Abstract 1466: MYC localizes to the nuclear pore to promote DNA repair during replication stress

Genomic instability is a hallmark of cancer which promotes oncogenic mutations in pancreatic ductal adenocarcinoma (PDAC), leading to more aggressive tumors with greater potential for drug resistance. Deregulation of the master transcription factor, MYC, is found in virtually all PDAC tumors and promotes genomic alterations by increasing replication stress, augmenting DNA repair pathways, and promoting cell survival. To resolve replication stress, stalled forks are trafficked to the nuclear pores where the necessary machinery accumulates. Activated MYC is spatially reorganized to the nuclear pores as well, a mechanism that is exacerbated in cancer. Whether MYC activity at the nuclear pores contributes to resolving replication stress in PDAC remains to be known. To investigate this mechanism, we are creating genomic and proteomic tools to determine MYC’s function at the nuclear pores during replication stress induced by olaparib treatment in PDAC cells. We found that olaparib significantly increases MYC accumulation at the nuclear pore in low-passage cell lines we established from PDAC patient tumors. Furthermore, we showed that MYC interacts with the nuclear pore resident SUMO protease, SENP1, which plays a key role in resolving stalled forks. Our preliminary data suggest a role for MYC resolving replication stress at nuclear pores, and could indicate MYC activity as a therapeutic target in olaparib-resistant PDAC.

Citation Format: Gabriel Cohn, Colin J. Daniel, Daniel F. Liefwalker, Rosalie C. Sears. MYC localizes to the nuclear pore to promote DNA repair during replication stress [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1466.

Pathophysiology and treatment of the dyslipidemia of insulin resistance

Insulin resistance, and the compensatory hyperinsulinemia that results, has been linked to a host of defects including glucose intolerance, diabetes, hypertension, dyslipidemia, endothelial dysfunction, impaired fibrinolysis, and subclinical inflammation. Patients with this metabolic syndrome have a markedly increased risk for the development of atherothrombotic cardiovascular disease. The characteristic dyslipidemia of insulin resistance consists of elevated triglyceride and triglyceride-rich lipoprotein levels, low levels of high-density lipoprotein cholesterol, and increased concentrations of small, dense low-density lipoprotein cholesterol. Management of this dyslipidemia typically involves a dual approach. Lifestyle modification is an essential component of any successful treatment plan, but alone is usually insufficient to correct these lipoprotein abnormalities. Medications that diminish insulin resistance and directly alter lipoproteins are also necessary in the majority of cases. Combinations of therapeutic agents are often required to optimize attainment of treatment goals.

Pseudoventricular fibrillation

A case of atrial fibrillation with asystole was diagnosed as ventricular fibrillation because of the autogain feature of the electrocardiographic monitor. Direct current shock therapy was withheld only because the patient regained consciousness.

Lipid disorders: justification of methods and goals of treatment

Dyslipidemia is a major risk factor for coronary heart disease (CHD). While some uncertainty exists about the clinical significance of improving high-density lipoprotein cholesterol and triglyceride levels, large primary- and secondary-prevention studies aimed at lowering low-density lipoprotein cholesterol levels with statins have convincingly reduced CHD events and total mortality. Despite the strong clinical evidence and widely publicized treatment guidelines, many hyperlipidemic patients receive inadequate lipid-lowering treatment. This failure to achieve clinical treatment goals may be due to poor physician adherence to treatment guidelines, patient noncompliance, and the presence of concomitant medical conditions that modify typical hyperlipidemia management. This review considers the challenges and available strategies to optimize lipid management in patients at risk for CHD.

De novo translocation (8;12) and frontofacionasal dysplasia in a newborn boy

We describe a newborn boy one of triplets, whose karyotype was 46,XY, t(8;12)(q22;q21). Prenatal diagnosis of multiple craniofacial anomalies had been made. Following delivery, the patient was thought to exhibit findings consistent with a diagnosis of frontofacionasal dysostosis. We hypothesize that one of the break points of this translocation may involve a gene essential to craniofacial development.

