PLK4 is upregulated in prostate cancer and its inhibition reduces centrosome amplification and causes senescence.

BACKGROUND: Identification of novel molecular target(s) is important for designing newer mechanistically driven approaches for the treatment of prostate cancer (PCa), which is one of the main causes of morbidity and mortality in men. In this study, we determined the role of polo-like kinase 4 (PLK4), which regulates centriole duplication and centrosome amplification (CA), in PCa. MATERIALS AND METHODS: Employing human PCa tissue microarrays, we assessed the prevalence of CA, correlated with Gleason score, and estimated major causes of CA in PCa (cell doubling vs. centriole overduplication) by staining for mother/mature centrioles. We also assessed PLK4 expression and correlated it with CA in human PCa tissues and cell lines. Further, we determined the effects of PLK4 inhibition in human PCa cells. RESULTS: Compared to benign prostate, human PCa demonstrated significantly higher CA, which was also positively correlated with the Gleason score. Further, most cases of CA were found to arise by centriole overduplication rather than cell doubling events (e.g., cytokinesis failure) in PCa. In addition, PLK4 was overexpressed in human PCa cell lines and tumors. Moreover, PLK4 inhibitors CFI-400945 and centrinone-B inhibited cell growth, viability, and colony formation of both androgen-responsive and androgen-independent PCa cell lines. PLK4 inhibition also induced cell cycle arrest and senescence in human PCa cells. CONCLUSIONS: CA is prevalent in PCa and arises predominantly by centriole overduplication as opposed to cell doubling events. Loss of centrioles is cellular stress that can promote senescence and suggests that PLK4 inhibition may be a viable therapeutic strategy in PCa.

Frizzled receptors in melanomagenesis: From molecular interactions to target identification.

Frizzled (FZD) proteins are receptors for the WNT family ligands. Inherited human diseases and genetic experiments using knockout mice have revealed a central role of FZDs in multiple aspects of embryonic development and tissue homeostasis. Misregulated FZD signaling has also been found in many cancers. Recent studies on three out of the ten mammalian FZDs in melanoma have shown that they promote tumor cell proliferation and invasion, via the activation of the canonical WNT/ß-catenin or non-canonical PCP signaling pathway. In this concise review, we summarize our current knowledge of individual FZDs in melanoma, discuss the involvement of both the canonical and non-canonical pathways, and describe ongoing efforts to target the FZD receptors for melanoma treatment.

Genetic Manipulation of Sirtuin 3 Causes Alterations of Key Metabolic Regulators in Melanoma.

The mitochondrial sirtuin SIRT3 plays key roles in cellular metabolism and energy production, which makes it an obvious target for the management of cancer, including melanoma. Previously, we have demonstrated that SIRT3 was constitutively upregulated in human melanoma and its inhibition resulted in anti-proliferative effects in vitro in human melanoma cells and in vivo in human melanoma xenografts. In this study, we expanded our data employing knockdown and overexpression strategies in cell culture and mouse xenografts to further validate and establish the pro-proliferative function of SIRT3 in melanocytic cells, and its associated potential mechanisms, especially focusing on the metabolic regulation. We found that short-hairpin RNA (shRNA) mediated SIRT3 knockdown in G361 melanoma cells showed diminished tumorigenesis in immunodeficient Nu/Nu mice. Conversely, SIRT3 overexpressing Hs294T melanoma cells showed increased tumor growth. These effects were consistent with changes in markers of proliferation (PCNA), survival (Survivin) and angiogenesis (VEGF) in xenografted tissues. Further, in in vitro culture system, we determined the effect of SIRT3 knockdown on glucose metabolism in SK-MEL-2 cells, using a PCR array. SIRT3 knockdown caused alterations in a total of 37 genes involved in the regulation and enzymatic pathways of glucose (32 genes) and glycogen (5 genes) metabolism. Functions annotation of these identified genes, using the ingenuity pathway analysis (IPA), predicted cumulative actions of decreased cell viability/proliferation, tumor growth and reactive oxygen species (ROS), and increased apoptosis in response to SIRT3 knockdown. Further, IPA gene network analysis of SIRT3 modulated genes revealed the interactions among these genes in addition to several melanoma-associated genes. Sirtuin pathway was identified as one of the top canonical pathways showing the interaction of SIRT3 with metabolic regulatory genes along with other sirtuins. IPA analysis also predicted the inhibition of HIF1α, PKM, KDM8, PPARGC1A, mTOR, and activation of P53 and CLPP; the genes involved in major cancer/melanoma-associated signaling events. Collectively, these results suggest that SIRT3 inhibition affects cellular metabolism, to impart an anti-proliferative response against melanoma.

