Alveolar Differentiation Drives Resistance to KRAS Inhibition in Lung Adenocarcinoma

Lung adenocarcinoma (LUAD), commonly driven by KRAS mutations, is responsible for 7% of all cancer mortality. The first allele-specific KRAS inhibitors were recently approved in LUAD, but the clinical benefit is limited by intrinsic and acquired resistance. LUAD predominantly arises from alveolar type 2 (AT2) cells, which function as facultative alveolar stem cells by self-renewing and replacing alveolar type 1 (AT1) cells. Using genetically engineered mouse models, patient-derived xenografts, and patient samples, we found inhibition of KRAS promotes transition to a quiescent AT1-like cancer cell state in LUAD tumors. Similarly, suppressing Kras induced AT1 differentiation of wild-type AT2 cells upon lung injury. The AT1-like LUAD cells exhibited high growth and differentiation potential upon treatment cessation, whereas ablation of the AT1-like cells robustly improved treatment response to KRAS inhibitors. Our results uncover an unexpected role for KRAS in promoting intratumoral heterogeneity and suggest that targeting alveolar differentiation may augment KRAS-targeted therapies in LUAD.

SIGNIFICANCE

Treatment resistance limits response to KRAS inhibitors in LUAD patients. We find LUAD residual disease following KRAS targeting is composed of AT1-like cancer cells with the capacity to reignite tumorigenesis. Targeting the AT1-like cells augments responses to KRAS inhibition, elucidating a therapeutic strategy to overcome resistance to KRAS-targeted therapy. This article is featured in Selected Articles from This Issue, p. 201.

Alveolar differentiation drives resistance to KRAS inhibition in lung adenocarcinoma

Lung adenocarcinoma (LUAD), commonly driven by KRAS mutations, is responsible for 7% of all cancer mortality. The first allele-specific KRAS inhibitors were recently approved in LUAD, but clinical benefit is limited by intrinsic and acquired resistance. LUAD predominantly arises from alveolar type 2 (AT2) cells, which function as facultative alveolar stem cells by self-renewing and replacing alveolar type 1 (AT1) cells. Using genetically engineered mouse models, patient-derived xenografts, and patient samples we found inhibition of KRAS promotes transition to a quiescent AT1-like cancer cell state in LUAD tumors. Similarly, suppressing Kras induced AT1 differentiation of wild-type AT2 cells upon lung injury. The AT1-like LUAD cells exhibited high growth and differentiation potential upon treatment cessation, whereas ablation of the AT1-like cells robustly improved treatment response to KRAS inhibitors. Our results uncover an unexpected role for KRAS in promoting intra-tumoral heterogeneity and suggest targeting alveolar differentiation may augment KRAS-targeted therapies in LUAD.

Significance

Treatment resistance limits response to KRAS inhibitors in LUAD patients. We find LUAD residual disease following KRAS targeting is composed of AT1-like cancer cells with the capacity to reignite tumorigenesis. Targeting the AT1-like cells augments responses to KRAS inhibition, elucidating a therapeutic strategy to overcome resistance to KRAS-targeted therapy.

Prognostic Factors for Attempted Finger Replantation and Revascularisation after Traumatic Amputation: A 16-Year Retrospective Cohort Study

Background: The aim of this study was to evaluate the impact of variant factors on finger replantation and revascularisation after traumatic amputation, which also included duty shift and the level of main operator. Methods: To determine the prognostic factors for the survival rate of finger replantation and revascularisation after traumatic finger amputation, we retrospectively reviewed the cases of finger replantation conducted from January 2001 to December 2017. Data collected consisted of the basic information of the patients, trauma-related factors, details of the operation and treatment outcomes. Descriptive statistics and data analysis was performed to assess outcomes. Results: In total, 150 patients with 198 replanted digits were enrolled in this study. The median age of the participants was 42.5 years, and 132 (88%) patients were men. The overall successful replantation rate was 86.4%. Seventy-three (36.9%) digits had Yamano type 1 injury; 110 (55.6%), Yamano type 2 injury and 15 (7.6%), Yamano type 3 injury. In total, 73 (36.9%) digits were completely amputated and 125 (63.1%) were not. Half of the replantation procedures (101, 51.0%) were performed during night shift (16:00-00:00), 69 (34.8%) during day shift (08:00-16:00) and 28 (14.1%) during graveyard shift (00:00-08:00). Multivariate logistic regression demonstrated that the trauma mechanism and type of amputation (complete vs. incomplete) significantly affect the survival rate of replantation. Conclusions: The trauma mechanism and type of amputation (complete vs. incomplete) significantly affect the survival rate of replantation. Other factors including duty shift and the level of operator did not reach statistically significance. Further studies must be conducted to validate the results of the current study. Level of Evidence: Level III (Prognostic).

Abstract B006: Targeting keratin 17-mediated metabolic reprogramming of de novo pyrimidine biosynthesis as a novel strategy to overcome chemoresistance in pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) is a leading cause of cancer death. We previously reported that keratin 17 (K17) is a negative prognostic and predictive biomarker, whose overexpression confers the resistance to chemotherapies. Here, we investigated the mechanisms of chemoresistance and tumor-specific vulnerabilities that can be exploited for the development of novel targeted therapies for K17-expressing PDAC. We hypothesized that K17 reprograms cancer metabolism and leads to therapeutic resistance. To test this, we manipulated the expression of K17 in multiple in vitro and in vivo models of PDAC, spanning human and murine PDAC cells and orthotopic xenografts. Unbiased metabolomic studies in isogenic PDAC models identified several key metabolic pathways that are upregulated in the presence of K17, including glycolysis, purine biosynthesis, and pyrimidine biosynthesis. We demonstrate that K17 increases pyrimidine biosynthesis, a pathway that has been linked to chemoresistance. Patient dataset analysis revealed that K17 expression and enzymes involved in pyrimidine, but not purine, de novo biosynthesis are associated with shorter patient survival. To address how altered nucleotide biosynthesis contributes to chemoresistance, we performed drug-response experiments with exogenous nucleosides. We found that deoxycytidine (dC) and deoxythymidine (dT) are sufficient to promote resistance to Gemcitabine (a dC analog) and 5-fluorouracil (a dT analog), respectively. To further evaluate therapeutic opportunity by targeting K17-dependent pyrimidine biosynthesis, we tested compounds that inhibit individual nucleotide biosynthetic pathways. We found that K17-expressing cells were more sensitive to Brequinar, a specific inhibitor of dihydroorotate dehydrogenase (DHODH), the rate-limiting enzyme in de novo pyrimidine biosynthetic pathway. Targeting DHODH by siRNA or by Brequinar had synergistic effects when combined with Gemcitabine in inhibiting cell viability of K17-positive cells, revealing a druggable pathway dependency for K17-positive tumors. Currently, we are testing the combination of Brequinar and Gemcitabine in our animal models. Overall, we identified a novel pathway of chemoresistance and a target which could lead to the development of a biomarker-based therapy for K17-expressing PDAC.

Citation Format: Chun-Hao Pan, Robert Tseng, Michael Horowitz, Md Afjalus Sira, Bo Chen, Katie L. Donnelly, Cindy V. Leiton, Natalia Marchenko, Pankaj K. Singh, Kenneth R. Shroyer, Luisa F. Escobar-Hoyos. Targeting keratin 17-mediated metabolic reprogramming of de novo pyrimidine biosynthesis as a novel strategy to overcome chemoresistance in pancreatic cancer [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer; 2022 Sep 13-16; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2022;82(22 Suppl):Abstract nr B006.

