Project description:Protein Kinase C alpha (PKC) is a critical mediator of cell signaling and cancer growth. We show that PKC inhibitors decrease proliferation in squamous cell carcinoma of the head and neck (SCCHN) cells and abrogate growth of SCCHN tumors in mouse xenografts. Analysis of gene expression arrays reveals that PKC regulates cell cycle genes required for DNA synthesis. In particular, PKC increases cyclin E protein expression, cyclinE/cdk2 complex formation, and transcription of cyclin E and E2F target genes. Consistent with this mechanism, expression of cyclin E rescues the block in DNA synthesis caused by PKC inhibition. In SCCHN tissue, PKC and cyclin E expression increase progressively from normal and dysplastic to malignant human head and neck tissue. Furthermore, PKCÂ expression correlates with poor prognosis in SCCHN. These results demonstrate that PKC regulates growth by stimulating DNA synthesis through cyclin E and E2F and identify PKC as a therapeutic target that is highly expressed in aggressive SCCHN. Experiment Overall Design: 9 samples composed of treated replicates at three time points
Project description:Protein Kinase C alpha (PKC) is a critical mediator of cell signaling and cancer growth. We show that PKC inhibitors decrease proliferation in squamous cell carcinoma of the head and neck (SCCHN) cells and abrogate growth of SCCHN tumors in mouse xenografts. Analysis of gene expression arrays reveals that PKC regulates cell cycle genes required for DNA synthesis. In particular, PKC increases cyclin E protein expression, cyclinE/cdk2 complex formation, and transcription of cyclin E and E2F target genes. Consistent with this mechanism, expression of cyclin E rescues the block in DNA synthesis caused by PKC inhibition. In SCCHN tissue, PKC and cyclin E expression increase progressively from normal and dysplastic to malignant human head and neck tissue. Furthermore, PKC expression correlates with poor prognosis in SCCHN. These results demonstrate that PKC regulates growth by stimulating DNA synthesis through cyclin E and E2F and identify PKC as a therapeutic target that is highly expressed in aggressive SCCHN. Keywords: time course; dose response
Project description:Protein arginine methylation is an important process, which regulates diverse cellular functions including cell proliferation, RNA stability, DNA repair and gene transcription. Based on literature search, protein arginine methyltransferase (PRMT) indeed plays important roles in colon cancer pathophysiology. The PRMT expression level is involved in colon cancer patient’s survival and has been suggested to be a prognostic marker in colon cancer patients. Recently, our group found a novel methylation on epidermal growth factor receptor (EGFR), which affected EGFR downstream signaling. investigators further observed the methylation event on EGFR not only regulated tumor growth in mouse xenograft model but also influenced cetuximab response in colon cancer cell lines. To further study the clinical correlation between EGFR methylation and cetuximab response, we propose to detect EGFR methylation level in paraffin embedded tissue samples from colorectal cancer patients with or without cetuximab treatment by IHC staining and analyze its correlation with cetuximab response. This study will provide an insight to the strategy of colorectal cancer therapy.
Project description:Mitochondria are dynamic organelles that are important for cell growth and proliferation. Dysregulated mitochondrial dynamics are highly associated with the initiation and progression of various cancers, including ovarian cancer. However, the regulatory mechanism underlying mitochondrial dynamics is still not fully understood. Previously, our study showed that carnitine palmitoyltransferase 1A (CPT1A) is highly expressed in ovarian cancer cells and promotes the development of ovarian cancer. Here, we find that CPT1A regulates mitochondrial dynamics and promotes mitochondrial fission in ovarian cancer cells. Our study futher shows that CPT1A regulates mitochondrial fission and function through mitochondrial fission factor (MFF) to promote the growth and proliferation of ovarian cancer cells. Mechanistically, we show that CPT1A promotes succinylation of MFF at lysine 302 (K302), which protects against Parkin-mediated ubiquitin-proteasomal degradation of MFF. Finally, the study shows that MFF is highly expressed in ovarian cancer cells and that high MFF expression is associated with poor prognosis in patients with ovarian cancer. MFF inhibition significantly inhibits the progression of ovarian cancer in vivo. Overall, CPT1A regulates mitochondrial dynamics through MFF succinylation to promote the development of ovarian cancer. Moreover, our findings suggest that MFF is a potential therapeutic target for ovarian cancer.
