On the mutagenic action of adenine

The deamination of cytosine and adenine is mutagenic; the deamination of guanine is not. The deamination of cytosine leads to G = C → A = T point mutation and to G → A and C → T transition in the DNA molecule; the deamination of adenine leads to the opposite A → G and T → C transition. It is shown that adenine lack could be as mutagenic as adenine deamination and it is also shown schematically that adenine lack through defective adenine synthesis could give rise to a population of genetically abnormal cells incapable of any degree of differentiation, a state perhaps reminiscent of the most acute of leukaemias and the most anaplastic of cancers.     

Breast cancer risk associated with AURKA 91T -->A polymorphism in relation to BRCA mutations

In this study 759 breast cancer patients, including 9 BRCA1 and 98 BRCA2 mutation carriers, and 653 mutation-negative unaffected controls were genotyped for the AURKA 91T → A polymorphism. Individuals homozygous for the 91A allele were found to be at increased risk of breast cancer compared to 91T homozygotes (OR = 1.87; 95% CI = 1.09–3.21). This association was strengthened when cases carrying BRCA mutations were excluded (OR = 2.00; 95% CI = 1.15–3.47). BRCA carrier cases differed from sporadic cases and their allele distribution was very similar to controls. These results show a statistically significant increased risk of sporadic breast cancer for individuals that are homozygous for the 91A allele but no effect in carriers of BRCA mutations. This may throw light on previously conflicting results.     

Mutation analysis of <Emphasis Type="Italic">PALB2</Emphasis> in <Emphasis Type="Italic">BRCA1</Emphasis> and <Emphasis Type="Italic">BRCA2</Emphasis>-negative breast and/or ovarian cancer families from Eastern Ontario,Canada

Background

PALB2 has emerged as a breast cancer susceptibility gene. Mutations in PALB2 have been identified in almost all breast cancer populations studied to date, but the rarity of these mutations and lack of information regarding their penetrance makes genetic counseling for these families challenging. We studied BRCA1/2 -negative breast and/or ovarian cancer families to a) assess the contribution of PALB2 mutations in this series and b) identify clinical, pathological and family history characteristics that might make PALB2 screening more efficient.

Methods

The coding region of the PALB2 gene was analyzed in 175 probands with family histories of breast and/or ovarian cancer ascertained from a single Canadian institution in Eastern Ontario.

Results

We identified 2 probands with PALB2 mutations that are known or strongly considered to be pathogenic and 3 probands with missense mutations that are possibly pathogenic. One of the identified truncating mutations [c.3113G > A (p.Gly1000_Trp1038del – major product)], has been previously described while the other four mutations [c.3507_3508delTC (p.H1170Ffs*19), c.1846G > C (p.D616H), c.3418 T > G (p.W1140G), c.3287A > G (p.N1096S)] have not been previously reported. Loss of heterozygosity was detected in two breast tumors from one c.3507_3508delTC mutation carrier but not in other available tumors from that family or in tumors from carriers of other mutations.

Conclusions

PALB2 mutation screening identifies a small, but significant number of mutations in BRCA1/2 -negative breast and/or ovarian cancer families. We show that mutations are more likely to be found in families with three or more breast cancers as well as other BRCA2-related cancers. In our cohort, both clearly pathogenic mutations were identified in premenopausal breast cancer cases (2/77, 2.6%). Testing should be preferentially offered to affected women from such families.     

Contribution of BRCA1 germ-line mutations to breast cancer in Greece: a hospital-based study of 987 unselected breast cancer cases

Background:

In most Western populations, 5–10% of all breast cancer cases can be attributed to major genetic factors such as predisposing mutations in BRCA1 and BRCA2, with early-onset cases generally considered as an indicator of genetic susceptibility. Specific BRCA1 and BRCA2 mutations or different mutation frequencies have been identified in specific populations and ethnic groups. Previous studies in Greek breast and/or ovarian cancer patients with family history have shown that four specific BRCA1 mutations, c.5266dupC, G1738R, and two large genomic rearrangements involving deletions of exons 20 and 24, have a prominent function in the population''s BRCA1 and BRCA2 mutation spectrum.