Dihydroceramide desaturase 1 (DES1) promotes anchorage-independent survival downstream of HER2-driven glucose uptake and metabolism

Oncogenic reprogramming of cellular metabolism is a hallmark of many cancers, but our mechanistic understanding of how such dysregulation is linked to tumor behavior remains poor. In this study, we have identified dihydroceramide desaturase (DES1)-which catalyzes the last step in de novo sphingolipid synthesis-as necessary for the acquisition of anchorage-independent survival (AIS), a key cancer enabling biology, and establish DES1 as a downstream effector of HER2-driven glucose uptake and metabolism. We further show that DES1 is sufficient to drive AIS and in vitro tumorigenicity and that increased DES1 levels-found in a third of HER2+ breast cancers-are associated with worse survival outcomes. Taken together, our findings reveal a novel pro-tumor role for DES1 as a transducer of HER2-driven glucose metabolic signals and provide evidence that targeting DES1 is an effective approach for overcoming AIS. Results further suggest that DES1 may have utility as a biomarker of aggressive and metastasis-prone HER2+ breast cancer.

Neutralizing activity to SARS-CoV-2 of convalescent and control plasma used in a randomized controlled trial

Background

There are limited data on the neutralizing activity of convalescent plasma (CP) administered in randomized controlled trials (RCT) of COVID‐19 infection.

Study Design and Methods

As part of an RCT, CP was collected per FDA guidelines from individuals recovered from COVID‐19 infection. CP donors had to have ≥145 optical density (OD) units (ideal target ≥300) using a semiquantitative, immunochromatographic test for IgG antibody to the nucleocapsid protein (NP) of SARS‐CoV‐2 (typical range 0–500 OD units). A random subset of samples [14 control plasma, 12 CP “medium‐anti‐NP” (145–299 OD units), and 13 CP “high” anti‐NP (≥300 OD units)] were tested for neutralizing antibodies using an established viral luciferase antibody inhibition assay to detect the infection of SARS‐CoV‐2 pseudovirus that encoded spike protein (SARS2‐S_trunc) on a human immunodeficiency virus 1 vector (NL43dEnvNanoLuc), using ACE2‐expressing 293 T cells. The titer needed to neutralize 50% of viral activity (NT50) was calculated.

Results

The uptake of SARS‐CoV‐2 pseudovirus by 293T_ACE2 cells was inhibited by pretreatment with CP compared to control CP (p < .001) with control plasma having a median (IQR) 50% neutralization titer (NT50) of 1:28 (1:16,1:36) compared to 1:334 (1:130,1:1295) and 1:324 (1:244,1:578), for medium anti‐NP and high anti‐NP CP units, respectively. The neutralizing activity of CP met minimum FDA criteria with neutralizing antibody titers >1:80 in 100% of randomly selected samples, using a conservative approach that excluded non‐specific binding.

Discussion

Plasma from donors screened using an immunochromatographic test for IgG antibody to SARS‐CoV‐2 NP exhibited neutralizing activity meeting FDA's minimum standard in all randomly selected COVID‐19 CP units.

Abstract PO-040: Therapeutic targeting of keratin 17 functional domains and nuclear export uncover therapeutic vulnerabilities of pancreatic cancer

The purpose of this study is to launch a novel biomarker-based targeted therapy that may result in improved precision and efficacy for the treatment of pancreatic ductal adenocarcinoma (PDAC). We discovered that Keratin 17 (K17), an oncofetal intermediate filament and nuclear oncoprotein expressed in 50% of PDAC cases, is a biomarker of the most aggressive and treatment-resistant form of PDAC. We set out to validate K17 as a druggable target and to identify K17-targeting mechanisms. In pre-clinical mouse models, animals bearing K17+ PDACs display the shortest survival, suggesting that K17 drives tumor aggression and should be explored as a potential therapeutic target. We used the following two approaches aimed to inhibit K17 nuclear shuttle functions, in order to identify therapeutic strategies: 1) Targeting K17 functional domains: By protein-sequence modeling analyses and site-directed mutagenesis, we identified functional domains in K17 (K17-FDs) that bind to, shift the subcellular localization of, and promote the degradation of nuclear tumor suppressors (e.g. p27). Using SILAC mass spectrometry of nuclear proteomes from isogenic human cells, we found that 80% of the nuclear proteome is altered by K17, that half of these proteins encode the domain targeted by the K17-FDs, and that a large proportion of these proteins are involved in gene expression. Animals harboring tumors with mutated K17-FDs lived two-times longer than control animals bearing K17+ PDACs, suggesting that the K17-FDs may be therapeutic targets. We are currently testing small molecule and peptide inhibitors to target the K17-FDs in vitro and in vivo, as a discovery approach to design small-molecule inhibitors of K17. 2) Targeting K17 nuclear export: K17 impacts the nuclear export of ~50% of the proteome and depends on exportin-1 (XPO1). We found that K17+ PDAC cells were more sensitive to Selective Inhibitor of Nuclear Export (SINE) therapy, leading to a 2-fold increase in cell death compared to control cells, suggesting that nuclear export by K17 in PDAC cells could be therapeutically targeted. SINE therapy is currently FDA-approved for treatment of other cancer types and repurposing for the treatment of K17-positive PDACs may result in enhanced therapeutic efficacy. In conclusion, these studies provide the basis for the development of novel biomarker-based therapeutic approaches using small-molecule inhibitors, to target K17 active sites or the pathways altered by this protein in PDAC.

Citation Format: Cindy V. Leiton, Chun-Hao Pan, Ji Dong Bai, Lucia Roa-Peña, Sruthi Babu, Alex Penson, Nashaat Turkman, Richard Moffitt, Markus Seeliger, David Talmage, Kenneth R. Shroyer, Luisa F. Escobar-Hoyos. Therapeutic targeting of keratin 17 functional domains and nuclear export uncover therapeutic vulnerabilities of pancreatic cancer [abstract]. In: Proceedings of the AACR Virtual Special Conference on Pancreatic Cancer; 2020 Sep 29-30. Philadelphia (PA): AACR; Cancer Res 2020;80(22 Suppl):Abstract nr PO-040.

Altered RNA Splicing by Mutant p53 Activates Oncogenic RAS Signaling in Pancreatic Cancer

Pancreatic ductal adenocarcinoma (PDAC) is driven by co-existing mutations in KRAS and TP53. However, how these mutations collaborate to promote this cancer is unknown. Here, we uncover sequence-specific changes in RNA splicing enforced by mutant p53 which enhance KRAS activity. Mutant p53 increases expression of splicing regulator hnRNPK to promote inclusion of cytosine-rich exons within GTPase-activating proteins (GAPs), negative regulators of RAS family members. Mutant p53-enforced GAP isoforms lose cell membrane association, leading to heightened KRAS activity. Preventing cytosine-rich exon inclusion in mutant KRAS/p53 PDACs decreases tumor growth. Moreover, mutant p53 PDACs are sensitized to inhibition of splicing via spliceosome inhibitors. These data provide insight into co-enrichment of KRAS and p53 mutations and therapeutics targeting this mechanism in PDAC.

Penalized full likelihood approach to variable selection for Cox's regression model under nested case-control sampling

Assuming Cox's regression model, we consider penalized full likelihood approach to conduct variable selection under nested case-control (NCC) sampling. Penalized non-parametric maximum likelihood estimates (PNPMLEs) are characterized by self-consistency equations derived from score functions. A cross-validation method based on profile likelihood is used to choose the tuning parameter within a family of penalty functions. Simulation studies indicate that the numerical performance of (P)NPMLE is better than weighted partial likelihood in estimating the log-relative risk and in identifying the covariates and the model, under NCC sampling. LASSO performs best when cohort size is small; SCAD performs best when cohort size is large and may eventually perform as well as the oracle estimator. Using the SCAD penalty, we establish the consistency, asymptotic normality, and oracle properties of the PNPMLE, as well as the sparsity property of the penalty. We also propose a consistent estimate of the asymptotic variance using observed profile likelihood. Our method is illustrated to analyze the diagnosis of liver cancer among those in a type 2 diabetic mellitus dataset who were treated with thiazolidinediones in Taiwan.

