from nonlobular cancers; that p53 dysfunction, Her-2/neu amplification, and c-myc amplification are characteristic features of nonlobular breast cancers, but not of lobular breast cancers; and that the frequencies of amplification of all three oncogenes examined increase progressively with increasing aneuploidy, but that each gene exhibits a different profile of increasing amplification in relation to tumor progression. Early amplification of c-myc appears to be an especially prominent feature of hypertetraploid/hypertetrasomic tumors.

CONCLUSIONS

The data suggest that in tumors containing multiple abnormalities, these abnormalities often accumulate in the same cells within each tumor. Furthermore, the same patterns of accumulation of multiple genophenotypic abnormalities are recapitulated in different tumors.

p53 missense mutations in microdissected high-grade ductal carcinoma in situ of the breast

BACKGROUND

To understand the role of sporadic mutations in the tumor suppressor gene p53 (also known as TP53) in the pathogenesis of breast cancer, it is important to identify at which histologic stage such mutations first occur. We previously showed that a p53 mutation present in invasive breast cancer was found in all surrounding areas of ductal carcinoma in situ (DCIS) but not in areas of hyperplasia or normal breast epithelium. In the present investigation, we studied patients with DCIS, but without invasive breast cancer, to determine the spectrum of DCIS types that can harbor a p53 mutation.

METHODS

Formalin-fixed, paraffin-embedded tissues from 94 patients with DCIS were evaluated histologically for the predominant cellular architectural pattern, degree of necrosis, and nuclear grade. Each specimen was also assigned an overall histologic grade (with the use of the Van Nuys Prognostic Index pathologic classification). Tissue specimens were stained immunohistochemically with an anti-p53 antibody. Positively stained tissue areas were analyzed for the presence of p53 mutations by single-strand conformation polymorphism and direct sequencing. All statistical tests were two-sided.

RESULTS

DCIS from 10 of 94 patients were found to contain p53 missense mutations. All 10 were of a solid or a comedo histologic pattern and contained cells of nuclear grade 2 or 3 (i.e., more abnormal nuclei). The frequency of p53 missense mutations was statistically significantly different among the three overall histologic grade categories (zero [0%] of 49 with low-grade DCIS, one [4.35%] of 23 with intermediate-grade DCIS, and nine [40.9%] of 22 with high-grade DCIS; df = 2 and P<.0001).

CONCLUSION

The DCIS types in patients in this series are representative of clinically detected DCIS. Our finding that p53 mutations can occur before the development of invasive breast cancer, particularly in DCIS of high histologic grade, has potentially important implications for prevention and treatment.

Quantitative p21(waf-1)/p53 immunohistochemical analysis defines groups of primary invasive breast carcinomas with different prognostic indicators

We used image cytometry to quantify the immunohistochemical expression of p21(waf-1) and p53 in primary breast carcinoma. Ratio analysis of the quantified p53/p21(waf-1) protein expression allowed us to define 3 groups of carcinomas, each characterized by specific pathological and biological profiles. The negative (NEG) group, characterized by negligible expression of both proteins, comprised small-sized, low-grade tumors associated with high contents of hormonal receptors and low growth fraction. In the NEG group, Ki-67 labelling index area (%LIa) was the only significant prognostic indicator. The P53H group, characterized by prevalence of p53 %LIa, was constituted by large-sized, high-grade tumors showing low hormonal receptor contents and high growth fraction. In the P53H group, both p53 and Ki-67 were inversely associated with both estrogen receptor (ER) and progesterone receptor (PGR), suggesting that extensive p53 immunostaining is related to poor differentiation and high proliferation. Only N status was prognostically significant in the P53H group. The P21H group, characterized by prevalence of p21(waf-1) %LIa, displayed intermediate pathological and biological features. A significant association between p53 and p21(waf-1) expression suggested functional stabilization of wtp53 and therefore possible DNA damage-dependent G1/S arrest (genetic instability) in the P21H group; P21(waf-1)expression was significantly associated with the presence of node metastasis. Patients in the P21H group had a higher recurrence rate and a shorter disease-free time interval from surgery with respect to the NEG group. Proportional hazard regression analysis disclosed Ki-67 %LIa and, to a lesser degree, PGR %LIa as significant relapse-free survival prognostic indicators.

