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1.
J Control Release ; 368: 548-565, 2024 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-38462044

RESUMEN

Cancer treatment is challenged due to immunosuppressive inflammatory tumour microenvironment (TME) caused by infiltration of tumour-promoting and inhibition of tumour-inhibiting immune cells. Here, we report the engineering of chimeric nanomicelles (NMs) targeting the cell proliferation using docetaxel (DTX) and inflammation using dexamethasone (DEX) that alters the immunosuppressive TME. We show that a combination of phospholipid-DTX conjugate and PEGylated-lipid-DEX conjugate can self-assemble to form sub-100 nm chimeric NMs (DTX-DEX NMs). Anti-cancer activities against syngeneic and xenograft mouse models showed that the DTX-DEX NMs are more effective in tumour regression, enhance the survival of mice over other treatment modes, and alter the tumour stroma. DTX-DEX NMs cause a significant reduction in myeloid-derived suppressor cells, alter the polarization of macrophages, and enhance the accumulation of cytotoxic CD4+ and CD8+ T cells in tumour tissues, along with alterations in cytokine expression. We further demonstrated that these DTX-DEX NMs inhibit the synthesis of prostaglandins, especially PGE2, by targeting the cyclooxygenase 2 that is partly responsible for immunosuppressive TME. Therefore, this study presents, for the first time, the engineering of lithocholic acid-derived chimeric NMs that affect the prostaglandin pathway, alter the TME, and mitigate tumour progression with enhanced mice survival.


Asunto(s)
Antineoplásicos , Prostaglandinas , Humanos , Ratones , Animales , Prostaglandinas/farmacología , Linfocitos T CD8-positivos , Docetaxel/uso terapéutico , Docetaxel/farmacología , Antineoplásicos/uso terapéutico , Antineoplásicos/farmacología , Terapia de Inmunosupresión , Microambiente Tumoral , Línea Celular Tumoral
2.
J Clin Invest ; 134(8)2024 Feb 29.
Artículo en Inglés | MEDLINE | ID: mdl-38421735

RESUMEN

RAD54 and BLM helicase play pivotal roles during homologous recombination repair (HRR) to ensure genome maintenance. BLM amino acids (aa 181-212) interact with RAD54 and enhance its chromatin remodeling activity. Functionally, this interaction heightens HRR, leading to a decrease in residual DNA damage in colon cancer cells. This contributes to chemoresistance in colon cancer cells against cisplatin, camptothecin, and oxaliplatin, eventually promoting tumorigenesis in preclinical colon cancer mouse models. ChIP-Seq analysis and validation revealed increased BLM and RAD54 corecruitment on the MRP2 promoter in camptothecin-resistant colon cancer cells, leading to BLM-dependent enhancement of RAD54-mediated chromatin remodeling. We screened the Prestwick small-molecule library, with the intent to revert camptothecin- and oxaliplatin-induced chemoresistance by disrupting the RAD54-BLM interaction. Three FDA/European Medicines Agency-approved candidates were identified that could disrupt this interaction. These drugs bound to RAD54, altered its conformation, and abrogated RAD54-BLM-dependent chromatin remodeling on G5E4 and MRP2 arrays. Notably, the small molecules also reduced HRR efficiency in resistant lines, diminished anchorage-independent growth, and hampered the proliferation of tumors generated using camptothecin- and oxaliplatin-resistant colon cancer cells in both xenograft and syngeneic mouse models in BLM-dependent manner. Therefore, the 3 identified small molecules can serve as possible viable candidates for adjunct therapy in colon cancer treatment.


Asunto(s)
Neoplasias del Colon , Resistencia a Antineoplásicos , Humanos , Animales , Ratones , Oxaliplatino/farmacología , Reparación del ADN , Camptotecina , Neoplasias del Colon/tratamiento farmacológico , Neoplasias del Colon/genética , Proliferación Celular
3.
J Biol Chem ; 299(9): 105087, 2023 09.
Artículo en Inglés | MEDLINE | ID: mdl-37495109

