Abstract GS6-06: A neoadjuvant trial with letrozole identifies PRR11 in the 17q23 amplicon as a mechanism of resistance to endocrine therapy in ER-positive breast cancer

Although the 17q23 amplicon has been associated with luminal B breast cancer (BC) and high risk of recurrence, a specific gene or genes in this region that would be causal to endocrine resistance have not yet been uncovered. We performed whole transcriptome analysis on RNA extracted from 58 estrogen receptor (ER)+ BCs treated with neoadjuvant letrozole for median 7.2 months. PRR11 (Proline rich 11), located in 17q23, was upregulated in non-responding tumors as defined by relapse after a median follow up of 5 years and/or a preoperative endocrine prognostic index (PEPI) ≥4. Differential gene expression analysis between tumors expressing low vs high PRR11 mRNA showed that BC signatures associated with proliferation, IGF-1 and PI3K signaling were enriched in tumors with high PRR11 expression.

Rate of PRR11 amplification is 15.2% in the Metastatic Breast Cancer project, but 9.5% and 9.4% in METABRIC and The Cancer Genome Atlas (TCGA), respectively. Gene Set Enrichment Analysis revealed an enrichment of hallmark gene sets associated with proliferation in PRR11-amplified ER+ BCs in METABRIC and TCGA. Integrated analysis of gene expression with on-treatment Ki67 levels from three independent studies with operable ER+ BCs treated with neoadjuvant aromatase inhibitor (ACOSOG-Z1031, NCT00651976, Llombart-Cussac et al.) showed that PRR11 was the only gene in 17q23 with a significant correlation with a high Ki67 levels across all studies.

PRR11 knockdown inhibited E2-independent growth of HCC1428 LTED (long-term estrogen deprived) and MCF7 LTED cells in culture and MCF7 xenografts. PRR11 siRNA also inhibited growth of fulvestrant-resistant and tamoxifen-resistant MCF7 cells. Conversely, PRR11 transduction induced MDA-MB-134VI cell growth under estrogen-depleted conditions. Using a PCR array with 84-cell cycle genes, we identified SKP2, CDKN1A, CCNB2, CCNA2, CKS2 and CCNB1 as genes downregulated by PRR11 knockdown. Except for SKP2 and CDKN1A, expression of all those genes was elevated in PRR11-amplifiedER+ BCs in TCGA and METABRIC.

Suggesting a link to activation of PI3K signaling, we found the proline-rich motif of PRR11 associates with the SH3 domain of the p85 regulatory subunit of PI3K. We hypothesized that this association suppresses p85 homodimer formation, thus facilitating binding of PI3Kα (p110α)-p85 dimers to IRS1, retention of p110α at the plasma membrane and, hence, activation of PI3K/AKT. To test this, we co-transfected HEK293T cells with HA-p85 and FLAG-p85. Forced expression of PRR11 reduced HA-p85 and FLAG-p85 homodimers as shown by HA and FLAG pulldowns followed by FLAG and HA immunoblots, respectively. PRR11 overexpression enhanced insulin-stimulated association of IRS1 to p110α and activation of AKT. PRR11 knockdown reduced insulin/IGF-1/2-stimulated p-AKT. In METABRIC and TCGA, PRR11 amplification and PIK3CA mutations are exclusive of each other, suggesting these alterations would be functionally linked with the same pathway.

Connectivity map analysis with the list of genes significantly overexpressed in ER+/PRR11-amplified BCs predicted PI3K inhibitors as perturbations that suppress such gene list. In the MGH/Sanger dataset, PRR11-amplified BC cell lines displayed significantly higher sensitivity to the pan-PI3K inhibitor pictilisib compared to cell lines without PRR11 amplification. Finally, inhibition of PI3Kα by siRNA or alpelisib abrogated E2-independent growth and insulin-stimulated growth of PRR11-transduced MDA-MB-134VI and MCF10A cells, respectively, suggesting p110α is required for the growth promoting effects of PRR11.

These data suggest that 1) PRR11 is a mediator of resistance to antiestrogens via amplification of PI3K/AKT signaling, and 2) PI3Kα is a potential therapeutic target in ER+ BCs harboring PRR11 amplification.

Citation Format: Kyung-min Lee, Angel Guerrero-Zotano, Ariella Hanker, Alberto Servetto, Dhivya Sudhan, Luigi Formisano, Valerie Jansen, Paula González-Ericsson, Melinda Sanders, Thomas Stricker, Lewis Cantley, Carlos Arteaga. A neoadjuvant trial with letrozole identifies PRR11 in the 17q23 amplicon as a mechanism of resistance to endocrine therapy in ER-positive breast cancer [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr GS6-06.

Abstract PD2-09: The genomic landscape of intrinsic and acquired resistance to cyclin-dependent kinase 4/6 inhibitors (CDK4/6i) in patients with hormone receptor-positive (HR+)/HER2- metastatic breast cancer (MBC)

Background: The CDK4/6 inhibitors have emerged as standard first- or second-line regimens in combination with an antiestrogen for patients with HR+/HER2- MBC. While these agents convey significant clinical benefit in many patients, intrinsic resistance can occur and, in patients who respond, acquired resistance is unfortunately inevitable. Despite their widespread use, we have limited insight into the molecular mechanisms governing response and resistance to these agents.

Methods: Whole exome sequencing (WES) was performed on metastatic tumor biopsies from 58 patients (pts) with HR+/HER2- MBC who received a CDK4/6 inhibitor with or without an antiestrogen at the Dana-Farber Cancer Institute, including 7 pts with pre/post-exposure biopsy pairs. Among these biopsies, 69.5% were characterized as resistant (intrinsic or acquired) and 30.5% were characterized as sensitive. To validate putative resistance mediators identified in patient samples, HR+/HER2- breast cancer cells were modified via CRISPR knockout or lentiviral overexpression. Sensitivity of these cells to antiestrogens and CDK4/6i was interrogated via cell-titer-glo assay. In parallel, HR+/HER2- breast cancer cells were cultured to resistance in the presence of an escalating dose of CDK4/6i. Derivative cell lines were subjected to western blotting in an effort to interrogate the putative resistance mediators identified in pts. Novel dependencies were identified in these derivative cell lines via treatment with targeted therapeutic agents in vitro.

Results: WES of tumors with CDK4/6i exposure revealed candidate mechanisms of resistance including biallelic RB1 disruption (n=4, 10%) and activating events in AKT1 (n=5, 12.5%), RAS (n=4, 10%), aurora kinase A (AURKA, n=11, 27.5%), and cyclin E2 (CCNE2, n=6, 15%). Convergent evolution toward biallelic RB1 disruption was identified in a single patient with one pre- and two post-exposure biopsies, while acquisition of AKT1 mutation and amplification was identified in two separate instances. Knockout of RB1 and overexpression of AKT1, KRAS G12D, AURKA, and CCNE2 provoked CDK4/6i and antiestrogen resistance in vitro. Breast cancer cells cultured to resistance in CDK4/6i demonstrated concordant acquisition of RB1 downregulation, RAS/ERK activation, AURKA overexpression, and CCNE2 overexpression. Derivative resistant cell lines with RB1 loss or AURKA gain demonstrated enhanced sensitivity to a novel AURKA inhibitor (LY3295668), while cells with RAS activation were highly sensitive to ERK inhibition (via LY3214996). CCNE2-overexpressing cells were highly sensitive to prexasertib, a CHEK1 inhibitor.

