Abstract 4637: Non-stem cell-driven colonic tumors retain an intestinal differentiation hierarchy

Colorectal cancer (CRC) is the third leading cause of cancer mortality in the United States. Cancer stem cells (CSCs) play critical roles in therapeutic resistance, tumor recurrence, and metastasis that lead to patient death. We propose to evaluate the properties of CSCs in the context of the tumor cell-of-origin, the cell that initiates oncogenesis. We hypothesize that the tumor cell-of-origin is directly related to the CSCs present in tumors that consequently arise. To test this hypothesis, the stem-like properties of CSCs from stem cell- and non-stem cell-driven tumors, initiated from the Lrig1 and Mist1 promoters, respectively, were analyzed and compared through the use of lineage mapping and single-cell RNA-sequencing. We observed that although Mist1-expressing non-stem cells do not exhibit stem cell behavior under homeostatic or damage conditions, they can serve as tumor cells-of-origin. These tumors maintain a differentiation hierarchy that is lacking in stem cell-driven tumors. These results suggest that the origin of tumorigenesis influences tumor CSCs and thus tumor characteristics which could be utilized for the development of novel therapies.

Citation Format: Cherie R. Scurrah, Alan J. Simmons, Eunyoung Choi, Robert J. Coffey, James R. Goldenring, Ken S. Lau. Non-stem cell-driven colonic tumors retain an intestinal differentiation hierarchy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4637.

Electron Vorticity Indicative of the Electron Diffusion Region of Magnetic Reconnection

While vorticity defined as the curl of the velocity has been broadly used in fluid and plasma physics, this quantity has been underutilized in space physics due to low time resolution observations. We report Magnetospheric Multiscale (MMS) observations of enhanced electron vorticity in the vicinity of the electron diffusion region of magnetic reconnection. On 11 July 2017 MMS traversed the magnetotail current sheet, observing tailward-to-earthward outflow reversal, current-carrying electron jets in the direction along the electron meandering motion or out-of-plane direction, agyrotropic electron distribution functions, and dissipative signatures. At the edge of the electron jets, the electron vorticity increased with magnitudes greater than the electron gyrofrequency. The out-of-plane velocity shear along distance from the current sheet leads to the enhanced vorticity. This, in turn, contributes to the magnetic field perturbations observed by MMS. These observations indicate that electron vorticity can act as a proxy for delineating the electron diffusion region of magnetic reconnection.

The Relationship Between β-Endorphin and Experimental Pain Sensitivity in Older Adults With Knee Osteoarthritis

Osteoarthritis (OA) is the most common cause of pain in people aged >45 years, and the knee is the most commonly affected joint. There is a growing interest in understanding the biological factors that influence pain among older adults, but few studies have examined the relationship between β-endorphin and experimental pain sensitivity in older adults with knee OA pain. The purpose of this study was to investigate the relationship between resting plasma levels of β-endorphin and experimental pain sensitivity. This study was a secondary analysis of data for 40 adults with knee OA pain in whom quantitative sensory testing was used to measure experimental sensitivity to heat- and mechanically induced pain. The mean age of the sample was 60 years (SD = 9 years), and approximately half were female (53%). Regression analyses indicated that β-endorphin level was negatively related to pressure pain threshold (β = -17.18, p = .02) and positively related to punctate mechanical pain (β = 17.13, p = .04), after controlling for age, gender, and OA severity. We did not find a significant relationship between β-endorphin and heat pain tolerance. The results suggest that higher circulating levels of β-endorphin at rest are associated with increased sensitivity to mechanical pain in older adults with knee OA. These findings add to the literature regarding biological factors associated with pain sensitivity in older adults with chronic pain. Additional studies are needed to identify mediators of the relationship between β-endorphin and pain sensitivity in OA and other musculoskeletal pain conditions.

Cystine/Glutamate Antiporter (xCT) Is Required for Chief Cell Plasticity After Gastric Injury

BACKGROUND & AIMS

Many differentiated epithelial cell types are able to reprogram in response to tissue damage. Although reprogramming represents an important physiological response to injury, the regulation of cellular plasticity is not well understood. Damage to the gastric epithelium initiates reprogramming of zymogenic chief cells into a metaplastic cell lineage known as spasmolytic polypeptide-expressing metaplasia (SPEM). The present study seeks to identify the role of xCT, a cystine/glutamate antiporter, in chief cell reprogramming after gastric injury. We hypothesize that xCT-dependent reactive oxygen species (ROS) detoxification is required for the reprogramming of chief cells into SPEM.