4'-Bromo-resveratrol, a dual Sirtuin-1 and Sirtuin-3 inhibitor, inhibits melanoma cell growth through mitochondrial metabolic reprogramming.

Sirtuin-1 and -3 (SIRT1 and SIRT3) are important nicotinamide adenine dinucleotide (NAD+ )-dependent deacetylases known to regulate a variety of cellular functions. Studies have shown that SIRT1 and SIRT3 were overexpressed in human melanoma cells and tissues and their inhibition resulted in a significant antiproliferative response in human melanoma cells and antitumor response in a mouse xenograft model of melanoma. In this study, we determined the antiproliferative efficacy of a newly identified dual small molecule inhibitor of SIRT1 and SIRT3, 4'-bromo-resveratrol (4'-BR), in human melanoma cell lines (G361, SK-MEL-28, and SK-MEL-2). Our data demonstrate that 4'-BR treatment of melanoma cells resulted in (a) decrease in proliferation and clonogenic survival; (b) induction of apoptosis accompanied by a decrease in procaspase-3, procaspase-8, and increase in the cleavage of caspase-3 and poly (ADP-ribose) polymerase (PARP); (c) marked downregulation of proliferating cell nuclear antigen (PCNA); and (d) inhibition of melanoma cell migration. Further, 4'-BR caused a G0/G1 phase arrest of melanoma cells that was accompanied by an increase in WAF-1/P21 and decrease in Cyclin D1/Cyclin-dependent kinase 6 protein levels. Furthermore, we found that 4'-BR causes a decrease in lactate production, glucose uptake, and NAD+ /NADH ratio. These responses were accompanied by downregulation in lactate dehydrogenase A and glucose transporter 1 in melanoma cells. Collectively, our data suggest that dual inhibition of SIRT1 and SIRT3 using 4'-BR imparted antiproliferative effects in melanoma cells through a metabolic reprogramming and affecting the cell cycle and apoptosis signaling. Therefore, concomitant pharmacological inhibition of SIRT1 and SIRT3 needs further investigation for melanoma management.

Centriole Overduplication is the Predominant Mechanism Leading to Centrosome Amplification in Melanoma.

Centrosome amplification (CA) is common in cancer and can arise by centriole overduplication or by cell doubling events, including the failure of cell division and cell-cell fusion. To assess the relative contributions of these two mechanisms, the number of centrosomes with mature/mother centrioles was examined by immunofluorescence in a tissue microarray of human melanomas and benign nevi (n = 79 and 17, respectively). The centrosomal protein 170 (CEP170) was used to identify centrosomes with mature centrioles; this is expected to be present in most centrosomes with cell doubling, but on fewer centrosomes with overduplication. Using this method, it was determined that the majority of CA in melanoma can be attributed to centriole overduplication rather than cell doubling events. As Polo-like kinase 4 (PLK4) is the master regulator of centriole duplication, the hypothesis that PLK4 overexpression contributes to centriole overduplication was evaluated. PLK4 is significantly overexpressed in melanoma compared with benign nevi and in a panel of human melanoma cell lines (A375, Hs294T, G361, WM35, WM115, 451Lu, and SK-MEL-28) compared with normal human melanocytes. Interestingly, although PLK4 expression did not correlate with CA in most cases, treatment of melanoma cells with a selective small-molecule PLK4 inhibitor (centrinone B) significantly decreased cell proliferation. The antiproliferative effects of centrinone B were also accompanied by induction of apoptosis.Implications: This study demonstrates that centriole overduplication is the predominant mechanism leading to centrosome amplification in melanoma and that PLK4 should be further evaluated as a potential therapeutic target for melanoma treatment. Mol Cancer Res; 16(3); 517-27. ©2018 AACR.

