The expression of Fhit protein is related inversely to disease progression in patients with breast carcinoma

Poly-ligand profiling differentiates trastuzumab-treated breast cancer patients according to their outcomes

Assessing the phenotypic diversity underlying tumour progression requires the identification of variations in the respective molecular interaction networks. Here we report proof-of-concept for a platform called poly-ligand profiling (PLP) that surveys these system states and distinguishes breast cancer patients who did or did not derive benefit from trastuzumab. We perform tissue-SELEX on breast cancer specimens to enrich single-stranded DNA (ssDNA) libraries that preferentially interact with molecular components associated with the two clinical phenotypes. Testing of independent sample sets verifies the ability of PLP to classify trastuzumab-treated patients according to their clinical outcomes with ROC-AUC of 0.78. Standard HER2 testing of the same patients gives a ROC-AUC of 0.47. Kaplan–Meier analysis reveals a median increase in benefit from trastuzumab-containing treatments of 300 days for PLP-positive compared to PLP-negative patients. If prospectively validated, PLP may increase success rates in precision oncology and clinical trials, thus improving both patient care and drug development.

Patients’ selection is particularly important in cancer treatment. Here the authors present a proof-of-principle methodology that could be potentially important in assisting therapeutic decisions in the treatment of breast cancer patients.

Analysis of FHIT gene methylation in egyptian breast cancer women: association with clinicopathological features

BACKGROUND

Fragile histidine triad (FHIT) gene is a tumor suppressor gene which involved in breast cancer pathogenesis. Epigenetics alterations in FHIT contributes to tumorigenesis of breast cancer.

OBJECTIVE

Our objective was to study FHIT promoter region hypermethylation in Egyptian breast cancer patients and its association with clinicopathological features.

MATERIALS AND METHODS

Methylation-specific polymerase chain reaction was performed to study the hypermethylation of FHIT promoter region in 20 benign breast tissues and 30 breast cancer tissues.

RESULTS

The frequency of hypermethylation of FHIT promoter region was significantly increased in breast cancer patients compared to bengin breast disease patients. The Odd ?s ratio (95%CI) of development of breast cancer in individuals with FHIT promoter hypermethylation (MM) was 11.0 (1.22-250.8). There were also significant associations between FHIT promoter hypermethylation and estrogen, progesterone receptors negativity, tumor stage and nodal involvment in breast cancer pateints.

CONCLUSIONS

Our results support an association between FHIT promotor hypermethylation and development of breast cancer in Egyptian breast cancer patients. FHIT promoter hypermethylation is associated with some poor prognostic features of breast cancer.

Fhit Nuclear Import Following EGF Stimulation Sustains Proliferation of Breast Cancer Cells

The tumor-suppressor protein fragile histidine triad (Fhit) exerts its functions in the cytoplasm, although some reports suggest that it may also act in the nucleus. We previously showed that cytosolic Fhit protein levels in cancer cell lines stimulated to proliferate were reduced by proteasomal degradation. Here, we demonstrate that Fhit is physiologically present in the nucleus of breast cancer cell lines and tissues at a low level and that proliferative stimulation increases nuclear levels. Breast cancer cells expressing the FhitY114F mutant, which do not undergo proteasomal degradation, contained mutated Fhit in the nucleus, while cells treated with a proteasome inhibitor accumulated nuclear Fhit during proliferation. Thus, Fhit nuclear shuttling and proteasome degradation phenomena occur independently. When Fhit was coupled to a nuclear localization sequence, the proliferation rate of the transfected cells increased together with levels of proliferation pathway mediators cyclin D1, phospho-MAPK, and phospho-STAT3. Fhit nuclear translocation upon mitogenic stimulation may represent a new regulatory mechanism that allows rapid restoration of Fhit cytoplasmic levels and promotes the proliferation cascade activated by mitogenic stimulation.

SMAD4 expression in breast ductal carcinoma correlates with prognosis

The present study examined SMAD4 expression in fine-needle aspiration cell blocks from patients with breast ductal carcinoma, in order to assess its viability as a prognostic marker. Using immunohistochemistry, the SMAD4 protein status of 86 breast ductal carcinoma fine-needle biopsies, from patients who underwent tumor resection at Beihua University Affiliated Hospital (Jilin, China) between 2002 and 2008, was characterized. The association between SMAD4 expression and clinicopathological parameters, as well as prognosis was assessed using the Mantel-Haenszel method and Cox proportional hazards regression. SMAD4 staining was observed in the cytoplasm and nucleus, and its expression was found to be decreased in ductal breast carcinoma as compared with adjacent normal breast epithelia. Patients with reduced SMAD4 expression levels tended to exhibit more poorly differentiated tumors, a higher risk of recurrence and shorter overall survival. These results demonstrated that the evaluation of SMAD4 protein status in fine-needle biopsy specimens of breast ductal carcinoma may provide additional prognostic information.

Activating transcription factor 3 is overexpressed in human glioma and its knockdown in glioblastoma cells causes growth inhibition both in vitro and in vivo

Glioblastomas are highly malignant gliomas that are extremely invasive with high rates of recurrence and mortality. It has been reported that activating transcription factor 3 (ATF3) is expressed in elevated levels in multiple malignant tumors. The purpose of this study was to investigate the function of ATF3 in the development of glioma and its clinical significance. Immunohistochemical staining, western blot analysis and RT-qPCR revealed that the mRNA and protein levels of ATF3 and matrix metalloproteinase 2 (MMP2) were higher in the glioma than in the normal human brain tissues, and that their levels were proportional to the pathological grades. By contrast, the mRNA and protein levels of mammary serine protease inhibitor (maspin; SERPINB5) were significantly lower in the glioma than in the normal brain tissue, and maspin expression was inversely proportional to the glioma pathological grade. The transfection of U373MG glioblastoma cells with ATF3-siRNA induced a number of changes in cell behavior; the cell proliferative activity was decreased and flow cytometry revealed an increased proportion of cells arrested in the G₀/G₁ phase of the cell cycle. In addition, TUNEL staining indicated an increased proportion of cells undergoing apoptosis and Transwell assays revealed impaired cell mobility. The sizes of the tumors grown as xenografts in nude mice were also significantly reduced by treatment of host mice with ATF3-siRNA. Taken together, these results suggest that ATF3 promotes the progression of human gliomas.

