Cryptochrome 2 acetylation attenuates its antiproliferative effect in breast cancer.

Breast cancer is the most commonly diagnosed cancer, and its global impact is increasing. Its onset and progression are influenced by multiple cues, one of which is the disruption of the internal circadian clock. Cryptochrome 2 (Cry2) genetic dysregulation may lead to the development of some diseases and even tumors. In addition, post-translational modifications can alter the Cry2 function. Here, we aimed to elucidate the post-translational regulations of Cry2 and its role in breast cancer pathogenesis. We identified p300-drived acetylation as a novel Cry2 post-translational modification, which histone deacetylase 6 (HDAC6) could reverse. Furthermore, we found that Cry2 inhibits breast cancer proliferation, but its acetylation impairs this effect. Finally, bioinformatics analysis revealed that genes repressed by Cry2 in breast cancer were mainly enriched in the NF-κB pathway, and acetylation reversed this repression. Collectively, these results indicate a novel Cry2 regulation mechanism and provide a rationale for its role in breast tumorigenesis.

DACH1 inhibits breast cancer cell invasion and metastasis by down-regulating the transcription of matrix metalloproteinase 9.

Human Dachshund homolog 1 (DACH1) is usually defined as a tumor suppressor, which plays an influential role in tumor growth and metastasis in a variety of cancer cells. However, the underlying mechanisms in these process are not yet fully clarified. In this study, DACH1 inhibited the invasion and metastasis of breast cancer cells by decreasing MMP9 expression. Mechanistically, DACH1 represses the transcriptional level of MMP9 by interacting with p65 and c-Jun at the NF-κB and AP-1 binding sites in MMP9 promoter respectively, and the association of DACH1 and p65 promote the recruitment of HDAC1 to the NF-κB binding site in MMP9 promoter, resulting in the reduction of the acetylation level and the transcriptional activity of p65. Accordingly, the level of MMP9 was decreased. In conclusion, we found a new mechanism that DACH1 could inhibit the metastasis of breast cancer cells by inhibiting the expression of MMP9.

Codelivery of High-Molecular-Weight Poly-porphyrins and HIF-1α Inhibitors for In Vivo Synergistic Anticancer Therapy.

Photodynamic therapy (PDT) is showing great potential in the treatment of cancer diseases, and photosensitizers play crucial roles in absorbing the energy of light and generating reactive oxygen species (ROS) during PDT. Most of the photosensitizers bearing macrocyclic structures have strong hydrophobicity and suffer from the π-π interaction and undesired aggregation caused quenching (ACQ), which severely limit the PDT efficacy. Moreover, the continuous oxygen consumption during PDT also leads to the upregulated expression of hypoxia-inducible factor-1α (HIF-1α), which can aggravate the growth of tumors. To overcome the abovementioned problems, polymerized photosensitizers repelled by flexible thioketal linkers were designed and synthesized using a multicomponent polymerization (MCP) method to afford the poly-porphyrins with high molecular weight (Mw > 20 000 g/mol) under room temperature. The ACQ effect could be significantly inhibited by introducing flexible chains and increasing Mw, leading to the improvement in the singlet oxygen quantum yield and phototoxicity simultaneously. An HIF-1α inhibitor, Lificiguat (YC-1) was synthesized as a chemodrug and codelivered with poly-porphyrins to decrease the expression of HIF-1α and inhibit tumor growth under hypoxia. With the synergistic PDT and chemotherapy, poly-porphyrin/YC-1 micelles showed excellent therapeutic antitumor efficacy both in vitro and in vivo.

Linear and high-molecular-weight poly-porphyrins for efficient photodynamic therapy.

Photodynamic therapy (PDT) holds great potential in cancer treatment due to the advantages of non-invasiveness, negligible side-effect, and high spatiotemporal selectivity. Porphyrin is the most widely used photosensitizer in clinical treatment. However, its PDT efficacy is always limited by the undesired aggregation caused quenching (ACQ) effect originating from the planar and rigid structure. In this work, a linear polymeric porphyrin with "structure defects" was developed to overcome the ACQ effect for most of the photosensitizers with conjugated macrocycles. Compared to porphyrin monomers, poly-porphyrins could improve singlet oxygen generation ability, and the singlet oxygen quantum yield enhanced with increasing molecular weight of poly-porphyrins. To achieve efficient in vivo PDT, PEG and acetazolamide were conjugated to the optimized poly-porphyrins to afford pP-PEG-AZ nanoparticles (pP-PEG-AZ NPs) with excellent stability, efficient in vitro intracellular internalization, negligible dark-toxicity, notable photo-toxicity, and in vivo anti-cancer efficacy based on combined PDT and anti-angiogenesis therapy.

