Investigation of Endocannabinoid System Signalling Pathways and Their Regulations in Endometrial Carcinoma

In the UK, endometrial cancer (EC) is the 4th most common cancer and its incidence is rapidly rising. This study aimed to elucidate the role of the endocannabinoid system (ECS) in the pathogenesis of EC. Plasma and endometrial tissues levels of anandamide (AEA), palmitoylethanolamide (PEA) and oleoylethanolamide (OEA) quantified by UHPLC from atrophic and EC group. Using the qRT-PCR and immunohistochemistry (IHC), CB1, CB2, FAAH, NAPE-PLD, GPR55 and TRPV1, mRNAs and protein levels was evaluated, respectively. The effects of in-vitro exposure of Ishikawa cell-line to AEA, OEA, PEA and capsaicin were evaluated. Plasma and tissue AEA levels were significantly (p<0.05) higher in EC than control, as were PEA levels. Logistic regression raised the area under the ROC curve (AUC) from 0.781 for plasma AEA, 0.857 for PEA and 0.543 for OEA to a combined AUC of 0.933 for EC diagnosis. The transcript level of FAAH was 75% lower in EC and NAPE-PLD levels were more variable. Histomorphometric analysis of FAAH and NAPE-PLD staining complements the transcript data. CB1 and CB2 mRNA were significantly decreased by 90% (p< 0·0004) and 80% (p< 0·0001), respectively, compared with control and these was supported by the IHC. In the EC, GPR55 mRNA were significantly raised (p<0.0020) compared with control and its protein expressions were markedly stained in EC tissues. TRPV1 receptor transcript levels were significantly reduced (p<0.0054) in EC compared with controls and markedly decreased in EC by IHC. Cancer cell growth in-vitro was decreased by the endocannabinoids in a pseudo dose-dependent and time-dependent manner. The endocannabinoids might prevent cancer cell growth by inhibiting cell proliferation or by activating apoptosis. This idea was tested using BAX/Bcl-2 and Ki-67 expression and found to be due to decrease cell proliferation. It is evident that there is an apparent perturbation of ECS at tissue and plasma levels and this could be used as diagnostic and prognostic markers with potential therapeutic target for the prevention EC.