Abstract P2-07-13: TP53 gene polymorphisms (c.[215G>C]) in breast cancer patients and predisposition to family cancers- Single center experience

Introduction: Somatic mutations in the TP53 gene are one of the most frequent alterations in human cancers, and germline mutations are the underlying cause of Li-Fraumeni syndrome, which predisposes to a wide spectrum of early-onset cancers. The aim of this study was to evaluate the association between TP53 gene polymorphisms (c.[215G>C]) and predisposition to family cancers. Methods: We reviewed the medical records of 89 (21% TP53 gene homozygotes and 79% heterozygotes) breast cancer patients who were diagnosed and treated in COI in Gliwice. The history of family cancers was colected from medical history. Mutation profile was assessed by RFLP-PCR technique. We evaluatedthe presence ofpolymorphism TP53 (c.[215G>C]). Statistical analysis was carried out using STATISTICA 7 software. Results: Cancers in family history were detected in 72% of pts with TP53 polymorphisms and they were observed insignificantly more often in heterozygotes than in homozygotes (76% vs. 58%, p=0.153). The most frequently reported cancers were: breast cancer (33%), lymphoma (17%), colorectal cancer (9%), OUN cancer (8%), gastric cancer (8%), pancreatic cancer (7%), ovarian cancer (6%) and renal cancer (3%). In analyzed group, renal cancers in family were detected more frequently in TP53 homozygotes than in heterozygotes (16% vs. 0, p=0.008). Similarly, there was also observed tendency to the presence of colorectal cancer in TP53 homozygotes (11% vs. 0, p=0.193). Ovarian cancers and cholangiocarcinomas in family were also observed insignificantly more often in homozygotes than in heterozygotes (7% vs. 0, p=0.580) and (5% vs. 1%, p=0.383). There was no association between number of cancers in family and TP53 polymorphisms (47% vs. 43%, p=0.797). Conclusion: TP53 polymorphism (c.[215G>C]) predisposed to development renal and colorectal cancers (TP53 homozygotes) and ovarian cancer or cholangiocarcinoma (TP53 heterozygotes) in family.

Citation Format: Huszno J, Grzybowska E, Nycz Bochenek M, Pamula Pilat J, Tecza K, Nowara E. TP53 gene polymorphisms (c.[215G>C]) in breast cancer patients and predisposition to family cancers- Single center experience [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P2-07-13.

Gene expression profiles in three histologic types, clear-cell, endometrioid and serous ovarian carcinomas

Ovarian carcinoma is the most lethal type of gynecologic malignancy in the Western world. Majority of early stage ovarian cancers are asymptomatic and this is the main reason that more than two-thirds of patients are diagnosed with advanced disease. Ovarian tumors are heterogeneous and the different histologic subtypes are further classified as benign, borderline (low-grade) and malignant (high-grade) to reflect their behavior. The aim of the study was to analyze gene expression profiles in three histologic types of ovarian carcinoma in an attempt to find the molecular differences among serous, endometrioid and clear cell subtypes. The analysis of gene expression was performed on 57 samples of ovarian carcinoma. RNA was isolated from the ovarian cancer tissues. The gene expression changes were determined by microarray analysis and quantitative real time polymerase chain reaction (qRT-PCR). Measurement of relative gene expression levels was used to identify molecular differences among three histologic types of ovarian carcinoma (clear-cell, endometrioid and serous). Unsupervised statistical analysis revealed four biological subtypes among three histotypes under study. The endometrioid ovarian carcinoma was divided into two molecular subtypes. The biggest molecular differences were observed between clear-cell and serous carcinomas (1070 genes, FDR 0.05), the smallest between endometrioid and serous carcinomas (81 genes, FDR 0.05). The biggest group of differentially expressed genes was involved in transport and metabolism. This finding can explain the differences in the response to chemotherapy observed among different histologic types of ovarian carcinomas. In conclusion, we found TCF2 (HNF1B) gene as a suitable marker for ovarian clear cell carcinoma. Gene expression profiling also shed light on the molecular mechanisms of different chemoresistance among the analyzed histotypes.

Combined effect of low-penetrant SNPs on breast cancer risk

BACKGROUND

Although many low-penetrant genetic risk factors for breast cancer have been discovered, knowledge about the effect of multiple risk alleles is limited, especially in women <50 years. We therefore investigated the association between multiple risk alleles and breast cancer risk as well as individual effects according to age-approximated pre- and post-menopausal status.

METHODS

Ten previously described breast cancer-associated single-nucleotide polymorphisms (SNPs) were analysed in a joint European biobank-based study comprising 3584 breast cancer cases and 5063 cancer-free controls. Genotyping was performed using MALDI-TOF mass spectrometry, and odds ratios were estimated using logistic regression.

RESULTS

Significant associations with breast cancer were confirmed for 7 of the 10 SNPs. Analysis of the joint effect of the original 10 as well as the statistically significant 7 SNPs (rs2981582, rs3803662, rs889312, rs13387042, rs13281615, rs3817198 and rs981782) found a highly significant trend for increasing breast cancer risk with increasing number of risk alleles (P-trend 5.6 × 10(-20) and 1.5 × 10(-25), respectively). Odds ratio for breast cancer of 1.84 (95% confidence interval (CI): 1.59-2.14; 10 SNPs) and 2.12 (95% CI: 1.80-2.50; 7 SNPs) was seen for the maximum vs the minimum number of risk alleles. Additionally, one of the examined SNPs (rs981782 in HCN1) had a protective effect that was significantly stronger in premenopausal women (P-value: 7.9 × 10(-4)).