Methods:

To estimate the frequency of the above mutations in unselected Greek breast cancer women, we screened 987 unselected cases independently of their family history, collected from major Greek hospitals.RESULTS: Of the 987 patients, 26 (2.6%) were found to carry one of the above mutations in the BRCA1 gene: 13 carried the c.5266dupC mutation (1.3%), 6 carried the exon 24 deletion (0.6%), 3 carried the exon 20 deletion (0.3%), and 4 carried the G1738R mutation (0.4%). Among 140 patients with early-onset breast cancer (<40 years), 14 carried one of the four mutations (10.0%).

Conclusion:

These results suggest that a low-cost genetic screening for only the four prominent BRCA1 mutations may be advisable to all early-onset breast cancer patients of Greek origin.     

Molecular mechanism of base pairing infidelity during DNA duplication upon one-electron oxidation

The guanine radical cation (G^•+) is formed by one-electron oxidation from its parent guanine (G). G^•+ is rapidly deprotonated in the aqueous phase resulting in the formation of the neutral guanine radical [G(-H)^•]. The loss of proton occurs at the N1 nitrogen, which is involved in the classical Watson-Crick base pairing with cytosine (C). Employing the density functional theory (DFT), it has been observed that a new shifted base pairing configuration is formed between G(-H)^• and C constituting only two hydrogen bonds after deprotonation occurs. Using the DFT method, G(-H)^• was paired with thymine (T), adenine (A) and G revealing substantial binding energies comparable to those of classical G-C and A-T base pairs. Hence, G(-H)^• does not display any particular specificity for C compared to the other bases. Taking into account the long lifetime of the G(-H)^• radical in the DNA helix (5 s) and the rapid duplication rate of DNA during mitosis/meiosis (5-500 bases per s), G(-H)^• can pair promiscuously leading to errors in the duplication process. This scenario constitutes a new mechanism which explains how one-electron oxidation of the DNA double helix can lead to mutations.     

4-Fluoro-N-butylphenylacetamide: a synthetic phenylacetate derivative that upregulates Bcl-X(S), activates caspase cascade and induces apoptosis in human squamous lung cancer CH27 cells

The CDKN2A locus on human chromosome 9p21 encodes two proteins, p16 and p14ARF, that mainly regulate cell cycle progression and cell survival via the pRb and p53 pathways, respectively. Germline mutations in CDKN2A have been linked to development of cutaneous melanoma in some families with hereditary melanoma. Due to overlapping open reading frames in exon 2, some mutations in this exon affect both p16 and p14ARF. We previously reported a 24 bp deletion in CDKN2A exon 2 in a patient with multiple primary melanomas and melanoma heredity. To further clarify the possible role of the 24 bp deletion for melanoma development, especially with respect to p14ARF, we have studied the cellular distribution and function of the resulting p14ARF del (77–84) and p16 del (62–69) mutant proteins. We found that p14ARF del (77–84) had decreased nucleolar localization, and was less efficient than wt p14ARF in stabilizing p53, inducing G1 cell cycle arrest, and inhibiting colony formation. The p16 del (62–69) mutant localized predominantly to the cytoplasm, did not induce G1 cell cycle arrest, and failed to suppress colony formation. We conclude that p14ARF del (77–84) has retained the ability to stabilize MDM2 and p53, but that it is less potent than wt p14ARF. This partial functional defect may complement the clearly defective p16 del (62–69) mutant and thus contribute to melanoma development in patients carrying the 24 bp deletion in CDKN2A.     

A morphometric analysis of glomerular and tubular alterations following fast-neutron irradiation of the pig and monkey kidney

Purpose: The morphologic responses of the pig and monkey kidney to fractionated fast-neutron irradiation were assessed.

