Antiproliferative effects of interferon-alphaCon1 on ovarian clear cell adenocarcinoma in vitro and in vivo

Characterization of Mutational Status, Spheroid Formation, and Drug Response of a New Genomically-Stable Human Ovarian Clear Cell Carcinoma Cell Line, 105C

Ovarian clear cell carcinoma (OCCC) is a rare subtype of gynecological cancer for which well-characterized and authenticated model systems are scarce. We provide an extensive characterization of ‘105C’, a cell line generated from an adenocarcinoma of the clear cell histotype using targeted next-generation sequencing, cytogenetic microarrays, along with analyses of AKT/mTOR signaling. We report that that the 105C cell line is a bona fide OCCC cell line, carrying PIK3CA, PTEN, and ARID1A gene mutations, consistent with OCCC, yet maintain a stable genome as reflected by low copy number variation. Unlike KOC-7c, TOV-21G, and RMG-V OCCC lines also mutated for the above genes, the 105C cells do not carry mutations in mismatch repair genes. Importantly, we show that 105C cells exhibit greater resistance to mTOR inhibition and carboplatin treatment compared to 9 other OCCC cell lines in 3D spheroid cultures. This resistance may be attributed to 105C cells remaining dormant in suspension culture which surprisingly, contrasts with several other OCCC lines which continue to proliferate in long-term suspension culture. 105C cells survive xenotransplantation but do not proliferate and metastasize. Collectively, we show that the 105C OCCC cell line exhibits unique properties useful for the pre-clinical investigation of OCCC pathobiology.

Host STAT2/type I interferon axis controls tumor growth

The role of STAT2 in mediating the antigrowth effects of type I interferon (IFN) is well-documented in vitro. Yet evidence of IFN-activated STAT2 as having tumor suppressor function in vivo and participation in antitumor immunity is lacking. Here we show in a syngeneic tumor transplantation model that STAT2 reduces tumor growth. Stat2(-/-) mice formed larger tumors compared to wild type (WT) mice. IFN-β treatment of Stat2(-/-) mice did not cause tumor regression. Gene expression analysis revealed a small subset of immunomodulatory genes to be downregulated in tumors established in Stat2(-/-) mice. Additionally, we found tumor antigen cross-presentation by Stat2(-/-) dendritic cells to T cells to be impaired. Adoptive transfer of tumor antigen specific CD8(+) T cells primed by Stat2(-/-) dendritic cells into tumor-bearing Stat2(-/-) mice did not induce tumor regression with IFN-β intervention. We observed that an increase in the number of CD4(+) and CD8(+) T cells in the draining lymph nodes of IFN-β-treated tumor-bearing WT mice was absent in IFN-β treated Stat2(-/-) mice. Thus our study provides evidence for further evaluation of STAT2 function in cancer patients receiving type I IFN based immunotherapy.

Pegylated interferon-α2a inhibits proliferation of human liver cancer cells in vitro and in vivo

Purpose

We investigated the effects of pegylated interferon-α2a (PEG-IFN-α2a) on the growth of human liver cancer cells.

Methods

The effect of PEG-IFN-α2a on the proliferation of 13 liver cancer cell lines was investigated invitro. Cells were cultured with medium containing 0–4,194 ng/mL of PEG-IFN-α2a, and after 1, 2, 3, or 4 days of culture, morphologic observation and growth assay were performed. After hepatocellular carcinoma (HCC) cells (HAK-1B and KIM-1) were transplanted into nude mice, various doses of PEG-IFN-α2a were subcutaneously administered to the mice once a week for 2 weeks, and tumor volume, weight, and histology were examined.

