Kaneda, M. | Search bioRxiv

bioRxiv2026

Stepwise bladder carcinogenesis reveals transcriptional reprogramming involving MMP1 and COL7A1

Bladder cancer develops through multistep molecular alterations, yet the events underlying tumor initiation and progression remain poorly understood. Here, we reconstructed stepwise bladder carcinogenesis using canine bladder organoids combined with chemical carcinogenesis and serial xenotransplantation. Carcinogen-exposed normal organoids generated benign tumors that subsequently progressed to invasive carcinomas. Despite a low tumor mutational burden and limited acquisition of cancer-associated mutations, malignant progression was accompanied by extensive transcriptional reprogramming, including enrichment of epithelial-to-mesenchymal transition programs. COL7A1 and MMP1 were progressively upregulated during progression, and knockdown of either gene suppressed organoid proliferation and invasion. These functional dependencies were reproduced in independently established spontaneous canine bladder cancer organoids, where silencing of either gene also reduced xenograft growth and mitosis-related gene programs. MMP1 knockdown decreased COL7A1 expression, suggesting a potential regulatory relationship. MMP1 was also elevated in basal/squamous human bladder cancers, and its depletion suppressed human bladder cancer cell proliferation. These findings identify transcriptional reprogramming and MMP1/COL7A1 dependencies as prominent features of malignant progression.

cancer biology↗

bioRxiv2025

Early transcriptional divergence underlies cell fate bias in bovine embryos

Developmental plasticity, or the ability of early embryonic cells to contribute to multiple lineages, is traditionally considered equal among sister blastomeres during early cleavage. However, divergence may occur earlier than expected. We performed single-cell RNA sequencing of bovine embryos from the 2- to 8-cell stages to examine transcriptional asymmetry. While gene expression was uniform at the 2-cell stage, variability increased at the 4-cell stage and became pronounced by the 8-cell stage. At this stage, blastomeres showed heterogeneity in MAPK pathway genes (e.g., RAC1, MAPK14) and the trophectoderm marker CDX2. These differences were associated with blastomere size; larger blastomeres more frequently initiated cavity formation, a functional marker of trophectoderm fate. Our findings suggest that both molecular and physical asymmetries contribute to early lineage bias, and that developmental plasticity may be lost in an asynchronous, cell-specific manner before visible morphological events such as compaction.

developmental biology↗