Promoter methylation status of the FHIT gene and Fhit expression: association with HER2/neu status in breast cancer patients

Aberrant DNA methylation has been recognized to contribute to breast carcinogenesis, and promoter hypermethylation of several tumor suppressor genes has been correlated with decreased gene expression. The fragile histidine triad (FHIT) gene is a putative tumor suppressor gene in breast and other types of cancer, and loss of Fhit expression has been observed in breast cancer. The aim of the present study was to evaluate the association between methylation of the FHIT gene and its expression in breast cancer, and to investigate whether methylation and expression of the FHIT gene correlates with clinicopathological characteristics in relation to human epidermal growth factor receptor 2 (HER2) status. Pyrosequencing of bisulfite-treated DNA was performed to study the methylation status of the FHIT gene in 60 breast cancer samples. We examined the expression of Fhit using tissue microarrays by immunohistochemical staining. FHIT methylation was detected in 96.7% and the positive expression rate of Fhit was 87.3% of the patients. The mean methylation level of the FHIT gene was associated with intratumoral inflammation. Methylation level of the FHIT gene had no significant differences according to molecular subtypes. Loss of Fhit expression was associated with large tumor size, basal-like subtype and positive expression of EGFR. In HER2-negative breast cancer, loss of Fhit expression was significantly associated with tumor size, estrogen receptor status and Ki-67 proliferation index. No significant correlation between methylation of the FHIT gene and its expression was observed in the present study. Our results suggest that loss of Fhit expression in breast cancer is associated with poor prognostic features, and it is also relevant to the results in HER2-negative breast cancer. Further studies with larger sample sizes and longer follow-up are required to clarify the predictive and prognostic value of Fhit expression and the FHIT gene methylation status in breast cancer.

High-resolution whole-genome analysis of skull base chordomas implicates FHIT loss in chordoma pathogenesis

Chordoma is a rare tumor arising in the sacrum, clivus, or vertebrae. It is often not completely resectable and shows a high incidence of recurrence and progression with shortened patient survival and impaired quality of life. Chemotherapeutic options are limited to investigational therapies at present. Therefore, adjuvant therapy for control of tumor recurrence and progression is of great interest, especially in skull base lesions where complete tumor resection is often not possible because of the proximity of cranial nerves. To understand the extent of genetic instability and associated chromosomal and gene losses or gains in skull base chordoma, we undertook whole-genome single-nucleotide polymorphism microarray analysis of flash frozen surgical chordoma specimens, 21 from the clivus and 1 from C1 to C2 vertebrae. We confirm the presence of a deletion at 9p involving CDKN2A, CDKN2B, and MTAP but at a much lower rate (22%) than previously reported for sacral chordoma. At a similar frequency (21%), we found aneuploidy of chromosome 3. Tissue microarray immunohistochemistry demonstrated absent or reduced fragile histidine triad (FHIT) protein expression in 98% of sacral chordomas and 67%of skull base chordomas. Our data suggest that chromosome 3 aneuploidy and epigenetic regulation of FHIT contribute to loss of the FHIT tumor suppressor in chordoma. The finding that FHIT is lost in a majority of chordomas provides new insight into chordoma pathogenesis and points to a potential new therapeutic target for this challenging neoplasm.

Epigenetic repression of regulator of G-protein signaling 2 promotes androgen-independent prostate cancer cell growth

G-protein-coupled receptor (GPCR)-stimulated androgen-independent activation of androgen receptor (AR) contributes to acquisition of a hormone-refractory phenotype by prostate cancer. We previously reported that regulator of G-protein signaling (RGS) 2, an inhibitor of GPCRs, inhibits androgen-independent AR activation (Cao et al., Oncogene 2006;25:3719-34). Here, we show reduced RGS2 protein expression in human prostate cancer specimens compared to adjacent normal or hyperplastic tissue. Methylation-specific PCR analysis and bisulfite sequencing indicated that methylation of the CpG island in the RGS2 gene promoter correlated with RGS2 downregulation in prostate cancer. In vitro methylation of this promoter suppressed reporter gene expression in transient transfection studies, whereas reversal of this promoter methylation with 5-aza-2'-deoxycytidine (5-Aza-dC) induced RGS2 reexpression in androgen-independent prostate cancer cells and inhibited their growth under androgen-deficient conditions. Interestingly, the inhibitory effect of 5-Aza-dC was significantly reduced by an RGS2-targeted short hairpin RNA, indicating that reexpressed RGS2 contributed to this growth inhibition. Restoration of RGS2 levels by ectopic expression in androgen-independent prostate cancer cells suppressed growth of xenografts in castrated mice. Thus, RGS2 promoter hypermethylation represses its expression and unmasks a latent pathway for AR transactivation in prostate cancer cells. Targeting this reversible process may provide a new strategy for suppressing prostate cancer progression by reestablishing its androgen sensitivity.

Sequencing and comparative genomic analysis of 1227 Felis catus cDNA sequences enriched for developmental, clinical and nutritional phenotypes

Background

The feline genome is valuable to the veterinary and model organism genomics communities because the cat is an obligate carnivore and a model for endangered felids. The initial public release of the Felis catus genome assembly provided a framework for investigating the genomic basis of feline biology. However, the entire set of protein coding genes has not been elucidated.

Results

We identified and characterized 1227 protein coding feline sequences, of which 913 map to public sequences and 314 are novel. These sequences have been deposited into NCBI's genbank database and complement public genomic resources by providing additional protein coding sequences that fill in some of the gaps in the feline genome assembly. Through functional and comparative genomic analyses, we gained an understanding of the role of these sequences in feline development, nutrition and health. Specifically, we identified 104 orthologs of human genes associated with Mendelian disorders. We detected negative selection within sequences with gene ontology annotations associated with intracellular trafficking, cytoskeleton and muscle functions. We detected relatively less negative selection on protein sequences encoding extracellular networks, apoptotic pathways and mitochondrial gene ontology annotations. Additionally, we characterized feline cDNA sequences that have mouse orthologs associated with clinical, nutritional and developmental phenotypes. Together, this analysis provides an overview of the value of our cDNA sequences and enhances our understanding of how the feline genome is similar to, and different from other mammalian genomes.

Conclusions

The cDNA sequences reported here expand existing feline genomic resources by providing high-quality sequences annotated with comparative genomic information providing functional, clinical, nutritional and orthologous gene information.

Promoter Hypermethylation in Tumor Suppressing Genes p16 and FHIT and Their Relationship with Estrogen Receptor and Progesterone Receptor Status in Breast Cancer Patients from Northern India

BACKGROUND

Aberrant DNA methylation has been recognized in human breast carcinogenesis as a common molecular alteration associated with the loss of expression of a number of key regulatory genes. The present study was undertaken to determine whether methylation and expression of p16 and FHIT genes would correlate with the estrogen receptor (ER) and progesterone receptor (PR) status.

METHODS

Methylation-specific polymerase chain reaction, messenger RNA (mRNA) expression analysis, immunohistochemistry, and Western blot analysis were performed to study the methylation of p16 and FHIT genes in 351 pairs of malignant/normal breast tissues. We examined the expression of ER and PR in those specimens by immunohistochemistry. Mutations of p16 and FHIT genes in tumors were detected by direct sequencing.

RESULTS

The frequency of hypermethylation was 31.9% and 36.8% in p16 and FHIT genes, respectively, and showed significant harmony in concordant hypermethylation (P < .0001). In postmenopausal patients, methylation frequency in both genes is significantly higher in poorly and moderately differentiated tumors. Loss of protein expression of p16 and FHIT in 77 and 74 tumors, respectively, is associated with their methylation status in premenopausal women.

CONCLUSION

We did not find any significant differences in tumor-related gene methylation patterns relevant to both ER and PR status of breast tumors.