Acetylation of ELF5 suppresses breast cancer progression by promoting its degradation and targeting CCND1.

E74-like ETS transcription factor 5 (ELF5) is involved in a wide spectrum of biological processes, e.g., mammogenesis and tumor progression. We have identified a list of p300-interacting proteins in human breast cancer cells. Among these, ELF5 was found to interact with p300 via acetylation, and the potential acetylation sites were identified as K130, K134, K143, K197, K228, and K245. Furthermore, an ELF5-specific deacetylase, SIRT6, was also identified. Acetylation of ELF5 promoted its ubiquitination and degradation, but was also essential for its antiproliferative effect against breast cancer, as overexpression of wild-type ELF5 and sustained acetylation-mimicking ELF5 mutant could inhibit the expression of its target gene CCND1. Taken together, the results demonstrated a novel regulation of ELF5 as well as shedding light on its important role in modulation of breast cancer progression.

TIMELESS inhibits breast cancer cell invasion and metastasis by down-regulating the expression of MMP9.

Breast cancer is the first killer leading to female death, and tumor metastasis is one of the important factors leading to the death of patients, but the specific mechanism of breast cancer metastasis is not very clear at present. Our study showed that overexpression of TIMELESS could significantly inhibit the invasion and metastasis of breast cancer cells ZR-75-30 and the assembly of F-actin protein. On the contrary, knockdown of TIMELESS promoted the invasion and metastasis of breast cancer cells. Further study revealed that TIMELESS overexpression decreased the mRNA and protein levels of MMP9. Furthermore, TIMELESS could interact with p65, leading to repress the association of p65 and its acetyltransferase CBP and down-regulating the acetylation level of p65, which inhibited the activation of NF-κB signal pathway. In conclusion, our research showed that TIMELESS may repress the invasion and metastasis of breast cancer cells via inhibiting the acetylation of p65, inhibiting the activation of NF-κB, thus down-regulating the expression of MMP9, and then inhibiting the invasion and metastasis of breast cancer cells.

FBXL10 promotes ERRα protein stability and proliferation of breast cancer cells by enhancing the mono-ubiquitylation of ERRα.

The underlying mechanism of orphan nuclear receptor estrogen-related receptor α (ERRα) in breast cancer was investigated by identifying its interaction partners using mass spectrometry. F-box and leucine-rich repeat protein 10 (FBXL10), which modulates various physiological processes, may interact with ERRα in breast cancer. Here, we investigated the interaction between FBXL10 and ERRα, and their protein expression and correlation in breast cancer. Mechanical studies revealed that FBXL10 stabilized ERRα protein levels by reducing its poly-ubiquitylation and promoting its mono-ubiquitylation. The reporter gene assay and examination of ERRα target genes validated the increased transcriptional activity of ERRα due to its increased protein levels by FBXL10. FBXL10 also increased ERRα enrichment at the promoter region of its target genes. Functionally, FBXL10 facilitated the ERRα/peroxisome proliferator-activated receptor gamma coactivator 1 ß (PGC1ß)-mediated proliferation and tumorigenesis of breast cancer cells in vitro and in vivo. Our results uncovered a molecular mechanism linking the mono-ubiquitylation and protein stability of ERRα to functional interaction with FBXL10. Moreover, a novel regulatory axis of FBXL10 and ERRα regulating the proliferation and tumorigenesis of breast cancer cells was established.

SUMOylation of MCL1 protein enhances its stability by regulating the ubiquitin-proteasome pathway.

In cancers, apoptosis evasion through dysregulation of pro-apoptotic and anti-apoptotic intracellular signals is a recurring event. Accordingly, selective inhibition of specific proteins represents an exciting therapeutic opportunity. Myeloid cell leukemia 1 (MCL1) is an anti-apoptotic protein of the BCL-2 family, which is overexpressed in many cancers. Here, we demonstrate that MCL1 can be modified by the small ubiquitin-like modifier (SUMO) at K234 and K238 sites. The SUMOylation of MCL1 can improve its stability by inhibiting the MCL1 ubiquitin-proteasome pathway mediated by the Tripartite motif-containing 11 (TRIM11, a novel MCL1 ubiquitin E3 ligase that we identify in this study). Moreover, SUMOylation of MCL1 increases the proliferation of cancer cells by inhibiting apoptosis. These results suggest that the SUMOylation of MCL1 may play a significant role in the regulation of its function.

