Exosomes Serve as Nanoparticles to Deliver Anti-miR-214 to Reverse Chemoresistance to Cisplatin in Gastric Cancer

Clinical significance of exosomal miRNAs and proteins in three human cancers with high mortality in China

Cancer is the second leading cause of mortality worldwide. More importantly, the mortality rates for cancer are increasing. In China, lung cancer, liver cancer and gastric cancer are the top three leading causes of mortality in males, whereas lung cancer, gastric cancer and liver cancer are ranked the top three causes of mortality in females. Exosomes are extracellular vesicles that are produced and released by many different cells; these vesicles have a size range between 30 and 100 nm in diameter, and contain a lipid bilayer. Exosomes exist in various bodily fluids, contain plentiful amounts of nucleic acids and proteins, and shuttle these materials between cells to mediate the development of cancers. The present review summarizes the composition of exosomes and methods for their isolation and then intensively highlights the latest findings on the contributions of exosomal microRNAs (miRNAs) and proteins to lung cancer, liver cancer and gastric cancer. Taken together, exosomal miRNAs and proteins may be used as noninvasive, novel biomarkers for cancer diagnosis, prognosis or precision treatment owing to their ability to promote tumor progression and metastasis, and their ability to regulate the immune response and tumor cell sensitivity to chemotherapy drugs.

Exosomes in cancer: Small transporters with big functions

Exosomes are nanosized membrane-bound vesicles containing abundant proteins, DNA, mRNA, and non-coding RNAs. Exosomes are now considered as an additional mechanism for intercellular communication, allowing cells to exchange proteins, lipids and genetic material. Increasing studies have shown that exosomes play an important role in tumour initiation, growth, progression, metastasis, drug resistance and immune escape. In this article, we review recent advances in the biology of exosomes. We elaborate the specific mechanism by which exosomes affect the communication between tumours and the microenvironment. Finally, we report that exosomes may provide promising biomarkers for cancer diagnosis and represent new targets for cancer therapy.

Down-regulation of miR-214 inhibits proliferation and glycolysis in non-small-cell lung cancer cells via down-regulating the expression of hexokinase 2 and pyruvate kinase isozyme M2

Glycolysis is a metabolic pathway that is enhanced in cancer cells. miR-214 plays an important role in cancer development and can modulate glycolysis. However, whether miR-214 can regulate glycolysis in non-small-cell lung cancer (NSCLC) cells has not yet been investigated. The expression levels of miR-214 in 7 NSCLC cell lines were measured by qRT-PCR. MTT assay was performed to evaluate the cell proliferation. Glucose consumption and lactate production were measured to assess the level of glycolysis. The expression of hexokinase 2 (HK2) and pyruvate kinase isozyme M2 (PKM2) was measured by qRT-PCR and western blot analysis. Luciferase reporter assay was carried out to confirm the target gene of miR-214. The levels of PTEN, p-Akt, Akt, p-mTOR, mTOR, p-S6K, and S6K were assessed by western blot analysis. Results showed that miR-214 levels were significantly increased in the 7 NSCLC cell lines compared with those in the human bronchial epithelial cell line. Down-regulation of miR-214 inhibited cell proliferation, glucose consumption, lactate production, and expression of HK2 and PKM2 in NSCLC cells. We also confirmed that miR-214 directly targeted PTEN and regulated the PTEN/Akt/mTOR pathway. Inhibition of the PTEN/Akt/mTOR pathway attenuated the effect of miR-214 mimics on glucose consumption, lactate production, and expression of HK2 and PKM2 in NSCLC cells. These results demonstrated that miR-214 down-regulation inhibited cell proliferation and glycolysis by down-regulating the expression of HK2 and PKM2 via the PTEN/Akt/mTOR pathway in NSCLC cells. Hence, our findings suggested that miR-214 might serve as a novel therapeutic target for NSCLC.