Germline whole genome sequencing in adults with multiple primary tumors

Multiple primary tumors (MPTs) are a harbinger of hereditary cancer syndromes. Affected individuals often fit genetic testing criteria for a number of hereditary cancer genes and undergo multigene panel testing. Other genomic testing options, such as whole exome (WES) and whole genome sequencing (WGS) are available, but the utility of these genomic approaches as a second-tier test for those with uninformative multigene panel testing has not been explored. Here, we report our germline sequencing results from WGS in 9 patients with MPTs who had non-informative multigene panel testing. Following germline WGS, sequence (agnostic or 735 selected genes) and copy number variant (CNV) analysis was performed according to the American College of Medical Genetics (ACMG) standards and guidelines for interpreting sequence variants and reporting CNVs. In this cohort, WGS, as a second-tier test, did not identify additional pathogenic or likely pathogenic variants in cancer predisposition genes. Although we identified a CHEK2 likely pathogenic variant and a MUTYH pathogenic variant, both were previously identified in the multigene panels and were not explanatory for the presented type of tumors. CNV analysis also failed to identify any pathogenic or likely pathogenic variants in cancer predisposition genes. In summary, after multigene panel testing, WGS did not reveal any additional pathogenic variants in patients with MPTs. Our study, based on a small cohort of patients with MPT, suggests that germline gene panel testing may be sufficient to investigate these cases. Future studies with larger sample sizes may further elucidate the additional utility of WGS in MPTs.

Genetic testing women with newly diagnosed breast cancer: What criteria are the most predictive of a positive test?

BACKGROUND

Knowledge of pathogenic variants in cancer-predisposing genes is important when making breast cancer treatment decisions, but genetic testing is not universal and criteria must be met to qualify for genetic testing. The objective of this study was to evaluate the pathogenic variant yield for nine cancer predisposition genes by testing criteria, singly and in combination.

METHODS

Women diagnosed with breast cancer between June 2013 and May 2018 were recruited from four centers in Toronto, Canada. Participants completed a demographics and family history questionnaire and clinical characteristics were collected from medical charts. Genetic testing was done for BRCA1, BRCA2, PALB2, ATM, CHEK2, BRIP1, RAD51D, RECQL, and TP53. Pathogenic variant frequencies were calculated according to five criteria (age ≤ 50, triple-negative breast cancer, family history, bilateral breast cancer, or Jewish ethnicity).

RESULTS

Of the 1006 women studied, 100 women (9.9%) were found to have a pathogenic variant in one of the nine genes tested. The highest prevalence of pathogenic variants was found in women with triple-negative breast cancer (23%). Of the 100 pathogenic variants detected, 78 were detected in women diagnosed at age 50 or less. A total of 96% of the mutations were identified with three criteria (age of diagnosis, family history, and triple-negative status).

CONCLUSIONS

Genetic testing criteria for women with breast cancer should include women with triple-negative breast cancer, regardless of age. All women aged 50 years or below at time of breast cancer diagnosis should be offered genetic testing.

Bilateral Oophorectomy and the Risk of Breast Cancer in BRCA1 Mutation Carriers: A Reappraisal

BACKGROUND

The lack of consensus on whether bilateral oophorectomy impacts risk of developing breast cancer among BRCA1 mutation carriers might be attributed to various biases, specifically, cancer-induced testing bias due to inclusion of prevalent cases. We conducted two complementary matched case-control analyses to evaluate the association of oophorectomy and BRCA1 breast cancer.

METHODS

A research questionnaire was administered every two years to collect information on exposures and disease. In the first analysis, we limited the study to prevalent breast cancer cases (diagnosed prior to study entry; n = 2,962) who were matched to controls on year of birth and country of residence (n = 4,358). In the second approach, we limited to 330 incident cases (diagnosed in the follow-up period) and 1,548 matched controls. Conditional logistic regression was used to estimate the adjusted odds ratios (OR) and 95% confidence intervals (CI) of invasive breast cancer.