Histone Deacetylase Inhibitory Approaches for the Management of Osteoarthritis.

This commentary highlights the article by Makki and Haqqi that proposes the use of vorinostat as a therapeutic agent for the management of osteoarthritis.

c-CBL regulates melanoma proliferation, migration, invasion and the FAK-SRC-GRB2 nexus.

Melanoma is one of the most aggressive and lethal forms of skin cancer. Despite recent improvements in targeted therapies, many patients with advanced disease fail to achieve lasting tumor regression. Therefore, it is important to develop novel druggable targets that can be exploited to improve clinical outcome. Here, we studied the role of Casitas B-lineage lymphoma (c-CBL), an E3 ubiquitin ligase, in human melanoma. Employing quantitative real-time PCR and Western blot analysis in a panel of human melanoma cell lines (A375, G361, Hs-294T, SK-Mel-2, SK-Mel-28 and 451Lu), we found that c-CBL is strongly expressed in human melanoma cells at the mRNA and protein levels. Further, we determined c-CBL levels in clinical samples of melanomas and benign melanocytic nevi, using quantitative Nuance multispectral imaging. Compared to benign nevi, melanomas showed an overlapping range of c-CBL immunoreactivity. Small interfering RNA (siRNA)-mediated knockdown of c-CBL resulted in decreased proliferation, clonogenic survival and migration of melanoma cells. Furthermore, it also resulted in decreased cellular invasion in a 3D spheroid assay system. C-CBL and FAK are regulated by SRC, and FAK binds SRC and GRB2. C-CBL E3 ligase domain regulates receptor tyrosine kinase internalization through ubiquitination and its ring finger domain stabilizes the FAK-SRC-actin cytoskeleton thereby promoting cellular motility. C-CBL knockdown was associated with decreased protein and/or mRNA levels of SRC, FAK and GRB2. Taken together, we have provided evidence that c-CBL plays a role in melanoma cell proliferation, migration and invasion as well as inhibition of the FAK-GRB2-SRC nexus. Our findings indicate that additional studies are warranted to further dissect the role of c-CBL in melanoma and determine the therapeutic potential of its inhibition.

Pro-Proliferative Function of Mitochondrial Sirtuin Deacetylase SIRT3 in Human Melanoma.

Melanoma, the most aggressive form of skin cancer, is often fatal if not treated early. Therefore, novel target-based strategies are required to combat this neoplasm. The objective of this study was to determine the role and functional significance of the mitochondrial sirtuin 3 (SIRT3) in melanoma. We found that compared with normal primary and immortalized human melanocytes, SIRT3 is significantly overexpressed in multiple human melanoma cells at mRNA and protein levels. Further, employing human tissue microarray, we found that SIRT3 is significantly upregulated in clinical melanoma tissues, compared with melanocytic nevi tissues. Furthermore, a short hairpin RNA-mediated knockdown of SIRT3 in human melanoma cells resulted in (i) a decrease in cellular proliferation, colony formation, and cellular migration; (ii) induction of senescence as shown by an increase in senescence-associated beta-galactosidase activity and formation of senescence-associated heterochromatin foci as well as an increase in mRNA and protein levels of p16(INK4a) and p21(Waf1); (iii) G1-phase arrest of the cell cycle; and (iv) decreases in mRNA and protein levels of cyclins (D1, E1) and cyclin-dependent kinases (2, 4, and 6). Conversely, forced exogenous overexpression of SIRT3 promoted an increase in proliferative potential of Hs294T melanoma cells and normal immortalized Mel-ST melanocytes. Finally, we found that SIRT3 knockdown significantly inhibited tumorigenesis in a xenograft model in vivo. To our knowledge, this is the first study supporting the pro-proliferative function of SIRT3 in melanoma.