Proteome profiling reveals gender differences in the composition of human serum

Proteome analysis using human serum is a technological advancement that will enable the discovery of novel biomarkers and biomarker patterns of various human diseases. Although proteome analysis using serum has potential in disease prevention, early diagnosis and treatment of diseases, and evaluation of pharmacotherapies, this technology is still in its infancy. Thus, we sought to develop an advanced method of conducting proteome analysis on human serum. In this study, we report the development of the semi-comprehensive protein analytical technique, which involves the systematic use of iTRAQ labeling, HPLC, nano-LC and MS. We compared the composition of the serum proteome in males and females using this technique and detected gender-based differences in serum protein composition. This technology will enable the generation of databases that may ultimately lead to the discovery of specific biomarkers or biomarker patterns of various diseases.

Plexin-B1 silencing inhibits ovarian cancer cell migration and invasion

BACKGROUND

Elevated Plexin-B1 expression has been found in diverse human cancers and in non-neoplastic tissues, and it mediates diverse biological and pathological activities. However, whether or not Plexin-B1 expression is involved in human ovarian tumors remains unclear. In the present study, Plexin-B1 expression was explored in benign and malignant human ovarian tumor tissues. In addition, the impact of Plexin-B1 expression on ovarian cancer cell proliferation, migration and invasion were investigated in vitro.

METHODS

Plexin-B1 expression was analyzed in normal and benign ovarian tissues and serous ovarian tumors (both borderline and malignant) by immunohistochemical staining, as well as in four human ovarian cancer cell lines (A2780, C13*, SKOV3, and OV2008) by RT-PCR and western blot analyses. Furthermore, endogenous Plexin-B1 expression was suppressed by Plexin-B1 siRNA in SKOV3 cells, which overexpress Plexin-B1. Protein levels of Plexin-B1, AKT and AKTSer473 were examined by western blot analysis. Cell proliferation, migration and invasion were measured with MTT, wound healing and boyden chamber assays, respectively, and the cytoskeleton was monitored via F-actin staining.

RESULTS

Expression levels of Plexin-B1 protein were significantly higher in serous ovarian carcinomas than in normal ovaries or benign ovarian neoplasms, and in the former, Plexin-B1 expression was positively correlated with lymphatic metastasis, and the membrane and cytoplasm of cancer cells stained positively. SKOV3 cells displayed the highest Plexin-B1 expression at both the mRNA and protein levels among the four tested human ovarian cancer cell lines and was selected as a cell model for further in vitro experiments. Plexin-B1 siRNA significantly suppressed phosphorylation of AKT at Ser473 in SKOV3 cells, but it did not alter total AKT expression. In addition, silencing of Plexin-B1 in SKOV3 cells inhibited cell migration and invasion and reorganized the cytoskeleton, whereas cell proliferation was not affected.

CONCLUSION

Plexin-B1 expression correlates with malignant phenotypes of serous ovarian tumors, probably via phosphorylation of AKT at Ser473, suggesting that Plexin-B1 might be a useful biomarker and/or a novel therapeutic target.

Concomitant loss of heterozygosity at the BRCA1 and FHIT genes as a prognostic factor in sporadic breast cancer

Previous studies have shown loss of heterozygosity (LOH) at the BRCA1 and FHIT genes in sporadic primary breast cancer. The aim of this study was to evaluate concomitant LOH at the BRCA1 and FHIT genes in sporadic breast cancer and investigate its influence on patient survival. Loss of heterozygosity was determined using microsatellite markers. The analysis on the informative cases (n = 72) indicated LOH at both the BRCA1 and FHIT loci in 25 cases (35%), the absence of LOH at both loci in 23 cases (32%), and the presence of LOH at one of the loci in 24 cases (33%). The concomitant LOH was associated with poor prognostic factors, such as large tumors (P = 0.01), axillary nodal involvement (P < 0.01), histologic grade III (P < 0.01), vascular invasion (P = 0.01), and negative hormone receptor (P = 0.02). After a median follow-up period of 48 months, the concomitant LOH group had the shortest survival (P < 0.02 by log-rank test; P < 0.05 by Cox model; hazard ratio of 4.87), compared with patients without LOH. These data suggest that concomitant allelic losses of the BRCA1 and FHIT genes are associated with more aggressive breast tumors.

Low dose radiation-induced adaptive response preventing HPRT mutation is Fhit independent

PURPOSE

To study whether fragile histidine triad (Fhit) prevents IR-induced hypoxanthineguanine phosphoribosyltransferase (HPRT) mutation and whether Fhit plays any role in preventing HPRT mutation through low dose-induced adaptive response.

MATERIALS AND METHODS

Establishing human cell lines with or without Fhit expression by making constructs expressing hemagglutinin (HA) alone or HA-Fhit fusion protein and transfecting the vector to HeLa cells. The effects of Fhit on ionising radiation (IR)-induced mutation were examined by observing HPRT mutation rates in the established cell lines following different doses of IR. The role of Fhit on low dose IR-induced adaptive response were examined by observing HPRT mutation rates in the established cell lines that were exposed to 0.1 Gy and followed with high dose IR or ultraviolet (UV) exposure.

RESULTS

Low dose (0.1 Gy) does not affect HPRT mutation rates in these cell lines. Fhit prevents high dose IR (> or = 2 Gy)-induced mutation as it prevents UV-induced mutation. However, low dose of IR (0.1 Gy)-induced adaptive response prevents both high doses of IR and UV-induced mutation in both the cells with and without Fhit expression.

CONCLUSIONS

Fhit prevents IR-induced HPRT mutation and preventing mutation through low dose of IR-induced adaptive response is Fhit independent.

Hypermethylation of the 5'CpG island of the FHIT gene in clear cell renal carcinomas

FHIT is a tumour suppressor gene which is frequently inactivated in different types of cancer. Both genetic (mutations, deletions, chromosomal rearrangements) and epigenetic (aberrant methylation of the 5'CpG island) alterations of the FHIT gene have been reported in various malignancies. Yet little is known about the mechanism of FHIT inactivation in clear cell renal carcinomas. Since genetic alterations were not frequently observed in DNA corresponding to the FHIT gene in renal tumours, to elucidate the mechanism of FHIT gene silencing we examined 22 paired samples of clear cell renal carcinoma and non-malignant renal tissue for the methylation of the FHIT 5'CpG island by methylation-specific PCR. Hypermethylation of the FHIT 5'CpG island was detected in 54.5% (12/22) of clear cell renal carcinomas. Bisulfite sequencing of the FHIT 5'CpG island confirmed the results obtained by methylation-specific PCR for selected samples. We showed here that expression of the FHIT gene is inversely correlated with hypermethylation of the FHIT 5'CpG island in the selected samples. Our results suggest that hypermethylation of the FHIT 5'CpG island may be responsible for inactivation of the FHIT gene in clear cell renal carcinomas.

