Roles of Necroptosis, Apoptosis, and Inflammation in Colorectal Carcinogenesis: A Longitudinal Human Study

AUTHORS

Timothy Su, Xiangzhu Zhu, Yong Li, Chang Yu, Xinqing Deng, Eugene Shubin, Lifang Hou, Jing Zhao, Lei Fan, Heping Zhang, Harvey J. Murff, Reid M. Ness, Martha J. Shrubsole, Qi Dai

ABSTRACT

Necroptosis triggers an inflammatory cascade associated with antimicrobial defense. No prospective human study has yet explored the role of necroptosis in colorectal cancer development. We conducted quantitative analysis of biomarkers for necroptosis [transient receptor potential cation channel subfamily M member 7 (TRPM7) and phosphorylated mixed lineage kinase domain-like protein], inflammation [cyclooxygenase-2 (COX-2)], apoptosis [BCL2-associated X (BAX) and terminal deoxynucleotidyl transferase dUTP nick end labeling], and cell proliferation (Ki67). This was done using tissue microarray biospecimens from the Cooperative Human Tissue Network and rectal biopsies from a longitudinal study within the Personalized Prevention of Colorectal Cancer Trial. In the human colorectal adenoma–carcinoma sequence, we observed an inverse expression trend between BAX and TRPM7; TRPM7 decreased from normal mucosa to small and large adenomas but significantly increased in early colorectal cancer stages (Ptrend = 0.004). It maintained high levels through all cancer stages. An increased COX-2 intensity in the epithelium was noted during tumorigenesis (Ptrend = 0.02) and was significantly associated with an elevated risk of metachronous polyps (odds ratio = 3.04; 95% confidence interval, 1.07–8.61; Ptrend = 0.02). The combined composite index scores of TRPM7 and COX-2 were strongly linked to 6- to 47-fold increased risks for metachronous adenoma/serrated polyps, whereas combined scores of phosphorylated mixed lineage kinase domain-like protein or TRPM7 with BAX were associated with an 11.5- or 13.3-fold elevated risk for metachronous serrated polyps. In conclusion, our findings suggest that COX-2 expression within normal-looking colorectal mucosa is significantly associated with an increased risk of metachronous colorectal polyp. Furthermore, our results propose the hypothesis that synergistic interactions among necroptosis, inflammation, and apoptosis could play a pivotal role in human colorectal tumorigenesis.

Prevention Relevance: Our findings suggest that COX-2 expression and combined scores of COX-2, TRPM7, and BAX hold promise for predicting the risk of metachronous polyps and could potentially serve as a tool for assessing the effectiveness of chemopreventive agents in preventing colorectal cancer during intervention trials.

Skeletal abnormalities in mice with Dnmt3a missense mutations

AUTHORS

Austin Bell-Hensley, Diana C. Beard, Kathryn Feeney, Hongjun Zheng, Yunhao Jiang, Xiyun Zhang, Jin Liu, Harrison Gabel, Audrey McAlinden

ABSTRACT

Overgrowth and intellectual disability disorders in humans are typified by length/height and/or head circumference ≥ 2 standard deviations above the mean as well as intellectual disability and behavioral comorbidities, including autism and anxiety. Tatton-Brown-Rahman Syndrome is one type of overgrowth and intellectual disability disorder caused by heterozygous missense mutations in the DNA methyltransferase 3A (DNMT3A) gene. Numerous DNMT3A mutations have been identified in Tatton-Brown-Rahman Syndrome patients and may be associated with varying phenotype severities of clinical presentation. Two such mutations are the R882H and P904L mutations which result in severe and mild phenotypes, respectively. Mice with paralogous mutations (Dnmt3aP900L/+ and Dnmt3aR878H/+) exhibit overgrowth in their long bones (e.g., femur, humerus), but the mechanisms responsible for their skeletal overgrowth remain unknown. The goal of this study is to characterize skeletal phenotypes in mouse models of Tatton-Brown-Rahman Syndrome and identify potential cellular mechanisms involved in the skeletal overgrowth phenotype. We report that mature mice with the Dnmt3aP900L/+ or Dnmt3aR878H/+ mutation exhibit tibial overgrowth, cortical bone thinning, and weakened bone mechanical properties. Dnmt3aR878H/+ mutants also contain larger bone marrow adipocytes while Dnmt3aP900L/+ mutants show no adipocyte phenotype compared to control animals. To understand the potential cellular mechanisms regulating these phenotypes, growth plate chondrocytes, osteoblasts, and osteoclasts were assessed in juvenile mutant mice using quantitative static histomorphometry and dynamic histomorphometry. Tibial growth plates appeared thicker in mutant juvenile mice, but no changes were observed in osteoblast activity or osteoclast number in the femoral mid-diaphysis. These studies reveal new skeletal phenotypes associated with Tatton-Brown-Rahman Syndrome in mice and provide a rationale to extend clinical assessments of patients with this condition to include bone density and quality testing. These findings may be also informative for skeletal characterization of other mouse models presenting with overgrowth and intellectual disability phenotypes.