Molecular signatures of sanguinarine in human pancreatic cancer cells: A large scale label-free comparative proteomics approach.

Pancreatic cancer remains one of the most lethal of all human malignancies with its incidence nearly equaling its mortality rate. Therefore, it's crucial to identify newer mechanism-based agents and targets to effectively manage pancreatic cancer. Plant-derived agents/drugs have historically been useful in cancer therapeutics. Sanguinarine is a plant alkaloid with anti-proliferative effects against cancers, including pancreatic cancer. This study was designed to determine the mechanism of sanguinarine's effects in pancreatic cancer with a hope to obtain useful information to improve the therapeutic options for the management of this neoplasm. We employed a quantitative proteomics approach to define the mechanism of sanguinarine's effects in human pancreatic cancer cells. Proteins from control and sanguinarine-treated pancreatic cancer cells were digested with trypsin, run by nano-LC/MS/MS, and identified with the help of Swiss-Prot database. Results from replicate injections were processed with the SIEVE software to identify proteins with differential expression. We identified 37 differentially expressed proteins (from a total of 3107), which are known to be involved in variety of cellular processes. Four of these proteins (IL33, CUL5, GPS1 and DUSP4) appear to occupy regulatory nodes in key pathways. Further validation by qRT-PCR and immunoblot analyses demonstrated that the dual specificity phosphatase-4 (DUSP4) was significantly upregulated by sanguinarine in BxPC-3 and MIA PaCa-2 cells. Sanguinarine treatment also caused down-regulation of HIF1α and PCNA, and increased cleavage of PARP and Caspase-7. Taken together, sanguinarine appears to have pleotropic effects, as it modulates multiple key signaling pathways, supporting the potential usefulness of sanguinarine against pancreatic cancer.

Sirtuin deacetylases: a new target for melanoma management.

Melanoma continues to cause more deaths than any other skin cancer, necessitating the development of new avenues of treatment. One promising new opportunity comes in the form of mechanism-based therapeutic targets. We recently reported the overexpression and delocalization of the class III histone deacetylase SIRT1 in melanoma, and demonstrated that its small molecule inhibition via Tenovin-1 decreased cell growth and viability of melanoma cells, possibly by a p53 mediated induction of p21. Here, we support our data using additional SIRT inhibitors, viz. Sirtinol and Ex-527, which suggests possible benefits of concomitantly inhibiting more than one Sirtuin for an effective cancer management strategy. This "Extra View" paper also includes a discussion of our results in the context of similar recent and concurrent studies. Furthermore, we expand upon our findings in an analysis of new research that may link the cellular localization and growth effects of SIRT1 with the PI3K signaling pathway.

Methaneseleninic acid and γ-Tocopherol combination inhibits prostate tumor growth in Vivo in a xenograft mouse model.

Studies have shown that vitamin E and selenium possess antiproliferative effects against prostate cancer (PCa). However, results from the Selenium and Vitamin E Cancer Prevention Trial (SELECT) suggest that vitamin E (α-tocopheryl acetate; 400 mg) and/or selenium (L-selenomethionine; 200 µg) were ineffective against PCa in humans. It is arguable that the selected dose/formulation of vitamin E/selenium were not optimal in SELECT. Thus, additional studies are needed to define the appropriate formulations/dose regimens of these agents. Here, we investigated the effect of methaneseleninic acid (MSA; 41 µg/kg) and/or γ-tocopherol (γT; 20.8 mg/kg or 41.7 mg/kg) in Nu/J mice implanted with 22Rν1 tumors. MSA (41 µg/kg) and γT (20.8 mg/kg) combination was most consistent in imparting anti-proliferative response; resulting in a significant decrease in i) tumor volume/weight, ii) serum PSA, and iii) Ki-67 immunostaining. Further, we observed i) an upregulation of pro-apoptosis Bax and a down-regulation of the pro-survival Bcl2, and ii) an increase in pro-apoptosis Bad. Furthermore, the combination resulted in a modulation of apolipoprotein E, selenoprotein P and Nrf2 in a fashion that favors antiproliferative responses. Overall, our study suggested that a combination of MSA and γT, at lower dose regimen, could be useful in PCa management.

