Chromosomal localization of the gene for a human cytosolic thyroid hormone binding protein homologous to the subunit of pyruvate kinase, subtype M2

Small in Size, but Large in Action: microRNAs as Potential Modulators of PTEN in Breast and Lung Cancers

MicroRNAs (miRNAs) are well-known regulators of biological mechanisms with a small size of 19–24 nucleotides and a single-stranded structure. miRNA dysregulation occurs in cancer progression. miRNAs can function as tumor-suppressing or tumor-promoting factors in cancer via regulating molecular pathways. Breast and lung cancers are two malignant thoracic tumors in which the abnormal expression of miRNAs plays a significant role in their development. Phosphatase and tensin homolog (PTEN) is a tumor-suppressor factor that is capable of suppressing the growth, viability, and metastasis of cancer cells via downregulating phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt) signaling. PTEN downregulation occurs in lung and breast cancers to promote PI3K/Akt expression, leading to uncontrolled proliferation, metastasis, and their resistance to chemotherapy and radiotherapy. miRNAs as upstream mediators of PTEN can dually induce/inhibit PTEN signaling in affecting the malignant behavior of lung and breast cancer cells. Furthermore, long non-coding RNAs and circular RNAs can regulate the miRNA/PTEN axis in lung and breast cancer cells. It seems that anti-tumor compounds such as baicalein, propofol, and curcumin can induce PTEN upregulation by affecting miRNAs in suppressing breast and lung cancer progression. These topics are discussed in the current review with a focus on molecular pathways.

Deoxyshikonin Inhibits Viability and Glycolysis by Suppressing the Akt/mTOR Pathway in Acute Myeloid Leukemia Cells

Deoxyshikonin was reported to exhibit an anti-tumor effect in colorectal cancer. However, no studies are available to illustrate the effect of deoxyshikonin on acute myeloid leukemia (AML). The effects of deoxyshikonin on viability, apoptosis, caspase-3/7 activity, and cytochrome (Cyt) C expression were evaluated by Cell Counting Kit-8 assay, flow cytometry analysis, caspase-3/7 activity assay, and western blot analysis, respectively. Glucose consumption and lactate production were measured to determine the glycolysis level. The expression of pyruvate kinase M2 (PKM2) was detected by quantitative real-time polymerase chain reaction and western blot analysis. The results showed that deoxyshikonin inhibited cell viability and increased the apoptotic rate, the caspase-3/7 activity, and the Cyt C protein level in AML cells in a dose-dependent manner. Additionally, deoxyshikonin concentration-dependently decreased glucose consumption, lactate production, and PKM2 expression in AML cells. Deoxyshikonin inactivated the protein kinase B (Akt)/mammalian target of the rapamycin (mTOR) pathway. The activation of the Akt/mTOR pathway reversed the effects of deoxyshikonin on viability, apoptosis, and glycolysis in AML cells. In conclusion, deoxyshikonin dampened the viability and the glycolysis of AML cells by suppressing PKM2 via inactivation of the Akt/mTOR signaling.

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.