A role for endothelial nitric oxide synthase in intestinal stem cell proliferation and mesenchymal colorectal cancer

Abstract

BackgroundNitric oxide (NO) has been highlighted as an important agent in cancer-related events. Although the inducible nitric oxide synthase (iNOS) isoform has received most attention, recent studies in the literature indicate that the endothelial isoenzyme (eNOS) can also modulate different tumor processes including resistance, angiogenesis, invasion, and metastasis. However, the role of eNOS in cancer stem cell (CSC) biology and mesenchymal tumors is unknown.ResultsHere, we show that eNOS was significantly upregulated in VilCreERT2Apcfl/+ and VilCreERT2Apcfl/fl mouse intestinal tissue, with intense immunostaining in hyperproliferative crypts. Similarly, the more invasive VilCreERT2Apcfl/+ Ptenfl/+ mouse model showed an overexpression of eNOS in intestinal tumors whereas this isoform was not expressed in normal tissue. However, none of the three models showed iNOS expression. Notably, when 40 human colorectal tumors were classified into different clinically relevant molecular subtypes, high eNOS expression was found in the poor relapse-free and overall survival mesenchymal subtype, whereas iNOS was absent. Furthermore, Apcfl/fl organoids overexpressed eNOS compared with wild-type organoids and NO depletion with the scavenger carboxy-PTIO (c-PTIO) decreased the proliferation and the expression of stem-cell markers, such as Lgr5, Troy, Vav3, and Slc14a1, in these intestinal organoids. Moreover, specific NO depletion also decreased the expression of CSC-related proteins in human colorectal cancer cells such as β-catenin and Bmi1, impairing the CSC phenotype. To rule out the contribution of iNOS in this effect, we established an iNOS-knockdown colorectal cancer cell line. NO-depleted cells showed a decreased capacity to form tumors and c-PTIO treatment in vivo showed an antitumoral effect in a xenograft mouse model.ConclusionOur data support that eNOS upregulation occurs after Apc loss, emerging as an unexpected potential new target in poor-prognosis mesenchymal colorectal tumors, where NO scavenging could represent an interesting therapeutic alternative to targeting the CSC subpopulation.Electronic supplementary materialThe online version of this article (10.1186/s12915-017-0472-5) contains supplementary material, which is available to authorized users.

Nitric Oxide (NO) and NO Synthases (NOS)-Based Targeted Therapy for Colon Cancer

“…It has been reported that iNOS is highly expressed in almost 60% of human colon adenomas, whereas it is low or undetectable in normal intestinal tissues [27,45]. Interestingly, the expression level of iNOS attenuated in an advanced tumor with metastasis, and was absent in human mesenchymal CRC subtypes [46].…”

“…Recent studies revealed that eNOS might be involved in various tumor hallmarks, including invasion, metastasis, angiogenesis, and resistance [61,62]. Therefore, eNOS could act as a marker for poor prognosis in human cancer [46,63]. Peñarando et al explored the mechanism of eNOS in mesenchymal colorectal cancer and cancer stem cells.…”

Camel milk Whey Inhibits Inflammatory Colorectal Cancer Development Via Down regulation of Pro-inflammatory Cytokines in Induced AOM/DSS Mouse Model

“…However, there is a huge controversy about the role of iNOS in colon cancer (Ambs et al, 1998;Moochhala et al, 1996;Peñarando et al, 2018) Treatment of colitis induced animals by CM whey reduced the expression level of iNOS gene (Fig.2). This indicates the anti-inflammatory activity of CM whey as iNOS expression was found to correlate with the severity of DSS-induced colitis (Seril et al, 2003).…”

“…The iNOS isoform has been shown to be the predominant enzyme that promotes tumor progression through nitrogen oxide (NO) production. Several studies indicated that the endothelial isoenzyme (eNOS) can also modulate different tumor processes including resistance, angiogenesis, invasion and metastasis (Peñarando et al, 2018;Thomsen et al, 1997).…”

Abnormal Expression of NOS3 and Association with Clinical Outcome are Highly Cancer Dependent as Revealed through Pan-Cancer Analysis

“…Circulating NOS3 levels were signi cantly correlated with progression-free survival and overall survival (OS) of metastatic colorectal cancer patients (9). Another research in mesenchymal colorectal cancer patients reported that NOS3 upregulation occurs after Apc loss which was associated with poor prognosis (10). In breast cancer, the increasing expression of NOS3 was reported to be a pro-angiogenic factor (11).…”