calpain and Carcinoma--Lewis-Lung

Janus kinase/signal transducer and activator of transcription (JAK/STAT) signals and their endogenous inhibitor, suppressor of cytokine signaling 3 (SOCS3), in vascular endothelial cells (ECs) reportedly dominate the pathological angiogenesis. However, how these inflammatory signals are potentiated during pathological angiogenesis has not been fully elucidated. We suspected that an intracellular protease calpain, which composes the multifunctional proteolytic systems together with its endogenous inhibitor calpastatin (CAST), contributes to the JAK/STAT regulations.. To specify the effect of EC calpain/CAST systems on JAK/STAT signals and their relationship with pathological angiogenesis.. The loss of CAST, which is ensured by several growth factor classes, was detectable in neovessels in murine allograft tumors, some human malignant tissues, and oxygen-induced retinopathy lesions in mice. EC-specific transgenic introduction of CAST caused downregulation of JAK/STAT signals, upregulation of SOCS3 expression, and depletion of vascular endothelial growth factor (VEGF)-C, thereby counteracting unstable pathological neovessels and disease progression in tumors and oxygen-induced retinopathy lesions in mice. Neutralizing antibody against VEGF-C ameliorated pathological angiogenesis in oxygen-induced retinopathy lesions. Small interfering RNA-based silencing of endogenous CAST in cultured ECs facilitated μ-calpain-induced proteolytic degradation of SOCS3, leading to VEGF-C production through amplified interleukin-6-driven STAT3 signals. Interleukin-6-induced angiogenic tube formation in cultured ECs was accelerated by CAST silencing, which is suppressible by pharmacological inhibition of JAK/STAT signals, antibody-based blockage of VEGF-C, and transfection of calpain-resistant SOCS3, whereas transfection of wild-type SOCS3 exhibited modest angiostatic effects.. Loss of CAST in angiogenic ECs facilitates μ-calpain-induced SOCS3 degradation, which amplifies pathological angiogenesis through interleukin-6/STAT3/VEGF-C axis.

Topics: Adenocarcinoma; Amino Acid Sequence; Animals; Aorta; Calcium-Binding Proteins; Calpain; Carcinoma, Lewis Lung; Cells, Cultured; Cytokines; Endothelial Cells; Female; Glioblastoma; Humans; Janus Kinases; Male; Mice; Mice, Inbred C57BL; Mice, Transgenic; Molecular Sequence Data; Mutagenesis, Site-Directed; Neoplasms; Neovascularization, Pathologic; Recombinant Fusion Proteins; Retinopathy of Prematurity; Signal Transduction; STAT Transcription Factors; Suppressor of Cytokine Signaling 3 Protein; Suppressor of Cytokine Signaling Proteins; Vascular Endothelial Growth Factor C

Overexpression of the proto-oncogene c-ski in mice results in the development of a hypertrophic phenotype, characterized by increases in body and muscle weights. It has been previously shown in our laboratories that down-regulation of muscle protein breakdown associated with reduced expression of genes pertaining to different proteolytic systems likely account for this hypertrophic pattern. The aim of the present study was to evaluate the resistance of c-ski transgenic mice to catabolic stimuli such as those induced by the growth of the Lewis lung carcinoma. The tumor elicited a loss of body weight either in transgenic or in non-transgenic animals, although it was less pronounced in the former. The mass of gastrocnemius, tibialis and extensor digitorum longus (EDL) muscles were significantly reduced in non-transgenic tumor-bearing mice. Despite the anabolic setting displayed by the transgenic animals, the EDL only is completely protected against wasting. Indeed, gastrocnemius, tibialis and soleus show a reduction in weight, the latter two being significantly more depleted when compared to the non-transgenic tumor bearers. Similarly, the perigenital white adipose tissue presented a reduced mass which was more marked in the transgenic group. The quantitation of gene expression for ubiquitin, E2, C8 and calpain in the EDL showed marked differences between the transgenic and the non-transgenic groups of tumor hosts. As expected from previous results, in the latter group most of the transcripts examined increased with respect to controls as a consequence of tumor growth; by contrast, in the transgenic tumor hosts there was a significant reduction of ubiquitin, E2, C8 subunit, and calpain mRNA levels in comparison with the transgenic tumor-free animals. These results show that c-ski hyperexpression prevents tumor-induced muscle wasting in the EDL muscle, likely by impairing the state of activation of different proteolytic systems. However, the lack of effectiveness in the other muscles examined suggests that the achievement of a significant interference with the development of cachexia at the molecular level is not an easy task and probably should be designed taking into consideration more than one target.

Topics: Animals; Body Weight; Cachexia; Calpain; Carcinoma, Lewis Lung; DNA-Binding Proteins; Female; Gene Expression Regulation, Neoplastic; Male; Mice; Mice, Transgenic; Neoplasm Transplantation; Organ Size; Proteasome Endopeptidase Complex; Proto-Oncogene Proteins; RNA, Messenger; Ubiquitin