Chaperonin Containing TCP-1 Subunits Research Articles

CCT3/ACTN4/TFRC axis protects hepatocellular carcinoma cells from ferroptosis by inhibiting iron endocytosis

Sorafenib is widely used in treating advanced hepatocellular carcinoma (HCC). However, its effectiveness in prolonging patient survival is limited by the development of drug resistance. To systematically investigate the resistance mechanisms of Sorafenib, an integrative analysis combining posttranslational modification (PTM) omics and CRISPR/Cas9 knockout library screening was conducted. This analysis identified ubiquitination at lysine 21 (K21) on chaperonin-containing TCP1 subunit 3 (CCT3) as being associated with Sorafenib resistance. Transcriptomic data from HCC patients treated with Sorafenib revealed that CCT3 expression was lower in responders compared to non-responders. Experimentally, inhibiting the expression of CCT3 sensitized HCC cells to Sorafenib and enhanced Sorafenib-induced ferroptosis. Additionally, CCT3 was found to interact with ACTN4, hindering the recycling of transferrin receptor protein 1 (TFRC) to the cell membrane, thus obstructing iron endocytosis. Mechanistically, the inhibition of ferroptosis by CCT3 depends on the deubiquitination of K6-linked non-degradative ubiquitination at its K21, which occurs upon Sorafenib treatment. Moreover, CCT3 knockdown enhanced the anti-tumor effects of Sorafenib in nude mice. In summary, we have identified a novel function of the chaperone protein. Targeting the CCT3/ACTN4/TFRC axis offers a promising strategy to enhance ferroptosis and overcome Sorafenib resistance in HCC.

CCT6A promotes cell proliferation in colon cancer by targeting BIRC5 associated with p53 status.

Chaperonin-containing TCP1 (CCT) is a multi-subunit complex, known to participate the correct folding of many proteins. Currently, the mechanism underlying CCT subunits in cancer progression is incompletely understood. Based on data analysis, the expression of CCT subunit 6 A (CCT6A) is found higher than the other subunits of CCT and correlated with an unfavorable prognosis in colon cancer. Here, we find CCT6A silencing suppresses colon cancer proliferation and survival phenotype in vitro and in vivo. CCT6A plays a role in cellular process, including the cell cycle, p53, and apoptosis signaling pathways. Further investigations have shown direct binding between CCT6A and both Wtp53 and Mutp53, and BIRC5 is found to act downstream of CCT6A. The highlight is that CCT6A inhibition significantly reduces BIRC5 expression independent of Wtp53 levels in Wtp53 cells. Conversely, in Mutp53 cells, downregulation of BIRC5 by CCT6A inhibition mainly depends on Mutp53 levels. Additionally, combined CCT6A inhibition and Wtp53 overexpression in Mutp53 cell lines effectively suppresses cell proliferation. It is concluded CCT6A is a potential oncogene that influences BIRC5 through distinct pathways in Wtp53 and Mutp53 cells.

Loss of PMFBP1 Disturbs Mouse Spermatogenesis by Downregulating HDAC3 Expression.

Polyamine modulating factor 1 binding protein (PMFBP1) acts as a scaffold protein for the maintenance of sperm structure. The aim of this study was further to identify the new role and molecular mechanism of PMFBP1 during mouse spermatogenesis. We identified a profile of proteins interacting with PMFBP1 by immunoprecipitation combined with mass spectrometry and demonstrated that class I histone deacetylases, particularly HDAC3 and chaperonin-containing TCP1 subunit 3 (CCT3), were potential interaction partners of PMFBP1 based on network analysis of protein-protein interactions and co-immunoprecipitation. Immunoblotting and immunochemistry assays showed that loss of Pmfbp1 would result in a decline in HDACs and change the proteomic profile of mouse testis, in which differently expressed proteins are associated with spermatogenesis and assembly of flagella, which was proved by proteomic analysis of testis tissue obtained from Pmfbp1-/- mice. After integrating with transcriptome data for Hdac3-/- and Sox30-/- round sperm obtained from a public database, RT-qPCR confirmed ring finger protein 151 (Rnf151) and ring finger protein 133 (Rnf133) were key downstream response factors of the Pmfbp1-Hdac axis affecting mouse spermatogenesis. Taken together, this study indicates a previously unidentified molecular mechanism of PMFBP1 in spermatogenesis whereby PMFBP1 interacts with CCT3, affecting the expression of HDAC3, followed by the downregulation of RNF151 and RNF133, resulting in an abnormal phenotype of sperm beyond the headless sperm tails. These findings not only advance our understanding of the function of Pmfbp1 in mouse spermatogenesis but also provide a typical case for multi-omics analysis used in the functional annotation of specific genes.

