LIN00473 Promotes The Taxol Resistance Via MiR-15a-5p In Colon Cancer

Colonrectal cancer(CRC)is the third most prevalent malignancy wordwide and has a high mortality rate.CRC has become a major care and social-economic burden worldwide.Early diagnosis colon cancer can obtain relatively good therapeutic effects by timely treatment,currently,surgical treatment,postoperative adjuvant radiotherapy,chemotherapy and targeted thrapy.There are two important problems in the treatment of colon cancer:lack of effective markers to diagnose early;Patients are prone to drug resistance during and before chemotherapy,which resulting in treatment failure.Long non-coding RNAs(IncRNAs)participated into the initiation and progression of different diseases via direct regulation of proteins or indirect regulation of microRNA(miRNA)-target genes.LncRNA has been a hot field of tumor research,which can affect the proliferation,invasion,metastasis and apoptosis of tumor cells.Mounting evidences have uncovered the dysregulation of InRNA in many physiological and pathological processes of carcinogenesis including CRC,thus,it can serve as a marker for tumor diagnosis and therapeutic target.LINC00473 is a novel carcinoma-related LncRNA and that participated into tumor proliferation,chemotherapy resistance and human decidualization.Reports found that LINC00473 is a oncogene factor and is up-regulated in many cancers including stomach cancer and cervical cancer for tumor growth and metastasis,however,the function of LINC00473 in colon cancer is poorly understoodThe colon cancer tissues and relative normal tissues were collected and found that LINC00473 was overexpressed in colon cancer tissues when compared to which in normal tissues.Highly expressed LINC00473 predicted large tumor size,high TNM stage of colon cancer patients.It indicates that LINC00473 can be used as an early diagnostic marker in colon cancer.Interactions with miRNAs are critical mechanisms for LncRNAs to exert their function.Interestingly,the tumor suppressor miR-15a was down-regulated and negatively correlated with LINC00473 levels in colon cancer.This datas showed that LINC00473 harbored the binding sites for miR-15a and reduced its availability in CRC cell line HCT116.In this part,the regulation effect of LINC00473 on mir-15a-5p in colon cancer was confirmed,suggesting that LINC00473 may play a role in colon cancer by mir-15a-5p.Chemotherapy resistance is an important problem in the treatment of colon cancer and most patients fail because of drug resistance.It reported that the expression of LINC00473 is related to drug resistance.We found that compared to the HCT116,the HCT116/Taxol cell line had higher expression of LINC00473 but lower expression of miR-15a,indicating that LINC00473 could be associated with Taxol resistance.In order to verify whether the high expression of LINC00473 is an important factor leading to the drug resistance of paclitaxel,we knocked down the expression of LINC00473,we found that knockdown of LINC00473 restored the Taxol-induced cytotoxicity,inhibited the cell vitality,but these effects could be abrogated by the inhibition of miR-15a-5p.Those result showed that knockdown of LINC00473 contributed to the recovery of sensitivity to Taxol in HCT116/Taxol cells via up-regulation of tumor suppressor miR-15a,leading to the inhibition of tumor growth and the ability of migration or invasion.Mechanistically,the BCL-2-related anti-apoptosis pathway was activated and the multidrug-resistant(MDR)genes LRP,MDR1 were up-regulated by LINC00473 mediated miR-15a-5p.Finally,the sensitivity of the tumor to paclitaxel was further detected by using the nude mouse,The nude mice were administrated of conditional tumor cells with/without LINC00473 knockdown and then were treated with Taxol.The results indicated that the mice with LINC00473 knockdown efficiently responded to the treatment of Taxol and inhibited tumor growth.This tumor inhibition was associated with the up-regulation of tumor suppressor miR-15a-5p.These data indicated knockdown of LINC00473 in vivo recovered the availability of miR-15a and overcame the Taxol resistance in colon cancer and The targeted inhibition of LINC00473 could promote the expression of miR-15a-5p and restore the sensitivity of the tumor to Taxol.In conclusion,this study demonstrates that,LINC00473 is highly expressed in colon cancer,and the expression of LINC00473 is associated with the staging of colon cancer.It is also confirmed that LINC00473 can directly bind and inhibit the expression of miR-15a-5p,which will promote the resistance of colon cancer cells to Taxol.Down-regulation of LINC00473 was able to activate Bcl-2 related apoptosis pathway and promote the expression of multidrug resistance gene by miR-15a-5p to restore the sensitivity of Taxol and enhance the therapeutic effect of Taxol.This project not only confirm the validity of the LINC00473 as a marker for colon cancer,but also is providing clues into targeted IncRNA alleviate chemotherapy drug resistance,to find more effective ways of cancer therapy to provide theoretical basis.This project will provide theoretical basis for finding more active and effective treatment for colon cancer.