Methods and Materials: The right kidney of approximately 14-week-old female Large White pigs was irradiated with 6.6–12.2 Gy of fast neutrons (42 MeV_d→Be) given as 12 fractions over 18 days; the left kidney served as the contralateral unirradiated kidney. Both kidneys were removed at necropsy 2 years postirradiation. In addition, the remaining hypertrophied kidney of four unilaterally nephrectomized adult rhesus monkeys was irradiated with a total dose of 11.0 Gy fast neutrons (45 MeV_p→Be) given in an identical fractionation regimen to that used in the pig studies. These kidneys were removed when the animals exhibited renal failure, between 32–94 weeks postirradiation. Glomeruli were assessed for the presence of pathologic features, including intercapillary eosinophilic material (ICE), ectatic capillaries, thrombi, hemorrhage, and sclerosis. The relative proportion of renal cortex occupied by glomeruli, interstitium, normal, or abnormal tubules was determined using a Chalkley point grid.

Results: The incidence of normal glomeruli, ectatic capillaries, thrombosis, and periglomerular fibrosis were significantly different in the irradiated pig kidneys compared with the unirradiated contralateral kidneys (p ≤ 0.02). Linear regression analysis demonstrated a significant dose relationship in terms of normal glomeruli, ectatic capillaries, and ICE (r ≥ 0.64; p ≤ 0.04). Irradiation was also associated with a significant (p < 0.0001) decrease and increase in the volume of renal cortex occupied by normal and abnormal tubules, respectively. Similar morphometric changes were noted in the irradiated monkey kidneys.

Conclusions: The morphologic changes seen in the pig and monkey kidney after fractionated irradiation with fast neutrons are similar to those previously noted after single-dose or fractionated-photon irradiation. These findings support the hypothesis that the development of radiation nephropathy in these various models involves common pathophysiological mechanisms.     

Clinical Benefit of Tyrosine Kinase Inhibitors in Advanced Lung Cancer with EGFR-G719A and Other Uncommon EGFR Mutations

The optimal management of advanced non‐small cell lung cancer (NSCLC) with noncanonical epidermal growth factor receptor (EGFR) mutations (i.e., exon 19 deletion and exon 21 L858R) is constrained by the heterogeneous behavior of individual uncommon mutations and limited prospective clinical data in this setting. Despite encouraging results with osimertinib from a recently published phase II trial from South Korea, afatinib remains the only currently approved drug for patients with tumors harboring uncommon EGFR mutations (i.e., S768I, L861Q, and/or G719X). When used at the standard dose of 40 mg daily, afatinib is associated with significant rates of treatment‐related adverse events, leading to frequent dose reductions and treatment discontinuations. We report a case of a woman with advanced NSCLC harboring EGFR‐G719A mutation treated with afatinib (at an off‐label pulse dose strategy that merits further evaluation in prospective studies) with sustained partial response for 20 months with manageable expected toxicities. Subsequent disease progression was mediated by off‐target pan‐EGFR inhibitor (including osimertinib)–resistant KRAS mutation and not by acquisition of EGFR‐T790M. We further present the current state of evidence in the literature behind use of first‐, second‐, and third‐generation tyrosine kinase inhibitors and summarize the evolving spectrum of activity ascribed to osimertinib (and newer EGFR inhibitors with a more favorable therapeutic window and intracranial penetration) in this population of patients with advanced NSCLC and uncommon EGFR mutations.Key Points

• Uncommon EGFR mutations characterize a heterogeneous group of patients with advanced non‐small cell lung cancer (NSCLC).
• Afatinib is the only currently U.S. Food and Drug Administration–approved drug for management of advanced NSCLC with uncommon EGFR mutations (S768I, L861Q, and/or G719X).
• Afatinib treatment at 40 mg daily is associated with high rates of adverse events and dose reductions; alternative strategies including pulse intermittent dosing should be evaluated prospectively.
• Osimertinib (with favorable safety profile and intracranial penetration) has shown promising results in this population in a phase II trial from South Korea; additional trials are ongoing.