CONCLUSION

The strongly increasing risk seen when combining many low-penetrant risk alleles supports the polygenic inheritance model of breast cancer.

Differences in outcome of young breast cancer patients according to BRCA1 mutation status

Abstract #1044

Introduction&#x2028; 5 to 10 % of all breast cancer and 25 % of early onset breast cancer are inheritable, which may be caused by mutations of tumour suppressor genes such as BRCA1. Moreover, the issue of a familial breast cancer has raised much attention in recent years due to numerous medical and social implications. In the present paper we investigate the clinical characteristic and outcomes of younger (&lt;50 years old) breast cancer patients with BRCA1 mutation in comparison to patients without this germline mutation.&#x2028; Methods and Materials&#x2028; This is an ongoing study and patients will be enrolled till end of 2008. Till now we followed 495 breast cancer patients who were diagnosed before age 50 and were asked to provide a blood sample for BRCA1 mutation screening. We compared contralateral breast cancer and ovarian cancer incidence, disease free, metastases free, and overall survival, between BRCA1 mutation carriers and non-carriers.&#x2028; Results&#x2028; BRCA1 mutations were detected in 90 breast cancer patients (5382insC in 60 patients, 300T/G in 18 pts, 185delAG in 10 pts, and 4153delAin 2 pts); the remaining 405 women did not carry the mutation. BRCA1 related tumours showed higher grade, higher Ki67 protein expression, more frequent negative oestrogen, progesterone, HER2-neu receptor status. Patients with BRCA1 mutation had a higher incidence of bilateral breast (40% compared to 10% in non mutated patients) and ovarian cancer (16% compared to less than 1% in non mutated patients. 10-years OS (overall survial) was 81% in no BRCA1 mutation patients compare to 88% in mutated BRCA1 patients (p=0.7), 10-years DSF (local-regional and distant failure) was 81% vs. 67% (p=0.8), 10-years MFS (metastases free survival) was 85% vs 71% (p=0.1), and 10-years RFS (recurrence free survival) was 90% vs. 80% (p=0.1) respectively.&#x2028; Multivariate Cox analysis for DFS showed that node ratio &gt; 12% (HR=2.12), increasing tumour diameter (HR=1.23), experienced significantly decreased DFS. Furthermore, overall survival analysis also showed that node ratio &gt; 12% (HR=2.65), increasing tumour diameter (HR=1.23), experienced significantly decreased OS. There is an insignificant trend for patients without BRCA1 mutation and younger to have worse DFS (HR=1.28) and worse OS (HR=2.23).&#x2028; Conclusions&#x2028; Patients with BRCA1 mutations have higher incidence of bilateral breast and ovarian cancer which imposes the need for frequent and careful follow-up after therapy. Node ratio and tumour diameter are the strongest prognostic factors. A final conclusion will require more patients and longer follow up.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 1044.

Central nervous system involvement in severe congenital neutropenia: neurological and neuropsychological abnormalities associated with specific HAX1 mutations

OBJECTIVES

Homozygous mutations in the HAX1 gene were recently identified in severe congenital neutropenia patients belonging to the original Kostmann family in northern Sweden. Our observations suggested that these patients also develop neurological and neuropsychological symptoms.

METHODS

Detailed clinical studies and mutation analyses were performed in the surviving patients belonging to the Kostmann kindred and in two patients not related to this family, along with studies of HAX1 splice variant expression in normal human tissues.

RESULTS

Five of six Kostmann family patients and one other patient from northern Sweden harboured homozygous HAX1 mutations (568C-->T, Q190X) and one carried a heterozygous ELA2 gene mutation. One Swedish patient of Kurdish extraction carried alternative homozygous HAX1 mutations (131G-->A, W44X). All the three patients with Q190X mutations who were alive and available for evaluation developed neurological disease with decreased cognitive function, and three of four patients who reached 10 years developed epilepsy. In contrast, the patients with the ELA2 and W44X HAX1 mutations, respectively, showed no obvious neurological abnormalities. Moreover, two alternative HAX1 splice variants were identified in normal human tissues, including the brain. Both transcripts contained exon 5, harbouring the Q190X mutation, whereas the 5' end of exon 2 containing the W44X mutation was spliced out from the second transcript.

CONCLUSIONS

We describe neurological and neuropsychological abnormalities for the first time in Kostmann disease patients. These central nervous system symptoms appear to be associated with specific HAX1 mutations.

Response to neo-adjuvant chemotherapy in women with BRCA1-positive breast cancers

PURPOSE

There have been no studies to date which look at the relative effectiveness of different regimens of chemotherapy in women who have breast cancer and who carry a BRCA1 germ-line mutation. We wished to compare rates of response to neo-adjuvant chemotherapy in BRCA1 mutation carriers and non-carrier controls.

EXPERIMENTAL DESIGN

From a registry of 3,479 patients, we identified 44 Polish women who carried a BRCA1 founder mutation and who had been treated with neo-adjuvant chemotherapy for breast cancer, and 41 age- and hospital-matched controls.

RESULTS

35 of the 44 BRCA1 mutation carriers (80%) experienced a partial or complete response to neo-adjuvant chemotherapy, compared to 39 of the 41 (95%) non-carriers (P=0.05). In the hereditary subgroup, response rates differed depending on whether or not a taxane (docetaxel) was given. Six of the 15 BRCA1 carrier women given docetaxel with doxorubicin responded (complete or partial), compared to 29 of 29 given other (DNA-damaging) therapies (P=0.001). Among the non-carriers, the rates of response to the two categories of chemotherapy were similar.

