Pre-surgical trial of the AKT inhibitor MK-2206 in patients with operable invasive breast cancer: a New York Cancer Consortium trial

Introduction: The PI3K/AKT/mTOR pathway is an oncogenic driver in breast cancer (BC). In this multi-center, pre-surgical study, we evaluated the tissue effects of the AKT inhibitor MK-2206 in women with stage I-III BC. Materials and methods: Two doses of weekly oral MK2206 were administered at days − 9 and − 2 before surgery. The primary endpoint was reduction of pAktSer473 in breast tumor tissue from diagnostic biopsy to surgery. Secondary endpoints included changes in PI3K/AKT pathway tumor markers, tumor proliferation (ki-67), insulin growth factor pathway blood markers, pharmacokinetics (PK), genomics, and MK-2206 tolerability. Paired t tests were used to compare biomarker changes in pre- and post-MK-2206, and two-sample t tests to compare with prospectively accrued untreated controls. Results: Despite dose reductions, the trial was discontinued after 12 patients due to grade III rash, mucositis, and pruritus. While there was a trend to reduction in pAKT after MK-2206 (p = 0.06), there was no significant change compared to controls (n = 5, p = 0.65). After MK-2206, no significant changes in ki-67, pS6, PTEN, or stathmin were observed. There was no significant association between dose level and PK (p = 0.11). Compared to controls, MK-2206 significantly increased serum glucose (p = 0.02), insulin (p < 0.01), C-peptide (p < 0.01), and a trend in IGFBP-3 (p = 0.06). Conclusion: While a trend to pAKT reduction after MK-2206 was observed, there was no significant change compared to controls. However, the accrued population was limited, due to toxicity being greater than expected. Pre-surgical trials can identify in vivo activity in the early drug development, but side effects must be considered in this healthy population

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Pre-surgical trial of the AKT inhibitor MK-2206 in patients with operable invasive breast cancer: a New York Cancer Consortium trial.

INTRODUCTION: The PI3K/AKT/mTOR pathway is an oncogenic driver in breast cancer (BC). In this multi-center, pre-surgical study, we evaluated the tissue effects of the AKT inhibitor MK-2206 in women with stage I-III BC. MATERIALS AND METHODS: Two doses of weekly oral MK2206 were administered at days - 9 and - 2 before surgery. The primary endpoint was reduction of pAktSer473 in breast tumor tissue from diagnostic biopsy to surgery. Secondary endpoints included changes in PI3K/AKT pathway tumor markers, tumor proliferation (ki-67), insulin growth factor pathway blood markers, pharmacokinetics (PK), genomics, and MK-2206 tolerability. Paired t tests were used to compare biomarker changes in pre- and post-MK-2206, and two-sample t tests to compare with prospectively accrued untreated controls. RESULTS: Despite dose reductions, the trial was discontinued after 12 patients due to grade III rash, mucositis, and pruritus. While there was a trend to reduction in pAKT after MK-2206 (p = 0.06), there was no significant change compared to controls (n = 5, p = 0.65). After MK-2206, no significant changes in ki-67, pS6, PTEN, or stathmin were observed. There was no significant association between dose level and PK (p = 0.11). Compared to controls, MK-2206 significantly increased serum glucose (p = 0.02), insulin (p < 0.01), C-peptide (p < 0.01), and a trend in IGFBP-3 (p = 0.06). CONCLUSION: While a trend to pAKT reduction after MK-2206 was observed, there was no significant change compared to controls. However, the accrued population was limited, due to toxicity being greater than expected. Pre-surgical trials can identify in vivo activity in the early drug development, but side effects must be considered in this healthy population.