     

Genetic screening analysis of patients with hereditary diffuse gastric cancer from northern and northeastern Brazil

Background

Hereditary diffuse gastric cancer (HDGC) is a hereditary autosomal inherited syndrome associated with CDH1 germline mutations. In Brazil, gastrointestinal tumors are among the most prevalent tumor types and constitute a serious public health problem, especially in the northern and northeastern regions. This study aimed to investigate germline mutations, methylation pattern and genomic rearrangements in the CDH1 gene and quantitative changes in the DNA of HDGC patients in northern and northeastern Brazil.

Methods

Twenty-seven DNA samples from the members of four families affected by HDGC were analyzed using array comparative genomic hybridization (aCGH), DNA sequencing and methylation pattern.

Results

No evidence of gain and loss events or any rearrangements were found in any of the samples tested using aCGH. No promoter region hypermethylation was observed either. Two of the four families presented different types of germline mutations. The 185G > T and 1018A > G germline mutations detected in this study have been described in Asian and European families, respectively. The ancestors of the two families carrying these mutations had originated from those continents.

Conclusion

This is the first study to evaluate CDH1 gene germline mutations in Brazilian families with HDGC. In our study, 50% of the families showed no CDH1 gene alterations, and it is possible that in regions with a high incidence of gastric cancer, such as northern and northeastern Brazil, environmental factors might have induced the different genetic alterations analyzed in this study.     

A PALB2 mutation associated with high risk of breast cancer

Introduction

As a group, women who carry germline mutations in partner and localizer of breast cancer 2 susceptibility protein (PALB2) are at increased risk of breast cancer. Little is known about by how much or whether risk differs by mutation or family history, owing to the paucity of studies of cases unselected for family history.

Methods

We screened 1,403 case probands for PALB2 mutations in a population-based study of Australian women with invasive breast cancer stratified by age at onset. The age-specific risk of breast cancer was estimated from the cancer histories of first- and second-degree relatives of mutation-carrying probands using a modified segregation analysis that included a polygenic modifier and was conditioned on the carrier case proband. Further screening for PALB2 c.3113G > A (W1038X) was conducted for 779 families with multiple cases of breast cancer ascertained through family cancer clinics in Australia and New Zealand and 764 population-based controls.

Results

We found five independent case probands in the population-based sample with the protein-truncating mutation PALB2 c.3113G > A (W1038X); 2 of 695 were diagnosed before age 40 years and 3 of 708 were diagnosed when between ages 40 and 59 years. Both of the two early-onset carrier case probands had very strong family histories of breast cancer. Further testing found that the mutation segregated with breast cancer in these families. No c.3113G > A (W1038X) carriers were found in 764 population-based unaffected controls. The hazard ratio was estimated to be 30.1 (95% confidence interval (CI), 7.5 to 120; P < 0.0001), and the corresponding cumulative risk estimates were 49% (95% CI, 15 to 93) to age 50 and 91% (95% CI, 44 to 100) to age 70. We found another eight families carrying this mutation in 779 families with multiple cases of breast cancer ascertained through family cancer clinics.

Conclusions

The PALB2 c.3113G > A mutation appears to be associated with substantial risks of breast cancer that are of clinical relevance.     

A phase II trial of gefitinib as first-line therapy for advanced non-small cell lung cancer with epidermal growth factor receptor mutations

Retrospective analysis has shown that activating mutations in exons 18–21 of the epidermal growth factor receptor (EGFR) gene are a predictor of response to gefitinib. We conducted a phase II trial to evaluate the efficacy and safety of gefitinib as first-line therapy for advanced non-small cell lung cancer (NSCLC) with EGFR mutations. Patients with stage IIIB or IV chemotherapy-naïve NSCLC with EGFR mutation were treated with 250 mg gefitinib daily. For mutational analysis, DNA was extracted from paraffin-embedded tissues and EGFR mutations were analysed by direct sequence of PCR products. Twenty (24%) of the 82 patients analysed had EGFR mutations (deletions in or near E746-A750, n=16; L858R, n=4). Sixteen patients were enrolled and treated with gefitinib. Twelve patients had objective response and response rate was 75% (95% CI, 48–93%). After a median follow-up of 12.7 months (range, 3.1–16.8 months), 10 patients demonstrated disease progression, with median progression-free survival of 8.9 months (95% CI, 6.7–11.1 months). The median overall survival time has not yet been reached. Most of the toxicities were mild. This study showed that gefitinib is very active and well tolerated as first-line therapy for advanced NSCLC with EGFR mutations.     

