INX-315, a Selective CDK2 Inhibitor, Induces Cell Cycle Arrest and Senescence in Solid Tumors

Cyclin-dependent kinase 2 (CDK2) is thought to play an important role in driving proliferation of certain cancers, including those harboring CCNE1 amplification and breast cancers that have acquired resistance to CDK4/6 inhibitors (CDK4/6i). The precise impact of pharmacologic inhibition of CDK2 is not known due to the lack of selective CDK2 inhibitors. Here we describe INX-315, a novel and potent CDK2 inhibitor with high selectivity over other CDK family members. Using cell-based assays, patient-derived xenografts (PDX), and transgenic mouse models, we show that INX-315 (i) promotes retinoblastoma protein hypophosphorylation and therapy-induced senescence (TIS) in CCNE1-amplified tumors, leading to durable control of tumor growth; (ii) overcomes breast cancer resistance to CDK4/6i, restoring cell cycle control while reinstating the chromatin architecture of CDK4/6i-induced TIS; and (iii) delays the onset of CDK4/6i resistance in breast cancer by driving deeper suppression of E2F targets. Our results support the clinical development of selective CDK2 inhibitors.

SIGNIFICANCE

INX-315 is a novel, selective inhibitor of CDK2. Our preclinical studies demonstrate activity for INX-315 in both CCNE1-amplified cancers and CDK4/6i-resistant breast cancer. In each case, CDK2 inhibition induces cell cycle arrest and a phenotype resembling cellular senescence. Our data support the development of selective CDK2 inhibitors in clinical trials. See related commentary by Watts and Spencer, p. 386. This article is featured in Selected Articles from This Issue, p. 384.

Increased psychological distress among young people before and during the fifth wave of COVID-19 after two years of pandemic in Hong Kong: a 6-month longitudinal study

BACKGROUND

Despite over two years of COVID-19 worldwide, the outbreak of the Omicron variant has given rise to an unprecedented surge of infection with diverse lockdown measures implemented globally. Whether the emergence of a new wave of COVID-19 could further affect mental health in the population after nearly two years of the pandemic remains to be addressed. Furthermore, whether changes in smartphone overuse behaviours and physical activity - both of which are particularly relevant to young people - would together contribute to changes in distress symptoms during this wave of COVID-19 was also examined.

METHODS

A total of 248 young people from an ongoing household-based epidemiological study in Hong Kong who completed their baseline assessments prior to the Omicron variant outbreak, i.e., fifth wave of COVID-19 (July-November 2021), were invited for a 6-month follow-up study during this wave of infection (January-April 2022) (mean age = 19.7 years, SD = 2.7; 58.9% females). At both time points, levels of global distress symptoms, perceived stress, smartphone overuse, frequency of engagement in vigorous physical activity, and other potential risk and protective factors were assessed.

RESULTS

The proportion of young people presenting moderate-to-severe distress (6-item Kessler Psychological Distress Scale ≥ 5) significantly increased from 45.6 to 54.4% during the fifth wave of COVID-19 (p < 0.010). Significantly increased levels of smartphone overuse and reduced days of vigorous physical activity were also observed during the fifth wave. Notably, increased smartphone overuse and reduced physical activity both additively and interactively contributed to elevated distress at 6 months, even after accounting for demographic characteristics, psychiatric history, childhood adversity, as well as baseline distress symptoms, resilience, and recent personal stressors.

CONCLUSIONS

The findings suggest that the emergence of a new wave of COVID-19, specifically the Omicron outbreak, can further aggravate mental distress even after a protracted period of the pandemic. Awareness of the dynamic nature of COVID-19 is necessitated to address the pressing mental health needs of populations. Supporting young people in healthier patterns of smartphone use and physical activity can be helpful.

Prevalence of frequent nightmares and their prospective associations with 1-year psychiatric symptoms and disorders and functioning in young adults: a large-scale epidemiological study in Hong Kong

Study Objectives

No study has yet examined the prevalence of frequent nightmares in representative youth populations in Asia and how they may contribute to future mental health risks. We aimed to fill this gap using data from a large-scale household-based youth sample in Hong Kong.

Methods

Participants were consecutively recruited from a large-scale epidemiological youth mental health study in Hong Kong (n=3,132). A subset of participants were invited for a follow-up assessment after 1 year (n=1,154 in the final analyses). Frequent nightmares (≥1/week during the past month) were assessed using an item from the Pittsburgh Sleep Quality Index. Univariate analyses and multivariable logistic regression models were applied to examine the contribution of frequent nightmares at baseline to moderate-to-severe depressive and anxiety symptoms, post-traumatic stress disorder symptoms, and 30-day major depressive episode (MDE) or generalised anxiety disorder (GAD), both at baseline and follow-up. The long-term functional implications of frequent nightmares were also examined.

Results

The prevalence of frequent nightmares was 16.3%. Females were more likely to experience frequent nightmares (20.4%) compared to males (12.1%), p&lt;0.001. Baseline frequent nightmares were significantly associated with all four mental health outcomes at 1 year. Notably, their prospective associations with depressive and anxiety symptoms and 30-day MDE/GAD remained significant even after adjusting for external stressors, resilience, and sociodemographic characteristics. Frequent nightmares were also significantly associated with both current and 1-year functional impairments.

Conclusions

Frequent nightmares have significant long-term implications on mental health and functioning. Identifying young adults with frequent nightmares can improve early risk detection and intervention in the population.

Impact of smartphone overuse on 1-year severe depressive symptoms and momentary negative affect: Longitudinal and experience sampling findings from a representative epidemiological youth sample in Hong Kong

Smartphone overuse can have detrimental impacts on youth mental health. How it may be longitudinally associated with depressive symptoms and functioning, and with daily momentary affect, remains to be investigated. A total of 3,033 young people were consecutively recruited from a large-scale epidemiological youth mental health study in Hong Kong. A subsample (n = 936) was followed-up after 1 year, with experience sampling data collected from 177 participants. Separate multivariable logistic regression models were applied to examine the prospective associations between smartphone overuse and depressive symptoms, with multilevel models fitted to examine its associations with momentary affect. The prevalence of smartphone overuse in the Hong Kong youth population was 29.3%. Smartphone overuse was significantly associated with more depressive symptoms and functional impairments both cross-sectionally and longitudinally. The associations between smartphone overuse and 1-year depressive symptoms were significant, even when accounting for baseline symptoms, social media use, and other risk and protective factors. Baseline depressive symptoms, in contrast, were not associated with 1-year smartphone overuse after adjusting for baseline smartphone overuse. Smartphone overuse was also significantly associated with higher levels of momentary negative affect, even when accounting for depressive symptoms. Strategies to mitigate the impact of smartphone overuse can have important long-term implications.

Cystathionine-β-synthase is essential for AKT-induced senescence and suppresses the development of gastric cancers with PI3K/AKT activation

Hyperactivation of oncogenic pathways downstream of RAS and PI3K/AKT in normal cells induces a senescence-like phenotype that acts as a tumor-suppressive mechanism that must be overcome during transformation. We previously demonstrated that AKT-induced senescence (AIS) is associated with profound transcriptional and metabolic changes. Here, we demonstrate that human fibroblasts undergoing AIS display upregulated cystathionine-β-synthase (CBS) expression and enhanced uptake of exogenous cysteine, which lead to increased hydrogen sulfide (H₂S) and glutathione (GSH) production, consequently protecting senescent cells from oxidative stress-induced cell death. CBS depletion allows AIS cells to escape senescence and re-enter the cell cycle, indicating the importance of CBS activity in maintaining AIS. Mechanistically, we show this restoration of proliferation is mediated through suppressing mitochondrial respiration and reactive oxygen species (ROS) production by reducing mitochondrial localized CBS while retaining antioxidant capacity of transsulfuration pathway. These findings implicate a potential tumor-suppressive role for CBS in cells with aberrant PI3K/AKT pathway activation. Consistent with this concept, in human gastric cancer cells with activated PI3K/AKT signaling, we demonstrate that CBS expression is suppressed due to promoter hypermethylation. CBS loss cooperates with activated PI3K/AKT signaling in promoting anchorage-independent growth of gastric epithelial cells, while CBS restoration suppresses the growth of gastric tumors in vivo. Taken together, we find that CBS is a novel regulator of AIS and a potential tumor suppressor in PI3K/AKT-driven gastric cancers, providing a new exploitable metabolic vulnerability in these cancers.

