A cancer cell-specific inducer of apoptosis

Attenuation of autophagy flux by 6-shogaol sensitizes human liver cancer cells to TRAIL-induced apoptosis via p53 and ROS

Tumor necrosis factor (TNF)‑related apoptosis‑inducing ligand (TRAIL) is a member of the TNF superfamily and is an antitumor drug that induces apoptosis in tumor cells with minimal or no effects on normal cells. Here, it is demonstrated that 6‑shogaol (6‑sho), a bioactive component of ginger, exerted anti‑inflammatory and anticancer properties, attenuated tumor cell propagation and induced TRAIL‑mediated cell death in liver cancer cells. The current study identified a potential pathway by revealing that TRAIL and 6‑sho or chloroquine acted together to trigger reactive oxygen species (ROS) production, to upregulate tumor‑suppressor protein 53 (p53) expression and to change the mitochondrial transmembrane potential (MTP). Treatment with N‑acetyl‑L‑cysteine reversed these effects, restoring the MTP and attenuated ROS production and p53 expression. Interestingly, treatment with 6‑sho increased p62 and microtubule‑associated proteins 1A/1B light chain 3B‑II levels, indicating an inhibited autophagy flux. In conclusion, attenuation of 6‑sho‑induced autophagy flux sensitized cells to TRAIL‑induced apoptosis via p53 and ROS, suggesting that the administration of TRAIL in combination with 6‑sho may be a suitable therapeutic method for the treatment of TRAIL‑resistant Huh7 liver cells.

A Novel Small Peptide Inhibitor of NFκB, RH10, Blocks Oxidative Stress-Dependent Phenotypes in Cancer

Background

The RH domain of GRK5 is an effective modulator of cancer growth through the inhibition of NFκB activity. The aim of this study was to identify the minimum effective sequence of RH that is still able to inhibit tumor growth and could be used as a peptide-based drug for therapy.

Methods

Starting from the RH sequence, small peptides were cloned and tested in KAT-4 cells. The effects on NFκB signaling and its dependent phenotypes were evaluated by Western blot, TUNEL assay, proliferation assay, and angiogenesis in vitro. In vivo experiments were performed in KAT-4 xenografts in Balb/c nude mice.

Results

A minimum RH ten amino acids long sequence (RH10) was able to interact with IκB, to increase IκB levels, to induce apoptosis, to inhibit KAT4-cell proliferation, NFκB activation, ROS production, and angiogenesis in vitro. In vivo, the peptide inhibited tumor growth in a dose-dependent manner. We also tested its effects in combination with chemotherapeutic drugs and radiotherapy. RH10 ameliorated the antitumor responses to cisplatin, doxorubicin, and ionizing radiation.

Conclusion

Our data propose RH10 as a potential peptide-based drug to use for cancer treatment both alone or in combination with anticancer therapies.

Suppressive Effect of Constructed shRNAs against Apollon Induces Apoptosis and Growth Inhibition in the HeLa Cell Line

Background:

Cervical cancer is the second most common female cancer worldwide. Inhibitors of apoptosis proteins (IAPs) block apoptosis; therefore, therapeutic strategies targeting IAPs have attracted the interest of researchers in recent years. Apollon, a member of IAPs, inhibits apoptosis and cell death. RNA interference is a pathway in which small interfering RNA (siRNA) or shRNA (short hairpin RNA) inactivates the expression of target genes. The purpose of this study was to determine the effect of constructed shRNAs on apoptosis and growth inhibition through the suppression of apollon mRNA in HeLa cell line.

Methods:

Three shRNAs with binding ability to three different target sites of the first region of apollon gene were designed and cloned in pRNAin-H1.2/Neo vector. shRNA plasmids were then transfected in HeLa cells using electroporation. Down-regulation effects of apollon and the viability of HeLa cells were analyzed by RT-PCR, lactate dehydrogenase assay, and MTT assay, respectively. Also, the induction and morphological markers of apoptosis were evaluated by caspase assay and immunocytochemistry method.

Results:

The expression of shRNA in HeLa cells caused a significant decrease in the level of apollon mRNA1. In addition, shRNA1 effectively increased the mRNA level of Smac (as the antagonist of apollon), reduced the viability of HeLa cells and exhibited immunocytochemical apoptotic markers in this cell line.

Conclusion:

Apollon gene silencing can induce apoptosis and growth impairment in HeLa cells. In this regard, apollon can be considered a candidate therapeutic target in HeLa cells as a positive human papillomavirus cancer cell line.