CONCLUSIONS

Breast cancers among BRCA1 carriers frequently do not exhibit sensitivity to docetaxel in the neo-adjuvant setting. It is likely that normal BRCA1 is required for clinical response to mitotic spindle poisons.

XPD Common Variants and their Association with Melanoma and Breast Cancer Risk

There are suggestions in the literature that common variants in the XPD gene may be associated with an altered risk of melanoma and breast cancer. To establish if the XPD common variants Asp312Asn and Lys751Gln are associated with an increased melanoma or breast cancer risk we performed an association study based on genotyping 426 unselected patients with malignant melanoma (MM) and 1830 consecutive breast cancer cases and compared the results to 1262 geographically matched newborns, 621 adults from the region of Szczecin (unselected for age and cancer family history), 421 healthy adults age- and sex-matched with the melanoma cases and 511 healthy controls matched with the breast cancer patients from the region of Szczecin. Additionally we examined the prevalence of three additional XPD variants, Gly156Gly, Leu485Pro and Arg112His amongst the 421 unselected melanoma patients. All of the variants when evaluated singularly were found not to be associated either with melanoma or breast cancer risk in younger or older patients. A modest association was observed with breast cancer risk when the Lys751Gln_CC/Asp312Asn_AA genotype (OR=1.5, p<0.05) segregated together. Individuals harboring the Lys751Gln_CC/Gly156Gly_CC genotype were significantly over-represented among late-onset melanoma cases (OR=1.7, p<0.05). The results of analyses of linkage disequilibrium and haplotype frequency support the thesis that a combination of at least two SNPs (Lys751Gln_CC/Gly156Gly_CC or Lys751Gln_CC/Asp312Asn_AA) inherited as a haplotype was associated with disease. These two pairs of SNPs could therefore be regarded as a single hereditary unit that would have a very small probability of being disrupted by recombination. Additional studies are required to determine whether these particular changes can be associated with an increased risk of other malignancies at different sites of origin.

BRCA1-positive breast cancers in young women from Poland

We identified 4316 unselected incident cases of early-onset breast cancers (<51 ears of age at diagnosis) in 18 Polish hospitals between 1996 and 2003. We were able to obtain a blood sample for DNA analysis from 3472 of these (80.4%). All cases were tested for the presence of three founder mutations in BRCA1. The proportion of cases with a BRCA1 mutation was 5.7%. The hereditary proportions were higher than this for women with breast cancer diagnosed before age 40 (9%), for women with cancer of medullary or atypical medullary histology (28%), for those with bilateral cancer (29%) or with a family history of breast or ovarian cancer (13%). It is reasonable to offer genetic testing to women with early-onset breast cancer in Poland.

Association of polymorphisms and haplotypes in the human growth hormone 1 (GH1) gene with breast cancer

The growth hormone 1 (GH1)/insulin-like growth factor I (IGF-I) axis plays an important role in the development of breast cancer. By binding to its receptor, GH1 stimulates the production of IGF-I and its binding protein IGFBP3, resulting in the regulation of cell proliferation, differentiation and apoptosis. The GH1 gene expression is regulated by a highly polymorphic proximal promoter and a distal locus control region (LCR) 14.5 kb upstream of the gene. We investigated the effect of single nucleotide polymorphisms (SNPs) in the LCR and in the promoter region and an intron 4 SNP (IVS4+90 T/A) on breast cancer risk in a large cohort of Polish and German familial breast cancer cases and controls. SNPs in the LCR did not show an influence on breast cancer risk, either alone or in haplotypes. Three SNPs in the promoter region (G-340T, A-68G/C and A-63T/C) showed an increased and four SNPs (A-137G, G-119T, G-93delG and T-4G) a decreased allele frequency in the cases compared with the controls. Two of the SNPs (A-137G and G-93delG) lead to a decreased breast cancer risk among the minor allele carriers in the joint analysis of the two populations (odds ratio (OR) 0.62, 95% confidence interval (95% CI) 0.44-0.89, P = 0.01 and OR 0.65, 95% CI 0.47-0.90, P = 0.01, respectively). Haplotype analysis with these seven promoter SNPs revealed a protective association (OR 0.61, 95% CI 0.37-1.00, P = 0.04) for the haplotype GAGdAAT, containing the G-93delG variant allele, which in the single analysis already showed a protective effect. The effect was marginally stronger in combination with the LCR GC haplotype (OR 0.49, 95% CI 0.23-1.01, P = 0.04).

A common variant of CDKN2A (p16) predisposes to breast cancer

BACKGROUND

A common missense variant of the CDKN2A gene (A148T) predisposes to malignant melanoma in Poland. An association between malignant melanoma and breast cancer has been reported in several families with CDKN2A mutations,

OBJECTIVE

To determine whether this variant also predisposes to breast cancer.

METHODS

Genotyping was undertaken in 4209 cases of breast cancer, unselected for family history, from 18 hospitals throughout Poland and in 3000 controls.

RESULTS

The odds ratio (OR) associated with the CDKN2A allele for women diagnosed with breast cancer before the age of 50 was 1.5 (p = 0.002) and after age 50 it was 1.3 (p = 0.2). The effect was particularly strong for patients diagnosed at or before the age of 30 (OR = 3.8; p = 0.0002).