Ribosomal proteins and human diseases: molecular mechanisms and targeted therapy

Ribosome biogenesis and protein synthesis are fundamental rate-limiting steps for cell growth and proliferation. The ribosomal proteins (RPs), comprising the structural parts of the ribosome, are essential for ribosome assembly and function. In addition to their canonical ribosomal functions, multiple RPs have extra-ribosomal functions including activation of p53-dependent or p53-independent pathways in response to stress, resulting in cell cycle arrest and apoptosis. Defects in ribosome biogenesis, translation, and the functions of individual RPs, including mutations in RPs have been linked to a diverse range of human congenital disorders termed ribosomopathies. Ribosomopathies are characterized by tissue-specific phenotypic abnormalities and higher cancer risk later in life. Recent discoveries of somatic mutations in RPs in multiple tumor types reinforce the connections between ribosomal defects and cancer. In this article, we review the most recent advances in understanding the molecular consequences of RP mutations and ribosomal defects in ribosomopathies and cancer. We particularly discuss the molecular basis of the transition from hypo- to hyper-proliferation in ribosomopathies with elevated cancer risk, a paradox termed "Dameshek's riddle." Furthermore, we review the current treatments for ribosomopathies and prospective therapies targeting ribosomal defects. We also highlight recent advances in ribosome stress-based cancer therapeutics. Importantly, insights into the mechanisms of resistance to therapies targeting ribosome biogenesis bring new perspectives into the molecular basis of cancer susceptibility in ribosomopathies and new clinical implications for cancer therapy.

Reprogrammed mRNA translation drives resistance to therapeutic targeting of ribosome biogenesis

Elevated ribosome biogenesis in oncogene‐driven cancers is commonly targeted by DNA‐damaging cytotoxic drugs. Our previous first‐in‐human trial of CX‐5461, a novel, less genotoxic agent that specifically inhibits ribosome biogenesis via suppression of RNA polymerase I (Pol I) transcription, revealed single‐agent efficacy in refractory blood cancers. Despite this clinical response, patients were not cured. In parallel, we demonstrated a marked improvement in the in vivo efficacy of CX‐5461 in combination with PI3K/AKT/mTORC1 pathway inhibitors. Here, we reveal the molecular basis for this improved efficacy observed in vivo, which is associated with specific suppression of translation of mRNAs encoding regulators of cellular metabolism. Importantly, acquired resistance to this cotreatment is driven by translational rewiring that results in dysregulated cellular metabolism and induction of a cAMP‐dependent pathway critical for the survival of blood cancers including lymphoma and acute myeloid leukemia. Our studies thus identify key molecular mechanisms underpinning the response of blood cancers to selective inhibition of ribosome biogenesis and define metabolic vulnerabilities that will facilitate the rational design of more effective regimens for Pol I‐directed therapies.

Abstract PR13: Inhibition of RNA polymerase I transcription activates targeted DNA damage response and enhances the efficacy of PARP inhibitors in high-grade serous ovarian cancer

Introduction: PARP inhibitors (PARPi) have revolutionized disease management of patients with homologous recombination (HR) DNA repair-deficient high-grade serous ovarian cancer (HGSOC). However, acquired resistance to PARPi is a major challenge in the clinic. The specific inhibitor of RNA polymerase I (Pol I) transcription of ribosomal RNA genes (rDNA) has demonstrated single-agent antitumor activity in p53 wild-type and p53-mutant hematologic malignancies (first-in-human trial, dose escalation study of CX-5461 at Peter MacCallum Cancer Centre) (Khot et al., Cancer Discov 2019). CX-5461 has also been reported to exhibit synthetic lethality with BRCA1/2 deficiency through stabilization of G-quadruplex DNA (GQ) structures. Here, we investigate the efficacy of CX-5461 in treating HGSOC.

Experimental Design: The mechanisms by which CX-5461 induces DNA damage response (DDR) and displays synthetic lethality in HR-deficient HGSOC cells are explored. We present in vivo data of mice bearing two functionally and genomically profiled HGSOC-patient-derived xenograft (PDX)s treated with CX-5461 and olaparib, alone and in combination. We also investigate CX-5461-sensitivity gene expression signatures in primary and relapsed HGSOC.

Results: Utilizing ovarian cancer cell lines, we demonstrate that sensitivity to CX-5461 is associated with “BRCA1 mutation” and “MYC targets” gene expression signatures. In addition, sensitivity to CX-5461 is associated with high basal rates of Pol I transcription. Importantly, we demonstrate a novel mechanism for CX-5461 synthetic lethal interaction with HR deficiency mediated through the induction of replication stress at rDNA repeats. Our data reveal CX-5461-mediated DDR in HR-deficient cells does not involve stabilization of GQ structures as previously proposed. On the contrary, we show definitively that CX-5461 inhibits Pol I recruitment leading to rDNA chromatin defects including stabilization of R-loops, single-stranded DNA, and replication stress at the rDNA. Mechanistically, we demonstrate CX-5461 leads to replication-dependent DNA damage involving MRE11-dependent degradation of replication forks. Importantly, CX-5461 has a different sensitivity spectrum to olaparib and cooperates with PARPi in exacerbating replication stress, leading to enhanced therapeutic efficacy in HR-deficient HGSOC-PDX in vivo compared to single-agent treatment of both drugs. Further, CX-5461 exhibits single-agent efficacy in olaparib-resistant HGSOC-PDX overcoming PARPi-resistance mechanisms involving fork protection. Importantly, we identify CX-5461-sensitivity gene expression signatures in primary and relapsed HGSOC.

Conclusions: CX-5461 is a promising therapy alone and in combination therapy with PARPi in HR-deficient HGSOC. CX-5461 also has exciting potential as a treatment option for patients with relapsed HGSOC tumors that have high MYC activity and poor clinical outcome; these patients currently have very limited effective treatment options.

This abstract is also being presented as Poster A71.

Citation Format: Elaine Sanij, Katherine Hannan, Jiachen Xuan, Shunfei Yan, Jessica A. Ahern, Anna S. Trigos, Natalie Brajanovski, Jinbae Son, Keefe T. Chan, Olga Kondrashova, Elizabeth Lieschke, Matthew J. Wakefield, Sarah Ellis, Carleen Cullinane, Gretchen Poortinga, Kum Kum Khanna, Linda Mileshkin, Grant A. McArthur, John Soong, Els M. Berns, Ross D. Hannan, Clare L. Scott, Karen E. Sheppard, Richard B. Pearson. Inhibition of RNA polymerase I transcription activates targeted DNA damage response and enhances the efficacy of PARP inhibitors in high-grade serous ovarian cancer [abstract]. In: Proceedings of the AACR Special Conference on Advances in Ovarian Cancer Research; 2019 Sep 13-16, 2019; Atlanta, GA. Philadelphia (PA): AACR; Clin Cancer Res 2020;26(13_Suppl):Abstract nr PR13.

