cobra-cardiotoxin-proteins and Carcinoma--Squamous-Cell

Cardiotoxin III (CTX III), a basic polypeptide with 60-amino acid residues isolated from Naja naja atra venom, has been reported to have cytotoxic activity. CTX III exerted cytotoxicity with the S-phase cell cycle arrest, correlated with a marked decrease in the expression levels of cyclin A, cyclin B, and cyclin-dependent kinase 1 (CDK1), and apoptosis, accompanied with Bax and Bad up-regulation, and the down-regulation of Bcl-2, p-Bad, and X-linked inhibitor of apoptosis (XIAP) with cytochrome c release and sequential activation of caspase-9 and caspase-3 in Ca9-22 cells. Mechanistic studies showed that CTX III suppressed the phosphorylation of Src, EGFR, STAT3, STAT5, Akt, and activation of PI3 K (p110). Moreover, Src inactivation was observed earlier than that of the EGFR and the Src inhibitor PP2 suppressed the levels of phospho-EGFR, phospho-STAT3, phospho-STAT5, phospho-Akt, and PI3 K(p110). The PP2 also caused the S-phase arrest and apoptosis, and led to down-regulation of Bcl-2, p-Bad, XIAP, cyclin A, cyclin B, and CDK1, and up-regulation of Bax and Bad, similar to that observed in CTX III treatment. Taken together, these results indicate that CTX III induces apoptosis and S-phase arrest in Ca9-22 cells via concomitant inactivation of the Src, EGFR, STAT3, STAT5, PI3 K(p110), and Akt signaling pathways.

Topics: Animals; Apoptosis; bcl-Associated Death Protein; Carcinoma, Squamous Cell; Cell Cycle; Cell Line, Tumor; Cobra Cardiotoxin Proteins; Elapid Venoms; Elapidae; Enzyme Activation; ErbB Receptors; Humans; Mouth Neoplasms; Phosphorylation; Proto-Oncogene Proteins c-akt; Proto-Oncogene Proteins c-bcl-2; Proto-Oncogene Proteins pp60(c-src); STAT3 Transcription Factor; STAT5 Transcription Factor; Transcriptional Activation; X-Linked Inhibitor of Apoptosis Protein

Cardiotoxin III (1), a basic polypeptide with 60 amino acid residues isolated from Naja naja atra venom, has potential therapeutic activity in cancer. Treatment with 1 reduced phosphorylation of EGFR and Akt, as well as ERK in Ca9-22 cells. Moreover, 1-treatment inhibited constitutive activation of STAT3 and STAT5 in a time-dependent manner. Up-regulation of Bax and down-regulation of anti-apoptotic proteins including Bcl-2, Bcl-X(L), and myeloid cell leukemia-1(Mcl-1) were also found in cells treated with 1. In addition, 1-treatment disrupted mitochondrial membrane potential (DeltaPsim) and resulted in release of mitochondrial cytochrome c and activation of both caspases-9 and -3. AG1478, a specific pharmacological inhibitor of EGFR activation, mimics the cytotoxic effects of 1. Taken together, these results showed that 1 causes significant induction of apoptosis in Ca9-22 cells via abolition of the EGFR-mediated survival pathway of these cells. Thus, cardiotoxin III appears to be a potential therapeutic agent for killing oral squamous carcinoma Ca9-22 cells.

Topics: Antineoplastic Agents; Carcinoma, Squamous Cell; Cobra Cardiotoxin Proteins; Elapid Venoms; ErbB Receptors; Humans; Membrane Potential, Mitochondrial; Phosphorylation; Protein Conformation; Proto-Oncogene Proteins c-akt; Quinazolines; Tyrphostins

The authors report their clinical experience with VRCTC-310 in two patients suffering with advanced cancer in which the skin was severely compromised. VRCTC-310 is a combination of the snake venoms crotoxin (CT) and cardiotoxin (CD). The local (peritumoral) treatment with the drug (0.O14 mg/kg/week during 6 weeks) provoked the complete disappearance of a relapsed skin squamous cell cancer in one patient. The other patient was an aged woman with local-advanced breast cancer (carcinoma en cuirasse) who was inoculated intra-and-peritumoral with VRCTC-310. After 6 weekly courses (0.014 mg/kg/week) with the drug a > 80% tumor reduction was seen. A 133 days follow-up demonstrated not only an objective complete response of the primary tumor mass, but the disappearance of supraclavicular tumor mass as well a significant reduction in lymphangitis. To our knowledge, this is the first communication about the in vivo antitumoral activity of VRCTC-310 when injected locally to humans. Further studies are now in progress.

Topics: Aged; Antineoplastic Agents; Breast Neoplasms; Carcinoma, Squamous Cell; Cobra Cardiotoxin Proteins; Crotoxin; Drug Combinations; Female; Humans; Male; Skin Neoplasms