Results

PEG-IFN-α2a inhibited the growth of 8 and 11 cell lines in a time- and dose-dependent manner, respectively, although the 50% growth inhibitory concentrations of 7 measurable cell lines on Day 4 were relatively high and ranged from 253 ng/mL to 4,431 ng/mL. Various levels of apoptosis induction were confirmed in 8 cell lines. PEG-IFN-α2a induced a dose-dependent decrease in tumor volume and weight, and a significant increase of apoptotic cells in the tumor. Subcutaneous administration of clinical dose for chronic hepatitis C (3 μg/kg, 0.06 μg/mouse) was effective and induced about 30-50% reduction in the tumor volume and weight as compared with the control.

Conclusions

Although invitro anti-proliferative effects of PEG-IFN-α2a were relatively weak, PEG-IFN-α2a induced strong anti-tumor effects on HCC cells invivo. The data suggest potential clinical application of PEG-IFN-α2a for the prevention and treatment of HCC.

Potential role of mTORC2 as a therapeutic target in clear cell carcinoma of the ovary

The goal of this study was to examine the role of mTOR complex 2 (mTORC2) as a therapeutic target in ovarian clear cell carcinoma (CCC), which is regarded as an aggressive, chemoresistant histologic subtype. Using tissue microarrays of 98 primary ovarian cancers [52 CCCs and 46 serous adenocarcinomas (SAC)], activation of mTORC2 was assessed by immunohistochemistry. Then, the growth-inhibitory effect of mTORC2-targeting therapy, as well as the role of mTORC2 signaling as a mechanism for acquired resistance to the mTOR complex 1 (mTORC1) inhibitor RAD001 in ovarian CCC, were examined using two pairs of RAD001-sensitive parental (RMG2 and HAC2) and RAD001-resistant CCC cell lines (RMG2-RR and HAC2-RR). mTORC2 was more frequently activated in CCCs than in SACs (71.2% vs. 45.7%). Simultaneous inhibition of mTORC1 and mTORC2 by AZD8055 markedly inhibited the proliferation of both RAD001-sensitive and -resistant cells in vitro. Treatment with RAD001 induced mTORC2-mediated AKT activation in RAD001-sensitive CCC cells. Moreover, increased activation of mTORC2-AKT signaling was observed in RAD001-resistant CCC cells compared with the respective parental cells. Inhibition of mTORC2 during RAD001 treatment enhanced the antitumor effect of RAD001 and prevented CCC cells from acquiring resistance to RAD001. In conclusion, mTORC2 is frequently activated, and can be a promising therapeutic target, in ovarian CCCs. Moreover, mTORC2-targeted therapy may be efficacious in a first-line setting as well as for second-line treatment of recurrent disease developing after RAD001-treatment.

Interferon (alpha, beta and omega) receptor 2 is a prognostic biomarker for lung cancer

OBJECTIVES

It has been reported that the type I interferon receptor subunit, interferon (alpha, beta and omega) receptor 2 (IFNAR2), is overexpressed in several malignancies, primarily adenocarcinomas (ADCs); however, the biological significance of IFNAR2 in human lung cancer has not yet been studied.

METHODS

Immunohistochemical analysis of 113 surgically resected lung specimens was performed, and the results were evaluated in association with clinical variables, including survival. Serum concentrations of IFNAR2 were also determined by an enzyme-linked immunosorbent assay in 157 lung cancer patients and 164 healthy volunteers.

RESULTS

IFNAR2 overexpression was observed in all histological types of lung cancer examined. Furthermore, strong IFNAR2 expression was associated with shorter progression-free survival (PFS) and overall survival (OS) (p < 0.0001 and p = 0.0110, respectively) in non-small cell lung cancer patients. Multivariate analyses confirmed its independent prognostic value for PFS and OS (p < 0.0001 and p = 0.0222, respectively). IFNAR2 serum levels were also significantly higher in lung cancer patients than in healthy volunteers (p < 0.0001).

CONCLUSIONS

IFNAR2 overexpression was observed in various histological types of lung cancer, and appears to be associated with lung cancers that behave aggressively. The results of this study strongly support the potential of IFNAR2 to be a prognostic biomarker for lung cancer.