CONCLUSIONS

CDKN2A appears to be a low penetrance breast cancer susceptibility gene in Poland. The association should be confirmed in other populations.

BRCA1 and BRCA2 mutations as prognostic factors in bilateral breast cancer patients

BACKGROUND

Incidence of primary bilateral breast cancer (BC) is rare and does not exceed 5%. BRCA1/2 mutation carriers diagnosed with breast cancer have a strong life time risk of developing contralateral breast cancer (53% versus 2%).

PATIENTS AND METHODS

A group of 108 patients with bilateral breast cancer, who reported at our Cancer Centres from 2000 to 2002, were subjected to genetic testing. Similarities and differences between BRCA1/2 carriers and non-carriers were analysed in terms of family history, pathology of tumour, age of diagnosis, developing contralateral BC and second primary cancer.

RESULTS

BRCA1/2 mutations were detected in 32 of 108 patients. Family history of BC was identified in 46.9% of these patients compared with 22.4% of non-carriers (P <0.05). Synchronous BC was diagnosed significantly rarer [4 of 32 (12.5%)] in BRCA1/2 carriers than in the non-carrier group [26 of 76 (34.2%)]. In addition, patients with BRCA mutations were younger when they were diagnosed than non-carriers. BRCA1/2 carriers had a significantly higher incidence of medullary BC (13.6% versus 1.7%) and developed ovarian cancer significantly more frequently than non-carriers (12 of 32 and 1 of 72 patients, respectively).

CONCLUSIONS

Patients with bilateral BC having BRCA mutations are significantly younger than non-carriers. They also have a significantly higher family history of BC and an increased risk of developing ovarian cancer. The differences in clinical aspects of BRCA carriers with bilateral BC should be considered in clinical management.

High frequency of recurrent mutations in BRCA1 and BRCA2 genes in Polish families with breast and ovarian cancer

Germ-line mutations in BRCA1 and BRCA2 genes result in a significantly increased risk of breast and ovarian cancer. Other genes involved in an increased predisposition to breast cancer include the TP53 gene, mutated in Li-Fraumeni syndrome. To estimate the frequency of germ-line mutations in these three genes in Upper Silesia, we have analyzed 47 breast/ovarian cancer families from that region. We found five different disease predisposing mutations in 17 (36%) families. Twelve families (25.5%) carried known BRCA1 mutations (5382insC and C61G), four families (8.5%) carried novel BRCA2 mutations (9631delC and 6886delGAAAA), and one family (2%) harbored novel mutation 1095del8 in the TP53 gene, which is the largest germline deletion in coding sequence of this gene identified thus far. The 5382insC mutation in BRCA1 was found in 11 families and the 9631delC mutation in BRCA2 occurred in three families. These two mutations taken together contribute to 82% of all mutations found in this study, and 30% of the families investigated harbor one of these mutations. The very high frequency of common mutations observed in these families can only be compared to that reported for Ashkenazi Jewish, Icelandic, and Russian high-risk families. This frequency, however, may not be representative for the entire Polish population. The observed distribution of mutations will favor routine pre-screening of predisposed families using a simple and cost-effective test.

The effect of the genetic polymorphisms of CYP1A1,CYP2D6, GSTM1 and GSTP1 on aromatic DNA adduct levels in the population of healthy women

Aromatic DNA adduct levels and polymorphisms of two phase I enzymes - CYP1A1 and CYP2D6 and two phase II enzymes - GSTM1 and GSTP1 were analyzed in a group of 133 nonsmoking healthy women 35-45 years old and holding jobs not connected with the exposure to the combustion products of organic matter. They were office workers from the south and north-eastern parts of Poland. Blood samples were collected in winter and in summer. Aromatic DNA adduct levels were measured in all winter and summer samples. The frequencies of CYP1A1, CYP2D6, GSTM1 and GSTP1 polymorphisms in samples from the studied women did not show any differences when compared with other Caucasian populations and the Polish male population studied previously. The differences in the levels of DNA adducts among the carriers of different genotypes were statistically non-significant. Analysis of combined genotypes selected the groups of volunteers with the highest and the lowest DNA adduct levels. The highest levels of DNA adducts were observed in the carriers of GSTM1(null)/CYP1A1Ile/Val (8.00+/-13.00 adducts/10(8) nucleotides in summer samples) and GSTP1-AA/CYP1A1Ile/Val genotypes (7.00+/-4.32 in winter and 7.30+/-7. 27/10(8) nucleotides in summer). The lowest levels of DNA adducts (3. 00+/-2.30 in winter and 2.00+/-3.16/10(8) nucleotides in summer) were found in the carriers of the genotype GSTP1-AG+GG/CYP1A1Ile/Val. The levels of DNA adducts in these groups were determined by the polymorphisms of GSTM1 and GSTP1 phase II detoxifying enzymes.

