Somatic mutations in the BRCA1 gene in sporadic ovarian tumours.

The BRCA1 gene on chromosome 17q21 is responsible for an autosomal dominant syndrome of increased susceptibility to breast and ovarian cancer but no somatic mutations in tumours have yet been described. To study the potential role of BRCA1 in sporadic carcinogenesis, we analysed the genomic DNA of tumour and normal fractions of 47 ovarian cancers for mutations in BRCA1 using the single-strand conformation polymorphism technique. We now describe somatic mutations in the DNA of four tumours which also had loss of heterozygosity (LOH) at a BRCA1 intragenic marker. Our data support a tumour suppressor mechanism for BRCA1; somatic mutations and LOH may result in inactivation of BRCA1 in at least a small number of ovarian cancers.

BRCA2 germline mutations in male breast cancer cases and breast cancer families.

The breast cancer susceptibility gene, BRCA2 on chromosome 13q12-13, was recently isolated. Mutations in BRCA2 are thought to account for as much as 35% of all inherited breast cancer as wall as a proportion of inherited ovarian cancer. Many BRCA2-linked families also contain cases of male breast cancer. We have analysed germline DNA from 50 males with breast cancer (unselected for family history) and 26 individuals from site-specific female breast and breast-ovarian cancer families for mutations in BRCA2. All 17 breast-ovarian cancer families have been screened for BRCA1 coding region mutations and none were detected. Conformation-sensitive gel electrophoresis (CSGE) analysis of PCR-amplified DNA followed by direct sequencing was used to detect sequence variants. Three of eleven individuals carry the same mutation, all are of Ashkenazi Jewish descent, supporting the observation by Neuhausen et al. in this issue that there is a common mutation in this population. Eleven truncating mutations and nine polymorphisms were identified -- all were coding region variants. No loss-of-transcript mutations were identified in the sixteen samples for which this analysis was possible. Seven of the nine disease-associated mutations were detected in the 50 men with breast cancers; for thus in our series, BRCA2 mutations account for 14% of male breast cancer, all but one of which had a family history of male and/or female breast cancer.

The complete BRCA2 gene and mutations in chromosome 13q-linked kindreds.

Breast carcinoma is the most common malignancy among women in developed countries. Because family history remains the strongest single predictor of breast cancer risk, attention has focused on the role of highly penetrant, dominantly inherited genes in cancer-prone kindreds (1). BRCA1 was localized to chromosome 17 through analysis of a set of high-risk kindreds (2), and then identified four years later by a positional cloning strategy (3). BRCA2 was mapped to chromosomal 13q at about the same time (4). Just fifteen months later, Wooster et al. (5) reported a partial BRCA2 sequence and six mutations predicted to cause truncation of the BRCA2 protein. While these findings provide strong evidence that the identified gene corresponds to BRCA2, only two thirds of the coding sequence and 8 out of 27 exons were isolated and screened; consequently, several questions remained unanswered regarding the nature of BRCA2 and the frequency of mutations in 13q-linked families. We have now determined the complete coding sequence and exonic structure of BRCA2 (GenBank accession #U43746), and examined its pattern of expression. Here, we provide sequences for a set of PCR primers sufficient to screen the entire coding sequence of BRCA2 using genomic DNA. We also report a mutational analysis of BRCA2 in families selected on the basis of linkage analysis and/or the presence of one or more cases of male breast cancer. Together with the specific mutations described previously, our data provide preliminary insight into the BRCA2 mutation profile.

International expert panel on inflammatory breast cancer: consensus statement for standardized diagnosis and treatment.