Expression of an IRF-3 fusion protein and mouse estrogen receptor, inhibits hepatitis C viral replication in RIG-I-deficient Huh 7.5 cells

Interferon Regulatory Factor-3 (IRF-3) plays a central role in the induction of interferon (IFN) production and succeeding interferon-stimulated genes (ISG) expression en route for restraining hepatitis C virus (HCV) infection. Here, we established a stable Huh7.5-IRF3ER cell line expressing a fusion protein of IRF-3 and mouse estrogen receptor (ER) to examine IFN production and anti-HCV effects of IRF-3 in retinoic acid inducible-gene-I (RIG-I) deficient Huh 7.5 cells. Homodimerization of the IRF-3ER fusion protein was detected by Western blotting after treatment with the estrogen receptor agonist 4-hydrotamoxifen (4-HT) in Huh7.5-IRF3ER cells. Expression of IFN-α, IFN-β, and their inhibitory effects on HCV replication were demonstrated by real-time polymerase chain reaction (PCR). Peak expression of IFN-α and IFN-β was achieved 24-hours post 4-HT treatment, coinciding with the appearance of phosphorylated signal transducer and activator of transcription (STAT) proteins. Additionally, HCV viral replication declined in time-dependent fashion. In previous studies, a novel IFN-mediated pathway regulating expression of 1-8U and heterogeneous nuclear ribonucleoprotein M (hnRNP M) inhibited HCV internal ribosomal entry site (IRES)-dependent translation. When expression of ISGs such as 1-8U and hnRNP M were measured in 4-HT-treated Huh7.5-IRF3ER cells, both genes were positively regulated by activation of the IRF-3ER fusion protein. In conclusion, the anti-HCV effects of IRF-3ER homodimerization inhibited HCV RNA replication as well as HCV IRES-dependent translation in Huh7.5-IRF3ER cells. The results of this study indicate that IRF-3ER homodimerization is a key step to restore IFN expression in Huh7.5-IRF3ER cells and in achieving its anti-HCV effects.

The activity of trabectedin as a single agent or in combination with everolimus for clear cell carcinoma of the ovary

PURPOSE

The objective of this study was to evaluate the antitumor efficacy of trabectedin in clear cell carcinoma (CCC) of the ovary, which is regarded as an aggressive, chemoresistant, histologic subtype.

EXPERIMENTAL DESIGN

Using 6 human ovarian cancer cell lines (3 CCC and 3 serous adenocarcinomas), the antitumor effects of trabectedin were examined in vitro, and we compared its activity according to histology. We next examined the antitumor activity of trabectedin in both cisplatin-resistant and paclitaxel-resistant CCC cells in vitro. Then, the in vivo effects of trabectedin were evaluated using mice inoculated with CCC cell lines. Using 2 pairs of trabectedin-sensitive parental and trabectedin-resistant CCC sublines, we investigated the role of mTOR in the mechanism of acquired resistance to trabectedin. Finally, we determined the effect of mTOR inhibition by everolimus on the antitumor efficacy of trabectedin in vitro and in vivo.

RESULTS

Trabectedin showed significant antitumor activity toward chemosensitive and chemoresistant CCC cells in vitro. Mouse xenografts of CCC cells revealed that trabectedin significantly inhibits tumor growth. Greater activation of mTOR was observed in trabectedin-resistant CCC cells than in their respective parental cells. The continuous inhibition of mTOR significantly enhanced the therapeutic efficacy of trabectedin and prevented CCC cells from acquiring resistance to trabectedin.

CONCLUSION

Trabectedin is a promising agent for CCC as a first-line chemotherapy and as a second-line treatment of recurrent CCC that had previously been treated with cisplatin or paclitaxel. Moreover, trabectedin combined with everolimus may be more efficacious for the management of CCC.

