👤 Koichiro Kuwahara

Pancreatic ductal adenocarcinomas (PDACs) with wild-type KRAS constitute a small fraction of PDACs, and these tumors were recently shown to harbor frequent actionable oncogenic mutations and fusions. However, the clinicopathological features of KRAS wild-type PDAC have not been well studied. Additionally, precancerous lesions occurring in patients with KRAS wild-type PDACs have rarely been characterized. Here, we investigated the clinicopathological characteristics and outcomes of 75 patients with KRAS wild-type PDAC. Molecular analyses were performed in 40 patients using targeted DNA and whole-exome sequencing and targeted RNA sequencing. We demonstrated that patients with metastatic PDAC with wild-type KRAS were younger (median 59.5 years) than those with mutated KRAS (median 67 years, p < 0.000055). The wild-type KRAS status was not a significant prognostic factor for metastatic disease. Molecularly, genes in the RAS pathway are frequently mutated or rearranged (46%, 16/35), including mutations in BRAF, NRAS, HRAS, EGFR, MAP2K1, FGFR1, FGFR3 and ERBB4 and fusions of FGFR2 (FGFR2::CCDC147, FGFR2::CAT, FGFR2::TXLNA), ALK (STRN::ALK, EML4::ALK), and BRAF (TRIP11::BRAF). Mismatch repair deficiency was identified in 10% (4/39) of patients. Potentially actionable alterations were identified frequently in KRAS wild-type PDACs (30%, 12/40), in which nontubular-type carcinomas were significantly enriched with actionable alterations compared with tubular adenocarcinomas [67% (6/9) versus 16% (5/31); p = 0.007]. Finally, we investigated the precursors of PDACs in 13 pancreatectomy specimens from patients with KRAS wild-type PDAC. We identified three pancreatic intraepithelial neoplasias (PanINs) and two intraductal papillary mucinous neoplasms (IPMNs) harboring oncogenic fusions of ALK and BRAF and driver mutations in BRAF and AKT1. This study suggests that in the context of unmutated KRAS, PDAC is driven by alternative oncogenic mutations or fusions of RAS pathway genes, which may be introduced during the early phase of tumorigenesis. © 2025 The Author(s). The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland. Show less

Recent developments in mass spectrometry (MS) have revealed target antigens for membranous nephropathy (MN), including phospholipase A2 receptor and exostosin 1/exostosin 2 (EXT1/2). EXT1/2 are known antigens of autoimmune disease-related MN, especially membranous lupus nephritis. We describe the case of an elderly man who developed nephrotic syndrome followed by progressive renal dysfunction. A 78-year-old man presented with rapidly progressive renal dysfunction with proteinuria and hematuria. Three years previously, he had developed leg edema but did not receive any treatment. Laboratory tests showed elevated anti-nuclear antibody (Ab), anti-dsDNA Ab titer, and hypocomplementemia, indicating systemic lupus erythematous. Myeloperoxidase anti-neutrophil cytoplasmic Ab (ANCA) and anti-glomerular basement membrane (GBM) Ab were also detected. The renal pathologic findings were compatible with crescentic glomerulonephritis (GN), whereas non-crescentic glomeruli exhibited MN without remarkable endocapillary or mesangial proliferative change. Immunofluorescence microscopy revealed glomerular IgG, C3, and C1q deposition. All IgG subclasses were positive in glomeruli. Anti-PLA2R Ab in serum was negative. MS analysis was performed to detect the antigens of MN, and EXT1/2 was detected in glomeruli. Therefore, we reached a diagnosis of membranous lupus nephritis concurrent with both ANCA-associated vasculitis and anti-GBM-GN. The simultaneous occurrence of these three diseases is extremely rare. This is the first report of EXT1/2-related membranous lupus nephritis concurrent with ANCA-associated vasculitis and anti-GBM-GN. This case demonstrates the usefulness of MS in diagnosing complicated cases of MN. Show less

gp130-dependent signaling is known to play a critical role in the onset of heart failure. In that regard, cardiotrophin-1 (CT-1) activates several signaling pathways via gp130, and induces hypertrophy in neonatal rat cardiomyocytes. Among the mediators activated by CT-1, STAT3 is thought to be important for induction of cell hypertrophy, though its precise function in the CT-1 signaling pathway is not fully understood. In the present study, therefore, to better understand the significance of STAT3 activity in CT-1 signaling, we infected cultured cardiomyocytes with adenoviral vectors harboring a dominant-negative STAT3 mutant or one of two endogenous negative regulators of cytokine signaling via the Janus kinase (JAK)-signal transducer and activator of transcription (STAT) pathways [suppressor of cytokine signaling (SOCS) 1 and 3] and then examined their effects on three indexes of CT-1-induced cell hypertrophy: protein synthesis, secretion of brain natriuretic peptide and changes in cell surface area. In control cells, CT-1-induced both STAT3 phosphorylation and cell hypertrophy. Overexpression of dominant-negative STAT3 mutant suppressed CT-1-induced STAT3 phosphorylation, but did not affect cell hypertrophy. On the other hand overexpression of SOCS1 or SOCS3 inhibited both CT-1-induced STAT3 phosphorylation and cell hypertrophy. CT-1 also induced phosphorylations of ERK1/2 and ERK5 in cardiomyocytes, and those, too, were suppressed by overexpression of SOCSs. CT-1-induced cell hypertrophy was suppressed by overexpression of a dominant-negative MEK5 mutant, and not by overexpression of a dominant-negative MEK1 mutant. These findings indicate that the major pathway responsible for the hypertrophic responses to CT-1 is not JAK-STAT3 pathway nor MEK1-ERK1/2 pathway, but MEK5-ERK5 pathway. Show less