Excellent anti-proliferative and pro-apoptotic effects of (-)-epigallocatechin-3-gallate encapsulated in chitosan nanoparticles on human melanoma cell growth both in vitro and in vivo.

Earlier we demonstrated the anti-proliferative and pro-apoptotic effects of green tea polyphenol epigallocatechin-3-gallate (EGCG) on human melanoma cells (Int J Cancer. 2005; 114(4): 513-21). The doses used in this study were not physiologically attainable and for chemoprevention the preferred route of administration is oral consumption. To overcome these shortcomings, and taking advantage of our novel concept of nanochemoprevention (Cancer Res. 2009;69(5):1712-6), we developed a nanotechnology based oral delivery system to encapsulate EGCG. Here, using human melanoma Mel 928 cells we demonstrate 8-fold dose advantage of this nanoformulation over native EGCG. Further, nano-EGCG treated cells showed marked induction of apoptosis and cell cycle inhibition along with the growth of Mel 928 tumor xenograft. Nano-EGCG also inhibited proliferation (Ki-67 and PCNA) and induced apoptosis (Bax, PARP) in tumors harvested from the treated mice. These observations warrant further in vivo efficacy studies of nano-EGCG in robust animal models of human melanoma. FROM THE CLINICAL EDITOR: This team of investigators developed a nanotechnology based oral delivery system to encapsulate EGCG, a green tea-derived polyphenol in chitosan nanoparticles. Using human melanoma cells, an eight-fold dose advantage was demonstrated over native EGCG, leading to measurable apoptosis induction and proliferation inhibition, warranting further in vivo investigations.

Methotrexate inhibits the viability of human melanoma cell lines and enhances Fas/Fas-ligand expression, apoptosis and response to interferon-alpha: rationale for its use in combination therapy.

Melanoma, a highly aggressive form of cancer, is notoriously resistant to available therapies. Methotrexate (MTX), an antifolate, competitively inhibits DNA synthesis and is effective for several types of cancer. In cutaneous T-cell lymphoma (CTCL), MTX increases Fas death receptor by decreasing Fas promoter methylation by blocking the synthesis of SAM, the principal methyl donor for DNMTs, resulting in enhanced Fas-mediated apoptosis. The objective of this study was to explore the effects of MTX in human melanoma. MTX variably inhibited the survival of melanoma cells and induced apoptosis as evident by annexin V positivity and senescence associated ß-galactosidase activity induction. Furthermore, MTX caused increased transcript and protein levels of extrinsic apoptotic pathway factors Fas and Fas-ligand, albeit at different levels in different cell lines. Our pyrosequencing studies showed that this increased expression of Fas was associated with Fas promoter demethylation. Overall, the ability of MTX to up-regulate Fas/FasL and enhance melanoma apoptosis through extrinsic as well as intrinsic pathways might make it a useful component of novel combination therapies designed to affect multiple melanoma targets simultaneously. In support of this concept, combination therapy with MTX and interferon-alpha (IFNα) induced significantly greater apoptosis in the aggressive A375 cell line than either agent alone.

Novel downstream molecular targets of SIRT1 in melanoma: a quantitative proteomics approach.