Multi-Omics Analysis and Verification of the Oncogenic Value of CCT8 in Pan-Cancers.

Chaperonin-containing TCP1 subunit 8 (CCT8) has been proved to be involved in the occurrence and development of some cancers. However, no study has reported the potential role of CCT8 in a pan-cancer manner. TIMER2.0, GEPIA2, UALCAN and Sangerbox were used to explore the expression, prognosis and methylation of CCT8. We used cBioPortal, TISIDB, SangerBox, TIMER2.0 and TISMO to investigate the genetic alteration of CCT8 and the relationship of CCT8 with molecular subtype, immune subtype, immune infiltration and immunotherapy response. CCT8-related genes were screened out through GEPIA and STRING for Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis. CCK-8, the colony formation assay, the wound healing assay and the Transwell assay were performed to explore the influence of CCT8 on proliferation and migration. CCT8 was highly expressed in most cancers with a poor prognosis. The expression level of CCT8, which was affected by the promoter region methylation and genetic alteration, was related to the molecular and immune subtype of cancers. Interestingly, CCT8 was positively associated with the activated CD4 T cells and type 2 T-helper cells. CCT8 played a vital role in the cell cycle and RNA transport of cancers, and it significantly inhibited the proliferation and migration of lung adenocarcinoma cells when it was knocked down. CCT8 plays an indispensable role in promoting the proliferation and migration of many cancers. CCT8 might be a biomarker of T-helper type 2 (Th2) cell infiltration and a promising therapeutic target for T-helper type 1(Th1)/Th2 imbalance.

CCT6A promotes esophageal squamous cell carcinoma cell proliferation, invasion and epithelial-mesenchymal transition by activating TGF-β/Smad/c-Myc pathway.

Chaperonin-containing TCP1 subunit 6A (CCT6A) facilitates several malignant cancer behaviors, but its regulation of esophageal squamous cell carcinoma (ESCC) has not been reported. This study aimed to investigate the effect of CCT6A on cell proliferation, apoptosis, invasion and epithelial-mesenchymal transition (EMT) and its interaction with the TGF-β/Smad/c-Myc pathway in ESCC. CCT6A expression was detected in ESCC and normal esophageal epithelial cell lines by RT‒qPCR and western blotting. Furthermore, CCT6A siRNA, negative control (NC) siRNA, CCT6A encoding plasmid and NC encoding plasmid were transfected into OE21 and TE-1 cells. Subsequently, CCT6A siRNA- and NC siRNA-transfected cells were treated with TGF-β for rescue experiments. Cell proliferation, apoptosis, invasion, and E-cadherin/N-cadherin and p-Smad2/p-Smad3/c-Myc expression were detected. CCT6A expression was increased in KYSE-180, TE-1, TE-4 and OE21 cells compared with HET-1A cells. In both OE21 and TE-1 cells, CCT6A knockdown inhibited cell proliferation, invasion and N-cadherin expression while promoting cell apoptosis and E-cadherin expression; meanwhile, CCT6A overexpression had the opposite effects. Furthermore, in both OE21 and TE-1 cells, CCT6A knockdown decreased p-Smad2/Smad2, p-Smad3/Smad3 and c-Myc/GAPDH expression; CCT6A overexpression had the opposite effects. Next, TGF-β facilitated cell proliferation, invasion, and N-cadherin, p-Smad2/Smad2, p-Smad3/Smad2 and c-Myc/GAPDH expression while repressing cell apoptosis and E-cadherin expression in OE21 and TE-1 cells; importantly, TGF-β could compensate for the regulation of CCT6A knockdown on these activities. CCT6A facilitates ESCC malignant activities by activating the TGF-β/Smad/c-Myc pathway, which sheds light on the identification of a possible therapeutic target in the management of ESCC.