Proteomic modulation in breast tumors after metformin exposure: results from a 'window of opportunity' trial

Purpose. Reverse Phase Protein Array (RPPA) is a high-throughput antibody-based technique to assess cellular protein activity. The goal of this study was to assess protein marker changes by RPPA in tumor tissue from a pre-surgical metformin trial in women with operable breast cancer (BC). Methods. In an open-label trial, metformin 1500-mg PO daily was administered prior to resection in 35 non-diabetic patients with stage 0-III BC, body mass index ≥25 kg/m2. For RPPA, formalin-fixed paraffin-embedded (FFPE) samples were probed with 160 antibodies. Paired and two-sample t-tests were performed (p ≤ 0.05). Multiple comparisons were adjusted for by fixing the false discovery rate at 25 %. We evaluated whether pre- and post-metformin changes of select markers by RPPA were identified by immunohistochemistry (IHC) in these samples. We also assessed for these changes by western blot in metformin-treated BC cell lines. Results. After adjusting for multiple comparisons in the 32 tumors from metformin-treated patients vs. 34 untreated historical controls, 11 proteins were significantly different between cases vs. controls: increases in Raptor, C-Raf, Cyclin B1, Cyclin D1, TRFC, and Syk; and reductions in pMAPKpT202,Y204, JNKpT183,pT185, BadpS112, PKC.alphapS657, and SrcpY416. Cyclin D1 change after metformin by IHC was not observed. In cell lines, reductions in JNKpT183 and BadpS112 were seen, with no change in Cyclin D1 or Raptor. Conclusions. These results suggest that metformin modulates apoptosis/cell cycle, cell signaling, and invasion/motility. These findings should be assessed in larger metformin trials. If confirmed, associations between these changes and BC clinical outcome should be evaluated (AU)

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Proteomic modulation in breast tumors after metformin exposure: results from a "window of opportunity" trial.

PURPOSE: Reverse Phase Protein Array (RPPA) is a high-throughput antibody-based technique to assess cellular protein activity. The goal of this study was to assess protein marker changes by RPPA in tumor tissue from a pre-surgical metformin trial in women with operable breast cancer (BC). METHODS: In an open-label trial, metformin 1500-mg PO daily was administered prior to resection in 35 non-diabetic patients with stage 0-III BC, body mass index ≥25 kg/m2. For RPPA, formalin-fixed paraffin-embedded (FFPE) samples were probed with 160 antibodies. Paired and two-sample t-tests were performed (p ≤ 0.05). Multiple comparisons were adjusted for by fixing the false discovery rate at 25 %. We evaluated whether pre- and post-metformin changes of select markers by RPPA were identified by immunohistochemistry (IHC) in these samples. We also assessed for these changes by western blot in metformin-treated BC cell lines. RESULTS: After adjusting for multiple comparisons in the 32 tumors from metformin-treated patients vs. 34 untreated historical controls, 11 proteins were significantly different between cases vs. CONTROLS: increases in Raptor, C-Raf, Cyclin B1, Cyclin D1, TRFC, and Syk; and reductions in pMAPKpT202,Y204, JNKpT183,pT185, BadpS112, PKC.alphapS657, and SrcpY416. Cyclin D1 change after metformin by IHC was not observed. In cell lines, reductions in JNKpT183 and BadpS112 were seen, with no change in Cyclin D1 or Raptor. CONCLUSIONS: These results suggest that metformin modulates apoptosis/cell cycle, cell signaling, and invasion/motility. These findings should be assessed in larger metformin trials. If confirmed, associations between these changes and BC clinical outcome should be evaluated. CLINICALTRIALS. GOV IDENTIFIER: NCT00930579.

Reproductive risk factors and oestrogen/progesterone receptor-negative breast cancer in the Breast Cancer Family Registry.

BACKGROUND: Oestrogen receptor (ER)- and progesterone receptor (PR)-negative (ER-PR-) breast cancer is associated with poorer prognosis compared with other breast cancer subtypes. High parity has been associated with an increased risk of ER-PR- cancer, but emerging evidence suggests that breastfeeding may reduce this risk. Whether this potential breastfeeding benefit extends to women at high risk of breast cancer remains critical to understand for prevention. METHODS: Using population-based ascertained cases (n=4011) and controls (2997) from the Breast Cancer Family Registry, we examined reproductive risk factors in relation to ER and PR status. RESULTS: High parity (≥3 live births) without breastfeeding was positively associated only with ER-PR- tumours (odds ratio (OR)=1.57, 95% confidence interval (CI), 1.10-2.24); there was no association with parity in women who breastfed (OR=0.93, 95% CI 0.71-1.22). Across all race/ethnicities, associations for ER-PR- cancer were higher among women who did not breastfeed than among women who did. Oral contraceptive (OC) use before 1975 was associated with an increased risk of ER-PR- cancer only (OR=1.32, 95% CI 1.04-1.67). For women who began OC use in 1975 or later there was no increased risk. CONCLUSIONS: Our findings support that there are modifiable factors for ER-PR- breast cancer and that breastfeeding in particular may mitigate the increased risk of ER-PR- cancers seen from multiparity.

