Biomedical subjects

Jenny N Poynter

Publications and source records attributed to Jenny N Poynter.

6 recordsLinked to original sources

PubMed2026

Overlapping genetic etiology of pediatric and adult germ cell tumors.

BACKGROUND: Germ cell tumors are heterogeneous neoplasms arising from primordial germ cells. Although genome-wide association studies have identified numerous susceptibility loci for adult testicular germ cell tumors, the heritable basis of pediatric testicular germ cell tumors and germ cell tumors that arise outside the testes remain poorly understood. METHODS: We conducted a multi-ancestry genome-wide association study of pediatric germ cell tumors, including 1927 cases from the Germ Cell Tumor Epidemiology Study and 10 601 controls. Cases were diagnosed with testicular (n = 678), ovarian (n = 441), intracranial (n = 435), and extragonadal (n = 373) germ cell tumor between the ages of 0 and 19 years. RESULTS: We identified 4 loci reaching genome-wide significance, including variants near BAK1 (chr 6: rs3831846), SPRY4 (chr 5: rs12515244), DMRT1 (chromosome [chr] 9: rs10815910), and DEPTOR (chr 8: rs13277786). Additional genome-wide statistically significant associations were identified in subgroup analyses, including 6 loci for intracranial germ cell tumors (rs2758612 [PMF1/BGLAP], rs9854760 [PLCL2], rs6851498 [KIT], rs11816992 on chromosome 10, rs3830273 [TFAM], and rs13054014 [LZTR1]), 1 locus for testicular germ cell tumor (rs1907702 [KITLG]), and 1 locus for males (rs4610628 [MAD1L1]). After Bonferroni correction, 18 of 78 previously reported testicular germ cell tumor loci were significantly associated with germ cell tumor overall or in at least 1 subgroup with a particularly strong correlation between testicular germ cell tumor and intracranial germ cell tumor effect estimates (rho = 0.63, P = 5.5 × 10-10). Expression quantitative trait locus (QTL) analyses identified candidate genes in the regions identified on chromosome 6 (BAK1, LINC003366, and ITPR3) and chromosome 8 (DEPTOR and RP11-760H22.2). CONCLUSIONS: Our data support a role for germline genetic variation in the development of germ cell tumors in locations outside the testes and highlight shared genetic architecture across age group and tumor location.

Humans↗

PubMed2006

BRAF and NRAS mutations in spitzoid melanocytic lesions.

BRAF mutations are common events in a variety of melanocytic nevi and primary cutaneous melanomas. We have previously found BRAF mutations in 82% of nevi, consisting of congenital, common acquired and dysplastic types, and 33% of primary cutaneous melanomas other than the spitzoid type, similar to other published reports. A small number of studies have evaluated Spitz nevi and have failed to detect any lesions possessing a BRAF mutation. Only one study included categories of atypical Spitz nevus and borderline lesions suspected to be spitzoid melanomas, along with classic Spitz nevi and spitzoid melanomas. We examined a spectrum of spitzoid lesions that included 48 Spitz nevi, some with atypical features, seven atypical (borderline) Spitz tumors, and 13 spitzoid melanomas. BRAF mutations were detected in 12 of 68 spitzoid lesions, of which two were spitzoid melanomas and 10 were Spitz nevi. Five of the 10 Spitz nevi with BRAF mutations were altered by more than usual cytologic atypia and/or architectural atypia overlapping with dysplastic nevi, or irritation/inflammation; one desmoplastic Spitz nevus had a BRAF mutation. These results indicate that a small subset of Spitz nevi, some with atypical histologic features, possess BRAF mutations. Therefore, the BRAF mutational status does not separate all Spitz nevi from spitzoid melanomas and non-Spitz types of melanocytic proliferations, contrary to previous reports.

Adolescent↗

PubMed2006

BRAF and NRAS mutations in melanoma and melanocytic nevi.

In this report, we investigated BRAF/NRAS mutations in samples from a case-control study of melanoma and a series of benign melanocytic nevi. We evaluated potential associations between BRAF mutations and histopathologic and pigmentary characteristics of melanoma. Mutations in BRAF and NRAS were detected by sequencing microdissected/laser-captured DNA from 18 in-situ melanomas, 64 primary melanomas, and 51 nevi. Nevi showed the highest frequency of BRAF mutations (82%). BRAF mutations were identified in 29% of invasive melanomas and in only 5.6% of in-situ melanomas. Mutations in NRAS were found in 5.2% of primary melanomas, 5.9% of nevi and no NRAS mutations were seen in in-situ melanomas. A majority of the BRAF mutations observed in primary invasive melanoma were seen in superficial spreading melanoma (15/17), and melanomas with BRAF mutations were also more likely to be found on a body site that was likely to be exposed to intermittent sun exposure compared with chronic or no sun exposure (P=0.02). Tumors with BRAF mutations were also significantly more likely to occur in association with a contiguous nevus (odds ratio 3.49, 95% confidence interval 1.06-11.46), although a contiguous nevus was not found in all melanomas with a BRAF mutation. Our data support the evidence that the mitogen-activated protein kinase pathway is upregulated in a large percentage of melanocytic lesions, but these mutations are not sufficient for malignant transformation. We suggest that BRAF mutations contribute to benign melanocytic hyperplasia, but are likely to contribute to invasive melanoma only in conjunction with other mutations.

Case-Control Studies↗

PubMed2006

APC I1307K and the risk of prostate cancer.