RESUMEN

Mutations in the DNA helicase RECQL4 lead to Rothmund-Thomson syndrome (RTS), a disorder characterized by mitochondrial dysfunctions, premature aging, and genomic instability. However, the mechanisms by which these mutations lead to pathology are unclear. Here we report that RECQL4 is ubiquitylated by a mitochondrial E3 ligase, MITOL, at two lysine residues (K1101, K1154) via K6 linkage. This ubiquitylation hampers the interaction of RECQL4 with mitochondrial importer Tom20, thereby restricting its own entry into mitochondria. We show the RECQL4 2K mutant (where both K1101 and K1154 are mutated) has increased entry into mitochondria and demonstrates enhanced mitochondrial DNA (mtDNA) replication. We observed that the three tested RTS patient mutants were unable to enter the mitochondria and showed decreased mtDNA replication. Furthermore, we found that RECQL4 in RTS patient mutants are hyperubiquitylated by MITOL and form insoluble aggregate-like structures on the outer mitochondrial surface. However, depletion of MITOL allows RECQL4 expressed in these RTS mutants to enter mitochondria and rescue mtDNA replication. Finally, we show increased accumulation of hyperubiquitylated RECQL4 outside the mitochondria leads to the cells being potentiated to increased mitophagy. Hence, we conclude regulating the turnover of RECQL4 by MITOL may have a therapeutic effect in patients with RTS.


Asunto(s)
Mitocondrias , Mitofagia , RecQ Helicasas , Ubiquitina-Proteína Ligasas , Humanos , ADN Mitocondrial/genética , Mitocondrias/metabolismo , Mitofagia/genética , Mutación , RecQ Helicasas/genética , RecQ Helicasas/metabolismo , Síndrome Rothmund-Thomson/genética , Ubiquitina-Proteína Ligasas/genética , Ubiquitina-Proteína Ligasas/metabolismo , Ubiquitinación , Replicación del ADN/genética
4.
Sci Adv ; 9(26): eadf2746, 2023 06 30.
Artículo en Inglés | MEDLINE | ID: mdl-37390205

RESUMEN

Treatment of triple-negative breast cancer (TNBC) is challenging because of its "COLD" tumor immunosuppressive microenvironment (TIME). Here, we present a hydrogel-mediated localized delivery of a combination of docetaxel (DTX) and carboplatin (CPT) (called DTX-CPT-Gel therapy) that ensured enhanced anticancer effect and tumor regression on multiple murine syngeneic and xenograft tumor models. DTX-CPT-Gel therapy modulated the TIME by an increase of antitumorigenic M1 macrophages, attenuation of myeloid-derived suppressor cells, and increase of granzyme B+CD8+ T cells. DTX-CPT-Gel therapy elevated ceramide levels in tumor tissues that activated the protein kinase R (PKR)-like endoplasmic reticulum kinase (PERK)-mediated unfolded protein response (UPR). This UPR-mediated activation of apoptotic cell death led to release of damage-associated molecular patterns, thereby activating the immunogenic cell death that could even clear the metastatic tumors. This study provides a promising hydrogel-mediated platform for DTX-CPT therapy that induces tumor regression and effective immune modulation and, therefore, can be explored further for treatment of TNBC.


Asunto(s)
Hidrogeles , Neoplasias de la Mama Triple Negativas , Humanos , Animales , Ratones , Muerte Celular Inmunogénica , Linfocitos T CD8-positivos , Neoplasias de la Mama Triple Negativas/tratamiento farmacológico , Ceramidas , Modelos Animales de Enfermedad , Inmunosupresores , Respuesta de Proteína Desplegada , Microambiente Tumoral
5.
ACS Biomater Sci Eng ; 9(5): 2558-2571, 2023 05 08.
Artículo en Inglés | MEDLINE | ID: mdl-37067339

RESUMEN

Glioblastoma (GBM) is a deadly tumor of the central nervous system (CNS) having a dismal prognosis. miRNA-based therapeutics hold immense potential for GBM therapy; however, its delivery remains a daunting challenge. MicroRNA-210 has been established as a critical oncomiR in GBM. Our group has developed novel, PEI-functionalized transglutaminase-based nanoflowers (TGNFs, ∼61 nm in diameter) for the efficient delivery of anti-miR-210 to glioblastoma cells in vitro. TGNFs show low cytotoxicity to normal human fibroblasts, do not affect the liver and kidney health of CD1 mice, and offer >95% anti-miR encapsulation efficiency, serum stability, and protection against polyanion moieties. Their synthesis is cost-effective and does not involve the application of harsh chemicals. TGNFs successfully delivered anti-miR-210 to glioblastoma cells, decreasing cellular proliferation and migration and increasing apoptosis. Overall, this research highlights the potential of TGNFs as delivery agents in miRNA inhibition therapy and encourages further preclinical studies to explore the potential of miR-210 as a therapeutic target in GBM and various other cancers where the oncogenic role of miR-210 has been well-established.


