Avinoam Nevler

Posttranscriptional Upregulation of IDH1 by HuR Establishes a Powerful Survival Phenotype in Pancreatic Cancer Cells

Cancer aggressiveness may result from the selective pressure of a harsh nutrient-deprived microenvironment. Here we illustrate how such conditions promote chemotherapy resistance in pancreatic ductal adenocarcinoma (PDAC). Glucose or glutamine withdrawal resulted in a 5- to 10-fold protective effect with chemotherapy treatment. PDAC xenografts were less sensitive to gemcitabine in hypoglycemic mice compared with hyperglycemic mice. Consistent with this observation, patients receiving adjuvant gemcitabine (n = 107) with elevated serum glucose levels (HgbA1C > 6.5%) exhibited improved survival. We identified enhanced antioxidant defense as a driver of chemoresistance in this setting. ROS levels were doubled in vitro by either nutrient withdrawal or gemcitabine treatment, but depriving PDAC cells of nutrients before gemcitabine treatment attenuated this effect. Mechanistic investigations based on RNAi or CRISPR approaches implicated the RNA binding protein HuR in preserving survival under nutrient withdrawal, with or without gemcitabine. Notably, RNA deep sequencing and functional analyses in HuR-deficient PDAC cell lines identified isocitrate dehydrogenase 1 (IDH1) as the sole antioxidant enzyme under HuR regulation. HuR-deficient PDAC cells lacked the ability to engraft successfully in immunocompromised mice, but IDH1 overexpression in these cells was sufficient to fully restore chemoresistance under low nutrient conditions. Overall, our findings highlight the HuR-IDH1 regulatory axis as a critical, actionable therapeutic target in pancreatic cancer. Cancer Res; 77(16); 4460-71. ©2017 AACR.

CRISPR Knockout of the HuR Gene Causes a Xenograft Lethal Phenotype

Pancreatic ductal adenocarcinoma (PDA) is the third leading cause of cancer-related deaths in the United States, whereas colorectal cancer is the third most common cancer. The RNA-binding protein HuR (ELAVL1) supports a pro-oncogenic network in gastrointestinal (GI) cancer cells through enhanced HuR expression. Using a publically available database, HuR expression levels were determined to be increased in primary PDA and colorectal cancer tumor cohorts as compared with normal pancreas and colon tissues, respectively. CRISPR/Cas9 technology was successfully used to delete the HuR gene in both PDA (MIA PaCa-2 and Hs 766T) and colorectal cancer (HCT116) cell lines. HuR deficiency has a mild phenotype, in vitro, as HuR-deficient MIA PaCa-2 (MIA.HuR-KO(−/−)) cells had increased apoptosis when compared with isogenic wild-type (MIA.HuR-WT(+/+)) cells. Using this isogenic system, mRNAs were identified that specifically bound to HuR and were required for transforming a two-dimensional culture into three dimensional (i.e., organoids). Importantly, HuR-deficient MIA PaCa-2 and Hs 766T cells were unable to engraft tumors in vivo compared with control HuR-proficient cells, demonstrating a unique xenograft lethal phenotype. Although not as a dramatic phenotype, CRISPR knockout HuR HCT116 colon cancer cells (HCT.HuR-KO(−/−)) showed significantly reduced in vivo tumor growth compared with controls (HCT.HuR-WT(+/+)). Finally, HuR deletion affects KRAS activity and controls a subset of pro-oncogenic genes. Implications: The work reported here supports the notion that targeting HuR is a promising therapeutic strategy to treat GI malignancies. Mol Cancer Res; 15(6); 696–707. ©2017 AACR.

Diverticulitis: does age matter?

Acute diverticulitis has been traditionally associated with worse outcome in young patients, indicating a more aggressive surgical approach is required for them. The aim of this study was to assess whether acute diverticulitis was more virulent in young patients.

Early Experience with Laparoscopic Lavage in Acute Complicated Diverticulitis

Background: Contemporary surgical management of complicated diverticulitis is controversial. Traditionally, the gold standard has been resection and colostomy, but recently peritoneal lavage and drainage without resection in cases of purulent peritonitis have been suggested. This study aims to review our initial experience with laparoscopic peritoneal lavage for complicated diverticulitis. Methods: Retrospective review of all patients who underwent emergent peritoneal lavage and drainage for acute complicated diverticulitis. Results: Five-hundred-thirty-eight patients admitted for acute diverticulitis between 2007 and 2012 were recorded in the database. Thirty seven underwent emergent surgery of which 10 had peritoneal lavage and drainage without colonic resection for complicated diverticulitis causing peritonitis. Peritoneal lavage and drainage resulted in the resolution of acute symptoms in all cases. In long-term follow-up, 3 (30%) patients required elective resection owing to symptomatic disease, two of these due to recurrent diverticulitis, and one owing to complicated fistula following the procedure. Conclusion: Peritoneal lavage is a feasible option for complicated diverticulitis with purulent non-fecal peritonitis, but a significant portion of the patients may require elective resection. Comparative studies with emergent resection are needed to determine the role of peritoneal lavage in complicated diverticulitis.

A Sub-Type of Familial Pancreatic Cancer: Evidence and Implications of Loss-of-Function Polymorphisms in Indoleamine-2,3-Dioxygenase-2.

