Retinoblastoma RB94 enhances radiation treatment of head and neck squamous cell carcinoma

Nanomedicine-Based Gene Delivery for a Truncated Tumor Suppressor RB94 Promotes Lung Cancer Immunity

Because lung cancer remains the most common and lethal of cancers, novel therapeutic approaches are urgently needed. RB94 is a truncated form of retinoblastoma tumor suppressor protein with elevated anti-tumor efficacy. Our investigational nanomedicine (termed scL-RB94) is a tumor-targeted liposomal formulation of a plasmid containing the gene encoding RB94. In this research, we studied anti-tumor and immune modulation activities of scL-RB94 nanocomplex in preclinical models of human non-small cell lung cancer (NSCLC). Systemic treatment with scL-RB94 of mice bearing human NSCLC tumors significantly inhibited tumor growth by lowering proliferation and increasing apoptosis of tumor cells in vivo. scL-RB94 treatment also boosted anti-tumor immune responses by upregulating immune recognition molecules and recruiting innate immune cells such as natural killer (NK) cells. Antibody-mediated depletion of NK cells blunted the anti-tumor activity of scL-RB94, suggesting that NK cells were crucial for the observed anti-tumor activity in these xenograft models. Treatment with scL-RB94 also altered the polarization of tumor-associated macrophages by reducing immune-suppressive M2 macrophages to lower immune suppression in the tumor microenvironment. Collectively, our data suggest that the efficacy of scL-RB94 against NSCLC is due to an induction of tumor cell death as well as enhancement of innate anti-tumor immunity.

Approaches for Head and Neck Cancer Research - Current Status and the Way Forward

Head and neck cancers (HNCs) are seeing an increasing trend in their prevalence among both genders and are the seventh most common cancer type occurring at the global level. Studies addressing both the cancer cell physiology and individual differences in response to a specific treatment modality should be understood for arriving at effective treatment and management of the HNCs. In this article, we discuss the trends in HNC research and their various approaches starting from 2D in vitro models, which are the traditional experimental materials to recently established Cancer-Tissue Originated Spheroids (CTOS) distinctly contributing towards personalized or precision medicine.

Acute alcohol consumption-induced let-7a inhibition exacerbates hepatic apoptosis by regulating Rb1 in mice

Alcohol consumption is a critical risk factor for hepatic pathogenesis, including alcoholic liver diseases (ALD), but implications of alcohol-induced dysregulation of microRNA (miRNA) in ALD pathogenesis are not completely understood. In the present study, C57BL/6J male mice were treated with saline (CON; oral gavage; n = 8) or alcohol (EtOH; 3 g/kg body weight; oral gavage; n = 8) for 7 days. A total of 599 miRNAs and 158 key mRNAs related to fatty liver and hepatotoxicity pathways were assessed in mice liver tissues. The mRNA expression datasets were then utilized to predict interactions with miRNAs that were changed by alcohol consumption. Predicted miRNA-mRNA interactions were validated using in vitro miRNA transfection experiments. The results showed that let-7a was significantly decreased in the EtOH group and Rb1 mRNA was predicted as a target gene. This was further supported by an inverse correlation of RB1 and let-7a expression in mice liver tissue. Additionally, key protein expressions involved in RB1-apoptosis axis [i.e., p73, cleaved CASP-3 (cCASP-3), and cCASP-7] showed a trend of increase in the EtOH mice; this was also confirmed by capase-3 enzyme activity and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling assay in livers of mice that had consumed alcohol. In line with our in vivo observations, alcohol treatment suppressed the let-7a expression and subsequently upregulated p73, cCASP-3, and cCASP-7 protein expressions in mice hepatocytes. Additional proteins in the apoptosis regulatory pathway (i.e., MDM2-p53 axis) were significantly changed in response to let-7a suppression in the cells. Taken together, the current study provides mechanistic evidence that alcohol consumption-induced let-7a suppression results in the upregulation of RB1, thereby promoting hepatic apoptosis through induction of pro-apoptotic proteins (e.g., p73), and by, at least in part, preventing MDM2-mediated p53 degradation.

Nicotinic Acetylcholine Receptor Subunit Alpha-5 Promotes Radioresistance via Recruiting E2F Activity in Oral Squamous Cell Carcinoma

Radiotherapy is commonly used to treat patients with oral squamous cell carcinoma (OSCC), but a subpopulation of OSCC patients shows a poor response to irradiation treatment. Therefore, identifying a biomarker to predict the effectiveness of radiotherapy in OSCC patients is urgently needed. In silico analysis of public databases revealed that upregulation of CHRNA5, the gene encoding nicotinic acetylcholine receptor subunit alpha-5, is extensively detected in primary tumors compared to normal tissues and predicts poor prognosis in OSCC patients. Moreover, CHRNA5 transcript level was causally associated with the effective dose of irradiation in a panel of OSCC cell lines. Artificial silencing of CHRNA5 expression enhanced, but nicotine reduced, the radiosensitivity of OSCC cells. Gene set enrichment analysis demonstrated that the E2F signaling pathway is highly activated in OSCC tissues with high levels of CHRNA5 and in those derived from patients with cancer recurrence after radiotherapy. CHRNA5 knockdown predominantly suppressed E2F activity and decreased the phosphorylation of the Rb protein; however, nicotine treatment dramatically promoted E2F activity and increased Rb phosphorylation, which was mitigated after CHRNA5 knockdown in OSCC cells. Notably, the signature combining increased mRNA levels of CHRNA5 and the E2F signaling gene set was associated with worse recurrence-free survival probability in OSCC patients recorded to be receiving radiotherapy. Our findings suggest that CHRNA5 is not only a useful biomarker for predicting the effectiveness of radiotherapy but also a druggable target to enhance the cancericidal effect of irradiation on OSCC.

