| [Background and Purpose]Colorectal cancer (CRC) is one of the hot spots on cancer research. Microsatelliteinstability(MSI) CRC characterized by DNA microsatellite repeat length changebecomes more and more attention. The Microsatellite means exist in various parts of thehuman genome multiple tandem repetitive DNA repeat sequence of1-6nucleotidesrepeated10-60times a unit. The repetitive sequences, including five nucleotide markers,MSI can be diagnostic microsatellite instability-high (MSI-H) because of two or morethan two markers be detected; appear one MSI marker diagnosis for microsatelliteinstable-low,(MSI-L); five markers did not show MSI can be diagnosed microsatellitestability(MSS), MSI and MSS CRC suggested different trends and prognosis.Retinoic acid (RA), also known as retinoic acid or vitamin A acid, is the one of thevitamin A’s derivatives,which could inhibit the growth of a variety of tumor cells,promote apoptosis and induction of differentiation. RA including a variety of cis andtrans isomers such as9-cis-retinoic acid,13-cis-retinoic acid and all-trans retinoicacid (ATRA). The most stable RA is the third-generation retinoid–ATRA. RA onlyplays function that inhibiting tumor cells proliferation and promote apoptosis of tumorcells by binding to a receptor. Retinoic acid receptor including nuclear retinoic acidreceptors(RAR) and retinoid X receptors (RXR). Both of them are the retinoic acid receptor family member,which is involved in RA signaling that mediates the and alsoincludes three kinds of subtypes of α, β, γ. In the current clinical, CRC, especially inthe MSS CRC and MSI CRC, ATRA lack of a clear effect. In this article, MSI and MSScancer cells are processed by using ATRA in different concentrations, and observedtheir proliferation and retinoic acid receptors RARs-α mRNA expression and apoptoticprotein expression. We will compare the two on the above aspects.Our purpose is theimpact of ATRA on the MSI and MSS CRC to provide useful scientific basis fortreatment of CRC pathogenesis, and understanding of ATRA on the possible role of thepathogenesis of serrated lesions indirectly.[Method]MSI cell line LOVO and MSS cell line SW480were cultured in medium.During theexperiment, each group were treated with different concentration of ATRA, andnegative control and RARs-α inhibitors as control groups. Proliferation, expression ofRAR-α mRNA and apoptosis proteins caspase-3,caspase-8were detected and analysedby using the MTT assay, RT-PCR, and Western-blot technique.[Results]1. MTT assay found that the two cell lines treated with ATRA showed growth inhibitionand the higher of concentration of ATRA and the more obvious effect. When addingRARs-αinhibitors ATRA, the inhibition effect is significantly reduced.2. RT-PCRmethod detected the expression of RAR-α mRNA in two cell lines. After treated withATRA, the expression of RAR-α mRNA were significantly increased comparing withnegative control group (P <0.05). Also SW480ATRA cell line and LOVO ATRA cellline were statistically significant difference (P <0.05),and the mean optical density ratioanalysis found that the expression of RAR-αmRNA in SW480cell line is higher than inLOVO cell line. When adding the retinoic acid receptor inhibitor, the expression of RARα-mRNA in two cell line were no difference comparing with the negative controlgroup (P>0.05).3. Western-blot method detected the expression of apoptotic proteincaspase-3, caspase-8in two types of cell lines after adding ATRA. The results showedthe expression of caspase-3, caspase-8were significantly increased compared withnegative control group (P <0.05), while after adding to the retinoic acid receptorinhibitor, the expression of caspase-3, caspase-8in two cells comparing with negativecontrol group were no difference (P>0.05). Also The caspase-3, caspase-8expression inSW480ATRA and the LOVO ATRA cell lines were statistically significant difference(P<0.05),and the mean optical density ratio analysis found that the expression ofcaspase-3, caspase-8in SW480were higher than in LOVO cell line.(P <0.05).[Conclusion]1ATRA can inhibit cell proliferation, and induce apoptosis and stimulat expression ofreceptor on MSS CRC cells and MSI CRC cells.2Comparing of the effect in inhibit cell proliferation, induce apoptosis, promoting theexpression of RARs on two cell lines, The effcts in MSS cells is more clear than inMSI cells.3The RARs inhibitor can effectively inhibit ATRA effects on tumor cells, So ATRAonly binding with its receptor can take its effection.4. ATRA take the role of the inhibition on the MSI and MSS cancer cells.The inhibitionwould be weakened after applicating ATRA receptor inhibitors.It’s indirectly suggestthat the lack of ATRA and retinoic acid substances may be related to the incidence ofcolorectal serrated lesions... |
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