BACKGROUND: Inflammatory breast cancer (IBC) represents the most aggressive presentation of breast cancer. Women diagnosed with IBC typically have a poorer prognosis compared with those diagnosed with non-IBC tumors. Recommendations and guidelines published to date on the diagnosis, management, and follow-up of women with breast cancer have focused primarily on non-IBC tumors. Establishing a minimum standard for clinical diagnosis and treatment of IBC is needed. METHODS: Recognizing IBC to be a distinct entity, a group of international experts met in December 2008 at the First International Conference on Inflammatory Breast Cancer to develop guidelines for the management of IBC. RESULTS: The panel of leading IBC experts formed a consensus on the minimum requirements to accurately diagnose IBC, supported by pathological confirmation. In addition, the panel emphasized a multimodality approach of systemic chemotherapy, surgery, and radiation therapy. CONCLUSIONS: The goal of these guidelines, based on an expert consensus after careful review of published data, is to help the clinical diagnosis of this rare disease and to standardize management of IBC among treating physicians in both the academic and community settings.

Urban-rural differences of gynaecological malignancies in Egypt (1999-2002).

OBJECTIVE: In previous studies, we have shown a three to four times higher urban incidence of breast cancer and estrogen receptor-positive breast cancers in the Gharbiah Province of Egypt. We investigated the urban-rural incidence differences of gynaecologic malignancies (uterine, ovarian and cervical cancers) to explore if they show the same trend that we found for breast cancer. DESIGN: Cancer registry-based incidence comparison. SETTING: Gharbiah population-based cancer registry (GPCR), Tanta, Egypt. SAMPLE: All patients with uterine, ovarian and cervical cancer in GPCR from 1999 to 2002. METHODS: We calculated uterine, ovarian and cervical cancer incidence from 1999 to 2002. For each of the three cancers, we calculated the overall and age-specific rates for the province as a whole, and by urban-rural status, as well as for the eight districts of the province. RESULTS: Incidence of all three cancer sites was higher in urban than in rural areas. Uterine cancer showed the highest urban-rural incidence rate ratio (IRR = 6.07, 95% CI = 4.17, 8.85). Uterine cancer also showed the highest urban incidence in the oldest age group (70+ age category, IRR = 14.39, 95% CI = 4.24, 48.87) and in developed districts (Tanta, IRR = 4.14, 95% CI = 0.41, 42.04). Incidence rates by groups of cancer sites showed an increasing gradient of urban incidence for cancers related to hormonal aetiology, mainly of the breast and uterus (IRR = 4.96, 95% CI = 2.86, 8.61). CONCLUSIONS: The higher urban incidence of uterine cancer, coupled with our previous findings of higher incidence of breast cancer and estrogen receptor positive breast cancer in urban areas in this region, may be suggestive of possible higher exposure to environmental estrogenic compounds, such as xenoestrogens, in urban areas.

RhoC GTPase, a novel transforming oncogene for human mammary epithelial cells that partially recapitulates the inflammatory breast cancer phenotype.

Inflammatory breast cancer (IBC) is the most aggressive form of breast cancer and is phenotypically distinct from other forms of locally advanced breast cancer. In a previous study, we identified specific genetic alterations of IBC that could account for a highly invasive phenotype. RhoC GTPase was overexpressed in 90% of IBC archival tumor samples, but not in stage-matched, non-IBC tumors. To study the role of RhoC GTPase in contributing to an IBC-like phenotype, we generated stable transfectants of human mammary epithelial cells overexpressing the RhoC gene. The HME-RhoC transfectants formed large colonies under anchorage-independent growth conditions, were more motile, and were invasive. In conjunction with an increase in motility, overexpression of RhoC led to an increase in actin stress fiber and focal adhesion contact formation. Furthermore, orthotopic injection into immunocompromised mice led to tumor formation. Taken together, these data indicate that RhoC GTPase is a transforming oncogene in human mammary epithelial cells and can lead to a highly invasive phenotype, akin to that seen in IBC.

Distinct regions of allelic loss on 13q in prostate cancer.

