The Molecular Biomarkers Expression In Colorectal Cancer And Gastroenteropancreatic Neuroendocrine Tumor: Associations With Clinical Outcomes

Background: Colorectal cancer (CRC) is the most common malignant tumors of thedigestive system. Gastroenteropancreatic neuroendocrine tumor (GEP-NET) accounts for65-75%of all neuroendocrine tumors and the incidence is increasing gradually. SMO (theofficial symbol for “smoothened, frizzled family receptor”) is an important component ofthe hedgehog signaling pathway, which has been implicated in various human cancers.However, significance of SMO expression in CRC remains unclear. Clinical studies havesuggested anti-tumor efficacy of somatostatin analog (SSA) combination with somatostatinreceptors (SSTRs) in the treatment of NET. However, the efficacy of SSA combinationwith SSTRs in GEP-NET remains unclear. Clinical studies have suggested efficacy ofvascular endothelial growth factor (VEGF) inhibitors in the treatment of advanced NET,although that of VEGF pathway in GEP-NET is uncertain.Objective: To evaluate clinical, pathological and prognostic associations of molecularbiomarkers with CRC and GEP-NET.Methods:(1)1.Using a database of735CRC in the Nurse’s Health Study (NHS) andthe Health Professionals Follow-up Study (HPFS), TMAs were constructed.2. Clinical,pathological, molecular features and follow-up were collected (constructed by others).3.Molecular analysis of cancer tissue (constructed by others).4. Immunohistochemistry (IHC)for SMO was carried out.5.Statistics analysis.(2)1.785patients confirmed NET recruited toa study at Dana-Farber Cancer Institute (DFCI). TMA blocks were designed from195GEP-NET patients.2. Clinical, pathological, molecular features and follow-up werecollected (constructed by others).3. SSTR1, SSTR2, SSTR3, SSTR5expression wasdetected by IHC.4. Statistics analysis.(3)1.785patients confirmed NET were recruited to astudy at DFCI. TMA blocks were designed from195GEP-NET patients.2. Clinical,pathological, molecular features and follow-up were collected (constructed by others).3. VEGFA, VEGFR1(FLT1) and VEGFR2(KDR) expression was detected by IHC.4.Statistics analysis.Results:(1) SMO expression was positively associated with KRAS mutation (P=0.0027), and inversely associated with phosphorylated AKT expression (P <0.0001),BRAF mutation (P=0.0026), CTNNB1nuclear localization (P=0.0005) and CIMP-highstatus (P=0.0035). Phosphorylated AKT expression [multivariate OR=0.48;95%confidence interval (CI),0.34-0.67; P <0.0001] and CTNNB1nuclear localization (OR=0.48;95%CI,0.35-0.67; P <0.0001) were significantly associated with SMO expression.We observed a borderline significant interaction between SMO expression and CIMP statusin CRC-specific survival (Pinteraction=0.035, given multiple testing significance level wasadjusted to P=0.0033).(2) Within172primary tumors, high expression of SSTR2was afavorable prognostic factor, and was associated with improved overall survival (OS)(multivariate HR0.44, P=0.019). In patients with metastatic small intestinalneuroendocrine tumor (SINET)(n=75), high expression of SSTR2was also associated withimproved OS (multivariate HR0.36, P=0.0083). In SSA-treated SINET patients, highexpression of SSTR2was associated with improved PFS (multivariate HR0.38, P=0.0084; median PFS:2.8years for SSTR2-high v1.3years for SSTR2-low). There was nosignificant association between SSTR1, SSTR3, SSTR5and clinical outcomes.(3) Among173primary GEP-NET, high expression of VEGFA was associated with shorter OS(multivariate HR,2.14; P=0.03) whereas high expression of VEGFR1was associated withimproved OS (multivariate HR,0.46; P=0.03). In45non-metastatic SINET patients, highexpression of VEGFR2was associated with shorter disease free survival (DFS)(multivariate HR,4.17; P=0.026). In76metastatic SINET patients, high expression ofVEGFA was also associated with shorter OS (multivariate HR,3.13; P=0.013). Thebevacizumab-treated SINET patients with VEGFA-high SINET (9of19) experienced somePFS improvement (median PFS:12.6months for VEGFA-high v6.7months forVEGFA-low).Conclusions:1. Our data reveal novel potential associations between the hedgehog,the WNT/CTNNB1, and the PI3K (phosphatidylinositol-4,5-bisphosphonate3-kinase)/AKT pathways, supporting pivotal roles of SMO and hedgehog signaling inpathway networking; SMO expression in CRC may interact with CIMP status to affect patient prognosis.2.High expression of SSTR2appears to be a favorable prognostic factorin patients with GEP-NET and SINET patients treated with SSA, as well as a favorablemarker of SSA treatment; there was no significant association between SSTR1, SSTR3,SSTR5expression with prognosis of GEP-NET,SINET and those treated with SSA.3.Expression of VEGFA and VEGFR2appears to be adverse prognostic factor andexpression of VEGFR1may be a favorable prognostic factor in GEP-NET includingSINET; expression of VEGF pathway components may be predictive markers in SINET patientstreated with bevacizumab.