Asunto(s)
Glioblastoma , MicroARNs , Humanos , Ratones , Animales , Glioblastoma/tratamiento farmacológico , Glioblastoma/genética , Antagomirs/uso terapéutico , Polietileneimina/uso terapéutico , Línea Celular Tumoral , MicroARNs/genética
6.
STAR Protoc ; 3(4): 101710, 2022 12 16.
Artículo en Inglés | MEDLINE | ID: mdl-36136752

RESUMEN

Mitochondrial polymerase gamma (PolγA) is the only replicative polymerase in mitochondria. To determine PolγA ubiquitylation in cells, Flag-PolγA and MITOL are overexpressed, and subsequently the immunoprecipitated Flag-PolγA is checked for ubiquitylation. Alternately, in vitro synthesized PolγA and MITOL are used to determine whether PolγA is ubiquitylated. Either anti-ubiquitin or anti-Flag antibody is used to detect the ubiquitylated product. Thus, we provide a detailed, reliable, highly reproducible protocol for detecting ubiquitylation of PolγA by MITOL, both in cells and in vitro. For complete details on the use and execution of this protocol, please refer to Hussain et al. (2021).


Asunto(s)
Mitocondrias , Ubiquitina-Proteína Ligasas , Ubiquitina-Proteína Ligasas/metabolismo , ADN Polimerasa gamma/genética , ADN Polimerasa gamma/metabolismo , Ubiquitinación , Mitocondrias/metabolismo , Ubiquitina/metabolismo
8.
J Cell Sci ; 134(15)2021 08 01.
Artículo en Inglés | MEDLINE | ID: mdl-34369561

RESUMEN

Meta-analysis of transcripts in colon adenocarcinoma patient tissues led to the identification of a DNA damage responsive miR signature called DNA damage sensitive miRs (DDSMs). DDSMs were experimentally validated in the cancerous colon tissues obtained from an independent cohort of colon cancer patients and in multiple cellular systems with high levels of endogenous DNA damage. All the tested DDSMs were transcriptionally upregulated by a common intestine-specific transcription factor, CDX2. Reciprocally, DDSMs were repressed via the recruitment of HDAC1/2-containing complexes onto the CDX2 promoter. These miRs downregulated multiple key targets in the DNA damage response (DDR) pathway, namely BRCA1, ATM, Chk1 (also known as CHEK1) and RNF8. CDX2 directly regulated the DDSMs, which led to increased tumor volume and metastasis in multiple preclinical models. In colon cancer patient tissues, the DDSMs negatively correlated with BRCA1 levels, were associated with decreased probability of survival and thereby could be used as a prognostic biomarker. This article has an associated First Person interview with the first author of the paper.


Asunto(s)
Adenocarcinoma , Neoplasias del Colon , MicroARNs , Factor de Transcripción CDX2/genética , Neoplasias del Colon/genética , Daño del ADN/genética , Proteínas de Unión al ADN/genética , Humanos , MicroARNs/genética , Factores de Transcripción , Ubiquitina-Proteína Ligasas
9.
Biomater Sci ; 9(16): 5626-5639, 2021 Aug 21.
Artículo en Inglés | MEDLINE | ID: mdl-34254078

RESUMEN

Herein, we present the engineering of a supramolecular nanomicellar system that is composed of self-assembled units of the PEGylated lithocholic acid (LCA)-docetaxel (DTX) conjugate (LCA-DTX-PEG). We tethered a short polyethylene glycol unit to LCA and used an esterase-sensitive ester linkage between DTX and LCA. The LCA-DTX-PEG conjugate formed nanomicelles (LCA-DTX-PEG NMs) with ∼160 nm hydrodynamic diameter that are sensitive to cellular esterases and maximized the release of DTX under high esterase exposure. LCA-DTX-PEG NMs were found to be effective as the parent drug in breast cancer cells by stabilizing tubulin and arresting the cells in the G2/M phase. We determined the maximum tolerated dose (MTD) and systemic and vital organ toxicity of LCA-DTX-PEG NMs in mice, rats, and rabbits. LCA-DTX-PEG NMs showed a MTD of >160 mg kg-1 and are found to be safe in comparison with their parent FDA-approved drug formulation (Taxotere® or DTX-TS) that is highly toxic. LCA-DTX-PEG NMs effectively reduced the tumor volume and increased the survival of 4T1 tumor-bearing mice with improved blood circulation time of the drug and its higher accumulation in tumor tissues. Therefore, this study highlights the potential of PEGylated bile acid-drug conjugate based nanomicelles for the development of next generation cancer therapeutics.


