Parvalbumin+ and Npas1+ Pallidal Neurons Have Distinct Circuit Topology and Function.

The external globus pallidus (GPe) is a critical node within the basal ganglia circuit. Phasic changes in the activity of GPe neurons during movement and their alterations in Parkinson's disease (PD) argue that the GPe is important in motor control. Parvalbumin-positive (PV+) neurons and Npas1+ neurons are the two principal neuron classes in the GPe. The distinct electrophysiological properties and axonal projection patterns argue that these two neuron classes serve different roles in regulating motor output. However, the causal relationship between GPe neuron classes and movement remains to be established. Here, by using optogenetic approaches in mice (both males and females), we showed that PV+ neurons and Npas1+ neurons promoted and suppressed locomotion, respectively. Moreover, PV+ neurons and Npas1+ neurons are under different synaptic influences from the subthalamic nucleus (STN). Additionally, we found a selective weakening of STN inputs to PV+ neurons in the chronic 6-hydroxydopamine lesion model of PD. This finding reinforces the idea that the reciprocally connected GPe-STN network plays a key role in disease symptomatology and thus provides the basis for future circuit-based therapies.SIGNIFICANCE STATEMENT The external pallidum is a key, yet an understudied component of the basal ganglia. Neural activity in the pallidum goes awry in neurologic diseases, such as Parkinson's disease. While this strongly argues that the pallidum plays a critical role in motor control, it has been difficult to establish the causal relationship between pallidal activity and motor function/dysfunction. This was in part because of the cellular complexity of the pallidum. Here, we showed that the two principal neuron types in the pallidum have opposing roles in motor control. In addition, we described the differences in their synaptic influence. Importantly, our research provides new insights into the cellular and circuit mechanisms that explain the hypokinetic features of Parkinson's disease.

Epidemiologic factors that predict long-term survival following a diagnosis of epithelial ovarian cancer.

BACKGROUND: Various epidemiologic factors have been shown to influence the risk of ovarian cancer development. Given the high fatality associated with this disease, it is of interest to evaluate the association of prediagnostic hormonal, reproductive, and lifestyle exposures with ovarian cancer-specific survival. METHODS: We included 1421 patients with invasive epithelial ovarian cancer diagnosed in Ontario, Canada. Clinical information was obtained from medical records and prediagnostic exposure information was collected by telephone interview. Survival status was determined by linkage to the Ontario Cancer Registry. Proportional hazards regression was used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for ovarian cancer-specific mortality associated with each exposure. Analyses were stratified by histologic subtype to further investigate the associations of risk factors on ovarian cancer-specific mortality. RESULTS: After a mean follow-up of 9.48 years (range 0.59-20.32 years), 655 (46%) women had died of ovarian cancer. Parity (ever) was associated with a significant 29% decreased mortality risk compared with nulliparity (HR=0.71; 95% CI 0.54-0.93; P=0.01). There was a borderline significant association between ever use of oestrogen-containing hormone replacement therapy (HRT) and mortality (HR=0.79; 95% CI 0.62-1.01; P=0.06). A history of cigarette smoking was associated with a significant 25% increased risk of death compared with never smoking (HR=1.25; 95% CI 1.01-1.54; P=0.04). Women with a greater cumulative number of ovulatory cycles had a significantly decreased risk of ovarian cancer-specific death (HR=0.63; 95% CI 0.43-0.94; P=0.02). Increasing BMI (kg m-2) 5 years before diagnosis was associated with an increased risk of death (HR=1.17; 95% CI 1.07-1.28; P=0.0007). Other hormonal or lifestyle factors were not significantly associated with ovarian cancer-specific mortality. CONCLUSIONS: Parity, ovulatory cycles, smoking, and BMI may affect survival following the diagnosis of ovarian cancer. Whether or not oestrogen-containing HRT use is beneficial for survival requires further evaluation.

Frequency of germline PALB2 mutations among women with epithelial ovarian cancer.