Vascular endothelial growth factor is a promising therapeutic target for the treatment of clear cell carcinoma of the ovary

This study examines the role of vascular endothelial growth factor (VEGF) as a therapeutic target in clear cell carcinoma (CCC) of the ovary, which has been regarded as a chemoresistant histologic subtype. Immunohistochemical analysis using tissue microarrays of 98 primary ovarian cancers revealed that VEGF was strongly expressed both in early-stage and advanced-stage CCC of the ovary. In early-stage CCCs, patients who had tumors with high levels of VEGF had significantly shorter survival than those with low levels of VEGF. In vitro experiments revealed that VEGF expression was significantly higher in cisplatin-refractory human CCC cells (RMG1-CR and KOC7C-CR), compared with the respective parental cells (RMG1 and KOC7C) in the presence of cisplatin. In vivo treatment with bevacizumab markedly inhibited the growth of both parental CCC cell-derived (RMG1 and KOC7C) and cisplatin-refractory CCC cell-derived (RMG1-CR and KOC7C-CR) tumors as a result of inhibition of tumor angiogenesis. The results of the current study indicate that VEGF is frequently expressed and can be a promising therapeutic target in the management of CCC. Bevacizumab may be efficacious not only as a first-line treatment but also as a second-line treatment of recurrent disease in patients previously treated with cisplatin.

Identification of an ovarian clear cell carcinoma gene signature that reflects inherent disease biology and the carcinogenic processes

Ovarian clear cell carcinoma (OCCC) shows unique clinical features including an association with endometriosis and poor prognosis. We previously reported that the contents of endometriotic cysts, especially high concentrations of free iron, are a possible cause of OCCC carcinogenesis through iron-induced persistent oxidative stress. In this study, we conducted gene expression microarray analysis using 38 ovarian cancer cell lines and identified genes commonly expressed in both OCCC cell lines and clinical samples, which comprise an OCCC gene signature. The OCCC signature reproducibly predicts OCCC specimens in other microarray data sets, suggesting that this gene profile reflects the inherent biological characteristics of OCCC. The OCCC signature contains known markers of OCCC, such as hepatocyte nuclear factor-1beta (HNF-1beta) and versican (VCAN), and other genes that reflect oxidative stress. Expression of OCCC signature genes was induced by treatment of immortalized ovarian surface epithelial cells with the contents of endometriotic cysts, indicating that the OCCC signature is largely dependent on the tumor microenvironment. Induction of OCCC signature genes is at least in part epigenetically regulated, as we found hypomethylation of HNF-1beta and VCAN in OCCC cell lines. This genome-wide study indicates that the tumor microenvironment induces specific gene expression profiles that contribute to the development of distinct cancer subtypes.

mTOR is a promising therapeutic target both in cisplatin-sensitive and cisplatin-resistant clear cell carcinoma of the ovary

PURPOSE

Mammalian target of rapamycin (mTOR) plays a central role in cell proliferation and is regarded as a promising target in cancer therapy, including for ovarian cancer. This study aimed to examine the role of mTOR as a therapeutic target in clear cell carcinoma of the ovary, which is regarded as an aggressive, chemoresistant histologic subtype.

EXPERIMENTAL DESIGN

Using tissue microarrays of 98 primary ovarian cancers (52 clear cell carcinomas and 46 serous adenocarcinomas), the expression of phospho-mTOR was assessed by immunohistochemistry. Then, the growth-inhibitory effect of mTOR inhibition by RAD001 (everolimus) was examined using two pairs of cisplatin-sensitive parental (RMG1 and KOC7C) and cisplatin-resistant human clear cell carcinoma cell lines (RMG1-CR and KOC7C-CR) both in vitro and in vivo.

