Signal regulatory protein alpha (SIRPα) is a type I transmembrane protein that inhibits macrophage phagocytosis of tumor cells upon interaction with CD47, and the CD47‐SIRPα pathway acts as an immune checkpoint factor in cancers. This study aims to clarify the clinical significance of SIRPα expression in esophageal squamous cell carcinoma (ESCC). First, we assessed SIRPα expression using RNA sequencing data of 95 ESCC tissues from The Cancer Genome Atlas (TCGA) and immunohistochemical analytic data from our cohort of 131 patients with ESCC. Next, we investigated the correlation of SIRPα expression with clinicopathological factors, patient survival, infiltration of tumor immune cells, and expression of programmed cell death‐ligand 1 (PD‐L1). Overall survival was significantly poorer with high SIRPα expression than with low expression in both TCGA and our patient cohort (P < .001 and P = .027, respectively). High SIRPα expression was associated with greater depth of tumor invasion (P = .0017). Expression of SIRPα was also significantly correlated with the tumor infiltration of M1 macrophages, M2 macrophages, CD8+ T cells, and PD‐L1 expression (P < .001, P < .001, P = .03, and P < .001, respectively). Moreover, patients with SIRPα/PD‐L1 coexpression tended to have a worse prognosis than patients with expression of either protein alone or neither. Taken together, SIRPα indicates poor prognosis in ESCC, possibly through inhibiting macrophage phagocytosis of tumor cells and inducing suppression of antitumor immunity. Signal regulatory protein alpha should be considered as a potential therapeutic target in ESCC, especially if combined with PD‐1‐PD‐L1 blockade.
BackgroundPrimary amelanotic malignant melanoma of esophagus, which is a subtype of primary malignant melanoma of the esophagus (PMME), is a very rare disease with a poor prognosis. We herein report a case of the amelanotic type of PMME.Case presentationAn 86-year-old woman was admitted to our hospital with symptoms of dysphagia. An endoscopic examination and constructed radiography revealed an elevated and semipedunculated lesion with an ulcer in the lower thoracic esophagus accompanied by another submucosal lesion of the esophagus. She was diagnosed with esophageal squamous cell carcinoma by a preoperative endoscopic biopsy. We performed thoracoscopy- and laparoscopy-assisted subtotal esophagectomy with lymphadenectomy. Based on the surgical specimens, although there were no melanocytes, we made a diagnosis of a malignant melanoma immunohistochemically; the tumor cells were positive for S-100 protein and HMB45 focally and partially for Melan-A.ConclusionWe experienced a case of primary amelanotic malignant melanoma, and the patient has remained disease-free for 1 year since the surgery. Since the diagnosis of amelanotic type of PMME is difficult, it should be made by the combination of a morphological examination, pathological examination, and immunohistochemistry.
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