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Abstract
This article reviews the discovery of PCSK9, its structure-function characteristics, and its presently known and proposed novel biological functions. The major critical function of PCSK9 deduced from human and mouse studies, as well as cellular and structural analyses, is its role in increasing the levels of circulating low-density lipoprotein (LDL)-cholesterol (LDLc), via its ability to enhance the sorting and escort of the cell surface LDL receptor (LDLR) to lysosomes. This implicates the binding of the catalytic domain of PCSK9 to the EGF-A domain of the LDLR. This also requires the presence of the C-terminal Cys/His-rich domain, its binding to the secreted cytosolic cyclase associated protein 1, and possibly another membrane-bound "protein X". Curiously, in PCSK9-deficient mice, an alternative to the downregulation of the surface levels of the LDLR by PCSK9 is taking place in the liver of female mice in a 17β-estradiol-dependent manner by still an unknown mechanism. Recent studies have extended our understanding of the biological functions of PCSK9, namely its implication in septic shock, vascular inflammation, viral infections (Dengue; SARS-CoV-2) or immune checkpoint modulation in cancer via the regulation of the cell surface levels of the T-cell receptor and MHC-I, which govern the antitumoral activity of CD8+ T cells. Because PCSK9 inhibition may be advantageous in these processes, the availability of injectable safe PCSK9 inhibitors that reduces by 50% to 60% LDLc above the effect of statins is highly valuable. Indeed, injectable PCSK9 monoclonal antibody or small interfering RNA could be added to current immunotherapies in cancer/metastasis.
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Affiliation(s)
- Nabil G Seidah
- Laboratory of Biochemical Neuroendocrinology, Montreal Clinical Research Institute (IRCM, affiliated to the University of Montreal), Montreal, QC, Canada
| | - Annik Prat
- Laboratory of Biochemical Neuroendocrinology, Montreal Clinical Research Institute (IRCM, affiliated to the University of Montreal), Montreal, QC, Canada
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RhoGTPases - A novel link between cytoskeleton organization and cisplatin resistance. Drug Resist Updat 2015; 19:22-32. [PMID: 25660168 DOI: 10.1016/j.drup.2015.01.001] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2014] [Revised: 01/13/2015] [Accepted: 01/18/2015] [Indexed: 12/11/2022]
Abstract
For more than three decades, platinum compounds have been the first line treatment for a wide spectrum of solid tumors. Yet, cisplatin resistance is a major impediment in cancer therapy, and deciphering the mechanisms underlying chemoresistance is crucial for the development of novel therapies with enhanced efficacy. The Rho subfamily of small GTPases plays a significant role in cancer progression, and a growing body of evidence points toward the involvement of these proteins in anticancer drug resistance, including cisplatin resistance. The cycling between active and inactive states, governed by the balance between their GEFs, GAPs and GDIs, RhoGTPases, acts as molecular switches with a pivotal role in actin cytoskeleton organization. The Rho subfamily of proteins is involved in many key cellular processes including adhesion, vesicular trafficking, proliferation, survival, cell morphology and cell-matrix interactions. Although RhoA, RhoB and RhoC are highly homologous and share some upstream regulators and downstream effectors, they each have different roles in cancer progression and chemoresistance. While RhoA and RhoC are upregulated in many tumors and can stimulate transformation, RhoB appears to exhibit tumor suppressor characteristics with proapoptotic effects. In the current review, we discuss the role of Rho subfamily of proteins in cancer, and focus on their involvement in intrinsic and acquired drug resistance.
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Palsuledesai CC, Ochocki JD, Markowski TW, Distefano MD. A combination of metabolic labeling and 2D-DIGE analysis in response to a farnesyltransferase inhibitor facilitates the discovery of new prenylated proteins. MOLECULAR BIOSYSTEMS 2014; 10:1094-103. [PMID: 24577581 DOI: 10.1039/c3mb70593e] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Protein prenylation is a post-translational modification required for proper cellular localization and activity of many important eukaryotic proteins. Farnesyltransferase inhibitors (FTIs) have been explored extensively for their antitumor activity. To assist in identifying potentially new and more useful markers for therapeutic applications, we developed a strategy that uses a combination of metabolic labeling and 2D DIGE (differential gel electrophoresis) to discover new prenylated proteins whose cellular levels are influenced by FTIs. In this approach, metabolic labeling of prenylated proteins was first carried out with an alkyne-modified isoprenoid analog, C15Alk, in the presence or absence of the FTI L-744,832. The resulting alkyne-tagged proteins were then labeled with Cy3-N3 and Cy5-N3 and subjected to 2D-DIGE. Multiple spots having altered levels of labeling in presence of the FTI were observed. Mass spectrometric analysis of some of the differentially labeled spots identified several known prenylated proteins, along with HisRS, PACN-3, GNAI-1 and GNAI-2, which are not known to be prenylated. In vitro farnesylation of a C-terminal peptide sequence derived from GNAI-1 and GNAI-2 produced a farnesylated product, suggesting GNAI-1 and GNAI-2 are potential novel farnesylated proteins. These results suggest that this new strategy could be useful for the identification of prenylated proteins whose level of post-translational modification has been modulated by the presence of an FTI. Additionally, this approach, which decreases sample complexity and thereby facilitates analysis, should be applicable to studies of other post-translational modifications as well.
