en علوم مولکولی Molecular Sciences تحقیقی Original article <div style="text-align: justify;"><span style="font-size:14px;"><span style="line-height:2;"><span style="direction:rtl"><span style="unicode-bidi:embed"><span calibri=""><span dir="LTR" new="" roman="" times=""><span style="color:black"></span></span></span></span></span><span sans-serif="" style="font-family:Calibri,"><b><i><span new="" roman="" style="font-family:" times="">Background and <span style="color:black">Objectives: </span></span></i></b><span new="" roman="" style="font-family:" times=""><span style="color:black">Oral cancer relates to oral and intestinal microbiota composition. <i>Lactobacillus</i> species are considered probiotic bacteria due to their ability to modulate human immune responses and therapeutic effects. This study aimed to investigate the effects of <i>Lactobacillus plantarum</i> (<i>L. plantarum</i>) on TLR4 gene expression and its downstream pathways in a mouse model of oral cancer.<b><i></i></b></span></span></span><br> <span sans-serif="" style="font-family:Calibri,"><b><i><span new="" roman="" style="font-family:" times=""><span style="color:black">Material and Methods:</span></span></i></b><span new="" roman="" style="font-family:" times=""><span style="color:black"> This experimental study was conducted in the Stem Cell Research Center, Faculty of Modern Technologies, Golestan University of Medical Sciences, Gorgan, Iran, in 2021<i>. L. plantarum</i> strain ATCC 8014 was used in this study. Twenty-eight male Wistar rats were divided into four groups (n = 7). 4-Nitroquinoline 1-oxide (4NQO) was used to establish oral cancer in rats. A pathological examination was adopted to confirm cancer establishment. Rats were treated with probiotic <i>L. plantarum</i> before and after cancer development. After extracting RNA from blood and synthesizing cDNA, the ability of lactobacilli to modulate the expression of TLR4 genes was investigated by Real-Time PCR Methods (RT-PCR).</span></span><b><i><span new="" roman="" style="font-family:" times=""><span style="color:black"></span></span></i></b></span><br> <span sans-serif="" style="font-family:Calibri,"><b><i><span new="" roman="" style="font-family:" times=""><span style="color:black">Results: </span></span></i></b><span new="" roman="" style="font-family:" times=""><span style="color:black">In the present study, it was observed that after causing cancer and treating the animal with <i>L. plantarum</i>, the expression of the TLR4 gene decreased significantly (<i>P</i>-value < 0.05), which might, in turn, affect the downstream pathways, which included the decrease in the expression of BCL-2 and NF-ĸB genes. Accordingly, the expression of the NF-ĸB gene was significantly reduced in rats received <i>L. plantarum</i>gavaged for two weeks after cancer induction.<b><i></i></b></span></span></span><br> <span sans-serif="" style="font-family:Calibri,"><b><i><span new="" roman="" style="font-family:" times=""><span style="color:black">Conclusion:</span></span></i></b><b><i> </i></b><span new="" roman="" style="font-family:" times="">According to the obtained results, probiotic <i>L. plantarum</i> significantly affects the gene expression of NF-ĸB and TLR4 in cancerous rats. It was also shown that <i>L. plantarum</i> was more efficient in reducing TLR-4 and NF-ĸB genes expression when it was gavaged for 14 days after tumor induction.</span></span></span></span><span style="font-size:11pt"><span style="line-height:115%"><span sans-serif="" style="font-family:Calibri,"><span style="font-size:9.0pt"><span style="line-height:115%"><span new="" roman="" style="font-family:" times=""><span style="color:black"></span></span></span></span></span></span></span></div> Lactobacillus plantarum,Probiotics,Toll-Like Receptors,Apoptosis, 12 20 http://goums.ac.ir/jorjanijournal/browse.php?a_code=A-10-904-1&slc_lang=en&sid=1 Vahideh Faghani zadeh arshad_faghani@yahoo.com 10031947532846009048 0000000275014103 No Department of Microbiology, Damghan Branch, Islamic Azad University, Damghan, Iran Nazila Arbab Soleimani Nazila.Arbab@iau.ac.ir 10031947532846009049 0000000214852891 Yes Stem Cell Research Center, Golestan University of Medical Sciences, Gorgan, Iran Ayyoob Khosravi ayyoobfarsian@yahoo.com 10031947532846009050 0000000323401870 No Department of Molecular Medicine, Faculty of Advanced Medical Technologies, Golestan University of Medical Sciences, Gorgan, Iran mohammad mahdi forghanifard forghanifard@gmail.com 10031947532846009051 0000000276916897 No Departments of Biology, Damghan Branch, Islamic Azad University, Damghan, Iran.