RESULTS

Immunohistochemical analysis showed that mTOR was more frequently activated in clear cell carcinomas than in serous adenocarcinomas (86.6% versus 50%). Treatment with RAD001 markedly inhibited the growth of both RMG1 and KOC7C cells both in vitro and in vivo. Increased expression of phospho-mTOR was observed in cisplatin-resistant RMG1-CR and KOC7C-CR cells, compared with the respective parental cells. This increased expression of phospho-mTOR in cisplatin-resistant cells was associated with increased activation of AKT. RMG1-CR and KOC7C-CR cells showed greater sensitivity to RAD001 than did parental RMG1 and KOC7C cells, respectively, in vitro and in vivo.

CONCLUSION

mTOR is frequently activated in clear cell carcinoma and can be a promising therapeutic target in the management of clear cell carcinoma. Moreover, mTOR inhibition by RAD001 may be efficacious as a second-line treatment of recurrent disease in patients previously treated with cisplatin.

Decreased type I interferon receptor-soluble isoform in antiretroviral-treated HIV-positive children

We developed a real-time PCR assay to simultaneously measure the mRNA level of type I interferon (IFN) receptor (IFNAR) components in peripheral blood cells of children with chronic immune stimulation due to HIV infection. All patients were undergoing antiretroviral therapy and were divided into two groups on the basis of the induction of MxA mRNA, a marker of type I IFN bioactivity. We found that IFNAR-2 subunit mRNA was higher than that of the IFNAR-1 subunit, that the mRNA for the IFNAR-2.2 functional isoform was more expressed than that for the truncated IFNAR-2.1 isoform, and both were much more represented than that of the IFNAR-2.3 soluble isoform. We also demonstrated that soluble isoform mRNA was significantly diminished in the subgroup of patients with MxA mRNA below the cutoff value (determined as the 99th percentile of MxA measured in healthy controls). These results suggest that downregulation of the soluble receptor isoform, which would not compete with the functional isoform for binding to the target cytokine, would give type I IFN, eventually induced in these patients in the case of viral reactivation, the opportunity to promptly exert its antiviral activity.

Effect of exogenous interferon and an interferon inducer on western equine encephalitis virus disease in a hamster model

Mice are used as models for western equine encephalitis virus (WEEV) infection, but high mortality is generally only seen with intracranial or intranasal challenge, while peripheral inoculation results in approximately 50% mortality and is not dose-dependent. Hamsters were therefore studied as a model for WEEV infection. Hamsters were highly sensitive to intraperitoneal (i.p.) infection with WEEV. Disease progression was rapid, and virus titers in serum, brain, liver, and kidney of infected hamsters peaked between 2 and 4 days post-virus inoculation (dpi). Foci of virus infection were detected in neurons of the cerebral cortex and midbrain. Pre-treatment i.p. with either interferon alfacon-1 (5 microg/kg/day) or with Ampligen (3.2 mg/kg/day) resulted in complete survival, reduced brain titers, and improved weight gain. This model of WEEV infection in hamsters appears to serve as a suitable model for the evaluation of potential therapeutic agents for the treatment of WEE disease.

Growth inhibitory effects of pegylated IFN alpha-2b on human liver cancer cells in vitro and in vivo

PURPOSE

We investigated the effects of pegylated IFN-alpha2b (PEG-IFN-alpha2b) on the growth of human liver cancer cells.

METHODS

The effect of PEG-IFN-alpha2b on the proliferation of 13 liver cancer cell lines was investigated in vitro. Chronological changes in growth and IFN-alpha receptor-2 (IFNAR-2) expression were monitored in hepatocellular carcinoma (HCC) cells (HAK-1B) cultured with PEG-IFN-alpha2b. After HAK-1B cells were transplanted into nude mice, various doses of PEG-IFN-alpha2b or IFN-alpha2b were administered, and tumor volume, weight, histology, and IFNAR-2 expression were examined.