Conclusions: The genomic landscape of resistance to CDK4/6i is heterogeneous with multiple potential mediators that play well-established roles in cell division and oncogenic signal transduction. We present novel mechanisms of clinical resistance including activation of AKT1 and RAS family oncogenes as well as amplification of AURKA and CCNE2. These drivers were able to provoke resistance to CDK4/6i in vitro. Finally, in each case, a novel dependency was identified which is readily translatable into the clinic. These results underscore the potential of next-generation sequencing as a critical tool to enable identification of resistance mediators, while also suggesting that the presence of specific genomic alterations may define new therapeutic opportunities in CDK4/6i-resistant HR+ MBC.

Citation Format: Seth A. Wander, Ofir Cohen, Xueqian Gong, Gabriela N. Johnson, Jorge Buendia-Buendia, Maxwell Lloyd, Dewey Kim, Flora Luo, Pingping Mao, Karla Helvie, Kailey Kowalski, Utthara Nayar, Stephen Parsons, Ricardo Martinez, Lacey Litchfield, Xiang Ye, Chun Ping Yu, Valerie Jansen, Levi A. Garraway, Eric P. Winer, Sara M. Tolaney, Nancy U. Lin, Sean Buchanan, Nikhil Wagle. The genomic landscape of intrinsic and acquired resistance to cyclin-dependent kinase 4/6 inhibitors (CDK4/6i) in patients with hormone receptor-positive (HR+)/HER2- metastatic breast cancer (MBC) [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr PD2-09.

Abstract P3-08-15: Immunologic correlates of long-term outcome in the residual disease of triple-negative breast cancer after neoadjuvant chemotherapy

The recent approval of anti-PD-L1 immunotherapy in combination with nAB-paclitaxel for metastatic triple-negative breast cancer (TNBC) highlights the need to understand the role of chemotherapy in modulating the tumor-immune microenvironment (TIME). Patients with TNBC are routinely treated with neoadjuvant chemotherapy (NAC). Stromal tumor-infiltrating lymphocytes (sTILs) in the pre-treatment diagnostic biopsy are predictive of pathologic complete response (pCR). In patients with residual disease (RD) at surgery, sTILs confer good prognosis. However, the effect of chemotherapy on sTILs and how it influences the TIME are poorly understood. We examined immune-gene expression patterns before and after NAC in a series of 83 breast tumors, including 44 TNBCs, from patients with RD. sTILs were enumerated by standardized guidelines. Gene expression patterns were tested for association with recurrence-free (RFS) and overall survival (OS). T cell receptor sequencing (TCRseq) was performed on a subset (n=15) of tumors. In 4 patients undergoing NAC, PD-1-high and -negative CD8+ peripheral blood mononuclear cells (PBMCs) were profiled using single-cell RNAseq and multiplexed cytokine secretion assays. Post-NAC sTILs (≥30%) were only predictive of outcome (RFS p=0.019; OS p=0.05) in TNBC patients, but not in non-TNBC patients (RFS p=0.28; OS p=0.78) confirming that the prognostic capacity of sTILs is confined to TNBC. Pre-NAC sTILs were not predictive of outcome in either group, likely due to exclusion of patients experiencing pCR. The change in sTILs during NAC did not prognosticate outcome in TNBC, suggesting that in the post-NAC setting, only the most proximal measurement of sTILs is meaningful. However, these results did suggest that NAC alters the TIME. To examine the interplay among NAC, the TIME, and clinical outcomes, we tested the change in expression of 770 immune-related genes during NAC in univariate cox-proportional hazards models. In non-TNBC, no change in expression of any single gene was associated with RFS or OS at a false-discovery rate (FDR) of 10%. In TNBC, individual changes in 12 genes and 204 genes were identified as associated with RFS and OS, respectively (FDR<10%). Interestingly, in nearly all cases, upregulation of these genes during NAC was associated with improved outcome, with only 1 and 15 genes being associated with poor RFS and OS, respectively. Collapsing genes to functional and cell-type specific signatures gave similar insights: T cell, NK cell, TNF-superfamily, and toll-like receptor signatures were highly prognostic. Surprisingly, NAC did not alter T cell clonality in TNBC. Thus, the immunologic impact of chemotherapy appears to be specific to TNBC and is primarily a beneficial effect but does not appear to appreciably expand the clonality of tumor-infiltrating T cells. Using fresh PD-1HI CD8+ T cells isolated from PBMCs of patients undergoing NAC, we detected a significant increase in cytolytic and inflammatory cytokines secreted in 2 TNBC patients after chemotherapy, but not in 2 non-TNBC patients, which was particularly dramatic in one TNBC patient who experienced a pCR. A further characterization of PD-1HI CD8+ cells by single-cell RNAseq identified a sizeable expansion of cytolytic gene (granulysin, Ksp37, granzyme) expressing cells in the TNBC patient with pCR compared to the TNBC patient with RD. In conclusion, we have characterized the effects of NAC on the TIME. TNBC appears to be uniquely sensitive to the immunologic effects of NAC, and most of these effects are primarily stimulatory, rather than repressive. Finally, these changes can be observed in the PD-1HI CD8+ peripheral T cell compartment and appeared to co-occur with pCR.

Citation Format: Justin M Balko, Mellissa Nixon, Paula I Gonzalez-Ericsson, Mark A Pilkinton, Wyatt J McDonnell, Violeta Sanchez, Susan R Opalenik, Sherene Loi, Brent Rexer, Vandana Abramson, Valerie Jansen, Simon Mallal, Jonathan D Marotti, Kevin Shee, Todd W Miller, Melinda E Sanders, Ingrid A Mayer, Roberto Salgado. Immunologic correlates of long-term outcome in the residual disease of triple-negative breast cancer after neoadjuvant chemotherapy [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P3-08-15.

Abstract PD2-10: Treatment with abemaciclib modulates the immune response in gene expression analysis of the neoMONARCH neoadjuvant study of abemaciclib in postmenopausal women with HR+, HER2 negative breast cancer

Background: Abemaciclib is a selective inhibitor of CDK4 & 6 approved on a continuous dosing schedule for the treatment of HR+, HER2- metastatic breast cancer (MBC) patients (pts) in combination with endocrine therapy or as monotherapy. Recent studies have demonstrated the potential for CDK4 & 6 inhibitors, including abemaciclib, to promote anti-tumor immunity. Schaer et al., (Cell Reports 2018) showed that abemaciclib monotherapy results in upregulation of antigen presentation on tumor cells and increases T-cell activation. These activities synergized with anti-PD-L1 therapy to further enhance immune activation leading to complete tumor rejection in murine tumor models (Schaer et al., Cell Reports 2018). In this exploratory analysis, we evaluated the early and late immune-modulating effects of abemaciclib in the neoadjuvant study neoMONARCH (NCT02441946).