Loss of heterozygosity (LOH) involving the long arm of chromosome 13 has been reported to occur in as many as one third of primary prostate cancers. Candidate tumor suppressor genes on 13q that may be important in the development of prostate cancer include the retinoblastoma susceptibility gene (RBI) and a gene associated with inherited breast cancer (BRCA2). To define the pattern of allelic loss of 13q in prostate cancer, LOH analysis was performed using nine mapped polymorphic markers spanning the entire chromosomal arm. Nineteen (48%) of 40 prostate cancer cases obtained following radical prostatectomy demonstrated atllelic loss with at least one marker. Furthermore, 13 (33%) of 40 cases had evidence of allelic loss involving a region of 13q14 containing RB1. To test the hypothesis that RB1 is the targeted tumor suppressor gene in this region, 37 of 40 cases were assessed for expression of pRB, the protein product of RB1 using immunohistochemical techniques. By this analysis, 8 (22%) of 37 prostate tumors demonstrated no pRB expression. However, allelic loss at RB1, assessed with an intragenic marker, did not correlate with absent pRB expression (Fisher's exact test, P=0.375). Taken together, these data confirm that allelic loss of a common region of 13q14 occurs in approximately one third of prostate cancers. Lack of correlation of LOH at RB1 with absent pRB expression suggests the existence of another tumor suppressor gene in this region important in prostate cancer.

Breast conservation and prolonged chemotherapy for locally advanced breast cancer: the University of Michigan experience.

PURPOSE: To determine whether breast conservation and prolonged neoadjuvant chemotherapy have efficacy in locally advanced breast cancer (LABC), as measured by survival and rate of breast conservation. MATERIALS AND METHODS: Eighty-nine patients with stage III disease were enrolled at the University of Michigan (UM) onto a prospective nonrandomized trial. Patients received nine 21-day cycles of neoadjuvant chemohormonal therapy that consisted of doxorubicin 30 mg/m2 and cyclophosphamide 750 mg/m2 intravenously on day 1, conjugated estrogens 0.625 mg orally twice daily on days 6 to 8, methotrexate 40 mg/m2 and fluorouracil 500 mg/m2 intravenously on day 8, and tamoxifen 10 mg orally twice daily on days 9 to 14. Patients with a negative biopsy received radiation only, while those with residual disease underwent mastectomy and postoperative radiotherapy. Eight more cycles of chemohormonal therapy were administered after local-regional therapy. RESULTS: The clinical response rate to neoadjuvant therapy was 97%, 28% of patients had a complete pathologic response evaluated at biopsy. Five-year overall and disease-free survival probabilities were 54% and 44%, respectively. The median disease-free survival time was 2.4 years. The 5-year actuarial rates of local-regional control with local failure as only first failure were 82% and 78% following radiotherapy, and mastectomy and radiotherapy, respectively (P = .99). CONCLUSION: Prolonged neoadjuvant chemohormonal therapy and biopsy-driven local therapy have efficacy in LABC, with 28% of patients being candidates for breast conservation and a 5-year overall survival rate of 54%.

Tamoxifen and chemotherapy for axillary node-negative, estrogen receptor-negative breast cancer: findings from National Surgical Adjuvant Breast and Bowel Project B-23.