Plasma Inter-Alpha-Trypsin Inhibitor Heavy Chains H3 and H4 Serve as Novel Diagnostic Biomarkers in Human Colorectal Cancer.

OBJECTIVE: Inter-alpha-trypsin inhibitor heavy chain H3 (ITIH3) and inter-alpha-trypsin inhibitor heavy chain H4 (ITIH4) are heavy chains of protein members belonging to the ITI family, which was associated with inflammation and carcinogenesis. However, the diagnostic value of ITIH3 and ITIH4 in human colorectal cancer (CRC) remains unknown. METHODS: In total, 101 CRC patients and 156 healthy controls were enrolled. The concentrations of ITIH3 and ITIH4 proteins in plasma samples of participants were assessed using enzyme-linked immunosorbent assay. ITIH3 and ITIH4 expressions in human CRC tissues were additionally assessed via immunohistochemical staining (IHC). Receiver operating characteristic (ROC) was applied to estimate the diagnostic power of the two proteins, and the net reclassification improvement (NRI) was adopted to evaluate the incremental predictive ability of ITIH3/ITIH4 when added to the tissue inhibitor of metalloproteinase-1 (TIMP-1). RESULTS: The plasma concentration of ITIH3 in CRC patients (median: 4.370 µg/mL; range: 2.152-8.170 µg/mL) was significantly lower than that in healthy subjects (median: 4.715 µg/mL; range: 2.665-10.257 µg/mL; p < 0.001), while the ITIH4 plasma level in subjects with CRC (median: 0.211 µg/mL; range: 0.099-0.592 µg/mL) was markedly increased relative to that in the control group (median: 0.134 µg/mL; range: 0.094-0.460 µg/mL, p < 0.001). Consistently, IHC score assessment showed a dramatic reduction in ITIH3 expression and, conversely, upregulation of ITIH4 in colorectal carcinoma specimens relative to adjacent normal colorectal tissues (p < 0.001 in both cases). The area under the curve (AUC) of the ROC for ITIH4 (AUC = 0.801, 95% CI: 0.745-0.857) was higher than that for ITIH3 (AUC = 0.638, 95% CI: 0.571-0.704, both p values < 0.001). The AUC of the ROC for combined ITIH3 and ITIH4 was even higher than that for carcinoembryonic antigen. NRI results showed that combining ITIH3 and ITIH4 with TIMP-1 significantly improved diagnostic accuracy (NRI = 17.12%, p = 0.002) for CRC patients compared to TIMP-1 alone. CONCLUSIONS: Circulating ITIH3 and ITIH4 levels are associated with carcinogenesis in CRC, supporting their potential diagnostic utility as surrogate biomarkers for colorectal cancer detection.

Circadian protein BMAL1 promotes breast cancer cell invasion and metastasis by up-regulating matrix metalloproteinase9 expression.

BACKGROUND: Metastasis is an important factor in the poor prognosis of breast cancer. As an important core clock protein, brain and muscle arnt-like 1 (BMAL1) is closely related to tumorigenesis. However, the molecular mechanisms that mediate the role of BMAL1 in invasion and metastasis remain largely unknown. In this study, we investigated the BMAL1 may take a crucial effect in the progression of breast cancer cells. METHODS: BMAL1 and MMP9 expression was measured in breast cell lines. Transwell and scratch wound-healing assays were used to detect the movement of cells and MTT assays and clonal formation assays were used to assess cells' proliferation. The effects of BMAL1 on the MMP9/NF-κB pathway were examined by western blotting, co-immunoprecipitation and mammalian two-hybrid. RESULTS: In our study, it showed that cell migration and invasion were significantly enhanced when overexpressed BMAL1. Functionally, overexpression BMAL1 significantly increased the mRNA and protein level of matrix metalloproteinase9 (MMP9) and improved the activity of MMP9. Moreover, BMAL1 activated the NF-κB signaling pathway by increasing the phosphorylation of IκB and promoted human MMP9 promoter activity by interacting with NF-kB p65, leading to increased expression of MMP9. When overexpressed BMAL1, CBP (CREB binding protein) was recruited to enhance the activity of p65 and further activate the NF-κB signaling pathway to regulate the expression of its downstream target genes, including MMP9, TNFα, uPA and IL8, and then promote the invasion and metastasis of breast cancer cells. CONCLUSIONS: This study confirmed a new mechanism by which BMAL1 up-regulated MMP9 expression to increase breast cancer metastasis, to provide research support for the prevention and treatment of breast cancer.

