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Antitumor activity of Ad-IU2, a prostate-specific replication-competent adenovirus encoding the apoptosis inducer, TRAIL.

Jiménez JA, Li X, Zhang YP, Bae KH, Mohammadi Y, Pandya P, Kao C, Gardner TA - Cancer Gene Ther. (2009)

Bottom Line: Ad-IU2 induced fivefold greater apoptosis selectively in PSA/PSMA-positive CWR22rv and C4-2 cells than an oncolytic adenoviral control.Furthermore, prolonged infection with Ad-IU2 reversed TRAIL resistance in LNCaP cells.This study shows the potential clinical utility of a PSRCA armed with an apoptosis-inducing ligand.

View Article: PubMed Central - PubMed

Affiliation: Department of Urology, Indiana University School of Medicine, Indianapolis, IN, USA.

ABSTRACT
In this study, we analyzed the preclinical utility and antitumor efficacy of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) delivered by Ad-IU2, a prostate-specific replication-competent adenovirus (PSRCA), against androgen-independent prostate cancer. Through transcriptional control of adenoviral early genes E1a, E1b and E4, as well as TRAIL by two bidirectional prostate-specific enhancing sequences (PSES), the expression of TRAIL and adenoviral replication was limited to prostate-specific antigen (PSA) and prostate-specific membrane antigen (PSMA)-positive cells. Ad-IU2 induced fivefold greater apoptosis selectively in PSA/PSMA-positive CWR22rv and C4-2 cells than an oncolytic adenoviral control. Furthermore, prolonged infection with Ad-IU2 reversed TRAIL resistance in LNCaP cells. Ad-IU2 showed superior killing efficiency in PSA/PSMA-positive prostate cancer cells at doses five- to eight-fold lower than required by a PSRCA to produce a similar effect; however, this cytotoxic effect was not observed in non-prostatic cells. As an enhancement of its therapeutic efficacy, Ad-IU2 exerted a TRAIL-mediated bystander effect through direct cell-to-cell contact and soluble factors such as apoptotic bodies. In vivo, Ad-IU2 markedly suppressed the growth of subcutaneous androgen-independent CWR22rv xenografts compared with a PSRCA at 6 weeks after treatment (3.1- vs 17.1-fold growth of tumor). This study shows the potential clinical utility of a PSRCA armed with an apoptosis-inducing ligand.

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Ad-IU2 suppressed the growth of androgen-independent human prostate tumors in athymic mice. A, subcutaneous androgen-independent CWR22rv xenografts were established in castrated male athymic mice and treated with intratumoral injections of PBS (vehicle control, n = 5), Ad-IU1 (PSRCA control, n = 6) or Ad-IU2 (n = 9). Mean tumor volumes at day 0 and study endpoints are listed. *** = p<0.001 (Ad-IU2 vs. Ad-IU1). B, fold tumor growths for individual mice at the 6-week end-point. Histological appearance of harvested tumors 6 weeks after treatment with PBS (C), Ad-IU1 (D) (large yellow arrows, necrotic centers of oncolysis; small yellow arrows, patches of healthy tumor cells) or Ad-IU2 (E) (large yellow arrows, necrotic centers of oncolysis; small yellow arrows, condensed nuclei) (200× magnification). In situ TUNEL assay detected no apoptosis in tumors treated with PBS (F) or Ad-IU1 (G) and marked apoptosis in tumors treated with Ad-IU2 (H).
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Figure 5: Ad-IU2 suppressed the growth of androgen-independent human prostate tumors in athymic mice. A, subcutaneous androgen-independent CWR22rv xenografts were established in castrated male athymic mice and treated with intratumoral injections of PBS (vehicle control, n = 5), Ad-IU1 (PSRCA control, n = 6) or Ad-IU2 (n = 9). Mean tumor volumes at day 0 and study endpoints are listed. *** = p<0.001 (Ad-IU2 vs. Ad-IU1). B, fold tumor growths for individual mice at the 6-week end-point. Histological appearance of harvested tumors 6 weeks after treatment with PBS (C), Ad-IU1 (D) (large yellow arrows, necrotic centers of oncolysis; small yellow arrows, patches of healthy tumor cells) or Ad-IU2 (E) (large yellow arrows, necrotic centers of oncolysis; small yellow arrows, condensed nuclei) (200× magnification). In situ TUNEL assay detected no apoptosis in tumors treated with PBS (F) or Ad-IU1 (G) and marked apoptosis in tumors treated with Ad-IU2 (H).