G → A mutation of ras genes and infrequent p53 gene mutation in rat transplantable thyroid carcinoma lines from tumors induced in vivo by N-bis(2-hydroxypropyl)nitrosamine

In a comparative study, we have investigated mutational activation of three kinds of ras genes and the p53 gene (exons 5–8) in 19 rat transplantable thyroid carcinoma lines derived from in vivo tumors induced by DHPN. Mutations were identified using single-strand conformation polymorphism and DNA sequencing analysis, and activated ras oncogenes were detected in 6 lines (31%). These all had mutations in Ki-ras codons at 12 or 63, and one of them also possessed a Ha-ras mutation at codon 12 as a double mutation. Three mutations of Ki-ras at codon 12 involved the second nucleotide and two the first position, the other being found at the first nucleotide in codon 63. Base alterations of p53 gene were found in two lines. One had an insertion of 1 base (thymine) between codon 206 and codon 207. Histologically, it was diagnosed as a poorly differentiated papillary carcinoma (scirrhous pattern). In the another case, there was no amino acid change although one base substitution occurred at codon 283 (GAG → GAA) of exon 8. These results indicate that, in the ras family, DHPN induces Ki-ras gene activation preferentially and that p53 mutation may be infrequent in thyroid carcinogenesis in rats, our data thus corresponding well with the previous reports that an inactivated p53 gene only plays a major role in human undifferentiated thyroid carcinomas.     

A risk of breast cancer in women - carriers of constitutional <Emphasis Type="Italic">CHEK2</Emphasis> gene mutations,originating from the North - Central Poland

Background

Germline mutations of the CHEK2 gene have been reported to be associated with breast cancer. In this study, we analyzed the association of CHEK2 mutations with the risk of development of breast cancer in women of North-Central Poland.

Methods

420 women with breast cancer and 435 controls were tested for three protein truncating (IVS2 + 1G > A, 1100delC, del5395) and one missense (I157T) CHEK2 mutation. IVS2 + 1G > A and I157T mutations were identified by RFLP-PCR, 1100delC variant was analyzed using an ASO-PCR and del5395 mutation by multiplex-PCR. The statistical tests: the odds ratio (OR) and Fisher’s exact test were used.

Results

In 33 out of 420 (7.9%) women consecutively diagnosed with breast cancer, we detected one of four analyzed CHEK2 mutations: I157T, 1100delC, IVS2 + 1G > A or del5395. Together they were not associated with the increased risk of breast cancer (North-Central control group: OR = 1.6, p = 0.124; the general Polish population: OR = 1.4, p = 0.109). This association was only seen for IVS2 + 1G > A mutation (OR = 3.0; p = 0.039). One of the three truncating CHEK2 mutations (IVS2 + 1G > A, 1100delC, del5395) was present in 9 of 420 women diagnosed with breast cancer (2.1%) and in 4 of 121 women (3.3%) with a history of breast cancer in a first- and/or second- degree relatives. Together they were associated with the increased risk of disease in these groups, compared to the general Polish population (OR = 2.1, p = 0.053 and OR = 3.2; p = 0.044, respectively). I157T mutation was detected in 25 of 420 women diagnosed with breast cancer (6.0%) and in 8 of 121 women (6.6%) with a history of breast cancer in first- and/or second- degree relatives. The prevalance of I157T mutation was 4.1% (18/435) in North-Central control group and 4.8% (265/5.496) in the general Polish population. However it was not associated with an increased risk of breast cancer.