Asunto(s)
Antineoplásicos , Micelas , Animales , Antineoplásicos/uso terapéutico , Ácidos y Sales Biliares , Línea Celular Tumoral , Docetaxel , Portadores de Fármacos , Ratones , Conejos , Ratas
10.
Front Genet ; 12: 634789, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-33777104

RESUMEN

DNA damage repair response is an important biological process involved in maintaining the fidelity of the genome in eukaryotes and prokaryotes. Several proteins that play a key role in this process have been identified. Alterations in these key proteins have been linked to different diseases including cancer. BLM is a 3'-5' ATP-dependent RecQ DNA helicase that is one of the most essential genome stabilizers involved in the regulation of DNA replication, recombination, and both homologous and non-homologous pathways of double-strand break repair. BLM structure and functions are known to be conserved across many species like yeast, Drosophila, mouse, and human. Genetic mutations in the BLM gene cause a rare, autosomal recessive disorder, Bloom syndrome (BS). BS is a monogenic disease characterized by genomic instability, premature aging, predisposition to cancer, immunodeficiency, and pulmonary diseases. Hence, these characteristics point toward BLM being a tumor suppressor. However, in addition to mutations, BLM gene undergoes various types of alterations including increase in the copy number, transcript, and protein levels in multiple types of cancers. These results, along with the fact that the lack of wild-type BLM in these cancers has been associated with increased sensitivity to chemotherapeutic drugs, indicate that BLM also has a pro-oncogenic function. While a plethora of studies have reported the effect of BLM gene mutations in various model organisms, there is a dearth in the studies undertaken to investigate the effect of its oncogenic alterations. We propose to rationalize and integrate the dual functions of BLM both as a tumor suppressor and maybe as a proto-oncogene, and enlist the plausible mechanisms of its deregulation in cancers.

11.
PLoS Biol ; 19(3): e3001139, 2021 03.
Artículo en Inglés | MEDLINE | ID: mdl-33657094

RESUMEN

Mutations in mitochondrial replicative polymerase PolγA lead to progressive external ophthalmoplegia (PEO). While PolγA is the known central player in mitochondrial DNA (mtDNA) replication, it is unknown whether a regulatory process exists on the mitochondrial outer membrane which controlled its entry into the mitochondria. We now demonstrate that PolγA is ubiquitylated by mitochondrial E3 ligase, MITOL (or MARCH5, RNF153). Ubiquitylation in wild-type (WT) PolγA occurs at Lysine 1060 residue via K6 linkage. Ubiquitylation of PolγA negatively regulates its binding to Tom20 and thereby its mitochondrial entry. While screening different PEO patients for mitochondrial entry, we found that a subset of the PolγA mutants is hyperubiquitylated by MITOL and interact less with Tom20. These PolγA variants cannot enter into mitochondria, instead becomes enriched in the insoluble fraction and undergo enhanced degradation. Hence, mtDNA replication, as observed via BrdU incorporation into the mtDNA, was compromised in these PEO mutants. However, by manipulating their ubiquitylation status by 2 independent techniques, these PEO mutants were reactivated, which allowed the incorporation of BrdU into mtDNA. Thus, regulated entry of non-ubiquitylated PolγA may have beneficial consequences for certain PEO patients.


Asunto(s)
ADN Polimerasa gamma/metabolismo , Proteínas de la Membrana/metabolismo , Ubiquitina-Proteína Ligasas/metabolismo , ADN Polimerasa gamma/fisiología , Replicación del ADN , ADN Mitocondrial/genética , Células HEK293 , Humanos , Proteínas de la Membrana/fisiología , Mitocondrias/metabolismo , Proteínas Mitocondriales/metabolismo , Mutación , Ubiquitina-Proteína Ligasas/fisiología , Ubiquitinación
12.
Angew Chem Int Ed Engl ; 60(10): 5394-5399, 2021 03 01.
Artículo en Inglés | MEDLINE | ID: mdl-33258265

