The effects of lanthanum chloride on proliferation and apoptosis of cervical cancer cells: involvement of let-7a and miR-34a microRNAs

Lanthanide elements have been documented to possess various biologic effects, and their compounds have been studied intensely for their anti-cancer potential. However, the underlying mechanisms remain largely unknown. In the present study, we propose that the levels of proliferation and apoptosis related microRNAs (miRNAs), let-7a and miR-34a, which mediate the apoptosis of cervical cancer cells, can be affected by the lanthanum ion. Our data showed that LaCl3 inhibited the proliferation and induced the apoptosis of cervical cancer cells both in vivo and in vitro by regulating let-7a, miR-34a and their downstream genes. This study provides novel evidence demonstrating that the anticancer mechanism of lanthanum chloride is partially attributed to miRNAs regulation and establishes an experimental basis for the clinical application of lanthanum chloride as an anti-cancer drug.

MicroRNA-34a suppresses cell proliferation and induces apoptosis in U87 glioma stem cells

Tumor stem cells (TSCs) have been identified in many malignant tumors and are unique in their self-renewal, multi-differentiation and tumor growth maintenance capabilities. MicroRNAs (miRNAs) are small endogenous, non-coding RNAs that predominately modulate target gene expression at the post-transcriptional level. Accumulating evidence suggests that some miRNAs have an essential role in TSC proliferation, growth, apoptosis, and differentiation. In particular, miR-34a has been found to inhibit proliferation and induce apoptosis in stem cells. The insensitivity of glioma to standard therapies combined with the hypothesis that glioma stem cells (GSCs) are responsible for this chemorefractory nature suggests that investigations exploring the function and mechanism of miR-34a in GSCs would be of value. In our study, we found that miR-34a is down-regulated in CD133-positive U87 cells. Furthermore, miR-34a could significantly suppress cell proliferation and induce apoptosis in GSCs. These findings suggest that miR-34a acts as a tumor suppressor in U87 GSCs. Therefore, this observation highlights a new potential therapeutic agent for GSC-based glioma treatment.