Methods: NeoMONARCH is a Phase II trial in women with stage I-IIIB HR+, HER2- BC evaluating neoadjuvant treatment with 2 weeks of abemaciclib, alone or in combination with anastrozole (abemaciclib+ANZ), or ANZ alone. All patients received 14 weeks of abemaciclib +ANZ after the first 2 weeks of treatment. Serial biopsies were collected at 3 time points: Baseline (BL) - prior to treatment, Early - after 2 weeks of therapy with abemaciclib, ANZ, or abemaciclib+ANZ, and Late – after 2 weeks of initial therapy followed by 14 weeks of abemaciclib+ANZ. RNA was extracted from formalin fixed paraffin embedded (FFPE) tumor biopsies at each time point and subjected to whole transcriptome RNA sequencing. The curated data were subjected to statistical analysis using ANOVA tests followed by pathway analysis using Ingenuity Pathway Analysis (IPA) and Gene Set Enrichment Analysis (GSEA).

Results: Consistent with the known activity of abemaciclib to inhibit the cell cycle, we observed at the early and late time points a significant treatment induced downregulation of genes related to mitotic spindle organization, replication stress response, G2M checkpoint, and E2F targets. Abemaciclib treatment for 2 weeks, alone or in combination with ANZ, followed by 14 weeks of combination therapy was associated with upregulation of gene expression signatures related to T-cell immune response and antigen presentation. Importantly, this phenomenon was notobserved with 2 weeks of ANZ treatment alone followed by 14 weeks of combination therapy.

Conclusion: These data lend support that continuous inhibition of CDK4 & 6 signaling by abemaciclib treatment leads to prolonged cell cycle arrest resulting in tumor cell apoptosis & senescence, which then leads to an enhanced immune activation.

Citation Format: Hurvitz S, Martin M, Press M, Wijayawardana S, Brahmachary M, Ebert PJ, Young S, Jansen V, Slamon D. Treatment with abemaciclib modulates the immune response in gene expression analysis of the neoMONARCH neoadjuvant study of abemaciclib in postmenopausal women with HR+, HER2 negative breast cancer [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr PD2-10.

Abstract PD7-10: Neoadjuvant trial with letrozole identifies PRR11 in 17q21-23 amplicon as a resistance mechanism to endocrine therapy in ER-positive breast cancer

Approximately 20% of patients with early ER+ breast cancer (BC) treated with adjuvant antiestrogen therapy relapse with metastatic disease. Previously, we identified 3 amplicons (11q11.3, 8p11.23, and 17q21-23) associated with endocrine-resistance (Giltnane et al. Sci Transl Med 2017). The 17q21-23 amplicon has been associated with highly proliferative luminal B tumors and cancers with high genomic instability. A causal role of this region in endocrine resistance is unclear. We performed whole transcriptome analysis on RNA extracted from 58 ER+ breast cancers of patients treated with letrozole for 5.4-9.2 months (median 7.2 months). PRR11 (Proline rich 11), located in 17q21-23, was significantly upregulated in non-responding tumors as defined by cancer relapse after a median follow up of 5 years and/or a preoperative endocrine prognostic index (PEPI) ≥4. Differential gene expression analysis between tumors expressing low vs high PRR11 mRNA showed that BC signatures associated with proliferation, cell cycle, IGF-1 and PI3K signaling were enriched in tumors with high PRR11 expression. In the Metastatic Breast Cancer Project and TCGA, PRR11 amplification was higher in metastatic vs. primary BCs (16.5% and 8.5%, respectively; Fisher's p=0.0088). Gene Set Enrichment Analysis of mRNA expression in METABRIC and TCGA revealed significant enrichment of hallmark gene sets associated with proliferation in PRR11 amplified ER+ BCs. Genome-scale RNAi screening in Project Achilles showed that among all genes in the 17q21-23 amplicon, PRR11 knockdown results in the 4th strongest anti-proliferative effect in MCF7 cells. PRR11 knockdown with siRNA inhibited proliferation, cell cycle progression, and RB phosphorylation in HCC1428 LTED (long-term estrogen deprived), MCF7 LTED, and fulvestrant-resistant MCF7 cells. Using a PCR array with 84-cell cycle genes, we identified SKP2, CDKN1A, CCNB2, CCNA2, CKS2 and CCNB1 as genes downregulated by PRR11 knockdown. Except for CDKN1A, expression of all those genes was elevated ER+ BCs with PRR11 gain or amplification in TCGA. PRR11 associates with the p85 regulatory subunit of PI3K via its SH3 domain. We speculated this association would suppress p85 homodimers, thus permitting binding of PI3Kα (p110α)-p85 dimers to IRS1 and, hence, activating PI3K/AKT. To test this, we co-transfected HEK293T cells with HA-p85 and FLAG-p85. Transfection of PRR11 into these HEK293T cells reduced HA-p85 and FLAG-p85 homodimers as shown by HA and FLAG pulldowns followed by FLAG and HA immunoblots, respectively. Finally, PRR11 knockdown resulted in a reduction of p110a and S473 P-AKT levels and inhibition of IGF-1/2 stimulated P-AKT. Not inconsistent with these data, PRR11 amplification and PIK3CA mutations in METABRIC and TCGA are exclusive of each other, suggesting these alterations are functionally linked with the same signaling pathway. These data support a role of PRR11 in PI3K/AKT activation that may be causal to resistance to estrogen deprivation. We propose PRR11, located in the 17q21-23 amplicon, is a potential mediator of resistance to antiestrogen therapy by amplifying PI3K/AKT signaling, suggesting PI3K may be a therapeutic target in ER+ BCs harboring PRR11 amplification.

Citation Format: Lee K-M, Guerrero-Zotano A, Formisano L, Jansen V, Gonzalez Ericsson P, Arteaga C. Neoadjuvant trial with letrozole identifies PRR11 in 17q21-23 amplicon as a resistance mechanism to endocrine therapy in ER-positive breast cancer [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr PD7-10.

Abstract P3-10-08: Markers of response to CDK4 & 6 inhibition from neoMONARCH: A phase II neoadjuvant study of abemaciclib in postmenopausal women with hormone receptor positive, HER2 negative breast cancer

Background: Combination treatments of endocrine therapy (ET) with CDK4 & 6 inhibitors have improved outcomes in patients with HR+ advanced breast cancer, both as initial therapy and after progression on ET. Abemaciclib is a selective inhibitor of CDK4 & 6 approved on a continuous dosing schedule for the treatment of HR+, HER2- MBC patients (pts), alone or in combination with ET. However, biomarkers that predict benefit from this class of agents remain elusive. We previously reported in the phase II neoadjuvant neoMONARCH study (NCT02441946), after 2 weeks of treatment, abemaciclib, alone or in combination with anastrozole (ANZ), led to a significantly higher rate of complete cell cycle arrest (CCCA, defined as Ki67 ≤2.7%) compared to ANZ alone in early stage HR+, HER2- breast cancer (Martin et al. SABCS 2017). As an exploratory aim of this trial, we evaluated the gene expression analyses in order to determine markers of sensitivity and resistance to therapy.

Methods: Serial biopsies were collected at 3 time points: Baseline (BL) - prior to treatment, Early – after 2 weeks of therapy with abemaciclib, ANZ, or abemaciclib+ANZ, and Late – after 2 weeks of initial therapy followed by 14 weeks of abemaciclib+ANZ. RNA was extracted from FFPE tumor biopsies at each timepoint and subjected to a Cell Cycle Associated Gene (CCAG) expression panel using the Modaplex® platform and whole transcriptome RNA sequencing. Ki67 was measured at each time point by immunohistochemistry (IHC). Tumors were categorized by the post-treatment Ki67 expression as either sensitive (Ki67 ≤2.7) or resistant (Ki67 ≥7.4), based upon the IMPACT and POETIC studies. Additionally, tumors intrinsically resistant/sensitive to therapy were also identified.