RESULTS

In the first approach, there was a significant inverse association between oophorectomy and the risk of developing breast cancer [OR = 0.43; 95% confidence interval (CI), 0.34-0.55; P < 00001]. In the second approach, there was no association between oophorectomy and risk (OR = 1.21; 95% CI, 0.87-1.70; P = 0.26).

CONCLUSIONS

The inclusion of women with a personal history of breast cancer prior to ascertainment likely impacts upon the association of oophorectomy and BRCA1 breast cancer risk.

IMPACT

Oophorectomy is unlikely a determinant of breast cancer risk in BRCA1 mutation carriers but should be offered at age 35 to reduce the risk of ovarian and fallopian tube cancer.

Validation of BRCA testing on cytologic samples of high-grade serous carcinoma

BACKGROUND

Testing for BRCA1/2 gene alterations in patients with high-grade serous carcinoma (HGSC) is a critical determinant of treatment eligibility for poly(adenosine diphosphate-ribose) polymerase inhibitors in addition to providing vital information for genetic counselling. Many patients present with effusions necessitating therapeutic drainage, and this makes cytologic specimens (CySs) the initial diagnostic material for HGSC, often before histologic sampling. Initiating somatic BRCA testing on a CyS allows the BRCA status to be determined sooner, and this affects clinical management.

METHODS

Retrospectively, 8 cases of formalin-fixed, paraffin-embedded (FFPE) CySs of peritoneal or pleural fluid from patients with HGSC and known BRCA1/2 alterations previously established by the testing of FFPE surgical specimens (SpSs) underwent next-generation sequencing (NGS). Prospectively, 11 cases of peritoneal or pleural fluid from patients with HGSC but an unknown BRCA1/2 status underwent NGS with fresh, alcohol-fixed, and FFPE CySs, and they were compared with subsequent NGS on 4 SpSs.

RESULTS

CySs yielded high-quantity and high-quality DNA for NGS analysis when sufficient tumor cellularity was present. Fresh, alcohol-fixed, and FFPE CySs were all suitable for NGS and provided identical NGS results. SpS and CyS BRCA testing was concordant in 10 of 12 cases. The 2 discordant cases showed low tumor cellularity and quality in the CyS and the SpS, respectively.

CONCLUSION

Effusion CySs of HGSC are excellent sources for NGS testing for BRCA1/2 genetic alterations when sufficient tumor cellularity is present. Fresh, alcohol-fixed, and FFPE CySs are equivalent for NGS of BRCA1/2. NGS testing of HGSC CySs demonstrates good concordance with SpSs for the BRCA1/2 status.

Tumor and germline next generation sequencing in high grade serous cancer: experience from a large population-based testing program

The aim of this study was to determine the prevalence of somatic and germline pathogenic variants (PVs) in high‐grade serous cancer (HGSC) and to demonstrate the technical feasibility and effectiveness of a large‐scale, population‐based tumor testing program. It involved a retrospective review of genetic test results in 600 consecutive HGSC tumor samples and a subsequent comparison of germline and tumor results in a subset of 200 individuals. Tumor testing was successful in 95% of samples (570/600) with at least one BRCA1/2 PV identified in 16% (93/570) of cases. Among the 200 paired cases, BRCA1/2 PVs were detected in 38 tumors (19%); 58% were somatic (22/38); and 42% were germline (16/38). There was 100% concordance between germline and tumor test results. This is the largest series of BRCA1/2 testing in HGSC (tumor‐only and paired cohorts), reported to date, and our data show that an effectively designed and validated population‐based tumor testing program can be used to determine both treatment eligibility and hereditary cancer risk.

Rapid Genetic Testing for BRCA1 and BRCA2 Mutations at the Time of Breast Cancer Diagnosis: An Observational Study

BACKGROUND

This study aimed to evaluate the impact of rapid genetic testing (RGT) for BRCA1 and BRCA2 at the time of breast cancer diagnosis on treatment choices. Bilateral mastectomy for the treatment of breast cancer in women with a BRCA1 or BRCA2 mutation offers a reduction in the risk of contralateral breast cancer. It is unclear whether offering RGT at the time of breast cancer diagnosis has an impact on women's surgical decision-making.