Founder mutations in the BRCA1 gene in Polish families with breast-ovarian cancer

We have undertaken a hospital-based study, to identify possible BRCA1 and BRCA2 founder mutations in the Polish population. The study group consisted of 66 Polish families with cancer who have at least three related females affected with breast or ovarian cancer and who had cancer diagnosed, in at least one of the three affected females, at age <50 years. A total of 26 families had both breast and ovarian cancers, 4 families had ovarian cancers only, and 36 families had breast cancers only. Genomic DNA was prepared from the peripheral blood leukocytes of at least one affected woman from each family. The entire coding region of BRCA1 and BRCA2 was screened for the presence of germline mutations, by use of SSCP followed by direct sequencing of observed variants. Mutations were found in 35 (53%) of the 66 families studied. All but one of the mutations were detected within the BRCA1 gene. BRCA1 abnormalities were identified in all four families with ovarian cancer only, in 67% of 27 families with both breast and ovarian cancer, and in 34% of 35 families with breast cancer only. The single family with a BRCA2 mutation had the breast-ovarian cancer syndrome. Seven distinct mutations were identified; five of these occurred in two or more families. In total, recurrent mutations were found in 33 (94%) of the 35 families with detected mutations. Three BRCA1 abnormalities-5382insC, C61G, and 4153delA-accounted for 51%, 20%, and 11% of the identified mutations, respectively.

Polymorphisms of the GSTP1 and GSTM1 genes and PAH-DNA adducts in human mononuclear white blood cells

Glutathione S-transferases (GSTs) are an important part of the protection system against a wide range of potentially harmful chemical compounds. GSTP1 and GSTM1 are mainly involved in detoxification reactions of PAH carcinogenic intermediates produced by cytochrome P450 (CYP). Polymorphism of the GST genes may influence the level of carcinogen-DNA adducts in human tissues and be associated with individual susceptibility to carcinogens. In this study, we examined the effect of common polymorphism in exon 5 (105Ile --> Val) of the GSTP1 gene, alone and in combination with GSTM1-deletion polymorphism, on the level of PAH-DNA adducts measured by (32)P-postlabeling assay in mononuclear white blood cells collected in winter and in summer from a total of 170 healthy volunteers. When GSTP1 genotypes alone were compared, no statistically significant differences in adduct levels were found. However, smokers with GSTM1(null)/GSTP1-AG or -GG combined genotype showed significantly higher adduct levels in summer than carriers of other GSTM1/GSTP1 combinations (5.60 +/- 5.10 vs. 3.45 +/- 4. 28/10(8) nucleotides, P = 0.015). Among smokers carrying GSTP1-AG or -GG genotype, individuals with GSTM1(null) genotype had a significantly higher level of adducts in summer than subjects with GSTM1(+) genotype (5.60 +/- 5.10 vs. 1.82 +/- 1.98/10(8), P = 0.002) and GSTM1(null)/GSTP1-AA genotype carriers (5.60 +/- 5.10 vs. 4.13 +/- 5.84/10(8), P = 0.03). When adduct levels measured either in winter or in the nonsmoker group were considered, no influence of GSTM1/GSTP1 genotypes was found. Our data show that the combined GSTM1 and GSTP1 genetic polymorphisms may modulate PAH-DNA adduct levels in mononuclear WBCs from individuals exposed to specific carcinogenic compounds, e.g., tobacco smoke, in relatively lower-exposure environmental conditions (i.e., in summer).

Modulation of DNA adduct levels in human mononuclear white blood cells and granulocytes by CYP1A1 CYP2D6 and GSTM1 genetic polymorphisms

The CYP1A1, CYP2D6 and GSTM1 genes encode biotransforming enzymes involved in activation and detoxification of xenobiotics. Metabolically activated chemical compounds may interact with DNA and form adducts. In this study, the effect of the GSTM1, CYP1A1 exon 7 and CYP2D6 polymorphisms on DNA adduct levels was studied in 170 healthy volunteers. DNA adducts levels were measured by 32P-postlabelling in mononuclear white blood cells (WBC, lymphocytes and monocytes) and granulocytes collected in summer and winter. The influence of the genotype on the level of DNA adducts in both types of WBCs was observed only in summer samples. Individuals with GSTM1 deficient (null) genotype had significantly elevated level of adducts in mononuclear WBCs (p = 0.045) and granulocytes (p = 0.031) compared to GSTM1 positives. Higher adduct levels in carriers of combined GSTM1(null)/CYP1A1-Ile/Val genotype were found in both types of WBCs when compared to GSTM1(+)/CYP1A1-Ile/Ile genotype carriers (p = 0.046 in granulocytes, p = 0.092 in mononuclear WBCs). CYP2D6 wild-type homozygotes (EMs) and heterozygotes (HEMs) were shown to have significantly higher mononuclear WBC DNA adduct levels than mutant homozygotes (PMs) (p = 0.037 and p = 0.014). When confounding factors associated with PAH exposure were taken into account a statistically significant effect of CYP1A1 exon 7 polymorphism on DNA adduct levels was found (p = 0.012 in mononuclear WBCs, p = 0.043 in granulocytes). In a subgroup of current smokers (n = 95) high DNA adduct levels in granulocytes were associated with GSTM1(null) genotype, and increased adduct levels in mononuclear WBCs correlated with CYP2D6 EM and HEM genotypes. In winter samples the association between the genotype and DNA adduct levels was not observed.

Benzo(a)pyrene-albumin adducts in humans exposed to polycyclic aromatic hydrocarbons in an industrial area of Poland

OBJECTIVES

The interaction of benzo(a)pyrene with serum albumin was measured in an attempt to identify the actual exposure and to evaluate albumin adduct measurements as biomarkers for exposure monitoring.

METHODS

Benzo(a)pyrene-diol-epoxide (BPDE)-albumin adducts were measured by competitive enzyme linked immunosorbent assay (ELISA) in plasma of coke oven plant workers from three plants and from people living in a highly industrialised area of Silesia in Poland. Due to the high air concentrations of polycyclic aromatic hydrocarbons (PAHs) in this area, a control group was selected from a rural non-industrialised area in Poland. Breathing zone air measurements of PAHs were collected from some of the participants.