RESULTS

PEG-IFN-alpha2b inhibited the growth of nine cell lines with apoptosis in a dose- and time-dependent manner. Continuous contact with PEG-IFN-alpha2b induced time-dependent growth inhibition and down-regulation of IFNAR-2 expression. PEG-IFN-alpha2b induced a dose-dependent decrease in tumor volume and weight, a significant increase of apoptotic cells, and a decrease in IFNAR-2 expression in the tumor. The clinical dose for chronic hepatitis C was also effective. The antitumor effect of PEG-IFN-alpha2b was significantly stronger than that of non-PEG-IFN-alpha2b in vivo.

CONCLUSIONS

Continuous contact with PEG-IFN-alpha2b induces strong antitumor effects and the down-regulation of IFNAR-2 in HCC cells. The data suggest potential clinical application of PEG-IFN-alpha2b for the prevention and treatment of HCC.

Adenovirus delivery provides extended interferon-alpha exposure and augments treatment of metastatic carcinoma

Type I interferons (e.g. IFNalpha2b) have been successfully used to treat a variety of hematological malignancies, but have not been efficacious for treatment of most solid tumors. We tested the hypothesis that delivery of type I interferon utilizing recombinant adenovirus (rAd) vectors may improve treatment efficacy of metastatic carcinomas by providing increased interferon exposure resulting from continuous transgene expression. Treatment of mice with a rAd-vector expressing hybrid-IFN (rAd-IFNalpha2alpha1) inhibited 4T1 mammary carcinoma tumor growth and induced tumor regression in a dose-dependent manner. Moreover, rAd-IFNalpha2alpha1 treatment reduced hepatic and pulmonary metastatic burden. A comparison of local and systemic routes of administration demonstrated that intratumoral delivery of rAd-IFNalpha2alpha1 was sufficient for inhibition of tumor growth. Moreover, it reduced toxicity associated with high-dose systemic IFNalpha2alpha1 exposure. Interestingly, antitumor activity following intratumoral treatment was due, in part, to the immunostimulatory capacity of the rAd vector component. Furthermore, systemic administration of rAd-IFNalpha2alpha1 potentiated the immunotherapeutic effect induced by local intralesional delivery of empty-rAd vector. These results suggest continuous interferon-alpha exposure may provide improved antitumor responses for metastatic carcinomas. Additionally, immunostimulatory responses induced by rAd-IFNalpha2alpha1 may mitigate the immune-evasive tumor microenvironment.

Antiproliferative effects of 5-fluorouracil and interferon-alpha in combination on a hepatocellular carcinoma cell line in vitro and in vivo

BACKGROUND AND AIM

We investigated the antiproliferative effects of interferon-alpha (IFN-alpha) and 5-fluorouracil (5-FU) in combination on a hepatocellular carcinoma (HCC) cell line.

METHOD

In the in vitro study, IFN-alpha and/or 5-FU was added to the culture of the poorly differentiated-type HCC cell line, HAK-1B, and their antiproliferative effects and additional or synergic effects in combination treatment were examined. In the in vivo study, HAK-1B cells were transplanted into nude mice and the changes in tumor volume and weight, apoptosis, BrdU and cyclin A positive cells, and artery-like blood vessels were investigated. Expressions of angiogenesis factors and IFN-alpha receptor (IFNAR-2) were examined in the developed tumors.

RESULTS

In vitro growth of HAK-1B cells was suppressed dose-dependently to 5-FU, but the addition of IFN-alpha did not induce additional or synergic effects. In vivo growth in terms of tumor diameter and weight was suppressed at most in the IFN-alpha + 5-FU (combination) group, that is, the tumor volume became 29.3% and the tumor weight became 54.7% of the control. In the combination group, numbers of BrdU-positive S-phase cells and cyclin A positive cells increased together with the increase in apoptotic cells, but there was no significant relation between the tumor shrinkage effects and angiogenesis factors or artery-like blood vessels. In the combination group, INFAR-2 decreased significantly in comparison to the other groups.

CONCLUSION

The synergic growth-suppression effects in the current in vivo study using the combination treatment are attributable to the enhanced induction of S-phase arrest and of apoptosis.