Transcriptional profiling of human cartilage endplate cells identifies novel genes and cell clusters underlying degenerated and non-degenerated phenotypes

BACKGROUND

Low back pain is a leading cause of disability worldwide and is frequently attributed to intervertebral disc (IVD) degeneration. Though the contributions of the adjacent cartilage endplates (CEP) to IVD degeneration are well documented, the phenotype and functions of the resident CEP cells are critically understudied. To better characterize CEP cell phenotype and possible mechanisms of CEP degeneration, bulk and single-cell RNA sequencing of non-degenerated and degenerated CEP cells were performed.

METHODS

Human lumbar CEP cells from degenerated (Thompson grade ≥ 4) and non-degenerated (Thompson grade ≤ 2) discs were expanded for bulk (N=4 non-degenerated, N=4 degenerated) and single-cell (N=1 non-degenerated, N=1 degenerated) RNA sequencing. Genes identified from bulk RNA sequencing were categorized by function and their expression in non-degenerated and degenerated CEP cells were compared. A PubMed literature review was also performed to determine which genes were previously identified and studied in the CEP, IVD, and other cartilaginous tissues. For single-cell RNA sequencing, different cell clusters were resolved using unsupervised clustering and functional annotation. Differential gene expression analysis and Gene Ontology, respectively, were used to compare gene expression and functional enrichment between cell clusters, as well as between non-degenerated and degenerated CEP samples.

RESULTS

Bulk RNA sequencing revealed 38 genes were significantly upregulated and 15 genes were significantly downregulated in degenerated CEP cells relative to non-degenerated cells (|fold change| ≥ 1.5). Of these, only 2 genes were previously studied in CEP cells, and 31 were previously studied in the IVD and other cartilaginous tissues. Single-cell RNA sequencing revealed 11 unique cell clusters, including multiple chondrocyte and progenitor subpopulations with distinct gene expression and functional profiles. Analysis of genes in the bulk RNA sequencing dataset showed that progenitor cell clusters from both samples were enriched in "non-degenerated" genes but not "degenerated" genes. For both bulk- and single-cell analyses, gene expression and pathway enrichment analyses highlighted several pathways that may regulate CEP degeneration, including transcriptional regulation, translational regulation, intracellular transport, and mitochondrial dysfunction.

CONCLUSIONS

This thorough analysis using RNA sequencing methods highlighted numerous differences between non-degenerated and degenerated CEP cells, the phenotypic heterogeneity of CEP cells, and several pathways of interest that may be relevant in CEP degeneration.

Silent Conversations: Goals of Care and End-of-Life Quality in Relapsed High-Risk Leukemia

Background

Advanced practice providers (APPs) affect high-quality health care through leadership, evidence-based practice implementation, and quality improvement projects. When planning solutions to clinical problems, leadership must solicit APP input to promote success. Hematology patients are more likely to receive poor-quality end-of-life (EOL) care than those with solid tumors. Regardless of disease, aggressive EOL care is increasing despite evidence that it is often inconsistent with patients' goals of care (GOC). Data regarding this phenomenon in hematology specifically is lacking. The distorted association of "end of life" with "goals of care" has "silenced" crucial goals discussions in patients with relapsed or refractory high-risk leukemia, which raises concerns for the provision of care that is inconsistent with patients' values and preferences. Hematologists may possess certain traits and distinct barriers leading to what one might call an aversion to GOC discussions in the inpatient setting.

Aims

(1) Quantify hematologists' rate of participation in a GOC pathway initiative during two separate months. (2) Explore the hematologists' definition of and barriers to having GOC discussions.

Design

This is a mixed-methods, explanatory sequential design (follow-up explanations variant).

Sample

Quantitative: Hematology inpatient admissions during two nonconsecutive months in 2021. Qualitative: Eighteen leukemia hematologists from one dedicated cancer center.

Results

During the 2 months, an average of 36% of admissions met the criteria for GOC pathway initiation, 19% of those had an appropriate initiation order, and < 1% had a properly documented and billed GOC discussion. Nine hematologists responded to a SurveyMonkey poll with two questions. All nine included clinical situation and communication in their definition of GOC discussions. Time limitations and prognostic uncertainty were the two most reported barriers.