Metabolism and Disposition of the Novel Oral Factor XIa Inhibitor Asundexian in Rats and in Humans

AUTHORS

Isabel Piel, Anna Engelen, Dieter Lang, Simone I. Schulz, Michael Gerisch, Christine Brase, Wiebke Janssen, Lukas Fiebig, Stefan Heitmeier & Friederike Kanefendt

ABSTRACT

Background and Objectives

Current anticoagulants pose an increased risk of bleeding. The development of drugs targeting factor XIa, like asundexian, may provide a safer treatment option. A human mass‑balance study was conducted to gain a deeper understanding of the absorption, distribution, metabolism, excretion, and potential for drug–drug interaction of asundexian. Additionally, an overview of the biotransformation and clearance pathways for asundexian in humans and bile-duct cannulated (BDC) rats in vivo, as well as in vitro in hepatocytes of both species, is reported.

Methods

The mass balance, biotransformation, and excretion pathways of asundexian were investigated in six healthy volunteers (single oral dose of 25 mg [14C]asundexian) and in BDC rats (intravenous [14C]asundexian 1 mg/kg).

Results

Overall recovery of radioactivity was 101% for humans (samples collected up to 14 days after dosing), and 97.9% for BDC rats (samples collected in the 24 h after dosing). Radioactivity was mainly excreted into feces in humans (80.3%) and into bile/feces in BDC rats (> 94%). The predominant clearance pathways in humans were amide hydrolysis to metabolite M1 (47%) and non-labeled M9 with subsequent N-acetylation to M10; oxidative biotransformation was a minor pathway (13%). In rats, hydrolysis of the terminal amide to M2 was the predominant pathway. In human plasma, asundexian accounted for 61.0% of total drug-related area under the plasma concentration–time curve (AUC); M10 was the major metabolite (16.4% of the total drug-related AUC). Excretion of unmetabolized drug was a significant clearance pathway in both species (human, ~ 37%; BDC rat, ~ 24%). The near-complete bioavailability of asundexian suggests negligible limitations on absorption and first-pass metabolism. Comparison with radiochromatograms from incubations with human or rat hepatocytes indicated consistency across species and a good overall in vitro/in vivo correlation.

Conclusions

Similar to preclinical experiments, total asundexian-derived radioactivity is cleared quantitatively predominantly via feces. Excretion occurs mainly via amide hydrolysis and as the unchanged drug.

Regional Gene Therapy with Transduced Human Cells: The Influence of “Cell Dose” on Bone Repair

AUTHORS

Hansel Ihn, Hyunwoo Kang, Brenda Iglesias, Osamu Sugiyama, Amy Tang, Roger Hollis, Sofia Bougioukli, Tautis Skorka, Sanghyun Park, Donald Longjohn, Daniel A. Oakes, Donald B. Kohn, and Jay R. Lieberman