Results: ANZ-treated tumors that did not achieve CCCA at 2 weeks (N= 8) displayed higher expression of the cell cycle associated genes FOXM1, E2F1, TOPO2A, and RRM2. The addition of abemaciclib to ANZ decreased gene expression in a majority of the tumors (N=5, 62.5%). Tumors intrinsically resistant to treatment with abemaciclib+ANZ displayed persistently elevated levels of cell cycle associated genes compared to sensitive tumors. Finally, gene expression signature of Rb loss-of-function (Rbsig) and RB1 gene expression levels were associated with sensitivity to abemaciclib.

Conclusion: On-treatment Ki67 indicated treatment sensitivity and correlated with cell cycle associated gene expression in sensitive and resistant tumors. These exploratory analyses suggest that gene expression analyses may identify genomic markers for abemaciclib and ET treatment sensitivity and may help inform in which tumors to use abemaciclib.

Citation Format: Hurvitz S, Martin M, Wijayawardana S, Brahmachary M, Ebert PJ, Young S, Jansen V, Slamon D. Markers of response to CDK4 & 6 inhibition from neoMONARCH: A phase II neoadjuvant study of abemaciclib in postmenopausal women with hormone receptor positive, HER2 negative breast cancer [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P3-10-08.

Abstract 1945: TORC inhibitors increase the cancer stem cell (CSC) population and Notch signaling in triple negative breast cancer

Tumor-initiating cells (TICs) or cancer stem cells (CSCs) are resistant to chemotherapy and have been associated with metastatic recurrences and poor patient outcome particularly among patients with triple negative breast cancer (TNBC). Genomic and proteomic data have indicated more than 30% of TNBC patients have PI3K/mTOR pathway lesions making this pathway a promising therapeutic target. Recent publications have demonstrated mechanisms of resistance (JAK2/STAT5 and MYC amplification) to PI3K pathway inhibitors. We hypothesized that resistance to TORC inhibition is due to the survival of a CSC population and that targeting pathways that sustain these cells can provide a significant therapeutic benefit. Treatment of TNBC cell lines with the PI3K/mTOR inhibitor NVP-BEZ235 or the TORC1/2 inhibitor MLN128 resulted in a significant reduction of proliferation in vitro. However, we observed that both BEZ235 and MLN128 enriched for a CSC population as assessed by FACS analysis of cancer stem-like markers and mammosphere formation. This observation was specific to TNBC cell lines since BEZ235 and MLN128 significantly abrogated the CSC population in ER+ (MCF7) and HER2+ (HCC1954) breast cancer cell lines. To determine the mechanisms involved in this CSC enrichment we used a Stem Cell specific PCR Array. We observed an increase in Notch1, FGF1 and ABCG2 mRNA levels in TNBC cells treated with BEZ235 and MLN128. Treatment with these inhibitors also increased the expression of the active Notch intracellular domain, the Notch ligand Jagged1, and the Notch1 target genes Hes1 and Hey1 by qRT-PCR and transcriptional reporter activity. In addition to Hes1 and Hey1, c-myc, another Notch target gene, expression was augmented in 2 of the 3 TNBC cell lines tested. Treament with the γ-secretase inhibitor, DAPT and transfection with Notch1 siRNA oligonucleotides abrogated BEZ235 and INK128-mediated enrichment of CSC populations as measured by FACS analysis and mammosphere formation assays. To determine whether inhibition of either TORC1 or TORC2 enriched for the CSC population, we used RNAi against Rictor (TORC2), Raptor (TORC2) or both. We observed that only the combined knockdown of Rictor and raptor increased the CSC population in TNBC cell lines.

These observations suggest that treatment of TNBC harboring PI3K pathway aberrations with TORC1/2 inhibitors results in an initial reduction of tumor burden but do not eradicate the drug-resistant, slow cycling CSC population driven by Notch signaling. Thus, combination of a Notch inhibitor with TORC1/2 inhibitors and chemotherapy may be an effective therapeutic strategy to decrease primary tumor growth and prevent recurrences in patients with TNBC.

Citation Format: Neil E. Bhola, Valerie Jansen, Carlos Arteaga. TORC inhibitors increase the cancer stem cell (CSC) population and Notch signaling in triple negative breast cancer. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1945. doi:10.1158/1538-7445.AM2014-1945

WRIST DENERVATION IN ISOLATION: A PROSPECTIVE OUTCOME STUDY WITH PATIENT SELECTION BY WRIST BLOCKADE

Surgical wrist denervation involves division of the anterior and posterior interosseous nerves and articular branches of the superficial radial nerve. In this outcome study, 37 patients were individually assessed and deemed suitable for denervation surgery due to appreciable symptom resolution following a local anesthetic wrist block. At a mean of 18 months following denervation surgery, median activity pain scores had decreased by 60% (p < 0.001) from initial assessment levels, and more than three quarters (30/37) of patients reported continued improvement in their activity pain (p < 0.001). More than two thirds of patients had a satisfaction VAS of greater than 50, with less postoperative resting pain and a greater reduction in postoperative activity pain as the important predictors of patient satisfaction. Thirty-one out of the 37 patients had not represented to our department for revision wrist surgery by a mean of 10.3 years follow-up. We have found this procedure useful in ameliorating symptoms for some patients who would conventionally have required partial or total wrist fusions with greater residual functional limitation.

[Plasma concentration of endothelin-1 after myocutaneous latissimus dorsi-transplantation -- role in reperfusion injury]

The success of a free flap transplantation is based on a sufficient microanastomosis which meets the following requirements: a pedicle placed without kinking or twisting, a good drainage, a well defined recipient vessel and integrity of the endothelium. The aim of this study was to determine whether operation-related ischaemia through flap transplantation and tourniquet induces an increase of Endothelin-1 plasma levels as one cause of vasospasm during microvascular procedures. We focused our attention in particular on the reperfusion period which is often limited to an irreversible perfusion failure of microcirculation due to free radicals, interleukin and Endothelin-1. Twenty-one patients with tissue injury of the lower leg were included in our study, fourteen underwent a latissimus dorsi muscle transplantation with a combined ischaemia, seven patients had a tourniquet ischaemia for tumour resection, debridement and local flap transfer. The duration of ischaemia varied due to the course of operation. The withdrawal of venous blood via central vein catheter, flap vein and wound bed followed a fixed time table pre- and post-reperfusion (T1: preoperative day via cubital vein, T2: 6th postoperative day, T3: 5 min, T4: 10 min, T5: 15 min, T6: 1 h post-declamping and after tourniquet ischaemia via central vein catheter and T7: within 5 min from the flap vein immediate after recharging the flap). The vessel anastomosis determined the withdrawal from the local wound bed. ET-1 in venous blood samples were measured with ELISA. The duration of ischaemia in the tourniquet group ranged from 22 min up to 210 min with a mean of 76.58 min and in the latissimus group from 87 min up to 203 min with a mean of 139.21 min. The mean ET-1 plasma concentration measured systemically before operation in the 21 patients was 0.51 +/- 0.08 pg/ml (Mean +/- SD). This result corresponds with data published in literature. The locally measured plasma levels of ET-1 after tourniquet and flap ischaemia were increased with 0.34 up to 3.90 pg/ml (0.95 +/- 0.79 pg/ml [Mean +/- SD]) for the tourniquet group and with 0.34 up to 14.87 pg/ml (1.85 +/- 3.64 pg/ml [Mean +/- SD]) for the latissimus group. This is an increase compared to systemically measured values as 0.75 +/- 0.06 pg/ml (Mean +/- SD) for the tourniquet group and 0.58 +/- 0.21 pg/ml (Mean +/- SD) for the latissimus group. We conclude that Endothelin-1 is increased locally in the early reperfusion period after free latissimus dorsi-transplantation.