CX-5461 activates the DNA damage response and demonstrates therapeutic efficacy in high-grade serous ovarian cancer

Acquired resistance to PARP inhibitors (PARPi) is a major challenge for the clinical management of high grade serous ovarian cancer (HGSOC). Here, we demonstrate CX-5461, the first-in-class inhibitor of RNA polymerase I transcription of ribosomal RNA genes (rDNA), induces replication stress and activates the DNA damage response. CX-5461 co-operates with PARPi in exacerbating replication stress and enhances therapeutic efficacy against homologous recombination (HR) DNA repair-deficient HGSOC-patient-derived xenograft (PDX) in vivo. We demonstrate CX-5461 has a different sensitivity spectrum to PARPi involving MRE11-dependent degradation of replication forks. Importantly, CX-5461 exhibits in vivo single agent efficacy in a HGSOC-PDX with reduced sensitivity to PARPi by overcoming replication fork protection. Further, we identify CX-5461-sensitivity gene expression signatures in primary and relapsed HGSOC. We propose CX-5461 is a promising therapy in combination with PARPi in HR-deficient HGSOC and also as a single agent for the treatment of relapsed disease.

Oncogene-induced senescence: From biology to therapy

Oncogene-induced senescence (OIS) is a powerful intrinsic tumor-suppressive mechanism, arresting cell cycle progression upon oncogene-activating genomic alterations. The discovery and characterization of the senescence-associated secretome unveiled a rich additional complexity to the senescence phenotype, including extrinsic impacts on the microenvironment and engagement of the immune response. Emerging evidence suggests that senescence phenotypes vary depending on the oncogenic stimulus. Therefore, understanding the mechanisms underlying OIS and how they are subverted in cancer will provide invaluable opportunities to identify alternative strategies for treating oncogene-driven cancers. In this review, we primarily discuss the key mechanisms governing OIS driven by the RAS/MAPK and PI3K/AKT pathways and how understanding the biology of senescent cells has uncovered new therapeutic possibilities to target cancer.

224 Malignancy associated pericardial effusion- do we need to drain them all?

On Behalf

Cardiac Team, Department of Medicine, Queen Elizabeth Hospital

Background

Management of significant pericardial effusion in cancer patients is controversial. These patients have poor prognosis, and avoiding unnecessary intervention is important. Close monitoring of symptoms and echocardiogram is often a reasonable option, but inherits risk of cardiac tamponade. Whether pericardial drainage by means of percutaneous pericardiocentesis or surgical pericardiotomy could prevent future deterioration or affect survival is unknown.

Purpose

To evaluate the benefit of elective pericardial drainage in malignancy associated pericardial effusion without echocardiographic or clinical evidence of tamponade effect.

Methods

From 1st Jul 2014 to 31st Dec 2017, all patients with new onset malignancy-associated pericardial effusion with size more than 1cm were retrospectively analyzed. Patients with clinical or echocardiographic evidence of cardiac tamponade were excluded. We compared pericardial drainage versus monitoring for short-term (30-day), mid-term (90-day) and long term (1 year) survival without need for drainage.

Results

101 patients were retrospectively analyzed. 40 (39.6%) patients underwent drainage. Overall median survival free from drainage was 4 months. There were no significant difference in short-term (30-day), mid-term (90-day) and long term (1-year) survival free from drainage or mortality between treatment and monitoring group. Size of pericardial effusion did not predict mortality or future need of drainage. Chemotherapy was associated with improved 30-day mortality (RR 0.53 CI 0.32-0.87 p = 0.025) but not survival free from drainage or longer term mortality.

Conclusion

Close monitoring could be a feasible strategy in cancer patients with significant pericardial effusion without tamponade effect.

Baseline characteristics Factor Drainage (n = 40) monitoring (n = 61) p-value method of drainage pericardiocentesis alone 17 NA pericardiotomy alone 13 both 10 Male 19 (47.5%) 27 (44.3%) 0.749 mean size (cm) 1.93 2.77 &lt;0.001 mean age 60.9 63.1 0.357 on chemotherapy 27 (67.5%) 38 (62.3%) 0.593

Abstract 224 Figure. Survival free from drainage

A functional genetic screen defines the AKT-induced senescence signaling network

Exquisite regulation of PI3K/AKT/mTORC1 signaling is essential for homeostatic control of cell growth, proliferation, and survival. Aberrant activation of this signaling network is an early driver of many sporadic human cancers. Paradoxically, sustained hyperactivation of the PI3K/AKT/mTORC1 pathway in nontransformed cells results in cellular senescence, which is a tumor-suppressive mechanism that must be overcome to promote malignant transformation. While oncogene-induced senescence (OIS) driven by excessive RAS/ERK signaling has been well studied, little is known about the mechanisms underpinning the AKT-induced senescence (AIS) response. Here, we utilize a combination of transcriptome and metabolic profiling to identify key signatures required to maintain AIS. We also employ a whole protein-coding genome RNAi screen for AIS escape, validating a subset of novel mediators and demonstrating their preferential specificity for AIS as compared with OIS. As proof of concept of the potential to exploit the AIS network, we show that neurofibromin 1 (NF1) is upregulated during AIS and its ability to suppress RAS/ERK signaling facilitates AIS maintenance. Furthermore, depletion of NF1 enhances transformation of p53-mutant epithelial cells expressing activated AKT, while its overexpression blocks transformation by inducing a senescent-like phenotype. Together, our findings reveal novel mechanistic insights into the control of AIS and identify putative senescence regulators that can potentially be targeted, with implications for new therapeutic options to treat PI3K/AKT/mTORC1-driven cancers.

Inhibition of RNA polymerase I transcription initiation by CX-5461 activates non-canonical ATM/ATR signaling

RNA polymerase I (Pol I)-mediated transcription of the ribosomal RNA genes (rDNA) is confined to the nucleolus and is a rate-limiting step for cell growth and proliferation. Inhibition of Pol I by CX-5461 can selectively induce p53-mediated apoptosis of tumour cells in vivo. Currently, CX-5461 is in clinical trial for patients with advanced haematological malignancies (Peter Mac, Melbourne). Here we demonstrate that CX-5461 also induces p53-independent cell cycle checkpoints mediated by ATM/ATR signaling in the absence of DNA damage. Further, our data demonstrate that the combination of drugs targeting ATM/ATR signaling and CX-5461 leads to enhanced therapeutic benefit in treating p53-null tumours in vivo, which are normally refractory to each drug alone. Mechanistically, we show that CX-5461 induces an unusual chromatin structure in which transcriptionally competent relaxed rDNA repeats are devoid of transcribing Pol I leading to activation of ATM signaling within the nucleoli. Thus, we propose that acute inhibition of Pol transcription initiation by CX-5461 induces a novel nucleolar stress response that can be targeted to improve therapeutic efficacy.

MicroRNA-377 suppresses initiation and progression of esophageal cancer by inhibiting CD133 and VEGF

Esophageal cancer is one of the most lethal cancers worldwide with poor survival and limited therapeutic options. The discovery of microRNAs created a new milestone in cancer research. miR-377 is located in chromosome region 14q32, which is frequently deleted in esophageal squamous cell carcinoma (ESCC), but the biological functions, clinical significance and therapeutic implication of miR-377 in ESCC are largely unknown. In this study, we found that miR-377 expression was significantly downregulated in tumor tissue and serum of patients with ESCC. Both tumor tissue and serum miR-377 expression levels were positively correlated with patient survival. Higher serum miR-377 expression was inversely associated with pathologic tumor stage, distant metastasis, residual tumor status and chemoradiotherapy resistance. The roles of miR-377 in suppressing tumor initiation and progression, and the underlying molecular mechanisms were investigated. Results of in vitro and in vivo experiments showed that miR-377 overexpression inhibited the initiation, growth and angiogenesis of ESCC tumors as well as metastatic colonization of ESCC cells, whereas silencing of miR-377 had opposite effects. Mechanistically, miR-377 regulated CD133 and VEGF by directly binding to their 3' untranslated region. Moreover, systemic delivery of formulated miR-377 mimic not only suppressed tumor growth in nude mice but also blocked tumor angiogenesis and metastasis of ESCC cells to the lungs without overt toxicity to mice. Collectively, our study established that miR-377 plays a functional and significant role in suppressing tumor initiation and progression, and may represent a promising non-invasive diagnostic and prognostic biomarker and therapeutic strategy for patients with ESCC.