PCDH8, the human homolog of PAPC, is a candidate tumor suppressor of breast cancer.

Carcinoma is an altered state of tissue differentiation in which epithelial cells no longer respond to cues that keep them in their proper position. A break down in these cues has disastrous consequences not only in cancer but also in embryonic development when cells of various lineages must organize into discrete entities to form a body plan. Paraxial protocadherin (PAPC) is an adhesion protein with six cadherin repeats that organizes the formation and polarity of developing cellular structures in frog, fish and mouse embryos. Here we show that protocadherin-8 (PCDH8), the human ortholog of PAPC, is inactivated through either mutation or epigenetic silencing in a high fraction of breast carcinomas. Loss of PCDH8 expression is associated with loss of heterozygosity, partial promoter methylation, and increased proliferation. Complementation of mutant tumor cell line HCC2218 with wild-type PCDH8 inhibited its growth. Two tumor mutants, E146K and R343H, were defective for inhibition of cell growth and migration. Surprisingly, the E146K mutant transformed the human mammary epithelial cell line MCF10A and sustained the expression of cyclin D1 and MYC without epidermal growth factor. We propose that loss of PCDH8 promotes oncogenesis in epithelial human cancers by disrupting cell-cell communication dedicated to tissue organization and repression of mitogenic signaling.

HER-2/neu overexpression in uterine papillary serous cancers and its possible therapeutic implications.

Uterine papillary serous carcinoma (UPSC) is a highly aggressive variant of endometrial cancer with features similar to high-grade ovarian cancer. Patients tend to be elderly, thin, have a high grade tumor with extensive extrauterine disease at the time of diagnosis. The transmembrane receptor encoded by the HER-2 cellular oncogene is amplified in several types of human carcinomas and provides an attractive therapeutic target. HER-2/neu, the transmembrane receptor encoded by the c-erbB2 gene, is overexpressed by immunohistochemistry in <25% of ovarian cancers and 20-30% of breast cancers, and <10% of endometrial cancer. There are prognostic and therapeutic implications associated with the overexpression of this transmembrane protein. Herceptin, a humanized murine monoclonal antibody directed against the extracellular domain of the HER-2/neu protein, is being used to treat breast cancer that overexpresses HER-2/neu. We reviewed all patients diagnosed with UPSC between 1999-2001. Twenty-six patients were identified, and 19 patients had specimens available for evaluation. We performed immunohistochemical analysis (Herceptest, Dako, Carpinteria, CA) on 19 paraffin embedded blocks of UPSC tumors looking for HER-2/neu over expression. Five out of 19 (26%) stained heavily (3+) for HER-2/neu receptor protein. Four of these five patients had advanced disease at diagnosis. Two of these patients were subsequently treated with Herceptin; one with complete response and one with stable disease based on CT scan and CA-125 findings. Targeting HER-2/neu may be beneficial for a select group of patients with UPSC. We are continuing to evaluate samples for HER-2/neu over expression by fluorescence in situ hybridization (FISH).

Fighting colorectal cancer: molecular epidemiology differences among Ashkenazi and Sephardic Jews and Palestinians.

