Department of General Surgery, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu 210029, P.R. China.
Department of Emergency Surgery, Affiliated Hospital of Nantong University, Nantong, Jiangsu 226001, P.R. China.
Int J Oncol. 2019 May;54(5):1625-1638. doi: 10.3892/ijo.2019.4753. Epub 2019 Mar 18.
Epidemiological data show that chronic stress has adverse effects on the incidence and progression of cancer. As a critical target organ for stress hormones, the stomach is frequently subjected to stress‑related injury. However, few reports regarding the association between stress and gastric cancer (GC) have been published. The present study aimed to investigate the effect of chronic stress on the growth and survival of GC, and the role of the autophagy process. A restraint‑stress procedure over 21 days was used to establish a chronic stress mouse model. Subcutaneous xenografts and gastric orthotopic xenografts were established in BALB/c nude mice. Alzet osmotic minipumps containing either PBS or propranolol hydrochloride was inserted on the nape of the neck 7 days prior to the initiation of restraint stress. The presence of autophagosomes and autolysosomes were examined by electron microscopy. The stress hormone norepinephrine significantly enhanced the proliferation of GC cells. By inhibiting adrenoreceptor expression, it was demonstrated that β2‑adrenergic receptor (ADRB2) was the specific β‑adrenergic receptor subtype responsible for catecholamine release. In addition, it was demonstrated that the induction of autophagy was a novel consequence of β2‑adrenergic activation in GC cells. This was demonstrated by the appearance of double‑membrane vesicles, punctuate GFP‑RFP‑microtubule‑associated protein 1 light chain 3 distribution in the cytoplasm and a corresponding increase in autophagic flux. Notably, norepinephrine‑induced autophagy was shown to have a tumor‑promoting role under conditions of chronic stress in vitro and in vivo. It was further demonstrated that, upon activation of cAMP‑response element binding protein, chronic stress promoted autophagic flux through the adenosine 5'‑monophosphate‑activated protein kinase‑unc‑51 like autophagy activating kinase 1 (AMPK‑ULK1) pathway. Tissue microarray analysis revealed a negative correlation between the expression of ADRB2 and autophagic marker p62/sequestosome‑1 in GC tumor samples. Additionally, high protein levels of ADRB2 correlated positively with tumor, node, metastasis stage and poor prognosis in patients with GC. These results establish a novel pathway that chronic stress activates tumor‑promoting autophagy to accelerate the progression of GC. The present study is the first, to the best of our knowledge, providing preclinical evidence that chronic stress serves a role in the progression of GC.
流行病学数据表明，慢性应激会对癌症的发生和进展产生不利影响。作为应激激素的关键靶器官，胃经常受到应激相关损伤。然而，关于应激与胃癌（GC）之间的关系，鲜有报道。本研究旨在探讨慢性应激对 GC 生长和存活的影响，以及自噬过程的作用。通过 21 天的束缚应激程序，建立慢性应激小鼠模型。在开始束缚应激前 7 天，在 BALB/c 裸鼠的颈背部插入含有 PBS 或盐酸普萘洛尔的 Alzet 渗透微型泵。通过电子显微镜检查自噬体和自噬溶酶体的存在。应激激素去甲肾上腺素显著增强 GC 细胞的增殖。通过抑制肾上腺素能受体表达，证实β2-肾上腺素能受体（ADRB2）是负责儿茶酚胺释放的特定β-肾上腺素能受体亚型。此外，研究表明，自噬的诱导是 GC 细胞中β2-肾上腺素能激活的一种新的后果。这表现为细胞质中双膜囊泡、点状 GFP-RFP-微管相关蛋白 1 轻链 3 分布以及自噬流的相应增加。值得注意的是，在体外和体内慢性应激条件下，去甲肾上腺素诱导的自噬具有促进肿瘤的作用。进一步研究表明，在 cAMP 反应元件结合蛋白激活后，慢性应激通过腺苷 5'-单磷酸激活蛋白激酶-unc-51 样自噬激活激酶 1（AMPK-ULK1）通路促进自噬流。组织微阵列分析显示，GC 肿瘤样本中 ADRB2 的表达与自噬标记物 p62/自噬体 1 呈负相关。此外，ADRB2 蛋白水平较高与 GC 患者的肿瘤、淋巴结、转移分期和预后不良呈正相关。这些结果建立了一条新的途径，即慢性应激激活促进肿瘤的自噬，从而加速 GC 的进展。本研究首次提供了临床前证据，表明慢性应激在 GC 的进展中起作用。