Structural and Dynamic Disturbances Revealed by Molecular Dynamics Simulations Predict the Impact on Function of CCT5 Chaperonin Mutations Associated with Rare Severe Distal Neuropathies

Mutations in genes encoding molecular chaperones, for instance the genes encoding the subunits of the chaperonin CCT (chaperonin containing TCP-1, also known as TRiC), are associated with rare neurodegenerative disorders. Using a classical molecular dynamics approach, we investigated the occurrence of conformational changes and differences in physicochemical properties of the CCT5 mutations His147Arg and Leu224Val associated with a sensory and a motor distal neuropathy, respectively. The apical domain of both variants was substantially but differently affected by the mutations, although these were in other domains. The distribution of hydrogen bonds and electrostatic potentials on the surface of the mutant subunits differed from the wild-type molecule. Structural and dynamic analyses, together with our previous experimental data, suggest that genetic mutations may cause different changes in the protein-binding capacity of CCT5 variants, presumably within both hetero- and/or homo-oligomeric complexes. Further investigations are necessary to elucidate the molecular pathogenic pathways of the two variants that produce the two distinct phenotypes. The data and clinical observations by us and others indicate that CCT chaperonopathies are more frequent than currently believed and should be investigated in patients with neuropathies.

CCT6A knockdown suppresses osteosarcoma cell growth and Akt pathway activation in vitro.

We assessed the role of the protein-coding gene chaperonin-containing TCP1 subunit 6A (CCT6A) in osteosarcoma, as this is currently unknown. Using data from the R2 online genomic analysis and visualization application, we found that CCT6A messenger ribonucleic acid (RNA) expression is increased in osteosarcoma tissue and cells. Transfection of CCT6A small interfering RNA into cultured osteosarcoma cells revealed that CCT6A knockdown attenuates cell growth, cell viability, cell survival, and induced apoptosis and cell cycle progression at the G0/G1 phases. Moreover, CCT6A knockdown downregulated phospho-protein kinase B (p-Akt), cyclinD1 and B-cell lymphoma-2, whereas upregulated Bcl-2-associated X-protein expression. Thus, CCT6A knockdown inhibits cell proliferation, induces cell apoptosis, and suppresses the Akt pathway.

The malaria parasite chaperonin containing TCP-1 (CCT) complex: Data integration with other CCT proteomes.

The multi-subunit chaperonin containing TCP-1 (CCT) is an essential molecular chaperone that functions in the folding of key cellular proteins. This paper reviews the interactome of the eukaryotic chaperonin CCT and its primary clients, the ubiquitous cytoskeletal proteins, actin and tubulin. CCT interacts with other nascent proteins, especially the WD40 propeller proteins, and also assists in the assembly of several protein complexes. A new proteomic dataset is presented for CCT purified from the human malarial parasite, P. falciparum (PfCCT). The CCT8 subunit gene was C-terminally FLAG-tagged using Selection Linked Integration (SLI) and CCT complexes were extracted from infected human erythrocyte cultures synchronized for maximum expression levels of CCT at the trophozoite stage of the parasite's asexual life cycle. We analyze the new PfCCT proteome and incorporate it into our existing model of the CCT system, supported by accumulated data from biochemical and cell biological experiments in many eukaryotic species. Together with measurements of CCT mRNA, CCT protein subunit copy number and the post-translational and chemical modifications of the CCT subunits themselves, a cumulative picture is emerging of an essential molecular chaperone system sitting at the heart of eukaryotic cell growth control and cell cycle regulation.

Chaperonin-containing TCP-1 subunit 2-mediated aggrephagy: A potential target for treating neurodegeneration.

