Manipulation of DNA Repair Proficiency in Mouse Models of Colorectal Cancer

Qingre Huayu Jianpi prescription alleviates the inflammatory transformation of colitis-associated colorectal cancer by inhibiting the IL-17RA/ACT1/NF-κB axis

ETHNOPHARMACOLOGICAL RELEVANCE

Inflammation-to-cancer transformation is critical for the progression of ulcerative colitis to colitis-associated colorectal cancer (CAC).

AIM OF THE STUDY

To explore the role and potential mechanisms of Qingre Huayu Jianpi prescription (QHJ) treatment in the development of CAC.

MATERIALS AND METHODS

Combined network pharmacology and transcriptome analyses were used to investigate QHJ-associated targets and pathways in the context of CAC. Using clinical data and a murine CAC model, we examined QHJ effects on pathological morphology, inflammatory factors, and key target pathways.

RESULTS

Network pharmacology analysis identified the interleukin 17 receptor A (IL-17RA)/ACT1/nuclear factor kappa B (NF-κB) axis as critical in the inflammation-to-CAC transformation and for QHJ effects in CAC. Western blot and multiplex immunofluorescence analyses revealed significant upregulation of the IL-17RA/ACT1/NF-κB axis along with matrix metalloproteinase (MMP)7, MMP9, and chemokine ligand 2 (CCL2) in human tumor tissues. QHJ significantly ameliorated CAC-related symptoms in mice in vivo by downregulating the IL-17RA/ACT1/NF-κB axis. This reduced the number of colorectal adenomas, increased colorectal length, and improved the structure of colonic mucosal glands. Additionally, QHJ inhibited the expression of pro-inflammatory factors and decreased the levels of MMP7, MMP9, and CCL2, ultimately suppressing the inflammation-to-cancer transformation.

CONCLUSION

QHJ exhibited significant therapeutic effects on CAC in mice, likely due to its inhibitory action on the IL-17RA/ACT1/NF-κB axis. This study lays the foundation for research into the pathogenesis of CAC and the clinical application of QHJ.

14-3-3σ Functions as an Intestinal Tumor Suppressor

Although the 14-3-3σ gene was initially identified as a p53 target gene in colorectal cancer cells, its potential role in intestinal tumorigenesis has remained unknown. Here we determined that 14-3-3σ expression is significantly downregulated in primary human colorectal cancer when compared with adjacent normal colonic tissue in patient samples. Downregulation of 14-3-3σ in primary colorectal cancers was significantly associated with p53 mutation, increasing tumor stage, distant metastasis, and poor patient survival. Poor survival was more significantly associated with decreased 14-3-3σ expression in p53 wild-type than in p53-mutant colorectal cancers. 14-3-3σ expression was detected in enterocytes of the transit amplifying zone and gradually increased towards the apical villi in the small intestinal epithelium. In small and large intestinal epithelia and adenomas, 14-3-3σ expression was upregulated in differentiated areas. Deletion of 14-3-3σ in Apc^Min mice increased the number and size of adenomas in the small intestine and colon, shortening the median survival by 64 days. 14-3-3σ-deficient adenomas displayed increased proliferation and decreased apoptosis, as well as increased dysplasia. In adenomas, loss of 14-3-3σ promoted acquisition of a mesenchymal-like gene expression signature, which was also found in colorectal cancers from patients with poor relapse-free survival. The transcriptional programs controlled by the 14-3-3σ-interacting factors SNAIL, c-JUN, YAP1, and FOXO1 were activated by deletion of 14-3-3σ, potentially contributing to the enhanced tumor formation and growth. Taken together, these results provide genetic evidence of a tumor-suppressor function of 14-3-3σ in the intestine. SIGNIFICANCE: Downregulation of 14-3-3σ in colorectal cancer is associated with metastasis and poor survival of patients, and its inactivation in a murine tumor model drives intestinal tumor formation and epithelial-mesenchymal transition.

Investigating Tumor Heterogeneity in Mouse Models

Cancer arises from a single cell through a series of acquired mutations and epigenetic alterations. Tumors gradually develop into a complex tissue comprised of phenotypically heterogeneous cancer cell populations, as well as noncancer cells that make up the tumor microenvironment. The phenotype, or state, of each cancer and stromal cell is influenced by a plethora of cell-intrinsic and cell-extrinsic factors. The diversity of these cellular states promotes tumor progression, enables metastasis, and poses a challenge for effective cancer treatments. Thus, the identification of strategies for the therapeutic manipulation of tumor heterogeneity would have significant clinical implications. A major barrier in the field is the difficulty in functionally investigating heterogeneity in tumors in cancer patients. Here we review how mouse models of human cancer can be leveraged to interrogate tumor heterogeneity and to help design better therapeutic strategies.

The Clinical Impact of the Genomic Landscape of Mismatch Repair-Deficient Cancers

The mismatch repair (MMR) system which detects and corrects base mismatches and insertions and deletions that occur during DNA synthesis is deregulated in approximately 20% of human cancers. MMR-deficient tumors have peculiar properties, including early-onset metastatic potential but generally favorable prognosis, and remarkable response to immune therapy. The functional basis of these atypical clinical features has recently started to be elucidated. Here, we discuss how the biological and clinical features of MMR-deficient tumors might be traced back to their ability to continuously produce new somatic mutations, leading to increased levels of neoantigens, which in turn stimulate immune surveillance. SIGNIFICANCE: Tumors carrying defects in DNA MMR accumulate high levels of mutations, a feature linked to rapid tumor progression and acquisition of drug resistance but also favorable prognosis and response to immune-checkpoint blockade. We discuss how the genomic landscape of MMR-deficient tumors affects their biological and clinical behaviors.