Medical therapy versus coronary angioplasty in stable coronary artery disease: a critical review of the literature

The recent publication of the Atorvastatin Versus Revascularization Treatment (AVERT) trial has renewed debate on the optimal management strategy for relatively stable patients with coronary artery disease. Currently, coronary angiography and percutaneous coronary intervention are often performed in stable patients with good exercise tolerance who have not been treated with proven medications such as aspirin, statins and beta-adrenergic blocking agents in conjunction with comprehensive lifestyle modification. We review the results of prior trials comparing medical therapy with angioplasty and assess their strengths and limitations and then make conclusions about the aggregate data. Next, we describe the ongoing Clinical Outcome Utilizing Revascularization and Aggressive Drug Evaluation (COURAGE) trial, which will be the largest of the studies comparing optimal medical therapy and percutaneous revascularization. This study will employ intensive medical management in all patients with coronary disease, and the incremental benefit of state of the art revascularization techniques in terms of clinical event reduction, quality of life issues and cost-effectiveness will be addressed. For now, aggressive medical therapy and revascularization should be viewed as complementary rather than opposing strategies. All patients with coronary heart disease should receive proven medical and lifestyle prescriptions to favorably alter the atherosclerotic process. Percutaneous revascularization without comprehensive risk factor modification is a suboptimal therapeutic strategy.

Parvoviral infection associated with increased nuchal translucency: a case report

An increased fetal nuchal translucency detected by first trimester ultrasound has been associated with an elevated risk of aneuploidy. The etiology of the increased nuchal translucency in fetuses with normal chromosomes is uncertain, but it has been associated with poor pregnancy outcome. We report a fetus with increased nuchal translucency and a normal karyotype, in which parvovirus was detected by polymerase chain reaction in the amniotic fluid. Although an ultrasound detected an increased nuchal fold thickness in the second trimester, the pregnancy was otherwise uncomplicated. Parvovirus should be considered as a possible etiology of increased nuchal translucency. The risks to a fetus with first trimester parvovirus infections diagnosed under these conditions are uncertain and require larger studies.

A comparison of laboratory data in perinatal transfers at Baystate Medical Center and transferring hospitals

Objective: Perinatal transfers come to Baystate Medical Center (BMC), a tertiary hospital with level III nursery, for treatment of pregnancy-related complications such as preterm labor, PPROM, PIH, diabetes, and bleeding problems. We postulated that Baystate Medical Center, a teaching hospital, must repeat most of the laboratory tests ordered by the community hospitals transferring these pregnant patients.Methods: A comparison of laboratory tests ordered by the transferring hospital and Baystate Medical Center was done in a retrospective chart review. Among the 92 charts reviewed, 42 perinatal transfer patients with PTL and PPROM, excluding patients with diabetes, PIH, and other complications, were included in the study.Results: A significant difference (P <.001 by Student t test) was found between the number of laboratory tests ordered by Baystate Medical Center and the outside hospital. Ten laboratory tests, such as white count, hematocrit, differential, cervical cultures, urinalysis and culture, tox screen, type and screen, and ultrasounds, were ordered by BMC in comparison to only three laboratory tests ordered by the transferring doctors. In comparing patients directly admitted to Baystate for PTL or PPROM with the perinatal transfer patients, there was no significant difference between the number of laboratory tests ordered. However, perinatal transfers had a greater percentage of PPROM and delivery prior to 36 weeks.Conclusion: In conclusion, there is limited redundancy in laboratory testing in perinatal transfer patients when they are transferred from one institution to the another. Diagnosis of PTL is difficult and a panel of laboratory tests have become standards in finding causes at BMC. Allowing the tertiary hospital to work up the perinatal transfer patients is an efficient way of allocating health care.