Papillomavirus-associated squamous skin cancers following transplant immunosuppression: one Notch closer to control

The frequent occurrence of cutaneous squamous cell carcinomas (SCCs) containing weakly tumorigenic human papillomaviruses (HPVs) following iatrogenic immunosuppression for organ transplantation remains incompletely understood. Here we address this problem in the light of recent insights into (1) the association of low-risk β-HPVs with skin SCCs in the rare genetic syndromes of epidermodysplasia verruciformis and xeroderma pigmentosum, (2) the frequent recovery of post-transplant tumor control on substituting calcineurin-inhibitory with mTOR-inhibitory immunosuppression, (3) the unexpectedly favorable prognosis of node-positive SCCs containing high-risk α-HPVs originating in the activated immune niche of the oropharynx, (4) the rapid occurrence of HPV-negative SCCs in ultraviolet (UV)-damaged skin of melanoma patients receiving Raf-inhibitory drugs, and (5) the selective ability of β-HPV E6 oncoproteins to inhibit Notch tumor-suppressive signaling in cutaneous and mesenchymal tissues. The crosstalk so implied between oncogenic UV-induced mutations, defective host immunity, and β-HPV-dependent stromal-epithelial signaling suggests that immunosuppressants such as calcineurin inhibitors intensify mitogenic signalling in TP53-mutant keratinocytes while also abrogating immune-dependent Notch-mediated tumor repression. This emerging interplay between solar damage, viral homeostasis and immune control makes it timely to reappraise strategies for managing skin SCCs in transplant patients.

Targeting human papillomavirus genome replication for antiviral drug discovery

Human papillomavirus (HPV) infections are a major human health problem; they are the cause of recurrent benign warts and of several cancers of the anogenital tract and head and neck region. Although there are two prophylactic HPV vaccines that could, if used universally, prevent as many as two-thirds of HPV-induced cancers, as well as several cytotoxic and immunomodulatory agents for localized treatment of infections, there are currently no HPV antiviral drugs in our arsenal of therapeutic agents. This review examines the status of past and ongoing research into the development of HPV antivirals, focused primarily upon approaches targeting the replication of the viral genome. The only HPV enzyme, E1, is a DNA helicase that interfaces with the cellular DNA replication machinery to replicate the HPV genome. To date, searches for small molecule inhibitors of E1 for use as antivirals have met with limited success. The lack of other viral enzymes has meant that the search for antivirals has shifted to a large degree to the modulation of protein-protein interactions. There has been some success in identifying small molecule inhibitors targeting interactions between HPV proteins but with activity against a small subset of viral types only. As noted in this review, it is thought that targeting E1 interactions with cellular replication proteins may provide inhibitors with broader activity against multiple HPV types. Herein, we outline the steps in HPV DNA replication and discuss those that appear to provide the most advantageous targets for the development of anti-HPV therapeutics.

Modulation of apoptotic pathways by human papillomaviruses (HPV): mechanisms and implications for therapy

The ability of the host to trigger apoptosis in infected cells is perhaps the most powerful tool by which viruses can be cleared from the host organism. To avoid elimination by this mechanism, human papillomaviruses (HPV) have developed several mechanisms that enable the cells they infect to elude both extrinsic and intrinsic apoptosis. In this manuscript, we review the current literature regarding how HPV-infected cells avoid apoptosis and the molecular mechanisms involved in these events. In particular, we will discuss the modifications in intrinsic and extrinsic apoptotic pathways caused by proteins encoded by HPV early genes. Many of the current efforts regarding anti-cancer drug development are focused on directing tumor cells to undergo apoptosis. However, the ability of HPV-infected cells to resist apoptotic signals renders such therapies ineffective. Possible mechanisms for overcoming the resistance of HPV-infected tumor cells to anticancer drugs will be discussed.

Controversies surrounding human papilloma virus infection, head & neck vs oral cancer, implications for prophylaxis and treatment

Head & Neck Cancer (HNC) represents the sixth most common malignancy worldwide and it is historically linked to well-known behavioural risk factors, i.e., tobacco smoking and/or the alcohol consumption. Recently, substantial evidence has been mounting that Human Papillomavirus (HPV) infection is playing an increasing important role in oral cancer. Because of the attention and clamor surrounding oral HPV infection and related cancers, as well as the use of HPV prophylactic vaccines, in this invited perspective the authors raise some questions and review some controversial issues on HPV infection and its role in HNC, with a particular focus on oral squamous cell carcinoma. The problematic definition and classification of HNC will be discussed, together with the characteristics of oral infection with oncogenic HPV types, the frequency of HPV DNA detection in HNC, the location of HPV-related tumours, the severity and prognosis of HPV-positive HNC, the diagnosis of oral HPV infection, common routes of oral infection and the likelihood of oro-genital HPV transmission, the prevention of HPV infection and novel therapeutic approaches.