TriCurin in human papillomavirus-positive (HPV) head and neck squamous cell carcinoma
Head and neck tumors comprise a group of different cancers that occur in the head and neck region. More than 90% of malignancies of this type are carcinomas of the larynx, pharynx, lip, and oral cavity. These arise in the squamous epithelium, which is why they are also called squamous cell carcinomas. Adenocarcinomas, such as carcinomas of the nose and sinuses, sarcomas, and lymphomas, on the other hand, occur less frequently. Approximately 600,000 new cases of head and neck tumors occur annually worldwide. Risk factors include tobacco, alcohol, harmful substances that enter the body through the respiratory system such as asbestos and wood dust, but also UV and radioactive rays, a weakened immune system, poor oral hygiene, and chronic irritable conditions. Certain viral infections, such as the Eppstein-Barr virus and especially the human papillomaviruses (HPV) are also considered risk factors. Conventional medical treatments for these tumors rely on surgery, radiation and chemotherapy. A study published in 2016 made significant findings in the effect of a preparation consisting of the polyphenols curcumin from the spice turmeric, resveratrol from red grapes and epigallocatechin gallate (EGCG) from green tea on HPV-positive head and neck squamous cell carcinoma cell lines and in mice with HPV-positive head and neck squamous cell carcinomas.
The compound known as TriCurin, whose components are in the synergistic ratio of 4:1:12.5 (curcumin:EGCG:resveratrol), was first applied to the two high-risk HPV16-positive head and neck squamous cell carcinoma cell lines UMSCC47 and UPCI:SCC090. It was observed that the induced apoptosis of the cell lines was approximately 68% (UMSCC47) and approximately 17% (UPCI:SCC090), while it was only approximately 3% (UMSCC47) and 5% (UPCI:SCC090) in the control group.
In addition, clonogenic survival assays were performed to investigate the clonal proliferation of surviving cells. The number of surviving clones of UMSCC47 cells was approximately 130 in the control group, whereas application of TriCurin resulted in approximately 40 surviving clones, causing a reduction of approximately 69%. In the UPCI:SCC090 cells, the number of surviving clones was approximately 250 and reduced by approximately 90% after application of TriCurin with approximately 25 clones (UPCI:SCC090).
In addition, we examined the effect on UMSCC47 cells with the combination of TriCurin and irradiation and compared it to treatment consisting of irradiation alone. Clonogenic cell survival decreased by 45% with irradiation, whereas treatment with the combination of TriCurin and irradiation resulted in a reduction of surviving clones by approximately 80%.
In another assay, the effect of TriCurin at different doses on the efficiency to form tumor spheres of both cell lines was investigated and compared with a control group in each case. Administration of TriCurin decreased the efficiency of tumor sphere formation with increasing dosage.
At the highest concentration of approximately 10 μM, TriCurin reduced the tumor sphere formation efficiency compared with the control group by approximately 58%-74% of UMSCC47 cells and by approximately 52%-61% of UPCI:SCC090 cells. In addition, compared with the control group, tumor sphere reduced by approximately 16% (UMSCC47) and by approximately 19% (UPCI:SCC090).
Furthermore, we investigated whether TriCurin had an effect on the HPV16 oncogenes E6 and E7. HPV16 oncogenes E6 and E7 deactivate p53 protein and retinoblastoma protein, resulting in promotion of carcinogenesis. TriCurin treatment reduced mRNA expression of HPV16 oncogenes E6 and E7 and protein levels of UMSCC47 and UPCI:SCC090 cells. In addition, an increase in p53 and retinoblastoma levels was observed after TriCurin treatment. In a final study, the effect of TriCurin was analyzed in mice with HPV16-positive head and neck squamous cell carcinoma (UMSCC47 cells). The mice were divided into a group that was administered TriCurin three times a week for five weeks and a control group.
At the end of the five weeks, it was found that the mean tumor weight in the control group was approximately 904 mg, while in the TriCurin-treated group it was approximately 124 mg, representing a reduction in tumor weight of approximately 86%. It also showed that the majority of the tumors in the TriCurin-treated mice consisted of large necrotic areas, with small areas of tumor cells present in the tumor periphery.
In contrast, the tumors from the control group consisted mostly of tumor cells. The tumors from the control group also had necrotic tissue, but comparatively much less than the TriCurin-treated tumors. In addition, TriCurin treatment was shown to reduce the number of actively proliferating tumor cells by nearly 20% compared with the control group. In addition, TriCurin reduced intratumoral levels of HPV16 E6 by approximately 94%.
The results of the studies give reason to explore TriCurin with regard to HPV-positive head and neck squamous cell carcinoma as an alternative or adjunct to conventional medical treatments in humans.