A proteomic approach to understand MMP-3-driven developmental processes in the postnatal cerebellum: Chaperonin CCT6A and MAP kinase as contributing factors

Chaperonin-containing TCP1 subunit 6A inhibition via TRIM21-mediated K48-linked ubiquitination suppresses triple-negative breast cancer progression through the AKT signalling pathway

BACKGROUND

Triple-negative breast cancer (TNBC) is distinguished by a significant likelihood of distant recurrence and an unfavourable prognosis. However, the underlying molecules and mechanisms have not been fully elucidated.

METHODS

We investigated the expression profile and clinical relevance of chaperonin-containing TCP1 subunit 6A (CCT6A) in TNBC. We performed cell function assays on TNBC cells with CCT6A knockdown or overexpression. To further explore the mechanism of action of CCT6A, RNA sequencing and co-immunoprecipitation-mass spectrometry analyses were utilized. Rescue and ubiquitination assays evaluated the impact of TRIM21-mediated CCT6A ubiquitination and degradation on TNBC progression in vitro and in vivo. Finally, we studied the potential of Ipatasertib, a pharmacological AKT inhibitor, and/or anti-PD1 therapy in inhibiting TNBC progression.

RESULTS

Elevated CCT6A expression in TNBC patients was associated with an adverse prognosis and lymph node metastasis. Mechanistically, CCT6A facilitated cell migration, invasion, epithelial-mesenchymal transition and proliferation by activating the phosphatidylinositol 3-kinase (PI3K)/AKT pathway. The TRIM21 RING domain is an E3 ligase, facilitating the K48-linked ubiquitination-mediated degradation of CCT6A, thereby impeding TNBC progression. Moreover, in the tumour tissues of the CCT6A-overexpressing mice, the quantity of CD8+ T cells and the concentration of secreted interferon-gamma were decreased, whereas in the group double-overexpression of CCT6A and TRIM21, they were elevated; the opposite was observed in the knockdown and double-knockdown groups. Ipatasertib demonstrated enhanced efficacy in inhibiting cell proliferation, invasion and migration in TNBC cells ectopically expressing CCT6A. When Ipatasertib and anti-PD1 therapies were combined, both the tumour volume and mass exhibited a notable reduction, while the expression of CD45+CD8+ T cells increased, and that of CD45+CD4+CTLA4+ and CD45+CD4+PD1+ T cells decreased.

CONCLUSIONS

Our findings indicate that TRIM21 inhibits TNBC progression by facilitating the K48-linked ubiquitination-mediated degradation of CCT6A via the PI3K/AKT signalling pathway. This highlights the potential of Ipatasertib and/or anti-PD1 as therapeutic strategies, particularly for TNBC patients overexpressing CCT6A.

KEY POINTS

Chaperonin TCP1 subunit 6A (CCT6A) plays an oncogenic role in triple-negative breast cancer (TNBC) through the AKT signaling pathway. TRIM21 facilitated K48-linked ubiquitination-mediated degradation of CCT6A, thereby impeding TNBC progression. Our study collectively underscores the potential of Ipatasertib in conjunction with anti-PD1 therapy as a promising strategy to counteract CCT6A/AKT hyperactivity-driven TNBC progression.

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

OBJECTIVE

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.

METHODS

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.

RESULTS

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.

CONCLUSION

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.

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.

CCT6A may act as a potential biomarker reflecting tumor size, lymphatic metastasis, FIGO stage, and prognosis in cervical cancer patients

OBJECTIVE

Chaperonin-containing tailless complex polypeptide subunit 6A (CCT6A) is a critical regulator and newly identified clinical biomarker of several cancers, while its correlation with the clinical characteristics and prognosis of cervical cancer patients is unclear. Therefore, this study aimed to explore this issue.

METHODS

Chaperonin-containing tailless complex polypeptide subunit 6A expression in tumor and tumor-adjacent tissues from 198 cervical cancer patients who underwent resection were detected by immunohistochemistry assay and reverse transcription-quantitative polymerase chain reaction. Besides, the clinicopathological features and survival data of cervical cancer patients were collected.