Melanoma is one of the most lethal forms of skin cancer and its incidence is continuing to rise in the United States. Therefore, novel mechanism and target-based strategies are needed for the management of this disease. SIRT1, a NAD(+)-dependent class III histone deacetylase, has been implicated in a variety of physiological processes and pathological conditions. We recently demonstrated that SIRT1 is upregulated in melanoma and its inhibition by a small-molecule, tenovin-1, inhibits cell proliferation and clonogenic survival of melanoma cells, possibly via activating p53. Here, we employed a gel free quantitative proteomics approach to identify the downstream effectors and targets of SIRT1 in melanoma. The human malignant melanoma, G361 cells were treated with tenovin-1 followed by protein extraction, in liquid trypsin digestion, and peptide analyses using nanoLC-MS/MS. A total of 1091 proteins were identified, of which 20 proteins showed significant differential expression with 95% confidence interval. These proteins were subjected to gene ontology and Ingenuity Pathway Analysis (IPA) to obtain the information regarding their biological and molecular functions. Real-Time qRT-PCR validation showed that five of these (PSAP, MYO1B, MOCOS, HIS1H4A and BUB3) were differentially expressed at mRNA levels. Based on their important role in cell cycle regulation, we selected to focus on BUB family proteins (BUB3, as well as BUB1 and BUBR1) for subsequent validation. The qRT-PCR and immunoblot analyses showed that tenovin-1 inhibition of SIRT1 resulted in a downregulation of BUB3, BUB1 and BUBR1 in multiple melanoma cell lines. Since tenovin-1 is an inhibitor of both SIRT1 and SIRT2, we employed lentivirus mediated silencing of SIRT1 and SIRT2 in G361 cells to determine if the observed effects on BUB family proteins are due to SIRT1- or SIRT2- inhibition. We found that only SIRT1 inhibition resulted in a decrease in BUB3, BUB1 and BUBR1. Our study identified the mitotic checkpoint regulator BUB family proteins as novel downstream targets of SIRT1. However, further validation is needed in appropriate models to confirm our findings and expand on our observations.

SIRT1 deacetylase is overexpressed in human melanoma and its small molecule inhibition imparts anti-proliferative response via p53 activation.

Melanoma causes more deaths than any other skin cancer, and its incidence in the US continues to rise. Current medical therapies are insufficient to control this deadly neoplasm, necessitating the development of new target-based approaches. The objective of this study was to determine the role and functional significance of the class III histone deacetylase SIRT1 in melanoma. We have found that SIRT1 is overexpressed in clinical human melanoma tissues and human melanoma cell lines (Sk-Mel-2, WM35, G361, A375, and Hs294T) compared to normal skin and normal melanocytes, respectively. In addition, treatment of melanoma cell lines A375, Hs294T, and G361 with Tenovin-1, a small molecule SIRT1 inhibitor, resulted in a significant decrease in cell growth and cell viability. Further, Tenovin-1 treatment also resulted in a marked decrease in the clonogenic survival of melanoma cells. Further experiments showed that the anti-proliferative response of Tenovin-1 was accompanied by an increase in the protein as well as activity of the tumor suppressor p53. This increase in p53 activity was substantiated by an increase in the protein level of its downstream target p21. Overall, these data suggest that small molecule inhibition of SIRT1 causes anti-proliferative effects in melanoma cells. SIRT1 appears to be acting through the activity of the tumor suppressor p53, which is not mutated in the majority of melanomas. However, future detailed studies are needed to further explore the role and mechanism of SIRT1 in melanoma development and progression and its usefulness in melanoma treatment.

Skin, reactive oxygen species, and circadian clocks.

SIGNIFICANCE: Skin, a complex organ and the body's first line of defense against environmental insults, plays a critical role in maintaining homeostasis in an organism. This balance is maintained through a complex network of cellular machinery and signaling events, including those regulating oxidative stress and circadian rhythms. These regulatory mechanisms have developed integral systems to protect skin cells and to signal to the rest of the body in the event of internal and environmental stresses. RECENT ADVANCES: Interestingly, several signaling pathways and many bioactive molecules have been found to be involved and even important in the regulation of oxidative stress and circadian rhythms, especially in the skin. It is becoming increasingly evident that these two regulatory systems may, in fact, be interconnected in the regulation of homeostasis. Important examples of molecules that connect the two systems include serotonin, melatonin, vitamin D, and vitamin A. CRITICAL ISSUES: Excessive reactive oxygen species and/or dysregulation of antioxidant system and circadian rhythms can cause critical errors in maintaining proper barrier function and skin health, as well as overall homeostasis. Unfortunately, the modern lifestyle seems to contribute to increasing alterations in redox balance and circadian rhythms, thereby posing a critical problem for normal functioning of the living system. FUTURE DIRECTIONS: Since the oxidative stress and circadian rhythm systems seem to have areas of overlap, future research needs to be focused on defining the interactions between these two important systems. This may be especially important in the skin where both systems play critical roles in protecting the whole body.