Role of adenovirus-mediated retinoblastoma 94 in the treatment of human non-small cell lung cancer

Non-small cell lung cancer (NSCLC) remains the leading cause of cancer-related mortality despite the fact that great advances have been made in therapeutic treatment methods. Therefore, in the present study, the role of adenovirus-mediated retinoblastoma 94 (Ad-RB94) gene therapy in NSCLC was investigated. Following treatment with Ad-RB94, the proportion of A549 cells in the G2/M phase was increased. In the mouse xenograft model, the overexpression of RB94 inhibited the tumor growth compared with the control group and the Ad-LacZ-treated group. In the transplanted tumors, the overexpression of RB94 induced the apoptosis of tumors as well as an increase in the mRNA levels of cyclinB1. In conclusion, the results of the present study suggested that RB94 may effectively inhibit NSCLC tumor cell growth by inducing G2/M cell cycle arrest and apoptosis, indicating that RB94 may be a promising candidate for adjuvant therapy with radiation or chemotherapy in NSCLC.

The retinoblastoma protein induces apoptosis directly at the mitochondria

The retinoblastoma protein gene RB-1 is mutated in one-third of human tumors. Its protein product, pRB (retinoblastoma protein), functions as a transcriptional coregulator in many fundamental cellular processes. Here, we report a nonnuclear role for pRB in apoptosis induction via pRB's direct participation in mitochondrial apoptosis. We uncovered this activity by finding that pRB potentiated TNFα-induced apoptosis even when translation was blocked. This proapoptotic function was highly BAX-dependent, suggesting a role in mitochondrial apoptosis, and accordingly, a fraction of endogenous pRB constitutively associated with mitochondria. Remarkably, we found that recombinant pRB was sufficient to trigger the BAX-dependent permeabilization of mitochondria or liposomes in vitro. Moreover, pRB interacted with BAX in vivo and could directly bind and conformationally activate BAX in vitro. Finally, by targeting pRB specifically to mitochondria, we generated a mutant that lacked pRB's classic nuclear roles. This mito-tagged pRB retained the ability to promote apoptosis in response to TNFα and also additional apoptotic stimuli. Most importantly, induced expression of mito-tagged pRB in Rb(-/-);p53(-/-) tumors was sufficient to block further tumor development. Together, these data establish a nontranscriptional role for pRB in direct activation of BAX and mitochondrial apoptosis in response to diverse stimuli, which is profoundly tumor-suppressive.

Kaposi's sarcoma-associated herpesvirus lana2 protein interacts with the pocket proteins and inhibits their sumoylation

The pocket proteins retinoblastoma protein (pRb), p107 and p130 are the key targets of oncoproteins expressed by DNA tumor viruses. Some of these viral proteins contain an LXCXE motif that mediates the interaction with the three pocket proteins and the inhibition of the pRb SUMOylation. Kaposi's sarcoma herpesvirus (KSHV) contains at least two proteins that can regulate pRb function but, so far, a KSHV-encoded protein targeting p107 and p130 has not been identified. Here, we show that the KSHV latent protein LANA2 binds to pRb, p107 and p130. LANA2 contains an LXCXE motif that is required for bypassing pRb-mediated cell-cycle arrest and for inhibiting pRb SUMOylation. Finally, we demonstrate that, in addition to pRb, both p107 and p130 can be SUMOylated, and this modification is also inhibited by LANA2 in an LXCXE-dependent manner. These results demonstrate, for the first time, the SUMOylation of p107 or p130 and, so far, they represent the first example of a KSHV protein able to interact with the three pocket proteins and to inhibit their conjugation to SUMO.

Experimental research of RB94 gene transfection into retinoblastoma cells using ultrasound-targeted microbubble destruction

The purpose of this study was to explore the transfection of the recombinant expression plasmid pEGFP-C1/RB94 into human retinoblastoma cells (HXO-Rb44) using ultrasound-targeted microbubble destruction (UTMD). pEGFP-C1/RB94 was transfected into HXO-Rb44 in vitro by UTMD, with liposome as the positive control. After 24 to 72 h, the expression of the reporter gene enhanced green fluorescent protein (EGFP) was observed using fluorescent microscopy and flow cytometry. The cell viability of HXO-Rb44 was measured by a MTT assay. The mRNA and proteins of RB94, caspase-3 and Bax were analyzed by reverse transcription polymerase chain reaction (RT-PCR) and Western blot. Moreover, the apoptosis rate and cell cycle progression of the cells were detected by flow cytometry. This study demonstrated that UTMD can enhance the transfection efficiency of RB94, which has an obvious impact on the inhibition of the growth process of retinoblastoma cells, suggesting that the combination of UTMD and RB94 compounds might be a useful tool for use in the gene therapy of retinoblastoma.