Transcatheter aortic valve implantation: initial experience in Hong Kong

INTRODUCTION

Aortic stenosis is one of the most common valvular heart diseases in the ageing population. Patients with symptomatic severe aortic stenosis are at high risk of sudden death. Surgical aortic-valve replacement is the gold standard of treatment but many patients do not receive surgery because of advanced age or co-morbidities. Recently, transcatheter aortic valve implantation has been developed as an option for these patients. This study aimed to assess efficacy and safety of this procedure in the Hong Kong Chinese population.

METHODS

Data for baseline patient characteristics, procedure parameters, and clinical outcomes up to 1-year post-implantation in a regional hospital in Hong Kong were collected and analysed.

RESULTS

A total of 56 patients with severe aortic stenosis underwent the procedure from December 2010 to September 2015. Their mean (± standard deviation) age was 81.9 ± 4.8 years; 64.3% of them were male. Their mean logistic EuroSCORE was 22.6% ± 13.4%. After implantation, the mean aortic valve area improved from 0.70 cm² ± 0.19 cm² to 1.94 cm² ± 0.37 cm². Of the patients, 92% were improved by at least one New York Heart Association functional class. Stroke and major vascular complications occurred in one (1.8%) and five (8.9%) patients, respectively. A permanent pacemaker was implanted in seven (12.5%) patients. Both hospital and 30-day mortalities were 1.8%. The 1-year all-cause and cardiovascular mortality rates were 12.5% and 7.1%, respectively.

CONCLUSIONS

Transcatheter aortic valve implantation has been developed as an alternative treatment for patients with symptomatic severe aortic stenosis who are deemed inoperable or high risk for surgery. Our results are very promising and comparable with those of major clinical trials.

Abstract A24: A genome-wide RNAi screen identifies synthetic lethality of CX-5461 with homologous recombination repair deficiency in ovarian cancer

Cancer is characterized by deregulated cell growth and proliferation, both of which are associated with hyperactivation of ribosome biogenesis. Inhibition of ribosome biogenesis using CX-5461, a specific inhibitor of RNA polymerase I-dependent transcription, has shown therapeutic efficacy in a MYC driven B-cell lymphoma mouse model, which is enhanced when used in combination with the mTORC1 inhibitor Everolimus. However, the therapeutic potential of CX-5461 in solid cancers is yet to be determined.

Our preliminary data utilizing a panel of 36 ovarian cancer (OVCA) cell lines suggest that acute CX-5461 treatment results in cell cycle arrest and does not induce apoptosis. We hypothesize that the identification of genes that can be targeted to cooperate with CX-5461 will define novel drug combinations for the improved treatment of OVCA. Therefore, we performed a genome-wide RNAi screen to identify synthetic lethal genes with CX-5461 in the high-grade serous ovarian cancer (HGSOC) cell line OVCAR4. Pathway enrichment analysis of the candidate hits showed significant enrichment in the homologous recombination DNA repair (HR) pathway. Synergy with CX-5461 was validated in multiple HGSOC cell lines by both genetic and pharmacological inhibition of HR pathway components. We are currently investigating the mechanism of this synergy and will further assess efficacy in vivo.

As HR deficiency is observed in 20% of OVCA patients, we suggest that future application of our studies will lead to new therapeutic options to improve the survival of this cohort of patients.

Citation Format: Shunfei Yan, Keefe T. Chan, Kaylene J. Simpson, Elaine Sanij, Karen E. Sheppard, Katherine M. Hannan, Ross D. Hannan, Richard B. Pearson. A genome-wide RNAi screen identifies synthetic lethality of CX-5461 with homologous recombination repair deficiency in ovarian cancer [abstract]. In: Proceedings of the AACR Special Conference on DNA Repair: Tumor Development and Therapeutic Response; 2016 Nov 2-5; Montreal, QC, Canada. Philadelphia (PA): AACR; Mol Cancer Res 2017;15(4_Suppl):Abstract nr A24.

Combining High-Content Imaging and Phenotypic Classification Analysis of Senescence-Associated Beta-Galactosidase Staining to Identify Regulators of Oncogene-Induced Senescence

Hyperactivation of the PI3K/AKT/mTORC1 signaling pathway is a hallmark of the majority of sporadic human cancers. Paradoxically, chronic activation of this pathway in nontransformed cells promotes senescence, which acts as a significant barrier to malignant progression. Understanding how this oncogene-induced senescence is maintained in nontransformed cells and conversely how it is subverted in cancer cells will provide insight into cancer development and potentially identify novel therapeutic targets. High-throughput screening provides a powerful platform for target discovery. Here, we describe an approach to use RNAi transfection of a pre-established AKT-induced senescent cell population and subsequent high-content imaging to screen for senescence regulators. We have incorporated multiparametric readouts, including cell number, proliferation, and senescence-associated beta-galactosidase (SA-βGal) staining. Using machine learning and automated image analysis, we also describe methods to classify distinct phenotypes of cells with SA-βGal staining. These methods can be readily adaptable to high-throughput functional screens interrogating the mechanisms that maintain and prevent senescence in various contexts.

IL2 Inducible T-cell Kinase, a Novel Therapeutic Target in Melanoma

PURPOSE

IL2 inducible T-cell kinase (ITK) promoter CpG sites are hypomethylated in melanomas compared with nevi. The expression of ITK in melanomas, however, has not been established and requires elucidation.

EXPERIMENTAL DESIGN

An ITK-specific monoclonal antibody was used to probe sections from deidentified, formalin-fixed paraffin-embedded tumor blocks or cell line arrays and ITK was visualized by IHC. Levels of ITK protein differed among melanoma cell lines and representative lines were transduced with four different lentiviral constructs that each contained an shRNA designed to knockdown ITK mRNA levels. The effects of the selective ITK inhibitor BI 10N on cell lines and mouse models were also determined.

RESULTS

ITK protein expression increased with nevus to metastatic melanoma progression. In melanoma cell lines, genetic or pharmacologic inhibition of ITK decreased proliferation and migration and increased the percentage of cells in the G0-G1 phase. Treatment of melanoma-bearing mice with BI 10N reduced growth of ITK-expressing xenografts or established autochthonous (Tyr-Cre/Pten(null)/Braf(V600E)) melanomas.

CONCLUSIONS

We conclude that ITK, formerly considered an immune cell-specific protein, is aberrantly expressed in melanoma and promotes tumor development and progression. Our finding that ITK is aberrantly expressed in most metastatic melanomas suggests that inhibitors of ITK may be efficacious for melanoma treatment. The efficacy of a small-molecule ITK inhibitor in the Tyr-Cre/Pten(null)/Braf(V600E) mouse melanoma model supports this possibility.

β2-adrenoceptor signaling regulates invadopodia formation to enhance tumor cell invasion

Introduction

For efficient metastatic dissemination, tumor cells form invadopodia to degrade and move through three-dimensional extracellular matrix. However, little is known about the conditions that favor invadopodia formation. Here, we investigated the effect of β-adrenoceptor signaling - which allows cells to respond to stress neurotransmitters - on the formation of invadopodia and examined the effect on tumor cell invasion.

