Glioma, the most common malignant tumor of the adult central nervous system, has a high mortality rate. The combination of temozolomide (TMZ) chemotherapy and radiotherapy is the current standard for curing gliomas, but most patients eventually develop resistance to TMZ as time elapses. The prognosis of Glioma patients remains within a mean survival of only 12-15 months. A large body of evidence indicates the high prevalence of TMZ resistance is an important cause of glioma treatment failure in the population. Therefore, to better individualize and precision therapy, finding new molecular targets that increase TM therapeutic sensitivity and enhance the effectiveness of therapy is of great significance for glioma treatment and improving patient survival.

The gene p53 and DNA-damage regulated 1 (PDRG1) was first cloned in 2003 as a small molecule that affects the cellular response to genotoxic stress. An increasing number of studies have confirmed PDRG1 as a tumor marker; the expression of PDRG1 is elevated in a variety of tumor tissues, such as colorectal, ovarian, lung, breast, and endometrial cancers. Studies reveal that the patient TNM stage increases as the expression of PDRG1 in esophageal cancer tissues elevate. PDRG1 knockdown in esophageal cancer tissues inhibits esophageal cancer cells, promotes apoptosis, and reduces cisplatin resistance. Other research showed that PDRG1 is related to the radiotherapy sensitivity of lung cancer cells or nasopharyngeal carcinoma cells. PDRG1 expression has been reported to be significantly higher in glioma cells than in adjacent brain tissues.

T98G and U118 cells were selected. The drug concentration of starting TMZ was set with IC50 of each cell line, the medium containing TMZ was changed every two days, and the same concentration of TMZ was maintained for two weeks. The new IC50 was calculated, the TMZ concentration was increased, and the solution was changed in the same way for another two weeks. This was repeated until IC50 was increased to 500uM. After the successful preparation of TMZ-resistant cells, the culture was maintained at a low concentration of TM billion (different cell concentrations were different). Cell lines were expanded and preserved after establishment.

We applied public database and bioinformatics to screen for genes involved in glioma TMZ resistance and analyzed their biological properties. Moreover, we analyzed the expression of PDRG1 in glioma tissues of different disease response states in patients after treatment with TM and found that PDRG1 expression was significantly higher in gliomas with progressive disease than in those with complete response glioma. In addition, we further analyze and found that PDRG1 was closely related to multidrug resistance as well as DNA damage repair, homologous recombination repair, and other pathways. The activation of the DNA damage repair mechanism is an important factor affecting the outcome of chemotherapy or radiotherapy in most tumors. The results suggest that PDRG1 played an important role in TMZ resistance to glioma.

We knocked down PDRG1 expression in glioma cells, established a stable PDRG1 knockdown cell line, and explored the effect of PDGR1 on glioma TMZ resistance. We tested its resistance to TMZ and the expression level of PDRG1 protein. The results of this study provide a basis for clinical research on TMZ-resistant glioma cell lines and provide a potential molecular drug target to reverse TMZ resistance.

1. Successfully construct TMZ-resistance T98G and U118 cell lines.
2. Screen for TMZ resistance-related genes through a bioinformatics way.
3. Transfect the constructed TMZ-resistance cell line with lentivirus to knock down the target gene.
4. measure the expression level of PDRG1 protein and the transfected cell lines’ resistance of TMZ.

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