METHODS

Sulfasalazine (an xCT inhibitor) and small interfering RNA knockdown were used to target xCT on metaplastic cells in vitro. Sulfasalazine-treated wild-type mice and xCT knockout mice were analyzed. L635 or DMP-777 treatment was used to chemically induce acute gastric damage. The anti-inflammatory metabolites of sulfasalazine (sulfapyridine and mesalazine) were used as controls. Normal gastric lineages, metaplastic markers, autophagy, proliferation, xCT activity, ROS, and apoptosis were assessed.

RESULTS

xCT was up-regulated early as chief cells transitioned into SPEM. Inhibition of xCT or small interfering RNA knockdown blocked cystine uptake and decreased glutathione production by metaplastic cells and prevented ROS detoxification and proliferation. Moreover, xCT activity was required for chief cell reprogramming into SPEM after gastric injury in vivo. Chief cells from xCT-deficient mice showed decreased autophagy, mucus granule formation and proliferation, as well as increased levels of ROS and apoptosis compared with wild-type mice. On the other hand, the anti-inflammatory metabolites of sulfasalazine did not affect SPEM development.

CONCLUSIONS

The results presented here suggest that maintaining redox balance is crucial for progression through the reprogramming process and that xCT-mediated cystine uptake is required for chief cell plasticity and ROS detoxification.

The heart of an acrobatic bird

The courtship behavior of some species of birds can be energetically demanding, but it is unknown if cardiovascular specializations enable such behaviors. While performing a highly acrobatic courtship dance, heart rate in male golden-collared manakins increases briefly to 1300 beats per minute, among the highest heart rates recorded in any bird or mammal. We hypothesize that male manakins have enhanced cardiovascular capabilities to meet these demands on the heart. Using histological and molecular techniques, we examined manakin heart structure as well as expression of genes involved in Ca²⁺ handling, action potential duration, steroidal signaling and cardiac growth. These measures were also made on the hearts of zebra finches, a similar-sized bird with limited cardiovascular demands. Compared to the zebra finch, the manakin had a significantly thicker left ventricular (LV) muscle (cross-sectional thickness of the free LV wall and septum) with a smaller LV chamber. In addition, compared to zebra finches, manakin hearts had significantly greater gene expression of ryanodine receptors as well as androgen receptors. Testosterone (T) treatment of non-breeding manakins (with low T) increased gene expression of the Ca²⁺ pump SERCA. These observations suggest that hearts of breeding male manakins require specialized Ca²⁺ handling and androgens may facilitate manakin cardiovascular function.

Bayesian analysis of the effect of transcranial direct current stimulation on experimental pain sensitivity in older adults with knee osteoarthritis: randomized sham-controlled pilot clinical study

Purpose

Previous studies have indicated that transcranial direct current stimulation (tDCS) with the anode over the motor cortex and the cathode over the contralateral supraorbital region is effective in reducing clinical pain in patients with chronic pain, but these studies have not focused on experimental pain sensitivity. Therefore, the aim of this study was to examine the effect of tDCS on experimental pain sensitivity in older adults with knee osteoarthritis (OA).

Patients and methods

Forty community-dwelling participants aged 50–70 years with knee OA pain were randomly assigned to receive five daily sessions of 2 mA tDCS for 20 minutes (n = 20) or sham tDCS (n = 20) using a parallel group design. A multimodal quantitative sensory testing battery was completed, including heat pain, pressure pain threshold (PPT), punctate mechanical pain, and conditioned pain modulation (CPM).

Results

The active tDCS group showed greater increases in heat pain thresholds and tolerances, PPTs, and CPM, and reductions in punctate pain. In addition, beneficial changes in experimental pain measures were associated with reductions in clinical pain. Future studies are needed to extend these findings to better understand the underlying mechanisms of tDCS as well as to optimize treatment parameters including number and duration of stimulation sessions.

Conclusion

Our findings demonstrate that tDCS reduces experimental pain sensitivity, and these beneficial changes in experimental pain measures were associated with reductions in clinical pain.

Lrig1+ gastric isthmal progenitor cells restore normal gastric lineage cells during damage recovery in adult mouse stomach

OBJECTIVE

Lrig1 is a marker of proliferative and quiescent stem cells in the skin and intestine. We examined whether Lrig1-expressing cells are long-lived gastric progenitors in gastric glands in the mouse stomach. We also investigated how the Lrig1-expressing progenitor cells contribute to the regeneration of normal gastric mucosa by lineage commitment to parietal cells after acute gastric injury in mice.