METHODS

Women with breast cancer diagnosed between June 2013 and May 2018 were recruited from four academic health sciences centers in Toronto, Canada. The participants completed a questionnaire before genetic testing, then one week and one year after disclosure of the genetic test result. Before surgery, RGT was performed. Diagnostic, pathologic, and treatment data were compared between those with and those without a BRCA mutation.

RESULTS

The study enrolled 1007 women who consented to RGT. The mean age of the participants was 46.3 years, and the median time to result disclosure was 10 days. A BRCA mutation was found in 6% of the women. The women with a BRCA mutation were significantly more likely to elect for bilateral mastectomy than the women without a BRCA mutation (p < 0.0001). Of the BRCA-positive patients, 95.7% reported that they used their genetic test result to make a surgical decision.

CONCLUSIONS

The women provided with RGT at the time of breast cancer diagnosis use the genetic information to make treatment decisions, and the majority of those identified with a BRCA mutation elect for a bilateral mastectomy.

Setting a baseline: A 7-year review of referral rates and outcomes for serous ovarian cancer prior to implementation of oncologist mediated genetic testing

OBJECTIVE

Despite guidelines recommending that all women with invasive serous ovarian cancer (SOC) are offered genetic testing, published referral and testing rates have been poor. Many centers have implemented novel genetic counseling service delivery models to increase testing rates. In light of increased awareness and implementation of small process changes at our center, this study aims to establish baseline referral rates and testing outcomes prior to diverging from the traditional model of care.

METHODS

A list of women diagnosed with SOC at Princess Margaret Cancer Center (PM) between 2010 and 2016 was obtained from the PM Cancer Registry and cross-referenced against the genetics database to determine referral rates and outcomes of genetic testing.

RESULTS

Of 724 women with SOC, 68% were referred for genetic counseling, with an overall testing rate of 61%. Higher referral rates were seen among women with younger ages at diagnosis and high-grade tumors. Of women tested, 22% were found to have a pathogenic variant in BRCA1/2 and 9% in another cancer gene. Notably, 24% of women with a pathogenic variant reported no family history of breast or ovarian cancer.

CONCLUSION

Genetic counseling referral and testing rates for women with SOC are higher than previously reported, yet barriers to referral remain. To maximize genetic testing rates and address increasing patient volumes, clinics may be faced with integrating novel genetic counseling delivery models. Findings from this study may serve as a more accurate baseline to which large scale service delivery changes can be compared.

A Canadian guideline on the use of next-generation sequencing in oncology

Rapid advancements in next-generation sequencing (ngs) technology have created an unprecedented opportunity to decipher the molecular profile of tumours to more effectively prevent, diagnose, and treat cancer. Oncologists now have the option to order molecular tests that can guide treatment decisions. However, to date, most oncologists have received limited training in genomics, and they are now faced with the challenge of understanding how such tests and their interpretation align with patient management. Guidance on how to effectively use ngs technology is therefore needed to aid oncologists in applying the results of genomic tests. The Canadian guideline presented here describes best practices and unmet needs related to ngs-based testing for somatic variants in oncology, including clinical application, assay and sample selection, bioinformatics and interpretation of reports performed by laboratories, patient communication, and clinical trials.

The risk of breast cancer in BRCA1 and BRCA2 mutation carriers without a first-degree relative with breast cancer

The objective of this study was to estimate the lifetime risk of breast cancer in women with a BRCA1 or BRCA2 mutation with and without at least 1 first-degree relative with breast cancer. A total of 2835 women with a BRCA1 or BRCA2 mutation were followed. Age- and gene-specific breast cancer rates were calculated. The relative risks of breast cancer for subjects with a family history of breast cancer, compared to no family history were calculated. The mean age at baseline was 41.1 years, and they were followed for a mean of 6.0 years. The estimated penetrance of breast cancer to age 80 years was 60.8% for BRCA1 and 63.1% for BRCA2. For all BRCA carriers, the penetrance of breast cancer to age 80 for those with no first-degree relative with breast cancer was 60.4% and 63.3% for those with at least 1 first-degree relative with breast cancer. The risk of breast cancer for BRCA carriers with no first-degree relative with breast cancer is substantial, and as a result, clinical management for these women should be the same as those for women with an affected relative.