Methods

To characterize the molecular and cellular mechanisms of β-adrenergic signaling on the invasive properties of breast cancer cells, we used functional cellular assays to quantify invadopodia formation and to evaluate cell invasion in two-dimensional and three-dimensional environments. The functional significance of β-adrenergic regulation of invadopodia was investigated in an orthotopic mouse model of spontaneous breast cancer metastasis.

Results

β-adrenoceptor activation increased the frequency of invadopodia-positive tumor cells and the number of invadopodia per cell. The effects were selectively mediated by the β₂-adrenoceptor subtype, which signaled through the canonical Src pathway to regulate invadopodia formation. Increased invadopodia occurred at the expense of focal adhesion formation, resulting in a switch to increased tumor cell invasion through three-dimensional extracellular matrix. β₂-adrenoceptor signaling increased invasion of tumor cells from explanted primary tumors through surrounding extracellular matrix, suggesting a possible mechanism for the observed increased spontaneous tumor cell dissemination in vivo. Selective antagonism of β₂-adrenoceptors blocked invadopodia formation, suggesting a pharmacological strategy to prevent tumor cell dissemination.

Conclusion

These findings provide insight into conditions that control tumor cell invasion by identifying signaling through β₂-adrenoceptors as a regulator of invadopodia formation. These findings suggest novel pharmacological strategies for intervention, by using β-blockers to target β₂-adrenoceptors to limit tumor cell dissemination and metastasis.

LKB1 loss in melanoma disrupts directional migration toward extracellular matrix cues

The LKB1 kinase regulates directional migration in response to extracellular matrix gradients and may inhibit invasive motility by sensing inhibitory matrix cues.

Somatic inactivation of the serine/threonine kinase gene STK11/LKB1/PAR-4 occurs in a variety of cancers, including ∼10% of melanoma. However, how the loss of LKB1 activity facilitates melanoma invasion and metastasis remains poorly understood. In LKB1-null cells derived from an autochthonous murine model of melanoma with activated Kras and Lkb1 loss and matched reconstituted controls, we have investigated the mechanism by which LKB1 loss increases melanoma invasive motility. Using a microfluidic gradient chamber system and time-lapse microscopy, in this paper, we uncover a new function for LKB1 as a directional migration sensor of gradients of extracellular matrix (haptotaxis) but not soluble growth factor cues (chemotaxis). Systematic perturbation of known LKB1 effectors demonstrated that this response does not require canonical adenosine monophosphate–activated protein kinase (AMPK) activity but instead requires the activity of the AMPK-related microtubule affinity-regulating kinase (MARK)/PAR-1 family kinases. Inhibition of the LKB1–MARK pathway facilitated invasive motility, suggesting that loss of the ability to sense inhibitory matrix cues may promote melanoma invasion.

Predicting 1-year risk for relapse in patients who have discontinued or continued quetiapine after remission from first-episode psychosis

OBJECTIVE

Relapse is common among patients with psychotic disorders. Identification of relapse predictors is important for decision regarding maintenance medication. Naturalistic studies often identify medication non-adherence as a dominant predictor. There are relatively few studies for predictors where adherence is already known. It is this situation i.e., discontinuation of medication that predictors will be most useful. We identify predictors for relapse in situations of (i) discontinuation and (ii) continuation of maintenance medication.

METHOD

Analysis of relapse predictors is based on a randomized controlled study (n=178) comparing relapse rates between patients who discontinued or continued medication for at least 1 year following first-episode psychosis. Demographic, clinical and neurocognitive variables were assessed at baseline as predictors of relapse within 1 year.

RESULTS

Risk of relapse was 79% in the discontinuation group and 41% in the maintenance group. Predictors in the discontinuation group were diagnosis of schizophrenia, poorer semantic fluency performance, and higher blink rate. Predictors in the continuation group were disinhibition soft signs and more general psychopathology symptoms.

CONCLUSION

Different predictors of relapse were identified for first episode psychosis patients who discontinued and continued maintenance medication. Neurocognitive dysfunctions are important predictors for both groups. While signs of frontal dysfunction and dopamine hyperactivity predict relapse in the discontinuation group, sign of cognitive disinhibition predicts relapse in the continuation group.

Intravital imaging of a spheroid-based orthotopic model of melanoma in the mouse ear skin

Multiphoton microscopy is a powerful tool that enables the visualization of fluorescently tagged tumor cells and their stromal interactions within tissues in vivo. We have developed an orthotopic model of implanting multicellular melanoma tumor spheroids into the dermis of the mouse ear skin without the requirement for invasive surgery. Here, we demonstrate the utility of this approach to observe the primary tumor, single cell actin dynamics, and tumor-associated vasculature. These methods can be broadly applied to investigate an array of biological questions regarding tumor cell behavior in vivo.

Abstract C14: Loss of haptotaxis facilitates invasion in LKB1-deficient melanoma

Germline mutations in the serine/threonine kinase STK11/LKB1 are associated with Peutz-Jehgers Syndrome, which is characterized by hyperpigmentation of the oral mucosa. Inactivating somatic mutations occur in approximately 10-20% of melanomas; however, how the loss of LKB1 facilitates melanoma invasion remains poorly understood. Using cell lines derived from simultaneous activation of KRas and inactivation of LKB1 in melanocytes, we have investigated melanoma migration upon reconstitution with LKB1. Reexpression of LKB1 diminishes migration during wound healing, spheroid outgrowth into 3D collagen, and overall single cell speed in random motility assays. Furthermore, the formation of invadopodia is independent of LKB1 status in both human and mouse melanomas. Interestingly, using microfluidic devices we have found that loss of LKB1 abrogates the ability of cells to respond to gradients of extracellular matrix (haptotaxis) but does not impair their ability to chemotax to EGF. We have also recently developed a model of orthotopic implantation of multicellular tumor spheroids into the dermis of the mouse ear skin and have validated this approach by recapitulating the finding that LKB1 limits tumorigenesis. We are using this model to image local invasion in vivo by multiphoton microscopy and are currently examining the intriguing hypothesis that loss of extracellular matrix sensing is one aspect that contributes to metastatic migration.

Citation Format: Keefe T. Chan, Sreeja B. Asokan, Tao Bo, Matthew E. Berginski, Wenjin Liu, Shelly D. Cochran, Norman E. Sharpless, James E. Bear. Loss of haptotaxis facilitates invasion in LKB1-deficient melanoma. [abstract]. In: Proceedings of the AACR Special Conference on Tumor Invasion and Metastasis; Jan 20-23, 2013; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2013;73(3 Suppl):Abstract nr C14.

A prospective study of bacterial flora in nasal cavity of patients with persistent allergic rhinitis

It remains unanswered whether persistent allergic inflammation in nasal mucosa alters bacterial colonization and infection. The aim of this study was to investigate the bacterial flora in the nasal cavity of patients with persistent allergic rhinitis (PAR) and to correlate the bacteriological findings with presence of nasal symptoms, nasal eosinophil and neutrophil counts. A total of 255 subjects, aged between 6 - 74 years (mean 33.9 years) was randomly selected from a population-based rhinitis survey study in Singapore. All subjects went through a thorough medical history and nasal examinations. Serum specific IgE to a panel of common house dust mites, nasal cytological and microbiological examinations were performed. PAR was diagnosed in 107 patients and none of them had received previous regular therapy. There is a significant relationship between PAR and eosinophil grades, but not with neutrophil count. No statistically significant difference was found in quantitative and qualitative bacterial flora in nasal cavity between PAR patients and subjects with non-rhinitis or with non-allergic rhinitis. There is a significant inverse correlation between ongoing rhinorrhoea and quantitative bacterial load, and between signs of nasal mucosa (pale and edema) and the presence and type of bacterial pathogens. In conclusion, our study demonstrates that patients with untreated (or using PRN medicine) PAR do not result in a significant change in bacterial flora in their nasal cavity.

