RESUMO
BACKGROUND: Hepatocellular carcinoma (HCC) has an increasing incidence and high mortality. Surgical operation is not a comprehensive strategy for liver cancer. Moreover, tolerating systemic chemotherapy is difficult for patients with HCC because hepatic function is often impaired due to underlying cirrhosis. Therefore, a comprehensive strategy for cancer treatment should be developed. DTL (Cdc10-dependent transcript 2) is a critical regulator of cell cycle progression and genomic stability. In our previous study, the upregulation of DTL expression in aggressive HCC correlated positively with tumor grade and poor patient survival. We hypothesize that targeting DTL may provide a novel therapeutic strategy for liver cancer. DTL small interference RNAs were used to knock down DTL protein expression. METHODS: A clonogenic assay, immunostaining, double thymidine block, imaging flow cytometry analysis, and a tumor spheroid formation assay were used to analyze the role of DTL in tumor cell growth, cell cycle progression, micronucleation, ploidy, and tumorigenicity. RESULTS: Our results demonstrated that targeting DTL reduced cell cycle regulators and chromosome segregation genes, resulting in increased cell micronucleation. DTL depletion inhibited liver cancer cell growth, increased senescence, and reduced tumorigenesis. DTL depletion resulted in the disruption of the mitotic proteins cyclin B, CDK1, securin, seprase, Aurora A, and Aurora B as well as the upregulation of the cell cycle arrest gene p21. A rescue assay indicated that DTL should be targeted through TPX2 downregulation for cancer cell growth inhibition. Moreover, DTL silencing inhibited the growth of patient-derived primary cultured HCC cells. CONCLUSION: Our study results indicate that DTL is a potential novel target gene for treating liver cancer through liver cancer cell senescence induction. Furthermore, our results provide insights into molecular mechanisms for targeting DTL in liver cancer cells. The results also indicate several other starting points for future preclinical and clinical studies on liver cancer treatment.
RESUMO
Prostate cancer is a complex disease that can be relatively harmless or extremely aggressive. Although androgen-deprivation therapy is a commonly used treatment for men with prostate cancer, the adverse effects can be detrimental to patient health and quality of life. Therefore, identifying new target genes for tumor growth will enable the development of novel therapeutic intervention. TPX2 plays a critical role in chromosome segregation machinery during mitosis. Low rates of chromosome missegregation can promote tumor development, whereas higher levels might promote cell death and suppress tumorigenesis. Hence, the strategy of promoting cell death by inducing massive chromosome missegregation has been a therapeutic application for selectively eliminating highly proliferating tumor cells. RNAi was used for TPX2 protein expression knockdown, and a clonogenic assay, immunostaining, double thymidine block, image-cytometry analysis, and tumor spheroid assay were used to analyze the role of TPX2 in tumor cell growth, cell cycle progression, multinuclearity, ploidy, and tumorigenicity, respectively; finally, Western blotting was used to analyze anticancer mechanisms in TPX2 targeting. We demonstrated that targeting TPX2 reduced cell cycle regulators and chromosome segregation genes, resulting in increased cell micronucleation. Moreover, TPX2 depletion led to prostate cancer cell growth inhibition, increased apoptosis, and reduced tumorigenesis. These results confirmed the therapeutic potential of targeting TPX2 in prostate cancer treatment. Moreover, we found that TPX2 silencing led to deregulation of CDK1, cyclin B, securin, separase, and aurora A proteins; by contrast, p21 mRNA was upregulated. We also determined the molecular mechanisms for TPX2 targeting in prostate cancer cells. In conclusion, our study illustrates the power of TPX2 as a potential novel target gene for prostate cancer treatment.
RESUMO
Hepatocellular carcinoma (HCC) remains one of the most difficult cancers to treat, with chemotherapies being relatively ineffective. Therefore, a better knowledge of molecular hepatocarcinogenesis will provide opportunities for designing targeted therapies. TPX2 (targeting protein for Xklp2) is overexpressed as a consequence of oncogenic alterations and is likely to alter the proper regulation of chromosome segregation in cancer cells. Disrupting the machinery which is responsible for mitosis and chromosome instability in cancer cells can be one of the most successful strategies for cancer therapy. Therefore, we consider the targeting TPX2 could provide novel therapeutic strategies for cancer. In this study, increased TPX2 protein expression was present in 16 (42%) of 38 primary HCCs and was associated with advanced stage, distant metastatic HCCs and poor prognosis. Knockdown of TPX2 inhibited cancer cell growth and downregulation of cyclin A, cyclin E and CDK2 proteins. However, over-expressed EGFP-TPX2 protein enhanced the in vitro tumor spheroid formation and rescued the TPX2 depleted cell growth. Targeting TPX2 caused a rising impaired chromosomal instability resulting in multinuclearity, cell cycle progression arrest, apotosis, senescence and an increased polyploidy in cells. An image-cytometry analysis revealed cell cycle progression arrest after TPX2 inhibition. A correlation was observed between the downregulation of the protein levels of genes related to chromosomal segregation and spindle assembly checkpoint (securin, seprase, Aurora A, Aurora B, Cyclin B1, Cyclin B2, MPS1, BUB1, BUB3, MAD1 and MAD2) and increased cell ploidy, indicating mitotic progression failure and the loss of the balance of genomic instability. In vitro tumor spheroid assay and in vivo xenografts mouse model showed a therapeutic opportunity. Our findings indicate that targeting TPX2 lead to suppress tumorigenicity in liver cancer cells, suggesting that TPX2 is a potential target for anticancer therapy in HCC.