BACKGROUND: To evaluate and compare differences in the molecular genetics among high-risk (Ashkenazi Jews), intermediate-risk (Sephardic Jews) and low-risk (Palestinians) groups for colorectal cancer who live in the same geographical region. PATIENTS AND METHODS: The 1995-1996 records from the Tel Aviv Medical Center and Muqased hospital (East Jerusalem) randomly identified patients with colorectal cancer. There were 25 patients from each ethnic group. Epidemiological data were obtained from interviews with the patients and from their hospital charts. The levels of cyclin D1, beta-catenine, p27, p53, Ki-67 and Her-2/neu proteins were determined by immunohistochemistry. The main outcome measures were the association between gene expression and colorectal incidence in the different ethnic groups. RESULTS: Ashkenazi Jews have the highest rate of colorectal cancer, and are diagnosed at an early stage compared with Palestinians (72% and 33% of the cases are in Dukes' A and B, respectively), and, hence, this may explain the better 5-year survival rate among this group. Sephardic Jews are diagnosed at a more advanced stage, the tumors are poorly differentiated and they lack p27. Palestinians have significantly higher cyclin D1 levels. There was a statistically significant inverse correlation between the expression of beta-catenine and cyclin D1, as well as p53 and p27 (P <0.05). CONCLUSIONS: Increased expression of cyclin D1, p53, Ki-67, beta-catenine and Her-2/neu, and decreased expression of p27 may be important events in the three ethnic groups with colorectal cancer. The lower mortality rate among Ashkenazi Jews may be partially explained by their better molecular biology profile.

Proton pump inhibitors reduce cell cycle abnormalities in Barrett's esophagus.

Neoplastic progression in Barrett's esophagus is a multi-step process in which the metaplastic columnar epithelium sequentially evolves through a metaplasia-dysplasia-carcinoma sequence. The expression and DNA copy number of key cell cycle regulatory genes in paired normal and Barrett's esophagus samples was evaluated. Protein levels were evaluated in 60 formalin-fixed, paraffin-embedded human tissues by immunohistochemistry. DNA copy number from 20 fresh tissue pairs was analysed by Southern blot analysis. All normal mucosal samples expressed the p27(kip1) protein, but did not display appreciable nuclear staining for p16(kip4), p21(cip1) or cyclins D1 and E. Barrett's metaplastic specimens displayed increased expression levels of p16(kip4) (74%), p21(cip1) (89%) and cyclins D1 (43%) and E (37%). p27 protein was absent in three cases. There was a significant correlation between the expression of p16(kip4) and cyclin E, and p21(cip1) and p27(kip4) with cyclin D1. DNA analysis did not reveal any amplification or deletion of these genes. Acid suppression, however, was associated with significantly lower expression levels of key cell cycle proteins. Increased expression of key cell cycle regulatory genes appears to occur early in the neoplastic progression associated with Barrett's esophagus. Treatment with proton pump inhibitors appears to alter this increased expression.

Cyclin D1 overexpression is more prevalent in non-Caucasian breast cancer.

African-American women with breast cancer consistently show a shortened survival when compared with Caucasians with breast cancer, however it is not clear whether this is due to socioeconomic factors or to racial differences in tumor biology. Cyclin D1 overexpression has been demonstrated in 60-80% of female breast cancers, however these studies have not included race or ethnicity data. We examined the level of cyclin D1 protein expression in 139 cases of female breast cancer obtained from different ethnic populations. Using an immunoperoxidase-based technique and a polyclonal anti-cyclin D1 antibody, the rate of overexpression was 68%. Cyclin D1 overexpression tended to be more frequent in cases from non-Caucasian patients when compared with those from Caucasian patients (77% vs. 59%, p=0.051). Our findings suggest that non-Caucasian ethnicity may be important in predicting cyclin D1 overexpression. Cyclin D1 could therefore serve as a possible target in managing breast cancer in the African-American population.

Chronic Helicobacter pylori infection induces an apoptosis-resistant phenotype associated with decreased expression of p27(kip1).

Helicobacter pylori infection is associated with the development of gastric cancer. In short-term coculture with AGS gastric cells, H. pylori inhibits cell cycle progression and induces dose-dependent apoptosis. Based on the concept that an imbalance between proliferation and apoptosis may contribute to the emergence of gastric cancer, we chronically exposed AGS cells to H. pylori as a model of chronic exposure in humans. The AGS derivatives selected by this process were stably resistant not only to H. pylori-induced apoptosis but also to apoptosis induced by other enteric bacteria and by several toxic agents including radiation and cancer chemotherapy. Like the parental AGS cells, the derivatives underwent G(1)/S-phase cell cycle inhibition in response to H. pylori. The AGS derivatives displayed a marked decrease in cellular levels of the cell cycle control protein p27(kip1). We found a similar decrease in epithelial cell p27(kip1) expression in gastric biopsy specimens from H. pylori-infected patients. These findings are consistent with observations that link decreases in the p27(kip1) level to increased susceptibility to cancer in mice with p27(kip1) deleted and to a poor prognosis of gastric cancer in humans. This is the first demonstration that bacterial infection can lead to apoptosis resistance and to cross-resistance to other inducers of apoptosis such as bacteria, chemotherapeutic agents, and radiation. The development of apoptosis resistance and downmodulation of p27(kip1) may contribute to the increased risk for gastric cancer observed in humans chronically exposed to H. pylori.

