Relationship Of FA Pathway Dysfunction And Cisplatin Sensitivity In Non-small-cell Lung Cancer

BackgroundLung cancer has been the most important dead reason of all cancers in the world. About 31% of cancer related death is caused by lung cancer. The 5 year survival rate of lung cancer is about 15%. The low survival rate of lung cancer is mainly caused the late diagnosis based on symptom. 3/4 of the patients have metastasis tumor when diagnosed. If the lung cancer patients can be diagnosed in early stage, the 5 year survival rate can raised to 60-80%.Till today the chemotherapy of lung cancer is based on platins. The main reason of treatment failure is resistance of chemotherapy drugs, especially in recurrence tumor. Excision repair cross complementing 1(ERCC1) expression is found to have a close relationship to platinum resistance.Fanconi Anemia is a genetic disease characterized by malformation, anemia and easier to develop tumor. To date 15 variance genes were found in FA patients , the 15 genes composed the FA-BRCA pathway, which also is called FA pathway.. The super high incidence of cancer in FA patients revealed that the FA pathway is a tumor restriction pathway. FA pathway is found to related to S-phase homologous recombination and cell cycle checkpoint. Dysfunction of FA pathway will cause the lower ability of DNA repair, this rendered the high incidence of tumor and the high sensitivity to drugs which impact the DNA interaction. Experiments have found that ERCC1 is involved in FA pathway function and can activate FA pathway. When the ERCC1 is blocked by gene knock out, the FA pathway function will be discounted. Another experiment found that when destroy the FA pathway function by Sodium Phenylbutyrate, the head and neck cancer cells will be sensitive to cisplatin again. We expected to use Sodium Phenylbutyrate to destroy the FA pathway of NSCLC cells and this maybe will make NSCLC cells more sensitive to cisplatin. The idea may find a new way to settle the drug resistance problems of cisplatin. Object:To observe the FA pathway dysfunction expression rate in Non-small Cell Lung Cancer. Find out whether FA pathway dysfunction could make NSCLC cells more sensitive to Cisplatin, and whether Sodium Phenylbutyrate could change the sensitivity to Cisplatin in NSCLC cells.Materials and methods:50 NSCLC tissue samples after Cisplatin chemotherapy were collected, and the FANCD2 ubiquitination level was tested by immunohistochemistry. We also tested the FANCD2 ubiquitination level by Western-blotting in 10 NSCLC cell lines after Cisplatin treatment. Karyotype assay was used to observe the chromosome breakage in cell line A549 and Ht182.To observe the sensitivity to Cisplatin and Sodium Phenylbutyrate, cell survival assay were used in cell line A549, UMC11 and Ht182. And colongenic assay were selected to observe the ability of colony formation in the same three cell lines.Results:Among 50 NSCLC tissue samples, 14(28.0%) were found to have no FANCD2 ubiquitination expression. This means FA pathway dysfunction occurred in those 14 NSCLC tissues. The FA pathway dysfunction is related to the differentiation(P=0.003), but has no relationship to age, sex, P-TNM and histology. The FANCD2 ubiquitination level was obviously lower in 4 cell lines among 10. Karyotype assay shows that the chromosome breakage rate is much higher in the FA pathway dysfunction Ht182 cells(44.74%) than that in A549 cells(2.27%), which has a normal FA pathway(P<0.005).Cell survival assay showed that 168 hours after Cisplatin treatment, the survival rates of Ht182 and UMC11 were much lower than that of A549, the P level were 0.027 and 0.016 seperately. Controlled with NS, Sodium Phenylbutyrate did not change the survival rate in three NSCLC cell lines. Sodium Phenylbutyrate maked the A549 cells more sensitive to Cisplatin(P=0.036),but the same phenomenon was not seen in Ht182 and UMC11 cells.Conclusion:FA pathway dysfunction expresses in part of NSCLC cells, the expression rate is associated with poorly differentiated NSCLC cells. FA pathway dysfunction makes the NSCLC cells more sensitive to cisplatin. Sodium Phenylbutyrate can improve the sensitivity to cisplatin in NSCLC cells which have a normal FA pathway.