Laboratorio de Biología Molecular y Apoptosis, Instituto de Investigaciones Médicas Alfredo Lanari, IDIM-UBA-CONICET, Facultad de Medicina, Universidad de Buenos Aires, Combatientes de Malvinas 3150. Cuerpo II, Piso 1, C1427ARO, Buenos Aires, Argentina.
CONICET, Buenos Aires, Argentina.
Cell Oncol (Dordr). 2021 Jun;44(3):627-641. doi: 10.1007/s13402-021-00589-x. Epub 2021 Feb 22.
CFTR mutations not only cause cystic fibrosis, but also increase the risk of colorectal cancer. A putative role of CFTR in colorectal cancer patients without cystic fibrosis has so far, however, not been investigated. RAC3 is a nuclear receptor coactivator that has been found to be overexpressed in several human tumors, and to be required for maintaining cancer stemness. Here, we investigated the functional relationship between CFTR and RAC3 for maintaining cancer stemness in human colorectal cancer.
Cancer stemness was investigated by analysing the expression of stem cell markers, clonogenic growth and selective retention of fluorochrome, using stable transfection of shCFTR or shRAC3 in HCT116 colorectal cancer cells. In addition, we performed pathway enrichment and network analyses in both primary human colorectal cancer samples (TCGA, Xena platform) and Caco-2 colorectal cancer cells including (1) CD133+ or CD133- side populations and (2) CFTRwt or CFTRmut cells (ConsensusPathDB, STRING, Cytoscape, GeneMANIA).
We found that the CD133+ side population expresses higher levels of RAC3 and CFTR than the CD133- side population. RAC3 overexpression increased CFTR expression, whereas CFTR downregulation inhibited the cancer stem phenotype. CFTR mRNA levels were found to be increased in colorectal cancer samples from patients without cystic fibrosis compared to those with CFTR mutations, and this correlated with an increased expression of RAC3. The expression pattern of a gene set involved in inflammatory response and nuclear receptor modulation in CD133+ Caco-2 cells was found to be shared with that in CFTRwt Caco-2 cells. These genes may contribute to colorectal cancer development.
CFTR may play a non-tumor suppressor role in colorectal cancer development and maintenance involving enhancement of the expression of a set of genes related to cancer stemness and development in patients without CFTR mutations.
CFTR 突变不仅会导致囊性纤维化，还会增加结直肠癌的风险。然而，目前尚未研究 CFTR 在无囊性纤维化的结直肠癌患者中的潜在作用。RAC3 是一种核受体共激活因子，已在多种人类肿瘤中发现过度表达，并被发现是维持癌症干性所必需的。在这里，我们研究了 CFTR 和 RAC3 之间的功能关系，以维持人类结直肠癌中的癌症干性。
通过分析干细胞标志物的表达、克隆形成生长和荧光染料的选择性保留，使用稳定转染 HCT116 结直肠癌细胞中的 shCFTR 或 shRAC3 来研究癌症干性。此外，我们在原发性人结直肠癌样本（TCGA、Xena 平台）和包括（1）CD133+或 CD133-侧群和（2）CFTRwt 或 CFTRmut 细胞（ConsensusPathDB、STRING、Cytoscape、GeneMANIA）的 Caco-2 结直肠癌细胞中进行了途径富集和网络分析。
我们发现 CD133+侧群表达的 RAC3 和 CFTR 水平高于 CD133-侧群。RAC3 过表达增加 CFTR 表达，而 CFTR 下调抑制癌症干性表型。与 CFTR 突变患者相比，无囊性纤维化的结直肠癌患者的结直肠癌样本中 CFTR mRNA 水平升高，并且这与 RAC3 的表达增加相关。在 CD133+Caco-2 细胞中涉及炎症反应和核受体调节的基因集的表达模式与 CFTRwt Caco-2 细胞中的表达模式共享。这些基因可能有助于结直肠癌的发生。
CFTR 可能在涉及增强与 CFTR 突变患者无相关性的一组与癌症干性和发展相关的基因表达的结直肠癌发生和维持中发挥非肿瘤抑制作用。