Abstract B50: Keratin 17 drives tumor aggression and could be targeted for treatment of pancreatic ductal adenocarcinoma

Our aims are to uncover the molecular mechanisms through which keratin 17 (K17), a prognostic biomarker, drives tumor aggression and to target these mechanisms to provide more effective treatment for pancreatic ductal adenocarcinoma (PDAC). In murine orthotopic xenografts, we found that K17-positve PDACs survive for a shorter interval than controls. Prompted by previous reports that post-translational modifications (PTMs) regulate intermediate filament dynamics, we established in vitro that phosphorylated K17 detaches from the cytoskeleton and enters the nucleus, where it promotes tumor growth by targeting tumor suppressor proteins, including p27, for nuclear export and degradation. To further understand the events that control K17 solubilization, we sequenced K17 from primary PDACs by liquid chromatography-mass spectrometry and identified serine sites within the N-terminus that are phosphorylated only in soluble K17. Furthermore, phosphorylation is required to maintain K17 solubility and soluble K17 accumulates in the nucleus of PDAC cells. By an unbiased screen of 80 small-molecule kinase inhibitors in PDAC, we determined that SYK kinase inhibitors, already in clinical trials for other malignancies, abrogated K17 solubilization. Prompted by our finding that K17 serves as a nuclear shuttle of p27, we identified two amino acid sequences in K17 that have similar polarity to sequences that are used by cyclins to dock to p27. Point mutations in two of these domain key residues blocked K17-mediated degradation of nuclear p27, and we identified similar effects in the background of wild-type and oncogenic KrasG12D PDAC cells. Current studies are under way to find additional protein and RNA targets for potential therapeutic intervention. Using patient-derived organoids, human and murine PDAC cells, we determined that K17-expressing PDAC cells are more than twice as resistant as isogenic K17-negative cells to gemcitabine (Gem) and 5-fluorouracil (5-FU), two key components of current chemotherapeutic regimens. By unbiased liquid chromatography-coupled tandem mass spectrometry metabolomics, RNA-sequencing analyses (TCGA), and in vivo magnetic resonance spectroscopy, we found that K17 induces metabolic reprogramming by increasing glycolysis and pyrimidine biosynthesis, pathways that have been linked to chemoresistance. We are extending this work to determine if disruption of K17-mediated metabolic rewiring by small-molecule inhibitors will resensitize tumor cells to pyrimidine analogues. In conclusion, K17 undergoes key post-translational modifications that enable solubilization and nuclear translocation, the targeting of tumor suppressor proteins, and enhanced pyrimidine biosynthesis to drive chemoresistance. Uncovering these mechanisms could ultimately lead to the identification of novel approaches to target the oncogenic functions of K17, and thereby, to enable the development of more effective treatment options for PDAC.

Citation Format: Kenneth R. Shroyer, Luisa Escobar-Hoyos, Cindy Leiton, Chun-Hao Pan, Ryan Kawalerski, Lucia Roa-Peña, Sruthi Babu. Keratin 17 drives tumor aggression and could be targeted for treatment of pancreatic ductal adenocarcinoma [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer: Advances in Science and Clinical Care; 2019 Sept 6-9; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2019;79(24 Suppl):Abstract nr B50.

Abstract C32: Therapeutic targeting of keratin 17 and nuclear export uncover therapeutic vulnerabilities of pancreatic cancer

The purpose of this study is to launch a novel biomarker-based targeted therapy that may result in improved precision and personalized medicine for pancreatic ductal adenocarcinoma (PDAC). We discovered that keratin 17 (K17), an intermediate filament (IF), is a nuclear oncoprotein found in 50% of PDAC cases, identifying the most aggressive and treatment-resistant form of PDAC and functioning as a biomarker. We set out to validate K17 as a druggable target and to identify K17-targeting mechanisms. In preclinical mouse models, animals bearing K17-expressing PDACs display the shortest survival interval, suggesting that K17 drives tumor aggression and is a potential therapeutic target. We used the following two approaches aimed to inhibit K17 nuclear shuttle functions in order to identify potential therapeutic strategies. 1) Targeting K17 functional domains: By protein-sequence modeling analyses and site-directed mutagenesis, we identified functional domains in K17 (K17-FDs) that bind to, shift the subcellular localization of, and promote the degradation of nuclear tumor suppressors (i.e., p27). Using SILAC mass spectrometry analysis of nuclear proteomes from isogenic human cells, we found that 80% of the nuclear proteome is altered by K17, that half of these proteins encode the domain targeted by the K17-FDs, and that a large proportion of these proteins are involved in gene expression. Animals harboring tumors with mutated K17-FDs lived two times longer than control animals, suggesting that the K17-FDs may be therapeutic targets. We are currently testing small-molecule and peptide inhibitors to target the K17-FDs in vitro and in vivo, as a discovery approach to design small-molecule inhibitors of K17. 2) Targeting K17 nuclear export: K17 impacts the export of ~50% of the proteome and depends on exportin-1 (XPO1) for nuclear export. We found that PDAC cells expressing K17 were more sensitive to Selective Inhibitor of Nuclear Export (SINE) therapy, leading to a 2-fold increase in cell death compared to control cells, suggesting that nuclear export is a necessary oncogenic pathway exploited by K17 in PDAC cells. SINE therapy is currently FDA approved for treatment of other cancer types, and repurposing for the treatment of K17-positive PDACs may result in enhanced therapeutic efficacy. In conclusion, these studies provide the basis for novel biomarker-based therapeutic approaches for the most aggressive PDAC cases using small-molecule inhibitors that directly target K17 active sites or the pathways altered by this protein.

Citation Format: Cindy V. Leiton, Chun-Hao Pan, Ji Dong Bai, Lucia Roa-Peña, Sruthi Babu, Alex Penson, Nashaat Turkman, Richard Moffitt, Markus Seeliger, David Talmage, Kenneth R. Shroyer, Luisa F. Escobar-Hoyos. Therapeutic targeting of keratin 17 and nuclear export uncover therapeutic vulnerabilities of pancreatic cancer [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer: Advances in Science and Clinical Care; 2019 Sept 6-9; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2019;79(24 Suppl):Abstract nr C32.

Abstract C39: A novel rewired pathway of nucleotide metabolism drives chemoresistance in pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) is characterized by two molecular subtypes, of which the basal-like subtype is associated with the worst survival and is highly resistant to the currently available first-line chemotherapy. Our laboratory has identified that keratin 17 (K17) is a novel negative prognostic biomarker, as accurate as molecular subtyping in predicting patient survival. Patient-derived data analysis suggests that K17 expression correlates with increased resistance to chemotherapeutic agents. The goal of this study is to determine the role of K17 in chemoresistance, and to identify novel therapeutic approaches for around 50% of PDAC patients with tumors that express high levels of K17. In multiple in vivo and in vitro models of PDAC, spanning human and murine PDAC cells, patient-derived organoids, and orthotopic xenograft models, we determined that K17 expression causes more than two-fold increase in resistance to gemcitabine (Gem) and 5-fluorouracil (5-FU), key components of the current standard-of-care chemotherapeutic regimens. To uncover the mechanism associated to K17-induced chemoresistance, we performed unbiased metabolomic studies in isogenic PDAC cell lines and found that K17 reprograms several key metabolic pathways. In particular, K17 increases pyrimidine biosynthesis, a pathway has been linked to chemoresistance. Rescue experiments showed that deoxycytidine (dC) was sufficient to promote Gem (dC analogue) resistance in K17-nonexpressing PDAC cells, suggesting that upregulation of pyrimidine synthesis by K17 underlies resistance to chemotherapeutic agents. Through unbiased RNA-sequencing studies, we identified that gene expression of enzymes involved in pyrimidine biosynthesis was increased specifically in high K17-expressing cells. Previous reports from our group and others suggest that nuclear K17 regulates cell-cycle progression and gene expression. Through domain-prediction analyses, we discovered a novel domain on K17 involved in transcriptional regulation that is required for metabolic reprogramming. Currently, we are testing the role of this domain in metabolic reprograming. In addition, are pursuing two approaches to determine the “druggability” of these findings. First, we are testing if interrupting K17-mediated nucleotide metabolism, by means of small-molecule inhibitors, resensitizes tumor cells to pyrimidine analogues. Second, we are validating the results of a large-scale small-molecule inhibitor screen of FDA-approved, pharma-developed tools to identify compounds that target DNA metabolism and transcription in K17-expressing PDAC cells. In summary, we identified a novel and potentially druggable pathway of chemoresistance that could ultimately result in developing novel therapeutic strategies to enhance patient survival.