The kin-cohort design has been proposed as an alternative to traditional case-control and cohort measures to evaluate inherited susceptibility to cancer in population-based studies. Here, we used this design to evaluate inherited susceptibility to prostate cancer associated with APC I1307K using data from the Molecular Epidemiology of Colorectal Cancer study. Two techniques were used to compare the incidence of prostate cancer in APC I1307K carriers. First, we compared the incidence of prostate cancer in relatives of mutation carriers and noncarriers using standard techniques for survival analysis. Second, we used the marginal maximum likelihood method for kin-cohort analysis to infer the genotypes in the relatives. We also evaluated APC I1307K in 75 Ashkenazi Jewish individuals with prostate cancer from 27 families enrolled in the University of Michigan Prostate Cancer Genetic Study. We observed a slightly increased risk of prostate cancer in relatives of APC I1307K carriers, however, this difference was not statistically significant (hazard ratio, 1.6; 95% confidence intervals, 0.7-3.4). Similar conclusions were drawn using both techniques for kin-cohort analysis. APC I1307K was found in 7.4% of families genotyped, which is slightly higher than the allele prevalence reported in Ashkenazi Jews in the general population. In addition, we did not observe loss of heterozygosity at APC or a somatic mutation near APC I1307K using microdissected tumor DNA from mutation carriers enrolled in the Prostate Cancer Genetic Study. Overall, the evidence for an association between APC I1307K and prostate cancer is not compelling. APC I1307K is unlikely to play a clinically meaningful role in susceptibility to prostate cancer.

Age Distribution↗

PubMed2005

Statins and the risk of colorectal cancer.

BACKGROUND: Statins are inhibitors of 3-hydroxy-3-methylglutaryl coenzyme A reductase and effective lipid-lowering agents. Statins inhibit the growth of colon-cancer cell lines, and secondary analyses of some, but not all, clinical trials suggest that they reduce the risk of colorectal cancer. METHODS: The Molecular Epidemiology of Colorectal Cancer study is a population-based case-control study of patients who received a diagnosis of colorectal cancer in northern Israel between 1998 and 2004 and controls matched according to age, sex, clinic, and ethnic group. We used a structured interview to determine the use of statins in the two groups and verified self-reported statin use by examining prescription records in a subgroup of patients for whom prescription records were available. RESULTS: In analyses including 1953 patients with colorectal cancer and 2015 controls, the use of statins for at least five years (vs. the nonuse of statins) was associated with a significantly reduced relative risk of colorectal cancer (odds ratio, 0.50; 95 percent confidence interval, 0.40 to 0.63). This association remained significant after adjustment for the use or nonuse of aspirin or other nonsteroidal antiinflammatory drugs; the presence or absence of physical activity, hypercholesterolemia, and a family history of colorectal cancer; ethnic group; and level of vegetable consumption (odds ratio, 0.53; 95 percent confidence interval, 0.38 to 0.74). The use of fibric-acid derivatives was not associated with a significantly reduced risk of colorectal cancer (odds ratio, 1.08; 95 percent confidence interval, 0.59 to 2.01). Self-reported statin use was confirmed for 276 of the 286 participants (96.5 percent) who reported using statins and whose records were available. CONCLUSIONS: The use of statins was associated with a 47 percent relative reduction in the risk of colorectal cancer after adjustment for other known risk factors. Because the absolute risk reduction is likely low, further investigation of the overall benefits of statins in preventing colorectal cancer is warranted.

Aged↗

PubMed2005

Characterization of a human carcinoma cell line selected for resistance to the farnesyl transferase inhibitor 4-(2-(4-(8-chloro-3,10-dibromo-6,11-dihydro-5H-benzo-(5,6)-cyclohepta(1,2-b)-pyridin-11(R)-yl)-1-piperidinyl)-2-oxo-ethyl)-1-piperidinecarboxamide (SCH66336).

Farnesyl protein transferase inhibitors (FTIs) have demonstrated clinical activity in certain solid tumors and hematological malignancies. Little is known about mechanisms of resistance to these agents. To provide a basis for better understanding FTI resistance, the colorectal carcinoma cell line HCT 116 was selected by stepwise exposure to increasing 4-(2-(4-(8-chloro-3,10-dibromo-6,11-dihydro-5H-benzo-(5,6)-cyclohepta(1,2-b)-pyridin-11(R)-yl)-1-piperidinyl)-2-oxo-ethyl)-1-piperidinecarboxamide (SCH66336) concentrations. The resulting line, HCT 116R, was 100-fold resistant to SCH66336 and other FTIs, including methyl {N-[2-phenyl-4-N[2(R)-amino-3-mercaptopropylamino] benzoyl]}-methionate (FTI-277), but was less than 2-fold resistant to the standard agents gemcitabine, cisplatin, and paclitaxel. Accumulation of the unfarnesylated forms of prelamin A and HDJ-2, two substrates that reflect farnesyl transferase inhibition, was similar in FTI-treated parental and HCT 116R cells, indicating that alterations in drug uptake or inhibition of farnesyl protein transferase is not the mechanism of resistance. Changes in signal-transduction pathways that might account for this resistance were examined by immunoblotting and confirmed pharmacologically. There was no difference in activation of the mitogen-activated protein kinase kinase (MEK)/extracellular signal-regulated kinase pathway or sensitivity to the MEK1/2 inhibitor 2'-amino-3'-methoxyflavone (PD98059) in HCT 116R cells. In contrast, increased phosphorylation of the molecular target of rapamycin (mTOR) and its downstream target p70 S6 kinase and increased levels of Akt1 and Akt2 were demonstrated in HCT 116R cells. Further experiments demonstrated that the mTOR inhibitor rapamycin selectively sensitized HCT 116R cells to SCH66336 but not to gemcitabine, cisplatin, or paclitaxel. These findings provide evidence that alterations in the phosphatidylinositol-3 kinase/Akt pathway can contribute to FTI resistance and suggest a potential strategy for overcoming this resistance.

Alkyl and Aryl Transferases↗