Chaperonin-containing TCP-1 subunit 2-mediated aggrephagy: A potential target for treating neurodegeneration.

Chaperonin-Containing TCP1 Subunit 5 Protects Against the Effect of Mer Receptor Tyrosine Kinase Knockdown in Retinal Pigment Epithelial Cells by Interacting With Filamentous Actin and Activating the LIM-Kinase 1/Cofilin Pathway.

Retinitis pigmentosa (RP), characterized by the gradual loss of rod and cone photoreceptors that eventually leads to blindness, is the most common inherited retinal disorder, affecting more than 2.5 million people worldwide. However, the underlying pathogenesis of RP remains unclear and there is no effective cure for RP. Mutations in the Mer receptor tyrosine kinase (MERTK) gene induce the phagocytic dysfunction of retinal pigment epithelium (RPE) cells, leading to RP. Studies have indicated that filamentous actin (F-actin)—which is regulated by chaperonin-containing TCP1 subunit 5 (CCT5)—plays a vital role in phagocytosis in RPE cells. However, whether CCT5/F-actin signaling is involved in MERTK-associated RP remains largely unknown. In the present study, we specifically knocked down MERTK and CCT5 through siRNA transfection and examined the expression of CCT5 and F-actin in human primary RPE (HsRPE) cells. We found that MERTK downregulation inhibited cell proliferation, migration, and phagocytic function; significantly decreased the expression of F-actin; and disrupted the regular arrangement of F-actin. Importantly, our findings firstly indicate that CCT5 interacts with F-actin and is inhibited by MERTK siRNA in HsRPE cells. Upregulating CCT5 using CCT5-specific lentiviral vectors (CCT5-Le) rescued the cell proliferation, migration, and phagocytic function of HsRPE cells under the MERTK knockdown condition by increasing the expression of F-actin and restoring its regular arrangement via the LIMK1/cofilin, but not the SSH1/cofilin, pathway. In conclusion, CCT5 protects against the effect of MERTK knockdown in HsRPE cells and demonstrates the potential for effective treatment of MERTK-associated RP.

Suppression of CCT3 inhibits melanoma cell proliferation by downregulating CDK1 expression.

The eukaryotic chaperonin family is vital for cell survival. The dysregulation of chaperonin-containing TCP-1 subunit 3 (CCT3) is implicated in several types of malignant tumors' development. However, its functional role in melanoma remains unknown. Here we elucidate the functional contribution to CCT3 to melanoma progression. The results indicated that CCT3 highly expressed in melanoma tissues, and CCT3 overexpression is correlated with clinical stage in melanoma patients. Knockdown of CCT3 by shRNA in melanoma cells inhibited cell proliferation and cell cycle progression and induced cell apoptosis in vitro. In vivo, tumor growth in the nude mice was significantly inhibited after CCT3 silencing. Importantly, the gene array analysis showed that CCT3 depletions inhibited cyclins and cell cycle regulation signaling and further evaluation demonstrated that CDK1 expression was significantly decreased after CCT3 knockdown. Additionally, Functional rescues experiments also indicated that decreased cell proliferation due to CCT3 silencing was rescued by CDK1 overexpression. Overall, our findings suggest that CCT3 depletions prohibited melanoma progression by downregulating CDK1 expression and is a potential therapeutic target for melanoma.

Interaction with the CCT chaperonin complex limits APOBEC3A cytidine deaminase cytotoxicity.

The APOBEC3 cytidine deaminases are implicated as the cause of a prevalent somatic mutation pattern found in cancer genomes. The APOBEC3 enzymes act as viral restriction factors by mutating viral genomes. Mutation of the cellular genome is presumed to be an off-target activity of the enzymes, although the regulatory measures for APOBEC3 expression and activity remain undefined. It is therefore difficult to predict circumstances that enable APOBEC3 interaction with cellular DNA that leads to mutagenesis. The APOBEC3A (A3A) enzyme is the most potent deaminase of the family. Using proteomics, we evaluate protein interactors of A3A to identify potential regulators. We find that A3A interacts with the chaperonin-containing TCP-1 (CCT) complex, a cellular machine that assists in protein folding and function. Importantly, depletion of CCT results in A3A-induced DNA damage and cytotoxicity. Evaluation of cancer genomes demonstrates an enrichment of A3A mutational signatures in cancers with silencing mutations in CCT subunit genes. Together, these data suggest that the CCT complex interacts with A3A, and that disruption of CCT function results in increased A3A mutational activity.