Conclusion

Obtained results suggest that CHEK2 mutations could potentially contribute to the susceptibility to breast cancer. The germline mutations of CHEK2, especially the truncating ones confer low-penetrance breast cancer predisposition that contribute significantly to familial clustering of breast cancer at the population level.     

Clinical Application of the FoundationOne CDx Assay to Therapeutic Decision-Making for Patients with Advanced Solid Tumors

BackgroundImplementation of personalized medicine requires the accessibility of tumor molecular profiling in order to allow prioritization of appropriate targeted therapies for individual patients. Our aim was to study the role of comprehensive genomic profiling assays that may inform treatment recommendations for patients with solid tumors.Materials and MethodsWe performed a prospective study to evaluate the feasibility of application of the FoundationOne CDx panel—which detects substitutions, insertions and deletions, and copy number alterations in 324 genes, select gene rearrangements, and genomic signatures including microsatellite instability and tumor mutation burden (TMB)—to patients with advanced or recurrent solid tumors before its approval in Japan.ResultsA total of 181 samples were processed for genomic testing between September 2018 and June 2019, with data being successfully obtained for 175 of these samples, yielding a success rate of 96.7%. The median turnaround time was 41 days (range, 21–126 days). The most common known or likely pathogenic variants were TP53 mutations (n = 113), PIK3CA mutations (n = 33), APC mutations (n = 32), and KRAS mutations (n = 29). Among the 153 patients assessed for TMB, the median TMB was 4 mutations/Mb, and tumors with a high TMB (≥10 mutations/Mb) were more prevalent for lung cancer (11/32) than for other solid tumor types (9/121, Fisher''s exact test p < .01). No clear trend toward increased efficacy for immune checkpoint inhibitor (ICI) monotherapy or ICI combination chemotherapy in patients with a high programmed cell death–ligand 1 tumor proportion score or a high TMB was apparent. Among the 174 patients found to harbor known or likely pathogenic actionable alterations, 24 individuals (14%) received matched targeted therapy.ConclusionThe FoundationOne CDx assay was performed with formalin‐fixed, paraffin‐embedded tumor specimens with a success rate of >95%. Such testing may inform the matching of patients with cancer with investigational or approved targeted drugs.Implications for PracticeThis prospective cohort study was initiated to investigate the feasibility and utility of clinical application of FoundationOne CDx. A total of 181 samples were processed for genomic testing between September 2018 and June 2019, with data being successfully obtained for 175 of these samples, yielding a success rate of 96.7%, and 24 individuals (14%) received matched targeted therapy.     

No evidence of correlation between mutation at codon 531 of src and the risk of colon cancer in Chinese

The protein tyrosine kinase activity of c-src proto-oncogene product, pp60^c-src, is elevated in a number of human cancers, including colon cancer. Phosphorylation of human pp60^c-src carboxy-terminal tyrosine 530 suppresses its kinase activity. A recent report suggested that the risk of colon cancer is higher for those who carry a C→T transition mutation on codon 531 (Gln-531→Amber-531) of src gene. This mutation caused a prematured translation termination and up-regulated the kinase activity. To examine whether this mutation could be a risk factor for colon carcinoma in the Chinese population, we used the same PCR-based assay to analyze src genotypes of 131 colon cancers and other various types of carcinoma. No mutation was detected in all specimens that were screened in this study. Thus, mutation at Gln-531 of src gene does not seem to be involved in the development of colon cancer in Chinese ethnicity.     

Regulatory polymorphisms of multidrug resistance 1 (MDR1) gene are associated with the development of childhood acute lymphoblastic leukemia

The aim of this study is to determine whether the polymorphisms of the MDR1 gene are associated with the development of childhood acute lymphoblastic leukemia (ALL).

The MDR1 gene polymorphisms, −2352 G > A, −934A > G, −692T > C (5′ regulatory region) and 3435C > T (exon 26), were examined in 157 ALL patients and 96 healthy children. The amounts of MDR1 mRNA were quantified in 54 healthy individuals using normal peripheral blood mononuclear cells to evaluate the effect of each polymorphism on the gene expression.