LKB1/STK11 inactivation leads to expansion of a prometastatic tumor subpopulation in melanoma

Germline mutations in LKB1 (STK11) are associated with the Peutz-Jeghers syndrome (PJS), which includes aberrant mucocutaneous pigmentation, and somatic LKB1 mutations occur in 10% of cutaneous melanoma. By somatically inactivating Lkb1 with K-Ras activation (±p53 loss) in murine melanocytes, we observed variably pigmented and highly metastatic melanoma with 100% penetrance. LKB1 deficiency resulted in increased phosphorylation of the SRC family kinase (SFK) YES, increased expression of WNT target genes, and expansion of a CD24(+) cell population, which showed increased metastatic behavior in vitro and in vivo relative to isogenic CD24(-) cells. These results suggest that LKB1 inactivation in the context of RAS activation facilitates metastasis by inducing an SFK-dependent expansion of a prometastatic, CD24(+) tumor subpopulation.

Unraveling the enigma: progress towards understanding the coronin family of actin regulators

Coronins are a conserved family of actin cytoskeleton regulators that promote cell motility and modulate other actin-dependent processes. Although these proteins have been known for 20 years, substantial progress has been made in the past 5 years towards their understanding. In this review, we examine this progress, place it into the context of what was already known, and pose several questions that remain to be addressed. In particular, we cover the emerging consensus about the role of Type I coronins in coordinating the function of Arp2/3 complex and ADF/cofilin proteins. This coordination plays an important role in leading-edge actin dynamics and overall cell motility. Finally, we discuss the roles played by the more exotic coronins of the Type II and III classes in cellular processes away from the leading edge.

Maintenance treatment with quetiapine versus discontinuation after one year of treatment in patients with remitted first episode psychosis: randomised controlled trial

OBJECTIVE

To study rates of relapse in remitted patients with first episode psychosis who either continued or discontinued antipsychotic drugs after at least one year of maintenance treatment.

DESIGN

12 month randomised, double blind, placebo controlled trial.

SETTING

Early psychosis outpatient clinics in Hong Kong.

PARTICIPANTS

178 patients with first episode psychosis who had received at least one year of antipsychotic drug treatment between September 2003 and July 2006 and had no positive symptoms of psychosis.

INTERVENTIONS

Patients received either maintenance treatment with quetiapine (400 mg/day) or placebo and were followed up for the next 12 months or until a relapse occurred.

MAIN OUTCOME MEASURE

Relapse assessed monthly and defined as re-emergence of psychotic symptoms (delusions, conceptual disorganisation, hallucinations, suspiciousness, and unusual thought content) according to predefined thresholds.

RESULTS

178 patients were randomised (89 to quetiapine and 89 to placebo). The Kaplan-Meier estimate of the risk of relapse at 12 months was 41% (95% confidence interval 29% to 53%) for the quetiapine group and 79% (68% to 90%) for the placebo group (P<0.001). Although quetiapine was generally well tolerated, the rate of discontinuation due to adverse or serious adverse events was greater in the quetiapine group (18%; 16/89) than in the placebo group (8%; 7/89) (relative risk 2.29, 95% confidence interval 0.99 to 5.28; chi(2)=3.20, df=1; P=0.07).

CONCLUSION

In a group of asymptomatic patients with first episode psychosis and at least one year of previous antipsychotic drug treatment, maintenance treatment with quetiapine compared with placebo resulted in a substantially lower rate of relapse during the following year. Trial registration Clinical trials NCT00334035.

Regulation of adhesion dynamics by calpain-mediated proteolysis of focal adhesion kinase (FAK)

The coordinated and dynamic regulation of adhesions is required for cell migration. We demonstrated previously that limited proteolysis of talin1 by the calcium-dependent protease calpain 2 plays a critical role in adhesion disassembly in fibroblasts (Franco, S. J., Rodgers, M. A., Perrin, B. J., Han, J., Bennin, D. A., Critchley, D. R., and Huttenlocher, A. (2004) Nat. Cell Biol. 6, 977-983). However, little is known about the contribution of other calpain substrates to the regulation of adhesion dynamics. We now provide evidence that calpain 2-mediated proteolysis of focal adhesion kinase (FAK) regulates adhesion dynamics in motile cells. We mapped the preferred calpain cleavage site between the two C-terminal proline-rich regions after Ser-745, resulting in a C-terminal fragment similar in size to the FAK-related non-kinase (FRNK). We generated mutant FAK with a point mutation (V744G) that renders FAK resistant to calpain proteolysis but retains other biochemical properties of FAK. Using time-lapse microscopy, we show that the dynamics of green fluorescent protein-talin1 are impaired in FAK-deficient cells. Expression of wild-type but not calpain-resistant FAK rescues talin dynamics in FAK-deficient cells. Taken together, our findings suggest a novel role for calpain proteolysis of FAK in regulating adhesion dynamics in motile cells.

FAK alters invadopodia and focal adhesion composition and dynamics to regulate breast cancer invasion

Focal adhesion kinase (FAK) is important for breast cancer progression and invasion and is necessary for the dynamic turnover of focal adhesions. However, it has not been determined whether FAK also regulates the dynamics of invasive adhesions formed in cancer cells known as invadopodia. In this study, we report that endogenous FAK functions upstream of cellular Src (c-Src) as a negative regulator of invadopodia formation and dynamics in breast cancer cells. We show that depletion of FAK induces the formation of active invadopodia but impairs invasive cell migration. FAK-deficient MTLn3 breast cancer cells display enhanced assembly and dynamics of invadopodia that are rescued by expression of wild-type FAK but not by FAK that cannot be phosphorylated at tyrosine 397. Moreover, our findings demonstrate that FAK depletion switches phosphotyrosine-containing proteins from focal adhesions to invadopodia through the temporal and spatial regulation of c-Src activity. Collectively, our findings provide novel insight into the interplay between FAK and Src to promote invasion.

Mouse studies of SARS coronavirus-specific immune responses to recombinant replication-defective adenovirus expressing SARS coronavirus N protein

1. A recombinant adenovirus encoding SARS coronavirus(SARS-CoV) nucleocapsid protein (rAd-N) was constructed. 2. The ability of the rAd-N to induce anti-SARS-CoV N antibody production and cellular immune responses was evaluated in an HLA-A2.1/Kb transgenic mouse model.

Investigation of immunogenic T-cell epitopes in SARS virus nucleocapsid protein and their role in the prevention and treatment of SARS infection

1. A novel HLA-A2.1-specific SARS coronavirus (SARS-CoV) nucleocapsid (N) protein epitope (N220-N228 LALLLLDRL) able to activate cytotoxic T cells in vitro has been identified. 2. When used with a single-chain-trimer system, the SARS-CoV N protein epitope (N220-N228 LALLLLDRL) can stimulate a cytotoxic T-cell response against N-protein expressing cells in the HLA-A2.1K(b) transgenic mouse model.

