| 1. |
- Aits, Sonja, et al.
(författare)
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HAMLET (human alpha-lactalbumin made lethal to tumor cells) triggers autophagic tumor cell death.
- 2009
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Ingår i: International Journal of Cancer. - : Wiley. - 0020-7136 .- 1097-0215. ; 124:5, s. 1008-1019
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Tidskriftsartikel (refereegranskat)abstract
- HAMLET, a complex of partially unfolded alpha-lactalbumin and oleic acid, kills a wide range of tumor cells. Here we propose that HAMLET causes macroautophagy in tumor cells and that this contributes to their death. Cell death was accompanied by mitochondrial damage and a reduction in the level of active mTOR and HAMLET triggered extensive cytoplasmic vacuolization and the formation of double-membrane-enclosed vesicles typical of macroautophagy. In addition, HAMLET caused a change from uniform (LC3-I) to granular (LC3-II) staining in LC3-GFP-transfected cells reflecting LC3 translocation during macroautophagy, and this was blocked by the macroautophagy inhibitor 3-methyladenine. HAMLET also caused accumulation of LC3-II detected by Western blot when lysosomal degradation was inhibited suggesting that HAMLET caused an increase in autophagic flux. To determine if macroautophagy contributed to cell death, we used RNA interference against Beclin-1 and Atg5. Suppression of Beclin-1 and Atg5 improved the survival of HAMLET-treated tumor cells and inhibited the increase in granular LC3-GFP staining. The results show that HAMLET triggers macroautophagy in tumor cells and suggest that macroautophagy contributes to HAMLET-induced tumor cell death.
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| 2. |
- Baldetorp, Bo, et al.
(författare)
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Reproducibility in DNA flow cytometric analysis of breast cancer: comparison of 12 laboratories' results for 67 sample homogenates
- 1995
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Ingår i: Cytometry. - : Wiley. - 0196-4763 .- 1097-0320. ; 22:2, s. 115-127
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Tidskriftsartikel (refereegranskat)abstract
- Flow cytometric (FCM) DNA analysis yields information on ploidy status and the S-phase fraction (SPF), variables of prognostic importance in breast cancer. The clinical value of the SPF is currently being evaluated in prospective randomized trials. The widespread use of FCM DNA analysis emphasizes the importance of reproducibility (both intra- and interlaboratory). In this study, 67 nuclear suspensions of breast cancer samples were analyzed by 12 laboratories routinely performing FCM DNA analysis in breast cancer. No general guidelines were imposed; each laboratory used its own standard protocols. For DNA ploidy status (diploid vs. non-diploid), agreement was complete for 79% (53/67) of the samples, compared with 64% (43/67) of samples when tetraploidy was considered [i.e., euploid (diploid+tetraploid) vs. aneuploid (the remaining non-diploid)]. For the SPF, pairwise comparison of the results of all 12 laboratories yielded a mean Spearman's rank correlation of 0.78 (range: 0.54-0.93). For those 39 samples being categorized in low or high SPF by all laboratories, all agreed in 14 samples (36%). Similar patterns were obtained with kappa measures, agreement being good for ploidy status (diploid vs. non-diploid; overall kappa = 0.87 and 0.74 for euploid vs. aneuploid), but moderate for the SPF [overall kappa = 0.47 (for low SPF vs. high SPF vs. "no SPF reported")]. Discrepancies were chiefly attributable to differences in the categorization of the S-phase values, rather than in FCM procedures, other critical differences being in the detection and interpretation of near-diploid and small non-diploid cell populations, the definition of tetraploidy, and the choice and execution of the method used for S-phase estimation. Based on the observations of this study, detailed guidelines for FCM analysis and interpretation of data are proposed in the Appendix. Some issues remain, however, e.g., to standardize a method for S-phase calculation and tetraploid definition.
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| 3. |
- Brest, Patrick, et al.
(författare)
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Histone deacetylase inhibitors promote the tumoricidal effect of HAMLET.