Checkpoint suppressor 1 suppresses transcriptional activity of ERα and breast cancer cell proliferation via deacetylase SIRT1.

Breast cancer is a highly heterogeneous carcinoma in women worldwide, but the underlying mechanisms that account for breast cancer initiation and development have not been fully established. Mounting evidence indicates that Checkpoint suppressor 1 (CHES1) is tightly associated with tumorigenesis and prognosis in many types of cancer. However, the definitive function of CHES1 in breast cancer remains to be explored. Here we showed that CHES1 had a physical interaction with estrogen receptor-α (ERα) and repressed the transactivation of ERα in breast cancer cells. Mechanistically, the interaction between CHES1 and ERα enhanced the recruitment of nicotinamide adenine dinucleotide (NAD+) deacetylase Sirtuin 1 (SIRT1), and it further induced SIRT1-mediated ERα deacetylation and repression on the promoter-binding enrichment of ERα. In addition, we also found that the expression of CHES1 was repressed by estrogen-ERα signaling and the expression level of CHES1 was significantly downregulated in ERα-positive breast cancer. The detailed mechanism was that ERα may directly bind to CHES1 potential promoter via recognizing the conserved estrogen response element (ERE) motif in response to estrogen stimulation. Functionally, CHES1 inhibited ERα-mediated proliferation and tumorigenesis of breast cancer cells in vivo and in vitro. Totally, these results identified a negative cross-regulatory loop between ERα and CHES1 that was required for growth of breast cancer cells, it might uncover novel insight into molecular mechanism of CHES1 involved in breast cancer and provide new avenues for molecular-targeted therapy in hormone-regulated breast cancer.

α-catenin SUMOylation increases IκBα stability and inhibits breast cancer progression.

α-catenin has been demonstrated to suppress several different types of cancers. Here we demonstrate that α-catenin is modified by SUMO protein, which covalently binds α-catenin at the carboxy terminus at lysine 870. Substitution of lysine 870 with arginine completely abolishes α-catenin SUMOylation. This modification can be removed by SENP1. However, α-catenin SUMOylation does not affect its stability and subcellular localization. In addition, we observed that the SUMOylation-deficient α-catenin mutant has a reduced interaction with IκBα which prevents subsequent ubiquitination of IκBα, and therefore a reduced suppression of expression of the NF-κB target genes TNF-α, IL-8, VEGF, and uPA. In addition, the α-catenin SUMOylation mutant shows impaired suppression of tumor growth. These results demonstrate that SUMOylation at lysine 870 of α-catenin plays a key role in the suppression of the NF-κB pathway, which inhibits breast cancer tumor growth and migration.

Krüppel-like factor 9 down-regulates matrix metalloproteinase 9 transcription and suppresses human breast cancer invasion.

Krüppel-like factor 9 (KLF9) plays critical roles in several types of tumor. However, the biological functions and the underlying mechanisms of KLF9 in breast cancer metastasis are still unknown. Here, we found the expression of KLF9 was significantly down-regulated in breast cancer and was inversely correlated with the expression of matrix metalloproteinase 9 (MMP9) in breast cancer patients. Functionally, KLF9 transcriptionally down-regulated MMP9 expression and inhibited the metastasis of breast cancer cells. Mechanistically, KLF9 repressed human MMP9 promoter activity by binding to the CACCC motif and interacting with NF-κB p50/p65, which interacted with the NF-κB response element of the MMP9 promoter, leading to decreased expression of MMP9. In the context of breast cancer, KLF9 promoted the accumulation of HDAC1, thereby decreasing the acetylation of the KLF9-binding site on the MMP9 promoter, and this might be the molecular basis of KLF9-mediated inhibition of MMP9 transcription. In addition to MMP9, KLF9 also down-regulated several other NF-κB targets, such as TNF-α, VEGFA and uPA in breast cancer cells. Taken together, these results uncovered a new mechanism by which KLF9 could down-regulate MMP9 expression to inhibit breast cancer metastasis.