[Corrigendum] Novel polygodial analogs P3 and P27: Efficacious therapeutic agents disrupting mitochondrial function in oral squamous cell carcinoma.

After the publication of the above article, the authors have realized that they failed to properly acknowledge the work performed by their Center for Innovative Drug Discovery High Throughput Screening Core Facility in the paper. The Declarations section of their paper should therefore have also included the following statement: "The UT Health San Antonio Center for Innovative Drug Discovery HTS Facility was funded in part by the Cancer Prevention Research Institute of Texas (CPRIT; grant no. RP160844)". The authors regret their oversight in failing to include this information in the Declarations section of their paper. [the original article was published in International Journal of Oncology 53: 2627-2636, 2018; DOI: 10.3892/ijo.2018.4585].

The novel capsazepine analog, CIDD-99, significantly inhibits oral squamous cell carcinoma in vivo through a TRPV1-independent induction of ER stress, mitochondrial dysfunction, and apoptosis.

BACKGROUND: Oral squamous cell carcinoma (OSCC) is a deadly disease with a mere 40% five-year survival rate for patients with advanced disease. Previously, we discovered that capsazepine (CPZ), a transient receptor potential channel, Vanilloid subtype 1 (TRPV1) antagonist, has significant anti-tumor effects against OSCC via a unique mechanism-of-action that is independent of TRPV1. Thus, we developed novel CPZ analogs with more potent anti-proliferative effects (CIDD-24, CIDD-99, and CIDD-111). METHODS: Using OSCC xenograft models, we determined the efficacy of these analogs in vivo. TRPV1 interactions were evaluated using calcium imaging and a rat model of orofacial pain. Anti-cancer mechanism(s)-of-action were assessed by cell cycle analysis and mitochondrial depolarization assays. RESULTS: CIDD-99 was the most potent analog demonstrating significant anti-tumor effects in vivo (P < 0.001). CIDD-24 was equipotent to the parent compound CPZ, but less potent than CIDD-99. CIDD-111 was the least efficacious analog. Calcium imaging studies confirmed that CIDD-99 neither activates nor inhibits TRPV1 confirming that TRPV1 activity is not involved in its anti-cancer effects. All analogs induced an S-phase block, dose-dependent mitochondrial depolarization, and apoptosis. Histological analyses revealed increased apoptosis and reduced cell proliferation in tumors treated with these analogs. Importantly, CIDD-99 had the most dramatic anti-tumor effects with 85% of tumors resolving leaving only minute traces of viable tissue. Additionally, CIDD-99 was non-noxious and demonstrated no observable adverse reactions CONCLUSION: This study describes a novel, highly efficacious, CPZ analog, CIDD-99, with dramatic anti-tumor effects against OSCC that may be efficacious as a lone therapy or in combination with standard therapies.

Novel polygodial analogs P3 and P27: Efficacious therapeutic agents disrupting mitochondrial function in oral squamous cell carcinoma.

Polygodial, a drimane sesquiterpenoid dialdehyde isolated as a pungent component of the water pepper Persicaria hydropiper, exhibits antifeedant, antimicrobial, anti-inflammatory and anticancer effects. Polygodial also activates transient receptor potential vanilloid subtype 1 (TRPV1) channels. Previously, we described the synthesis of a C12-Wittig derivative of polygodial, termed P3, with significant antiproliferative effects against multiple cancer types including oral squamous cell carcinoma (OSCC). In the present study, a more potent derivative, P27, with superior anti-proliferative effects in vitro and antitumor effects in Cal-27 derived xenografts is described. Polygodial, P3, and P27 all significantly decreased OSCC tumor growth, with P27 being equipotent with polygodial and P3 being the least efficacious. However, neither analog elicited the adverse effect observed with polygodial: Profound transient inflammation. Although P3 and P27 pharmacophores are based on polygodial, novel effects on OSCC cell cycle distribution were identified and shared anticancer effects that are independent of TRPV1 activity were observed. Polygodial elicits an S-phase block, whereas P3 and P27 lead to G2/M phase arrest. Pretreatment of OSCC cells with the TRPV1 antagonist capsazepine does not affect the antiproliferative activity of P3 or P27, indicating that TRPV1 interactions do not regulate OSCC cell proliferation. Indeed, calcium imaging studies identified that the analogs neither activate nor antagonize TRPV1. Behavioral studies using a rat model for orofacial pain confirmed that these analogs fail to induce nocifensive responses, indicating that they are non-noxious in vivo. All compounds induced a significant concentration-dependent decrease in the mitochondrial transmembrane potential and corresponding apoptosis. Considering that P27 is equipotent to polygodial with no TRPV1-associated adverse effects, P27 may serve as an efficacious novel therapy for OSCC.