Transplantation of unrelated cord blood cells

A 43-year-old woman with Philadelphia chromosome (Ph) positive chronic myelogenous leukemia in acute phase received high-dose chemotherapy followed by transfusion of 12 randomly selected units of umbilical cord blood. HLA analysis showed cells of one donor from day +10 to day +43 post-transfusion. This unit was HLA class II identical with that of the patient.

Reproduction in a patient with trisomy 8 mosaicism: case report and literature review

We describe a patient with trisomy 8 mosaicism followed through a sixth pregnancy and discuss issues in phenotypic and genotypic variability, the risk for neoplasia, and reproductive risks.

Predictors of crop diversification: a survey of tobacco farmers in North Carolina (USA)

OBJECTIVE

To assess the attitudes and behaviours of North Carolina tobacco farmers around crop diversification.

DESIGN

Cross-sectional telephone survey.

PARTICIPANTS

Active tobacco farmers in 14 North Carolina counties (n = 1236), interviewed between January and April 1997 (91% response rate).

OUTCOME MEASURES

Interest in, experience with, and perceived barriers to diversification.

RESULTS

Most farmers (95%) grew/raised a commodity other than tobacco (mean = 2.8). A total of 60% of farmers expressed interest in trying other on-farm activities to supplement their tobacco and 60% reported taking action in the past year around supplementation. Younger age and college education were positively associated with interest. College education, off-farm income, and larger farm size were associated with the number of actions taken. For perceived external barriers to diversification, use of tobacco, percent income from tobacco, lack of college education, and younger age were most strongly associated with the number of barriers. For internal barriers (personal factors), percent income from tobacco, use of tobacco, and lack of college education were most strongly associated with the number of barriers.

CONCLUSIONS

Most farmers were involved in diverse operations and expressed interest in continuing to diversify, although the breadth of diversification was narrow. Farmers noted many barriers to diversifying. If conventional production and marketing techniques are employed for non-tobacco alternatives, these alternatives may not provide the sustainable profitability that tobacco has afforded. Competition from foreign tobacco growers is the primary threat to the future of American growers and tobacco dependent communities.

Jaundice induced by streptokinase

Streptokinase is the mainstream therapy for acute myocardial infarction. A fifty-seven-year-old man with acute MI was admitted to the intensive cardiac care unit and received streptokinase and heparin. At the time of admission, he was not receiving any drugs and denied any previous exposure to a hepatotoxic agent. Five hours later he developed a dramatic hypersensitivity reaction including high fever, pulmonary edema, cyanosis, and convulsions. Within twelve hours, his clinical state was stabilized. After forty-eight hours, he developed jaundice and transaminasemia, which subsided by the eighth day. Only a few reports of overt jaundice are associated with streptokinase.

Missense mutations in the beta-myosin heavy-chain gene cause central core disease in hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is an important cause of sudden death in apparently healthy young individuals. In less than half of kindreds with HCM, the disease is linked to the beta-myosin heavy-chain gene locus (MYH7). We have recently described two missense MYH7 gene mutations [Arg-403 to Gln (R403Q) and Leu-908 to Val (L908V)] and found that the mutant message is present in skeletal muscle soleus) and that the mutant beta-myosin obtained from soleus muscle has abnormal in vitro motility activity. Having identified a second kindred with the R403Q mutation, and 3 other kindreds with two additional mutations (G741R and G256E), we performed histochemical analysis of soleus muscle biopsies from 25 HCM patients with one of these four mutations. Light microscopic examination of the NADH-stained biopsies revealed the presence of central core disease (CCD) of skeletal muscle, a rare autosomal dominant nonprogressive myopathy characterized by a predominance of type I "slow" fibers and an absence of mitochondria in the center of many type I fibers. CCD was present in 10 of 13 patients with the L908V mutation, 5 of 8 patients with the R403Q mutation, 1 of 3 patients with the G741R mutation, and 1 patient with the G256E mutation. Mild-to-moderate myopathic changes with muscle fiber hypertrophy were present in 16 patients. Notably, CCD was present in 2 adults and 3 children with the L908V mutation who did not have cardiac hypertrophy. In contrast, soleus muscle samples from 5 patients from 4 kindreds in which HCM was not linked to the MYH7 locus showed no myopathy or CCD. Soleus muscle biopsies from 5 control subjects also showed normal histology. This work demonstrates that (i) MYH7-associated HCM is often a disease of striated muscle but with predominant cardiac involvement and (ii) a subset of HCM patients with MYH7 gene missense mutations have CCD.

