The microtubule-targeting antineoplastic agent, paclitaxel, is highly efficacious against a wide spectrum of human cancers. However, dose-limiting toxicity and development of drug resistance limit its clinical application. Development of novel strategies that overcome chemoresistance and sensitize cancer cells to paclitaxel can enhance the therapeutic effect of this drug. We have previously shown that curcumin, a natural polyphenol, enhances paclitaxelinduced cytotoxicity in vitro through downregulation of nuclear factor (NF)-jB and Akt pathways. This study was undertaken to determine whether this synergism exists in vivo and to elucidate the underlying molecular mechanisms. Mouse cervical multistage squamous cell carcinoma model using 3-methylcholanthrene (3-MC) and a xenograft model of human cervical cancer in nonobese diabetic severe combined immunodeficient (NOD-SCID) mice using HeLa cells were used to evaluate the synergism. We observed that the combined treatment of curcumin and paclitaxel induced a synergestic reduction in the tumor incidence as well as tumor volume of animals compared with the individual treatments of paclitaxel or curcumin, although curcumin alone could not induce any significant effect at the concentration used. The results suggest that a suboptimal concentration of curcumin augments the antitumor action of paclitaxel by downregulating the activation and downstream signaling of antiapoptotic factors and survival signals such as NF-jB, Akt and mitogen-activated protein kinases that have significant roles in proliferation, survival, angiogenesis and metastasis. This study revealed for the first time that 3-MC-induced tumorigenesis in mice is associated with a strong constitutive activation of NF-jB activity. Furthermore, we also observed that pre-exposure of carcinoma cells isolated from 3-MC-induced tumors to curcumin potentiates paclitaxel-induced apoptosis. Overall, the findings of this preclinical study provide a strong rationale for the validation of this combination through clinical trials. As curcumin could effectively downregulate all these survival signals induced by paclitaxel, we suggest it as a potent chemosensitizer to improve the therapeutic index of paclitaxel.
Human Papilloma Virus (HPV) is one of the most common sexually transmitted pathogen, globally. Oncogenic types of HPV are the causative agents of many neoplastic diseases, including cervical cancer, which ranks as the most common cancer affecting females in developing countries. HPV infection of the cervical epithelium and the subsequent integration of viral DNA into the host genome are the major risk factors for cervical cancer. The scientific discovery of HPV as the causal agent of cervical cancer has led to the development of HPV-based diagnostic tools. Prophylactic vaccines, based on the oncogenic HPV type virus-like particles have been introduced in several developed countries as a preliminary preventive approach. Nevertheless, it remains a continuous threat to women in developing countries, where the prophylactic vaccines are unaffordable and organized screening programmes are lacking. This warrants implementation of prevention strategies that will reduce cervical cancer-related mortality. In this review, we have discussed molecular pathogenesis of HPV infection and the risk factors associated with it. The diagnosis, treatment and prevention strategies of HPV-related cervical cancer have also been discussed.
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