Abstract P3-09-05: Clinical outcome of patients with advanced triple negative breast cancer with germline and somatic variants in homologous recombination gene

Background: Variants in homologous recombination (HR) genes other than BRCA1/2 may cause a BRCA-like phenotype triple negative breast cancer (TNBC), which includes the sensitivity to platinums and DNA repair inhibitors. Evaluation of HR proficiency may influence the clinical management of TNBC. Our aim was to evaluate germline and somatic HR gene variants in advanced TNBC patients (pts) and clinical outcome.

Methods: Our cohort included advanced TNBC pts unselected for family history or age at diagnosis, enrolled in an institutional molecular screening program (NCT01505400). DNA from matched blood and FFPE tumor samples was assessed using a lab developed next generation sequencing Hereditary Cancer Panel (NGS-HCP) that includes all exons of 52 cancer predisposition genes, with 20 HR genes (Illumina MiSeq/NextSeq, germline coverage 100x, somatic coverage 500x). Medical records were reviewed for clinical outcome, pathology and prior germline BRCA1/2 testing results. All pts consented for research on banked samples and return of pathogenic germline variants was optional. Log rank test was used to determine time from surgery with curative intent to relapse (TTR) and overall survival from diagnosis to death (OS) differences based on presence of HR variants.

Results: We included 32 pts who consented for return of pathogenic germline variants and had sufficient DNA for NGS-HCP analysis. Median age at diagnosis was 45 years (range 21-80). Initial stages at diagnosis were: I (12.5%), II (62.5%), III (19%) and IV (6%). Germline HR variants were detected in 17 pts (53%) with a median number of variants per patient of 1 (range 0-6). Five pts had likely pathogenic or pathogenic variants in HR genes: BRCA1 (2), BRCA2 (1) FANCC (1) and FANCC + BML (1). Another patient had a BRCA1 pathogenic variant previously detected by Multiplex Ligation-dependent Probe Amplification but was not detected by NGS-HCP. 26 variants of unknown significance (VUS) were identified in 13 HR genes, including FANCA (6), FANCF (3) and BRCA1 (3). Only one patient had a somatic HR variant in FANCA not found in the germline. 30 pts (94%) had somatic TP53 variants. Sporadic somatic BRCA1/2 variants were not seen. BRCA1/2 variants present in the tumor were equivalent to those detected in blood of BRCA1/2 carriers. Median (m) TTR was 17 months (range 1-119) and mOS was 49 months (range 8-123). Presence of likely pathogenic or pathogenic germline variants was not associated with TTR (p=0.78) and OS (p=0.23). Presence of germline VUS, likely pathogenic or pathogenic variants also did not correlate with TTR (p=0.72) and OS (p=0.47)

Conclusions: In our cohort of pts with advanced TNBC, 12% had germline pathogenic variants in BRCA1/2, similar to the previously reported rate in early stage TNBC pts. Prevalence of likely pathogenic or pathogenic variants in non-BRCA HR genes was 6%. The presence of germline variants in HR genes was not associated with clinical outcome, however, the number of patients included was small and we had limited power to detect survival differences.Background: Variants in homologous recombination (HR) genes other than BRCA1/2 may cause a BRCA-like phenotype triple negative breast cancer (TNBC), which includes the sensitivity to platinums and DNA repair inhibitors. Evaluation of HR proficiency may influence the clinical management of TNBC. Our aim was to evaluate germline and somatic HR gene variants in advanced TNBC patients (pts) and clinical outcome.