Recent studies suggest that mutations in the partner and localizer of BRCA2 (PALB2) gene may predispose to ovarian cancer. It is of importance to clarify the prevalence and penetrance of PALB2 mutations in an unselected population so that clinical recommendations for prevention can be implemented. We evaluated the prevalence of germline mutations in PALB2 among 1421 epithelial ovarian cancer patients and 4300 European controls from the National Heart, Lung, and Blood Institute's Exome Sequencing Project dataset. Clinical information was obtained from medical records and survival status was determined by linkage. PALB2 coding exons were sequenced using next generation sequencing technology. Of the 1421 patients, three (0.21 %) had a germline PALB2 mutation compared to two of the 4300 control subjects (0.05 %). The mean age at diagnosis was 59 years (range 55-62) and all three women died within 2 years of diagnosis. A PALB2 mutation was associated with a four-fold, albeit not significant, increased risk of ovarian cancer (OR = 4.55; 95 % CI 0.76-27.24; P = 0.10). These results suggest that germline PALB2 mutations are rare. The true effect of such mutations on ovarian cancer risk require further study before the clinical relevance of inherited PALB2 mutations is established.

Blunted mGluR Activation Disinhibits Striatopallidal Transmission in Parkinsonian Mice.

The prevailing circuit model predicts that hyperactivity of the striatopallidal pathway and subsequently increased inhibition of external globus pallidus (GPe) neurons lead to the hypokinetic symptoms of Parkinson's disease (PD). It is believed that hyperactivity of the striatopallidal pathway is due to inactivity of dopamine receptors on the somatodendritic membrane of striatopallidal neurons, but the exact cellular underpinnings remain unclear. In this study, we show that mouse GPe astrocytes critically control ambient glutamate level, which in turn gates striatopallidal transmission via the activation of presynaptic metabotropic glutamate receptors. This presynaptic inhibition of striatopallidal transmission is diminished after the chronic loss of dopamine. Elevation of intracellular glutamate content in astrocytes restores the proper regulation of the striatopallidal input in PD models. These findings argue that astrocytes are key regulators of the striatopallidal synapse. Targeting this cell class may serve as an alternative therapeutic strategy for PD.

Ten-year survival after epithelial ovarian cancer is not associated with BRCA mutation status.

OBJECTIVES: After a diagnosis of ovarian cancer, positive BRCA mutation status confers a transient mortality benefit that diminishes with time. The majority of women who survive for 10-12 years are effectively cured of their disease. Thus, it is important to estimate the probability of long-term survival by BRCA mutation status and treatment-related factors. METHODS: We included unselected epithelial ovarian cancers diagnosed in Ontario, Canada from 1995 to 1999 and from 2002 to 2004. Clinical information was obtained from medical records. Survival status was determined by linkage to the Ontario Cancer Registry. We estimated the annual mortality for these patients. We compared women who did and did not survive 10 years for a range of factors including BRCA mutation status and extent of residual disease post-surgery. RESULTS: Of the 1421 patients, 109 (7.7%) had BRCA1 mutations and 68 (4.8%) had BRCA2 mutations. A status of no residual disease was achieved by 39% of non-carriers and 19% of mutation carriers (P<0.0001). By 10-years of follow-up, 43% of non-carriers, 57% of BRCA1 mutation carriers and 69% of BRCA2 mutation carriers had died from ovarian cancer. Among women with stage III/IV serous cancers and no residual disease, the 10-year actuarial survival was 42% for non-carriers and 29% for mutation carriers (P=0.40). CONCLUSION: The initial survival advantage among women with BRCA mutations may reflect a higher initial sensitivity of BRCA carriers to chemotherapy, but this response does not predict long-term survival. The strongest predictor of long-term survival is status of no residual disease at resection.

Ovarian cancer survival by tumor dominance, a surrogate for site of origin.