Citation Format: Chun-Hao Pan, Cindy V. Leiton, Lucia Roa-Peña, Ryan R. Kawalerski, Richard A. Moffitt, Jiang Zhao, Timothy Spicer, Peter Bailey, David K. Chang, Andrew Biankin, Tim Duong, Pankaj K. Singh, Kenneth R. Shroyer, Luisa F. Escobar-Hoyos. A novel rewired pathway of nucleotide metabolism drives chemoresistance in pancreatic cancer [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer: Advances in Science and Clinical Care; 2019 Sept 6-9; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2019;79(24 Suppl):Abstract nr C39.

The PHLPP2 phosphatase is a druggable driver of prostate cancer progression

Nowak et al. show that loss of the AKT-inactivating phosphatase PHLPP2 paradoxically blocks prostate tumor growth and metastasis. PHLPP2, they find, is critical for MYC stability, suggesting that PHLPP2 inhibitors may present a therapeutic opportunity to target MYC.

Metastatic prostate cancer commonly presents with targeted, bi-allelic mutations of the PTEN and TP53 tumor suppressor genes. In contrast, however, most candidate tumor suppressors are part of large recurrent hemizygous deletions, such as the common chromosome 16q deletion, which involves the AKT-suppressing phosphatase PHLPP2. Using RapidCaP, a genetically engineered mouse model of Pten/Trp53 mutant metastatic prostate cancer, we found that complete loss of Phlpp2 paradoxically blocks prostate tumor growth and disease progression. Surprisingly, we find that Phlpp2 is essential for supporting Myc, a key driver of lethal prostate cancer. Phlpp2 dephosphorylates threonine-58 of Myc, which renders it a limiting positive regulator of Myc stability. Furthermore, we show that small-molecule inhibitors of PHLPP2 can suppress MYC and kill PTEN mutant cells. Our findings reveal that the frequent hemizygous deletions on chromosome 16q present a druggable vulnerability for targeting MYC protein through PHLPP2 phosphatase inhibitors.

The role of preliminary hospitals in the management of a mass burn casualty disaster

PURPOSE

The Formosa Fun Coast explosion is an internationally-known event that occurred in Taiwan on June 27th, 2015. The blast involved 495 casualties in total, with 253 patients receiving 2nd degree or deeper burns on greater than 40% of the total body surface area (TBSA). Questions were raised regarding whether these victims were sent to the appropriate hospitals or not. Therefore, we analyzed the effect of the initial admission destination in this study.

MATERIAL AND METHODS

We retrospectively reviewed all of the victims from the explosion who were sent to the emergency department of Linkou and Keelung Chang Gung Memorial Hospitals. Patients were divided by direct admission and received via transfer. The basic demographics, the efficacy of the initial resuscitation and the clinical outcomes were analyzed.

RESULTS

In total, forty-six patients were included. Thirty-five of them were primarily admitted, and eleven of them were received via transfer. Between the two groups, there was no significant difference in the resuscitation outcome. The ratio of delaying intubation was similar (14.3% vs 27.3%, p=0.322). The rate of delayed-detected ischemic events was significantly increased in the referral group (0% vs 27.3%, p=0.001). However, there was no amputation event in either group. No difference in mortality was observed between groups (5.7% vs 9.1%, p=0.692).

CONCLUSION

Our preliminary findings suggest that local hospitals are capable of providing high-quality acute care to mass casualty burn victims. Our results suggest that patients with suspected limb ischemia should be rapidly transferred to a regional burn center to ensure optimal care. Systemic pre-planning such as employing telemedicine and personnel collaboration, should be considered by the administration to maximize the function of preliminary hospitals in burn care.

Clinical outcomes for minimally invasive primary and secondary orbital reconstruction using an advanced synergistic combination of navigation and endoscopy

BACKGROUND

Sequelae of inadequate orbital reconstruction include enophthalmos, hypoglobus, and diplopia. Accuracy of orbital reconstruction is largely subjective and especially difficult to achieve because of anatomic distortion in secondary or late reconstruction and in extensive injury. We combined computer navigation and endoscopy to perform accurate, aesthetic, and safe minimal-access primary and secondary orbital reconstruction.

METHODS

From 2013 to 2014, 24 patients underwent unilateral primary and secondary or late minimally invasive orbital reconstruction with mainly Medpor and/or titanium mesh by navigation and endoscopic assistance through transantral, transconjunctival, or upper blepharoplasty approaches. Mean follow-up was 13.8 months (range, 6.2 months to 2.8 years).

RESULTS

All orbital fractures were successfully reduced. Average enophthalmos among patients who underwent early reconstruction, late reconstruction, and multiorbital wall repair improved (p < .001) to 0.2 mm from 1.6, 2.6, and 2.6 mm, respectively. Hypoglobus and diplopia resolved in all. In early reconstruction patients, mean interorbital volume difference improved from 1.72 ± 0.87 to 0.53 ± 0.83 ml (P = .03). For late reconstruction patients, this difference improved from 3.41 ± 1.23 to 0.56 ± 0.96 ml (p < .001). There were no major complications during follow-up, and all were satisfied with their final appearance and function.

CONCLUSION

Navigation sharpens reconstructive accuracy and avoids injury to vital structures. Combined with endoscopic assistance for minimal-access reconstruction of wide-ranging orbital defects from primary to secondary or late cases and to extensive multiwall fractures, navigation facilitates minimal cosmetic incision and synergistic endoscope use and clearly optimizes aesthetic and functional outcomes, all with enhanced safety and unparalleled intraoperative visualization.

Surgical treatment of isolated zygomatic fracture: Outcome comparison between titanium plate and bioabsorbable plate

BACKGROUND

Zygoma fracture is of clinical importance because malar prominence plays an essential role in facial appearance. Traditionally, most maxillofacial surgeons perform osteosynthesis with titanium plates and screws for rigid fixation. However, this procedure has certain disadvantages that include the possibility of implant exposure, palpability or loosening of the screws, painful irritation, temperature sensitization, and radiographic artifacts. In this study, we compared the function and satisfaction outcome between Bonamates^® bioabsorbable implant and Leibinger titanium implant.

METHOD

Consecutively 53 patients with isolated unilateral zygomatic fracture that were treated with the Bonamates^® bioabsorbable plate system, n = 53 were compared to patients with the titanium plate system, n = 55 in the period between 2009 and 2013. All patients were followed-up at least 6 months. Preoperative and postoperative facial computed tomography (CT) scans were performed and scored from 0 to 2 in the 5 areas of zygoma. A score of 2 indicated the most severely displaced fracture in one of the areas. A visual analogue scale ranging from 0 to 10 was used to assess the postoperative aesthetic and functional satisfactions.

RESULT

The mean ages of the patients in the bioabsorbable and titanium plate groups were 33 years and 30 years, respectively. The male to female ratios were 1.2:1 (bioabsorbable plate group) and 1.1:1 (titanium plate group). The average preoperative CT scan scores of the bioabsorbable and titanium plate groups were 5.7 and 5.1, respectively. The postoperative CT scan scores of the bioabsorbable and titanium plate groups were 1.3 and 1.1, respectively. The implant cost of the bioabsorbable group was approximately 6-fold higher than that of the titanium plate group. The complication rate was similar in both groups and included complications such as palpable implant, skin irritation, and hypersensitive cheek. The patients in both groups attained similar mouth-opening function and a satisfactory score at 6 months after operation.