BACKGROUND Variation in an individual’s genetic status can impact the development of pancreatic ductal adenocarcinoma; however, the m ajority of familial pancreatic cancers (FPC) cannot yet be attributed to a specific inherited mutation. We present data suggesting a correlation between loss-of-function single nucleotide polymorphisms (SNPs) in an immune regulator gene, indoleamine-2,3-dioxygenase-2 (IDO2), and an increased risk of FPC. STUDY DESIGN Germline DNA from patients who underwent resection for pancreatic ductal adenocarcinoma (n = 79) was sequenced for the IDO2 SNPs R248W and Y359Stop. Genotypes resulting in inactivation of IDO2 (Y325X homozygous, R248W homozygous) were labeled as homozygous, and the other genotypes were grouped as wild-type or heterozygous. Genotype distributions of each SNP were analyzed for Hardy-Weinberg deviation. A genotype frequency set from the 1000 Genomes Project (n = 99) was used as a genetic control for genotype distribution comparisons. RESULTS A significant 2-fold increase in the overall prevalence of the Y359Stop homozygous genotype compared with the expected Hardy-Weinberg equilibrium was noted (p < 0.05). Familial pancreatic cancer was noted in 15 cases (19%) and comparison of the FPC cohort set to the genetic control set showed a 3-fold increase in Y359Stop homozygous rates (p = 0.054). Overall in our cohort, the homozygous genotype group was associated with increased risk of FPC (odds ratio 5.4; 95% CI 1.6 to 17.6; p < 0.01). Sex, age at diagnosis, and history of tobacco use were not found to be significantly associated with FPC. CONCLUSIONS Our preliminary data suggest a strong association between the IDO2 inactivating Y359Stop SNP and an increased risk of FPC when compared with the control group. Future studies will evaluate the value of IDO2 genotyping as a prognostic, early detection marker for pancreatic ductal adenocarcinoma and a predictive marker for novel immune checkpoint therapies.

Assessment of Gel-Coated Delayed Self-Gripping Mesh

BACKGROUND Mesh hernia repair is one of the most frequently performed procedures in general surgery. Recently, use of the self-gripping mesh demonstrated a beneficial effect on postoperative pain in inguinal hernia repairs. However, in intra-abdominal placement, the use of this novel mesh requires greater laparoscopic skill and dexterity because of the meshs tendency to fold and adhere to itself and to any surrounding tissues. We hypothesized that gel-like coverage of a self-gripping mesh with a water-soluble film would allow delaying the immediate surface adhesion of the mesh to the tissue, which may allow greater freedom and ease in mesh placement for laparoscopic surgeons. METHODS In this ex vivo animal study, gel-coated self-gripping mesh (ProGrip) was compared with a control uncoated mesh in bovine and porcine tissue specimens and assessed for dislodgement shear forces before and after dissolving of the gel. RESULTS Gel coating of the mesh reduced preperitoneal dislodgement forces in a porcine abdominal wall specimen by 81% (8.05 ± 0.66 vs 1.53 ± 0.82 N, P < .01). Dissolving the gel markedly increased the anchoring forces (10.62 ± 3.70 vs 1.53 ± 0.82 N, P < .0001), and after dissolving the gel, the mesh shear dislodgement forces were similar and noninferior to the control mesh (8.05 ± 0.66 vs 10.62 ± 3.70 N, P = NS). CONCLUSIONS We believe that water-soluble gel coating does not impair the adhesive features of the self-gripping mesh and may simplify its use in open and laparoscopic procedures by allowing controlled activation of the self-gripping mechanism.

The effects of hormonal replacement therapy (HRT) on mammographic breast density and abnormal mammograms prompting further investigation.

8 Background: Mammographic density has been associated with higher risk of breast cancer and lower sensitivity. HRT has been implicated with increased density and is also a risk factor. The relationship between HRT, breast density, and mammographic findings requiring investigation has not been fully investigated. We aimed at analyzing this correlation. METHODS 2,758 consecutive, single-center screening mammograms performed during 1 year were analyzed. Mammograms were supplemented by ultrasound. Density was measured by a semiquantitative, 5-grade scale, and grouped into low (1-3) (LDM) and high density (4-5) (HDM). Demographic and obstetric data, personal and family history of breast cancer, and the use of HRT were entered into database. These parameters were correlated with breast density and any abnormality detected. Univariate and multivariate analysis as well as multivariate logistic regression were performed on SAS 9.2. RESULTS Mean overall age was 48 (SD = 10.8, range 27-78), mean ages of LDM and HDM groups were 59 ± 10.5 and 50.9 ± 9.3 respectively (p = 0.001). Of 2,758 tests, 2,094 (76%) were LDM and 664 (24%) were HDM. 1,962 women (71%) were postmenopausal and 592 (30%) were on HRT. A difference in density between pre- and postmenopausal women was observed (p = 0.0001). HRT was not associated with higher rate of HDM (18%, n = 105/582) vs.15% n = 211/1370 (p = n.s) without HRT. Abnormality was more likely in postmenopausal HRT-less (52% n = 711/1370) vs. (30% n = 226/582) HRT (p = 0.0001) including solid lump (p = 0.0001), tissue irregularity (p = 0.016) and calcifications (p = 0.0005). Menopause was associated with 48% of any finding vs. 41.4% in pre-menopause women (p = 0.0017). 104 malignant lesions were found in 267 with mammographic findings prompting histological assessment. HRT was associated with lower incidence (28%) of malignancy compared to 50% without HRT. CONCLUSIONS HRT was not associated with increased density nor with higher risk of malignancy; moreover, a lower rate of mammographic abnormality was noted. Albeit further studies are required, the results of this study do not support the notion that HRT increases the likelihood of malignancy or affects breast density.