ABSTRACT
Objective: DEP domain containing 1 (DEPDC1), aberrantly upregulated in various tumors, has been shown to be involved in the occurrence and development of tumors. This study aims to investigate pathophysiological roles of DEPDC1 in colorectal cancer (CRC). Materials and Methods: Expression level of DEPDC1 and suppressor of zest 12 (SUZ12) in CRC tissues and cell lines were analyzed by quantitative real-time polymerase chain reaction and immunohistochemistry. Staining with 5-bromo-2-deoxyuridine staining and colony formation assays were conducted to evaluate cell proliferation. Transwell or wound healing assay to evaluate invasion or migration, respectively. The effect on epithelial-mesenchymal transition (EMT) of CRC was determined by Western blot. Results: DEPDC1 and SUZ12 were increased in CRC tissues and cell lines. Silence of DEPDC1 suppressed cell proliferation, migration, and invasion of CRC. Moreover, DEPDC1 knockdown suppressed EMT of CRC. Mechanistically, the authors demonstrated silencing DEPDC1 decreased protein expression of SUZ12 and led to a remarkable reduction of trimethylation on the lysine 27 residue of histone H3 (H3K27Me3). Inhibitory ability of DEPDC1 knockdown on CRC progression was reversed by overexpression of SUZ12. Conclusions: DEPDC1 promoted CRC progression through regulation of SUZ12-mediated H3K27Me3, illuminating a novel DEPDC1-SUZ12 molecular axis as regulator in CRC progression and suggesting potential implications in treatment of CRC.
Subject(s)
Colorectal Neoplasms/genetics , GTPase-Activating Proteins/metabolism , Gene Expression Regulation, Neoplastic , Neoplasm Proteins/genetics , Neoplasm Proteins/metabolism , Transcription Factors/genetics , Apoptosis/genetics , Cell Line, Tumor , Cell Movement/genetics , Cell Proliferation/genetics , Colorectal Neoplasms/pathology , Colorectal Neoplasms/surgery , Epithelial-Mesenchymal Transition/genetics , Female , GTPase-Activating Proteins/genetics , Gene Knockdown Techniques , Histones/metabolism , Humans , Male , Methylation , Middle Aged , Neoplasm Invasiveness/genetics , Up-RegulationABSTRACT
Reactive oxygen species (ROS) have emerged as important signaling molecules that play crucial roles in carcinogenesis and cytotoxic responses. Nrf2 is the master regulator of ROS balance. Thus, uncovering mechanisms of Nrf2 regulation is important for the development of alternative treatment strategies for cancers. Here, we demonstrate that iASPP, a known p53 inhibitor, lowers ROS independently of p53. Mechanistically, iASPP competes with Nrf2 for Keap1 binding via a DLT motif, leading to decreased Nrf2 ubiquitination and increased Nrf2 accumulation, nuclear translocation, and antioxidative transactivation. This iASPP-Keap1-Nrf2 axis promotes cancer growth and drug resistance both in vitro and in vivo. Thus, iASPP is an antioxidative factor and represents a promising target to improve cancer treatment, regardless of p53 status.
Subject(s)
Cell Proliferation , Drug Resistance, Neoplasm , Intracellular Signaling Peptides and Proteins/metabolism , Kelch-Like ECH-Associated Protein 1/metabolism , NF-E2-Related Factor 2/metabolism , Repressor Proteins/metabolism , Antioxidants/metabolism , Blotting, Western , Cell Line, Tumor , HCT116 Cells , Humans , Intracellular Signaling Peptides and Proteins/genetics , Kelch-Like ECH-Associated Protein 1/genetics , NF-E2-Related Factor 2/genetics , Neoplasms/genetics , Neoplasms/metabolism , Neoplasms/pathology , Protein Binding , RNA Interference , Reactive Oxygen Species/metabolism , Repressor Proteins/genetics , Tumor Suppressor Protein p53/genetics , Tumor Suppressor Protein p53/metabolismABSTRACT
Inactivation of p53 has been shown to correlate with drug resistance in tumors. However, in clear cell renal cell carcinoma (ccRCC), p53 is rarely mutated, yet the tumors remain highly insensitive to the conventional chemotherapeutic drugs. The underlying mechanisms responsible for the non-genetic p53 inactivation remain obscure. Here, we report, for the first time, that Apoptosis Stimulating of P53 Protein 1 (ASPP1) was remarkably downregulated at both mRNA (about 3.9-fold) and protein (about 4.9-fold) levels in ccRCC human specimens in comparison with the paired normal controls. In addition, lower ASPP1 was closely related to the higher grade of tumors and shorter life expectancy of ccRCC patients, both with p < 0.001. We also find that CpG island hypermethylation at promoter region contributed to the suppression of ASPP1 expression in ccRCC that contained relatively low levels of ASPP1. Further functional studies demonstrated that forced expression ASPP1 not only significantly inhibited the growth rate of ccRCC, but also promoted sensitivity of ccRCC to the conventional chemotherapeutic drug 5-fluorouracil (5-FU)-induced apoptosis. Moreover, ASPP1 expression was accompanied with the apoptosis-prone alterations of p53 targets expression and p53 target PIG3 luciferase reporter activation. In contrast, ASPP1 knockdown promoted cell growth and prevent 5-FU-induced p53 activation and apoptosis. In conclusion, our results suggest that ASPP1 silencing is one of dominate mechanisms in inhibiting wild type p53 in ccRCC. ASPP1, therefore, may be potentially used as a promising biomarker for prognosis and therapeutic intervention in ccRCC.