RESUMEN

In this study, we describe the engineering of sub-100 nm nanomicelles (DTX-PC NMs) derived from phosphocholine derivative of docetaxel (DTX)-conjugated lithocholic acid (DTX-PC) and poly(ethylene glycol)-tethered lithocholic acid. Administration of DTX-PC NMs decelerate tumor progression and increase the mice survivability compared to Taxotere (DTX-TS), the FDA-approved formulation of DTX. Unlike DTX-TS, DTX-PC NMs do not cause any systemic toxicity and slow the decay rate of plasma DTX concentration in rodents and non-rodent species including non-human primates. We further demonstrate that DTX-PC NMs target demethylation of CpG islands of Sparcl1 (a tumor suppressor gene) by suppressing DNA methyltransferase activity and increase the expression of Sparcl1 that leads to tumor regression. Therefore, this unique system has the potential to improve the quality of life in cancer patients and can be translated as a next-generation chemotherapeutic.


Asunto(s)
Antineoplásicos/uso terapéutico , Docetaxel/uso terapéutico , Epigénesis Genética/efectos de los fármacos , Ácido Litocólico/análogos & derivados , Ácido Litocólico/uso terapéutico , Neoplasias/tratamiento farmacológico , Animales , Antineoplásicos/síntesis química , Antineoplásicos/farmacocinética , Proteínas de Unión al Calcio/genética , Proteínas de Unión al Calcio/metabolismo , Línea Celular Tumoral , Islas de CpG , Desmetilación , Progresión de la Enfermedad , Docetaxel/síntesis química , Docetaxel/farmacocinética , Proteínas de la Matriz Extracelular/genética , Proteínas de la Matriz Extracelular/metabolismo , Femenino , Ácido Litocólico/farmacocinética , Ratones Endogámicos BALB C , Micelas , Neoplasias/fisiopatología , Tensoactivos/síntesis química , Tensoactivos/farmacocinética , Tensoactivos/uso terapéutico
13.
Mol Clin Oncol ; 13(5): 57, 2020 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-32953111

RESUMEN

Colorectal cancer (CRC) is a complex disease as shown by consensus classification. The present study attempted to identify subtypes with known prognostic markers for better clinical management. A total of 72 CRC tumors were examined for the expression of mismatch repair (MMR) proteins, along with caudal-type homeobox protein 2 (CDX2) and BRCA1, by immunohistochemistry. Tumors were assigned based on the presence or loss of MMR proteins as proficient or deficient. Correlations were examined with CDX2 and BRCA1 along with clinico-pathological features. Expressional pattern of microRNAs (miRs/miRNAs), such as miR-183-96-182, known to be associated with defective DNA damage repair were evaluated by reverse transcription-quantitative PCR. A total of 22% of the CRC tumors were assigned as deficient in mismatch repair. 71% of the tumors expressed CDX2 while only 21% had nuclear expression of BRCA1. Loss of CDX2 protein was higher in the deficient subtype compared with the proficient subtype. A total of 14% of the tumors had dual loss of MMR and BRCA1 proteins and showed aggressive clinical features in addition to elevated expression of DNA damage repair microRNAs. The present study shows the presence of a small proportion of colorectal tumors with dual loss of key proteins involved in DNA damage repair which may be amenable to specific therapy. The implication of the present observations warrants investigation in a larger patient cohort with prognostic information.

14.
Elife ; 92020 03 30.
Artículo en Inglés | MEDLINE | ID: mdl-32223892

RESUMEN

(Mtb) produces inflections in the host signaling networks to create a favorable milieu for survival. The virulent Mtb strain, Rv caused double strand breaks (DSBs), whereas the non-virulent Ra strain triggered single-stranded DNA generation. The effectors secreted by SecA2 pathway were essential and adequate for the genesis of DSBs. Accumulation of DSBs mediated through Rv activates ATM-Chk2 pathway of DNA damage response (DDR) signaling, resulting in altered cell cycle. Instead of the classical ATM-Chk2 DDR, Mtb gains survival advantage through ATM-Akt signaling cascade. Notably, in vivo infection with Mtb led to sustained DSBs and ATM activation during chronic phase of tuberculosis. Addition of ATM inhibitor enhances isoniazid mediated Mtb clearance in macrophages as well as in murine infection model, suggesting its utility for host directed adjunct therapy. Collectively, data suggests that DSBs inflicted by SecA2 secretome of Mtb provides survival niche through activation of ATM kinase.


