Value of bilateral breast cancer for identification of rare recessive at-risk alleles: evidence for the role of homozygous GEN1 c.2515_2519delAAGTT mutation.

Virtually all known tumor predisposing genes have been identified via the analysis of familial cancer cases. Here we argue that this approach is likely to miss recessively acting cancer genes and suggest the analysis of family history-negative patients with multiple primary malignancies for identifying homozygous at-risk genotypes. We performed calculations showing that the homozygous carriers of rare recessive cancer predisposing alleles are unlikely to report a family history of the disease. We further revealed that the c.2515_2519delAAGTT homozygous mutation in a Holliday junction resolvase, GEN1, was overrepresented in women with bilateral breast cancer (BC) as compared to healthy controls [11/360 (3.1 %) vs. 18/1305 (1.4 %); odds ratio (OR) = 2.25 (1.02-4.75); p = 0.031], although this trend was not maintained in unilateral BC patients [23/1851 (1.2 %)]. Noticeably, presence of biallelic c.2515_2519delAAGTT mutation was associated with the absence of BC in mother both in bilateral and unilateral BC cases [7/239 (3.0 %) vs. 0/41 (0 %) and 21/1,558 (1.3 %) vs. 0/215 (0 %), respectively; Mantel-Haenszel p = 0.041]. Thus, this study suggests that identification of dominant and recessive cancer predisposing genes may require distinct study groups.

High prevalence and breast cancer predisposing role of the BLM c.1642 C>T (Q548X) mutation in Russia.

The BLM gene belongs to the RecQ helicase family and has been implicated in the maintenance of genomic stability. Its homozygous germline inactivation causes Bloom syndrome, a severe genetic disorder characterized by growth retardation, impaired fertility and highly elevated cancer risk. We hypothesized that BLM is a candidate gene for breast cancer (BC) predisposition. Sequencing of its entire coding region in 95 genetically enriched Russian BC patients identified two heterozygous carriers of the c.1642 C>T (Q548X) mutation. The extended study revealed this allele in 17/1,498 (1.1%) BC cases vs. 2/1,093 (0.2%) healthy women (p = 0.004). There was a suggestion that BLM mutations were more common in patients reporting first-degree family history of BC (6/251 (2.4%) vs. 11/1,247 (0.9%), p = 0.05), early-onset cases (12/762 (1.6%) vs. 5/736 (0.7%), p = 0.14) and women with bilateral appearance of the disease (2/122 (1.6%) vs. 15/1376 (1.1%), p = 0.64). None of the BLM-associated BC exhibited somatic loss of heterozygosity at the BLM gene locus. This study demonstrates that BLM Q548X allele is recurrent in Slavic subjects and may be associated with BC risk.

High level of miR-21, miR-10b, and miR-31 expression in bilateral vs. unilateral breast carcinomas.

We analyzed the expression of several microRNAs (miRs) implicated in breast cancer (BC) pathogenesis (miR-21, miR-10b, miR17-5p, mir-31, miR-155, miR-200c, miR-18a, miR-205, and miR-27a) in 80 breast carcinomas obtained from patients with bilateral BC (biBC) and 40 cases of unilateral BC (uBC). Unexpectedly, three miRs (miR-21, miR-10b and miR-31) demonstrated significantly higher level of expression in biBC vs. uBC (P = 0.0001, 0.00004 and 0.0002, respectively). Increased contents of miR-21, miR-10b and miR-31 were observed in all categories of biBC tumors, i.e., in synchronous biBC as well as in first and second tumors from metachronous biBC cases. Synchronous biBC showed more similarity of miR expression profiles within pairs that the metachronous doublets (P = 0.004). This study suggests that bilateral breast tumors have somewhat distinct pattern of molecular events as compared to the unilateral disease.

Distribution of coding apoptotic gene polymorphisms in women with extreme phenotypes of breast cancer predisposition and tolerance.

AIMS AND BACKGROUND: Comparison of subjects with extreme phenotypes of cancer susceptibility and tolerance allows to detect low-penetrance gene-disease interactions with a relatively small study size. METHODS AND STUDY DESIGN: We analyzed the distribution of 19 coding apoptotic gene polymorphisms (Bid Gly10Ser; Casp2 Leu141Val; Casp5 Ala90Thr and Val318Leu; Casp7 Glu255Asp; Casp8 His302Asp; Casp9 Val28Ala, His173Arg and Arg221Gln; Casp10 Ile479Leu; Faim Thr117Ala and Ser127Leu; DR4 Arg141His, Thr209Arg, Ala228Glu and Lys441Arg; Survivin Lys129Glu; TNFR1 Gln121Arg; XIAP Pro423Gln) in 121 breast cancer patients with clinical features of a hereditary predisposition (family history and/or early onset and/or bilaterality) and 142 elderly tumor-free women. RESULTS: None of the individual single nucleotide polymorphisms (SNPs) demonstrated an association with breast cancer risk. The analysis of gene interactions revealed that the combination of XIAP Pro423Gln (rs5956583) AA genotype with Casp7 Glu255Asp (rs2227310) CG genotype appeared to prevail in "supercases" relative to "supercontrols" (25/121 [21%] vs 11/142 [8%], P = 0.002). We attempted to validate this association in the second round of case-control analysis, which involved 519 randomly selected breast cancer patients and 509 age-matched healthy women, but no difference was detected upon this comparison. CONCLUSIONS: Coding apoptotic gene polymorphisms do not play a major role in BC predisposition. The results of this investigation may be considered while designing future studies on breast cancer-associated candidate SNPs.