RESULTS

Chaperonin-containing tailless complex polypeptide subunit 6A protein and mRNA levels were both increased in tumor tissues compared with tumor-adjacent tissues (both p < 0.001). Receiver operating characteristic curves showed that CCT6A protein (AUC: 0.774, 95% CI: 0.729-0.819) and mRNA levels (AUC: 0.904, 95% CI: 0.874-0.934) well discriminated tumor tissues from tumor-adjacent tissues. Besides, correlation analyses found that CCT6A protein and mRNA levels were positively correlated with lymph node metastasis and FIGO stage (all p < 0.05), apart from which CCT6A mRNA level was also positively associated with tumor size (p = 0.032). In addition, CCT6A protein and mRNA levels were negatively correlated with accumulating disease-free survival (both p < 0.05); meanwhile CCT6A mRNA level was negatively associated with accumulating overall survival as well (p = 0.010).

CONCLUSION

Chaperonin-containing tailless complex polypeptide subunit 6A is elevated in tumor tissues, and its high expression associates with larger tumor size, lymph node metastasis, higher FIGO stage, and worse prognosis in cervical cancer patients.

Two predicted models based on ceRNAs and immune cells in lung adenocarcinoma

Background

It is well accepted that both competitive endogenous RNAs (ceRNAs) and immune microenvironment exert crucial roles in the tumor prognosis. The present study aimed to find prognostic ceRNAs and immune cells in lung adenocarcinoma (LUAD).

Materials and Methods

More specifically, we explored the associations of crucial ceRNAs with the immune microenvironment. The Cancer Genome Atlas (TCGA) database was employed to obtain expression profiles of ceRNAs and clinical data. CIBERSORT was utilized to quantify the proportion of 22 immune cells in LUAD.

Results

We constructed two cox regression models based on crucial ceRNAs and immune cells to predict prognosis in LUAD. Subsequently, seven ceRNAs and seven immune cells were involved in prognostic models. We validated both predicted models via an independent cohort GSE72094. Interestingly, both predicted models proved that the longer patients were smoking, the higher risk scores would be obtained. We further investigated the relationships between seven genes and immune/stromal scores via the ESTIMATE algorithm. The results indicated that CDC14A and H1F0 expression were significantly related to stromal scores/immune scores in LUAD. Moreover, based on the result of the ceRNA model, single-sample gene set enrichment analysis (ssGSEA) suggested that differences in immune status were evident between high- and low-risk groups.

Chaperonin containing t-complex polypeptide 1 subunit 6A correlates with lymph node metastasis, abnormal carcinoembryonic antigen and poor survival profiles in non-small cell lung carcinoma

Background

This study aimed to investigate the correlation of chaperonin containing t-complex polypeptide 1 subunit 6A (CCT6A) expression with clinicopathological features and survival profiles in non-small cell lung carcinoma (NSCLC) patients.

Methods

A total of 381 NSCLC patients with Tumor, Node, Metastasis (TNM) stage I–IIIA who underwent tumor resection were retrospectively screened. Immunohistochemistry staining and semi-quantitative scoring were used to evaluate CCT6A expression in tumor and adjacent tissues. Clinicopathological features were retrieved. Disease-free survival (DFS) and overall survival (OS) were calculated.

Results

CCT6A expression was elevated in tumor tissue (CCT6A high 47.5% vs. low 52.5%) compared with adjacent tissue (CCT6A high 30.4% vs. low 69.6%) (P < 0.001), and ROC curve displayed that CCT6A could distinguish tumor tissue from adjacent tissue. Moreover, tumor CCT6A high expression was associated with lymph node metastasis (P = 0.001), elevated TNM stage (P = 0.002), and abnormal carcinoembryonic antigen (P = 0.022). Kaplan–Meier curves displayed that tumor CCT6A high expression was negatively correlated with DFS and OS (all P < 0.001). Cox’s regression analysis disclosed that tumor CCT6A high expression independently predicted worse DFS (P < 0.001) (hazard ratio (HR) 1.659 (95% confidence interval (CI) 1.318–2.089)), and OS (P < 0.001) (HR 1.779 (95%CI 1.378–2.298)).