Renal Cell Carcinoma Associated with TFE3 Gene Fusion in an Elderly Woman

We present a case report of a renal cell carcinoma with TFE3 overexpression (related to TFE3 gene fusion) in a 63-year-old woman. Such tumors have been reported predominantly in children and young adults, and to our knowledge there are only 2 such cases mentioned in the literature in patients older than ours. However, we believe that this tumor may be underdiagnosed in adults owing to its similarity to clear cell (conventional) carcinoma and in some cases to papillary renal carcinoma.

The expression of FHIT, PCNA and EGFR in benign and malignant breast lesions

Immunohistochemical staining for FHIT and PCNA proteins was carried out in 451 breast lesions showing nonproliferative benign breast disease (BBD) (n=263), proliferative BBD without atypia (n=128), proliferative BBD with atypia (n=11), carcinoma in situ (n=15) or invasive carcinoma (n=34) and for EGFR protein in a subset of 71 of these cases. FHIT underexpression was not detected in nonproliferative lesions, but occurred in 2% of proliferative BBD without atypia, 10% proliferative BBD with atypia, 27% of carcinoma in situ and 41% of invasive carcinoma, which suggests that it could be useful in assessing those carcinoma in situ lesions (ductal, DCIS and lobular, LCIS) that are more likely to progress to malignancy. Preliminary microarray comparisons on DCIS and invasive carcinoma samples dissected from formalin-fixed paraffin sections showed a consistent downregulation of two previously identified FHIT-related genes, caspase 1 and BRCA1 in lesions underexpressing FHIT.

Fragile Histidine Triad Expression in Oral Squamous Cell Carcinoma and Precursor Lesions

PURPOSE

Fragile histidine triad (FHIT) expression in precursor oral lesions (POL) and oral squamous cell carcinomas (OSCC) was studied with regard to (a) the frequency of loss of FHIT expression, (b) whether loss of FHIT expression correlates with degree of dysplasia in POLs, (c) whether FHIT loss predicts high-risk POLs that are more likely to transform, and (d) whether FHIT loss in OSCCs correlates with survival.

EXPERIMENTAL DESIGN

Ninety-four POLs and 86 OSCCs were immunostained for FHIT. Survival analysis was done for cases with validated clinical outcomes.

RESULTS

By optimizing the immunostaining protocol, we found that FHIT is expressed in a distinctive strong nuclear and weak cytoplasmic pattern in oral tissues. Loss of FHIT expression was found in 42 of 94 (45%) POLs and in 66 of 86 (77%) OSCCs. We observed a statistically significant positive correlation between frequency of FHIT loss and increasing grade of dysplasia (chi2=13.8; degrees of freedom=4; P=0.008). Loss of FHIT expression in POLs that progressed to malignancy was more frequent than in those that did not [17 of 25 (68%) versus 12 of 29 (41.4%), respectively]. This difference was statistically significant (chi2=3.8; degrees of freedom=1; P=0.046). In OSCCs, loss of FHIT staining indicated a worse prognosis (survival rate, 36.2%) than when positive FHIT staining was observed (survival rate, 50%), but the difference was not statistically significant (P=0.546, Kaplan-Meier, log-rank).

CONCLUSIONS

FHIT seems to localize to both nuclear and cytoplasmic domains. FHIT inactivation occurs early in oral carcinogenesis and may be useful molecular marker for progressive dysplastic oral lesions.

Prevalence of Fragile Histidine Triad Expression in Tumors from Saudi Arabia: A Tissue Microarray Analysis

AIM

The fragile histidine triad (FHIT) gene was discovered and proposed as a tumor suppressor gene for most human cancers. It encodes the most active common human chromosomal fragile region, FRA3B. We studied the prevalence of loss of FHIT expression in various tumors and correlated its loss with various clinicopathologic features.

METHODS

To determine whether the absence of FHIT expression correlates with clinical variables such as grade, stage, and survival time, we assessed FHIT expression using immunohistochemistry. More than 1,800 tumors from more than 75 tumor categories were analyzed by immunohistochemistry in a tissue microarray format.

RESULTS

Loss of FHIT expression ranged from 19% in ovarian tumors to 67% in lung cancers. Clinical and pathologic features like grade, stage, tumor size, and lymph node metastasis showed correlation with loss of FHIT expression in some tumors. No difference was seen in the survival patterns and loss of FHIT expression in any of the tumor groups studied.

CONCLUSIONS

Loss of FHIT expression is an ubiquitous event in the multistep, multifactorial carcinogenesis process. FHIT may be altered at different stages in different types of cancers. Most of the tumors with a wider prevalence of loss of FHIT expression as an early event show a correlation with clinicopathologic features. However, in some of the tumors, FHIT expression is lost as a late event and is only seen in a fraction of the tumors.

Fhit and CHK1 have opposing effects on homologous recombination repair

Fragile histidine triad (FHIT) gene deletion or promoter methylation and reduced Fhit protein expression occur in approximately 70% of human epithelial tumors and, in some cancers, are clearly associated with tumor progression. Specific Fhit signal pathways have not been identified. We previously reported that compared with Fhit+/+ cells, Fhit-/- cells with an overactivated ATR/CHK1 pathway show increased mutation frequency and resistance to DNA damage-induced killing, indicating that Fhit and the CHK1 pathway have opposing roles in cells responding to DNA damage. In this study, we show that cells, with or without Fhit expression, have similar DNA double-strand break induction levels and similar rejoining rates following ionizing radiation, indicating that the effect of Fhit on cell radiosensitivity is independent of nonhomologous end-joining. By combining I-SceI-induced-DNA double-strand break system and small interfering RNA approach, we also show that knocking down Fhit increases the efficiency of homologous recombination repair of cells, but knocking down Chk1 decreases the efficiency of homologous recombination repair, associated with the sensitivity to ionizing radiation-induced killing. Taken together, the results show that the role of Fhit in affecting the sensitivity of cells to ionizing radiation-induced killing is through the CHK1 pathway linked to homologous recombination repair. These results also illustrate the importance of balanced checkpoint activation in genomic stability and suggest a connection between the radioresistance and mutagenesis, carcinogenesis, as well as tumor progression in Fhit-deficient cells or tissue.

Loss of FHIT expression in breast cancer is correlated with poor prognostic markers

OBJECTIVE

The fragile histidine triad (FHIT) gene is a putative tumor suppressor gene that is thought to be involved in the carcinogenesis of breast cancer. Loss of FHIT expression has been observed in up to 72% of breast cancers and has been associated with increased p53, a high proliferation index, and increased tumor size and grade. However, loss of FHIT expression has not been investigated in association with apoptosis and cyclooxygenase-2 (COX-2) expression in breast cancer. Furthermore, expression of FHIT in primary breast tumors and their metastatic axillary lymph nodes has also not been previously described. The purpose of this study was to evaluate the expression of FHIT, COX-2, bcl-2, and p53 in primary breast tumor tissue; correlate their expression with known clinical and pathologic markers; and in cases when tissue was available, evaluate the expression of FHIT and COX-2 in the corresponding metastatic axillary lymph node in the same patient.