Calpain 2 and PTP1B function in a novel pathway with Src to regulate invadopodia dynamics and breast cancer cell invasion

Invasive cancer cells form dynamic adhesive structures associated with matrix degradation called invadopodia. Calpain 2 is a calcium-dependent intracellular protease that regulates adhesion turnover and disassembly through the targeting of specific substrates such as talin. Here, we describe a novel function for calpain 2 in the formation of invadopodia and in the invasive abilities of breast cancer cells through the modulation of endogenous c-Src activity. Calpain-deficient breast cancer cells show impaired invadopodia formation that is rescued by expression of a truncated fragment of protein tyrosine phosphatase 1B (PTP1B) corresponding to the calpain proteolytic fragment, which indicates that calpain modulates invadopodia through PTP1B. Moreover, PTP1B activity is required for efficient invadopodia formation and breast cancer invasion, which suggests that PTP1B may modulate breast cancer progression through its effects on invadopodia. Collectively, our experiments implicate a novel signaling pathway involving calpain 2, PTP1B, and Src in the regulation of invadopodia and breast cancer invasion.

Type Igamma PIP kinase is a novel uropod component that regulates rear retraction during neutrophil chemotaxis

Cell polarization is necessary for directed migration and leukocyte recruitment to inflamed tissues. Recent progress has been made in defining the molecular mechanisms that regulate chemoattractant-induced cell polarity during chemotaxis, including the contribution of phosphoinositide 3-kinase (PI3K)-dependent phosphatidylinositol (3,4,5)-trisphosphate [PtdIns(3,4,5)P(3)] synthesis at the leading edge. However, less is known about the molecular composition of the cell rear and how the uropod functions during cell motility. Here, we demonstrate that phosphatidylinositol phosphate kinase type Igamma (PIPKIgamma661), which generates PtdIns(4,5)P(2), is enriched in the uropod during chemotaxis of primary neutrophils and differentiated HL-60 cells (dHL-60). Using time-lapse microscopy, we show that enrichment of PIPKIgamma661 at the cell rear occurs early upon chemoattractant stimulation and is persistent during chemotaxis. Accordingly, we were able to detect enrichment of PtdIns(4,5)P(2) at the uropod during chemotaxis. Overexpression of kinase-dead PIPKIgamma661 compromised uropod formation and rear retraction similar to inhibition of ROCK signaling, suggesting that PtdIns(4,5)P(2) synthesis is important to elicit the backness response during chemotaxis. Together, our findings identify a previously unknown function for PIPKIgamma661 as a novel component of the backness signal that regulates rear retraction during chemotaxis.

Integrins in Cell Migration

Integrins are cell-surface adhesion receptors that play a central role in regulating cell migration by mediating interactions between the extracellular matrix and the actin cytoskeleton. Substantial progress has been made in understanding the mechanisms by which the formation and breakdown of adhesions are regulated. Here we describe general methods used to study integrin-mediated cell migration. Furthermore, we outline detailed procedures to examine focal adhesion assembly and disassembly using time-lapse fluorescent microscopy. Finally, we provide methods for the analysis of podosomes, which are highly dynamic adhesive structures that form in immune cells and invasive cancer cells.

Treatment of long, diffuse in-stent restenosis with sirolimus-eluting stents

Treatment of long, diffuse in-stent restenosis remains a therapeutic challenge. We report the successful use of multiple sirolimus-eluting stents (three 33-mm long stents) in a long, diffuse in-stent restenotic lesion. No major adverse cardiovascular events, including acute/subacute/delayed stent thrombosis, were noted at ten months. Angiography at six months showed widely patent stents with 19% restenosis only at the worst segment.

The use of a distal occlusion balloon protection device in acute coronary syndrome

We report our early experience in using the PercuSurge GuardWire Plus system as a distal protection device in patients with acute coronary syndrome and acute myocardial infarction. Forty-three patients received percutaneous coronary intervention with the GuardWire Plus system. Thirteen had unstable angina, five had non-Q myocardial infarction and 25 had ST segment elevation myocardial infarction. Forty-one target lesions were in native coronary vessels and two were in saphenous vein grafts. Total occlusion occurred in 18 patients. The mean occlusion time by the distal protective balloon was 262.8 +/- 114.1 s. Preoperatively, TIMI 0 flow was present in 18, TIMI II flow in two and TIMI III flow in 23 patients. Post-operatively, TIMI II and TIMI III flow were established in two and 41 patients, respectively. All procedures were successful and the GuardWire Plus system was successfully deployed in all but two patients. There was no procedure-related major adverse clinical event. There was no major adverse clinical event at 30 days. There was no device-related complication. We believe that the GuardWire Plus system is safe and feasible in patients with acute coronary syndrome and acute myocardial infarction.

A humanized monoclonal antibody constructed from intronless expression vectors targets human hepatocellular carcinoma cells

An anti-human hepatocellular carcinoma (HCC) monoclonal antibody, hHP-1, was genetically humanized from a murine monoclonal antibody. In this study, a concept of positional template approach was applied to design the amino acid sequence of hHP-1's variable region, and synthetic DNA fragments for protein expression were produced through overlapping PCR from single strand oligonucleotides. Synthetic DNA fragments and human antibody constant region cDNA were used to construct two CMV promotor-based expression vectors for the antibody light and heavy chains, in which the variable region was connected directly to the constant region without an intron sequence. Completely assembled humanized antibody was successfully expressed in mammalian cells as IgG1 kappa molecules and purified using protein A affinity column. The immunogenicity of the hHP1 was estimated by the amino acid sequence and determined through a HAMA (human anti-murine antibody) serum reaction assay. Results indicated that the immunogenicity of hHP-1 was significantly reduced. In vitro binding activity assay showed that the hHP-1 had retained its binding function to a human HCC SMMC-7721 cell-line, without cross binding to other human normal tissues. Immunofluorescence staining showed that hHP-1 had a strong binding activity to SMMC cells. A competitive binding assay showed that the relative binding activity of hHP-1 was approximately 25% binding activity of the original murine antibody. Our results indicate that a humanized antibody could be produced using intronless vectors and expressed as a complete IgG1 kappa antibody. Hence we believe that hHP-1 could be a potential candidate for HCC treatment.

Lumbosacral plexopathy in gunshot wounds and motor vehicle accidents: comparison of electrophysiologic findings

OBJECTIVE

To characterize the differences between injuries to the lumbosacral (LS) plexus caused by gunshot wounds (GSW) and motor vehicle crashes (MVC) with regard to the location and extent of involvement.

DESIGN

A retrospective review of electrophysiologic data from an electromyography laboratory of a county hospital. Nineteen patients with GSW and ten patients with MVC diagnosed by electromyography with an LS plexopathy were included in the study. Injuries were categorized by the number of anatomic quadrants of the LS plexus: upper anterior, upper posterior, lower anterior, and lower posterior. Comparison of upper vs. lower portions and bilaterality of LS plexus involvement was also made. Statistical analyses were performed with two-tailed Fisher's exact and general association tests.

RESULTS

Lower portions of the plexus were involved more frequently in patients with MVC compared those observed in patients with GSW. Upper portions of the LS plexus were more involved compared with the lower portions in patients with GSW injuries. More sections of the plexus were involved in patients with MVC compared with those in patients with GSW.

CONCLUSIONS

Compared with patients with MVC, patients with GSW had a greater chance of involvement of the upper portion of the plexus. The reverse was true for the lower portion. Hopefully this information will aid the electromyographer and rehabilitation team in the diagnosis and treatment of traumatic plexopathies caused by different etiologies.