RESULTS

Coke oven plant workers and non-occupationally exposed people had similar concentrations of albumin adducts whereas the rural controls were significantly lower (2.74 fmol adducts/microgram albumin (SEM 0.124)). The mean concentration of BPDE-albumin adduct in plasma of both the occupational and the environmental groups were significantly higher in the summer samples (4.34 fmol adducts/microgram albumin (SEM 0.335) and 4.55 fmol adducts/microgram albumin (SEM 0.296), respectively) than in the winter samples (3.06 fmol adducts/microgram albumin (SEM 0.187) and 3.04 fmol adducts/microgram albumin (SEM 0.184), respectively) even though the air measurements showed higher concentrations of PAHs in the winter. The statistical analysis did not show any effects of air exposures on concentrations of BPDE-albumin adduct.

CONCLUSIONS

A multiple regression analysis of the measured concentrations of BPDE-albumin adducts for all the groups, during both seasons, indicates that occupational exposures do not contribute significantly to the formation of adducts. In general, the concentrations of albumin adducts found vary within relatively small limits for the two seasons and between the various groups of participants. No extreme differences were found.

[Analysis of aromatic DNA adducts in inhabitants of Upper Silesia]

Aromatic DNA adducts levels were measured in white blood cells collected from three groups of volunteers: occupationally exposed group (cokery workers), environmentally exposed group (residents from Silesia), control group (inhabitants of Biała Podlaska) using ELISA and 32P-postlabelling methods. The highest level of DNA adducts was observed in occupationally exposed group, slightly lower in the environmentally exposed group and much lower in the control group. Seasonal variations in the adducts levels were found in total white blood cells and in lymphocytes showing that the levels of DNA adducts reflect the present exposure to genotoxic agents in the air. It was also shown using 32P-postlabelling with HPLC that not only adducts with polycyclic aromatic hydrocarbons were found in human DNA.

DNA adducts in environmental, occupational and life-style studies in human biomonitoring

The importance of DNA adducts in carcinogenesis had been discussed. The 32P-postlabelling method was developed as a quantitative technique to measure the level of different DNA adducts including adducts in human DNA. The elevated level of DNA adducts was found in white blood cells in persons exposed environmentally and occupationally to high concentrations of PAHs (polycyclic aromatic hydrocarbons) in the ambient air. Tobacco also generated higher level of DNA adducts both in lymphocytes and laryngeal tissues of smokers. Exposure to styrene has been of interest world-wide because of the very high exposure and persistence of adducts in DNA of lamination workers.

Probing the active-site residues in Saccharomyces cerevisiae ferrochelatase by directed mutagenesis. In vivo and in vitro analyses

Ferrochelatase is a mitochondrial inner membrane-bound enzyme that catalyzes the insertion of ferrous iron into protoporphyrin, the terminal step in protoheme biosynthesis. The functional/structural roles of 10 invariant amino acid residues were investigated by site-directed mutagenesis in the yeast Saccharomyces cerevisiae ferrochelatase. The mutant enzymes were expressed in a yeast strain lacking the ferrochelatase gene HEM15 and in Escherichia coli. The kinetic parameters of the mutant enzymes were determined for the enzymes associated with the yeast membranes and the enzymes in the bacterial soluble fraction. They were compared with the in vivo functioning of the mutant enzymes. The main conclusions are the following. Glu-314 is critical for catalysis, and we suggest that it is the base responsible for abstracting the N-pyrrole proton(s). His-235 is essential for metal binding. Asp-246 and Tyr-248 are also involved in metal binding in a synergistic manner. The Km for protoporphyrin was also increased in the H235L, D246A, and Y248L mutants, suggesting that the binding sites of the two substrates are not independent of each other. The R87A, Y95L, Q111E, Q273E, W282L, and F308A mutants had 1.2-2-fold increased Vm and 4-10-fold increased Km values for protoporphyrin, but the amount of heme made in vivo was 10-100% of the normal value. These mutations probably affected the geometry of the active center, resulting in improper positioning of protoporphyrin.

32P-postlabelling of bulky human DNA adducts enriched by different methods including immunoaffinity chromatography

DNA adducts in lymphocytes and granulocytes of men exposed occupationally and environmentally to high concentrations of aromatic compounds in air were measured by the 32P-postlabelling method. Adducts in the same samples were characterized using nuclease P1 enrichment, butanol extraction and immunoaffinity purification with an antiserum raised against benzo[alpha]pyrene diol epoxide (BPDE). Only part of the adducts found in human samples were extracted by butanol. It also seemed, that only a small part of them belonged to the group of polycyclic aromatic hydrocarbons (PAHs) recognised by the antibody. Relative content of hydrophobic adducts and those with a structure similar to PAHs was higher in winter samples (when exposure to aromatic chemicals in air was higher) in comparison to samples collected in summer.