Mentions: Previously, we investigated the oncolytic potential of Ad-E4PSESE1a, a PSRCA, which significantly inhibited the growth of CWR22rv xenografts as compared to control virus; however, the response only lasted two weeks, after which the tumor growth exceeded the rate of oncolysis. Rapid intratumoral viral replication and spread peaked at 3 days and was diminished by 1 week after injection.36 For this reason, we determined whether TRAIL could augment the in vivo antitumor effects of a PSRCA. Androgen-independent CWR22rv human prostate cancer xenografts were established SQ in the flanks of castrated athymic male mice and injected with Ad-IU2, Ad-IU1 (replication-competent control) and PBS (vehicle control). Ad-IU2 significantly suppressed the growth of CWR22rv tumor xenografts as compared to Ad-IU1 (3.1-vs. 17.1-fold growth of tumor, respectively). 4 weeks after treatment, Ad-IU1-treated tumors began to fail therapy, resulting in a rebound of tumor growth. On the other hand, Ad-IU2 continued to inhibit tumor growth through the 6-week end-point of the study. Mock-treated mice were sacrificed at 5 weeks due to overwhelming tumor burden (Figure 5A). Of the nine tumors treated with Ad-IU2, six responded favorably with partial regression in four of six or complete regression in two of six tumors. Of the three tumors that failed, two were significantly suppressed compared to Ad-IU1 tumors at 6-weeks (Figure 5B). Given the fact that CWR22rv xenografts are clonogenic, the variation in treatment outcome may be attributed to incomplete tumor infiltration or leakage of virus at the time of injection. Histological examination of PBS-treated tumors revealed healthy cells arranged in normal tumor architecture with significant tumor vasculature in the margins of the growing tumor (Figure 5C). Ad-IU1-treated tumors were characterized by scattered necrotic patches surrounded by healthy tumor cells, indicative of incomplete oncolysis due to limited viral replication and propagation throughout the entire tumor mass (Figure 5D). Although patches of healthy tumor cells remained within the Ad-IU2-treated tumors, necrotic centers of viral replication and oncolysis were more diffuse throughout the entire tumor. Furthermore, cells immediately surrounding the necrotic centers appeared unhealthy with condensed nuclei, indicating spread of the cytotoxic and apoptotic effect beyond the necrotic centers (Figure 5E). To determine whether apoptosis contributed significantly to the tumor killing process, in situ TUNEL assays were performed on the tumor sections. No apoptotic nuclei were detected in the control tumors (Figure 5F-G). On the other hand, Ad-IU2-treated tumors displayed marked apoptosis in the margins surrounding necrotic centers of oncolysis (Figure 5H). These data suggest that TRAIL potentiated the in vivo killing power of a PSRCA through apoptosis induction in cells beyond the margin of viral replication.


Antitumor activity of Ad-IU2, a prostate-specific replication-competent adenovirus encoding the apoptosis inducer, TRAIL.

Jiménez JA, Li X, Zhang YP, Bae KH, Mohammadi Y, Pandya P, Kao C, Gardner TA - Cancer Gene Ther. (2009)