PURPOSE: Uncertainty about the relative worth of doxorubicin/cyclophosphamide (AC) and cyclophosphamide/methotrexate/fluorouracil (CMF), as well as doubt about the propriety of giving tamoxifen (TAM) with chemotherapy to patients with estrogen receptor-negative tumors and negative axillary nodes, prompted the National Surgical Adjuvant Breast and Bowel Project to initiate the B-23 study. PATIENTS AND METHODS: Patients (n = 2,008) were randomly assigned to CMF plus placebo, CMF plus TAM, AC plus placebo, or AC plus TAM. Six cycles of CMF were given for 6 months; four cycles of AC were administered for 63 days. TAM was given daily for 5 years. Relapse-free survival (RFS), event-free survival (EFS), and survival (S) were determined by using life-table estimates. Tests for heterogeneity of outcome used log-rank statistics and Cox proportional hazards models to detect differences across all groups and according to chemotherapy and hormonal therapy status. RESULTS: No significant difference in RFS, EFS, or S was observed among the four groups through 5 years (P =.96,.8, and.8, respectively), for those aged < or = 49 years (P =.97,.5, and.9, respectively), or for those aged > or = 50 years (P =.7,.6, and.6, respectively). A comparison between all CMF- and all AC-treated patients demonstrated no significant differences in RFS (87% at 5 years in both groups, P =.9), EFS (83% and 82%, P =.6), or S (89% and 90%, P =.4). There were no significant differences in RFS, EFS, or S between CMF and AC in patients aged < or = 49 or > or = 50 years. No significant difference in any outcome was observed when chemotherapy-treated patients who received placebo were compared with those given TAM. RFS in both groups was 87% (P =.6), 87% in patients aged < or = 49 (P =.9), and 88% and 87%, respectively (P =.4), in those aged > or = 50 years. CONCLUSION: There was no significant difference in the outcome of patients who received AC or CMF. TAM with either regimen resulted in no significant advantage over that achieved from chemotherapy alone.

A novel putative low-affinity insulin-like growth factor-binding protein, LIBC (lost in inflammatory breast cancer), and RhoC GTPase correlate with the inflammatory breast cancer phenotype.

Inflammatory breast cancer is a rapidly growing, distinct form of locally advanced breast cancer that carries a guarded prognosis. To identify the genes that contribute to this aggressive phenotype, we compared under- and overexpressed sequences in an inflammatory breast tumor cell line with those of actively replicating normal human mammary epithelial cell lines using differential display. Of the 17 transcripts isolated and characterized from these experiments, overexpression of RhoC GTPase and loss of expression of a novel gene on 6q22, LIBC (lost in inflammatory breast cancer), were highly correlated (P<0.0095 and P<0.0013, respectively) with the inflammatory phenotype when a panel of archival inflammatory breast cancers was compared with noninflammatory stage III breast cancers by in situ hybridization. This study suggests two new molecular markers specific for inflammatory breast cancer.

Treatment of metastatic cancer with tetrathiomolybdate, an anticopper, antiangiogenic agent: Phase I study.

Preclinical and in vitro studies have determined that copper is an important cofactor for angiogenesis. Tetrathiomolybdate (TM) was developed as an effective anticopper therapy for the initial treatment of Wilson's disease, an autosomal recessive disorder that leads to abnormal copper accumulation. Given the potency and uniqueness of the anticopper action of TM and its lack of toxicity, we hypothesized that TM would be a suitable agent to achieve and maintain mild copper deficiency to impair neovascularization in metastatic solid tumors. Following preclinical work that showed efficacy for this anticopper approach in mouse tumor models, we carried out a Phase I clinical trial in 18 patients with metastatic cancer who were enrolled at three dose levels of oral TM (90, 105, and 120 mg/day) administered in six divided doses with and in-between meals. Serum ceruloplasmin (Cp) was used as a surrogate marker for total body copper. Because anemia is the first clinical sign of copper deficiency, the goal of the study was to reduce Cp to 20% of baseline value without reducing hematocrit below 80% of baseline. Cp is a reliable and sensitive measure of copper status, and TM was nontoxic when Cp was reduced to 15-20% of baseline. The level III dose of TM (120 mg/ day) was effective in reaching the target Cp without added toxicity. TM-induced mild copper deficiency achieved stable disease in five of six patients who were copper deficient at the target range for at least 90 days.

Germline BRCA1 mutations and loss of the wild-type allele in tumors from families with early onset breast and ovarian cancer.

