Autoimmune hemolytic anemia (AIHA) is a rare comorbidity in colorectal cancer (CRC) and has an unknown etiology. Previously, we described an AIHA case secondary to CRC with ectopic band 3 expression. Herein, we investigated ectopic band 3 expression and erythrocyte membrane-bound IgG in a CRC cohort. Between September 2016 and August 2018, 50 patients with CRC and 26 healthy controls were enrolled in the present study. The expression of band 3 and SLC4A1 mRNA was observed in 97% of CRC surgical specimens. Although clinical AIHA was not observed in any patient with CRC, a direct antiglobulin test was positive in 10 of the patients in the CRC group (p = 0.01). Flow cytometry revealed significantly increased erythrocyte membrane-bound IgG among patients with CRC compared to healthy controls (mean ± standard deviation; 38.8 ± 4.7 vs. 29.9 ± 15.6, p = 0.012). Normocytic anemia was observed, including in cases negative for fecal occult blood, suggesting a shortened erythrocyte life-span due to increased membrane-bound IgG. Immunoprecipitation revealed increased anti-band 3 autoantibodies in patients' sera. Mouse experiments recapitulated this phenomenon. We also confirmed that band 3 expression is controlled by 5'AMP-activated protein kinase under hypoxic conditions. These findings increase our understanding of the etiology of cancer-related anemia.

中文翻译：

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结直肠癌中带 3 的异位表达诱导红细胞膜结合 IgG 增加，并可能导致免疫相关性贫血。

自身免疫性溶血性贫血 (AIHA) 是一种罕见的结直肠癌 (CRC) 合并症，病因不明。以前，我们描述了一个继发于具有异位带 3 表达的 CRC 的 AIHA 病例。在此，我们研究了 CRC 队列中的异位带 3 表达和红细胞膜结合 IgG。2016 年 9 月至 2018 年 8 月期间，50 名 CRC 患者和 26 名健康对照者参加了本研究。在 97% 的 CRC 手术标本中观察到带 3 和 SLC4A1 mRNA 的表达。尽管在任何 CRC 患者中均未观察到临床 AIHA，但 CRC 组中有 10 名患者的直接抗球蛋白试验呈阳性（p = 0.01）。流式细胞术显示，与健康对照组相比，CRC 患者的红细胞膜结合 IgG 显着增加（平均值 ± 标准差；38.8 ± 4.7 对 29.9 ± 15.6，p = 0.012)。观察到正细胞性贫血，包括粪便潜血阴性的病例，这表明由于膜结合 IgG 增加导致红细胞寿命缩短。免疫沉淀显示患者血清中抗带 3 自身抗体增加。小鼠实验重现了这一现象。我们还证实，在缺氧条件下，带 3 的表达受 5'AMP 活化蛋白激酶的控制。这些发现增加了我们对癌症相关性贫血病因的理解。我们还证实，在缺氧条件下，带 3 的表达受 5'AMP 活化蛋白激酶的控制。这些发现增加了我们对癌症相关性贫血病因的理解。我们还证实，在缺氧条件下，带 3 的表达受 5'AMP 活化蛋白激酶的控制。这些发现增加了我们对癌症相关性贫血病因的理解。