OBJECTIVES: Recent studies suggest that a proportion of ovarian tumors may actually originate in the distal fallopian tube. The objective of this study was to examine the relationship between dominance (a surrogate for site of origin) and survival, following a diagnosis of epithelial ovarian cancer. METHODS: We classified 1,386 tumors as dominant (putatively originating in the ovary) and non-dominant (putatively originating in the fallopian tube), using parameters obtained from pathology reports. Dominant tumors were restricted to one ovary or one involved ovary that exceeded the other in dimension by at least twofold, while non-dominant tumors were identified as having a greater likelihood of a tubal origin if the disease was equally distributed across the ovaries. Cox proportional hazards models were used to estimate the hazard ratios (HRs) and 95% confidence intervals (CIs) associated with dominance. RESULTS: Non-dominant tumors were more likely to be serous, stage III/IV, and be associated with a BRCA1/2 mutation, increasing parity and use of estrogen hormone replacement therapy (p ≤ 0.01). In contrast, 46 and 26% of the dominant tumors were serous and endometrioid, respectively, with a more even distribution of stage (p < 0.0001). Women with a non-dominant tumor had an increased risk of death compared to women with a dominant tumor (multivariate HR 1.28; 95% CI 1.02-1.60). Findings were similar in our analysis restricted to serous only subtypes (HR 1.28; 95% CI 1.01-1.63). CONCLUSION: These preliminary findings suggest significantly worse survival among women diagnosed with a tumor putatively arising from fallopian tube.

Telomere length and mortality following a diagnosis of ovarian cancer.

BACKGROUND: Telomeres are essential for the maintenance of chromosomal integrity. Telomere shortening leads to genomic instability, which is hypothesized to play a role in cancer development and prognosis. No studies to date have evaluated the prognostic significance of telomere length for ovarian cancer. METHODS: We examined whether relative telomere length in peripheral blood leukocytes was associated with survival following a diagnosis of ovarian cancer. We analyzed data from a large population-based study of incident ovarian cancer conducted in Ontario between 1995 and 2004. Telomere length was measured using the quantitative PCR-based relative telomere length assay and vital status was determined by computerized record linkage and by chart review (n = 1,042). Proportional hazard models were used to estimate ovarian cancer-specific survival HRs and 95% confidence intervals (CI) associated with quartiles of telomere length z score. RESULTS: We found no significant relationship between telomere length and ovarian cancer-specific mortality (P log-rank test = 0.55). Compared with women in the lowest quartile of telomere length z score, the HR for women in the highest three quartiles of telomere length z score combined was 0.88 (95% CI, 0.77-1.10). The corresponding estimates for serous and nonserous tumors were 0.68 (95% CI, 0.66-1.13) and 1.13 (95% CI, 0.71-1.79), respectively. CONCLUSIONS: Our data provide preliminary evidence that telomere length likely does not predict outcome after a diagnosis of ovarian cancer. IMPACT: This represents the first study to suggest no prognostic role of telomere length for ovarian cancer.

Long-term ovarian cancer survival associated with mutation in BRCA1 or BRCA2.

BACKGROUND: Studies have suggested that the 5-year survival of women with ovarian cancer and a BRCA1 or BRCA2 mutation is better than expected. We sought to evaluate the impact of carrying a BRCA1 or BRCA2 mutation on long-term survival of women after a diagnosis of invasive ovarian cancer. METHODS: One thousand six hundred twenty-six unselected women diagnosed with invasive ovarian cancer in Ontario, Canada, or in Tampa, Florida, between 1995 and 2004 were followed for a mean of 6.9 years (range = 0.3 to 15.7 years). Mutation screening for BRCA1 and BRCA2 revealed mutations in 218 women (13.4%). Left-truncated survival analysis was conducted to estimate ovarian cancer-specific survival at various time points after diagnosis for women with and without mutations. RESULTS: In the 3-year period after diagnosis, the presence of a BRCA1 or BRCA2 mutation was associated with a better prognosis (adjusted hazard ratio = 0.68, 95% confidence interval [CI] = 0.48 to 0.98; P = .03), but at 10 years after diagnosis, the hazard ratio was 1.00 (95% CI = 0.83 to 1.22; P = .90). Among women with serous ovarian cancers, 27.4% of women who were BRCA1 mutation carriers, 27.7% of women who were BRCA2 carriers, and 27.1% of women who were noncarriers were alive at 12 years past diagnosis. CONCLUSION: For women with invasive ovarian cancer, the short-term survival advantage of carrying a BRCA1 or BRCA2 mutation does not lead to a long-term survival benefit.

Height, weight, BMI and ovarian cancer survival.