The frequency of the G/G genotype of the −2352 G > A was significantly higher in ALL than in controls (74/109 versus 52/96, p = 0.04). The frequency of the T/T genotype of the 3435C > T was also significantly higher in ALL (29/118 versus 10/96, p = 0.006). In a haplotype analysis using the 5′ regulatory sites, the frequency of a certain haplotype was higher in ALL than in controls (59/90 versus 42/88, p = 0.048). When the −2352G > A was examined in different age groups, patients aged six or older were found to have the G/G genotype more frequently than the controls (42/51 versus 52/96, p = 0.0014), while no difference was observed in the younger age group. The amounts of MDR1 mRNA were significantly higher in either G/G or G/A genotype of the −2352 G > A than in A/A genotype (p = 0.04).

The present study suggests that the genetic background of MDR1 may be associated with the development of childhood ALL, possibly due to a quantitative change in the MDR1 gene resulting from genetic polymorphisms.     

KRAS or BRAF mutation status is a useful predictor of sensitivity to MEK inhibition in ovarian cancer

This study examined the status of KRAS and BRAF mutations, in relation to extracellular signal-regulated protein kinase (ERK) activation in 58 ovarian carcinomas to clarify the clinicopathological and prognostic significance of KRAS/BRAF mutations. Somatic mutations of either KRAS or BRAF were identified in 12 (20.6%) out of 58 ovarian carcinomas. The frequency of KRAS/BRAF mutations in conventional serous high-grade carcinomas (4.0% : 1/25) was significantly lower than that in the other histological type (32.3% : 10/31). Phosphorylated ERK1/2 (p-ERK1/2) expression was identified in 18 (38.2%) out of 45 ovarian carcinomas. KRAS/BRAF mutation was significantly correlated with International Federation of Gynecology and Obstetrics (FIGO) stage I, II (P<0.001), and p-ERK1/2 (P<0.001). No significant correlations between KRAS/BRAF mutations or p-ERK1/2 expression and overall survival were found in patients with ovarian carcinoma treated with platinum and taxane chemotherapy (P=0.2460, P=0.9339, respectively). Next, to clarify the roles of ERK1/2 activation in ovarian cancers harbouring KRAS or BRAF mutations, we inactivated ERK1/2 in ovarian cancer cells using CI-1040. Cl-1040 is a compound that selectively inhibits MAP kinase kinase (MEK), an upstream regulator of ERK1/2, and thus prevents ERK1/2 activation. Profound growth inhibition and apoptosis were observed in CI-1040-treated cancer cells with mutations in either KRAS or BRAF in comparison with the ovarian cancer cells containing wild-type sequences. This was evident in both in vitro and in vivo studies. The findings in this study indicate that an activated ERK1/2 pathway is critical to tumour growth and survival of ovarian cancers with KRAS or BRAF mutations. Furthermore, they suggest that the CI-1040-induced phenotypes depend on the mutational status of KRAS and BRAF in ovarian cancers. Therefore, ovarian cancer patients with KRAS or BRAF mutations may benefit from CI-1040 treatment.     

Oncogenic GNAQ mutations are not correlated with disease-free survival in uveal melanoma

Background:

Recently, oncogenic G protein alpha subunit q (GNAQ) mutations have been described in about 50% of uveal melanomas and in the blue nevi of the skin.

Methods:

GNAQ exon 5 was amplified from 75 ciliary body and choroidal melanoma DNAs and sequenced directly. GNAQ mutation status was correlated with disease-free survival (DFS), as well as other clinical and histopathological factors, and with chromosomal variations detected by FISH and CGH.

Results:

Of the 75 tumour DNA samples analysed, 40 (53.3%) harboured oncogenic mutations in GNAQ codon 209. Univariate and multivariate analysis showed that GNAQ mutation status was not significantly correlated with DFS.

Conclusion:

The GNAQ mutation status is not suitable to predict DFS. However, the high frequency of GNAQ mutations may render it a promising target for therapeutic intervention.