Asunto(s)
Adenosina Trifosfatasas/metabolismo , Proteínas Bacterianas/metabolismo , Roturas del ADN de Doble Cadena , Interacciones Huésped-Patógeno , Proteínas de Transporte de Membrana/metabolismo , Mycobacterium tuberculosis/patogenicidad , Transducción de Señal , Adenosina Trifosfatasas/genética , Animales , Proteínas de la Ataxia Telangiectasia Mutada/genética , Proteínas de la Ataxia Telangiectasia Mutada/metabolismo , Proteínas Bacterianas/genética , Femenino , Humanos , Pulmón/efectos de los fármacos , Pulmón/microbiología , Masculino , Proteínas de Transporte de Membrana/genética , Ratones , Ratones Endogámicos BALB C , Morfolinas/administración & dosificación , Mycobacterium tuberculosis/genética , Proteínas Proto-Oncogénicas c-akt/metabolismo , Pironas/administración & dosificación , Células RAW 264.7 , Bazo/efectos de los fármacos , Bazo/microbiología , Células THP-1 , Tuberculosis/microbiología
15.
ACS Cent Sci ; 5(10): 1648-1662, 2019 Oct 23.
Artículo en Inglés | MEDLINE | ID: mdl-31660434

RESUMEN

Rapid proliferation of cancer cells assisted by endothelial cell-mediated angiogenesis and acquired inflammation at the tumor microenvironment (TME) lowers the success rate of chemotherapeutic regimens. Therefore, targeting these processes using localized delivery of a minimally toxic drug combination may be a promising strategy. Here, we present engineering of a biocompatible self-assembled lithocholic acid-dipeptide derived hydrogel (TRI-Gel) that can maintain sustained delivery of antiproliferating doxorubicin, antiangiogenic combretastatin-A4 and anti-inflammatory dexamethasone. Application of TRI-Gel therapy to a murine tumor model promotes enhanced apoptosis with a concurrent reduction in angiogenesis and inflammation, leading to effective abrogation of tumor proliferation and increased median survival with reduced drug resistance. In-depth RNA-sequencing analysis showed that TRI-Gel therapy induced transcriptome-wide alternative splicing of many genes responsible for oncogenic transformation including sphingolipid genes. We demonstrate that TRI-Gel therapy targets the reversal of a unique intron retention event in ß-glucocerebrosidase 1 (Gba1), thereby increasing the availability of functional Gba1 protein. An enhanced Gba1 activity elevates ceramide levels responsible for apoptosis and decreases glucosylceramides to overcome drug resistance. Therefore, TRI-Gel therapy provides a unique system that affects the TME via post-transcriptional modulations of sphingolipid metabolic genes, thereby opening a new and rational approach to cancer therapy.

16.
J Biol Chem ; 294(36): 13224-13232, 2019 09 06.
Artículo en Inglés | MEDLINE | ID: mdl-31346036

RESUMEN

The gene encoding the tumor suppressor p53 is mutated in most cancers. p53 expression is known to be tightly controlled by several E3 ligases. Here, we show that F-box and WD repeat domain-containing 7α (FBW7α), the substrate-recognition component of the SCFFBW7 multiprotein E3 ligase complex, targets both WT and tumor-derived mutants of p53 for proteasomal degradation in multiple human cancer cell lines (HCT116 and U2OS). We found that lack of FBW7α stabilizes p53 levels, thereby increasing its half-life. p53 ubiquitylation and subsequent degradation require the F-box and the C-terminal WD40 repeats in FBW7α. The polyubiquitylation of p53 occurred via Lys-48 linkage and involved phosphorylation on p53 at Ser-33 and Ser-37 by glycogen synthase kinase 3ß (GSK3ß) and DNA-dependent protein kinase (DNA-PK), respectively. These phosphorylation events created a phosphodegron that enhanced p53 binding to FBW7α, allowing for the attachment of polyubiquitin moieties at Lys-132 in p53. FBW7α-dependent p53 polyubiquitylation apparently occurred during and immediately after DNA double-strand breaks induced by either doxorubicin or ionizing radiation. Accordingly, in cells lacking FBW7α, p53 induction was enhanced after DNA damage. Phosphodegron-mediated polyubiquitylation of p53 on Lys-132 had functional consequences, with cells in which FBW7α-mediated p53 degradation was abrogated exhibiting enhancement of their tumorigenic potential. We conclude that p53, which previously has been reported to transactivate FBW7, is also targeted by the same E3 ligase for degradation, suggesting the presence of a regulatory feedback loop that controls p53 levels and functions during DNA damage.