METHODS

Primary breast tumor specimens from 80 patients were examined for the presence of FHIT, COX-2, bcl-2, and p53 expression by immunohistochemistry using standard methods. When tissue was available, the expression of FHIT and COX-2 was also evaluated in the corresponding metastatic axillary lymph node specimen.

RESULTS

FHIT expression in primary breast tumors was 56%. There was a significant correlation between FHIT expression in primary breast tumor and bcl-2 expression (P = 0.017). We also observed a significant inverse correlation between FHIT expression in primary breast tumor tissue and p53 expression (P = 0.023) in lymph node-negative cases. A significant inverse correlation between FHIT expression in the primary tumor and Ki-67 (P = 0.009) was also observed in lymph node-negative cases. FHIT expression in primary tumors correlated with FHIT expression in the metastatic lymph node (52.5%; P = 0.001). FHIT expression in primary tumors did not correlate with COX-2 expression.

CONCLUSION

Our results suggest that loss of FHIT expression in breast cancer is associated with poor prognostic features. Furthermore, loss of FHIT expression is also seen in metastatic axillary lymph node. The prognostic and predictive value of these findings needs to be further evaluated in larger trials with longer follow-up.

Chromosomal instability in oral cancer cells

Chromosomal instability is a common feature of human tumors, including oral cancer. Although a tumor karyotype may remain quite stable over time, chromosomal instability can lead to 'variations on a theme' of a clonal cell population, often with each cell within a tumor possessing a different karyotype. Thus, chromosomal instability appears to be an important acquired feature of tumor cells, since propagation of such a diverse cell population may facilitate evasion of standard therapies. There are several sources of chromosomal instability, although the primary causes appear to be defects in chromosomal segregation, telomere stability, cell-cycle checkpoint regulation, and the repair of DNA damage. Our understanding of the biological basis of chromosomal instability in cancer cells is increasing rapidly, and we are finding that the seemingly unrelated origins of this phenomenon may actually be related through the complex network of cellular signaling pathways. Here, we review the general causes of chromosomal instability in human tumors. Specifically, we address the state of our knowledge regarding chromosomal instability in oral cancer, and discuss various mechanisms that enhance the ability of cancer cells within a tumor to express heterogeneous karyotypes. In addition, we discuss the clinical relevance of factors associated with chromosomal instability as they relate to tumor prognosis and therapy.

Fragile genes as biomarkers: epigenetic control of WWOX and FHIT in lung, breast and bladder cancer

This study aimed to (a) determine if DNA methylation is a mechanism of WWOX (WW domain containing oxidoreductase) and FHIT (fragile histidine triad) inactivation in lung, breast and bladder cancers; (b) examine distinct methylation patterns in neoplastic and adjacent tissues and (c) seek correlation of methylation patterns with disease status. Protein expression was detected by immunohistochemistry, and methylation status by methylation-specific PCR (MSP) and sequencing, in lung squamous cell carcinomas and adjacent tissues, invasive breast carcinomas, adjacent tissues and normal mammary tissues and bladder transitional cell carcinomas. Wwox and Fhit expression was reduced in cancers in association with hypermethylation. Differential patterns of WWOX and FHIT methylation were observed in neoplastic vs adjacent non-neoplastic tissues, suggesting that targeted MSP amplification could be useful in following treatment or prevention protocols. WWOX promoter MSP differentiates DNA of lung cancer from DNA of adjacent lung tissue. WWOX and FHIT promoter methylation is detected in tissue adjacent to breast cancer and WWOX exon 1 MSP distinguishes breast cancer DNA from DNA of adjacent and normal tissue. Differential methylation in cancerous vs adjacent tissues suggests that WWOX and FHIT hypermethylation analyses could enrich a panel of DNA methylation markers.

Involvement of the Fhit gene in the ionizing radiation-activated ATR/CHK1 pathway

Fragile Histidine Triad (Fhit) gene deletion, methylation, and reduced Fhit protein expression occur in about 70% of human epithelial tumors and, in some cancers, are clearly associated with tumor progression. Specific Fhit signal pathways have not been identified, although it has been shown that Fhit overexpression leads to apoptosis in many cancer cell lines. We report in this study that Fhit-/- cells derived from gene knockout mice show much stronger S and G2 checkpoint responses than their wild type counterparts. The strong checkpoint responses are regulated by the ATR/CHK1 pathway, which contributes to the radioresistance of Fhit-/- cells. These results indicate an association of Fhit gene inactivation with increased survival after DNA damage, which is related to the over-active checkpoints regulated by the ATR/CHK1 pathway. These results also suggest the potential effects of Fhit-dependent DNA damage response on tumor progression.

Gene expression profile of an adenomyoepithelioma of the breast with a reciprocal translocation involving chromosomes 8 and 16

Myoepithelium is an integral part of the mammary ductal and lobular architecture, positioned between luminal cells and the basement membrane. We describe the first report on cytogenetic findings in an adenomyoepithelioma of the breast with a balanced t(8;16)(p23;q21), and provide gene expression profile using Affymetrix GeneChip U95AV2 (Affymetrix, Santa Clara, CA). Differential analysis identified 857 genes with 2-fold or more mRNA change in comparison to pooled normal breast control; immunohistochemical analysis was used to confirm these results in a limited number of genes. Expression results were grouped based on the chromosomal location of the genes and associated protein function, and identified several potential pathogenetic mechanisms (autocrine and paracrine growth stimuli) in the development of myoepithelial tumors.

Loss of heterozygosity in normal breast epithelial tissue and benign breast lesions in BRCA1/2 carriers with breast cancer

Loss of heterozygosity (LOH) of the wild-type BRCA1/2 allele is a reproducible event in breast tumors of BRCA1/2 mutation carriers, but it is unknown if this allelic loss occurs only in association with recognizable histopathologic abnormalities. We evaluated the early genomic changes that occur in the mammary glands of patients with increased predisposition to breast cancer due to germline mutations in the BRCA1/2 genes. We tested the hypothesis that these genomic changes may be detected, not only in histologically abnormal and malignant breast tissues, but also in morphologically normal tissues and in areas with pathologically benign changes. Samples were obtained from five breast cancer patients: four BRCA1 carriers and one BRCA2 carrier. In each case, nontumor tissue areas surrounding the tumor or from other locations of the breast were isolated using laser capture microdissection. We evaluated 29 areas showing normal terminal ductal lobular units (TDLUs) or histopathologically benign changes (in particular, sclerosing adenosis), using a panel of polymorphic dinucleotide microsatellite markers for the BRCA1 gene and other chromosome 17 loci, for the BRCA2 gene and other chromosome 13 loci, and for the FHIT gene on 3p14.2. Overall, we analyzed a total of 105 samples of nontumor tissues; LOH was detected in 59 of the 105 (56%). In the normal TDLUs, 15 of 30 samples (50%) showed LOH; in the tissues with benign proliferative changes, such as sclerosing adenosis, 44 of 75 samples showed LOH (59%). Our results suggest that there is a field effect of early genetic events preceding morphologic changes in the mammary glands of BRCA mutation carriers.

