Sensitivity of Cutaneous T-Cell Lymphoma Cells to the Mcl-1 Inhibitor S63845 Correlates with the Lack of Bcl-w Expression.

Long-term, curative treatment of cutaneous T-cell lymphomas (CTCL) remains a major challenge. Therapy resistance is often based on apoptosis deficiency, and may depend on antiapoptotic Bcl-2 proteins, such as Bcl-2, Bcl-xL, Bcl-w and Mcl-1. For their targeting, several antagonists have been generated, which mimic the Bcl-2 homology domain 3 (BH3 mimetics). As dysregulation and overexpression of Mcl-1 has been reported in CTCL, the use of Mcl-1 inhibitors appears as an attractive strategy. Here, we investigated the effects of the selective Mcl-1 inhibitor S63845 in a series of four CTCL cell lines, in comparison to ABT-263 and ABT-737 (inhibitors of Bcl-2, Bcl-xL and Bcl-w). In two cell lines (HH, HuT-78), S63845 resulted in significant apoptosis induction, decrease in cell viability, loss of mitochondrial membrane potential and caspase activation, while two other cell lines (MyLa, SeAx) remained completely resistant. An inverse correlation was found, as S63845-resistant cells were highly sensitive to ABT-263/-737, and S63845-sensitive cells showed only moderate sensitivity to ABTs. Combinations of S63845 and ABT-263 partially yielded synergistic effects. As concerning Bcl-2 protein expression, weaker Mcl-1 expression was found in S63845-resistant MyLa and SeAx, while for Bcl-2 and Bcl-xL, the lowest expression was found in the highly sensitive cell line HH. The most striking difference between S63845-resistant and -sensitive cells was identified for Bcl-w, which was exclusively expressed in S63845-resistant cells. Thus, CTCL may be efficiently targeted by BH3 mimetics, providing the right target is preselected, and Bcl-w expression may serve as a suitable marker.

Targeting Cutaneous T-Cell Lymphoma Cells by Ingenol Mebutate (PEP005) Correlates with PKCδ Activation, ROS Induction as Well as Downregulation of XIAP and c-FLIP.

New therapeutic strategies are needed for cutaneous T-cell lymphoma (CTCL), and the plant extract ingenol mebutate (PEP005) may be considered. PEP005 has been approved for actinic keratosis, and proapoptotic activities were described in different cancer cells. Here, we aimed to investigate its efficacy in four CTCL cell lines and its mode of action. While HuT-78 and HH responded with induced apoptosis as well as with loss of cell viability and cell proliferation, MyLa and SeAx remained resistant. Interestingly, both sensitive and resistant cells showed caspase-8 activation and enhanced levels of reactive oxygen species (ROS), while final caspase-3 activation was restricted to sensitive cells. Apoptosis induction was prevented by the caspase inhibitor QVD-Oph as well as by the antioxidant vitamin E. Caspase activation by PEP005 may be explained to some extent by the downregulation of the caspase antagonistic proteins c-FLIP and XIAP in sensitive cells, whereas both proteins were strongly expressed in resistant cells. Finally, PEP005 resulted in the activation of proapoptotic PKCδ, and the PKC inhibitor bisindolylmaleimide I reduced apoptosis, caspase-3 processing and ROS production, as well as restored cell viability. In conclusion, PKCδ appeared as a central player in apoptosis regulation in CTCL cells, also suggesting its therapeutic targeting.

Key Role of Reactive Oxygen Species (ROS) in Indirubin Derivative-Induced Cell Death in Cutaneous T-Cell Lymphoma Cells.

Cutaneous T-cell lymphoma (CTCL) may develop a highly malignant phenotype in its late phase, and patients may profit from innovative therapies. The plant extract indirubin and its chemical derivatives represent new and promising antitumor strategies. This first report on the effects of an indirubin derivative in CTCL cells shows a strong decrease of cell proliferation and cell viability as well as an induction of apoptosis, suggesting indirubin derivatives for therapy of CTCL. As concerning the mode of activity, the indirubin derivative DKP-071 activated the extrinsic apoptosis cascade via caspase-8 and caspase-3 through downregulation of the caspase antagonistic proteins c-FLIP and XIAP. Importantly, a strong increase of reactive oxygen species (ROS) was observed as an immediate early effect in response to DKP-071 treatment. The use of antioxidative pre-treatment proved the decisive role of ROS, which turned out upstream of all other proapoptotic effects monitored. Thus, reactive oxygen species appear as a highly active proapoptotic pathway in CTCL, which may be promising for therapeutic intervention. This pathway can be efficiently activated by an indirubin derivative.

Can we improve the efficacy of modern cataract surgery by using different tip designs? A comparison of balanced and tapered tip in femtosecond laser-assisted cataract surgery and manual phacoemulsification.

IMPORTANCE: Different tip designs in modern cataract surgery have not been studied between the reported systems. BACKGROUND: Aim of this study is to assess the efficacy of two tip designs, Intrepid® balanced tip (BT) and Kelman tapered tip (TT), in femtosecond laser assisted cataract surgery (FLACS) and the microcoaxial torsional phacoemulsification. DESIGN: Prospective randomized unmasked cohort outcome study (hospital setting). PARTICIPANTS: Threehundert-forty-three eyes of 343 patientes underwent cataract surgery. METHODS: Data of n = 196 FLACS and n = 147 manual phacoemulsification were analysed. Intrepid® balanced tip and Kelman tapered tip, Alcon, USA, were tested in FLACS (LenSx Alcon, USA) und manual phaco (Alcon Centurion System, USA). Four study cohorts were formed; FLACS BT (n = 90, 70.2 years), FLACS TT (n = 106, 68.1years), Manual BT (n = 70, 71.3 years), Manual TT (n = 77, 71.8 years). The nuclei were graded in Lens Opacities Classification System (LOCS) II,III and IV. MAIN OUTCOME MEASURES: Cumulative dissipated energy (CDE%s), balanced salt solution volume (BSSml), total longitudinal energy (%s) and torsional amplitude (%s). RESULTS: Lower CDE values were seen in FLACS compared to manual phacoemulsification (CDE %s median FLACS BT 3.28, FLACS TT 4.07, Manual BT 5.57, Manual TT 6.27). There was a significant difference between CDE FLACS BT and FLACS TT (p = 0.038), and between FLACS BT and Manual TT (p = 0.001). CONCLUSIONS AND RELEVANCE: The right choice of tip designs in advanced phacoemulsification systems is a key factor in increasing efficacy in cataract surgery. The balanced tip showed a considerable energy-saving advantage in FLACS and manual phacoemulsification compared to the tapered tip.