HRC抑制内质网应激增强失巢凋亡抵抗在肝癌中的作用及机制

Metastasis is the main reason for high mortality and poor prognosis of hepatocellular carcinoma (HCC). Our previous study showed that the histidine rich calcium-binding protein(HRC) was upregulated in HCC and it could promote HCC metastasis. Anoikis resistance is critical to tumor invasion and metastasis. Recent studies have shown that HRC plays a critical role in Ca2+-homeostasis by regulating calcium channel or calcium pump. Moreover, calcium dyshomeostasis can induce endoplasmic reticulum stress,which lead to anoikis. Up to now, the relationships among HRC, ERS and anoikis resistance have not been investigated. Our study also found that HRC inhibited ER stress in liver cancer cells，and our preliminary experiment demonstrated that HRC enhanced anoikis resistance, and ERS induced anoikis of HCC cells. So we suggest that HRC suppresses ERS by regulating Ca2+-homeostasis, which enhanced anoikis resistance to promote HCC invasion and metastasis. On the basis of these, our next project will study the effects of HRC and ERS on anoikis of HCC cells, how HRC regulates Ca2+-homeostasis and inhibits ERS at the state of anoikis in HCC, and animal experiment will be used to detect the effect of HRC-inhibited ERS on HCC invasion and metastasis. Clarify the role of HRC in the invasion and metastasis of HCC to obtain the potential intervention targets.

侵袭转移是肝癌疗效差、致死率高的主要原因。我们前期研究证实，钙结合蛋白HRC高表达与肝癌侵袭转移相关。失巢凋亡抵抗是肿瘤侵袭转移的关键。最新研究表明，HRC可通过调控钙通道或钙泵维持钙稳态；钙稳态失衡诱发内质网应激（ERS），后者可诱导失巢凋亡。肝癌中HRC、内质网应激、失巢凋亡抵抗之间的关系尚无研究。我们进一步研究证实，HRC可抑制内质网应激；且本项目预实验发现，HRC可增强细胞失巢凋亡抵抗能力，诱导ERS增加肝癌细胞失巢凋亡率。据此推测，HRC抑制内质网应激，增强失巢凋亡抵抗，促进肝癌侵袭转移；而这一作用又与HRC调控钙稳态相关。本项目拟观察HRC、ERS对肝癌细胞失巢凋亡的影响，筛选并验证失巢状态下HRC调控钙稳态的钙通道或钙泵，研究失巢状态下HRC抑制ERS的信号通路，动物水平验证HRC通过抑制ERS促进肝癌侵袭转移。阐明HRC在肝癌侵袭转移中的作用和机制，以期寻找潜在的干预靶点。

转移和复发是人类肝细胞癌患者高死亡率的主要原因。富含组氨酸的钙结合蛋白（HRC）在肝细胞癌（HCC）中表达上调，并且与肝癌转移密切相关。失巢凋亡抵抗和内质网应激可能对肝癌转移前的生存有着重要影响。然而到目前为止，在肝癌中HRC在失巢凋亡抵抗中的潜在作用机制与功能仍然未知。在这里，我们使用TCGA数据库分析HRC在肝癌中的表达及预后。此外我们还采用蛋白电泳、实时荧光定量PCR、流式细胞术、免疫组化和小动物荧光活体成像术等实验方法和技术，我们发现了HRC的临床价值及其对HCC对失巢凋亡抵抗的功能与意义。 HRC的阳性表达与肿瘤大小，有包膜和TNM分期相关。在悬浮培养的HCC细胞中，HRC的表达量显著增加。 HRC可以增强HCC细胞的失巢凋亡抵抗能力，并促进其在体内的转移。作用机制方面，失巢凋亡抵抗可能取决于内质网应激（ERS）。HRC可通过蛋白激酶RNA样ER激酶（PERK）-ATF4-CHOP信号转导轴抑制内质网应激，从而影响失巢凋亡增强其抵抗能力。此外，HRC可通过抑制内置网上SERCA2蛋白调节内质网应激关键效应分子CHOP的表达从而影响失巢凋亡增强其抵抗能力。总而言之，我们将HRC定义为参与失巢凋亡抵抗和HCC转移的新型候选癌基因，并为HCC提供新的潜在治疗靶点。