Apoptosis incidence and protein expression of p53, TGF-beta receptor II, p27Kip1, and Smad4 in benign, premalignant, and malignant human prostate

Deregulation of apoptosis is involved in prostate cancer development and progression. This study involved an immunohistochemical "profiling" of prostate tissue specimens from patients who underwent prostatectomy for localized prostate cancer, to identify apoptosis-specific alterations associated with premalignant precursor lesions. Prostate tissue was pathologically evaluated, and areas of benign acini, high-grade prostate intraepithelial neoplasia (HGPIN), and prostate cancer were identified. Immunohistochemical analysis was performed to determine the expression of p27Kip1, a key cell cycle regulator, transforming growth factor (TGF)-beta receptor II (TbetaRII), a critical signaling effector of TGF-beta; Smad4, a downstream intracellular effector of TGF-beta signaling; p53, a key apoptosis regulator; and prostate-specific antigen (PSA), a clinical marker of prostate cancer. The apoptotic index of the same cell populations was determined using the transferase-mediated digoxigenin-tagged 16-desoxy-uridine-triphosphate nick end labeling assay. Our findings indicate a significant reduction in p27Kip1 immunoreactivity in HGPIN (P<0.0001) and prostate cancer (P<0.0001) compared with the benign tissue. A significant down-regulation was detected in TbetaRII expression in HGPIN and prostate cancer compared with benign prostatic hyperplasia (BPH)(P<0.001). A significant decrease was also observed in Smad4 levels in HGPIN and prostate cancer compared with BPH (P<0.001). Evaluation of the incidence of apoptosis revealed a significant decrease in the apoptotic index among the epithelial cell populations in HGPIN and a further decrease in prostate carcinoma (P<0.01). This reduced apoptotic index correlated with a significant increase in p53 immunoreactivity in the prostatic carcinoma foci. Prostate cancer cells exhibited strong nuclear staining for p53 compared with adjacent HGPIN (P<0.05) and the benign lesions of the same prostate specimens (P<0.05). A significant reduction in PSA immunostaining was detected in HGPIN and prostate carcinoma foci compared with the benign glandular epithelia (P<0.001). These results further define deregulation of TGF-beta signaling effectors as a molecular basis for loss of apoptotic control contributing to the development of prostate tumors. Identification of apoptotic regulators in precursor premalignant lesions may have prognostic significance in disease progression as well as therapeutic value for targeting prostate cancer.

Alteration of the fragile histidine triad gene early in carcinogenesis: an update

An association between common chromosome fragile sites and frequent chromosomal deletions in cancer has been observed and led to the hypothesis that genes at fragile sites may play a role in tumor development. In 1996, the human fragile histidine triad gene, FHIT, was identified by positional cloning at 3p14.2, a chromosomal region spanning the carcinogen-sensitive, common fragile site FRA3B. FHIT gene is lost and inactivated in a large fraction of tumors and early in carcinogenesis. A group of ancestral cancerous cells that carry FHIT alterations, expanding in succeeding cell generations, exhibits a hallmark in carcinogenesis scenario.

Tamoxifen-associated malignant endometrial tumors: pathologic features and expression of hormone receptors estrogen-alpha, estrogen-beta and progesterone; a case controlled study

OBJECTIVE

Expression analysis of estrogen receptor-beta (ER-beta) and estrogen receptor-alpha (ER-alpha) in tamoxifen-associated malignant endometrial tumors (TAMET) has not previously been published. Antiestrogens complexed with ER-beta have been reported to result in activation of the activator protein-1 (AP-1) pathway that may result in cell proliferation and tumor growth. In this study, the pathologic features and expression of ER-alpha, ER-beta and progesterone receptor (PR) in TAMET were determined and compared to matched cases of non-tamoxifen-associated endometrial cancers.

METHODS

TAMET (n = 33) were evaluated for pathologic features (tumor type, grade, depth of myometrial invasion, lymphvascular space invasion and lymph node status), expression of ER-alpha, ER-beta and PR, and survival data (mean follow-up: 28.7 months). Each case was matched to two control patients with spontaneous endometrial cancers according to tumor type, grade and stage as well as patient age and weight (mean follow-up: 51.5 months). Formalin-fixed paraffin-embedded tissue sections were immunostained with anti-ER-alpha (1D5, Dako, Carpinteria, CA) and anti-PR (PgR636, Dako). Expression scores were determined as a sum of the product of staining intensity and proportion of cells staining (H-score). Deparaffinized sections of tumor were microdissected followed by RNA isolation. Quantification of ER-beta mRNA was performed by real-time quantitative RT-PCR with results expressed as a percentage of beta-actin mRNA.

RESULTS

Of the 33 cases 20 were endometrioid (8 grade 1, 10 grade 2, 2 grade 3), 9 papillary serous and 4 malignant mullerian mixed tumors. Using a multivariate conditional regression model, TAMET had lower ER-alpha expression (P = 0.018), higher PR expression (P = 0.029), and more frequent expression of ER-beta (P = 0.032) as compared to control cases. Cases with TAMET had more deaths from cancer and significantly worse survival from disease than controls (P = 0.01 by a log rank test).

CONCLUSION

TAMET are characterized by a lower expression of ER-alpha, higher expression of PR and more frequent expression of ER-beta as compared to spontaneous tumors. Differential expression of ER-alpha and ER-beta may alter the expression of key target genes (such as those induced by AP-1-dependent gene transcription), and contribute to the pathogenesis and clinical behavior of these tumors. Survival from disease was significantly worse for cases with TAMET as compared to controls.

The fragile genesFHIT andWWOX are inactivated coordinately in invasive breast carcinoma

BACKGROUND

FHIT and WWOX are a tumor suppressor and a candidate suppressor that encompass the FRA3B and FRA16D fragile sites at chromosomes 3p14.2 and 16q23.3-24.1, respectively. Reduced or absent Fhit expression has been reported in two-thirds of invasive breast tumors in association with adverse prognostic factors. Loss of 16q has been reported frequently in low-grade, invasive breast tumors.

METHODS

Expression of Fhit and Wwox was evaluated by immunohistochemical staining in 97 archived breast carcinoma specimens. Expression levels were analyzed for correlations with each other, as well as with various patient and tumor characteristics.

RESULTS

Reduced Fhit and Wwox expression in tumors was observed in 54.6% and 63.2% of specimens, respectively. Fhit and Wwox expression were correlated strongly (P = 0.001). Reduced Fhit staining was seen more frequently in premenopausal patients (P = 0.010), estrogen receptor (ER)-negative or scantly ER-positive tumors (P = 0.058 borderline), high-grade tumors (P = 0.005), and tumors with metastases (P = 0.041). Reduced Wwox staining was more common in tumors with less favorable ER status (P = 0.033). Wwox expression in normal tissue was reduced in 32.9% of specimens, especially in patients with higher stage disease (P = 0.033). Severely reduced Wwox staining (extent < 10%) in normal tissue was found only in postmenopausal women, but reduced Wwox staining (11-75%) was more common in premenopausal women (P = 0.012). Tumor status, lymph node status, and intensity of Fhit expression in tumors were related independently to survival (P = 0.003, P < 0.001, and P = 0.046, respectively).

