Research Report: The Regulatory Role of ROR2 in Pancreatic Cancer Cell Plasticity

Background Introduction

Pancreatic ductal adenocarcinoma (PDAC) is a deadly disease with most patients lacking the possibility of a cure. This is partly due to the difficulty in early detection. One of the characteristics of PDAC is its extensive tumor cell heterogeneity, which is reflected in the variations between “classical” and “basal-like” molecular subtypes, as well as the deep mechanisms of treatment resistance resulting from cellular plasticity. This plasticity is prevalent throughout the progression of PDAC, including the transformation of normal cells into precancerous lesions and malignant tumors, accompanied by the acquisition of different cellular identities.

Studies have shown that different ductal and acinar cells can generate PDAC in pancreatic cancer mouse models. Acinar cells are more prone to transformation in mice. Inflammation or carcinogenic expression of KRASG12D can induce the transformation of acinar cells into duct-like precursor cells, known as acinar-ductal metaplasia (ADM). Metaplastic ductal cells are characterized by the upregulation of gene expression defining normal ductal cells (such as KRT19 and SOX9). Most adult acinar cells exhibit resistance to KRASG12D transformation; however, the combination of KRAS expression with the loss of transcription factors HNF1A, NR5A2, MIST1, PTF1A, and PDX1 significantly accelerates the transformation.

Source of the Paper

This research was conducted by Dr. Howard C. Crawford’s team at the Henry Ford Health System, including researchers Simone Benitz, Alec Steep, Malak M. Nasser, and many others. Co-authors also include scientists from the University of Chicago, Cold Spring Harbor Laboratory, Technical University of Munich, and other research institutions. The paper was published in the July 2024 issue of Cancer Discovery.

Research Details

The study found that the transcription factor PDX1 maintains the differentiation of normal acinar cells and inhibits the identity of gastric metaplastic cells in both mice and humans. In pancreatic tumor mouse models, the cell identity transition triggered by the loss of ROR2 predominantly persisted into the PDAC progression stage. In both mouse and human pancreatic cancer, the persistent activity of ROR2 significantly counteracts the gastric zymogen cell identity, leading to epithelial-mesenchymal transition (EMT), resistance to KRAS inhibitors, and sensitivity to AKT inhibition.

Research Procedure

The research was divided into several major steps, detailed as follows:

1. SnATAC-seq Tracking of Cell Identity Changes

By rapidly freezing mouse pancreas tissue and employing single-nucleus ATAC-seq (snATAC-seq) technology, a variety of cell types were identified. The chromatin accessibility markers generated were used to determine cell identities. The analysis showed that PTF1AERT-guided pancreatic acinar transformation to duct-like cells manifests as a loss of acinar marker AMY1 and ductal marker KRT19 expression, along with surrounding stromal responses.

2. Role of ROR2 in Acinar Cell Transformation

Through the integrated analysis of snATAC-seq and RNA-seq, significant changes in genes such as ROR2 were discovered. Further analysis confirmed the expression of ROR2 in various gastric cell populations, including endocrine cells and neck cells. Moreover, relevant expression was also found in pancreatic metaplastic lesions.

3. Experimental Design and Data Analysis

In the scientific models, researchers used ptf1aert;kraslsl-g12d and ptf1aert;kraslsl-g12d;pdx1flox/flox mouse models, treating with tamoxifen to observe the complete transformation of acinar cells into duct-like cells, accompanied by significant fibroinflammatory responses. These changes were validated in the chromatin accessibility dimension using snATAC-seq technology and further corroborated by plastid staining techniques.

4. Exploration of ROR2 Regulation

Scientists confirmed through a series of experiments that ROR2 is not only expressed in gastric and wound healing cells but also plays a crucial role in the malignant transformation process. By creating ptf1aert;kraslsl-g12d;ror2f/f mouse models, the research showed that the loss of ROR2 promotes tissue transformation and fibrosis, cell identity conversion to gastric zymogen cells, significantly increasing the risk of PDAC development.

Main Research Results

1. Data Analysis Results: Through high-quality snATAC-seq, the study found changes in gene expression, particularly the key role of ROR2 in pro-carcinogenic transformation and cell identity regulation.
2. Data Explanation: By comparing cell atlases of different mouse models, the critical impact of ROR2 expression on cell identity and cancer progression was determined.

Conclusion and Significance

The study identifies that ROR2 is an important regulator of cell identity, influencing pancreatic precancerous lesions and the cancerization process. ROR2 significantly affects the conversion of gastric cell identity in PDX1-deficient mouse acinar cells and exhibits an aggressive cancerous phenotype and resistance to KRAS inhibitors during the PDAC progression stage. Conversely, inhibiting ROR2 increases sensitivity to AKT inhibitors. In summary, targeting ROR2 for therapy may enhance the effect of novel targeted therapies, offering new insights for pancreatic cancer treatment.

Research Highlights

1. Discovery of New Markers: Identifies ROR2 for the first time as an important regulator of pancreatic precancerous lesions and pancreatic cancer.
2. Mechanism Elucidation: Deeply reveals the dual role of ROR2 in cell identity transition, providing new insights into the formation and progression of pancreatic cancer.
3. Therapeutic Potential: By regulating ROR2, the study enhances the treatment sensitivity of pancreatic cancer to KRAS and AKT inhibitors, providing a new target for precise treatment of pancreatic cancer.

Summary

This paper is highly significant in the study of cellular transformation and pancreatic cancer. By deeply exploring the function of ROR2 and its regulation of cell identities, it offers new avenues and potential targeted methods for treating pancreatic cancer. This discovery is expected to play a critical role in future cancer treatments, bringing revolutionary breakthroughs to sugar research.