CONCLUSION

This study revealed that the bioabsorbable plate outcome was similar to the titanium plate outcome for patients with isolated unilateral zygomatic fracture. The bioabsorbable implant system provides another option for internal fixation devices in the treatment of zygomatic fractures and avoids implant removal surgery; however, the implant cost of bioabsorbable plates is higher than that of titanium plates in Taiwan.

Vorinostat enhances the cisplatin-mediated anticancer effects in small cell lung cancer cells

Background

Vorinostat, a histone deacetylase (HDAC) inhibitor, is a promising agent for cancer therapy. Combining vorinostat with cisplatin may relax the chromatin structure and facilitate the accessibility of cisplatin, thus enhancing its cytotoxicity. Studies have not yet investigated the effects of the combination of vorinostat and cisplatin on small cell lung cancer (SCLC).

Methods

We first assessed the efficacy of vorinostat with etoposide/cisplatin (EP; triple combination) and then investigated the effects of cotreatment with vorinostat and cisplatin on H209 and H146 SCLC cell lines. The anticancer effects of various combinations were determined in terms of cell viability, apoptosis, cell cycle distribution, and vorinostat-regulated proteins. We also evaluated the efficacy of vorinostat/cisplatin combination in H209 xenograft nude mice.

Results

Our data revealed that the triple combination engendered a significant reduction of cell viability and high apoptotic cell death. In addition, vorinostat combined with cisplatin enhanced cell growth inhibition, induced apoptosis, and promoted cell cycle arrest. We observed that the acetylation levels of histone H3 and α-tubulin were higher in combination treatments than in vorinostat treatment alone. Moreover, vorinostat reduced the expression of thymidylate synthase (TS), and TS remained inhibited after cotreament with cisplatin. Furthermore, an in vivo study revealed that the combination of vorinostat and cisplatin significantly inhibited tumor growth in xenograft nude mice (tumor growth inhibition T/C% = 20.5 %).

Conclusions

Combined treatments with vorinostat promote the cytotoxicity of cisplatin and induce the expression of vorinostat-regulated acetyl proteins, eventually enhancing antitumor effects in SCLC cell lines. Triple combinations with a low dosage of cisplatin demonstrate similar therapeutic effects. Such triple combinations, if applied clinically, may reduce the undesired adverse effects of cisplatin. The effects of the combination of vorinostat and cisplatin should be evaluated further before conducting clinical trials for SCLC treatment.

Measurements of the fast electron bremsstrahlung emission during electron cyclotron resonance heating in the HL-2A tokamak

A fast electron bremsstrahlung (FEB) diagnostic technique based on cadmium telluride (CdTe) detector has been developed recently in the HL-2A tokamak for measurements of the temporal evolution of FEB emission in the energy range of 10-200 keV. With a perpendicular viewing into the plasma on the equatorial plane, the hard x-ray spectra with eight different energy channels are measured. The discrimination of the spectra is implemented by an accurate spectrometry. The system also makes use of fast digitization and software signal processing technology. An ambient environment of neutrons, gammas, and magnetic disturbance requires careful shielding. During electron cyclotron resonance heating, the generation of fast electrons and the oscillations of electron fishbone (e-fishbone) have been found. Using the FEB measurement system, it has been experimentally identified that the mode strongly correlates with the electron cyclotron resonance heating produced fast electrons with 30-70 keV.

Observation of a spontaneous particle-transport barrier in the HL-2A tokamak

Using the profile analysis, the density perturbation transport analysis, and the Doppler reflectometry measurement, for the first time a spontaneous and steady-state particle-transport barrier has been evidenced in the Ohmic plasmas in the HL-2A tokamak with no externally applied momentum or particle input except the gas puffing. A threshold in density has been found for the observation of the barrier. The particle diffusivity is well-like, and the convection is found to be inward outside the well and outward inside the well. The formation of the barrier coincides with the transition between the trapped electron mode and the ion temperature gradient driven mode.

A method of particle transport study using supersonic molecular beam injection and microwave reflectometry on HL-2A tokamak

A method of the particle transport study using supersonic molecular beam injection (SMBI) and microwave reflectometry is reported in this paper. Experimental results confirm that pulsed SMBI is a good perturbation source with deeper penetration and better localization than the standard gas puffing. The local density modulation is induced using the pulsed SMBI and the perturbation density is measured by the microwave reflectometry. Using Fourier transform analysis for the local density perturbation, radial profiles of the amplitude and phase of the density modulation can be obtained. The experimental results in HL-2A show that the particle injected by SMBI is located at about r/a=0.65-0.75. The position of the main particle source can be determined through three aspects: the minimum of the phase of the first harmonic of the Fourier transform of the modulated density measured by microwave reflectometry; the H(a) intensity profile and the local density increase ratio. The maximum of the amplitude of the first harmonic shifts often inward relative to the particle source location, which indicates clearly there is an inward particle pinch in this area. Good agreement has been found between the experimental results and the simulation using analytical transport model. The particle diffusivity D and the particle convection velocity V have been obtained by doing this simulation. The sensitivity in the transport coefficients of the amplitude and the phase of the density modulation has been discussed.

A new soft x-ray pulse height analysis array in the HL-2A tokamak

A new soft x-ray pulse height analysis (PHA) array including nine independent subsystems, on basis of a nonconventional software multichannel analysis system and a silicon drift detector (SDD) linear array consisting of nine high performance SDD detectors, has been developed in the HL-2A tokamak. The use of SDD has greatly improved the measurement accuracy and the spatiotemporal resolutions of the soft x-ray PHA system. Since the ratio of peak to background counts obtained from the SDD PHA system is very high, p/b > or = 3000, the soft x-ray spectra measured by the SDD PHA system can approximatively be regarded as electron velocity distribution. The electron velocity distribution can be well derived in the pure ohmic and auxiliary heating discharges. The performance of the new soft x-ray PHA array and the first experimental results with some discussions are presented.

Measles: old vaccines, new vaccines

Isolation of measles virus in tissue culture by Enders and colleagues in the 1960s led to the development of the first measles vaccines. An inactivated vaccine provided only short-term protection and induced poor T cell responses and antibody that did not undergo affinity maturation. The response to this vaccine primed for atypical measles, a more severe form of measles, and was withdrawn. A live attenuated virus vaccine has been highly successful in protection from measles and in elimination of endemic measles virus transmission with the use of two doses. This vaccine is administered by injection between 9 and 15 months of age. Measles control would be facilitated if infants could be immunized at a younger age, if the vaccine were thermostable, and if delivery did not require a needle and syringe. To these ends, new vaccines are under development using macaques as an animal model and various combinations of the H, F, and N viral proteins. Promising studies have been reported using DNA vaccines, subunit vaccines, and virus-vectored vaccines.

Thirty-eight free fasciocutaneous flap transfers in acute burned-hand injuries

The benefits of free flap transfers in the acute burn injury are early wound closure, early mobility, reduced hospitalization, and possibly limb salvage. This retrospective study will attempt to provide principles to the use of free fasciocutaneous flap for the reconstruction of acute burned-hand injuries. Between 1995 and 2004, 5521 patients were admitted to the burn unit at Linkou Chang Gung Memorial Hospital. Of these, 38 patients (0.7%) patients received free fasciocutaneous flap transfers. Each patient's chart was reviewed the following data: age, gender, burn injury type, percentage of the burned area to total body surface area, flap type, operations prior to free flap coverage, the size and location of recipient area, timing of free flap coverage, operative time, duration of hospital stay, complications, flap survival and returning to work. All 38 free flaps survived and healed well. Three flaps with partial necrosis due to wound infections required subsequent debridement and skin grafting. Arterial thrombosis occurred in one patient and was salvaged successfully. Minimal donor-site morbidity with no intraoperative mortality was observed. Free fasciocutaneous flap transfer is a safe, efficacious one-stage reconstruction for acute burned-hands with satisfactory aesthetic and functional outcomes. Flap survival is not affected neither by the etiologies of burn nor the timing of free flap coverage.

