The therapeutic efficacy of immune checkpoint inhibitors (ICIs) in patients with hepatocellular carcinoma (HCC) is profoundly influenced by the tumor immune microenvironment (TIME), where tumor-associated macrophages (TAMs) expressing programmed death-ligand 1 (PD-L1) serve as key modulators of immune suppression and tumor progression. Although PD-L1(+) TAMs have attracted increasing attention, their precise immunological functions in patients with HCC remain incompletely understood. In this study, we conducted an integrated analysis combining single-cell transcriptomics, spatial profiling, in vitro functional assays, and in vivo therapeutic modeling to clarify the role of PD-L1(+) TAMs in HCC. Single-cell RNA sequencing of tumor samples from patients with HCC (GSE189903) revealed that intratumoral PD-L1(+) TAMs were enriched for immune-related signaling pathways and expressed chemokines including CXCL9, CXCL10, and CXCL11. In vitro, GM-CSF-induced PD-L1(+) macrophages promoted CD8(+) T cell exhaustion, characterized by increased expression of TIM3 and suppression of cytotoxic molecules such as GZMB. Spatial analysis using multiplex immunofluorescence staining of surgical specimens from 113 patients with HCC demonstrated that close proximity between PD-L1(+) TAMs and CD8(+) T cells within tumors was an independent predictor of early postoperative recurrence and poor outcome. Moreover, in a murine orthotopic liver cancer model, the combination of anti-GM-CSF and anti-PD-L1 antibodies inhibited the differentiation of PD-L1(+) TAMs, reduced their contact with CD8(+) T cells, alleviated T cell exhaustion, and potentiated antitumor immunity. These findings highlight the critical contribution of PD-L1(+) TAMs to immune evasion in patients with HCC and support their therapeutic targeting as a strategy to enhance ICI responses.

The present study aimed to establish a novel isolation strategy for circulating tumor cells (CTCs) using a microcavity array (MCA) system and to evaluate the clinical significance of CTCs in hepatocellular carcinoma (HCC). We examined recovery rates of HCC cell lines spiked into whole blood in MCA assay. Circulating tumor cells were isolated from peripheral blood samples (3 mL) of 7 healthy donors (HD), 14 patients with liver cirrhosis (LC), and 31 patients with HCC using the MCA system. Additionally, we investigated the mRNA expression of liver‐specific genes in isolated CTCs using qPCR. The recovery rates were 65.1% (HepG2), 76.7% (HuH7), and 99.0% (PLC/PRF/5). In HD and patients with LC and HCC, the CTC positivity rate (CTCs ≥10) and average CTC number were as follows: HD 0% and 0.1, LC 14.3% and 5.3, HCC 54.8% and 47.6, respectively. The CTC positivity rate in HCC was significantly higher than that in LC (p < 0.05). The number of CTCs was significantly higher in metastatic HCC (102.2 ± 160.6) than in localized HCC (8.2 ± 7.7) (p < 0.05). The expression of AFP, glypican‐3, EpCAM, and albumin (ALB) genes was detected in isolated CTCs. The positive CTCs (CTCs ≥10) significantly reduced the cumulative survival in patients with HCC (p = 0.025), especially in localized patients with HCC (p = 0.046). The newly developed MCA system has the potential to isolate CTCs from HCC with high sensitivity, and mRNA expression could be measured from CTCs. Identification of positive CTCs can help predict clinical outcome of patients with HCC. Thus, analysis of CTCs in patients with HCC may provide important information as a novel biomarker in disease progression.

Arachidonic acid 5-lipoxygenase (5-LOX), an enzyme that synthesizes leukotrienes (LTs), is involved in cancer development including proliferation, invasion, metastasis and drug resistance. However, the functional role of 5-LOX in hepatocellular carcinoma (HCC) remains to be elucidated. In this study, we analyzed the contribution of 5-LOX in HCC progression and investigated the potential of targeted therapy. Analysis of 86 resected HCC specimens and the clinical data of 362 cases of liver cancer from The Cancer Genome Atlas Liver Hepatocellular Carcinoma dataset, showed that 5-LOX expression was associated with postoperative survival. The cancer proliferative and stem cell potential were correlated with the levels of 5-LOX in CD163(+) tumor-associated macrophages (TAMs). In an HCC mouse model, CD163(+) TAMs expressed 5-LOX and produced LTB4 and LTC/D/E4; the 5-LOX inhibitor, zileuton, suppressed HCC progression. LTB4 and LTC/D/E4 promoted cancer proliferation and stem cell capacity via phosphorylation of extracellular signal-regulated kinase 1/2 and stem cell-associated genes. Taken together, we identified a novel mechanism of HCC progression in which CD163(+) TAMs express 5-LOX and produce LTB4 and LTC/D/E4, thereby enhancing the proliferative and stem cell potential of HCC cells. Furthermore, inhibition of 5-LOX activity regulates HCC progression, suggesting it has potential as a new therapeutic target.

Metastasis to the pituitary gland is extremely rare and is often detected incidentally by symptoms associated with endocrine dysfunction. Breast and lung cancer are the most common primary metastasizing to pituitary gland. Metastasis from hepatocellular carcinoma to the pituitary gland is extremely rare, with only 10 cases having been previously reported. We present here the first case of pituitary metastasis of hepatocellular carcinoma presenting with panhypopituitarism diagnosed by magnetic resonance imaging. We report the case of an 80-year-old Japanese woman who presented with the sudden onset of hypotension and bradycardia after having previously been diagnosed with hepatocellular carcinoma. Based on low levels of pituitary hormones, she was diagnosed with panhypopituitarism caused by metastasis of the hepatocellular carcinoma to the pituitary gland. Magnetic resonance imaging with arterial spin-labeling was effective in the differential diagnosis of the intrasellar tumor. The patient died despite hormone replacement therapy because of hypovolemic shock. Metastasis to the pituitary gland causes various non-specific symptoms, so it is difficult to diagnose. The present case emphasizes the importance of diagnostic imaging in identifying these metastases. Clinicians should consider the possibility of pituitary metastasis in patients with malignant tumors who demonstrate hypopituitarism.