In previous studies, lactate dehydrogenase A (LDHA) was identified as one of the leading genes that promote the proliferative and tumorigenic potential of malignancies. However, less definitive evidence was reported in hepatocellular carcinoma (HCC) cells. Furthermore, the role of LDHA in promoting metastasis of HCC, and its possible mechanism, is not clear. In this study, RNA interference (RNAi) mediated by lentiviral vectors (which induce strong down‐regulation of gene expression) was used to analyze the role of LDHA in tumor growth and metastasis in HCC. We performed transient and stable RNAi knockdowns of LDHA in HCCLM3 cells, a line that over‐expresses LDHA and has a high metastatic potential. Our studies reveal that previously unidentified effects of LHDA may mediate tumor growth and metastasic effects in HCC. First, HCC cell lines over‐express LDHA. Second, LDHA inhibition results in increased apoptosis via production of reactive oxygen species in HCCLM3 cells. Thus, LDHA knockdown resulted in significant reduction in metastatic potential in a xenograft mouse model. Furthermore, we found that FAK, MMP–2, VEGF and E–cadherin proteins contribute to inhibitory effects on metastasis in HCC cells. These studies have important implications for understanding the mechanisms by which LDHA promotes tumor growth and metastasis.

Background: Colon cancer is the second leading cancer worldwide. Recurrent disease and chemotherapeutic drug resistance are very common in the advanced stage of colon cancer. ATP-citrate lyase (ACLY), the first-step rate-controlling enzyme in lipid synthesis, is elevated in colon cancer. However, it remains unclear about the exact role of ACLY in the development of colon cancer metastasis. Methods: To evaluate the role of ACLY in colon cancer metastasis, we performed cell migration and invasion assays in two ACLY-deficient colon cancer cell lines. Colon cancer mouse model is used to examine ACLY’s effects on colon metastasis potentials in vivo. We analyzed the correlation between ACLY and CTNNB1 protein in 78 colon cancer patients by Pearson correlation. To finally explore the relationship of ACLY and CTNNB1, we used western blots, migration and invasion assays to confirm that ACLY may regulate metastasis by CTNNB1. Results: Our data showed that the abilities of cell migration and invasion were attenuated in ACLY-deficient HCT116 and RKO cell lines. Furthermore, we describe the mechanism of ACLY in promoting colon cancer metastasis in vitro and in vivo. ACLY could stabilize CTNNB1 (beta-catenin 1) protein by interacting, and the complex might promote CTNNB1 translocation through cytoplasm to nucleus, subsequently promote the CTNNB1 transcriptional activity and migration and invasion abilities of colon cancer cells. Immunohistochemical analysis of 78 colon cancer patients showed that the high expression levels of ACLY and CTNNB1 protein was positively correlated with metastasis of colon cancer. Conclusions: These results shed new light on the molecular mechanism underlying colon cancer metastasis, which might help in improving therapeutic efficacy.

MiR-22 inhibits tumor growth and metastasis by targeting ATP citrate lyase: evidence in osteosarcoma, prostate cancer, cervical cancer and lung cancer

SIRT6 is an important histone modifying protein that regulates DNA repair, telomere maintenance, energy metabolism, and target gene expression. Recently SIRT6 has been identified as a tumor suppressor and is down-regulated in certain cancer types, but not in other cancers. From deposited gene profiling studies we found that SIRT6 was overexpressed in prostate tumors, compared with normal or paratumor prostate tissues. Tissue micro-array studies confirmed the higher levels of SIRT6 in both prostate tumor tissues and prostate cancer cells than in their normal counterparts. Knockdown of SIRT6 in human prostate cancer cells led to sub-G₁ phase arrest of cell cycle, increased apoptosis, elevated DNA damage level and decrease in BCL2 gene expression. Moreover, SIRT6-de-ficiency reduced cell viability and enhanced chemotherapeutics sensitivity. Taken together, this study provides the first evidence of SIRT6 overexpression in human prostate cancer, and SIRT6 regulation could be exploited for prostate cancer therapy.