SEC61G identified as a prognostic biomarker of head and neck squamous cell carcinoma

PurposeIt is of obvious interest to identify clinical prognosis-related oncogenes in HNSCC (head and neck squamous cell carcinoma).MethodsBased on the available datasets within the TCGA (The Cancer Genome Atlas) and the GEO (Gene Expression Omnibus) databases, the potential mechanism of action of the SEC61G (SEC61 translocon subunit gamma) gene in HNSCC tumorigenesis was explored by several bioinformatics approaches.ResultsThere was a higher expression level of SEC61G in primary HNSCC tumor tissues than in normal tissues. Moreover, highly expressed SEC61G was statistically associated with the poor survival prognosis of HNSCC patients. When HPV (human papilloma virus) was considered, we also observed a relatively lower proportion of “arm-level gain” and “high amplification” types of CNA (copy-number alteration) in the HNSCC-HPV (+) group than in the HNSCC-HPV (−) group. Additionally, we identified SEC61G CAN-correlated genes, such as CCT6A (chaperonin-containing TCP1 subunit 6A) and HUS1 (HUS1 checkpoint clamp component), and found a correlation between SEC61G copy-number segments and prognosis related to overall and progression-free survival intervals of HNSCC patients. Moreover, the molecular regulation mechanisms of the spliceosome, ribosome, proteasome degradation, cell adhesion, and immune infiltration of B and CD8+ T cells may contribute to the involvement of SEC61G in the pathogenesis of HNSCC.ConclusionsThe SEC61G gene was identified for the first time as a prognostic biomarker of HNSCC. The detailed underlying mechanism merits further research.

Chaperonin-Containing TCP1 Subunit 6A Is a Prognostic Potential Biomarker That Correlates With the Presence of Immune Infiltrates in Colorectal Cancer.

AimsChaperonin-containing TCP1 subunit (CCT) 6A is an oncogenic 6th subunit of the CCT family. Nevertheless, not much is documented regarding its function in colorectal cancer (COAD). This investigation seeks to explore the role of CCT6A in the prognosis of COAD.Main MethodsSequencing data from the Gene Expression Omnibus (GEO) and Cancer Genome Atlas database (TCGA) were employed to analyze the expression of CCT6A and its involvement in various regulatory networks behind COAD. Oncomine and Gene Expression Profiling Interactive Analysis (GEPIA) analyzed Levels of expression and survival rates, while GEPIA was used to uncover further the functional networks that involved CCT6A. Database for Annotation, Visualization, and Integrated Discovery (DAVID) tools were used to interpret Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathways. Evaluation of the expression levels of CCT6A in COAD samples was also verified via immunohistochemistry.Key FindingsWe found that the expression of CCT6A is up-regulated in COAD. CCT6A correlated with poor prognosis and decreased immune infiltrates such as CD4+ T cells, B cells, and dendritic cells. CCT6A is increased in COAD patients. CCT6A is associated with several gene networks related to the DDX family and mismatch repair pathways.SignificanceOur data showed that data mining was able to uncover data regarding levels of CCT6A and its involvement in genetic regulating pathways in COAD.

Comprehensive analysis of the expression of chaperonin containing TCP1 subunits (CCTs) and their influence on prognosis in hepatocellular carcinoma.