Toroidal symmetry of the geodesic acoustic mode zonal flow in a tokamak plasma

The toroidal symmetry of the geodesic acoustic mode (GAM) zonal flows is identified with toroidally distributed three step Langmuir probes at the edge of the HuanLiuqi-2A (commonly referred to as HL-2A) tokamak plasmas for the first time. High coherence of both the GAM and the ambient turbulence for the toroidally displaced measurements along a magnetic field line is observed, in contrast with the high coherence of the GAM but low coherence of the ambient turbulence when the toroidally displaced measurements are not along the same field line. The radial and poloidal features of the flows are also simultaneously determined. The nonlinear three wave coupling between the high frequency turbulent fluctuations and the flows is demonstrated to be a plausible formation mechanism of the flows.

Phylogenetic analysis of classical swine fever virus in Taiwan

Two envelope glycoprotein (Erns and E2) regions of the classical swine fever virus (CSFV) were amplified by RT-PCR and sequenced directly from 158 specimens collected between 1989 and 2003 in Taiwan. Phylogenetic analysis of the two regions revealed a similar tree topology and the Erns region provided better discrimination than the E2 region. One hundred and fifteen isolates out of the 158 isolates were clustered within subgroup 2.1 (further classified as 2.1a and 2.1b) and 2.2, which were considered to be likely of the introduced strains, whereas the remaining 43 isolates were clustered within subgroup 3.4 and were considered to be of the endemic strains. The subgroup 2.1a viruses were first detected in 1994 and predominated from 1995 onwards. However, subgroup 3.4 viruses were prevalent in the early years, not being isolated after 1996. We have observed a dramatic switch in genotype from subgroup 3.4 to 2.1a. The subgroup 2.1a isolates are closely related to the Paderborn and Lao isolates, whereas 2.1b isolates have a close relationship to the Chinese Guangxi isolates. The phylogenetic tree of 27 CSFV sequences based on the complete envelope glycoprotein gene (Erns-E2) displayed better resolution than that based on the complete open reading frame.

Protective mechanisms induced by a Japanese encephalitis virus DNA vaccine: requirement for antibody but not CD8(+) cytotoxic T-cell responses

We have previously shown that a plasmid (pE) encoding the Japanese encephalitis virus (JEV) envelope (E) protein conferred a high level of protection against a lethal viral challenge. In the present study, we used adoptive transfer experiments and gene knockout mice to demonstrate that the DNA-induced E-specific antibody alone can confer protection in the absence of cytotoxic T-lymphocyte (CTL) functions. Plasmid pE administered by either intramuscular or gene gun injection produced significant E-specific antibodies, helper T (Th)-cell proliferative responses, and CTL activities. Animals receiving suboptimal DNA vaccination produced low titers of anti-E antibodies and were only partially or not protected from viral challenge, indicating a strong correlation between anti-E antibodies and the protective capacity. This observation was confirmed by adoptive transfer experiments. Intravenous transfer of E-specific antisera but not crude or T-cell-enriched immune splenocytes to sublethally irradiated hosts conferred protection against a lethal JEV challenge. Furthermore, experiments with gene knockout mice showed that DNA vaccination did not induce anti-E titers and protective immunity in Igmu(-/-) and I-Abeta(-/-) mice, whereas in CD8alpha(-/-) mice the pE-induced antibody titers and protective rate were comparable to those produced in the wild-type mice. Taken together, these results demonstrate that the anti-E antibody is the most critical protective component in this JEV challenge model and that production of anti-E antibody by pE DNA vaccine is dependent on the presence of CD4(+) T cells but independent of CD8(+) T cells.

Suppression of immune response and protective immunity to a Japanese encephalitis virus DNA vaccine by coadministration of an IL-12-expressing plasmid

IL-12 plays a central role in both innate and acquired immunity and has been demonstrated to potentiate the protective immunity in several experimental vaccines. However, in this study, we show that IL-12 can be detrimental to the immune responses elicited by a plasmid DNA vaccine. Coadministration of the IL-12-expressing plasmid (pIL-12) significantly suppressed the protective immunity elicited by a plasmid DNA vaccine (pE) encoding the envelope protein of Japanese encephalitis virus. This suppressive effect was associated with marked reduction of specific T cell proliferation and Ab responses. A single dose of pIL-12 treatment with plasmid pE in initial priming resulted in significant immune suppression to subsequent pE booster immunization. The pIL-12-mediated immune suppression was dose dependent and evident only when the IL-12 gene was injected either before or coincident with the pE DNA vaccine. Finally, using IFN-gamma gene-disrupted mice, we showed that the suppressive activity of the IL-12 plasmid was dependent upon endogenous production of IFN-gamma. These results demonstrate that coexpression of the IL-12 gene can sometimes produce untoward effects to immune responses, and thus its application as a vaccine adjuvant should be carefully evaluated.

Molecular epidemiological studies on foot-and-mouth disease type O Taiwan viruses from the 1997 epidemic

Sequence diversity was assessed of the complete VP1 gene directly amplified from 49 clinical specimens during an explosive foot-and-mouth disease (FMD) outbreak in Taiwan. Type O Taiwan FMD viruses are genetically highly homogenous, as seen by the minute divergence of 0.2-0.9% revealed in 20 variants. The O/HCP-0314/TW/97 and O/TCP-022/TW/97 viral variants dominated FMD outbreaks and were prevalent in most affected pig-raising areas. Comparison of deduced amino acid sequences around the main neutralizable antigenic sites on the VP1 polypeptide showed no significant antigenic variation. However, the O/CHP-158/TW/97 variant had an alternative critical residue at position 43 in antigenic site 3, which may be due to selective pressure in the field. Two vaccine production strains (O1/Manisa/Turkey/69 and O1/Campos/Brazil/71) probably provide partial heterologous protection of swine against O Taiwan viruses. The type O Taiwan variants clustered in sublineage A1 of four main lineages in the phylogenetic tree. The O/Hong Kong/9/94 and O/1685/Moscow/Russia/95 viruses in sublineage A2 are closely related to the O Taiwan variants. The causative agent for the 1997 epidemic presumably originated from a single common source of type O FMD viruses prevalent in neighboring areas.

Screening of protective antigens of Japanese encephalitis virus by DNA immunization: a comparative study with conventional viral vaccines

In this study, we evaluated the relative role of the structural and nonstructural proteins of the Japanese encephalitis virus (JEV) in inducing protective immunities and compared the results with those induced by the inactivated JEV vaccine. Several inbred and outbred mouse strains immunized with a plasmid (pE) encoding the JEV envelope protein elicited a high level of protection against a lethal JEV challenge similar to that achieved by the inactivated vaccine, whereas all the other genes tested, including those encoding the capsid protein and the nonstructural proteins NS1-2A, NS3, and NS5, were ineffective. Moreover, plasmid pE delivered by intramuscular or gene gun injections produced much stronger and longer-lasting JEV envelope-specific antibody responses than immunization of mice with the inactivated JEV vaccine did. Interestingly, intramuscular immunization of plasmid pE generated high-avidity antienvelope antibodies predominated by the immunoglobulin G2a (IgG2a) isotype similar to a sublethal live virus immunization, while gene gun DNA immunization and inactivated JEV vaccination produced antienvelope antibodies of significantly lower avidity accompanied by a higher IgG1-to-IgG2a ratio. Taken together, these results demonstrate that the JEV envelope protein represents the most critical antigen in providing protective immunity.