Ad-IU2 suppressed the growth of androgen-independent human prostate tumors in athymic mice. A, subcutaneous androgen-independent CWR22rv xenografts were established in castrated male athymic mice and treated with intratumoral injections of PBS (vehicle control, n = 5), Ad-IU1 (PSRCA control, n = 6) or Ad-IU2 (n = 9). Mean tumor volumes at day 0 and study endpoints are listed. *** = p<0.001 (Ad-IU2 vs. Ad-IU1). B, fold tumor growths for individual mice at the 6-week end-point. Histological appearance of harvested tumors 6 weeks after treatment with PBS (C), Ad-IU1 (D) (large yellow arrows, necrotic centers of oncolysis; small yellow arrows, patches of healthy tumor cells) or Ad-IU2 (E) (large yellow arrows, necrotic centers of oncolysis; small yellow arrows, condensed nuclei) (200× magnification). In situ TUNEL assay detected no apoptosis in tumors treated with PBS (F) or Ad-IU1 (G) and marked apoptosis in tumors treated with Ad-IU2 (H).
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Figure 5: Ad-IU2 suppressed the growth of androgen-independent human prostate tumors in athymic mice. A, subcutaneous androgen-independent CWR22rv xenografts were established in castrated male athymic mice and treated with intratumoral injections of PBS (vehicle control, n = 5), Ad-IU1 (PSRCA control, n = 6) or Ad-IU2 (n = 9). Mean tumor volumes at day 0 and study endpoints are listed. *** = p<0.001 (Ad-IU2 vs. Ad-IU1). B, fold tumor growths for individual mice at the 6-week end-point. Histological appearance of harvested tumors 6 weeks after treatment with PBS (C), Ad-IU1 (D) (large yellow arrows, necrotic centers of oncolysis; small yellow arrows, patches of healthy tumor cells) or Ad-IU2 (E) (large yellow arrows, necrotic centers of oncolysis; small yellow arrows, condensed nuclei) (200× magnification). In situ TUNEL assay detected no apoptosis in tumors treated with PBS (F) or Ad-IU1 (G) and marked apoptosis in tumors treated with Ad-IU2 (H).
Mentions: Previously, we investigated the oncolytic potential of Ad-E4PSESE1a, a PSRCA, which significantly inhibited the growth of CWR22rv xenografts as compared to control virus; however, the response only lasted two weeks, after which the tumor growth exceeded the rate of oncolysis. Rapid intratumoral viral replication and spread peaked at 3 days and was diminished by 1 week after injection.36 For this reason, we determined whether TRAIL could augment the in vivo antitumor effects of a PSRCA. Androgen-independent CWR22rv human prostate cancer xenografts were established SQ in the flanks of castrated athymic male mice and injected with Ad-IU2, Ad-IU1 (replication-competent control) and PBS (vehicle control). Ad-IU2 significantly suppressed the growth of CWR22rv tumor xenografts as compared to Ad-IU1 (3.1-vs. 17.1-fold growth of tumor, respectively). 4 weeks after treatment, Ad-IU1-treated tumors began to fail therapy, resulting in a rebound of tumor growth. On the other hand, Ad-IU2 continued to inhibit tumor growth through the 6-week end-point of the study. Mock-treated mice were sacrificed at 5 weeks due to overwhelming tumor burden (Figure 5A). Of the nine tumors treated with Ad-IU2, six responded favorably with partial regression in four of six or complete regression in two of six tumors. Of the three tumors that failed, two were significantly suppressed compared to Ad-IU1 tumors at 6-weeks (Figure 5B). Given the fact that CWR22rv xenografts are clonogenic, the variation in treatment outcome may be attributed to incomplete tumor infiltration or leakage of virus at the time of injection. Histological examination of PBS-treated tumors revealed healthy cells arranged in normal tumor architecture with significant tumor vasculature in the margins of the growing tumor (Figure 5C). Ad-IU1-treated tumors were characterized by scattered necrotic patches surrounded by healthy tumor cells, indicative of incomplete oncolysis due to limited viral replication and propagation throughout the entire tumor mass (Figure 5D). Although patches of healthy tumor cells remained within the Ad-IU2-treated tumors, necrotic centers of viral replication and oncolysis were more diffuse throughout the entire tumor. Furthermore, cells immediately surrounding the necrotic centers appeared unhealthy with condensed nuclei, indicating spread of the cytotoxic and apoptotic effect beyond the necrotic centers (Figure 5E). To determine whether apoptosis contributed significantly to the tumor killing process, in situ TUNEL assays were performed on the tumor sections. No apoptotic nuclei were detected in the control tumors (Figure 5F-G). On the other hand, Ad-IU2-treated tumors displayed marked apoptosis in the margins surrounding necrotic centers of oncolysis (Figure 5H). These data suggest that TRAIL potentiated the in vivo killing power of a PSRCA through apoptosis induction in cells beyond the margin of viral replication.

Bottom Line: Ad-IU2 induced fivefold greater apoptosis selectively in PSA/PSMA-positive CWR22rv and C4-2 cells than an oncolytic adenoviral control.Furthermore, prolonged infection with Ad-IU2 reversed TRAIL resistance in LNCaP cells.This study shows the potential clinical utility of a PSRCA armed with an apoptosis-inducing ligand.

View Article: PubMed Central - PubMed

Affiliation: Department of Urology, Indiana University School of Medicine, Indianapolis, IN, USA.

ABSTRACT
In this study, we analyzed the preclinical utility and antitumor efficacy of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) delivered by Ad-IU2, a prostate-specific replication-competent adenovirus (PSRCA), against androgen-independent prostate cancer. Through transcriptional control of adenoviral early genes E1a, E1b and E4, as well as TRAIL by two bidirectional prostate-specific enhancing sequences (PSES), the expression of TRAIL and adenoviral replication was limited to prostate-specific antigen (PSA) and prostate-specific membrane antigen (PSMA)-positive cells. Ad-IU2 induced fivefold greater apoptosis selectively in PSA/PSMA-positive CWR22rv and C4-2 cells than an oncolytic adenoviral control. Furthermore, prolonged infection with Ad-IU2 reversed TRAIL resistance in LNCaP cells. Ad-IU2 showed superior killing efficiency in PSA/PSMA-positive prostate cancer cells at doses five- to eight-fold lower than required by a PSRCA to produce a similar effect; however, this cytotoxic effect was not observed in non-prostatic cells. As an enhancement of its therapeutic efficacy, Ad-IU2 exerted a TRAIL-mediated bystander effect through direct cell-to-cell contact and soluble factors such as apoptotic bodies. In vivo, Ad-IU2 markedly suppressed the growth of subcutaneous androgen-independent CWR22rv xenografts compared with a PSRCA at 6 weeks after treatment (3.1- vs 17.1-fold growth of tumor). This study shows the potential clinical utility of a PSRCA armed with an apoptosis-inducing ligand.

Show MeSH
Related in: MedlinePlus