RESUMEN
Resistance to radiotherapy is frequently encountered in clinic, leading to poor prognosis of cancer patients. Long noncoding RNAs (lncRNAs) play important roles in the development of radioresistance due to their functions in regulating the expression of target genes at both transcriptional and posttranscriptional levels. Exploring key lncRNAs and elucidating the mechanisms contributing to radioresistance are crucial for the development of effective strategies to reverse radioresistance, which however remains challenging. Here, actin filament-associated protein 1 antisense RNA1 (lncAFAP1-AS1) is identified as a key factor in inducing radioresistance of triple-negative breast cancer (TNBC) via activating the Wnt/ß-catenin signaling pathway. Considering the generation of a high concentration of reduction agent glutathione (GSH) under radiation, a reduction-responsive nanoparticle (NP) platform is engineered for effective lncAFAP1-AS1 siRNA (siAFAP1-AS1) delivery. Systemic delivery of siAFAP1-AS1 with the reduction-responsive NPs can synergistically reverse radioresistance by silencing lncAFAP1-AS1 expression and scavenging intracellular GSH, leading to a dramatically enhanced radiotherapy effect in both xenograft and metastatic TNBC tumor models. The findings indicate that lncAFAP1-AS1 can be used to predict the outcome of TNBC radiotherapy and combination of systemic siAFAP1-AS1 delivery with radiotherapy can be applied for the treatment of recurrent TNBC patients.
RESUMEN
OBJECTIVE: The purpose of this study was to investigate the value of postoperative chemotherapy for locally advanced rectal cancer patients who reached pathological ypT1-4N0 after neo-adjuvant chemoradiotherapy. METHODS: We performed a retrospective study of 104 patients treated with preoperative chemoradiotherapy followed by radical resection, who achieved pathological ypT1-4N0, between Mar 2003 and Dec 2010. There were 73 patients who received postoperative adjuvant chemotherapy, and the other 31 patients did not. The distribution of final pathologic stages for these patients was ypT1-2N0 in 39 cases and ypT3-4N0 in 65 cases. RESULTS: The median follow-up was 41 months. The 3-year overall survival rate (OS) and recurrence-free survival rate (RFS) for the whole group (ypT1-4N0) were 93.4% and 85.3%, respectively. The 3-year OS and RFS in the adjuvant chemotherapy group and non-adjuvant chemotherapy group were 95.5%, 88.6% and 88.6%, 77.2%, respectively. There were no significant differences in 3-year RFS (P = 0.108) and OS (P = 0.106) between the two groups. The 3-year local recurrence and distant metastasis rates in the adjuvant chemotherapy group were 4.1% (3/73) and 5.5% (4/73), while for the non-adjuvant chemotherapy group, the 3-year local recurrence rate and distant metastasis rate were 3.2% (1/31) and 16.1% (5/31), respectively. Significant difference was found in distant metastasis rates (P = 0.030) between the two groups, but not in local recurrence rates (P = 0.676).Further subgroup analysis indicated that for the ypT1-2N0 patients, there were no significant differences in 3-year OS (P = 0.296) and RFS (P = 0.939) between the adjuvant and non-adjuvant chemotherapy groups, while negative results displayed in 3-year local recurrence rates (P = 0.676) and distant metastasis rates (P = 0.414). However, for patients with ypT3-4N0, significant differences were showed in both the 3-year OS (P = 0.034) and RFS (P = 0.025), and further analysis revealed that the 3-year distant metastasis rate was significantly higher in the non-adjuvant chemotherapy group than in the adjuvant chemotherapy group (P = 0.010) , but with non-significant difference in the 3-year local recurrence (P = 0.548). CONCLUSIONS: Adjuvant chemotherapy may not improve survival for ypT1-2N0 patients. However, it may be clinically meaningful for ypT3-4N0 patients by decreasing distant metastasis rate. Further randomized controlled clinical trials are needed to confirm our results.