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Anbu S, Killivalavan A, Alegria EC, Mathan G, Kandaswamy M. Effect of 1,10-phenanthroline on DNA binding, DNA cleavage, cytotoxic and lactate dehydrogenase inhibition properties of Robson type macrocyclic dicopper(II) complex. J COORD CHEM 2013. [DOI: 10.1080/00958972.2013.858136] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Affiliation(s)
- Sellamuthu Anbu
- Department of Inorganic Chemistry, School of Chemical Sciences, University of Madras, Guindy Maraimalai Campus, Chennai, India
| | - Asaithambi Killivalavan
- Department of Biomedical Science, School of Basic Medical Sciences, Bharathidasan University, Tiruchirapalli, India
| | - Elisabete C.B.A. Alegria
- Chemical Engineering Departmental Area, ISEL, Lisboa, Portugal
- Centro de Química Estrutural, Complexo I, Instituto Superior Técnico, Technical University of Lisbon, Lisboa, Portugal
| | - Ganeshan Mathan
- Department of Biomedical Science, School of Basic Medical Sciences, Bharathidasan University, Tiruchirapalli, India
| | - Muthusamy Kandaswamy
- Department of Inorganic Chemistry, School of Chemical Sciences, University of Madras, Guindy Maraimalai Campus, Chennai, India
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Yang G, Mercado-Uribe I, Multani AS, Sen S, Shih IM, Wong KK, Gershenson DM, Liu J. RAS promotes tumorigenesis through genomic instability induced by imbalanced expression of Aurora-A and BRCA2 in midbody during cytokinesis. Int J Cancer 2013; 133:275-85. [PMID: 23319376 PMCID: PMC3883442 DOI: 10.1002/ijc.28032] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2012] [Accepted: 12/21/2012] [Indexed: 12/31/2022]
Abstract
The oncogene RAS is known to induce genomic instability, leading to cancer development; the underlying mechanism, however, remains poorly understood. To better understand how RAS functions, we measured the activity of the functionally related genes Aurora-A and BRCA2 in ovarian cancer cell lines and tumor samples containing RAS mutations. We found that Aurora-A and BRCA2 inversely controlled RAS-associated genomic instability and ovarian tumorigenesis through regulation of cytokinesis and polyploidization. Overexpression of mutated RAS ablated BRCA2 expression but induced Aurora-A accumulation at the midbody, leading to abnormal cytokinesis and ultimately chromosomal instability via polyploidy in cancer cells. RAS regulates the expression of Aurora-A and BRCA2 through dysregulated protein expression of farnesyl protein transferase β and insulin-like growth factor binding protein 3. Our results suggest that the imbalance in expression of Aurora-A and BRCA2 regulates RAS-induced genomic instability and tumorigenesis.
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Affiliation(s)
- Gong Yang
- Cancer Research Laboratory, Fudan University Shanghai Cancer Center; Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, 200032 China
- Department of Pathology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Imelda Mercado-Uribe
- Department of Pathology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Asha S. Multani
- Department of Genetics, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Subrata Sen
- Department of Molecular Pathology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Ie-Ming Shih
- Department of Gynecologic Pathology, School of Medicine, The Johns Hopkins University, Baltimore, MD 21209, USA
| | - Kwong-Kwok Wong
- Department of Gynecological Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - David M Gershenson
- Department of Gynecological Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Jinsong Liu
- Department of Pathology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
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Ras signaling contributes to survival of human T-cell leukemia/lymphoma virus type 1 (HTLV-1) Tax-positive T-cells. Apoptosis 2012; 17:219-28. [PMID: 22127644 PMCID: PMC3279637 DOI: 10.1007/s10495-011-0676-z] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Ras signaling pathways play an important role in cellular proliferation and survival, and inappropriate activation of Ras frequently results in cell transformation and cancer. Human T-cell leukemia/lymphoma virus type 1 (HTLV-1) is the etiological agent of the adult T-cell leukemia/lymphoma (ATLL), a severe malignancy that has a poor prognosis and exhibits resistance to conventional chemotherapy. Although the mechanisms involved in cell transformation by HTLV-1 have not been completely clarified, it is generally thought that Tax plays a pivotal role in the process. We have previously proposed that a functionally active Ras protein is needed for efficient anti-apoptotic activity of Tax. In this study we report data indicating that the apoptotic resistance of cells expressing Tax, constitutively or transiently, is linked to the intracellular levels of Ras-GTP. Indeed, we found that Tax-positive cells have a high content of active Ras, and that inhibition of Ras signaling, using the antagonist farnesyl thyosalicylic acid (FTS), increases their sensitivity to apoptosis. FTS treatment was also accompanied by a decrease in ERK, but not Akt, phosphorylation. Thus, all together our data suggest that the interaction between Tax and Ras could be important to ATLL pathogenesis, and indicate Ras as a possible target for therapeutic intervention in ATLL patients.
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Anbu S, Ravishankaran R, Karande AA, Kandaswamy M. DNA targeting polyaza macrobicyclic dizinc(ii) complexes promoting high in vitro caspase dependent anti-proliferative activity against human carcinoma cancer cells. Dalton Trans 2012; 41:12970-83. [DOI: 10.1039/c2dt31094e] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Anbu S, Shanmugaraju S, Ravishankaran R, Karande AA, Mukherjee PS. Naphthylhydrazone based selective and sensitive chemosensors for Cu2+ and their application in bioimaging. Dalton Trans 2012; 41:13330-7. [DOI: 10.1039/c2dt31335a] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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