Discussion

The findings demonstrate that the apprehension of hematologists to have GOC conversations is similarly seen in the APPs' reluctance to initiate a pathway intended to lead to GOC conversations. The percentage of eligible inpatient admissions meeting the specified criteria was similar between the 2 months; however, the number of appropriate referrals and documented or billed GOC discussions was higher in the earlier month, demonstrating temporal decline. Further research inquiry is needed to explore causation of this phenomenon.

Abstract B008: Lipocalin-2 expression modulates ferroptosis in pancreatic ductal adenocarcinoma

Background: Pancreatic Ductal Adenocarcinoma (PDAC) is the third leading cause of cancer-related death in the US. Lipocalin 2 (LCN2) is upregulated in PDAC patients and promotes inflammation and tumor growth. LCN2 regulates iron levels, which are dysregulated in tumors as cancer cells uptake increased iron to support growth. High iron levels can lead to ferroptosis, an iron-catalyzed form of cell death that relies on the oxidation of poly-unsaturated fatty acids (PUFAs). Ferroptosis is usually inhibited in cancer to prevent cell death and promote tumor growth. Therefore, LCN2 expression might influence ferroptosis outcomes in PDAC. Objective: To determine whether LCN2 inhibits ferroptosis and whether modulating LCN2 levels and other targets can be leveraged as treatments to induce ferroptosis in PDAC. Methods: Lcn2 expression was deleted via CRISPR in a mouse PDAC cell line (mKPC) to generate control Lcn2+/+ and Lcn2-/- mKPC cells. Gene expression changes were analyzed with RNA sequencing. Human and mouse PDAC cells were treated with a ferroptosis inducer, LCN2 blockade, and various PUFAs. Treatment effects on cell proliferation and lipid peroxidation were measured via 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl) -2-(4-sulfophenyl)-2H-tetrazolium) (MTS) assay and BODIPY 581/591 C11 staining respectively. Gene expression of ferroptosis markers (SLC7A11, GPX4, and SLC11A2) and LCN2 were measured via RT-qPCR. Results: Deletion of Lcn2 in mKPC cells significantly decreased the expression of genes involved in ferroptosis-inhibiting antioxidant synthesis. Ferroptosis induction upregulated Lcn2 expression in PDAC cells and decreased the viability of mKPC Lcn2-/- and human PDAC cells, but not mKPC Lcn2+/+ or human pancreatic duct epithelial cells. LCN2 blockade treatment to PDAC cells modulated the expression SLC7A11, GPX4, and SLC11A2, key enablers and inhibitors of the ferroptosis antioxidant pathway. Conclusions: Ferroptosis decreases proliferation of PDAC cells, which might be mediated by LCN2 expression. LCN2 modulation has potential to induce ferroptosis and delay PDAC growth. Future studies will determine whether a combination approach with LCN2 modulation could induce ferroptosis in PDAC. Acknowledgments: This research is supported by the OSU Pelotonia Fellowship Program and the NCI R01CA223204.

Citation Format: Valentina Pita Grisanti, Andrew W. Dangel, Maciej Pietrzak, Amy Hite, Zobeida Cruz-Monserrate. Lipocalin-2 expression modulates ferroptosis in pancreatic ductal adenocarcinoma [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer; 2022 Sep 13-16; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2022;82(22 Suppl):Abstract nr B008.

Innovative Assessments for Retention of Sexual Assault Nurse Examiners

The Southeast Kansas (SEK) comprehensive rural Sexual Assault Nurse Examiners (SANE) program was developed as part of an effort to increase the availability of SANE services nationwide. The primary goal of the program is to provide education to assist with training and certification of registered nurses and advanced practice registered nurses in SEK to conduct sexual assault forensic examinations and become certified. This will provide better physical and mental health care for survivors and better evidence collection and higher prosecution rates in a rural, medically underserved area. The project established a rural academic-practice-community partnership to provide longitudinal immersive SANE clinical training. The success of the project in SEK will be impacted by the retention of SANEs; therefore, the integration of the Professional Quality of Life (ProQOL) self-assessment was seen as an important component of the grant implementation. ProQOL determines compassion satisfaction, burnout, and secondary traumatic stress. The data collected from SANEs on their self-assessments with the ProQOL lead to early identification of SANEs experiencing negative effects of forensic nursing and the ability to intervene for decreased attrition.