Subject(s)
Adaptor Proteins, Signal Transducing/metabolism , Apoptosis Regulatory Proteins/metabolism , Carcinoma, Renal Cell/drug therapy , Carcinoma, Renal Cell/metabolism , CpG Islands , Drug Resistance, Neoplasm , Kidney Neoplasms/drug therapy , Kidney Neoplasms/metabolism , Neoplasm Proteins/metabolism , Adaptor Proteins, Signal Transducing/genetics , Animals , Antimetabolites, Antineoplastic/pharmacology , Apoptosis , Apoptosis Regulatory Proteins/genetics , Carcinoma, Renal Cell/genetics , Carcinoma, Renal Cell/mortality , Cell Line, Tumor , DNA Methylation , Down-Regulation , Epigenesis, Genetic , Female , Fluorouracil/pharmacology , Gene Silencing , Genes, p53 , Humans , Kidney/metabolism , Kidney Neoplasms/genetics , Kidney Neoplasms/mortality , Male , Mice , Mice, Nude , Middle Aged , Neoplasm Proteins/genetics , Promoter Regions, Genetic , RNA, Messenger/metabolism , Transcriptional Activation , Transplantation, HeterologousABSTRACT
OBJECTIVE: The aim of the present study was to examine the apoptosis-promoting effects and mechanisms of hematoporphyrin monomethyl ether (HMME)-sonodynamic therapy (SDT) on endometrial cancer cells in vitro. METHODS: Endometrial cancer cell samples were divided into four groups: 1) untreated control group, 2) HMME group, 3) pure ultrasound group, and 4) HMME combined with ultrasound, i.e. SDT group. CCK-8 method was utilized to assess the inhibiting effect of SDT on the proliferation of endometrial cancer cells. Optical microscope and field emission transmission electron microscopy were used to characterize the morphology changes of the cancer cells induced by the treatments. Apoptosis rate, reactive oxygen species (ROS) and mitochondrial membrane potential (MMP) were examined by flow cytometer. Fluorescence intensity measured by laser scanning confocal microscopy was used to explore the variation of intracellular calcium ion (Ca2+) concentration. Apoptosis-related proteins involved in both intrinsic and extrinsic apoptosis signallings were analyzed by western blot. RESULTS: SDT can effectively induce the apoptosis of endometrial cancer cells. Compared with ultrasound which is known as an effective anti-tumor method, SDT leads to a significant improvement on suppression of cell viability and induction of apoptosis, together with more remarkable modifications on the morphology and substructure in both ultrasound sensitive and resistant endometrial cancer cells. Further studies reveals that SDT promotes ROS production, induces loss of MMP and increases intracellular Ca2+ concentration more efficiently than HMME or ultrasound alone. SDT groups also show a rather high expression of apoptosis-promoting proteins, including Bax, Fas and Fas-L, and a significant low expression of apoptosis-suspending proteins including Bcl-2 and Survivin. Meanwhile, both cleaved caspse-3 and caspase-8 are dramatically enhanced in SDT groups. Multiple pathways has been proposed in the process, including the intrinsic activation by excessive ROS and overloaded Ca2+, silencing survivin gene, and the extrinsic pathway mediated by the death receptor. CONCLUSION: Given its considerable effectivity in both ultrasound sensitive and resistant cells, SDT may therefore be a promising therapeutic method for treating endometrial cancers.