OBJECTIVES: Ovarian cancer is a highly fatal gynecologic malignancy. Prognosis is primarily based on clinicopathologic features. There is interest in the role of modifiable factors including overweight and obesity, although data to date have been inconclusive. Here we evaluate the relationship between body size and ovarian cancer survival among 1423 women diagnosed with epithelial ovarian cancer in a large population-based study. METHODS: Information on risk factors and characteristics was collected by telephone. Vital status was determined both by computerized record-linkage and by chart review. Cox proportional hazards models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for height, weight and body mass index (BMI) in association with ovarian cancer-specific mortality. RESULTS: Height, weight and BMI 5 years prior to diagnosis did not significantly predict ovarian cancer survival in this study. The HR for ovarian cancer-specific mortality for women with a weight of >61 kg compared with >50-55 kg was 0.91 (95%CI 0.71-1.20). The HR among women with a BMI≥30 kg/m2 compared to 18.5-<25 kg/m2 was 1.11 (95%CI 0.87-1.42). These findings did not vary by histologic subtype. CONCLUSIONS: Our results do not support a role of height, adult weight or adiposity in ovarian cancer prognosis.

Clinical impact of unclassified variants of the BRCA1 and BRCA2 genes.

Women who carry a pathogenic mutation in BRCA1 or BRCA2 have high risks of developing breast and ovarian cancers. The functional effect of many missense variants on BRCA1 and BRCA2 protein function is not known. Here, the authors construct a historical cohort of 4030 female first-degree relatives of 1345 unselected patients with ovarian cancer who have been screened for BRCA1 and BRCA2 mutations. The authors compared the risks by the age of 80 years for all cancers combined in female first-degree relatives of women with a pathogenic mutation, women with a variant of unknown significance (unclassified variant) and non-carriers. The cumulative risk of cancer among the relatives of patients with a pathogenic mutation was much higher than the risk in relatives of non-carriers (50.2% vs 28.5%; HR=2.87, p<10(-4)). In contrast, the cumulative risk of cancer among relatives of patients carrying an unclassified variant was similar to the risk of cancer for relatives of non-carriers (27.6% vs 28.5%; HR=1.08, p=0.79). The authors used three different algorithms to predict the pathogenicity of unclassified variants and compared their penetrance with non-carriers. In this sample, only Align Grantham Variation Grantham Deviation appeared to predict penetrance based on first-degree relatives.

Frequencies of BRCA1 and BRCA2 mutations among 1,342 unselected patients with invasive ovarian cancer.

BACKGROUND: The heritable fraction of ovarian cancer exceeds that of any other common adult cancer. Most inherited cases of ovarian cancer are due to a germline mutation in BRCA1 or BRCA2. It is important to have an accurate estimate of the proportion of ovarian cancer patients who carry a mutation and the specific factors which predict the presence of a mutation. METHODS: We tested a population-based series of 1342 unselected patients diagnosed with invasive ovarian cancer between 1995-1999 and 2002-2004 in Ontario, Canada, for germline mutations in BRCA1 and BRCA2. The two genes were tested in their entirety, using a range of techniques, including multiplex ligation-dependent probe amplification (MLPA). RESULTS: Among the 1342 women, 176 women carried a mutation (107 in BRCA1, 67 in BRCA2, and two in both genes) for a combined mutation frequency of 13.3%. Seven deletions were identified using MLPA (3.9% of all detected mutations). The prevalence of mutations was particularly high among women diagnosed in their forties (24.0%), in women with serous ovarian cancer (18.0%) and women of Italian (43.5%), Jewish (30.0%) or Indo-Pakistani origin (29.4%). A mutation was seen in 33.9% of women with a first-degree relative with breast or ovarian cancer and in 7.9% of women with no first-degree relative with breast or ovarian cancer. No mutation was seen in women with mucinous carcinoma. CONCLUSIONS: BRCA1 and BRCA2 mutations are common in women with invasive ovarian cancer. All women diagnosed with invasive non-mucinous ovarian cancer should be considered to be candidates for genetic testing.

Prevalence of BRCA1 and BRCA2 germ line mutations among women with carcinoma of the fallopian tube.

