MicroRNAs (miRNAs) are a class of small, single-stranded non-coding RNAs that act as important regulators of gene expression and are involved in a number of important processes in life. A large number of studies have suggested that dysregulation of miRNA expression may be an important part of the mechanism of human tumorigenesis and progression. MiR-155-5p is mainly regarded as an oncomiR that acts on multiple target genes to participate in tumor progression, although it has been suggested to possess cancer growth suppressor effects. In this paper, we summarize the effects of miR-155-5p on cancer cell proliferation, invasion, migration, and drug resistance in various tumor types and elucidate its value as a possible potential marker in assisting diagnosis.

Malignant tumors have become the main cause of human death.With the prolonged use of chemotherapeutic drugs during the treatment process,tumor cell resistance is also constantly increasing.long non-coding RNA(lncRNA)is an important mem-ber of the non-coding RNA family.Cancer susceptibility candidate 2(CASC2)is a type of long non-coding RNA,high expression of CASC2 can inhibit tumor cell development and reduce drug resistance of tumor cells by promoting apoptosis,regulating signaling path-ways,participating in cellular transmission pathways,competitively binding of miRNA,and changing the protein structure or functional status.This article will provide a comprehensive review of the regulatory effects and mechanism of lncRNA CASC2 on chemotherapy resistance in malignant tumors.