ABSTRACT

Regional gene therapy using a lentiviral vector containing the BMP-2 complementary DNA (cDNA) has been shown to heal critical-sized bone defects in rodent models. An appropriate “cellular dose” needs to be defined for eventual translation into human trials. The purpose of this study was to evaluate bone defect healing potential and quality using three different doses of transduced human bone marrow cells (HBMCs). HBMCs were transduced with a lentiviral vector containing either BMP-2 or green fluorescent protein (GFP). All cells were loaded onto compression-resistant matrices and implanted in the bone defect of athymic rats. Treatment groups included femoral defects that were treated with a low-dose (1 × 106 cells), standard-dose (5 × 106 cells), and high-dose (1.5 × 107 cells) HBMCs transduced with lentiviral vector containing BMP-2 cDNA. The three control groups were bone defects treated with HBMCs that were either nontransduced or transduced with vector containing GFP. All animals were sacrificed at 12 weeks. The bone formed in each defect was evaluated with plain radiographs, microcomputed tomography (microCT), histomorphometric analysis, and biomechanical testing. Bone defects treated with higher doses of BMP-2-producing cells were more likely to have healed (6/14 of the low-dose group; 12/14 of the standard-dose group; 14/14 of the high-dose group; χ2(2) = 15.501, p < 0.001). None of the bone defects in the control groups had healed. Bone defects treated with high dose and standard dose of BMP-2-producing cells consistently outperformed those treated with a low dose in terms of bone formation, as assessed by microCT and histomorphometry, and biomechanical parameters. However, statistical significance was only seen between defects treated with high dose and low dose. Larger doses of BMP-2-producing cells were associated with a higher likelihood of forming heterotopic ossification. Femurs treated with a standard- and high-dose BMP-2-producing cells demonstrated similar healing and biomechanical properties. Increased doses of BMP-2 delivered through higher cell doses have the potential to heal large bone defects. Adapting regional gene therapy for use in humans will require a balance between promoting bone repair and limiting heterotopic ossification.

RSPO3 is important for trabecular bone and fracture risk in mice and humans

AUTHORS

Karin H. Nilsson, Petra Henning, Maha El Shahawy, Maria Nethander, Thomas Levin Andersen, Charlotte Ejersted, Jianyao Wu, Karin L. Gustafsson, Antti Koskela, Juha Tuukkanen, Pedro P. C. Souza, Jan Tuckermann, Mattias Lorentzon, Linda Engström Ruud, Terho Lehtimäki, Jon H. Tobias, Sirui Zhou, Ulf H. Lerner, J. Brent Richards, Sofia Movérare-Skrtic & Claes Ohlsson

ABSTRACT

With increasing age of the population, countries across the globe are facing a substantial increase in osteoporotic fractures. Genetic association signals for fractures have been reported at the RSPO3 locus, but the causal gene and the underlying mechanism are unknown. Here we show that the fracture reducing allele at the RSPO3 locus associate with increased RSPO3 expression both at the mRNA and protein levels, increased trabecular bone mineral density and reduced risk mainly of distal forearm fractures in humans. We also demonstrate that RSPO3 is expressed in osteoprogenitor cells and osteoblasts and that osteoblast-derived RSPO3 is the principal source of RSPO3 in bone and an important regulator of vertebral trabecular bone mass and bone strength in adult mice. Mechanistic studies revealed that RSPO3 in a cell-autonomous manner increases osteoblast proliferation and differentiation. In conclusion, RSPO3 regulates vertebral trabecular bone mass and bone strength in mice and fracture risk in humans.

N-3 Long Chain Fatty Acids Supplementation, Fatty Acids Desaturase Activity, and Colorectal Cancer Risk: A Randomized Controlled Trial

AUTHORS

Harvey J. Murff, Martha J. Shrubsole, Qiuyin Cai, Timothy Su, Jennings H. Dooley, Sunny S. Cai, Wei Zheng & Qi Daic

ABSTRACT

Introduction

n-3 long-chain polyunsaturated fatty acids (LCPUFA) have anti-inflammatory effects and may reduce colorectal cancer risk. The purpose of this study was to evaluate the effects of n-3 LCPUFA supplementation on markers of rectal cell proliferation and apoptosis and examine how genetic variation in desaturase enzymes might modify this effect.

Methods

We conducted a randomized, double-blind, control six-month trial of 2.5 grams of n-3 LCPUFA per day compared to olive oil. Study participants had a history of colorectal adenomas. Randomization was stratified based on the gene variant rs174535 in the fatty acid desaturase 1 enzyme (FADS1). Our primary outcome was change in markers of rectal epithelial proliferation and apoptosis.

Results

A total of 141 subjects were randomized. We found no difference in apoptosis markers between participants randomized to n-3 LCPUFA compared to olive oil (P = 0.41). N-3 LCPUFA supplementation increased cell proliferation in the lower colonic crypt compared to olive oil (P = 0.03) however baseline indexes of proliferation were different between the groups at randomization. We found no evidence that genotype modified the effect.

Conclusions

Our study did not show evidence of a proliferative or pro-apoptotic effect on n-3 LCPUFA supplementation on rectal mucosa regardless of the FADS genotype.