OBJECTIVES: The purpose of this study is to determine the prevalence of BRCA1 and BRCA2 mutations among a large series of women with carcinoma of the fallopian tube. METHODS: Two series of women diagnosed with carcinoma of the fallopian tube were studied. Women identified from the Ontario Cancer Registry who were diagnosed with fallopian tube cancer between 1990 and 1998 and between 2002 and 2004. A second, hospital-based series was identified at Cedars Sinai Medical Centre, Los Angeles, California. These women were diagnosed between 1991 and 2007. Each subject was approached to provide her family history and ethnic background and to provide a blood sample for genetic testing for mutations in the BRCA1 and BRCA2 genes. RESULTS: In total, 108 patients with fallopian tube cancer were recruited (70 from Ontario and 38 from Los Angeles). Thirty-three patients (30.6%) were found to have a deleterious mutation; 23 in BRCA1 (21.3%) and 10 in BRCA2 (9.3%). The prevalence of mutations was 55.6% in Jewish women and was 26.4% in non-Jewish women. A family history of ovarian or breast cancer was positive for 24 women (23.3%); of these, 14 had a mutation (58.3%). Fourteen (14.4%) of the patients had a previous history of breast cancer; of these, 10 (71.4%) had a mutation. 40.3% of the women who were diagnosed with fallopian tube cancer before age 60 had a mutation, compared with 17.4% of the women diagnosed at age 60 and above. CONCLUSIONS: Approximately 30% of women with fallopian tube cancer have a mutation in BRCA1 or BRCA2. The highest frequencies of BRCA mutations were seen in women with fallopian tube cancer diagnosed under age 60, in Jewish women, in women with a family history of breast or ovarian cancer, and in women with a personal history of breast cancer. All patients diagnosed with invasive fallopian tube cancer should be considered candidates for genetic testing.

Risk factors for carcinoma of the fallopian tube in women with and without a germline BRCA mutation.

OBJECTIVE: The purpose of this study was to identify risk factors for fallopian tube cancer in women with and without a BRCA mutation. METHODS: Subjects with fallopian tube cancer were identified from two sources: 1) a large international registry of women who carry a BRCA1 or BRCA2 mutation (n=56), and; 2) a population-based study of ovarian and fallopian tube cancer conducted in Ontario, Canada (n=66). BRCA mutation status was established for all subjects. Each subject was matched to one or more unaffected controls, for date of birth (within four years), for BRCA mutation status (negative, BRCA1, and BRCA2), for country of residence and for past history of breast cancer (yes/no). All subjects completed a questionnaire about medical history and lifestyle factors. Odds ratios and 95% confidence intervals were calculated for parity, oral contraceptive use, tubal ligation, hormone replacement therapy and body mass index, using conditional logistic regression. RESULTS: We studied 103 women with fallopian tube cancer (48 with a BRCA1 mutation, 12 with a BRCA2 mutation and 43 with no identified BRCA mutation) and 980 matched controls. Increasing parity was associated with a decreased risk of fallopian tube cancer in non-carriers (trend per birth odds ratio 0.71 (95% CI 0.52-0.97), p=0.03), in BRCA1 carriers (OR=0.79 (0.62-1.02) p=0.07) and in BRCA2 carriers (OR=0.62 (0.34-1.15), p=0.13), but was statistically significant only for non-carriers. Oral contraceptive use was associated with a reduced risk in BRCA1 carriers (trend per year of use odds ratio=0.91 (0.83-0.99), p=0.03) but not for non-carriers (OR=0.97 (0.87-1.09), p=0.64) or for BRCA2 carriers (OR=0.94 (0.80-1.11), p=0.47). Hormone replacement therapy was associated with an increased risk for fallopian tube cancer in all subjects (OR=1.07 (1.01-1.13), p=0.03), and in the subgroups stratified by mutation, however the association was not significant in the subgroups. Tubal ligation was associated with a decreased risk of fallopian tube cancer for all subjects (OR=0.64 (0.31-1.28), p=0.21), however the reduction was not significant. CONCLUSIONS: Parity and oral contraceptive use are associated with reduced risks of fallopian tube cancer. In contrast, hormone replacement therapy may be associated with an increase in the risk of fallopian tube cancer.