BackgroundChaperonin containing TCP1 subunits (CCTs) are important components in the folding of newly synthesized proteins and are involved in cell growth, proliferation, and apoptosis in eukaryotes. Accumulating evidence indicates that dysregulation of CCTs is involved in tumorigenesis. However, the roles of distinct CCTs in the occurrence and development of hepatocellular carcinoma (HCC) are largely unknown. To address this issue, the mRNA expression and the prognostic value of different CCTs in HCC patients were analyzed.MethodsThe mRNA expression levels of CCTs in tumors and the relationship between clinical parameters and CCTs in patients with HCC were analyzed by using ONCOMINE and Gene Expression Profiling Interactive Analysis (GEPIA) databases. The prognostic values of CCTs in HCC patients were determined by using the Kaplan-Meier plotter. The genetic alteration, coexpression, and interaction of CCTs and their frequently altered neighboring genes in HCC patients were analyzed by c-BioPortal. Gene functional enrichment and signaling pathways affected by CCTs in patients with HCC were investigated by using R software.ResultsThe mRNA expression levels of CCTs were significantly upregulated in HCC tissues. Upregulated expression of CCTs was found to be significantly associated with alpha-fetoprotein (AFP), pathological grade, and macro- and microvascular invasion, but there was no correlation with the Child-Pugh classification. Moreover, survival analysis showed that the upregulated expression of CCTs correlated with shorter overall survival (OS) and disease-free survival (DFS) in patients with HCC. The observed genetic alteration rate of CCTs was as high as 51.39% in HCC and was associated with a poorer prognosis in HCC patients. Pathway analysis confirmed that the expression levels of PI3K/AKT pathway genes were affected by CCT genetic alterations.ConclusionsOur results suggest that CCTs could be promising prognostic biomarkers and potential therapeutic targets for HCC patients. However, further studies are required to validate our findings and promote the clinical utility of CCTs in HCC patients.

Investigating Chaperonin-Containing TCP-1 subunit 2 as an essential component of the chaperonin complex for tumorigenesis

Chaperonin-containing TCP-1 (CCT or TRiC) is a multi-subunit complex that folds many of the proteins essential for cancer development. CCT is expressed in diverse cancers and could be an ideal therapeutic target if not for the fact that the complex is encoded by eight distinct genes, complicating the development of inhibitors. Few definitive studies addressed the role of specific subunits in promoting the chaperonin’s function in cancer. To this end, we investigated the activity of CCT2 (CCTβ) by overexpressing or depleting the subunit in breast epithelial and breast cancer cells. We found that increasing total CCT2 in cells by 1.3-1.8-fold using a lentiviral system, also caused CCT3, CCT4, and CCT5 levels to increase. Likewise, silencing cct2 gene expression by ~50% caused other CCT subunits to decrease. Cells expressing CCT2 were more invasive and had a higher proliferative index. CCT2 depletion in a syngeneic murine model of triple negative breast cancer (TNBC) prevented tumor growth. These results indicate that the CCT2 subunit is integral to the activity of the chaperonin and is needed for tumorigenesis. Hence CCT2 could be a viable target for therapeutic development in breast and other cancers.

High expression of chaperonin-containing TCP1 subunit 3 may induce dismal prognosis in multiple myeloma.

The prognosis role of CCT3 in MM and the possible pathways it involved were studied in our research. By analyzing ten independent datasets (including 48 healthy donors, 2220 MM, 73 MGUS, and 6 PCL), CCT3 was found to express higher in MM than healthy donors, and the expression level was gradually increased from MGUS, SMM, MM to PCL (all P < 0.01). By analyzing three independent datasets (GSE24080, GSE2658, and GSE4204), we found that CCT3 was a significant indicator of poor prognosis (all P < 0.01). KEGG and GSEA analysis showed that CCT3 expression was associated with JAK-STAT3 pathway, Hippo signaling pathway, and WNT signaling pathway. In addition, different expressed genes analysis revealed MYC, which was one of the downstream genes regulated by JAK-STAT3 pathway, was upregulated in MM. This confirms that JAK-STAT3 signaling pathway may promote the progress of disease which was regulated by CCT3 expression. Our study revealed that CCT3 may play a supporting role at the diagnosis of myeloid, and high expression of CCT3 suggested poor prognosis in MM. CCT3 expression may promote the progression of MM mainly by regulating MYC through JAK-STAT3 signaling pathway.