Differential expression of a stress-modulating gene, BRE, in the adrenal gland, in adrenal neoplasia, and in abnormal adrenal tissues

Genes that modulate the action of hormones and cytokines play a critical role in stress response, survival, and in growth and differentiation of cells. Many of these biological response modifiers are responsible for various pathological conditions, including inflammation, infection, cachexia, aging, genetic disorders, and cancer. We have previously identified a new gene, BRE, that is responsive to DNA damage and retinoic acid. Using multiple-tissue dot-blotting and Northern blotting, BRE was recently found to be strongly expressed in adrenal cortex and medulla, in testis, and in pancreas, whereas low expression was found in the thyroid, thymus, small intestine and stomach. In situ hybridization and immunohistochemical staining indicated that BRE was strongly expressed in the zona glomerulosa of the adrenal cortex, which synthesizes and secretes the mineralocorticoid hormones. It is also highly expressed in the glial and neuronal cells of the brain and in the round spermatids, Sertoli cells, and Leydig cells of the testis, all of which are associated with steroid hormones and/or TNF synthesis. However, BRE expression was downregulated in human adrenal adenoma and pheochromocytoma, whereas its expression was enhanced in abnormal adrenal tissues of rats chronically treated with nitrate or nitrite. These data, taken together, indicate that the expression of BRE is apparently associated with steroids and/or TNF production and the regulation of endocrine functions. BRE may play an important role in the endocrine and immune system, such as the cytokine-endocrine interaction of the adrenal gland.

Sacroiliac joint pain referral zones

OBJECTIVE

To determine the patterns of pain referral from the sacroiliac joint.

STUDY DESIGN

Retrospective.

PARTICIPANTS/METHODS

Fifty consecutive patients who satisfied clinical criteria and demonstrated a positive diagnostic response to a fluoroscopically guided sacroiliac joint injection were included. Each patient's preinjection pain description was used to determine areas of pain referral, and 18 potential pain-referral zones were established.

OUTCOME MEASURES

Observed areas of pain referral.

RESULTS

Eighteen men (36.0%) and 32 women (64.0%) were included with a mean age of 42.5 years (range, 20 to 75 yrs) and a mean symptom duration of 18.2 months (range, 1 to 72 mo). Forty-seven patients (94.0%) described buttock pain, and 36 patients (72.0%) described lower lumbar pain. Groin pain was described in 7 patients (14.0%). Twenty-five patients (50.0%) described associated lower-extremity pain. Fourteen patients (28.0%) described leg pain distal to the knee, and 6 patients (14.0%) reported foot pain. Eighteen patterns of pain referral were observed. A statistically significant relationship was identified between pain location and age, with younger patients more likely to describe pain distal to the knee.

CONCLUSIONS

Pain referral from the sacroiliac joint does not appear to be limited to the lumbar region and buttock. The variable patterns of pain referral observed may arise for several reasons, including the joint's complex innervation, sclerotomal pain referral, irritation of adjacent structures, and varying locations of injury with the sacroiliac joint.

Telomerase activity in thyroid malignancy

Telomerase activity seems to play a role in the development and pathogenesis of thyroid carcinoma. Its incidence of expression and its application as a tumor marker remain to be elucidated. Thyroid tissues obtained during thyroidectomy from 1996-1998 were rapidly frozen and stored at -80 degrees C until processed. Telomerase activity was determined using telomeric repeat amplification protocol (TRAP). Histology of the tissue examined (67 benign and 59 malignant) was reviewed. Telomerase activity was detected in 15 of 52 papillary carcinomas (29%); 1 of 1 thyroid lymphoma (100%); 1 of 2 anaplastic carcinomas (50%); and 2 of 16 lymphocytic thyroiditis specimens (13%). Telomerase activity was not detectable in 35 normal thyroid, 9 follicular adenoma, 7 nodular hyperplasia, 2 follicular carcinoma, and 2 medullary carcinoma. Lymphocytic thyroiditis was detected in 8 of 37 (22%) apparently normal thyroid tissues adjacent to papillary thyroid carcinoma and telomerase activity was present in 2 of these 8 specimens (25%). In conclusion, telomerase does not appear to be frequently activated in papillary thyroid carcinoma. The association of lymphocytic thyroiditis with papillary thyroid carcinoma may limit its clinical usefulness as a tumor marker.

Modulation of Ca2+-dependent anion secretion by protein kinase C in normal and cystic fibrosis pancreatic duct cells

The study investigated the role of protein kinase C (PKC) in the modulation of agonist-induced Ca2+-dependent anion secretion by pancreatic duct cells. The short-circuit current (ISC) technique was used to examine the effect of PKC activation and inhibition on subsequent ATP, angiotensin II and ionomycin-activated anion secretion by normal (CAPAN-1) and cystic fibrosis (CFPAC-1) pancreatic duct cells. The ISC responses induced by the Ca2+-mobilizing agents, which had been previously shown to be attributed to anion secretion, were enhanced in both CAPAN-1 and CFPAC-1 cells by PKC inhibitors, staurosporine, calphostin C or chelerythrine. On the contrary, a PKC activator, phorbol 12-myristate 13-acetate (PMA), was found to suppress the agonist-induced ISC in CFPAC-1 cells and the ionomycin-induced ISC in CAPAN-1 cells. An inactive form of PMA, 4alphad-phorbol 12, 13-didecanote (4alphaD), was found to exert insignificant effect on the agonist-induced ISC, indicating a specific effect of PMA. Our data suggest a role of PKC in modulating agonist-induced Ca2+-dependent anion secretion by pancreatic duct cells. Therapeutic strategy to augment Ca2+-activated anion secretion by cystic fibrosis pancreatic duct cells may be achieved by inhibition or down-regulation of PKC.

Identification of antinodes and zero-surface-strain contours of flexural vibration with time-averaged speckle pattern shearing interferometry

A new time-averaged frame subtraction technique is introduced for vibration analysis by digital speckle shearing interferometry. The technique permits the enhancement of fringes by subtracting two Bessel fringe patterns at different forcing levels. Compared with the phase-shift method, this method is more efficient and easier to implement for qualitative vibration measurement, providing a means for fast inspection of plate vibration behavior. It is also capable of tracing contours of zero strain and locating antinodes on vibrating plates.

[The clinical efficacy of and tolerance for lariam (mefloquine) in tropical malaria in the south of the Socialist Republic of Vietnam]

The study was performed in the area of distribution of tropical malaria resistant to 4-aminoquinolines (Vietnam) on 30 patients receiving lariam (mefloquine). The results were compared to the standard therapy with quinine and fansidar. They indicate a high efficacy of and a good tolerance to the drug tested. The use of lariam leads to a more rapid (as compared to the standard treatment) elimination of parasitemia and complete eradication of the disease relapses. The findings make it possible to recommend lariam for the prevention and treatment of tropical malaria.

Giant cell tumor of the distal end of the radius treated by the resection and free vascularized iliac crest graft

Juxtaarticular giant cell tumor involving the distal radius presents a special problem of reconstruction after tumor excision. A tailored block of vascularized iliac crest graft with its feeding artery (i.e., the deep circumflex iliac artery) joined to the ulnar artery was used as a replacement for the resected distal radius, thereby creating a new wrist joint. Excellent graft survivals were observed in all four cases. The wrists, when assessed 24-48 months after surgery, were found to have good ranges of movement, although with mild dorsal subluxation. These results compared well with other means of wrist reconstruction (i.e., the vascularized fibular graft). Although conventional means of arthrodesis give acceptable hand function, the absence of wrist motion is unacceptable to the young and active, who may prefer the method described in this article.

[Effect of strophanthin and celanide on the autoregulation of the cerebral blood flow]

It has been demonstrated in acute experiments on anesthetized cats that the control group animals manifested (before glycoside administration) a comparatively steady brain circulation accompanied by changes in the arterial pressure (AP) within 60-150 mm Hg. Intravenous injection of strophanthine (0.05 mg/kg) and celanide (0.1 mg/kg) improved autoregulatory reaction of the brain vessels during AP falling to lower levels as compared to control.