Modulation of immune responses to DNA vaccines by codelivery of cytokine genes

DNA vaccines containing genes for antigenic portions of viruses have recently been developed as a novel vaccination technology. Direct injection of plasmid DNA in vivo results in prolonged expression of viral proteins and may, thus, mimic the action of attenuated vaccines. An important advantage of this vaccination method is that in vivo-synthesized viral proteins can enter both major histocompatibility complex (MHC) class I and class II antigen-processing pathways to activate specific immunization. In many animal models for infectious diseases, DNA vaccines induced a broad range of immune responses, including antibody, CD8+ cytotoxic T lymphocytes (CTL) and CD4+ helper T (Th) lymphocyte responses, and protective immunity against challenge with the pathogen. The magnitude and nature of these immune responses to DNA vaccines can be further manipulated by codelivery of cytokine genes. Summarizing the many studies reported to date, we can draw conclusions regarding the adjuvant effects of these cytokine genes on DNA vaccines. Coadministration of granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin (IL)-2 genes induces higher antibody titers and T-cell proliferation responses than other cytokine genes tested to date. In contrast, the CTL activity is only modestly increased by the GM-CSF and IL-2 genes. The IL-12 gene polarizes the immune responses to DNA vaccines toward Th1 cell development and stimulates the strongest CTL activity. In contrast, co-injection of the IL-4 gene promotes the development of Th2 cells and increases production of antibodies, but suppresses CTL activity. Thus, the immune responses to DNA vaccines can be engineered by co-injection of an appropriate cytokine gene to favor the formation of either CTL or neutralization antibodies and, therefore, provide the best protection against a particular pathogen.

Purification of chitinolytic protein from Rehmannia glutinosa showing N-terminal amino acid sequence similarity to thaumatin-like proteins

We have purified a 21-kDa protein, designated as P1, from Rehmannia glutinosa to homogeneity by ammonium sulfate precipitation, anion exchange chromatography, hydrophobic interaction chromatography, and preparative native PAGE. The purified P1 had chitin degradation activity. The N-terminal amino acid sequence of P1 indicated that it is very similar to those of thaumatin and other reported thaumatin-like proteins.

Isolation of efficient antivirals: genetic suppressor elements against HIV-1

The development of general approaches for the isolation of efficient antivirals and the identification and validation of targets for drug screening are becoming increasingly important, due to the emergence of previously unrecognized viral diseases. The genetic suppressor element (GSE) technology is an approach based on the functional expression selection of efficient genetic inhibitors from random fragment libraries derived from a gene or genome of interest. We have applied this technology to isolate potent genetic inhibitors against HIV-1. Two strategies were used to select for GSEs that interfere with latent virus induction and productive HIV-1 infection based on the expression of intracellular and surface antigens. The selected GSEs clustered in seven narrowly defined regions of the HIV-1 genome and were found to be functionally active. These elements are potential candidates for the gene therapy of AIDS. The developed approaches can be applied to other viral pathogens, as well as for the identification of cellular genes supporting the HIV-1 life cycle.

Establishment and characterization of NS3 protein-specific T-cell clones from a patient with chronic hepatitis C

Our previous study showed dominant proliferative response of peripheral mononuclear cells to hepatitis C virus (HCV) nonstructural (NS-3) (T9, from aa 1188 to 1493) in chronically infected patients. Six T9-specific T-cell clones derived in an HCV patient were established and studied for the antigen specificity and the ability of augmentation of in vitro antibody production. All these cloned T-cell lines responded exclusively to T9 antigen and could help autologous B cells in producing anti-T9 antibody in vitro. Cytokine mRNAs of these T cells was detected by polymerase chain reaction and predominant IL-2 and IFN-gamma production was noted. In addition, further elucidation of T-cell antigenic determinant and MHC restriction suggested that these T-cell clones recognized at least two different T-cell antigenic determinants within the NS-3 region in an HLA DQ2-restricted manner. We believe characterization of HCV-specific T-cell responses, especially T-cell epitope mapping and cytokine production pattern, may shed light on further understanding the pathogenic mechanism and designing therapy for HCV infection.

Transforming growth factor beta stabilizes p15INK4B protein, increases p15INK4B-cdk4 complexes, and inhibits cyclin D1-cdk4 association in human mammary epithelial cells

The effects of transforming growth factor beta (TGF-beta) were studied in closely related human mammary epithelial cells (HMEC), both finite-life-span 184 cells and immortal derivatives, 184A1S, and 184A1L5R, which differ in their cell cycle responses to TGF-beta but express type I and type II TGF-beta receptors and retain TGF-beta induction of extracellular matrix. The arrest-resistant phenotype was not due to loss of cyclin-dependent kinase (cdk) inhibitors. TGF-beta was shown to regulate p15INK4B expression at at least two levels: mRNA accumulation and protein stability. In TGF-beta-arrested HMEC, there was not only an increase in p15 mRNA but also a major increase in p5INK4B protein stability. As cdk4- and cdk6-associated p15INK4B increased during TGF-beta arrest of sensitive cells, there was a loss of cyclin D1, p21Cip1, and p27Kip1 from these kinase complexes, and cyclin E-cdk2-associated p27Kip1 increased. In HMEC, p15INK4B complexes did not contain detectable cyclin. p15INK4B from both sensitive and resistant cells could displace in vitro cyclin D1, p21Cip1, and p27Kip1 from cdk4 isolated from sensitive cells. Cyclin D1 could not be displaced from cdk4 in the resistant 184A1L5R cell lysates. Thus, in TGF-beta arrest, p15INK4B may displace already associated cyclin D1 from cdks and prevent new cyclin D1-cdk complexes from forming. Furthermore, p27Kip1 binding shifts from cdk4 to cyclin E-cdk2 during TGF-beta-mediated arrest. The importance of posttranslational regulation of p15INK4B by TGF-beta is underlined by the observation that in TGF-beta-resistant 184A1L5R, although the p15 transcript increased, p15INK4B protein was not stabilized and did not accumulate, and cyclin D1-cdk association and kinase activation were not inhibited.

Expression of two cDNAs encoding class I chitinases of rice in Escherichia coli

Two cDNAs encoding class I chitinases of rice were expressed in Escherichia coli. The cDNAs were fused to the MS2-polymerase gene in an expression vector, pEx31. The fusion proteins, expressed under the control of the lambda PL-promoter, showed the chitinase activity independent of the existence of the hevein domain. The enzymatic hydrolysis of colloidal chitin by the fusion proteins showed that the proteins were endo-type enzymes.

Alcaligenes xylosoxidans neonatal meningitis: a case report

Neonatal meningitis caused by Alcaligenes xylosoxidans is associated with a high mortality rate. The causative microorganism is resistant to most antimicrobials. Generally, once the organism has been isolated from the cerebrospinal fluid of the infected neonate, initial therapy with a third-generation cephalosporin and trimethoprim-sulfamethoxazole is recommended before determining its susceptibility to antimicrobials. There present this is the first of neonatal meningitis with transient diabetes insipidus cause by A. xylosoxidans. The patient was treated with dDAVP for seven days and a combination of imipenem plus trimethoprim-sulfamethoxazole for 28 days. The patient was discharged in a stable condition and the end of that time, but with sequelae of hydrocephalus and hearing impairment.

A novel inhibitor of cyclin-Cdk activity detected in transforming growth factor beta-arrested epithelial cells

Transforming growth factor beta (TGF-beta) is a potent inhibitor of epithelial cell growth. Cyclins E and A in association with Cdk2 have been shown to play a role in the G1-to-S phase transition in mammalian cells. We have studied the effects of TGF-beta-mediated growth arrest on G1/S cyclins E and A. Inhibition of cyclin A-associated kinase by TGF-beta is primarily due to a decrease in cyclin A mRNA and protein. By contrast, while TGF-beta inhibits accumulation of cyclin E mRNA, the reduction in cyclin E protein is minimal. Instead, we find that the activation of cyclin E-associated kinase that normally accompanies the G1-to-S phase transition is inhibited. A novel inhibitor of cyclin-Cdk complexes was detected in TGF-beta-treated cell lysates. Inhibition is mediated by a heat-stable protein that targets both Cdk2 and Cdc2 kinases. In G0-arrested cells, a similar inhibitor of Cdk2 kinase was detected. These data suggest the existence of an inhibitor of cyclin-dependent kinases induced under different conditions to mediate antiproliferative responses.