Argon laser laparoscopy for treatment of pelvic endometriosis associated with infertility and pelvic pain

Argon laser laparoscopy was used for treatment of 46 patients with pelvic endometriosis. Infertility was the primary diagnosis in 31 patients, and pelvic pain was the primary diagnosis in 21 patients. A 600 mum laser fiber was used through the operative channel of the laparoscope, and the tip of the fiber was kept at a distance of 2-3 mm from the lesions. The power density used varied between 1604 and 1069 W/cm 2 at the tissue level. The pregnancy rate following treatment of the infertile group was 42%. Eighty-four percent of these pregnancies occurred within the first 8 months of treatment. In the group with pelvic pain, 8 patients experienced complete pain relief, and 13 patients experienced partial pain relief. Difficulties with the use of the fiber included breakage in 3 patients and melting of the fiber tip in 1 patient.

Quantitative evaluation of the skin and accessory appendages in vulvar carcinoma in situ

Fifty cases of vulvar carcinoma in situ comprising over 1000 histologic sections were studied. Each case was evaluated to determine the thickness of the neoplastic epidermis and the depth of involved skin appendages. Two precise techniques were used to perform the microscopic measurements. The areas most frequently afflicted with neoplasia were: one or both labia (45%), interlabial folds (27%), perineum-fourchette (15%), and perianal skin (10%). Multicentric disease was observed in 68% of the cases. The epidermal thickness ranged between 0.35-1.66 mm. The mean depth (+/- SD) of the epidermis was 0.93 +/- 0.37 mm. Eighteen of the 50 patients demonstrated involvement of the skin appendages to a mean depth of 1.53 +/- 0.77 mm, suggesting that laser vaporization to a depth of 2.5 mm will, with the anticipated additional thermal necrosis, eliminate appendages involved with carcinoma in situ in 95% of instances. The most common sites of skin appendage involvement were the labia majora or minora and the interlabial folds.

Electron spinal resonance analysis of the nitroxide spin label 2,2,6,6-tetramethylpipidone-N-oxyl (Tempone) in single crystals of the reduced Tempone matrix

The nitroxide spin label Tempone (2,2,6,6-tetramethylpiperidone-N-oxyl) can be reduced with ascorbic acid to give a nonparamagnetic species. Single crystals of reduced Tempone serve as a suitable host matrix to orient trace quantities of Tempone for ESR analysis. In these crystals the majority of the Tempone molecules are well-oriented, but a smaller fraction of the molecules tumble freely to give an isotropic electron spin resonance (ESR) spectrum. ESR transitions for the oriented molecules are saturated at much lower microwave power levels than for the tumbling molecules. For the oriented molecules, an analysis of the anisotropy of the spectroscopic splitting factor (g) gives principal values of g(1) = 2.0094, g(2) = 2.0061, g(3) = 2.0021. The hyperfine coupling tensor is nearly axially symmetric, with principal values (in gauss) of A(1) = 6.5, A(2) = 6.7, A(3) = 33.0. Within experimental error, the principal axis systems for the g tensor and the hyperfine tensor are identical. Comparison of the average values of g and A with the isotropic values of these parameters for Tempone in solvents of different polarity suggests a method for choosing the most appropriate tensor elements to be used for spin label experiments in various solvent systems.