- 2007
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Ingår i: Cancer Research. - 1538-7445. ; 67:23, s. 11327-11334
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Tidskriftsartikel (refereegranskat)abstract
- Histone deacetylase inhibitors (HDIs) and HAMLET (human alpha-lactalbumin made lethal to tumor cells) interact with histones, modify the structure of chromatin, and trigger tumor cell death. This study investigated how the combination of HDIs and HAMLET influences cell viability, histone acetylation, and DNA integrity. The pretreatment of tumor cells with HDIs was shown to enhance the lethal effect of HAMLET and the histone hyperacetylation response to HDIs increased even further after HAMLET treatment. HDIs and HAMLET were shown to target different histone domains as HAMLET bound tailless core histones, whereas HDIs modify the acetylation of the histone tail. DNA damage in response to HAMLET was increased by HDIs. The DNA repair response (p21WAFI expression) was induced by both agonists but abolished when the two agonists were combined. The results suggest that the synergy of HDIs and HAMLET is based on different but converging death pathways, both involving chromatin alterations. We speculate that HAMLET and HDIs might be combined to promote tumor cell death in vivo.
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| 4. |
- Düringer, Caroline, et al.
(författare)
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HAMLET; a novel tool to identify apoptotic pathways in tumor cells.
- 2005
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Ingår i: Application of apoptosis to cancer treatment.. - Berlin/Heidelberg : Springer-Verlag. - 9781402033032 ; , s. 223-245
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Tumor cells often carry mutations in genes that control cell survival, and become resistant to signals that trigger cell death. Yet, some cell death pathways remain intact in tumor cells. If identified, these pathways might be exploited to selectively remove tumor cells. HAMLET (human α-lactalbumin made lethal to tumor cells) is a protein-lipid complex derived from human milk that activates cell death programs in tumor cells but not in healthy differentiated cells. We use HAMLET as a tool to identify apoptosis and apoptosis-like cell death mechanisms in tumor cells and to understand if these mechanisms differ between tumor and healthy cells. HAMLET interacts with the cell surface, translocates into the cytoplasm and accumulates in cell nuclei, where it disrupts the chromatin. Recent in vivo studies have shown that HAMLET maintains the tumoricidal activity in glioblastoma, papilloma and bladder cancer models, with no significant side effects. The results suggest that HAMLET should be explored as a new therapeutic agent with selectivity for the tumor and with little toxicity for adjacent healthy tissue. Such therapies are a much-needed complement to conventional treatments, to reduce the side effects and improve the selectivity.
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| 5. |
- Fischer, Walter, et al.
(författare)
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Human alpha-lactalbumin made lethal to tumor cells (HAMLET) kills human glioblastoma cells in brain xenografts by an apoptosis-like mechanism and prolongs survival.
- 2004
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Ingår i: Cancer Research. - 1538-7445. ; 64:6, s. 2105-2112
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Tidskriftsartikel (refereegranskat)abstract
- Malignant brain tumors present a major therapeutic challenge because no selective or efficient treatment is available. Here, we demonstrate that intratumoral administration of human α-lactalbumin made lethal to tumor cells (HAMLET) prolongs survival in a human glioblastoma (GBM) xenograft model, by selective induction of tumor cell apoptosis. HAMLET is a protein-lipid complex that is formed from α-lactalbumin when the protein changes its tertiary conformation and binds oleic acid as a cofactor. HAMLET induces apoptosis in a wide range of tumor cells in vitro, but the therapeutic effect in vivo has not been examined. In this study, invasively growing human GBM tumors were established in nude rats (Han:rnu/rnu Rowett, n = 20) by transplantation of human GBM biopsy spheroids. After 7 days, HAMLET was administered by intracerebral convection-enhanced delivery for 24 h into the tumor area; and α-lactalbumin, the native, folded variant of the same protein, was used as a control. HAMLET reduced the intracranial tumor volume and delayed the onset of pressure symptoms in the tumor-bearing rats. After 8 weeks, all α-lactalbumin-treated rats had developed pressure symptoms, but the HAMLET-treated rats remained asymptomatic. Magnetic resonance imaging scans revealed large differences in tumor volume (456 versus 63 mm3). HAMLET caused apoptosis in vivo in the tumor but not in adjacent intact brain tissue or in nontransformed human astrocytes, and no toxic side effects were observed. The results identify HAMLET as a new candidate in cancer therapy and suggest that HAMLET should be additionally explored as a novel approach to controlling GBM progression.