Blockage of EGF receptor signal transduction causes reversible arrest of normal and immortal human mammary epithelial cells with synchronous reentry into the cell cycle

We demonstrate that blockage of EGF receptor signal transduction is sufficient by itself to cause a rapid, efficient, and reversible G0-like growth arrest of normal human mammary epithelial cells (HMEC) of finite lifespan as well as two immortally transformed cell lines derived from normal HMEC following in vitro transformation with benzo[a]pyrene. For normal HMEC, the significant level of endogenous production of TGF alpha requires utilization of blocking antibodies to the EGF receptor to achieve cessation of growth in mass culture, whereas removal of EGF is sufficient to arrest the immortal cell lines. In the growth-arrested cells, protein synthesis remains depressed; reexposure to EGF leads to a rapid increase in protein synthesis. Inhibition of DNA synthesis is not detectable until approximately 12 h after removal of EGF/TGF alpha and is pronounced by 24 h. Reexposure to EGF produces high levels of synthesis of the early response genes, c-myc, c-fos, c-jun, and MGSA, within 1 h. DNA synthesis increases only after 10 h, with a sharp peak after 15-20 h. Reexposure of the growth-arrested normal HMEC for 1 h with EGF allows a majority of the cells capable of cycling to subsequently enter the S phase. Little is currently known about cell cycle control in normal human epithelial cells. The efficient and gentle method of achieving reversible G0 growth arrest reported here may facilitate studies on the cell cycle of this cell type. Additionally, results from normal HMEC can be compared with those from syngeneic immortalized cell populations to determine possible cell cycle parameters altered as a result of immortal transformation.

The skin, tongue, and brain as favorable organs for hog cholera diagnosis by immunofluorescence

Hog cholera virus antigens were found densely distributed in skin and tongue of pigs experimentally infected with hog cholera virus. The finding described here warrants the usage of ear biopsies for hog cholera diagnosis on a herd basis.

[Clinical investigation by transcranial Doppler sonography of the effect of norepinephrine on cerebral arterial blood velocity of normotensive males]

Transcranial Doppler (TCD) sonography is a new, non-invasive method for evaluation of the hemodynamics of cerebral circulation. Using a 2-MHz probe, the intracranial middle, posterior, vertebral and basilar arteries can be isolated easily to obtain parameters of systolic, diastolic, mean velocities and pulsatility index (PI). Changes of blood velocities and PI can assist evaluation of the condition of intracranial arterial spasm, dilatation and cerebral vascular resistance. The purpose of this study is to evaluate the hemodynamic effect of norepinephrine (NE) on cerebral circulation. Eighteen normotensive male healthy volunteers (mean age 42 years) were studied with TCD before and during NE infusion (13-16 micrograms/min). Results showed that systolic, diastolic and mean arterial pressure were increased significantly during NE infusion. Blood velocities of middle, posterior, vertebral and basilar arteries also increased markedly. Increased cerebral vascular resistance with elevation of PI was also noted in all of the persons studied. These findings provide evidence that NE infusion induces intracerebral vasospasm.

[Brainstem auditory evoked potentials in diabetes mellitus]

It is well-known that diabetic patients develop peripheral and autonomic neuropathy, and recent review has also suggested the occurrence of central pathway abnormality in diabetics. In this article, we conducted the BAEP study on 61 cases of NIDDM and 11 cases of IDDM. Peak latency, interpeak latency (IPL) and peak amplitude of BAEPs were analyzed in each case. For further correlation, the motor and sensory nerve conduction velocities of median nerve, the blood sugar, the serum HbA1c were measured. Two nondiabetic groups, age and sex matched with NIDDM and IDDM groups, were used as control. In NIDDM group, the results showed prolongation of all peak latency and IPL except peak latency of wave II and wave IV in the left side and bilateral IPL III-V. There was no statistically significant amplitude difference between NIDDM and age-matched control group. The result of IDDM group revealed prolongation of all peak latency and IPL, except the right IPL III-V. As for amplitude, waves III and V in the right side and waves I and V in the left side were reduced as compared with the age-matched young control group. There was no statistically significant difference in all peak latencies and IPLs between NIDDM and IDDM groups. In both groups of NIDDM and IDDM, the MNCV and SNCV of median nerve were significantly delayed in conduction. The prolongation of III and V peak latency had a linear correlation with their amplitude reduction. In conclusion, both peripheral and central conduction dysfunction occur in both IDDM and NIDDM patients.

[Plasma levels of atrial natriuretic factor (ANF) in the stroke patients after glycerol and mannitol infusion]

This study included 43 patients with stroke in a range of 48 to 85 years of age. Among them, 24 were male and 19 were female. Changes in blood pressure, plasma ANF (by radioimmunoassay), serum sodium, and serum osmolarity before and 40 minutes after hyperosmotic agents infusion were studied. The stroke was classified to be putaminal hemorrhage in 12 cases, thalamic hemorrhage in 5 cases, putaminothalamic hemorrhage in 2 cases, lobar hematoma in 2 cases, cerebral infarction in 20 cases and brainstem ischemic stroke in 2 cases. Twenty-nine patients received glycerol and the other fourteen received mannitol. After glycerol or mannitol infusion, the plasma ANF raised significantly (P less than 0.05, paired Student's test), also the serum osmolarity (P less than 0.05, paired Student's t test), but the blood pressure and serum sodium kept unchanged. Either before or after the hyperosmotic agents, no significant difference in plasma ANF was noted between the hemorrhagic and infarction patients, between the right and the left hemispheric stroke, or between male and female patients. We did not observe age-related (less than 65 or greater than 65 years) difference in plasma ANF concentration in this study, either.

Thymolipoma in patients with myasthenia gravis: report of two cases and review

Two cases of simultaneous occurrence of myasthenia gravis (MG) and thymolipoma are described and 4 previously reported cases are reviewed. In all 6 cases, thymectomy was performed. Pre- and postoperatively, the clinical status of the patients was similar to that of late-onset MG without thymolipoma. It is possible that simultaneous occurrence of MG and thymolipoma may be coincidental.

Actinoidin A2, a novel glycopeptide: production, preparative HPLC separation and characterization

An unidentified Nocardia sp. (SK&F-AAJ-193) was isolated and found to produce actinoidin A and a novel analog which we have named actinoidin A2. This new glycopeptide antibiotic differs from actinoidin A by the presence of rhamnose instead of acosamine. This analog was isolated using Dianion HP-20 resin followed by a specific glycopeptide affinity column (Affigel-10-D-Ala-D-Ala). The purification was accomplished using preparative ion-pairing chromatography. Actinoidin A2 is active against Staphylococcus aureus and coagulase-negative Staphylococci although it is less potent than actinoidin A.

Kibdelins, novel glycopeptide antibiotics. I. Discovery, production, and biological evaluation

A new subspecies of Kibdelosporangium aridum subsp. largum (SK&F AAD-609), was isolated and shown to produce novel glycopeptides related to aridicins, but containing a homologous series of glycolipids based on N-acylglucosamine. These compounds showed improvements over the aridicins in in vitro activity and were effective in mouse protection studies against a range of Gram-positive bacteria, including methicillin resistant staphylococci. Pharmacokinetic studies indicated that they have high serum concentrations and long-acting potential. The kibdelin complex modified rumen metabolism in a manner favorable for growth promotion.