The BRCA1 gene on human chromosome 17q21 is responsible for an autosomal dominant syndrome of inherited early onset breast/ovarian cancer. It is estimated that women harboring a germline BRCA1 mutation incur an 85% lifetime risk of breast cancer and a greatly elevated risk of ovarian cancer. The BRCA1 gene has recently been isolated and mutations have been found in the germline of affected individuals in linked families. Previous studies of loss of heterozygosity (LOH) in breast tumors have been carried out on sporadic tumors derived from individuals without known linkage to BRCA1 and on tumors from linked families. Loss of large regions of chromosome 17 has been observed, but these LOH events could not be unequivocally ascribed to BRCA1. We have studied 28 breast and 6 ovarian tumors from families with strong evidence for linkage between breast cancer and genetic markers flanking BRCA1. These tumors were examined for LOH using genetic markers flanking and within BRCA1, including THRA1, D17S856, EDH17B1, EDH17B2, and D17S183. Forty-six percent (16/34) of tumors exhibit LOH which includes BRCA1. In 8 of 16 tumors the parental origin of the deleted allele could be determined by evaluation of haplotypes of associated family members; in 100% of these cases, the wild-type allele was lost. In some of these families germline mutations in BRCA1 have been determined; analyses of tumors with LOH at BRCA1 have revealed that only the disease-related allele of BRCA1 was present. These data strongly support the hypothesis that BRCA1 is a tumor suppressor gene.

RhoC GTPase overexpression modulates induction of angiogenic factors in breast cells.

Inflammatory breast cancer (IBC) is a distinct and aggressive form of locally advanced breast cancer. IBC is highly angiogenic, invasive, and metastatic at its inception. Previously, we identified specific genetic alterations of IBC that contribute to this highly invasive phenotype. RhoC GTPase was overexpressed in 90% of archival IBC tumor samples, but not in stage-matched, non-IBC tumors. To study the role of RhoC GTPase in contributing to an IBC-like phenotype, we generated stable transfectants of human mammary epithelial cells overexpressing the RhoC gene, and studied the effect of RhoC GTPase overexpression on the modulation of angiogenesis in IBC. Levels of vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), interleukin-6 (IL-6), and interleukin-8 (IL-8) were significantly higher in the conditioned media of the HME-RhoC transfectants than in the untransfected HME and HME-beta-galactosidase control media, similar to the SUM149 IBC cell line. Inhibition of RhoC function by introduction of C3 exotransferase decreased production of angiogenic factors by the HME-RhoC transfectants and the SUM149 IBC cell line, but did not affect the control cells. These data support the conclusion that overexpression of RhoC GTPase is specifically and directly implicated in the control of the production of angiogenic factors by IBC cells.

Copper deficiency as an anti-cancer strategy.

Copper is a tightly regulated trace element. Disruptions of copper homeostasis are rare and they cause serious disorders such as Wilson's disease and Menkes disease. Copper also plays an important role in promoting physiological and malignant angiogenesis. Formation of new blood vessels by a tumor enables tumor growth, invasion and metastasis. The copper chelator tetrathiomolybdate (TM), which quickly and effectively depletes copper stores, is under investigation as an anti-angiogenic agent. Promising results in vitro, in pre-clinical animal models and in an early (phase I) clinical trial have led to ongoing phase II evaluation of TM in patients with advanced cancers.

Genetic analysis of eight breast-ovarian cancer families with suspected BRCA1 mutations.

BRCA1 is a breast cancer-related tumor suppressor gene located on human chromosome 17q21. Inherited mutations in BRCA1 are thought to be responsible for approximately half of all inherited breast cancer and to confer increased risk for ovarian, colon, or prostate cancer. Studies of affected families and population-based studies have provided some information on the prevalence of BRCA1 mutations in Caucasian U.S. and European populations as well as on the penetrance of these mutations. We review the available data on the epidemiology of breast cancer with specific reference to BRCA1. In addition, we describe the genetic analysis of one large family with multiple affected individuals now known to harbor a BRCA1 germline mutation but initially identified by genetic linkage analysis. This family is presented as a model of the challenges that can be encountered in genetic analysis of familial forms of cancer. To this end, we compare the outcome of analysis before and after the identification of a mutation that predisposes family members to early-onset breast and ovarian cancers. We describe seven additional families with evidence of linkage between breast cancer and genetic markers in the BRCA1 region. Each of these families generated a 2-point LOD (i.e., logarithm of the odds) score greater than 1.18 for at least one polymorphic marker flanking BRCA1. These families have formed the basis of our efforts to characterize BRCA1 mutations. First-pass mutation analysis using the single-strand conformation polymorphism approach failed to identify any mutations in the seven families. We consider the possible reasons for the apparent low mutation-detection efficiency.