DESIGN

We performed lineage labelling using Lrig1-CreERT2/+;R26R-YFP/+ (Lrig1/YFP) or R26R-LacZ/+ (Lrig1/LacZ) mice to examine whether the Lrig1-YFP-marked cells are gastric progenitor cells. We studied whether Lrig1-YFP-marked cells give rise to normal gastric lineage cells in damaged mucosa using Lrig1/YFP mice after treatment with DMP-777 to induce acute injury. We also studied Lrig1-CreERT2/CreERT2 (Lrig1 knockout) mice to examine whether the Lrig1 protein is required for regeneration of gastric corpus mucosa after acute injury.

RESULTS

Lrig1-YFP-marked cells give rise to gastric lineage epithelial cells both in the gastric corpus and antrum, in contrast to published results that Lgr5 only marks progenitor cells within the gastric antrum. Lrig1-YFP-marked cells contribute to replacement of damaged gastric oxyntic glands during the recovery phase after acute oxyntic atrophy in the gastric corpus. Lrig1 null mice recovered normally from acute gastric mucosal injury indicating that Lrig1 protein is not required for lineage differentiation. Lrig1+ isthmal progenitor cells did not contribute to transdifferentiating chief cell lineages after acute oxyntic atrophy.

CONCLUSIONS

Lrig1 marks gastric corpus epithelial progenitor cells capable of repopulating the damaged oxyntic mucosa by differentiating into normal gastric lineage cells in mouse stomach.

Evaluation of Lineage Changes in the Gastric Mucosa Following Infection With Helicobacter pylori and Specified Intestinal Flora in INS-GAS Mice

Gastric adenocarcinoma develops in metaplastic mucosa associated with Helicobacter pylori infection in the stomach. We have sought to evaluate the precise lineage changes in the stomachs of insulin-gastrin (INS-GAS) mice infected with H. pylori and/or intestinal flora (Altered Schaedler's Flora; ASF). Stomachs from groups infected with H. pylori contained progressive spasmolytic polypeptide-expressing metaplasia (SPEM) compared with germ-free and mice infected with ASF alone. The overall phenotype of the H. pylori-infected mice was dominated by Ulex europaeus lectin (UEAI)-positive foveolar hyperplasia that was distinct from GSII/CD44v9-positive SPEM. However, in the mice with H. pylori co-infected with ASF, we identified a subpopulation of UEAI-positive foveolar cells that co-expressed intestinal mucin 4 (MUC4). These regions of foveolar cells were variably positive for CD44v9 as well as TFF3. Interestingly, an intravascular lesion identified in a dual H. pylori/ASF-infected mouse expressed both UEAI and Muc4. Finally, we identified an increase in the number of tuft cells within the mucosa of H. pylori-infected groups. Our findings suggest that H. pylori infection promotes foveolar hyperplasia as well as metaplasia, while co-infection may promote progressive foveolar and metaplastic lesions as well as dysplasia. Grading of gastric lesions in mice as preneoplastic requires multiple immunostaining markers to assign lineage derivation and behavior.

Abstract 4095: Active Kras induced metaplasia progression toward gastric neoplasia is suppressed by MEK inhibition during gastric carcinogenesis