Methods: Our cohort included advanced TNBC pts unselected for family history or age at diagnosis, enrolled in an institutional molecular screening program (NCT01505400). DNA from matched blood and FFPE tumor samples was assessed using a lab developed next generation sequencing Hereditary Cancer Panel (NGS-HCP) that includes all exons of 52 cancer predisposition genes, with 20 HR genes (Illumina MiSeq/NextSeq, germline coverage 100x, somatic coverage 500x). Medical records were reviewed for clinical outcome, pathology and prior germline BRCA1/2 testing results. All pts consented for research on banked samples and return of pathogenic germline variants was optional. Log rank test was used to determine time from surgery with curative intent to relapse (TTR) and overall survival from diagnosis to death (OS) differences based on presence of HR variants.

Results: We included 32 pts who consented for return of pathogenic germline variants and had sufficient DNA for NGS-HCP analysis. Median age at diagnosis was 45 years (range 21-80). Initial stages at diagnosis were: I (12.5%), II (62.5%), III (19%) and IV (6%). Germline HR variants were detected in 17 pts (53%) with a median number of variants per patient of 1 (range 0-6). Five pts had likely pathogenic or pathogenic variants in HR genes: BRCA1 (2), BRCA2 (1) FANCC (1) and FANCC + BML (1). Another patient had a BRCA1 pathogenic variant previously detected by Multiplex Ligation-dependent Probe Amplification but was not detected by NGS-HCP. 26 variants of unknown significance (VUS) were identified in 13 HR genes, including FANCA (6), FANCF (3) and BRCA1 (3). Only one patient had a somatic HR variant in FANCA not found in the germline. 30 pts (94%) had somatic TP53 variants. Sporadic somatic BRCA1/2 variants were not seen. BRCA1/2 variants present in the tumor were equivalent to those detected in blood of BRCA1/2 carriers. Median (m) TTR was 17 months (range 1-119) and mOS was 49 months (range 8-123). Presence of likely pathogenic or pathogenic germline variants was not associated with TTR (p=0.78) and OS (p=0.23). Presence of germline VUS, likely pathogenic or pathogenic variants also did not correlate with TTR (p=0.72) and OS (p=0.47)

Conclusions: In our cohort of pts with advanced TNBC, 12% had germline pathogenic variants in BRCA1/2, similar to the previously reported rate in early stage TNBC pts. Prevalence of likely pathogenic or pathogenic variants in non-BRCA HR genes was 6%. The presence of germline variants in HR genes was not associated with clinical outcome, however, the number of patients included was small and we had limited power to detect survival differences.

Citation Format: Stjepanovic N, Kim RH, Wilson M, Mandilaras V, Berman H, Amir E, Cescon D, Elser C, Randall Armel S, McCuaig J, Volenik A, Demsky R, Chow H, Misyura M, Wang L, Oza AM, Kamel-Reid S, Stockley T, Bedard PL. Clinical outcome of patients with advanced triple negative breast cancer with germline and somatic variants in homologous recombination gene [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 P3-09-05.

The sooner the better: Genetic testing following ovarian cancer diagnosis

OBJECTIVE

As treatment based genetic testing becomes a reality, it is important to assess the attitudes and preferences of women newly diagnosed with ovarian cancer regarding genetic testing. The objective of this study was to determine when women with a diagnosis of high grade serous ovarian cancer would prefer to undergo genetic testing and factors that influence this preference.

METHODS

Women over 18years of age with a known diagnosis of high grade serous ovarian cancer diagnosed between October 2010-2013 were identified via the Princess Margaret Cancer Center Registry. Participants completed a questionnaire, which obtained preferences and attitudes towards genetic testing, cancer history, and demographic information.