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| 6. |
- Gustafsson, Lotta, et al.
(författare)
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HAMLET kills tumor cells by apoptosis: Structure, cellular mechanisms, and therapy
- 2005
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Ingår i: Journal of Nutrition. - 1541-6100. ; 135:5, s. 1299-1303
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Tidskriftsartikel (refereegranskat)abstract
- New cancer treatments should aim to destroy tumor cells without disturbing normal tissue. HAMLET (human a-lactalbumin made lethal to tumor cells) offers a new molecular approach to solving this problem, because it induces apoptosis in tumor cells but leaves normal differentiated cells unaffected. After partial unfolding and binding to oleic acid, α-lactalbumin forms the HAMLET complex, which enters tumor cells and freezes their metabolic machinery. The cells proceed to fragment their DNA, and they disintegrate with apoptosis-like characteristics. HAMLET kills a wide range of malignant cells in vitro and maintains this activity in vivo in patients with skin papillomas. In addition, HAMLET has striking effects on human glioblastomas in a rat xenograft model. After convection-enhanced delivery, HAMLET diffuses throughout the brain, selectively killing tumor cells and controlling tumor progression without apparent tissue toxicity. HAMLET thus shows great promise as a new therapeutic with the advantage of selectivity for tumor cells and lack of toxicity.
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| 7. |
- Gustafsson, Lotta, et al.
(författare)
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Treatment of skin papillomas with topical alpha-lactalbumin-oleic acid
- 2004
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Ingår i: New England Journal of Medicine. - 0028-4793. ; 350:26, s. 2663-2672
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: We studied the effect on skin papillomas of topical application of a complex of α-lactalbumin and oleic acid (often referred to as human α-lactalbumin made lethal to tumor cells [HAMLET]) to establish proof of the principle that α-lactalbumin-oleic acid kills transformed cells but not healthy, differentiated cells. METHODS: Forty patients with cutaneous papillomas that were resistant to conventional treatment were enrolled in a randomized, placebo-controlled, double-blind study, in which α-lactalbumin-oleic acid or saline placebo was applied daily for three weeks and the change in the volume of each lesion was recorded. After this first phase of the study, 34 patients participated in the second phase, an open-label trial of a three-week course of α-lactalbumin-oleic acid. Approximately two years after the end of the open-label phase of the study, 38 of the original 40 patients were examined, and long-term follow-up data were obtained. RESULTS: In the first phase of the study, the lesion volume was reduced by 75 percent or more in all 20 patients in the α-lactalbumin-oleic acid group, and in 88 of 92 papillomas; in the placebo group, a similar effect was evident in only 3 of 20 patients (15 of 74 papillomas) (P<0.001). After the patients in the initial placebo group had been treated with α-lactalbumin-oleic acid in the second phase of the study, a median reduction of 82 percent in lesion volume was observed. At follow-up two years after the end of the second phase, all lesions had completely resolved in 83 percent of the patients treated with α-lactalbumin-oleic acid, and the time to resolution was shorter in the group originally assigned to receive a-lactalbumin-oleic acid than among patients originally in the placebo group (2.4 vs. 9.9 months; P<0.01). No adverse reactions were reported, and there was no difference in the outcomes of treatment between immunocompetent and immunosuppressed patients. CONCLUSIONS: Treatment with topical α-lactalbumin-oleic acid has a beneficial and lasting effect on skin papillomas.
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| 8. |
- Hallgren, Oskar, et al.
(författare)
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Apoptosis and tumor cell death in response to HAMLET (human alpha-lactalbumin made lethal to tumor cells).