The use of mammography in breast preservation in locally advanced breast cancer.

PURPOSE: As the feasibility of breast preservation in locally advanced breast cancer is currently under evaluation, little information is available correlating mammographic changes to chemotherapy with local outcome. To evaluate the role of mammography in selecting candidates with locally advanced breast cancer for conservative local therapy, we analyzed mammographic changes in the breast to induction chemotherapy and correlated the radiologic appearance with pathologic outcome. METHODS AND MATERIALS: From 1985 through 1993, 91 patients with Stage III breast cancer were enrolled on a multimodality clinical trial using chemohormonal therapy followed by local treatment and maintenance therapy. Induction therapy consisted of cyclophosphamide, doxorubicin, methotrexate,and 5-fluorouracil with hormonal synchronization using tamoxifen and conjugated estrogens. After nine cycles, surgical biopsies of the breast were performed. Through 1988, clinical examination alone directed the site for postinduction biopsy; for patients treated after 1988, mammography, in addition to physical examination, determined the biopsy location. Local treatment was determined by biopsy result. Patients with a pathologic complete response received radiation only to the breast adn regional nodes, while those with pathologically proven residual disease underwent mastectomy and postoperative radiotherapy. Nine additional cycles of maintenance chemotherapy were administered. RESULTS: Fifty-five of 91 patients (58%) obtained a clinical complete response (CR) to induction chemotherapy. Twenty-eight of the 53 women with a clinical CR had both pre- and postinduction mammograms. Of these 28 women, 9 obtained a pathologic CR and 19 obtained a pathologic partial response (PR). Fifty-five percent of the pathologic complete responders had resolution of mammographic abnormalities on the postinduction mammograms. Sixty-eight percent (13) of the pathologic partial responders had abnormal mammographic findings. The positive predictive value for residual cancer using physical examination was 92%, while the negative predictive value was only 36%. Among patients with a clinical complete response, the positive and negative predictive values for residual cancer using postinduction mammography were 79% and 56%, respectively. Limitations of mammography included uncertain significance of residual microcalcifications and residual masses on postinduction chemotherapy mammograms. CONCLUSIONS: Although mammography improved the accuracy of noninvasive evaluations in patients with a clinical complete response, pathologic assessment was still required to determine appropriate local therapy. More sensitive imaging modalities or modifications of film-screen mammography may improve noninvasive detection of residual disease following induction chemotherapy.

Assessment of genetic testing and related counseling services: current research and future directions.

With the recent completion of the sequencing of the Human Genome, genetic testing will increasingly become available for a greater number of medical conditions, many of which are those that manifest in adulthood (e.g., various cancers, cardiovascular disease, diabetes) or for which little or no treatments are available (e.g., Alzheimer disease). Genetic services, defined here as those relating to genetic testing and counseling, will be with helping more individuals deal with medical information that affects their health directly, as opposed to affecting primarily the health of their offspring. This paper reviews the existing research in the genetic testing and counseling literature and presents an evaluation framework outlining the intended outcomes of genetic services. The purpose of this framework is to provide an overview of the potential outcomes of these services and highlight constructs for future research in this area. In addition, other issues that will affect the assessment of genetic services are raised, using examples from the existing literature. Ultimately, the goal of this paper is to highlight and suggest directions researchers can take to produce the information needed to guide genetic testing and counseling practice. Moreover, as genetic knowledge is increasingly applied towards the prevention and treatment of various common, chronic disease conditions, genetic information will have implications for providers outside of the traditional medical genetics realm, such as primary care providers and public health practitioners. A better understanding of the outcomes of genetic testing and counseling will provide a basis from which to ensure an appropriate application of genetic information by all those who eventually provide care and "genetic" services.

