[Inhibitory effect of ketogenic diet on neuroblastoma in BALB/c-nu mouse models].

OBJECTIVE: To investigate the inhibitory effect of ketogenic diet (KD) on growth of neuroblastoma in mice. METHODS: BALB/c-nu mouse models bearing neuroblastoma xenografts were established by subcutaneous injection of human neuroblastoma cell line (SH-SY5Y). When the tumor volume reached 250 mm3, the mice were randomized into SD group with standard diet and PBS treatment, KD group with ketogenic diet and PBS treatment, and CP+KD group with ketogenic diet and cyclophosphamide (60 mg·kg-1·day-1) treatment, n=8. The tumor volume, body weight, blood glucose, ketone body (ß-Hydroxybutyrate) levels, and hepatic steatosis in the mice were assessed. The expressions of caspase-3 and caspase-8 were detected by Western blotting, and Ki67 expresison was detected using immunohistochemistry (IHC). Transmission electron microscopy (TEM) was employed for the autophagosomes, and the autophagic protein Beclin1, LC3A/B and P62 were detected by IHC and Western blotting. RESULTS: On day 28 post tumor cell injection, the mice in KD and CP+KD groups could prolong the overall survival rates than that in SD group (P < 0.001). On day 22 post the injection, the tumor volume in KD group was smaller than that in SD group (P < 0.05); on 16, 19, and 22 day post the injection, the tumor volume in CP+KD group was smaller than that in SD group (P < 0.01). The mice in SD group showed greater body weight on day 19 and higher blood glucose level on day 13 post the injection than those in the other two groups (P < 0.05). Blood ketone level and hepatic steatosis score were higher and glucose ketone index (GKI) was lower in KD and CP+KD groups than those in SD group (all P < 0.05). The expressions of Ki67 and apoptotic proteins were detected in the tumor tissues of all groups. TEM revealed more autophagosomes in the tumor tissues of KD group than that of SD group. P62 expression was lowered (P < 0.01) and Beclin1 and LC3A/B expressions were up-regulated in the tumor tissues of KD group (P < 0.05), which is consisitent with IHC. CONCLUSIONS: KD has a strong anti-tumor effect in the xenograft mouse model possibly by regulating cell autophagy.

MiR99a modulates MMP7 and MMP13 to regulate invasiveness of Kaposi's sarcoma.

Matrix metalloproteinases (MMPs) and microRNAs (miRNAs) are associated with Kaposi's sarcoma (KS) tumorigenesis. To date, the molecular basis underlying crosstalk of MMPs and miRNAs in KS remains unexplored. From the resected KS samples, we detected significant correlation of miRNA99a (miR99a), with MMP7 and MMP13, but not with MMP9. To define whether a causal link exists, we used a human KS line, SLK, to study the molecular basis of miR99a and activation of MMP7, MMP9, and MMP13. We found that overexpression of miR99a in SLK cells decreased MMP7 and MMP13, but not MMP9. Similarly, MiR99a inhibition in SLK cells activated MMP7 and MMP13, but did not affect expression of MMP9. These data suggest that MMP7 and MMP13 seem to be regulated by miR99a, while MMP9 seems to be regulated in a miR99a-independent manner. Inhibition of PI3k/Akt signaling pathway significantly abolished the effect of miR99a-knockdown on MMP7, but not MMP13 activation, while inhibition of ERK/MAPK signaling pathway significantly abolished the effect of miR99a-knockdown on MMP13, but not MMP7 activation. Taken together, our data suggest that miR99a inhibits MMP7 and MMP13 through PI3k/Akt and ERK/MAPK signaling pathway, respectively, in KS. Thus, miR99a, MMP7, and MMP13 appear to be promising therapeutic targets for preventing the metastasis of KS.