RESUMO
PURPOSE: Biological effects of low-dose radiation (LDR) are distinguishable from those of high-dose radiation. Adaptive response is an important biological effect following low-dose radiation. Cancer stem cells (CSCs) have self-renewal and multidirectional differentiation potency which results in relapse and metastasis of cancer. In this study, we aimed to examine whether adaptive response could be induced in CSCs by LDR. METHODS: Parental cells of three colon cancer cell lines (HRT18, HT29, and HCT116) and CSCs of these three cell lines were irradiated with LDR (i.e., D1) and then high-dose radiation (HDR) of X-rays (i.e., D1 + D2) or only HDR (D2 alone), followed by examination of adaptive response. RESULTS: Adaptive response was not observed either in the three tumor parental cells lines or in three CSCs lines following LDR, due to the lack of resistance to subsequent D2-induced cell growth inhibition. CONCLUSION: These results suggested that LDR may not induce adaptive response in colon cancer cells or colon CSCs under in vitro conditions. Our study provided experimental and clinical foundations for the application of LDR in the treatment of colon cancers.
Assuntos
Sobrevivência Celular/efeitos da radiação , Neoplasias do Colo/patologia , Células-Tronco Neoplásicas/patologia , Tolerância a Radiação , Neoplasias do Colo/radioterapia , Relação Dose-Resposta à Radiação , Humanos , Células-Tronco Neoplásicas/efeitos da radiação , Células Tumorais Cultivadas , Raios XRESUMO
We investigated local changes in BMP-2/4 expression in rat spinal cords 1 week following injury to study the damage effects of BMP-2/4 in spinal cord injury (SCI). Sprague Dawley rats (45, 4 months old) were randomized into three groups comprising 15 rats each: a SHAM group, an SCI without noggin group (SCIO), and an SCI with noggin group (SCID). The SCIO and SCID groups were subjected to spinal cord hemisection, and motor activity was assessed using the BBB score. Expression of BMP-2/4 in each injured spinal cord section was examined by hematoxylin and eosin staining, immunohistochemistry, and western blot. There were no significant differences in BBB scores among the three groups (P > 0.05). Following hemisection, the BBB score in the SHAM group was significantly higher than in the other two groups on the 1st day after modeling (P < 0.05), and the BBB scores in the SCIO and SCID groups were not significantly different (P > 0.05). Seven days after modeling, the BBB score in the SHAM group was significantly higher than in the other two groups (P < 0.05), and the BBB score in the SCID group was obviously higher than in the SCIO group (P < 0.05). The expression of BMP-2/4 was highest in the SCIO group and lowest in the SHAM group (P < 0.05). SCI can cause severe impairment of motor activity in rats. Seven days after SCI, the local expression of BMP-2/4 had obviously increased; noggin can effectively inhibit the expression of BMP-2/4 and reduce impairment.