Seasonal variation of DNA adduct pattern in human lymphocytes analyzed by 32P-HPLC

32P-HPLC is a recently published method to generate DNA adduct profiles after exposure to a complex of genotoxic substances. The low detection limit enables characterization of individual DNA adducts in the general population. The 32P-HPLC method was applied to human lymphocytes and granulocytes from Silesia, a polluted industrial region in the south of Poland. Human samples were collected at the end of winter and summer to investigate the seasonal influence on DNA adduct formation. In lymphocytes a strong seasonal variation was seen in total DNA adducts, with winter values exceeding the summer values by 7.33 +/- 3.56 times. Granulocytes did not show any seasonal variation. In winter-collected lymphocytes the DNA adduct levels were 21.4 +/- 16.6/10(8) normal nucleotides (NN) while the summer values were 2.96 +/- 2.46/10(8) NN. Granulocytes had 8.06 +/- 7.76 and 9.59 +/- 6.19 DNA adducts/10(8) NN during winter and summer respectively. The lymphocyte DNA adduct profile consisted of at least 16 individual or clusters of DNA adducts. All 16 had a clear winter influence, with a winter:summer ratio of 1.6-15.3, indicating exposure to a complex mixture of genotoxic substances. The DNA adducts analyzed in human lymphocytes had retention times similar to DNA adducts generated by polycyclic aromatic hydrocarbons. The suggested candidates for DNA adducts displayed a similar seasonal variation in airborne particles to that found in DNA adducts in lymphocytes of humans living in the area. This is the first application of the 32P-HPLC method to analysis of DNA adducts in human tissues.

Biological monitoring of polycyclic aromatic hydrocarbon exposure in a highly polluted area of Poland

Air pollution in Poland and particularly in Silesia is among the worst in Europe. Many coal mines and coke oven plants are located in this area, representing a major source of carcinogenic polycyclic aromatic hydrocarbons (PAHs). We quantitated the PAH exposure level in air samples using personal sampling devices, collected urine samples from the same individuals, and measured 1-hydroxypyrene with high performance liquid chromatography. Samples were collected twice, once in February and once in September. Mean PAH level of samples collected at three different coke oven plants varied from 2.3 micrograms/m3 to 12.3 micrograms/m3; the lowest mean was in September. Mean levels of 0.15 micrograms/m3 (September) and 0.44 micrograms/m3 (February) were noted for the environmentally exposed group. Mean urinary 1-hydroxypyrene varied from 2.45 to 13.48 mumol/mol creatinine at the three coke oven plants. The corresponding variation between the three different environmentally exposed groups in Silesia was 0.41-1.54 mumol/mol creatinine. In the nonindustrialized area, the mean varied from 0.20 to 0.14 mumol/mol creatinine. Seasonal variation was found both at the coke oven plants and in the environmental exposed groups in Silesia. Both PAH levels and 1-hydroxypyrene varied seasonally among coke oven workers and the environmentally exposed group. Our study shows that PAH exposure in the industrialized area of Silesia is high compared to levels in Western Europe. 1-Hydroxypyrene excretion in environmentally exposed individuals in Poland is among the highest in Europe.

Immunohistochemical quantitation of polycyclic aromatic hydrocarbon-DNA adducts in human lymphocytes

The formation of polycyclic aromatic hydrocarbon-DNA adducts was studied in peripheral blood lymphocytes obtained from men with occupational and environmental exposure. Subjects included coke factory workers, residents from the vicinity of the cokery, and rural region inhabitants (16 individuals in each exposure group). Adducts were determined by immunohistochemical analysis using a polyclonal antiserum recognizing benzo(a)pyrene and related polycyclic aromatic hydrocarbon diol epoxide-DNA adducts, a biotinylated secondary antiserum, and streptavidin-conjugated FITC. Propidium iodide was used to quantitate nuclear DNA. Dual fluorescence intensities were simultaneously measured with a Zeiss Axiovert microscope and a Bio-Rad MRC-600 argon laser scanning confocal attachment. Adducts were significantly elevated (P < 0.001) in both occupational and environmental groups, as compared to the rural control group by Mann-Whitney U test. The distribution of the data indicated the existence of cells with relatively higher adduct levels. The percentages of these so called "higher adduct-level cells" were 13.6, 11.5, and 3.7 in cokery workers, environmentally exposed individuals, and rural controls, respectively. The immunohistochemical method allows visualization and relative quantitation of polycyclic aromatic hydrocarbon-DNA adducts in individual lymphocytes. It requires a much smaller amount of blood than the previously used 32P-postlabeling and ELISA methods, which used isolated bulk DNA. It can also be used for adduct quantitation in biopsy material. The results of this pilot study indicate that this technique is a promising addition to biomonitoring studies.

The sequence of 12.5 kb from the right arm of chromosome II predicts a new N-terminal sequence for the IRA1 protein and reveals two new genes, one of which is a DEAD-box helicase

We have determined the complete nucleotide sequence of a 12.5 kb segment from the right arm of chromosome II carried by the cosmid alpha 20. The sequence encodes the 5' end of the IRA1 gene. Two complete new open reading frames and the 3' non-coding region of the SUP1 (SUP45) gene. A comparison of our sequence with the data bank reveals a 154 amino acid extension at the N-terminus of Ira1p compared to the previously predicted sequence. According to the 11th edition of the Saccharomyces cerevisiae genetic map, our sequence should encode the MAK5 gene, which is necessary for the maintenance of dsRNA killer plasmids. One of the two new open reading frames, YBR1119, is predicted to encode an RNA helicase, thus YBR1119 may correspond to the MAK5 gene.