Uptake of clinical genetic testing for ovarian cancer in Ontario: a population-based study.

BACKGROUND: Approximately 13% of ovarian cancers in Canada are attributable to a mutation in BRCA1 or BRCA2. In 2001, genetic testing for BRCA1 and BRCA2 became freely available to all women in Ontario with a diagnosis of invasive ovarian cancer. It is unknown what proportion of women with ovarian cancer receive genetic testing as a result of this recommendation. METHODS: Patients in Ontario who had been diagnosed with epithelial ovarian cancer from 2002 to 2004 were identified using the Ontario Cancer Registry. Information was collected on demographic and risk factors, including information on previous testing for BRCA1 and BRCA2. Women were asked to provide a blood sample for genetic testing or to provide a genetic test result if clinical testing had been done. Genetic testing for BRCA1 and BRCA2 mutations was conducted on all blood samples. RESULTS: Of the 416 women, 80 women (19%) had undergone previous clinical genetic testing for BRCA1 and BRCA2. Of these 80 women, 30% had a positive genetic test result, compared to 5% of 336 women who had not had clinical genetic testing (p<0.0001). Sixty percent of all mutations were identified within this group of 80 women. CONCLUSIONS: Genetic testing is available in Ontario to all women with invasive ovarian cancer. However, only a small proportion of women are being referred for testing. This study suggests that increased public awareness directed at physicians and at women with cancer may expand the use of genetic testing.

Population BRCA1 and BRCA2 mutation frequencies and cancer penetrances: a kin-cohort study in Ontario, Canada.

BACKGROUND: BRCA1 and BRCA2 mutations in general populations and in various types of cancers have not been well characterized. We investigated the presence of these mutations in unselected patients with newly diagnosed incident ovarian cancer in Ontario, Canada, with respect to cancers reported among their relatives. METHODS: A population series of 1171 unselected patients with incident ovarian cancer diagnosed between January 1, 1995, and December 31, 1999, in Ontario, Canada, was screened for germline mutations throughout the BRCA1 and BRCA2 genes. Screening involved testing for common variants, then protein truncation testing of long exons, and then denaturing gradient gel electrophoresis or denaturing high-performance liquid chromatography for the remainder of BRCA1 and BRCA2, respectively. Cox regression analysis was used to examine cancer outcomes reported by the case probands for their 8680 first-degree relatives. Population allele frequencies and relative risks (RRs) were derived from the regression results by an extension of Saunders-Begg methods. Age-specific Ontario cancer incidence rates were used to estimate cumulative incidence of cancer to age 80 years by mutation status. RESULTS: Among 977 patients with invasive ovarian cancer, 75 had BRCA1 mutations and 54 had BRCA2 mutations, for a total mutation frequency of 13.2% (95% confidence interval [CI] = 11.2% to 15.5%). Higher risks for various cancer types in the general Ontario population were associated with BRCA1 mutation carriage than with noncarriage, including ovarian (RR = 21, 95% CI = 12 to 36), female breast (RR = 11, 95% CI = 7.5 to 15), and testis (RR = 17, 95% CI = 1.3 to 230) cancers. Higher risks were also associated with BRCA2 mutation carriage than with noncarriage, particularly for ovarian (RR = 7.0, 95% CI = 3.1 to 16), female and male breast (RR = 4.6, 95% CI = 2.7 to 7.8, and RR = 102, 95% CI = 9.9 to 1050, respectively), and pancreatic (RR = 6.6, 95% CI = 1.9 to 23) cancers. Cancer risks differed according to the mutation's position in the gene. Estimated cumulative incidence to age 80 years among women carrying BRCA1 mutations was 24% for ovarian cancer and 90% for breast cancer and among women carrying BRCA2 mutations was 8.4% for ovarian cancer and 41% for breast cancer. For the general Ontario population, estimated carrier frequencies of BRCA1 and BRCA2 mutations, respectively, were 0.32% (95% CI = 0.23% to 0.45%) and 0.69% (95% CI = 0.43% to 1.10%). CONCLUSIONS: BRCA1 and BRCA2 mutations may be more frequent in general populations than previously thought and may be associated with various types of cancers.