A stop codon mutation in COL11A2 induces exon skipping and leads to non-ocular Stickler syndrome

Mutations in COL11A2 cause a spectrum of phenotypes affecting chondrogenic tissues. We analyzed this gene by conformation sensitive gel electrophoresis (CSGE) and sequencing in a family with non-ocular Stickler syndrome, and found a heterozygous C --> T mutation in exon 57 + 13 in affected members, resulting in Arg893Stop codon. Since heterozygous nonsense mutations in COL11A2 do not usually lead to any obvious phenotype, all exons and exon boundaries of COL11A2 in the sample of the propositus were sequenced. Because no disease-associated alterations were found, we performed RT-PCR analysis on the RNA. Analysis showed skipping of exon 57 in one allele, resulting in an inframe deletion of 54 bp or 18 amino acids, which would explain the phenotype observed in the family. Thus, the exon skipping resulted from a nonsense-associated altered splicing (NAS). This article contains supplementary material, which may be viewed at the American Journal of Medical Genetics website at http://www.interscience.wiley.com/jpages/0148-7299/suppmat/index.html.

[The use of regional anesthesia in orthopedics]

Regional anesthesia has its place in the perioperative pain management of orthopedic patients. A reduction in postoperative mortality and morbidity with regional anesthesia is acknowledged for subsets of patient populations. Single shot and continuous applications are techniques for providing regional analgesia. Continuous infusion of local anesthetics with catheter techniques provides for uninterrupted postoperative analgesia. The combination of regional and general anesthesia reduces the consumption of systemic anesthetics. The side effects of opioid therapy are thereby reduced. The inhibition of intraoperative stress reaction, especially with epidural anesthesia, helps to prevent or lower unwanted metabolic changes. Patient contentment with analgesic quality differs with the technique with which the regional anesthesia is applied (PDA, PCEA, IVRA, peripheral block, i.a. injection), and the medication (LA, opioid) used.

Carrier screening for Gaucher disease in couples of mixed ethnicity

With the advent of mutational analysis for Gaucher disease, carrier screening has been incorporated into many Jewish genetic disease screening programs. Frequencies and mutations for Gaucher disease in non-Jewish populations are less well established and the detection rate of carriers are lower. Testing is problematic for resolving residual risk in a couple of mixed ethnicity. We report the testing choices made by 20 consecutive couples of mixed ethnicity where the Ashkenazi Jewish partner was identified to be a Gaucher disease gene carrier. Carrier studies of the non-Jewish partner were elected as follows: DNA studies alone, 5 (25%); enzymatic assay, 2 (10%); both, 6 (30%); no carrier studies, 7 (35%). Of the 7 couples not electing carrier studies, one was not in a pregnancy and 6 elected prenatal diagnosis in lieu of parental testing by enzymatic analysis of amniocytes. One couple elected parental carrier studies as well as prenatal diagnosis. All couples electing prenatal Gaucher determination had amniocentesis for other indications as well (4, advanced maternal age; 4, parental anxiety). We conclude that Gaucher screening is feasible for couples of mixed ethnicity if appropriate counseling and testing are offered.

Systemic levels contribute significantly to increased intraocular IGF-I, IGF-II and IGF-BP3 [correction of IFG-BP3] in proliferative diabetic retinopathy

Increased intraocular levels of angiogenic growth factors such as insulin-like growth factor I (IGF-I) have been demonstrated in proliferative diabetic retinopathy (PDR). It is unclear whether increased leakage of the blood retina barrier or local synthesis primarily determine intraocular levels of IGFs in man, which is of special interest regarding possible therapeutic options with somatostatin analogues in PDR. This is the first study investigating parallelly serum and vitreous levels of IGF-I/II, IGF-BP3 and the liver-derived permeability marker albumin to determine in vivo the amount of circulation-derived intraocular IGFs. A control group without retinal proliferation and patients with PDR were compared. Levels of IGF-I/II, IGF-BP3 and albumin were determined by immunological methods. Vitreous levels of albumin were 2.2-fold elevated in patients with PDR (254.1 +/- 37.2mg/dl; n = 27; p = 0.0027) compared to controls (115.7 +/- 36.2mg/dl; n =10), whereas serum levels were slightly decreased in diabetes patients (5049 +/- 196 mg/dl vs. 4330 +/- 186 mg/dl; p = 0.0283). This was comparable to an increase of IGF-I/11 and IGF-BP3 in vitreous from PDR patients (IGF-I: 2.3 +/- 1.1 ng/ml p = 0.005. IGF-II: 37.9 +/- 4.9 ng/ml; p = 0.0003. IGF-BP3: 97.9 +/- 26.9 ng/ml; p = 0.0001; n = 34) compared to controls (IGF-I: 0.7 +/- 0.1 ng/ml. IGF-II: 21.3 +/- 4.2 ng/ml. IGF-BP3: 31.3 +/- 4.9 ng/ml: n = 19). Serum levels did not differ significantly among the groups regarding IGF-I, II and IGF-BP3. Intraocular albumin and IGF-I levels calculated as percentage of the respective serum levels correlated significantly (r = 0.42; p = 0.012). This study demonstrates that influx of IGF-I, II and IGF-BP3 in PDR quantitatively parallels influx of the liver derived serum protein albumin suggesting that leakage of the blood retina barrier and serum levels of IGF primarily determine intravitreal IGF levels rather than local synthesis. Suppression of systemic IGF levels by new, highly effective somatostatin-analogues therefore provides a promising approach to prevent PDR.

Determination of endogenous growth factors in human wound fluid: temporal presence and profiles of secretion