Intestinal type gastric cancer develops within metaplastic mucosal fields and development of gastric neoplasia represents the most prominent example of gastric cancer developing within the morphologic changes of metaplasia. Recent investigations have noted activation of Ras activity in up to 40% of human gastric cancers and suggest. Our recent study has suggested that chief cells might be an origin of gastric cancer using a mouse model, Mist1-CreERT2;LSL-KRas(G12D) mouse (Mist1-Kras).  The Mist1-Kras mice rapidly developed SPEM and IM within 3 months and invasive metaplasia within 4 months following induction of constitutively-active Kras(G12D) expression in the chief cells in the mouse stomach. We also observed regression of metaplasia by targeting downstream mediators of Kras signaling using a MEK inhibitor, Selumetinib. We therefore have now investigated how the progression and proliferation of metaplasia can be controlled. In this study, we have established metaplastic organoid lines (Meta3 and Meta4) from Mist1-Kras mouse stomach mucosa at 3 or 4 months after tamoxifen induction. We examined these organoids to understand the mechanisms of metaplasia progression through MEK inhibition.  Both Meta3 and Meta4 organoids have formed distinguishable glandular structures in 3D cultures and maintained a stable phenotype observed in metaplastic glands in the Mist1-Kras mouse stomachs. The MEK inhibition with Selumetinib in the metaplastic organoids inhibited growth, but promoted differentiation of metaplastic cells toward intestinal absorptive cells with elaboration of an apical brush border. Single cell RNA sequencing data revealed that Meta-4 have distinct characteristics that differ from Meta3. In 3D culture, Meta4 organoids developed more aggressive phenotypes than Meta3 and expressed Cortactin, which has critical roles in cancer cell migration and metastasis. Cortactin localized at the lamellipodia in monolayer culture of Meta4. Meta4 organoids treated with Selumetinib produced significantly fewer colonies in soft agar and resulted in loss of lamellipodia localization of Cortactin. Our results indicate that gastric carcinogenesis can be controlled by a MEK inhibitor, Selumetinib, and support the concept that growth of pre-neoplastic metaplasia and early stage gastric cancer in humans might be controlled with administration of Selumetinib.

Citation Format: Eunyoung Choi, Amy C. Engevik, James R. Goldenring. Active Kras induced metaplasia progression toward gastric neoplasia is suppressed by MEK inhibition during gastric carcinogenesis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4095.

Sexual Maturation, Attitudes towards Sexual Maturity, and Body Esteem in Elementary-School Children

PURPOSE

The purpose of this study is to evaluate sexual maturation, attitudes toward sexual maturity, and body esteem in the sexual development of Korean elementary-school boys and girls.

METHODS

A descriptive cross-sectional study was conducted with 399 fifth and sixth graders (192 boys and 207 girls). The data were analysed with a χ2 test, t-test, and Pearson correlation coefficients.

RESULTS

Among the 207 girls, 70.5% had pubic hair growth, 68.1% had breast development, and 56.0% had a menstrual period. In boys, 59.4% of the 192 subjects experienced the development of external genitalia and 52.6% had pubic hair growth. Sexual maturation was related to grade (boys, t=7.07, p=.008; girls, t=12.76, p < .001), age (t=-2.20, p=.030; t=-4.11, p < .001), height (t=-5.16, p < .001; t=-7.52, p < .001), and weight (t=-2.89, p=.004; t=-5.19, p < .001) in both boys and girls. Girls were more likely to have sexual maturity than boys (χ2=22.29, p < .001). Boys showed more positive attitudes toward sexual maturity (t=2.10, p=.036) and higher body esteem (t=2.12, p=.035) than girls.

CONCLUSION

This study shows that sexual maturation, attitude toward sexual maturity, and body esteem in sexual development differ between boys and girls. The findings indicate that it is necessary to develop a tailored sex-education program according to the sex of elementary-school children.

A signalling cascade of IL-33 to IL-13 regulates metaplasia in the mouse stomach

OBJECTIVE

Alternatively activated macrophages (M2) are associated with the progression of spasmolytic polypeptide-expressing metaplasia (SPEM) in the stomach. However, the precise mechanism(s) and critical mediators that induce SPEM are unknown.

DESIGN

To determine candidate genes important in these processes, macrophages from the stomach corpus of mice with SPEM (DMP-777-treated) or advanced SPEM (L635-treated) were isolated and RNA sequenced. Effects on metaplasia development after acute parietal cell loss induced by L635 were evaluated in interleukin (IL)-33, IL-33 receptor (ST2) and IL-13 knockout (KO) mice.

RESULTS

Profiling of metaplasia-associated macrophages in the stomach identified an M2a-polarised macrophage population. Expression of IL-33 was significantly upregulated in macrophages associated with advanced SPEM. L635 induced metaplasia in the stomachs of wild-type mice, but not in the stomachs of IL-33 and ST2 KO mice. While IL-5 and IL-9 were not required for metaplasia induction, IL-13 KO mice did not develop metaplasia in response to L635. Administration of IL-13 to ST2 KO mice re-established the induction of metaplasia following acute parietal cell loss.

CONCLUSIONS

Metaplasia induction and macrophage polarisation after parietal cell loss is coordinated through a cytokine signalling network of IL-33 and IL-13, linking a combined response to injury by both intrinsic mucosal mechanisms and infiltrating M2 macrophages.