Bioinformatics analysis of the prognostic value of CCT6A and associated signalling pathways in breast cancer.

Breast cancer (BC) is the most frequently diagnosed type of cancer and the leading cause of cancer-associated mortality among women worldwide. However, the molecular basis for the pathogenesis of BC requires further exploration. Recent studies have demonstrated that chaperonin-containing TCP1 subunit 6A (CCT6A) efficiently suppresses transforming growth factor-β-mediated metastasis by inhibiting the function of SMAD family member 2 in lung cancer. However, the functional significance of CCT6A in other types of cancer, including BC, remains to be investigated. Therefore, this study evaluated CCT6A expression in BC samples, and further analysed its association with survival, clinicopathological parameters and related signalling pathways using online datasets. The present study indicated that CCT6A expression was significantly higher in BC tissues compared with in surrounding noncancerous tissues at both mRNA and protein levels. Furthermore, increased CCT6A expression was significantly associated with poor survival, including overall survival, relapse-free survival, distant metastasis-free survival and post progression survival, in patients with BC. Pathway finder analysis indicated that CCT6A was significantly associated with the cell cycle, and its expression was significantly positively correlated with cyclin (CCN)B2 and CCNA2 expression. Taken together, to the best of our knowledge, the present study is the first to indicate that CCT6A may serve a significant role in BC tumour progression.

TRiC/CCT chaperonins are essential for organ growth by interacting with insulin/TOR signaling in Drosophila

Organ size is regulated by intercellular signaling for cell growth and proliferation. The TOR pathway mediates a key signaling mechanism for controlling cell size and number in organ growth. Chaperonin containing TCP-1 (CCT) is a complex that assists protein folding and function, but its role in animal development is largely unknown. Here we show that the CCT complex is required for organ growth by interacting with the TOR pathway in Drosophila. Reduction of CCT4 results in growth defects by affecting both cell size and proliferation. Loss of CCT4 causes preferential cell death anterior to the morphogenetic furrow in the eye disc and within wing pouch in the wing disc. Depletion of any CCT subunit in the eye disc results in headless phenotype. Overgrowth by active TOR signaling is suppressed by CCT RNAi. The CCT complex physically interacts with TOR signaling components including TOR, Rheb, and S6K. Loss of CCT leads to decreased phosphorylation of S6K and S6 while increasing phosphorylation of Akt. Insulin/TOR signaling is also necessary and sufficient for promoting CCT complex transcription. Our data provide evidence that the CCT complex regulates organ growth by directly interacting with the TOR signaling pathway.

Targeting chaperonin containing TCP1 (CCT) as a molecular therapeutic for small cell lung cancer.

Identifying new druggable targets is desired to meet the needs for effective cancer treatments. To this end, we previously reported the efficacy of a therapeutic peptide called CT20p that displays selective cytotoxicity through inhibition of a multi-subunit, protein-folding complex called Chaperonin-Containing TCP-1 (CCT). To investigate the role of CCT in cancer progression, we examined protein levels of CCT subunits in liver, prostate, and lung cancer using human tissue microarrays. We found that these cancers expressed higher levels of CCT2 as compared to normal tissues. Small cell lung cancer (SCLC) stood out as having statistically significant difference in CCT2. Higher levels of CCT2 in tumors from lung cancer patients were also associated with decreased survival. Using SCLC cell lines, we observed detectable amounts of CCT subunits and cells were susceptible to killing by CT20p. Treatment with CT20p, delivered to cells using polymeric nanoparticles, was cytotoxic to all SCLC cell lines, decreasing the levels of CCT client proteins like STAT3. In contrast, treatment with a STAT3 inhibitor was effective in one of the SCLC cell lines. While we found that CCT levels could vary in cell lines, normal tissues had low levels of CCT and minimal toxicity to liver or kidney function was observed in mice treated with CT20p. These results indicate that in SCLC, changes in CCT levels could be used as a biomarker for diagnosis and that targeting CCT for inhibition with CT20p is a promising treatment approach for those cancers such as SCLC that currently lack targeted therapeutics.