Growth factors are important substances in the central control of wound healing during the exudative phase. Although these peptides have been applied frequently to chronic wounds in clinical studies, little is known about the naturally occurring levels at the wound site in correlation to healing in superficial wounds. We have therefore investigated the presence of these cytokines in partial thickness wounds. In 16 patients undergoing reconstructive surgery, split-thickness skin wounds were enclosed in cutaneous vinyl chambers filled with 2.5 ml of saline. Chambers placed over unwounded skin served as controls. After 24 hours, the accumulated wound fluid was harvested and replaced by 2.5 ml of saline until the wounds were healed. Wound fluid was centrifuged, aliquoted, and frozen at -70 degrees C. Samples were analyzed for protein and growth factors (insulin-like growth factor-1, epidermal growth factor, basic fibroblast growth factor, platelet-derived growth factor-AB, interleukin-1alpha, and transforming growth factor-beta1 and -beta2) and insulin-like growth factor-binding proteins 1 and 3 using a monoclonal Sandwich enzyme-linked immunosorbent assay and radioimmunoassay. All wounds healed in the liquid environment within 7 days (macroscopically) and 11 days (barrier function), respectively. In wound fluid, protein concentrations dropped from 5 mg/ml on day 1 to a baseline of 0.1 mg (unwounded skin), indicating a return of the barrier function. All growth factors could be measured already after 24 hours postwounding. However, the concentrations measured varied from 10 to more than 10,000 pg/ml between the different factors. The highest range was found for insulin-like growth factor-1 (21,000 to 41,000 pg/ml), the lowest for epidermal growth factor (3 to 63 and 3 to 88 pg/ml, respectively). Two different patterns of kinetics were distinguished: (1) a high initial peak decreasing to baseline values or below serum levels by the time of healing (insulin-like growth factor-1, insulin-like growth factor binding protein-1, -3, basic fibroblast growth factor, epidermal growth factor, platelet-derived growth factor-AB, transforming growth factor-beta1) and (2) a low initial concentration followed by an increase to a maximum at the time of epithelialization (interleukin-1alpha, transforming growth factor-beta2). Comparing the growth factor levels measured to serum baseline values, it was found that four of the growth factors appeared in wound fluid at above serum concentrations (interleukin-1alpha, transforming growth factor-beta2, basic fibroblast growth factor, epidermal growth factor); the other factors never reached serum values in wound fluid (insulin-like growth factor, transforming growth factor-beta1, platelet-derived growth factor-AB). It is concluded that the different profiles of secretion might reflect different functions of polypeptide growth factors such as stimulation of epithelialization (epidermal growth factor, insulin-like growth factor-1), matrix synthesis (transforming growth factor-beta), and inflammatory stimulation (interleukin-1alpha). The concentrations determined could serve as guidelines for adapted administration of growth factors once correlations to healing disorders such as overhealing and ulceration are established.

Genetic screening of prospective oocyte donors

OBJECTIVE

To report our experience with genetic screening of oocyte donor candidates and to determine the frequency with which significant genetic issues are identified.

DESIGN

Prospective genetic screening of oocyte donor candidates.

SETTING

University hospital oocyte donation program.

PATIENT(S)

Women presenting consecutively as volunteer oocyte donors.

INTERVENTION(S)

Genetic screening was performed by pedigree analysis and laboratory studies.

MAIN OUTCOME MEASURE(S)

Inclusion in the oocyte donor pool based on the results of clinical evaluation and laboratory tests consisting of polymerase chain reaction based mutational analysis for cystic fibrosis carrier status, cytogenetic analysis for karyotype, enzymatic assay for Tay-Sachs disease carrier status, and complete blood count and hemoglobin electrophoresis.

RESULT(S)

Eight (11%) of 73 oocyte donor candidates were excluded from the donor pool because of a potentially serious genetic finding. Cystic fibrosis mutations were identified in 5 candidates (7%), abnormal karyotypes were found in 2 (3.5%), and an autosomal dominant skeletal dysplasia was identified in 1 (1.4%).

CONCLUSION(S)

A significant proportion of women who present as candidates for oocyte donation are inappropriate for donation because of their genetic history or genetic testing results. A thorough genetic evaluation, including a history and laboratory screening, is essential to any oocyte donation program to maximize positive outcomes in pregnancies achieved through assisted means.

Carrier screening for cystic fibrosis, Gaucher disease, and Tay-Sachs disease in the Ashkenazi Jewish population: the first 1000 cases at New York University Medical Center, New York, NY

BACKGROUND

By late 1993, the genes for cystic fibrosis and Gaucher disease and the mutations common among Ashkenazi Jews had been identified. In response to these advances, heterozygote screening for cystic fibrosis and Gaucher disease was added to the more than 20-year-old Tay-Sachs disease screening program at New York University Medical Center, New York, NY.

OBJECTIVE

To review the outcomes from the first 1000 patients screened through this program.

METHODS

Patients and their referring physicians were informed about the new carrier tests. At the time of screening, patients could choose their tests (hexosaminidase A by enzyme analysis for Tay-Sachs disease or mutation analysis for cystic fibrosis and Gaucher disease). All partners of Tay-Sachs and cystic fibrosis carriers were tested. Prenatal diagnosis was offered and performed for carrier couples or mixed-marriage couples in whom the Ashkenazi Jewish partner was a carrier of Gaucher disease. Outcomes were measured by: (1) choice of tests, (2) decisions regarding prenatal diagnosis, and (3) phenotypes of children born to patients who underwent screening.

RESULTS

The majority of Ashkenazi Jewish patients chose to have testing for all 3 diseases. If they previously underwent screening for Tay-Sachs disease, then they chose to undergo testing for cystic fibrosis and Gaucher disease. All carrier couples for each of these diseases went on to have prenatal testing. All mixed-marriage couples in whom the Jewish partner was found to be a carrier for Gaucher disease chose to have prenatal diagnosis. One fetus was identified as having cystic fibrosis. Since the program was initiated, no Ashkenazi Jewish baby has been born with any of these diseases at New York University Medical Center.

CONCLUSIONS

New tests can be readily incorporated into established heterozygote screening programs. The Ashkenazi Jewish population described herein tends to choose testing for all conditions for which heterozygote screening is available.

Diagnosis of patent foramen ovale by transesophageal echocardiography and correlation with autopsy findings

Transesophageal echocardiography (TEE) is accepted as the method of choice for the diagnosis of the patent foramen ovale (PFO). However, direct anatomic confirmation regarding the presence or absence of a PFO on transesophageal imaging has been obtained in only a limited number of patients. Consequently, this study was performed to assess the diagnostic accuracy of contrast and color Doppler TEE for detection of a PFO by comparing the results of TEE with autopsy. The study population comprised 35 consecutive patients (mean age 64 +/- 14 years) who underwent autopsy and prior TEE with examination of the atrial septum. For diagnosis of a PFO, the following criteria were used: (1) no defect in the continuity of the atrial septum on 2-dimensional imaging; (2) > or = 1 bright microbubble appearing in left the atrium within 3 heart cycles after opacification of the right atrium during contrast TEE; and (3) turbulent color jet within the atrial septum by color Doppler TEE. For estimating the PFO size, positive contrast studies were graded semiquantitatively (from 1 to 3), and the maximal color Doppler jet width was measured within the atrium septum at the area of maximal turbulence. At autopsy, a PFO was present in 9 of 35 patients (26%). All were correctly diagnosed by color Doppler TEE. The color Doppler jet width correlated well with the PFO diameter determined at autopsy (r=0.99, SEE=0.51 mm, p<0.0001). By contrast TEE, 8 of the 9 patients with autopsy-proven PFO were correctly identified. In 1 case with left heart disease and a long interatrial channel, a PFO was missed by contrast TEE but clearly demonstrated by color Doppler TEE. All patients with a PFO diameter >10 mm showed intense left atrial opacification of grade 3. With both methods, there were no false-positive results. Sensitivity and specificity for diagnosis of a PFO were 89% and 100% respectively, for contrast TEE, and both 100% for color Doppler TEE. Thus, contrast and color Doppler TEE are complementary and represent a highly sensitive and specific method for diagnosis of a PFO and for estimation of the PFO size.