Activation of c-K-ras mutations in human gastrointestinal tumors.

BACKGROUND & AIMS: Ras genes are the most frequently detected oncogenes in human malignancies. Data regarding the frequency of c-K-ras mutations in esophageal, gastric, and small bowel tumors are limited and controversial. METHODS: DNA was extracted from 262 formalin-fixed, paraffin-embedded sections of gastrointestinal samples and tumors, including Barrett's esophagus, esophageal squamous cell carcinomas and adenocarcinomas, and small and large bowel adenomas and adenocarcinomas. The presence of c-K-ras codon 12 mutations was determined using a nonradioactive polymerase chain reaction-based restriction fragment length polymorphism assay. RESULTS: c-K-ras mutations were detected in 1 of 39 (2%) patients with Barrett's esophagus, 1 of 21 (5%) adenocarcinomas, 0 of 27 squamous cell carcinomas of the esophagus, and 1 of 32 (3%) gastric adenocarcinomas. It was also present in 8 of 20 (40%) and 10 of 28 (36%) small bowel adenomas and adenocarcinomas, respectively. Similar numbers were observed in 10 of 25 (40%) large bowel adenomas and 11 of 30 adenocarcinomas (37%). Mutations were not associated with age, gender, histology, grade, stage, location, or mortality. CONCLUSIONS: The frequency of codon 12 c-K-ras mutations in small and large bowel tumors is approximately 10-fold higher than that of tumors in the upper gastrointestinal tract.

The relationship between genetic damage from polycyclic aromatic hydrocarbons in breast tissue and breast cancer.

A number of polycyclic aromatic hydrocarbons (PAH) are widespread environmental contaminants that cause mammary cancer experimentally. We investigated whether exposure and susceptibility to PAH, as measured by PAH-DNA adducts in breast tissue, are associated with human breast cancer. We carried out a hospital-based case-control study using immunohistochemical methods to analyze PAH-DNA adducts in tumor and nontumor breast tissue from cases and benign breast tissue from controls. The subjects were white, African-American and Latina women without prior cancer or treatment, including 119 women with breast cancer and 108 with benign breast disease without atypia. PAH-DNA adducts measured in breast tumor tissue of 100 cases and in normal tissue from 105 controls were significantly associated with breast cancer (OR=4.43, 96% CI 1.09-18.01) after controlling for known breast cancer risk factors and current active and passive smoking, and dietary PAH. There was substantial interindividual (17-fold) variability in adducts overall, with 27% of cases and 13% of controls having elevated adducts. The odds ratio for elevated adducts in tumor tissue compared with control tissue was 2.56 (1. 05-6.24), after controlling for potential confounders. Adduct levels in tumor tissue did not vary by stage or tumor size. Among 86 cases with paired tumor and nontumor tissue, adducts levels in these two tissues were highly correlated (r=0.56, P<0.001). However, the corresponding associations between case-control status and adducts measured in nontumor tissue from 90 cases and in normal tissue from 105 controls were positive but not statistically significant. Overall, neither active nor passive smoking, or dietary PAH were significantly associated with PAH-DNA adducts or breast cancer case-control status. These results suggest that genetic damage reflecting individual exposure and susceptibility to PAH may play a role in breast cancer; but more research is needed to determine whether the findings are relevant to causation or progression of breast cancer.

Immunohistochemical analysis of polycyclic aromatic hydrocarbon-DNA adducts in breast tumor tissue.