Retinoblastoma 94 enhances radiation treatment of esophageal squamous cell carcinoma in vitro and in vivo

We performed the study to investigate whether adenovirus-mediated retinoblastoma 94 (RB94) gene transfer could enhance radiation treatment of esophageal squamous cell carcinoma (ESCC) in vitro and in vivo. ESCC cells (Kyse150 cell line) were cultivated in vitro and tumors originated from the cell line were propagated as xenografts in nude mice. Treatment with Ad-RB94 and/or ionizing radiation (IR) was carried out both in vitro and in vivo with Ad-LacZ control vector and blank control. Cell viability, cell cycle distribution, cell apoptosis, tumor growth and transfected gene expression were evaluated and tumor degeneration was analyzed. The data of quantification real-time PCR assays and immunohistochemistry staining using RB antibody indicated that RB94 was efficiently transfected into Kyse150 cells. In vitro, data of cell growth assay indicated that treatment with Ad-RB94 improved radiation treatment of Kyse150 cells. Tumor xenograft studies, pathological analysis of H.E. staining and Ki67 staining suggested transfecting RB94 enhanced tumor regression induced by radiation treatment in vivo. In addition, data of Annexin V, TUNEL and cell cycle distribution assays proposed combination treatment effectively induced cell apoptosis and cell cycle arresting in G2/M phase. In conclusion, transferring RB94 gene by the adenoviral vector enhances radiation treatment of ESCC.

Molecular disruption of NBS1 with targeted gene delivery enhances chemosensitisation in head and neck cancer

BACKGROUND

a fibroblast growth factor 2 (FGF2)-targeted adenoviral system can alter viral tropism and allow for improved transduction and reduced systemic toxicity. This study is to investigate if the FGF2-targeted adenoviral mutant Nijmegen breakage syndrome 1 (FGF2-Ad-NBS1) gene transfer can enhance cisplatin chemosensitisation not only by targeting DNA repair, but also through the induction of antiangiogenesis, whereas at the same time reducing toxicities in treating head and neck squamous cell carcinoma (HNSCC).

METHODS

the human HNSCC cell line was treated in vitro and in a nude mouse xenograft model. We conducted verification of binding ability of mutant NBS1 and downregulation of MRN complex, evaluation of transduction efficiency and combined antitumour activities. The antiangiogenesis mechanism was also investigated. Finally, we estimated the distribution of adenoviral vector in the liver.

RESULTS

the mutant NBS1 protein retains the binding ability and effectively suppresses the expression level of the MRN in infected cells. Transduction efficiency in vitro and cisplatin chemosensitisation were upregulated. The FGF2-Ad-NBS1 also showed detargeting the viral vectors away from the liver. The downregulation of NF-κB expression was supposed to correlate with increased antiangiogenesis.

CONCLUSIONS

FGF2-targeted adenoviral system enhances the cisplatin chemosensitisation of mutant NBS1 and may avoid viral-associated liver toxicities.

Silk-elastinlike protein polymer hydrogels for localized adenoviral gene therapy of head and neck tumors

Vector dissemination, transient gene expression, and rapid clearance are major obstacles to successful human gene therapy. In this study, we investigated the effect of silk-elastinlike protein polymer (SELP) hydrogels on biodistribution and anticancer efficacy of adenoviral gene therapy in a head and neck cancer model. Transcriptional activities of adenovirus carrying beta-galactosidase (Ad-LacZ) and luciferase (Ad-Luc) reporter genes were evaluated in (nu/nu) mice with head and neck cancer as a function of polymer concentration. Antitumor efficacy of thymidine kinase encoding adenovirus (Ad-Tk) and ganciclovir (GSV) combination was also evaluated. SELP (4 wt %) matrices localized viral release, minimized dissemination to liver, and enhanced reporter gene expression levels by 4-8-fold compared to virus alone. SELP- Ad-Tk with GSV reduced tumor volume significantly compared to the virus alone. SELPs provide a means for temporal and spatial control of viral gene delivery to head and neck tumors.

Proapoptotic function of the retinoblastoma tumor suppressor protein

The retinoblastoma protein (pRB) tumor suppressor blocks cell proliferation by repressing the E2F transcription factors. This inhibition is relieved through mitogen-induced phosphorylation of pRB, triggering E2F release and activation of cell-cycle genes. E2F1 can also activate proapoptotic genes in response to genotoxic or oncogenic stress. However, pRB's role in this context has not been established. Here we show that DNA damage and E1A-induced oncogenic stress promote formation of a pRB-E2F1 complex even in proliferating cells. Moreover, pRB is bound to proapoptotic promoters that are transcriptionally active, and pRB is required for maximal apoptotic response in vitro and in vivo. Together, these data reveal a direct role for pRB in the induction of apoptosis in response to genotoxic or oncogenic stress.