Conclusions

CCT6A may present some clinical value in the management of NSCLC.

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.

CCT6A suppresses SMAD2 and promotes prometastatic TGF-β signaling

Paradoxically, during early tumor development in many cancer types, TGF-β acts as a tumor suppressor, whereas in the advanced stages of these cancers, increased TGF-β expression is linked to high metastasis and poor prognosis. These findings suggest that unidentified mechanisms may function to rewire TGF-β signaling toward its prometastatic role in cancer cells. Our current study using non-small-cell lung carcinoma (NSCLC) cell lines, animal models, and clinical specimens demonstrates that suppression of SMAD2, with SMAD3 function intact, switches TGF-β-induced transcriptional responses to a prometastatic state. Importantly, we identified chaperonin containing TCP1 subunit 6A (CCT6A) as an inhibitor and direct binding protein of SMAD2 and found that CCT6A suppresses SMAD2 function in NSCLC cells and promotes metastasis. Furthermore, selective inhibition of SMAD3 or CCT6A efficiently suppresses TGF-β-mediated metastasis. Our findings provide a mechanism that directs TGF-β signaling toward its prometastatic arm and may contribute to the development of therapeutic strategies targeting TGF-β for NSCLC.

Mechanisms of NMDA Receptor- and Voltage-Gated L-Type Calcium Channel-Dependent Hippocampal LTP Critically Rely on Proteolysis That Is Mediated by Distinct Metalloproteinases

Long-term potentiation (LTP) is widely perceived as a memory substrate and in the hippocampal CA3-CA1 pathway, distinct forms of LTP depend on NMDA receptors (nmdaLTP) or L-type voltage-gated calcium channels (vdccLTP). LTP is also known to be effectively regulated by extracellular proteolysis that is mediated by various enzymes. Herein, we investigated whether in mice hippocampal slices these distinct forms of LTP are specifically regulated by different metalloproteinases (MMPs). We found that MMP-3 inhibition or knock-out impaired late-phase LTP in the CA3-CA1 pathway. Interestingly, late-phase LTP was also decreased by MMP-9 blockade. When both MMP-3 and MMP-9 were inhibited, both early- and late-phase LTP was impaired. Using immunoblotting, in situ zymography, and immunofluorescence, we found that LTP induction was associated with an increase in MMP-3 expression and activity in CA1 stratum radiatum. MMP-3 inhibition and knock-out prevented the induction of vdccLTP, with no effect on nmdaLTP. L-type channel-dependent LTP is known to be impaired by hyaluronic acid digestion. We found that slice treatment with hyaluronidase occluded the effect of MMP-3 blockade on LTP, further confirming a critical role for MMP-3 in this form of LTP. In contrast to the CA3-CA1 pathway, LTP in the mossy fiber-CA3 projection did not depend on MMP-3, indicating the pathway specificity of the actions of MMPs. Overall, our study indicates that the activation of perisynaptic MMP-3 supports L-type channel-dependent LTP in the CA1 region, whereas nmdaLTP depends solely on MMP-9.

SIGNIFICANCE STATEMENT

Various types of long-term potentiation (LTP) are correlated with distinct phases of memory formation and retrieval, but the underlying molecular signaling pathways remain poorly understood. Extracellular proteases have emerged as key players in neuroplasticity phenomena. The present study found that L-type calcium channel-dependent LTP in the CA3-CA1 hippocampal projection is critically regulated by the activity of matrix metalloprotease 3 (MMP-3), in contrast to NMDAR-dependent LTP regulated by MMP-9. Moreover, the induction of LTP was associated with an increase in MMP-3 expression and activity. Finally, we found that the digestion of hyaluronan, a principal extracellular matrix component, disrupted the MMP-3-dependent component of LTP. These results indicate that distinct MMPs might act as molecular switches for specific types of LTP.