Environmental carcinogens may play a role in the etiology of breast cancer, but the extent of their contribution is not yet defined. The aims of this study were to determine whether polycyclic aromatic hydrocarbon (PAH)-DNA adducts could be detected in stored paraffin blocks of breast tumor tissue (n=147) with an immunoperoxidase technique and whether they correlated with smoking history and/or mutant p53 protein expression. There was no significant difference in mean relative nuclear staining intensity in non-smokers (444+/-90, n=75), ever smokers (435+/-91, n=72), and current smokers (456+/-98, n=35). In either current or ever smokers, PAH-DNA adducts were non-significantly elevated in those with greater compared with lower exposure in relation to age at started smoking, years of smoking, cigarettes per day, and pack years. DNA damage levels were not elevated in tissues with compared with those without mutant p53 protein expression. These data demonstrate that immunohistochemical methods can be used to monitor DNA damage levels in archived breast tissues.

Estrogen and progesterone receptor-negative T11 vertebral hemangioma presenting as a postpartum compression fracture: case report and management.

OBJECTIVE AND IMPORTANCE: Pregnancy-related vertebral hemangioma compressive myelopathy is a rare occurrence that tends to arise in the upper thoracic and lower cervical spine, peaks during the third trimester, and remits after parturition. Whether corticosteroid receptors play a role in the pathogenesis of these lesions is unknown. Most of these lesions have been managed with posterior decompression. CLINICAL PRESENTATION: A 29-year-old woman presented with acute-onset lower-extremity weakness and sensory loss immediately after parturition. INTERVENTION: We used a retropleural approach for anterior decompression and fusion, followed by radiation therapy. Immunohistochemical analysis of estrogen and progesterone receptor expression was performed. CONCLUSION: We report an unusual case of lower thoracic postpartum vertebral hemangioma compressive myelopathy caused by a parturition-related compression fracture. Results of tests for corticosteroid receptors were negative, which implicated a hemodynamic rather than hormonal cause for disease progression.

Induction of autophagy and inhibition of tumorigenesis by beclin 1.

The process of autophagy, or bulk degradation of cellular proteins through an autophagosomic-lysosomal pathway, is important in normal growth control and may be defective in tumour cells. However, little is known about the genetic mediators of autophagy in mammalian cells or their role in tumour development. The mammalian gene encoding Beclin 1, a novel Bcl-2-interacting, coiled-coil protein, has structural similarity to the yeast autophagy gene, apg6/vps30, and is mono-allelically deleted in 40-75% of sporadic human breast cancers and ovarian cancers. Here we show, using gene-transfer techniques, that beclin 1 promotes autophagy in autophagy-defective yeast with a targeted disruption of agp6/vps30, and in human MCF7 breast carcinoma cells. The autophagy-promoting activity of beclin 1 in MCF7 cells is associated with inhibition of MCF7 cellular proliferation, in vitro clonigenicity and tumorigenesis in nude mice. Furthermore, endogenous Beclin 1 protein expression is frequently low in human breast epithelial carcinoma cell lines and tissue, but is expressed ubiquitously at high levels in normal breast epithelia. Thus, beclin 1 is a mammalian autophagy gene that can inhibit tumorigenesis and is expressed at decreased levels in human breast carcinoma. These findings suggest that decreased expression of autophagy proteins may contribute to the development or progression of breast and other human malignancies.

Abnormalities in the expression of cell cycle-related proteins in tumors of the small bowel.

Tumors of the small bowel are quite rare for unknown reasons, although they resemble colorectal tumors in many respects. The purpose of this study was to determine whether abnormalities in the expression of several cell cycle control genes are of importance in small bowel tumorigenesis by comparing a series of samples of normal mucosa, adenomatous polyps, and adenocarcinomas. The levels of cyclin D1, cyclin E, p16, p21, p27, and p53 proteins were determined by immunohistochemistry in samples of normal small bowel (n = 16), small bowel adenomas (n = 20), and small bowel adenocarcinomas (n = 24). Normal small bowel mucosa expressed p27 protein, but not the other cell cycle-related proteins. About 20% of the tumors displayed a decrease in the expression of this protein. The most frequent alteration in the tumors was an increase in the p16 protein. Increased expression of p53 was associated with tumor progression because it was overexpressed in 45% of the adenomas and 65% of the adenocarcinomas (P<0.05). Advanced age and increased detection of cyclin D1 and p53 were associated with a decreased 3-year survival (P<0.05). Cell cycle abnormalities are early and important events in the multistep process of small bowel tumorigenesis, thus resembling colorectal carcinogenesis. As in colon cancer, deregulated expression of G1 proteins may perturb cell cycle control in benign adenomas of the small bowel and thereby enhance tumor progression. Increased expression of cell cycle inhibitors in tumors may serve as a defense mechanism for tumor progression.