SIRT1 is upregulated in cutaneous T-cell lymphoma, and its inhibition induces growth arrest and apoptosis.

Silent information regulator type-1 (SIRT1) is the best-studied member of the Sirtuin (Sir2) family of nicotinamide dinucleotide (NAD)-dependent class III histone deacetylases (HDACs), but has not yet been explored in cutaneous T-cell lymphoma (CTCL). We analyzed five CTCL cell lines and lesional tissues using flow cytometry, immunostaining, immunoblotting, cell death, viability, and apoptosis assays, small-molecule inhibitors, and shRNA knockdown. We found strong SIRT1 expression among CTCL lines relative to normal lymphocytes. CTCL cells in lesional tissues also expressed SIRT1 strongly. SIRT1 knockdown resulted in reduced cellular metabolism and proliferation, increased apoptosis, and PARP cleavage products. Tenovin-1, which reversibly inhibits class III HDACs (SIRT1 and SIRT2), reduced SIRT enzymatic activity and SIRT1 expression and led to increased apoptosis. These alterations were accompanied by increased forkhead box O3 (FoxO3) in several cell lines and increased nuclear p53, as well as acetylated p53 in wtp53 MyLa CTCL line. A combination of class I/II and class III HDACIs (vorinostat and tenovin-1) produced significantly greater growth inhibition, cell death via apoptosis, as well as superior p53 promoter upregulation in wtp53 MyLa cells as compared with either agent alone. This occurred in a partially p53-dependent manner, as these effects were blunted by p53 knockdown. Our results indicate that SIRT1 is strongly expressed in CTCL. Its inhibition results in reduced growth and increased apoptosis of CTCL cells. Furthermore, our findings suggest that some CTCL patients, such as those with wtp53, might benefit more from treatment with a combination of different classes of HDACIs than with a single agent.

Aptamer-conjugated and doxorubicin-loaded unimolecular micelles for targeted therapy of prostate cancer.

In the absence of effective therapy for prostate cancer, there is an immense need for developing improved therapeutic options for the management of this disease. This study has demonstrated that aptamer-conjugated unimolecular micelles can improve the in vivo tumor biodistribution of systemically administered anti-cancer drugs in prostate cancer expressing prostate-specific membrane antigen (PSMA). The aptamer-conjugated unimolecular micelles were formed by individual hyperbranched polymer molecules consisting of a hyperbranched H40 polymer core and approximately 25 amphiphilic polylactide-poly(ethlyene glycol) (PLA-PEG) block copolymer arms (H40-PLA-PEG-Apt). The unimolecular micelles with an average hydrodynamic diameter of 69 nm exhibited a pH-sensitive and controlled drug release behavior. The targeted unimolecular micelles (i.e., DOX-loaded H40-PLA-PEG-Apt) exhibited a much higher cellular uptake in PSMA positive CWR22Rν1 prostate carcinoma cells than non-targeted unimolecular micelles (i.e., DOX-loaded H40-PLA-PEG), thereby leading to a significantly higher cytotoxicity. The DOX-loaded unimolecular micelles up-regulated the cleavage of PARP and Caspase 3 proteins and increased the protein expression of Bax along with a concomitant decrease in Bcl2. These micelles also increased the protein expression of cell cycle regulation marker P21 and P27. In CWR22Rν1 tumor-bearing mice, DOX-loaded H40-PLA-PEG-Apt micelles (i.e., targeted) also exhibited a much higher level of DOX accumulation in the tumor tissue than DOX-loaded H40-PLA-PEG micelles (i.e., non-targeted). These findings suggest that aptamer-conjugated unimolecular micelles may potentially be an effective drug nanocarrier to effectively treat prostate cancer.