Hypophysitis in surgical and autoptical specimens

We present the clinical and histological findings of 11 cases of inflammatory anterior pituitary lesions, 8 of which were obtained during surgery and 3 of which were obtained from autopsies. Additionally, we extended the conventional classification of pituitary inflammatory disease by the new entity " secondary hypophysitis". Of the surgically obtained specimens 5 consisted of inflammatory extension into the pituitary gland out of the surrounding tissue. In all of these patients the inflammation originated from an additional tumor in the sellar region (4 craniopharyngiomas, 1 prolactinoma). These will be referred to as "secondary hypophysitis", an entity which has not yet been mentioned in the literature. Of the remaining 6 cases, 2 were granulomatous hypophysitis, 2 pituitary abscesses, 1 lymphocytic hypophysitis, and 1 showed extensive scarring of the anterior pituitary lobe due to preceeding lymphocytic hypophysitis. At histological examination the basic structure of the anterior pituitary was maintained in all cases. Relative counts of hormone-producing cells were normal. In secondary hypophysitis, the affected area was composed of fibrous tissue and granulation tissue. B and T lymphocytes were present in equal amounts. Granulomas were not found. Inflammatory infiltrates, granulation tissue and fibroses were seen in different proportions. Based on our results and three other cases reported in the literature so far, we think that the presently used classification of pituitary inflammatory diseases lacks an entity which describes a non-abscess-forming inflammation of the pituitary gland originating from an associated pathological process. Therefore, we introduced the term secondary hypophysitis to describe this fourth entity of pituitary inflammatory disease.

Glycosphingolipid expression on murine L1-fibrosarcoma cells: analysis of clonal in vivo and in vitro selected sublines with different lung colonisation potential

The patterns of acidic and neutral glycosphingolipids (GSLs) were examined in a syngeneic tumour system in Balb/c mice consisting of closely related cell lines with different colonisation potentials directed to the murine lungs (in vivo selected highly metastatic sublines of L1-fibrosarcoma cells and their WGA-resistant mutants with low metastatic potential). GSLs were analysed by high-performance thin-layer chromatography and structurally identified by fast atom bombardment mass spectrometry combined with compositional analyses and exo-glycosidase digestion. The results suggest that highly metastatic sublines L1-LM and L1-LM12 derived by in vivo selection from mouse fibrosarcoma cells (cell line L1) exhibit a drastic increase of polar ganglioside expression and a restriction to globo-series GSLs. Contrasting with this the low metastatic mutant cells (L1-LM13WGA) express a reduced portion of acidic GSLs and exhibit a shift to less polar ganglioside components. Total cellular and plasma membrane-integrated GSLs were demonstrated to exhibit largely identical patterns. Concomitant with a significant decrease in LacCer expression a substantial reduction of GM2 and a complete lack of GM3 expression can be assigned to the highly metastatic sublines of L1-cells. On the other hand, the more polar gangliosides GM1a and, to an even greater extent, GD1a (exceeding 70% of total gangliosides) accumulate on L1-LM and their clonal sublines. The shift to acidic GSLs of higher polarity is less pronounced on the low metastatic WGA-resistant mutant cells (L1-LM13WGA) showing a preponderance of GM1a. The portion of GD1a within the fractions of acidic GSLs does not correspond to the cellular activities of CMP-NeuAc/GM1 (alpha 2-3) sialyltransferase measured for high and low metastatic cell variants. Total sialic acid content of the various cell lines differs, but is not associated with the metastatic potential. Gangliosides on L1-cells exhibit a significant substitution of N-glycolyl for N-acetylneuraminic acid (13%) compared to their metastatic sublines and to mutant cells (less than 1%). A conversion of surface exposed GD1a to GM1a on membranes of metastatic cells by in situ treatment with Vibrio cholerae sialidase is associated with a significant reduction of tumour cell colonisation directed to the murine lungs.

A rare case of 68,XX triploidy diagnosed by amniocentesis

68,XX triploidy was found in the amniotic fluid cell culture of a 40-year-old patient. Elective termination of the pregnancy revealed a fetus with multiple congenital anomalies. While this case does show some common features with monosomy X, a greater similarity to the triploidy syndrome is observed.

Partial monosomy 13q and partial trisomy 18p: case report with necropsy findings

We describe a stillborn female infant with severe intrauterine growth retardation and multiple congenital anomalies. She was found to have a deletion of 13q22----qter and trisomy of 18p11.2----pter, resulting from a maternal balanced translocation.

alpha-Thalassemia hydrops fetalis: clinical and ultrasonographic considerations

Five pregnant Southeast Asian women presenting during a 14-month period with microcytic anemia, preeclampsia, and size-date discrepancies were all ultimately diagnosed as carrying fetuses with homozygous alpha-thalassemia hydrops fetalis. The perinatal complications of this hemoglobin disorder are unique to persons of this ethnic background and include uniform fatality for the affected infant, maternal preeclamptic morbidity, and retained placenta. In this report the obstetric ultrasound findings are presented and the clinical manifestations are discussed, with recommendations made to reduce this emerging public health problem in the United States.

The effect of ouabain on placental transport of 86Rb

Human placental fragments concentrate 86Rb 10--20-fold during a two-hour incubation period. Inhibition of ouabain is dose-dependent, reaching 90 + per cent at a concentration of 5 x 10(-5) M. The clearance index of 86Rb across the perfused human placenta is 0.34 +/- 0.08, comparing to previously reported indices for Na22 and Cl36 of 0.28 and 0.41, respectively. Ouabain in concentrations up to 5 x 10(-5) M had no detectable effect on transfer across the placenta. The clearance index of ouabain is low, averaging 0.07 in 3 experiments. 3H-ouabain is not detectably bound to albumin or placental homogenate.

Hair root analysis in X-linked ichthyosis

Hair roots have been analysed in a large kindred with X-linked ichthyosis associated with steroid sulphatase deficiency. Enzyme activity in individual hair roots was assayed for the steroid sulphatase:neutral alpha-glucosidase ratio, the latter serving as an indicator of the general metabolic activity of the hair root. The distribution of the enzyme ratios in the individual hair roots in the heterozygotes described a normal curve suggesting origin from a single population of cells. The results differed strikingly from the irregular distribution of enzyme activities in hair roots of Lesch-Nyhan disease, where mosaicism occurs. It is suggested that the maternal and paternal genes for steroid sulphatase remain active in vivo in each cell in the hair root in apparent contradiction to the Lyon hypothesis. The observation is consistent with that previously reported for skin fibroblasts in vitro. Sulphatase activity in female controls was minimally greater than in males but the difference was not statistically significant.

Transfer of urea, sodium, and chloride across the perfused human placenta

Clearance indices (clearance of experimental material: clearance of antipyrine, CI) across the perfused human placenta were determined for urea, sodium, and chloride. The selected materials are of relatively small molecular weight and are water soluble. Clearance of urea was determined under conditions of net transfer and of exchange and no difference was detected. Sodium and chloride clearances were measured as exchange rates. The CI were: urea, 0.32 and 0.38 toward fetus and mother, respectively); sodium, 0.28; and chloride, 0.41 (measured toward the fetus). Recalculation of data as the diffusion limitation (LD) facilitated comparison with data in the literature on the monkey, rabbit, and sheep. LD for urea was comparable among the four species whereas the sheep placenta differed, sharply limiting the diffusion of sodium and chloride. The discrepancy in the sheep between urea and sodium indicates that the low transfer rate of the latter cannot be explained by the "thickness" of the syndesmochorial placenta, as is often stated. Inferences concerning nitrogen metabolism in the fetus have been derived by others from data on transplacental urea gradients and urea clearance. Available data in the human are incomplete but are consistent with amino acids providing approximately 10% of fetal energy needs, with glucose serving as the predominant substrate.