Risk assessment and presymptomatic molecular diagnosis in hereditary breast cancer.

Breast cancer susceptibility genes are being isolated at a rapid pace. Current molecular diagnostic techniques are being adapted to detect mutations in the germline and in tumors. The isolation of the breast and ovarian cancer gene 1 (BRCA1) has brought about the potential for screening large numbers of individuals for genetically increased susceptibility to breast cancer. The advantages and limitations of presymptomatic testing are discussed.

The role of copper suppression as an antiangiogenic strategy in head and neck squamous cell carcinoma.

OBJECTIVE: To determine whether tetrathiomolybdate (TM), a powerful chelator of copper, is capable of lowering the body stores of copper and suppressing the growth of head and neck squamous cell carcinoma in an orthotopic murine model. STUDY DESIGN: In vivo, murine model. METHODS: Twelve 8-week-old male C3H/HeJ mice were assigned to either a TM treatment group (n = 7) or a control group (n = 5). Serum samples were obtained from a single mouse in each group to measure the level of ceruloplasmin as a surrogate marker of total body copper on days 0, 4, and 7. Mice in both groups received a floor-of-mouth injection of 1.5 x 105 SCC VII/SF cells. After 7 to 10 days of tumor growth the treatment group received fresh water daily, to which TM was added to achieve an oral intake of 50 mg per mouse. The control group received only fresh drinking water daily. Tumor volume measurements were obtained every other day. Microvessel density counts were assessed in the tumors by Factor VIII analysis. RESULTS: Measurable tumor growth was achieved in 100% of the mice by the tenth day. Total body copper was reduced by 28% from baseline levels in mice in the treatment group. The difference in mean tumor volume in the control group was 4.7 times greater than the TM-treated group at the completion of treatment (3004 mm3 and 633mm3, respectively). This accounted for an overall suppression rate of 79% (P =.008; two-tailed Student t test). In addition, microvessel density was reduced by 50% in the TM-treated group. CONCLUSION: In this initial study, the first of its kind in head and neck squamous cell carcinoma, we have demonstrated the ability of TM to significantly suppress both the growth of squamous cell carcinoma and tumor vascularity in this orthotopic murine model, suggesting its potential for efficacy in the treatment of this disease in humans.

Downregulation of EZH2 decreases growth of estrogen receptor-negative invasive breast carcinoma and requires BRCA1.

Increased levels of enhancer of zeste homolog 2 (EZH2), a critical regulator of cellular memory, are associated with negative estrogen receptor (ER) expression and disease progression in breast cancer. High levels of EZH2 signal the presence of metastasis and poor outcome in breast cancer patients. To test the hypothesis that deregulation of EZH2 contributes to ER-negative breast cancer progression, EZH2 expression was inhibited in ER-negative breast cancer cells MDA-MB-231 and CAL51 using a lentivirus system. EZH2 knockdown decreased proliferation and delayed the G(2)/M cell-cycle transition, although not affecting apoptosis. In vivo, EZH2 downregulation significantly decreased breast xenograft growth and improved survival. EZH2 knockdown upregulated BRCA1 protein. Of note, BRCA1 knockdown was sufficient to rescue the effects of EZH2 downregulation on proliferation, G(2)/M arrest, and on the levels of hyperphosphorylated mitotic Cdc25C and Cyclin B1 proteins, crucial for entry into mitosis. Invasive ER-negative breast carcinomas show significant overexpression of EZH2 and downregulation of BRCA1 proteins. Taken together, we show that EZH2 is important in ER-negative breast cancer growth in vivo and in vitro, and that BRCA1 is required for the proliferative effects of EZH2. Blockade of EZH2 may provide a prime target to prevent and/or halt ER-negative breast cancer progression.