Retinoic acid morpholine amide (RAMA) inhibits expression of Fas ligand through EP1 receptor in colon cancer cells

Abstract

Among the members of tumour necrosis factor family Fas ligand on binding to its receptor strongly induces apoptosis of tumour-infiltrating lymphocytes (TIL). Thus, FasL acts as an inhibitor of anti-tumour immune response. The present study demonstrates that retinoic acid morpholine amide (RAMA) significantly suppresses FasL expression in colon cancer cells in a dose- and time-dependent manner. The suppression of FasL mRNA and proteins was significant at a concentration of 30 μM after 48 h in CLT85 and HT26 colon cancer cells. There was around 2.6- and 3.2-fold decrease in FasL mRNA after incubation with 30 μM of RAMA in CLT85 cells and HT26 cells, respectively. The results from Western blot showed a decrease in FasL mRNA and protein expression in both CLT85 and HT26 cells after suppression of cyclooxygenase (COX)-2 and COX-1 by RNAi. However, when COX-2-specific silencer RNA (siCOX-2)- and siCOX-1-treated CLT85 and HT26 cells were exposed to RAMA, inhibition of FasL expression was further suppressed. The siCOX-2-treated CLT85 and HT26 cells on exposure to RAMA showed ∼87 and ∼54 % reduction in FasL mRNA, respectively. Co-culture of Jurkat T cells with RAMA-treated HT26 and CLT85 cells decreased the viability of Jurkat T cells by only 2 and 4.3 %, respectively, compared to 19.5 and 37.3 % in control HT26 and CLT85 cells. The results from real-time reverse transcription polymerase chain reaction (RT-PCR) and immunoblotting showed that suppression of EP1 prevented RAMA-induced FasL suppression in CLT85 cells at both the mRNA and protein levels. Thus, RAMA can be a potent therapeutic agent for the treatment of colon tumours.

Photophysical properties of a newly synthesized unsymmetrically substituted zinc phthalocyanine

“…Morpholine and its derivatives are used as solvents, corrosion inhibitors, rubber additives, antioxidants, as well as in the production of drugs and herbicides. Morpholine derivatives are also of interest as they show biological activities such as anti-inflammatory, analgesic, antidepressant, and antitumor (14)(15)(16)(17).…”

Synergetic Effect of EP₁ Receptor Antagonist and (-)-Epigallocatechin-3-gallate in Hepatocellular Carcinoma

“…EGFR phosphorylation and cell invasiveness induced by PGE 2 were blocked after EP 1 receptor knockdown by siRNA, or by the EP 1 receptor antagonist ONO-8711 [12]. Pharmacological and genetic studies show the selective EP 1 inhibitor significantly reduced colon cancer development, indicating this receptor plays a role in colon carcinogenesis [13]. A research showed that long-term administration of ONO-8711 in rat diet reduced azoxymethane-induced colon cancer incidence, multiplicity and volume of colon carcinomas [14].…”