Characterization of the (rnunz) nude rat. Morphological characteristics of the lymphoid system

A nude mutant (rnunz) arose spontaneously in a colony of Wistar albino rats (the wild-type strain) in Wellington, New Zealand. On gross examination no thymus could be found in the mediastina of young animals, whereas in older mutants lobules of fatty tissue mimicked the appearance of the thymus of the wild-type strain. Lymph nodes from the rnunz strain showed a marked lymphocyte depletion in the thymus-dependent para-cortical region of the node. Peyer's patches from the nude animals also showed a reduced density of small lymphocytes in the interfollicular zones. In the spleen, tissue from the reticular framework surrounding individual arterioles was sometimes completely empty of lymphocytes but the degree of depletion varied. Total leucocyte numbers in the rnunz strain were 28% lower than the wild-type strain. In 10 out of 13 animals T cells were less than 3% of the lymphocytes present (wild-type 35% T cells). The findings are in agreement with studies of the Rowett nude rat (rnu) and the nude mouse.

Placental transfer of steroids: effect of binding to serum albumin and to placenta

The transfer rates and placental retention of a series of steroids were measured using an in vitro perfusion system of an isolated cotyledon of human placenta. The steroids were added to the maternal inflow and rates of appearance in maternal and fetal outflows were measured, from which data were calculated the transfer rate and placental retention. With a low concentration of albumin (0.01 g/dl) in the maternal and fetal perfusates, transfer rates of diethylstilbestrol and ethynylestradiol were initially low, with considerable retention of the steroids within the placenta. Transfer rates increased with duration of perfusion. With high concentrations of albumin (1 g/dl), placental retention was greatly reduced and transfer rates very rapidly reached high levels. Albumin in the fetal circulation was the effective factor in increasing transfer rate; maternal albumin reduced it. The results with estrone and progesterone were qualitatively similar but not as striking, posssibly because of the large endogenous concentrations of these two hormones. Placental retention of dexamethasone, a more polar steroid that does not bind to placenta and binds poorly to albumin, was low and there was little difference between transfer from low- and high-protein perfusates.

Secretory proteins in the perfused human placenta

A relatively simple perfusion technique of human placenta has been applied to the study of secretory proteins. Preferential secretion into the maternal circulation of human chorionic gonadotropin (HCG), human chorionic somatomammotropin (HCS), follicle-stimulating hormone (FSH), and placental alkaline phosphatase has been demonstrated, contrasting with the bidirectional secretion of progesterone. Evidence is presented for the net synthesis of HCS during perfusion. The technique offers advantages in the study of synthesis and secretion of placental materials.

The transfer and metabolism of corticosteroids in the perfused human placenta

The transfer and metabolism of cortisol, prednisolone, betamethasone, and dexamethasone were investigated in vitro in the perfused human placenta. Maternal and fetal circuits were established but the steroid was added to the former only. The clearance expressed as a fraction of the antipyrine transfer rate varied from 0.27 to 0.50, but there were no significant differences among the four steroids. All the steroids were metabolized extensively to their respective 11-ketosteroids and again there were no material differences among the steroids. The metabolic conversions of dexamethasone and betamethasone were far greater in the perfused placenta than in minced placenta. From the standpoint of placental transfer and metabolism, as observed in the perfusion studies, none of the four corticosteroids offers a decisive advantage in the antepartum maturation of the fetal pulmonary surfactant system.

Effect of protein binding on transfer and metabolism of cortisol in perfused human placenta

The transfer and metabolism of cortisol and cortisone and the effect of protein binding on these processes have been investigated in vitro in the perfused human placenta. The clearance of cortisol in buffer, expressed as a fraction of the antipyrine transfer rate (clearance index), was 0.50 +/- 0.05 SEM in either direction. Extensive conversion to cortisone (85%) occurred during transfer. Addition of corticosteroid-binding globulin (CBG) in amounts sufficient to bind 50% of the cortisol reduced the clearance (0.40 +/- .026) insignificantly, whereas human serum albumin (HSA) in amounts sufficient to bind 50% of the cortisol reduced the clearance to 0.28 +/- 0.012 (P less than 0.001) even though the association constant for albumin is approximately 1000-fold less. The percent of conversion to cortisone did not change significantly with protein binding. The clearance index of cortisone from a protein-free perfusate was 0.74. With CBG and albumin in the same concentrations as used in the cortisol experiments, the binding of cortisone to CBG was 23% and its clearance was 0.70; with albumin, the binding was 45% and the clearance index was 0.45. The addition of albumin and CBG to the same perfusate resulted in a cortisol clearance equal to that obtained with perfusate containing only albumin. Binding to albumin may be more significant than binding to CBG in controlling the transfer rate of cortisol to the fetus.

Treatment of hypoplastic anemia in mice with placental transplants

A genetic mutation in mice (W/Wv) causes an autosomal recessive disease characterized by hypoplastic anemia which lasts throughout life. Double-dominant W/Wv anemic mice were sublethally irradiated to facilitate repopulation of marrow with transplanted cells and were injected intravenously with suspensions of 5-10 million placental cells of 15 days gestation derived from normal, isogeneic donors. Red cell counts fell promptly after irradiation and then rose progressively over a period of weeks, reaching normal levels of the nonmutant. Mean corpuscular volume and hemoglobin electrophoresis patterns of red cells in recipient W/Wv mice resembled those of normal donor animals. The therapeutic effect lasted for the duration of the observation period, in some instances over 9 mo. W/Wv mice that were administered Hanks' solution or fetal blood, instead of placental transplants, remained anemic. Late gestation placentas (18 days) were also ineffective.

Transfer across perfused human placenta. IV. Effect of protein binding on free fatty acids

The effect of protein binding on the rate of placental transfer of hexanoic (C 6) and decanoic (C 10) acids was investigated in an in vitro perfusion system of human placenta. As much as 30% of transferred C 6 was converted to more polar compounds, so that the observations related to the combined effects on transfer and metabolism. Less than 10% of C 10 was similarly metabolized. Both fatty acids are soluble in buffered salt solutions at the concentrations used (40 muM) and both are bound to serum albumin, C-10 having higher association constants (K' for C 6, 1.48 X 10(4); for C 10, 1.03 X 10(5). When the placenta is perfused with buffered salt solution, the transfer of C 6 is 22% more rapid than that of C 10. It is suggested that binding within the placenta retards C 10 more than C 6. The addition of 1 g/100 ml bovine serum albumin to the maternal perfusate reduces the transfer rate of C 10 by 80%, whereas 2 g/100 ml serum albumin has a more moderate effect on C 6 (a reduction of 50%). The addition of 1 g/100 ml serum albumin to the fetal perfusate increases transfer rate of both free fatty acids (FFA), C 6 by 25% and C 10 by about 250%. With equivalent concentrations of serum albumin in maternal and fetal perfusates, the transfer rate of C 10 was reduced by 65%, whereas there was no detectable effect on transfer of C 6 in two of three experiments. The transfer rate of FFA increase logarithmically with progressive shortening of the carbon chain from C 16 to C 8 when maternal and fetal perfusates contain serum albumin. Protein binding is apparently the determining factor. The rate of transfer falls off at C 6 and C 4, 4ven though protein-binding continues to decrease. The determining factor may be the hydrophilic nature of these molecules.