CONCLUSIONS

The strong correlation observed between Fhit and Wwox expression was consistent with the common elevated susceptibility of fragile sites to DNA damage. Reduced Fhit expression is associated with adverse prognostic factors. The current results suggest that Wwox also has an important and complex association with steroid hormone expression and breast carcinogenesis.

Uterine sarcomas express KIT protein but lack mutation(s) in exon 11 or 17 of c-KIT

OBJECTIVE

Several tumors express the protein product of the protooncogene c-KIT. Some of these respond to imatinib mesylate, a tyrosine kinase inhibitor. The tumors that respond frequently have mutation(s) in exon 11 of c-KIT that encodes for the regulatory juxtamembrane helix. Some tumors that express KIT protein have mutation(s) in exon 17 of c-KIT; however, these do not respond to imatinib mesylate. This investigation was performed to determine the expression of KIT protein and mutational status of exons 11 and 17 of c-KIT in uterine sarcomas.

METHODS

Twenty-five uterine sarcomas treated from 1990 to 2002 were evaluated. These included 14 malignant mullerian mixed tumors (MMMT), 7 leiomyosarcomas (LMS), 2 endometrial stromal sarcomas (ESS), and 2 high-grade heterologous sarcomas (HGHS). Formalin-fixed, paraffin-embedded tissue sections were immunostained with anti-KIT antibody (Santa Cruz Biotechnology, Santa Cruz, CA) with a semiquantitative assessment. Normal myometrium when present in the section was used as an internal negative control. Areas of tumor were microdissected followed by DNA extraction, polymerase chain reaction (PCR) amplification of exons 11 and 17, single-strand conformational polymorphism (SSCP), and DNA sequencing to detect the presence of mutation(s).

RESULTS

All 25 tumors expressed KIT protein at varying levels as assessed by immunohistochemistry. The staining was diffuse and of moderate to strong intensity in 22 tumors. In three tumors (one of each type except MMMT) the staining intensity was weak. In MMMT the epithelial and sarcomatous foci stained similarly. No mutation(s) in exons 11 or 17 of c-KIT were identified in 24/25 tumors. One LMS had deletion of both exons 11 and 17.

CONCLUSIONS

Although uterine sarcomas express KIT protein, they lack KIT-activating mutation(s) in exon 11 or 17 of c-KIT. Therefore, these tumors are unlikely to respond to imatinib mesylate.

Loss of FHIT protein expression is a marker of adverse evolution in good prognosis localized breast cancer

The FHIT tumor suppressor gene, which encompasses the fragile site FRA3B at 3p14.2, is altered frequently in many types of human cancers. To determine its importance as a prognostic marker in breast cancer, the expression of the FHIT protein was studied in a series of 452 breast carcinomas by using immunohistochemistry on sections of tissue microarrays. Three distinct levels of FHIT expression were observed: in 154 cases (34.1%) expression was unchanged as compared to normal level; in 78 (17.2%) no expression was found; in the remaining 220 cases (48.7%), expression was intermediate. Overall, two-thirds of the cases had abnormal levels of the protein. Absence of FHIT was significantly associated with a higher grade (p < 0.01) and absence of hormone receptors (p < 0.001). The patients were separated into Group I (153 node-negative good prognosis patients who did not receive adjuvant chemotherapy) and Group II (226 high-risk patients treated by adjuvant chemotherapy) according to the St.-Gallen conference consensus. The median follow-up was 48 months. Among Group I but not Group II patients, a multivariate analysis showed that FHIT expression was significantly associated with disease-free survival. The relative risk of recurrence for FHIT-negative Group I patients was 2.37 (1.21-4.64; p = 0.03). Thus, among the patients who present with tumors of apparent good prognosis, FHIT is an independent prognostic factor that distinguishes a subgroup of patients who could benefit from adjuvant treatment.

FHIT: from gene discovery to cancer treatment and prevention

Chromosomal abnormalities, including homozygous deletions and loss of heterozygosity, are among the most common features of human tumours. The short arm of human chromosome 3, particularly the region 3p14.2, is a major site of such rearrangements. The 3p14.2 region spans the most active common fragile site of the human genome, encompassing a familial-kidney-cancer-associated breakpoint and a papilloma virus integration site. 6 years ago, the FHIT gene was identified in this region. Subsequent studies have shown that FHIT is commonly the target of chromosomal aberrations involving the long arm of human chromosome 3 and is thereby inactivated in most of the common human malignant diseases, including cancers of the lung, oesophagus, stomach, breast, and kidney. During the past 5 years, evidence has accumulated in support of a tumour-suppressor function for FHIT. In this review, we describe the recent findings in the molecular biology of FHIT with particular focus on the opportunities for treatment and prevention of cancer that have emerged.

Expression of CD95 (Fas) in sun-exposed human skin and cutaneous carcinomas

BACKGROUND

Carcinomas of the skin are by far the most common human malignancies. Continuous exposure to ultraviolet (UV) light facilitates the development of precancerous lesions (actinic keratosis [AK]) that may progress to invasive squamous carcinomas. Apoptosis, triggered by the activation of CD95 (Fas), is one of the most important defense mechanisms against UV light-induced carcinogenesis in experimental models, but the dynamics of CD95 expression in patients with sun-induced lesions are largely unknown.

METHODS

The authors studied the expression of CD95 (Fas) in biopsy samples of normal skin (not exposed to sun) and compared it with chronically sun-exposed skin (as evidenced by solar elastosis), AK, squamous cell carcinoma (SCC) and basal cell carcinoma (BCC), and keratoacanthomas (KA).

RESULTS

Normal skin keratinocytes expressed CD95 in cytoplasmic membranes and intercellular bridges in the basal layer. In chronically sun-exposed keratinocytes (solar elastosis, no evidence of dysplasia), CD95 expression was up-regulated and was observed throughout the entire thickness of the epidermis. However, in actinic keratosis there was a complete absence of Fas in approximately two-thirds of the cases (8 of 12). In invasive SCC, CD95 was expressed focally and weakly only at the sites of contact with stromal lymphocytes. Keratoacanthomas consistently expressed CD95 at the interface with the inflammatory cells. No staining was observed in BCC.

CONCLUSIONS

CD95 (Fas) up-regulation in chronically sun-exposed keratinocytes indicates an important role in the control of sun-induced damage. Further sun exposure results, however, in significant down-regulation of this defense mechanism, proportional to the degree of dysplasia.