An analysis of the sequence of part of the right arm of chromosome II of S. cerevisiae reveals new genes encoding an amino-acid permease and a carboxypeptidase

We have analysed two new genes, YBR1007 and YBR1015, discovered during the systematic sequencing of chromosome II of S. cerevisiae. YBR1007 shows strong similarities to amino-acid permeases, in particular the high-affinity proline permeases of S. cerevisiae and A. nidulans. The number and position of the predicted membrane-spanning domains suggest a conserved structure for these proteins, with 12 trans-membrane domains. YBR1015 shows strong similarities to serine carboxypeptidases; all three residues of the "catalytic triad" typical of this family of enzymes are conserved in the YBR1015 protein. In a preliminary functional analysis we have created a null allele of the YBR1015 gene, and shown that it is not essential for cellular viability.

The sequence of 29.7 kb from the right arm of chromosome II reveals 13 complete open reading frames, of which ten correspond to new genes

We have determined the complete nucleotide sequence of a 29.7 kb segment from the right arm of chromosome II carried by the cosmid alpha 61. The sequence encodes the 3' region of the IRA1 gene and 13 complete open reading frames, of which ten correspond to new genes and three (CIF1, ATPsv and CKS1) have been sequenced previously. The density of protein coding sequences is particularly high and corresponds to 84% of the total length. Two new genes encode membrane proteins, one of which is particularly large, 273 kDa. In one case (ATPsv), the comparison of our sequence and the published sequence reveals significant differences.

Seasonal variation of aromatic DNA adducts in human lymphocytes and granulocytes

DNA adducts were measured by 32P-postlabelling in lymphocytes and granulocytes of 75 healthy men exposed occupationally and environmentally to high concentrations of aromatic compounds in the ambient air. Volunteers enrolled in the study were men working at the coke batteries and nonoccupationally exposed inhabitants of Silesia, a highly industrialized region in southern Poland. Blood samples were drawn twice: in February and September 1992. Seasonal variations in the levels of DNA adducts were found only in lymphocytes: 3.6- and 8.7-fold in the occupationally and environmentally exposed groups respectively. In smokers the seasonal variation was as large as 12.8-fold in the environmentally exposed group. No seasonal variations were observed in granulocytes. The observed seasonal variation in the level of aromatic DNA adducts coincided with winter/summer differences in the concentrations of benzo[a]pyrene in the ambient air of Silesia. The study recommends the application of lymphocytes for adduct studies in chronic exposures and provides evidence on the repair of aromatic adducts in lymphocytes.

Seasonal variations in levels of DNA adducts and X-spots in human populations living in different parts of Poland

White blood cell DNA adducts were measured in coke oven workers, in residents from the area next to the coke oven in Silesia, Poland (highly industrialized region), and in residents from the rural area of Poland using the 32P-postlabeling technique. This method detected aromatic adducts including adducts formed by polycyclic aromatic hydrocarbons (PAHs). Highest levels of adducts in DNA were seen in the group of coke battery workers (6.9 adducts/10(8) nucleotides). Seasonal variations in levels of DNA adducts were observed both in residents of the district near the coke oven area and individuals from the rural area of Poland. Blood samples collected from people living near the coke oven in winter showed much higher levels of DNA adducts than blood samples obtained in summer (5.0 adducts/10(8) nucleotides in winter and 1.4 adducts/10(8) nucleotides in summer). The difference in the level of DNA adducts between winter and summer was smaller in the group of people living in the rural area (3.2 adducts/10(8) and 2.2 adducts/10(8), respectively). In most cases the levels of X-spots correlated with the levels of other DNA adducts. Correlation coefficients(r) between the levels of X-spots and other adducts ranged between 0.46 and 0.74 (p < 0.05), except for coke oven workers where no correlation was observed.

Mutagenic and clastogenic activity of the chloro-nitroimidazole radiosensitizer P40 in vitro and in vivo

The hypoxic radiosensitizer 1-(2-hydroxy-3-methoxypropyl)-2-chloro-4-nitroimidazole [P40] was investigated for its mutagenic activity in bacterial Ames test as well as for genotoxic activity in micronucleus assay in vivo. This nitroimidazole showed the weak mutagenicity towards TA100 strain (base pair substitution) and towards TA98 strain (frameshift) only in the highest concentration. P40 induced also a significant increase in the frequency of micronucleated polychromatic erythrocytes (PCEs) at the doses of 0.6 mg/g and 1.2 mg/g. The maximum time response was at 48 h. The decrease of percentage of PCEs suggested the possible cytotoxicity on bone marrow cells after treatment with P40. Positive results in this battery short-term tests provide evidence of clastogenic activity of P40.

Aromatic DNA adducts in white blood cells of coke workers

White blood cell DNA adducts were measured in coke workers, local controls and countryside controls using the 32P-postlabelling technique. The method detected aromatic adducts including those formed by polycyclic aromatic hydrocarbons (PAHs). Coke workers are heavily exposed to PAHs particularly when working at the batteries. A difference in adduct levels was noted between the coke workers at the battery as compared to other jobs. The adduct levels in the non-battery were higher than those in the countryside controls.

Lack of genotoxic activity of metronidazole and P1 derivative in two eukaryotic tests

Metronidazole [1-(2-hydroxyethyl)-2-methyl-5-nitroimidazole] and P1 derivative [1-(2-hydroxy-3-methoxypropyl)-2-methyl-4-nitroimidazole] were investigated for their genotoxic activity in two eukaryotic tests: mitotic recombination in yeast and micronucleus test in mice. Both compounds showed no genotoxicity in these eukaryotic assays contrary to their well-documented mutagenic activity in microbial short-term tests.