Biophenotypes and survival of BRCA1 and TP53 deleted breast cancer in young women

The aim of this study was to examine the loss of heterozygosity (LOH) of BRCA1 (17q21) and TP53 (17p13.1) in early-onset breast cancer patients; to correlate biopathological characteristics with molecular alterations; and to investigate the survival of LOH-related cancers. BRCA1 and TP53 LOH were evaluated in 78 early-onset breast cancers (< or = 40 years, Group 1) and 80 patients with age > 55 years (Group 2). Cases were characterized for multiple biological markers (ER, PR, proliferation index (PI), NEU and p53). LOH was carried out on microdissected paraffin embedded tissues; microsatellites D17S855 (BRCA1) and D17S786 (TP53) were amplified by fluorescent PCR and analyzed by an automated DNA sequencer. Early-onset breast cancers showed a higher frequency of ductal histotype (89.7% vs. 56.3% p < 0.001), node-positive (53.8% vs. 38.7%), larger size (p = 0.017), higher mitotic rate (p = 0.025), higher nuclear and final grade (p = 0.01 and p = 0.001, respectively). D17S855 LOH was 32.8% in group 1 vs. 21% in group 2; D17S786 LOH was 50.7% vs. 31.3% (p = 0.03), respectively. BRCA1 LOH was correlated with higher PI (p = 0.032) and higher p53 expression (p < 0.001) in group 1 and with higher NEU expression (p = 0.028) in group 2. TP53 LOH was correlated with p53 overexpression (p = 0.03) in group 1. A worse clinical outcome in early-onset LOH related cancers emerged from follow-up data: TP53 and BRCA1 LOH were associated with a shorter relapse free interval (RFI) (p = 0.03) and a poorer overall survival (OS) (p = 0.04), respectively. This study underlines different biological profiles in the two age groups investigated, probably reflecting different mechanisms of carcinogenesis. In accordance with adverse histopathological features in early-onset patients, LOH-related cancers have an unfavorable prognosis.

Mutation analysis of p53 in ovarian tumors by DHPLC

Up to now, ovarian carcinomas represent a major health problem among female cancers because they are the leading cause of death from gynecological malignancy. A high proportion of these tumors selects for mutations in the p53 gene. There is evidence that inactivation of the p53 protein could indicate poor prognosis and chemoresistance of patients. To set up a fast and sensitive test for p53 defects in tumor tissues, we analyzed ovarian cancer cells by denaturing high-performance liquid chromatography (DHPLC). A primer set spanning the whole coding region of p53 with seven fragments was designed and appropriate heteroduplex detection in DHPLC analysis was elaborated. The analysis of 45 ovarian tumor specimens yielded 17 genetic alterations (38%) occurring exclusively in the malignant tissue of the patients. In addition, frequent polymorphisms present in normal compared to tumor tissue could serve as a tool for the rapid identification of loss of heterozygosity (LOH) in the tumor. We observed that LOH in intron 2 or 3 correlated well with a lack of one allele in mutated fragments. In conclusion, DHPLC screening appears to be a sensitive and effective test for genetic alterations in tumors with p53 involvement. Since p53 mutations point to a poor prognosis state in several cancers, a fast screening of tumor material for genetic variations may have implications for further individual treatment of patients.

P53 protein accumulation in non-invasive lesions surrounding p53 mutation positive invasive breast cancers

p53 mutation is a common event in sporadic breast cancer being found in 15-50% of invasive carcinomas. The purpose of this study was to determine the earliest histologic stage at which p53 mutation could be detected with a widely used anti-p53 antibody (DO7, Novocastra) which recognizes both wild type and mutant forms. p53 expression was assessed immunohistochemically in 12 primary breast carcinomas with known p53 mutations and in all pre-malignant epithelial lesions surrounding these invasive cancers. Strong p53 nuclear staining was found in all of the tumors known to have missense mutations and none of the tumors with truncation mutations. In cases with intense staining in the invasive carcinoma, a similar quality of staining was also seen in all areas of DCIS (ductal carcinoma in situ) and was representative of missense p53 mutations. Lighter nuclear staining intensity was observed in up to 40% of cells in areas of hyperplasia and in up to 30% of normal breast lobules irrespective of the type of mutation found in the invasive carcinoma. This weak staining was not specific to mutated p53 and may indicate increased amounts of normal p53 protein. We conclude that p53 inactivation occurs prior to invasion in breast carcinogenesis, with mutations being uniformly identified in DCIS associated with p53-mutated invasive carcinomas. In contrast, there is no evidence that epithelial hyperplasia or epithelial cells of the terminal duct lobular unit harbor the same mutations as their associated invasive carcinoma.