Ectopic excitability in pulmonary veins (PVs) is the major cause of atrial fibrillation. We previously reported that the inositol trisphosphate receptor in rat PV cardiomyocytes cooperates with the Na⁺-Ca²⁺ exchanger to provoke ectopic automaticity in response to norepinephrine. Here, we focused on adenylyl cyclase (AC) as another effector of norepinephrine stimulation. RT-PCR, immunohistochemistry, and Western blotting revealed that the abundant expression of Ca²⁺-stimulable AC3 was restricted to the supraventricular area, including the PVs. All the other AC isotypes hardly displayed any region-specific expressions. Immunostaining of isolated cardiomyocytes showed an enriched expression of AC3 along the t-tubules in PV myocytes. The cAMP-dependent response of L-type Ca²⁺ currents in the PV and LA cells is strengthened by the 0.1 mM intracellular Ca²⁺ condition, unlike in the ventricular cells. The norepinephrine-induced automaticity of PV cardiomyocytes was reversibly suppressed by 100 µM SQ22536, an adenine-like AC inhibitor. These findings suggest that the specific expression of AC3 along t-tubules may contribute to arrhythmogenic automaticity in rat PV cardiomyocytes.

Background: Jawbone invasion is a common and prognostically unfavorable feature of oral squamous cell carcinoma (OSCC). Although cancer-associated fibroblasts (CAFs) are recognized for their role in tumor progression, their spatial dynamics at the tumor–bone interface remain poorly understood. Methods: We analyzed 14 OSCC specimens with confirmed jawbone invasion using histopathological and immunohistochemical techniques. Digital pathology combined with AI-assisted image analysis was employed to quantify and visualize the spatial distribution of OSCC cells (RANKL-positive), CAFs (α-SMA and FAP-positive), and osteoclasts (cathepsin K-positive) within defined regions of interest at the tumor–bone invasive front. Results: A consistent laminar stromal region enriched in CAFs was observed between the tumor nests and jawbone. CAFs were spatially clustered near OSCC cells and osteoclasts, with 81% and 74% residing within 50 μm, respectively. On average, 11.4 CAFs were present per OSCC cell and 23.2 per osteoclast. These spatial proximities were largely preserved irrespective of stromal thickness, suggesting active bidirectional cellular interactions. Conclusions: Our findings demonstrate that CAFs are strategically positioned to facilitate intercellular signaling between tumor cells and osteoclasts, potentially coordinating OSCC proliferation and bone resorption. This study highlights the utility of AI-assisted spatial histology in unraveling tumor microenvironmental dynamics and proposes CAFs as potential therapeutic targets in OSCC-induced osteolytic invasion.

Despite advances in multidisciplinary treatment, recurrence remains a major clinical challenge in refractory cancers. Many patients have residual tumor after neoadjuvant chemotherapy (NAC), and clinical outcomes among patients without a pathological complete response (non-pCR) are heterogeneous. The spatial relationships between residual tumor cells and surrounding stromal cells may provide information for further prognostic stratification. In this review, we discuss histology-based spatial analysis (HSA) of surgical specimens, with particular attention to pancreatic ductal adenocarcinoma. We describe four steps that connect existing biological, histological, and clinical findings. First, intercellular distances and local cell numbers are compared to identify candidate partner cells. Second, functional and molecular studies examine their interactions with tumor cells, including effects on survival and drug resistance. Third, HSA of immunostained patient specimens measures the number, size, and localization of foci containing cell relationships supported by these studies. Fourth, these measurements are evaluated in relation to recurrence and survival, alongside established clinicopathological factors. This approach uses archival surgical specimens to connect biological findings with patient outcomes. Its value for prognostic stratification after NAC requires validation in large clinical cohorts.

Background/Objectives: Meningiomas frequently involve the adjacent skull bone. The bone tumor microenvironment (TME) represents a unique niche in bone-invasive tumors and bone metastases, and can promote tumor progression through tumor–stromal interactions. We hypothesized that the bone TME may contribute to tumor cell transcriptional changes and tumor growth in meningioma. Methods: Human malignant meningioma cell lines, IOMM-Lee and HKBMM, were implanted over the calvarial bone (bone TME) and into the dorsal skin (non-bone TME) of BALB/c-nu/nu mice. Tumors from the IOMM-Lee model underwent bulk RNA sequencing with computational separation of human- and mouse-derived reads, enabling ligand–target interaction analysis of stromal cell-to-tumor cell signaling. Differential gene expression analysis, enrichment analysis, ligand–target interaction analysis, multiplex immunofluorescence, and immunohistochemistry were performed. Results: Tumor volume was significantly greater in the bone TME than in the non-bone TME in both models, whereas the Ki-67 labeling index was significantly reduced. Transcriptomic analysis revealed distinct tumor cell transcriptional states in the bone TME, characterized by upregulation of inflammation-related genes and enrichment of inflammatory signaling pathways, including interferon responses and NF-κB signaling. Ligand–target interaction analysis of stromal cell-to-tumor cell signaling identified stromal IL1B as a candidate regulator of inflammatory transcriptional programs in tumor cells. F4/80-positive macrophages expressed IL-1β, and tumor cells were positive for phospho-IKKα/β and phospho-IκBα in the bone TME. Conclusions: Tumor–stromal interactions potentially involving macrophage-derived IL-1β may be associated with inflammatory transcriptional programs in meningioma cells and with meningioma enlargement in the bone TME. These interactions may be therapeutically relevant in meningioma with bone involvement.