Early growth response-1 gene: potential radiation response gene marker in prostate cancer

This study was undertaken to determine whether the transcription factor EGR-1 expression: (1) in the primary tumor, correlates with radiation response in terms of complete local tumor control with no evidence of disease or recurrence and no evidence of metastasis; (2) in the postirradiated biopsies correlates with residual tumor; and (3) correlates with the expression of Egr-1 target genes such as TP53, pRB, and Bax. The authors analyzed: (1) 25 pretreated surgically resected paraffin-embedded primary adenocarcinomas of the prostate for the presence of EGR-1 expression and mutation, and correlated this with clinical endpoints such as serum prostate-specific antigen levels and current clinical status; (2) 27 postirradiated biopsies of prostate for the presence of EGR-1 expression, and correlated these findings to the residual tumor status; and (3) 12 prospective prostate tumor specimens for EGR-1 expression and its target genes. EGR-1 expression was determined by immunohistochemistry and mutations were screened in two regions of the Egr-1 gene (trinucleotide AGC repeats in transactivation domain [TD] and poly A tract in 3'UTR) by polymerase chain reaction-single strand conformational polymorphism analysis. Of 25 patients, 18 patients showed expression of EGR-1. EGR-1 overexpression correlated with treatment failure. No correlation with EGR-1 overexpression and its target genes was found, which may indirectly suggest that overexpressed EGR-1 may lack transactivation function. In summary, EGR-1 overexpression in the mutant form may provide an indication of clinical failure (local recurrence or metastasis).

FHIT alterations in breast cancer

The FHIT gene encodes a diadenosine hydrolase and may be involved in growth control pathways of the cell. Studies on protein-protein interactions, cell lines, including tumourigenicity tests, and knockout mice suggest that the Fhit protein is involved in cell proliferation and apoptosis, and might act as a tumour suppressor. In several different cancers, including breast cancer, alterations in the FHIT gene have been detected in high frequency. The most common alterations are: deletions, DNA hypermethylation, abnormal transcripts and reduced expression at RNA and protein level. The FHIT gene is located at the FRA 3B fragile site at chromosome 3p 14.2, and alterations in the FHIT gene and Fhit protein have been found associated with genome instability, particularly in BRCA 2 mutated breast tumours. This paper will focus on some of the functional aspects of the Fhit protein with respect to tumour pathogenesis and on aberrations detected in breast cancer.

High-resolution chromosome 3p allelotyping of breast carcinomas and precursor lesions demonstrates frequent loss of heterozygosity and a discontinuous pattern of allele loss

We performed high-resolution allelotyping for loss of heterozygosity (LOH) analysis on microdissected samples from 45 primary breast cancers, 47 mammary preneoplastic epithelial foci, and 18 breast cancer cell lines, using a panel of 27 polymorphic chromosome 3p markers. Allele loss in some regions of chromosome 3p was detected in 39 of 45 (87%) primary breast tumors. The 3p21.3 region had the highest frequency of LOH (69%), followed by 3p22-24 (61%), 3p21.2-21.3 (58%), 3p25 (48%), 3p14.2 (45%), 3p14.3 (41%), and 3p12 (35%). Analysis of all of the data revealed at least nine discrete intervals showing frequent allele loss: D3S1511-D3S1284 (U2020/DUTT1 region centered on D3S1274 with a homozygous deletion), D3S1300-D3S1234 [fragile histidine triad (FHIT)/FRA3B region centered on D3S1300 with a homozygous deletion], D3S1076-D3S1573, D3S4624/Luca2.1-D3S4597/P1.5, D3S1478-D3S1029, D3S1029 (with a homozygous deletion), D3S1612-D3S1537, D3S1293-D3S1597, and D3S1597-telomere; it is more than likely that additional localized regions of LOH not examined in this study also exist on chromosome 3p. In multiple cases, there was discontinuous allele loss at several 3p sites in the same tumor. Twenty-one of 47 (45%) preneoplastic lesions demonstrated 3p LOH, including 12 of 13 (92%) ductal carcinoma in situ, 2 of 7 (29%) apocrine metaplasia, and 7 of 25 (28%) usual epithelial hyperplasia. The 3p21.3 region had the highest frequency of LOH in preneoplastic breast epithelium (36%), followed by 3p21.2-21.3 (20%), 3p14.2/FHIT region (11%), 3p25 (10%), and 3p22-24 (5%). In 39 3p loci showing LOH in both the tumor and accompanying preneoplasia, 34 (87%) showed loss of the same parental allele (P = 1.2 x 10(-6), cumulative binomial test). In addition, when 21 preneoplastic samples showing LOH were compared to their accompanying cancers, 67% were clonally related, 20% were potentially clonally related but were divergent, and 13% were clonally unrelated. Overall this demonstrated the high likelihood of clonal relatedness of the preneoplastic foci to the tumors. We conclude that: chromosome 3p allele loss is a common event in breast carcinoma pathogenesis; involves multiple, localized sites that often show discontinuous LOH with intervening markers retaining heterozygosity; and is seen in early preneoplastic stages, which demonstrate clonal relatedness to the invasive cancer.

Altered gene expression in immunogenic poorly differentiated thyroid carcinomas from RET/PTC3p53-/- mice

Cancers develop and progress via activation of oncogenes and loss of tumor suppressor genes, a progression that can be recapitulated through cross breeding mouse strains harboring genetic mutations. To define the role of RET/PTC3, p53 and Fhit in thyroid carcinogenesis, we intercrossed RET/PTC3 transgenics with p53-/- mice. This new strain, RET/PTC3p53-/-, succumb to rapidly growing and strikingly large multilobed thyroid tumors containing mixtures of both well and poorly differentiated, highly proliferative follicular epithelial cells. Interestingly, transplanted tumors from RET/PTC3p53-/- mice grew in SCID but not syngeneic immunocompetent mice indicating that these advanced tumors were immunogenic. RET/PTC3 protein expression was reduced to undetectable levels in tumors of older mice suggesting that the continued elevated expression of RET/PTC3 may not be necessary for tumor progression. Similarly, expression of Fhit protein was reduced in early tumors and undetected in older tumors irrespective of tumor histopathology. In contrast to RET/PTC3p53-/- mice, RET/PTC3Fhit-/- mice did not develop advanced thyroid carcinomas. These studies support a model of human thyroid cancer whereby thyroid epithelium expresses RET/PTC3 protein at early stages of tumor development, followed by the reduction of RET/PTC3 and loss of p53 function with progressive reduction of Fhit protein expression coincident with malignant progression.

Ossifying fibromyxoid tumor of soft parts: report of a case with novel cytogenetic findings

A slowly growing tumor of the left thenar region in a 40-year-old man had the classic features of an ossifying fibromyxoid tumor of soft parts, including an incomplete shell of lamellar bone; a center composed of nodular aggregates of small spindled, oval, and stellate cells in abundant myxoid stroma; and strong expression of vimentin, S-100, and neuron-specific enolase by the tumor cells. Clonal chromosomal abnormalities included loss of a chromosome 6, extra material of unknown origin attached to the long arm of chromosome 12, and an unbalanced translocation involving the short arm of a chromosome 6 and the long arm of a chromosome 14. The karyotype was interpreted as 45,XY, der(6;14)(p10;q10),add(12)(q24.3). The chromosomal abnormalities suggest osteochondroblastic rather than neuronal or schwannian lineage.