RESULTS

120 of the 355 women identified (33.8%) completed the questionnaires. The median age at time of ovarian cancer diagnosis was 57years (range 35-84). The majority of participants in this study were offered (94.6%) and pursued (84.8%) genetic testing. In this cohort, testing was most frequently offered at diagnosis (41.8%) or during treatment (19.1%). In this study, women with high grade serous ovarian cancer felt that genetic testing should be offered before or at the time of diagnosis (67.8%). Having a family history of breast or ovarian cancer was significantly (p=0.012) associated with preferring genetic testing at an earlier time point in the disease course.

CONCLUSIONS

Our results demonstrate that women with high grade serous ovarian cancer acknowledge the personal and clinical utility of genetic testing and support test implementation at the time of cancer diagnosis.

Timing of oral contraceptive use and the risk of breast cancer in BRCA1 mutation carriers

It is not clear if early oral contraceptive use increases the risk of breast cancer among young women with a breast cancer susceptibility gene 1 (BRCA1) mutation. Given the benefit of oral contraceptives for the prevention of ovarian cancer, estimating age-specific risk ratios for oral contraceptive use and breast cancer is important. We conducted a case-control study of 2,492 matched pairs of women with a deleterious BRCA1 mutation. Breast cancer cases and unaffected controls were matched on year of birth and country of residence. Detailed information about oral contraceptive use was collected from a routinely administered questionnaire. Conditional logistic regression was used to estimate the odds ratios (OR) and 95 % confidence intervals (CI) for the association between oral contraceptive and breast cancer, by age at first use and by age at diagnosis. Among BRCA1 mutation carriers, oral contraceptive use was significantly associated with an increased risk of breast cancer for women who started the pill prior to age 20 (OR 1.45; 95 % CI 1.20-1.75; P = 0.0001) and possibly between ages 20 and 25 as well (OR 1.19; 95 % CI 0.99-1.42; P = 0.06). The effect was limited to breast cancers diagnosed before age 40 (OR 1.40; 95 % CI 1.14-1.70; P = 0.001); the risk of early-onset breast cancer increased by 11 % with each additional year of pill use when initiated prior to age 20 (OR 1.11; 95 % CI 1.03-1.20; P = 0.008). There was no observed increase for women diagnosed at or after the age of 40 (OR 0.97; 95 % CI 0.79-1.20; P = 0.81). Oral contraceptive use before age 25 increases the risk of early-onset breast cancer among women with a BRCA1 mutation and the risk increases with duration of use. Caution should be taken when advising women with a BRCA1 mutation to take an oral contraceptive prior to age 25.

Keeping it simple: genetics referrals for all invasive serous ovarian cancers

OBJECTIVE

In the province of Ontario, all women diagnosed with invasive serous ovarian cancer are eligible for genetic testing for mutations in the BRCA1 and BRCA2 genes. This study aimed to determine the proportion of these women who are seen for genetic counseling and to identify potential predictors and barriers to having genetic counseling.

METHODS

All women who were diagnosed with invasive serous ovarian cancer and had genetic counseling at Princess Margaret Hospital (PMH) between 2002 and 2009 were identified. Logistic regressions and trend analyses explored age at diagnosis, year at diagnosis, and the time between diagnosis and genetic counseling. Genetic counseling outcomes were also examined.

RESULTS

Of 623 women diagnosed with invasive serous ovarian cancer, 144 (23%) were seen for genetic counseling. As age at diagnosis increased, the likelihood of genetic counseling decreased (p=0.005). With a more recent date of diagnosis, the probability of having genetic counseling increased (p=0.032) while the time to genetic counseling decreased (p=0.001). Of women who pursued genetic testing, 31% were found to have a BRCA1 or BRCA2 mutation, 16% of whom had no family history of breast or ovarian cancer.

CONCLUSIONS

Despite the availability of genetic testing, only a small proportion of women with invasive serous ovarian cancer were seen for genetic counseling. Over time, an improvement in the proportion of women being seen for genetic counseling was noted; however barriers to seeing women with a later age at diagnosis or those with no family history of breast or ovarian cancer clearly exist.