Project description:mTORC1 is a conserved central controller of cell growth, which is commonly activated in hepatocellular carcinoma (HCC), driving liver tumorigenesis. In addition to its established cytoplasmic functions, mTORC1 is found in the nucleus where it regulates transcription by all three major RNA polymerases. However, precisely how mTORC1 controls gene expression remains poorly understood. Herein we show that mTORC1 interacts with the BAF SWI/SNF complex and regulates genome-wide chromatin remodeling through ARID1A. Mechanically, mTORC1 stimulates ubiquitination and proteasomal degradation of ARID1A protein through SCF ubiquitin ligase. mTORC1-ARID1A axis promotes chromatin remodeling and expression of YAP target genes, thereby enhancing oncogenic growth in vitro and in vivo. These findings reveal a novel nuclear mTORC1 function and the underlying mechanism that controls oncogenic chromatin remodeling to promote hepatocarcinogenesis.
Project description:Oncogene-induced senescence is an important tumor suppressor mechanism that limits proliferation of cells harboring oncogenic mutations. Through a genome-wide screen, we discovered a conserved snoRNA, SNORA13, that is required for this pathway. Although SNORA13 guides the pseudouridylation of a highly conserved nucleotide in the ribosomal decoding center, loss of this snoRNA minimally impacts translation. Instead, we found that SNORA13 negatively regulates ribosome biogenesis. Oncogenic stress perturbs ribosome biogenesis, resulting in the accumulation of free ribosomal proteins (RPs) that trigger p53 activation. We showed that SNORA13 interacts directly with RPL23, decreasing its incorporation into maturing 60S subunits and, consequently, increasing the pool of free RPs, thereby promoting the p53-mediated senescence program. Thus, SNORA13 regulates ribosome biogenesis and the p53 pathway through a non-canonical mechanism distinct from its role in guiding RNA modification. These findings expand our understanding of snoRNA functions and the roles of these abundant noncoding RNAs in cellular signaling.
Project description:Oncogene-induced senescence is an important tumor suppressor mechanism that limits proliferation of cells harboring oncogenic mutations. Through a genome-wide screen, we discovered a conserved snoRNA, SNORA13, that is required for this pathway. Although SNORA13 guides the pseudouridylation of a highly conserved nucleotide in the ribosomal decoding center, loss of this snoRNA minimally impacts translation. Instead, we found that SNORA13 negatively regulates ribosome biogenesis. Oncogenic stress perturbs ribosome biogenesis, resulting in the accumulation of free ribosomal proteins (RPs) that trigger p53 activation. We showed that SNORA13 interacts directly with RPL23, decreasing its incorporation into maturing 60S subunits and, consequently, increasing the pool of free RPs, thereby promoting the p53-mediated senescence program. Thus, SNORA13 regulates ribosome biogenesis and the p53 pathway through a non-canonical mechanism distinct from its role in guiding RNA modification. These findings expand our understanding of snoRNA functions and the roles of these abundant noncoding RNAs in cellular signaling.
Project description:mTORC1 is a conserved central controller of cell growth, which is commonly activated in hepatocellular carcinoma (HCC), driving liver tumorigenesis. In addition to its established cytoplasmic functions, mTORC1 is found in the nucleus where it regulates transcription by all three major RNA polymerases. However, precisely how mTORC1 controls gene expression remains poorly understood. Herein we show that mTORC1 interacts with the BAF SWI/SNF complex and regulates genome-wide chromatin remodeling through ARID1A. Mechanically, mTORC1 stimulates ubiquitination and proteasomal degradation of ARID1A protein through SCF ubiquitin ligase. mTORC1-ARID1A axis promotes chromatin remodeling and expression of YAP target genes, thereby enhancing oncogenic growth in vitro and in vivo. These findings reveal a novel nuclear mTORC1 function and the underlying mechanism that controls oncogenic chromatin remodeling to promote hepatocarcinogenesis.
Project description:Previous study demonstrated that HDAC3 has a critical role in MM proliferation; however, the underlying mechanism has not yet been elucidated. We identify that HDAC3 inhibition targets DNMT1 through dual regulations. We demonstrate that knockdown of DNMT1 leads to apoptosis and significant growth inhibition in myeloma cells. HDAC3 inhibition by gene silencing or HDAC3 selective inhibitor BG45 downregulates an oncoprotein c-Myc through its acetylation. c-Myc directly regulates DNMT1 expression at its enhancer region. Furthermore, HDAC3 directly regulates the stability of DNMT1 protein through its acetylation. Pharmaceutical inhibition of HDAC3 and DNMT1 synergistically induce MM growth inhibition in in vitro and in vivo settings. The goal of this analysis is to identify genes whose expression changes after shRNA-mediated knockdown of HDAC3 or DNMT1 using the human U133 plus 2.0 Affymetrix GeneChip in myeloma cell line (MM.1S).