Increased susceptibility to carcinogen-induced mammary tumors in MMTV-Cdc25B transgenic mice.

Cdc25 phosphatases activate cyclin-dependent kinases (Cdks) by dephosphorylating critical phospho-tyrosine and phospho-threonine residues on these proteins. Several types of studies indicate that Cdc25s can enhance cell proliferation and oncogenesis. Furthermore, overexpression of Cdc25A and/or B have been detected in several types of primary human cancers, including breast cancers. To further assess the oncogenic capacity of Cdc25B in vivo, we have generated transgenic mice that overexpress Cdc25B in the mammary epithelium, driven by the MMTV - LTR promoter. Although these mice are grossly normal for up to 18 months, the ectopic expression of Cdc25B in their mammary glands increases the susceptibility of these mice to induction of mammary tumors by the carcinogen 9,10-dimethyl-1, 2-benzanthracene (DMBA).

Wild-type p53 epitope naturally processed and presented by an HLA-B haplotype on human breast carcinoma cells.

To broaden the clinical applicability of peptide-based immunotherapy in breast cancer, there is a need to identify further tumor-associated peptide epitopes that are specific for HLA alleles, in addition to HLA-A2. The HLA-B44 haplotype is one of the most common HLA-B haplotypes, occurring in 10-20% of the population. We performed the structural characterization of HLA class I-bound self-peptides presented by a human breast cancer cell line with a HLA-A68, A32, B40, B44 haplotype, to identify potential tumor-specific antigens. Of 13 sequenced peptides, 1 peptide had the HLA-A68 peptide binding motif and 12 peptides had the HLA-B40, B44 peptide binding motif. One of the latter peptides, FEVRVCACPG, shared 100% homology to residues 270-279 of wild-type P53 protein. Our study, thus, provides direct evidence for the natural processing and presentation of p53 epitope 270-279 by HLA-B40, B44-bearing human breast tumor cells. Epitopes spanning this region of P53 may have potential use for immunotherapy in patients expressing HLA-A2 and -B44 supertypes.

Overexpression of cyclin D1 occurs in both squamous carcinomas and adenocarcinomas of the esophagus and in adenocarcinomas of the stomach.

Increased expression of the cyclin D1 gene frequently occurs in human squamous carcinomas of the esophagus. However, the expression of cyclin D1 has not been previously examined in detail in adenocarcinomas of the esophagus or stomach. Therefore, we examined, in parallel, the expression of cyclin D1 in both squamous and adenocarcinomas of the esophagus and in adenocarcinomas of the stomach. The level of expression of the cyclin D1 protein was assessed by immunohistochemistry in 39 esophageal and 34 gastric carcinomas and correlated with clinical and pathology parameters. Within the esophagus, 71% of the squamous carcinomas and 64% of the adenocarcinomas were positive for increased cyclin D1 nuclear staining. For adenocarcinomas of the stomach, the overall positive rate was 47%; in the gastric cardia, the rate was 44%, and in other regions of the stomach, it was 50%. In esophageal and gastric adenocarcinomas of the intestinal type, increased expression of cyclin D1 was seen in 70% of the samples, whereas with the diffuse type only 13% were positive (P < .01). Tumors from patients older than the median age of 67 years were more frequently positive than tumors from patients younger than 67 years (74% v 42%, respectively) (P < .01). Positive staining was also seen more frequently in well and moderately differentiated tumors than in poorly differentiated tumors (74% v 49%, respectively) (P < .05). Cytoplasmic staining for cyclin D1 was noted in 22% of the tumors, of various types. Therefore, increased expression of cyclin D1 frequently occurs in both adenocarcinomas and squamous carcinomas of the esophagus, and in adenocarcinomas of the stomach. The increased expression in adenocarcinomas is especially frequent in the intestinal-type lesions.