The effectiveness of family history questionnaires in cancer genetic counseling

The number of individuals receiving genetic counseling for hereditary breast and ovarian cancer syndrome has steadily risen. To triage patients for genetic counseling and to help reduce the amount of time needed by a genetic counselor in direct patient contact, many clinics have implemented the use of family history questionnaires. Although such questionnaires are widely used, scant literature exists evaluating their effectiveness. This article explores the extent to which family history questionnaires are being used in Ontario and addresses the utility of such questionnaires in one familial cancer clinic. By comparing the pedigrees created from questionnaires to those updated during genetic counseling, the accuracy and effectiveness of the questionnaires was explored. Of 121 families recruited into the study, 12% acquired changes to their pedigree that led to a revised probability estimate for having a BRCA1 or BRCA2 mutation and 5% acquired changes that altered their eligibility for genetic testing. No statistically significant difference existed between the eligibility for genetic testing prior to and post counseling. This suggests that family history questionnaires can be effective at obtaining a family history and accurately assessing eligibility for genetic testing. Based on the variables that were significantly associated with a change in probability estimate, we further present recommendations for improving the clarity of such questionnaires and therefore the ease of use by patients.

Differential activation of protein kinase B and p70(S6)K by glucose and insulin-like growth factor 1 in pancreatic beta-cells (INS-1)

It has been shown that IGF-1-induced pancreatic beta-cell proliferation is glucose-dependent; however, the mechanisms responsible for this glucose dependence are not known. Adenoviral mediated expression of constitutively active phosphatidylinositol 3-kinase (PI3K) in the pancreatic beta-cells, INS-1, suggested that PI3K was not necessary for glucose-induced beta-cell proliferation but was required for IGF-1-induced mitogenesis. Examination of the signaling components downstream of PI3K, 3-phosphoinositide-dependent kinase 1, protein kinase B (PKB), glycogen synthase kinase-3, and p70-kDa-S6-kinase (p70(S6K)), suggested that a major part of glucose-dependent beta-cell proliferation requires activation of mammalian target of rapamycin/p70(S6K), independent of phosphoinositide-dependent kinase 1/PKB activation. Adenoviral expression of the kinase-dead form of PKB in INS-1 cells decreased IGF-1-induced beta-cell proliferation. However, a surprisingly similar decrease was also observed in adenoviral wild type and constitutively active PKB-infected cells. Upon analysis of extracellular signal-regulated protein kinase 1 and 2 (ERK1/ERK2), an increase in ERK1/ERK2 phosphorylation activation by glucose and IGF-1 was observed in kinase-dead PKB-infected cells, but this phosphorylation activation was inhibited in the constitutively active PKB-infected cells. Hence, there is a requirement for the activation of both ERK1/ERK2 and mammalian target of rapamycin/p70(S6K) signal transduction pathways for a full commitment to glucose-induced pancreatic beta-cell mitogenesis. However, for IGF-1-induced activation, these pathways must be carefully balanced, because chronic activation of one (PI3K/PKB) can lead to dampening of the other (ERK1/2), reducing the mitogenic response.

Sequencing and expression analysis of the serine protease gene cluster located in chromosome 19q13 region

The human kallikrein gene cluster, located in the chromosome band 19q13, contains several tissue-specific serine protease genes including the prostate-specific KLK2, KLK3 and prostase genes. To further characterize the gene cluster, we have mapped, sequenced, and analyzed the genomic sequence from the region. The results of EST database searches and GENSCAN gene prediction analysis reveal 13 serine protease genes and several pseudogenes in the region. Expression analysis by RT-PCR indicates that most of these protease genes are expressed only in a subset of the 35 different normal tissues that have been examined. Several protease genes expressed in skin show higher expression levels in psoriatic lesion samples than in non-lesional skin samples from the same patient. This suggests that the imbalance of a complex protease cascade in skin may contribute to the pathology of disease. The proteases, excluding the kallikrein genes, share approximately 40% of their sequences suggesting that the serine protease gene cluster on chromosome 19q13 arose from ancient gene duplications.