- 2008
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Ingår i: Advances in Experimental Medicine and Biology. - New York, NY : Springer New York. - 0065-2598. ; 606, s. 217-240
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Forskningsöversikt (refereegranskat)abstract
- HAMLET (human alpha-lactalbumin made lethal to tumor cells) is a molecular complex derived from human milk that kills tumor cells by a process resembling programmed cell death. The complex consists of partially unfolded alpha-lactalbumin and oleic acid, and both the protein and the fatty acid are required for cell death. HAMLET has broad antitumor activity in vitro, and its therapeutic effect has been confirmed in vivo in a human glioblastoma rat xenograft model, in patients with skin papillomas and in patients with bladder cancer. The mechanisms of tumor cell death remain unclear, however. Immediately after the encounter with tumor cells, HAMLET invades the cells and causes mitochondrial membrane depolarization, cytochrome c release, phosphatidyl serine exposure, and a low caspase response. A fraction of the cells undergoes morphological changes characteristic of apoptosis, but caspase inhibition does not rescue the cells and Bcl-2 overexpression or altered p53 status does not influence the sensitivity of tumor cells to HAMLET. HAMLET also creates a state of unfolded protein overload and activates 20S proteasomes, which contributes to cell death. In parallel, HAMLET translocates to tumor cell nuclei, where high-affinity interactions with histones cause chromatin disruption, loss of transcription, and nuclear condensation. The dying cells also show morphological changes compatible with macroautophagy, and recent studies indicate that macroautophagy is involved in the cell death response to HAMLET. The results suggest that HAMLET, like a hydra with many heads, may interact with several crucial cellular organelles, thereby activating several forms of cell death, in parallel. This complexity might underlie the rapid death response of tumor cells and the broad antitumor activity of HAMLET.
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| 9. |
- Mossberg, Anki, et al.
(författare)
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Bladder cancers respond to intravesical instillation of HAMLET (human alpha-lactalbumin made lethal to tumor cells).
- 2007
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Ingår i: International Journal of Cancer. - : Wiley. - 0020-7136 .- 1097-0215. ; 121:6, s. 1352-1359
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Tidskriftsartikel (refereegranskat)abstract
- We studied if bladder cancers respond to HAMLET (human alpha-lactalburnin made lethal to tumor cells) to establish if intravesical HAMLET application might be used to selectively remove cancer cells in vivo. Patients with nonmuscle invasive transitional cell carcinomas were included. Nine patients received 5 daily intravesical instillations of HAMLET (25 mg/ml) during the week before scheduled surgery. HAMLET stimulated a rapid increase in the shedding of tumor cells into the urine, daily, during the 5 days of instillation. The effect was specific for HAMLET, as intravesical instillation of NaCl, PBS or native a-lactalbumin did not increase cell shedding. Most of the shed cells were dead and an apoptotic response was detected in 6 of 9 patients, using the TUNEL assay. At surgery, morphological changes in the exophytic tumors were documented by endoscopic photography and a reduction in tumor size or change in tumor character was detected in 8 of 9 patients. TUNEL staining was positive in biopsies from the remaining tumor in 4 patients but adjacent healthy tissue showed no evidence of apoptosis and no toxic response. The results suggest that HAMLET exerts a direct and selective effect on bladder cancer tissue in vivo and that local HAMLET administration might be of value in the future treatment of bladder cancers. (c) 2007 Wiley-Liss, Inc.
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| 10. |
- Pettersson, Jenny, et al.
(författare)
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Can misfolded proteins be beneficial? The HAMLET case.
- 2009
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Ingår i: Annals of Medicine. - : Informa UK Limited. - 1365-2060 .- 0785-3890. ; 41, s. 162-176
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Forskningsöversikt (refereegranskat)abstract
- By changing the three-dimensional structure, a protein can attain new functions, distinct from those of the native protein. Amyloid-forming proteins are one example, in which conformational change may lead to fibril formation and, in many cases, neurodegenerative disease. We have proposed that partial unfolding provides a mechanism to generate new and useful functional variants from a given polypeptide chain. Here we present HAMLET (Human Alpha-lactalbumin Made LEthal to Tumor cells) as an example where partial unfolding and the incorporation of cofactor create a complex with new, beneficial properties. Native alpha-lactalbumin functions as a substrate specifier in lactose synthesis, but when partially unfolded the protein binds oleic acid and forms the tumoricidal HAMLET complex. When the properties of HAMLET were first described they were surprising, as protein folding intermediates and especially amyloid-forming protein intermediates had been regarded as toxic conformations, but since then structural studies have supported functional diversity arising from a change in fold. The properties of HAMLET suggest a mechanism of structure-function variation, which might help the limited number of human protein genes to generate sufficient structural diversity to meet the diverse functional demands of complex organisms.
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