Congenital Anophthalmia and Binocular Neonatal Enucleation Differently Affect the Proteome of Primary and Secondary Visual Cortices in Mice

In blind individuals, visually deprived occipital areas are activated by non-visual stimuli. The extent of this cross-modal activation depends on the age at onset of blindness. Cross-modal inputs have access to several anatomical pathways to reactivate deprived visual areas. Ectopic cross-modal subcortical connections have been shown in anophthalmic animals but not in animals deprived of sight at a later age. Direct and indirect cross-modal cortical connections toward visual areas could also be involved, yet the number of neurons implicated is similar between blind mice and sighted controls. Changes at the axon terminal, dendritic spine or synaptic level are therefore expected upon loss of visual inputs. Here, the proteome of V1, V2M and V2L from P0-enucleated, anophthalmic and sighted mice, sharing a common genetic background (C57BL/6J x ZRDCT/An), was investigated by 2-D DIGE and Western analyses to identify molecular adaptations to enucleation and/or anophthalmia. Few proteins were differentially expressed in enucleated or anophthalmic mice in comparison to sighted mice. The loss of sight affected three pathways: metabolism, synaptic transmission and morphogenesis. Most changes were detected in V1, followed by V2M. Overall, cross-modal adaptations could be promoted in both models of early blindness but not through the exact same molecular strategy. A lower metabolic activity observed in visual areas of blind mice suggests that even if cross-modal inputs reactivate visual areas, they could remain suboptimally processed.

Binocular pattern deprivation interferes with the expression of proteins involved in primary visual cortex maturation in the cat

Background

Binocular pattern deprivation from eye opening (early BD) delays the maturation of the primary visual cortex. This delay is more pronounced for the peripheral than the central visual field representation within area 17, particularly between the age of 2 and 4 months [Laskowska-Macios, Cereb Cortex, 2014].

Results

In this study, we probed for related dynamic changes in the cortical proteome. We introduced age, cortical region and BD as principal variables in a 2-D DIGE screen of area 17. In this way we explored the potential of BD-related protein expression changes between central and peripheral area 17 of 2- and 4-month-old BD (2BD, 4BD) kittens as a valid parameter towards the identification of brain maturation-related molecular processes. Consistent with the maturation delay, distinct developmental protein expression changes observed for normal kittens were postponed by BD, especially in the peripheral region. These BD-induced proteomic changes suggest a negative regulation of neurite outgrowth, synaptic transmission and clathrin-mediated endocytosis, thereby implicating these processes in normal experience-induced visual cortex maturation. Verification of the expression of proteins from each of the biological processes via Western analysis disclosed that some of the transient proteomic changes correlate to the distinct behavioral outcome in adult life, depending on timing and duration of the BD period [Neuroscience 2013;255:99-109].

Conclusions

Taken together, the plasticity potential to recover from BD, in relation to ensuing restoration of normal visual input, appears to rely on specific protein expression changes and cellular processes induced by the loss of pattern vision in early life.

Electronic supplementary material

The online version of this article (doi:10.1186/s13041-015-0137-7) contains supplementary material, which is available to authorized users.

Proteases at work: cues for understanding neural development and degeneration

Proteolytical processing of membrane bound molecules is a fundamental mechanism for the degradation of these proteins as well as for controlling cell-to-cell communication, which is at the basis of tissue development and homeostasis. Members of families of metalloproteinases and intra-membrane proteases are major effectors of these events. A recent workshop in Baeza, Spain, was devoted to discuss how this mechanism coordinates brain development and how its dysfunction leads to brain pathologies. Herein we summarize the findings presented during this workshop, which illuminate the role of metalloproteinases, including matrix metalloproteinase, A Disintegrin and Metalloproteinase-proteases and intra-membrane proteases, in the regulation of neurogenesis, axon guidance, and synaptogenesis as well as in neurodegeneration. Indeed, there is increasing evidence that proteolysis at the membrane is directly linked to neuropathologies such as Alzheimer Disease and autism spectrum or prion disorders. These proteolytic events are tightly regulated and we are just at the beginning of understanding how these processes could be exploited to design therapeutic treatments aimed at alleviating psychiatric and neurodegenerative pathologies.