Asunto(s)
Proteína 7 que Contiene Repeticiones F-Box-WD/metabolismo , Proteína p53 Supresora de Tumor/metabolismo , Células HCT116 , Humanos , Mutación , Fosforilación , Proteína p53 Supresora de Tumor/genética , Ubiquitinación
17.
Cell Rep ; 24(4): 947-961.e7, 2018 07 24.
Artículo en Inglés | MEDLINE | ID: mdl-30044990

RESUMEN

Mutations in BLM helicase predispose Bloom syndrome (BS) patients to a wide spectrum of cancers. We demonstrate that MIB1-ubiquitylated BLM in G1 phase functions as an adaptor protein by enhancing the binding of transcription factor c-Jun and its E3 ligase, Fbw7α. BLM enhances the K48/K63-linked ubiquitylation on c-Jun, thereby enhancing the rate of its subsequent degradation. Functionally defective Fbw7α mutants prevalent in multiple human cancers are reactivated by BLM. However, BS patient-derived BLM mutants cannot potentiate Fbw7α-dependent c-Jun degradation. The decrease in the levels of c-Jun in cells expressing BLM prevents effective c-Jun binding to 2,584 gene promoters. This causes decreases in the transcript and protein levels of c-Jun targets in BLM-expressing cells, resulting in attenuated c-Jun-dependent effects during neoplastic transformation. Thus, BLM carries out its function as a tumor suppressor by enhancing c-Jun turnover and thereby preventing its activity as a proto-oncogene.


Asunto(s)
Proteína 7 que Contiene Repeticiones F-Box-WD/metabolismo , Genes jun , Proteínas Proto-Oncogénicas c-jun/metabolismo , RecQ Helicasas/metabolismo , Animales , Síndrome de Bloom/genética , Síndrome de Bloom/metabolismo , Carcinogénesis , Proteína 7 que Contiene Repeticiones F-Box-WD/genética , Fase G1 , Células HCT116 , Células HEK293 , Humanos , Ratones , Ratones Desnudos , Mutación , Proto-Oncogenes Mas , Proteínas Proto-Oncogénicas c-jun/genética , RecQ Helicasas/genética , Ubiquitinación
18.
Nat Commun ; 9(1): 1016, 2018 03 09.
Artículo en Inglés | MEDLINE | ID: mdl-29523790

RESUMEN

Mutations in BLM in Bloom Syndrome patients predispose them to multiple types of cancers. Here we report that BLM is recruited in a biphasic manner to annotated DSBs. BLM recruitment is dependent on the presence of NBS1, MRE11 and ATM. While ATM activity is essential for BLM recruitment in early phase, it is dispensable in late phase when MRE11 exonuclease activity and RNF8-mediated ubiquitylation of BLM are the key determinants. Interaction between polyubiquitylated BLM and NBS1 is essential for the helicase to be retained at the DSBs. The helicase activity of BLM is required for the recruitment of HR and c-NHEJ factors onto the chromatin in S- and G1-phase, respectively. During the repair phase, BLM inhibits HR in S-phase and c-NHEJ in G1-phase. Consequently, inhibition of helicase activity of BLM enhances the rate of DNA alterations. Thus BLM utilizes its pro- and anti-repair functions to maintain genome stability.


Asunto(s)
Proteínas Portadoras/metabolismo , Roturas del ADN de Doble Cadena , Reparación del ADN por Unión de Extremidades/genética , Recombinación Homóloga/genética , Proteínas Nucleares/metabolismo , RecQ Helicasas/metabolismo , Proteínas de la Ataxia Telangiectasia Mutada/metabolismo , Síndrome de Bloom/genética , Ciclo Celular/genética , Proteínas de Ciclo Celular/metabolismo , Línea Celular , Proteínas de Unión al ADN/metabolismo , Inestabilidad Genómica/genética , Células HEK293 , Humanos , Proteína Homóloga de MRE11/metabolismo , Recombinasa Rad51/metabolismo , RecQ Helicasas/genética , Ubiquitina-Proteína Ligasas/metabolismo , Ubiquitinación
19.
Bioconjug Chem ; 28(12): 2942-2953, 2017 Dec 20.
Artículo en Inglés | MEDLINE | ID: mdl-29083862

