Circulating miRNAs (cirmiRNAs) can be packaged into the exosomes, participating in intercellular communication, which affects the malignant progression and therapy resistance of triple‐negative breast cancer (TNBC). Currently, immune checkpoint inhibitors that regulate T‐cell function, especially antibodies against programmed cell death 1 (PD‐1) or its ligand PD‐L1, are emerging as new promising therapy for TNBC patients. However, only very limited patients showed complete or partial response to anti‐PD‐1 treatment. Dysfunction of CD8⁺ T cells is one of the key reasons for the immune escape of TNBC. The regulation of exosome‐derived cirmiRNAs on CD8⁺ T cells in TNBC deserves more investigation. Here, the cirmiR‐20a‐5p level was significantly upregulated in the plasma of TNBC patients and culture supernatant of TNBC cells. High abundance of cirmiR‐20a‐5p was correlated with a worse prognosis of TNBC. cirmiR‐20a‐5p was secreted in the form of exosomes by TNBC cells. Exosomal cirmiR‐20a‐5p was internalized into CD8⁺ T cells and resulted into the dysfunction of CD8⁺ T. A mechanism study uncovered that cirmiR‐20a‐5p targeted the nuclear protein ataxia‐telangiectasia (NPAT) and decreased NPAT expression in CD8⁺ T cells. An in vivo xenograft mouse model showed that cirmiR‐20a‐5p conferred TNBC to anti‐PD‐1 treatment resistance. Collectively, these findings indicated that cirmiR‐20a‐5p released by TNBC cells via exosome promotes cancer cell growth and leads to the immunosuppression by inducing CD8⁺ T cell dysfunction. This study suggests that targeting cirmiR‐20a‐5p might be a novel strategy for overcoming the resistance of TNBC to anti‐PD‐1 immunotherapy.

Background: Perineural invasion (PNI) is common in a variety of solid tumors and has been identified as an important pathway promoting tumor local invasion and distant metastasis. Its presence is usually associated with increased aggressiveness, malignant biology, and a worse patient prognosis. However, its specific role and regulatory mechanisms in colorectal cancer (CRC) remain unclear.Methods: In this study, we integrated 20 CRC single-cell transcriptome datasets, which contained 575,768 high-quality cells, and used the Scissor algorithm to map PNI phenotypes in TCGA bulk samples to the single-cell level. Nine cancer-associated fibroblast (CAF) subpopulations were identified and functionally annotated. We evaluated the clinical relevance of CAF subsets in TCGA and three independent cohorts (silu_2022, GSE39582, and GSE17536) using BayesPrism-based deconvolution. We analyzed transcriptional regulatory networks using pySCENIC and validated PRRX2 function by in vitro experiments. Immune infiltration characteristics were quantified using the ssGSEA score, and the association between the PRRX2 score and immune checkpoint inhibitor efficacy was analyzed in conjunction with two immunotherapy cohorts. In addition, we performed a drug sensitivity analysis based on the GDSC pharmacogenomics database to screen potential therapeutic agents.Results: In this study, we systematically revealed the characteristics of the perineural invasion-associated fibroblast subsets and their regulatory mechanisms. In PNI-positive tumors, the proportion of fibroblasts was significantly increased, with the enrichment of MMP2+ myofibroblastic cancer-associated fibroblasts (myCAFs), and facilitated perineural infiltration through extracellular matrix remodeling. Further analysis revealed that PRRX2 was a core regulator of MMP2+myCAFs, promoting perineural invasion through the activation of TGF-β signaling pathways. PRRX2 knockdown significantly inhibited fibroblast proliferation, clonogenic formation, and invasive migration capacity, and it reduced TGFB1 and NGF expressions. The clinical cohort validation demonstrated a significant correlation between the PRRX2-score and advanced tumor stage, along with vascular and lympho-vascular invasion (LVI). Furthermore, patients with high PRRX2 scores had a significantly worse prognosis. In addition, patients with high PRRX2 scores responded poorly to immune checkpoint inhibitors but may be sensitive to targeted agents or antibody-coupled drugs, which may serve as potential targets for combination therapy.Conclusion: This analysis established PRRX2-driven MMP2+myCAFs as pivotal mediators of CRC perineural invasion through TGF-β/ECM remodeling. The PRRX2 score serves as a biomarker for prognosis prediction and immunotherapy outcome.

Purpose: This study aimed to explore the dysregulation of miR-145-5p in gastric cancer (GC) and its effects on the proliferation and cell cycle of GC cells, exploring the potential regulatory mechanism of miR-145-5p in GC.Methods: In this study, the TCGA database combined with Microarray was used to detect differentially expressed microRNA (miRNA) in GC tissues and cells. Quantitative real-time (qRT)-PCR was used to further verify the expression of miR-145-5p in GC cells and the 41 pairs of GC tissues and adjacent tissues. A retrospective analysis was conducted on the correlation between miR-145-5p and the clinicopathological characteristics of patients with GC. The proliferation ability and cell cycle of AGS and MKN28 were detected by CCK-8, Edu and flow cytometry. The downstream target genes of miR-145-5p were screened by bioinformatics and further verified by the dual-luciferase reporter assay. Immunohistochemistry was used to detect the expression of SMAD5 in GC tissues. Western blot was used to detect cell cycle-related proteins that were regulated by siRNA SMAD5.Results: The expression of miR-145-5p was lower in GC tissues and cells compared with adjacent tissues and GES-1, and was related to the poor prognosis of patients with GC. Overexpression of miR-145-5p inhibited the proliferation of GC cells and blocked the cell cycle from G1 phase to S phase. MiR-145-5p targeted SMAD5 to inhibit the proliferation, and arrested the G1/S phase transition of GC cells. Mechanistically, SMAD5 siRNA significantly reduced CCND1 protein expression, Bioinformatics databases predicted that cyclin D1 was the transcription target gene of SMAD5. Moreover, the re-expression of cyclin D1 partially reversed the cell cycle arrest that was induced by SMAD5 depletion in GC cells.Conclusion: Taken together, these findings reveal a novel role of the miR-145-5p/SMAD5/cyclin D1 axis in modulating cell cycle progression and cell proliferation in GC, which may provide a prognostic biomarker for GC treatment.

Background: Genetic mutations are quite common in non-small cell lung cancer (NSCLC), however, their prognostic value remains controversial. Methods: This study explored the mutational landscape of tumor samples from patients with advanced NSCLC by next-generation sequencing (NGS). A total of 101 NSCLC patients in stage III or IV receiving first-line treatment were included. Results: TP53 mutation was the most frequent genetic alteration in NSCLC tumors (68%), followed by EGFR (49%), CDKN2A (12%), LRP1B (9%), and FAT3 (9%) mutations. Among 85 patients with stage IV NSCLC, first-line targeted therapy remarkably prolonged progression-free survival (PFS) of patients compared with first-line chemotherapy (p = 0.0028). Among 65 patients with stage IV NSCLC whose tumors harbored EGFR, ALK, ROS, or BRAF mutations, first-line targeted therapy substantially prolonged the PFS of patients (p = 0.0027). In patients with TP53 mutations who received first-line targeted therapy or chemotherapy, missense mutation was the most common mutation type (36/78), and exon 5 represented the most common mutated site (16/78). Conclusions: TP53 mutation in exon 5 could independently predict poor PFS of patients with stage IV NSCLC after the first- line treatment. Moreover, mutations in TP53 exon 5 and LRP1B were associated with shorter PFS of such patients whether after first-line chemotherapy or targeted therapy, respectively. Thus, these patients should be given immunotherapy or immunochemotherapy.