Evidence for depletion of CASP5 Ala90Thr heterozygous genotype in aged subjects.

Our previous studies, which included genotyping of multiple coding apoptotic gene polymorphisms, unexpectedly demonstrated a depletion of heterozygous CASP5 Ala90Thr (rs507879, c.268 G>A) genotypes in elderly subjects. Present investigation was aimed to validate this trend. An analysis of 510 subjects aged 75-103years revealed 205 (40%) CASP5 Ala90Thr heterozygotes as compared to 254 (50%) expected from the minor allele frequency 0.470 (p=0.000014). This deviation was not observed in 549 middle-aged (18-50years) controls (270 (49%) heterozygotes observed vs. 274 (50%) expected; minor allele frequency 0.475; p=0.743). Unfavorable significance of CASP5 heterozygous genotype may be explained by the role of the caspase-5 in inflammation-related processes. Almost all prior gene-longevity association studies focused on discrimination between "good" and "bad" gene variants. Here we present a distinct situation, where the combination of alternative alleles (i.e., heterozygosity) appears to be unfavorable as compared to the homozygous carriership of either gene variant.

High efficacy of first-line gefitinib in non-Asian patients with EGFR-mutated lung adenocarcinoma.

BACKGROUND: Several Asian studies demonstrated feasibility of front-line administration of gefitinib for the treatment of non-small cell lung carcinomas (NSCLCs) harboring intragenic epidermal growth factor receptor (EGFR) mutations. The experience of the use of this EGFR tyrosine kinase inhibitor (TKI) in non-Asian subjects remains limited. PATIENTS AND METHODS: The study included lung adenocarcinoma (AC) patients treated at the N.N. Petrov Institute of Oncology (Russia). RESULTS: DNA analysis of 192 consecutive AC revealed 38 (20%) TKI-sensitizing mutations. Presence of the exon 19 deletion (del19) or L858R was strongly correlated with nonsmoking status (smokers: 8/98 (8%); non-smokers: 30/94 (32%); p = 0.00004). The efficacy of first-line gefitinib therapy was evaluated in 25 patients with EGFR-mutated advanced AC. Twelve (48%) cases demonstrated tumor response (1 (4%) complete response, 11 (44%) partial responses; 10/17 (59%) patients with del19 mutation vs. 2/8 (25%) cases with L858R substitution, p = 0.11). The remaining 13 (52%) patients experienced disease stabilization. Median progression-free survival was 8.0 months. Grade 3 toxicity was the maximal adverse event, being observed only in 4 (16%) cases. CONCLUSION: Gefitinib may be considered as an upfront treatment option for EGFR-mutated NSCLC.

Large family with both parents affected by distinct BRCA1 mutations: implications for genetic testing.

Although the probability of both parents being affected by BRCA1 mutations is not negligible, such families have not been systematically described in the literature. Here we present a large breast-ovarian cancer family, where 3 sisters and 1 half-sister inherited maternal BRCA1 5382insC mutation while the remaining 2 sisters carried paternal BRCA1 1629delC allele. No BRCA1 homozygous mutations has been detected, that is consistent with the data on lethality of BRCA1 knockout mice. This report exemplifies that the identification of a single cancer-predisposing mutation within the index patient may not be sufficient in some circumstances. Ideally, all family members affected by breast or ovarian tumor disease have to be subjected to the DNA testing, and failure to detect the mutation in any of them calls for the search of the second cancer-associated allele.

Coding polymorphisms in Casp5, Casp8 and DR4 genes may play a role in predisposition to lung cancer.

Apoptosis plays a role in the elimination of DNA-damaged cells thus protecting the host from cancer development. Some data indicate that normal variations within the sequence of apoptotic genes may lead to suboptimal apoptotic capacity and therefore increased cancer risk. We tested 19 coding apoptotic gene SNPs in 2-stage molecular epidemiological study. For the preliminary sorting of SNP candidates, we employed a "comparison of extremes" approach, where 111 patients with highly pronounced LC susceptibility (non-smokers or young-onset light smokers) were analyzed against 110 subjects with the evidence for LC tolerance (elderly tumor-free heavy smokers). Three genotypes demonstrated possible association with LC risk (Leu/Leu-homozygotes for Casp5 Val318Leu versus other genotypes: OR=2.47 (95% CI: 1.07-5.69), p=0.03; His-carriers for Casp8 His302Asp: OR=2.26 (95% CI: 1.18-4.31), p=0.02; Arg-carriers for DR4 Lys441Arg: OR=1.89 (95% CI: 1.05-3.40), p=0.03), and therefore were selected for the validation. The extended study included 2 case-control series, namely subjects from Russia (351 LC cases and 538 controls) and Moldova (296 LC cases and 295 controls). Interestingly, all three candidate genotypes consistently demonstrated OR above 1 both in Russian and in Moldovian groups. Although the combined Mantel-Haenszel analysis yet failed to reach statistical significance (OR=1.22 (95% CI: 0.90-1.65), p=0.21; OR=1.17 (95% CI: 0.92-1.50), p=0.21; OR=1.19 (95% CI: 0.95-1.51), p=0.14, respectively), the obtained data indicate that Casp5, Casp8 and DR4 gene polymorphisms may deserve consideration in large-scale case-control studies of LC risk modifiers.