RESUMEN

Weakly basic drugs display poor solubility and tend to precipitate in the stomach's acidic environment causing reduced oral bioavailability. Tracing of these orally delivered therapeutic agents using molecular probes is challenged due to their poor absorption in the gastrointestinal tract (GIT). Therefore, we designed a gastric pH stable bile acid derived amphiphile where Tamoxifen (as a model anticancer drug) is conjugated to lithocholic acid derived phospholipid (LCA-Tam-PC). In vitro studies suggested the selective nature of LCA-Tam-PC for cancer cells over normal cells as compared to the parent drug. Fluorescent labeled version of the conjugate (LCA-Tam-NBD-PC) displayed an increased intracellular uptake compared to Tamoxifen. We then investigated the antitumor potential, toxicity, and median survival in 4T1 tumor bearing BALB/c mice upon LCA-Tam-PC treatment. Our studies confirmed a significant reduction in the tumor volume, tumor weight, and reduced hepatotoxicity with a significant increase in median survival on LCA-Tam-PC treatment as compared to the parent drug. Pharmacokinetic and biodistribution studies using LCA-Tam-NBD-PC witnessed the enhanced gut absorption, blood circulation, and tumor site accumulation of phospholipid-drug conjugate leading to improved antitumor activity. Therefore, our studies revealed that conjugation of chemotherapeutic/imaging agents to bile acid phospholipid can provide a new platform for oral delivery and tracing of chemotherapeutic drugs.


Asunto(s)
Antineoplásicos/química , Antineoplásicos/farmacocinética , Diagnóstico por Imagen/métodos , Ácido Litocólico/química , Hígado/efectos de los fármacos , Fosfolípidos/química , Animales , Antineoplásicos/farmacología , Antineoplásicos/toxicidad , Disponibilidad Biológica , Humanos , Interacciones Hidrofóbicas e Hidrofílicas , Células MCF-7 , Ratones , Ratones Endogámicos BALB C , Tamoxifeno/química , Tamoxifeno/farmacocinética , Tamoxifeno/farmacología , Tamoxifeno/toxicidad , Distribución Tisular
20.
Mol Pharm ; 14(8): 2649-2659, 2017 08 07.
Artículo en Inglés | MEDLINE | ID: mdl-28665132

RESUMEN

Lipid composition in general determines the drug encapsulation efficacy and release kinetics from liposomes that impact the clinical outcomes of cancer therapy. We synthesized three bile acid phospholipids by conjugating the phosphocholine headgroup to the 3'-hydroxyl group of benzylated lithocholic acid (LCA), deoxycholic acid (DCA), and cholic acid (CA); and investigated the impact of membrane rigidity on drug encapsulation efficacy, drug release kinetics, anticancer effects, and mice survival. Liposomes with a hydrodynamic diameter of 100-110 nm were subsequently developed using these phospholipids. Fluorescence-probe based quantification revealed a more fluidic nature of DCA-PC- and CA-PC-derived liposomes, whereas the LCA-PC-derived ones are rigid in nature. Doxorubicin encapsulation studies showed ∼75% encapsulation and ∼38% entrapment efficacy of doxorubicin using more fluidic DCA-PC and CA-PC derived liposomes as compared to ∼58% encapsulation and ∼18% entrapment efficacy in the case of LCA-PC derived liposomes. In vivo anticancer studies in the murine model confirmed that doxorubicin entrapped CA-PC liposomes compromise mice survival, whereas rigid drug entrapped LCA-PC-derived-liposomes increased mice survival with ∼2-fold decrease in tumor volume. Pharmacokinetic and biodistribution studies revealed an ∼1.5-fold increase in plasma drug concentration and an ∼4.0-fold rise in tumor accumulation of doxorubicin on treatment with drug entrapped LCA-PC liposomes as compared to doxorubicin alone. In summary, this study presents the impact of bile acid derived liposomes with different rigidities on drug delivery and mice survivability.


Asunto(s)
Ácidos y Sales Biliares/química , Doxorrubicina/química , Fosfolípidos/química , Animales , Ácido Cólico/química , Ácido Desoxicólico/química , Portadores de Fármacos/química , Ácido Litocólico/química , Ratones
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