Alternative treatment in retinoblastoma

Pinocembrin suppresses TGF-β1-induced epithelial-mesenchymal transition and metastasis of human Y-79 retinoblastoma cells through inactivating αvβ3 integrin/FAK/p38α signaling pathway

Background

Pinocembrin is the most abundant flavonoid in propolis. In this study, we investigated the antimetastatic effect of pinocembrin on TGF-β1-induced epithelial-mesenchymal transition (EMT) and metastasis of human Y-79 retinoblastoma cells.

Results

Firstly, the results showed that pinocembrin significantly suppresses the TGF-β1-induced abilities of the invasion and migration of Y-79 cells under non-cytotoxic concentration. Pinocembrin decreased TGF-β1-induced expression of vimentin, N-cadherin, αv and β3 integrin in Y-79 cells. Molecular data also showed pinocembrin inhibits the activation of focal adhesion kinase (FAK) and p38α signal involved in the downregulation of enzyme activities, protein and messenger RNA levels of matrix metalloproteinase-2/9 (MMP-2/-9) induced by TGF-β1. Next, pinocembrin also strongly inhibited the degradation of inhibitor of kappaBα (IκBα) and the nuclear levels of nuclear factor kappa B (NF-κB). Also, a dose-dependent inhibition on the binding ability of NF-κB was further observed under pinocembrin treatment.

Conclusions

Presented results indicated that pinocembrin inhibits TGF-β1-induced epithelial-mesenchymal transition (EMT) and metastasis of Y-79 cells by inactivating the αvβ3 integrin/FAK/p38α signaling pathway. Thus, our findings point to the anticancer potential of pinocembrin against retinoblastoma cells.

Toxicity and dose-response studies of 1-alpha hydroxyvitamin D2 in LH-beta-tag transgenic mice

PURPOSE

To determine the effectiveness of a vitamin D analog, 1alpha-hydroxyvitamin D(2) (1alpha-OH-D(2)), in inhibiting retinoblastoma in a transgenic retinoblastoma model (LHbeta-Tag mouse) and to evaluate its toxicity.

DESIGN

Experimental study using an animal (LHbeta-Tag transgenic mouse) randomized (controlled) trial.

PARTICIPANTS AND CONTROLS

Two hundred seventeen LHbeta-Tag transgene-positive 8- to 10-week-old mice total; 179 drug-treated animals, 38 control animals.

METHODS

Mice were fed a vitamin D- and calcium-restricted diet and were randomized to treatment groups receiving control (vehicle), or 0.1, 0.3, 0.5, or 1.0 micro g/day of 1alpha-OH-D(2) via oral gavage 5 times weekly for 5 weeks. Body weight was measured at the start of treatment and twice weekly during treatment. Animals were euthanized on the last day of treatment. The eyes were enucleated, processed histologically, and serially sectioned. Representative sections from the superior, middle, and inferior regions of each globe were examined microscopically and tumor areas were measured using Optimas software. Serum was collected for serum calcium levels. Kidneys were removed for histologic processing and were analyzed microscopically for kidney calcification.

MAIN OUTCOME MEASURES

Mean tumor area was measured to determine drug effectiveness. Toxicity was assessed by survival, weight loss over the treatment period, serum calcium, and kidney calcification.

RESULTS

The mean tumor size in each 1alpha-OH-D(2) group was smaller than controls (all P values < 0.02): control, 90,248 micro m(2); 0.1 micro g, 31,545 micro m(2); 0.3 micro g, 16,750 micro m(2); 0.5 micro g, 30,245 micro m(2); and 1.0 micro g, 16,049 micro m(2). No dose-dependent response curve was evident. The survival percentage for each group was as follows: control, 97%; 0.1 micro g, 91%; 0.3 micro g, 88%; 0.5 micro g, 70%; and 1.0 micro g, 63%. Mortality was higher in the 0.5- micro g and 1.0- micro g doses (P values < 0.01) compared with other treatment groups and with the control group. Serum calcium levels were significant in all treatment groups compared with controls (all P values < 0.0001).

CONCLUSIONS

In the LHbeta-Tag mouse, 1alpha-OH-D(2) inhibits retinoblastoma with no significant increase in mortality in lower doses (0.1-0.3 micro g). 1alpha-OH-D(2) has approval by the Food and Drug Administration as an investigative drug for cancer treatment, and has shown efficacy with low toxicity in adult cancer trials. 1alpha-OH-D(2) meets the criteria for human clinical trials.

Vitamin D analogs, a new treatment for retinoblastoma: The first Ellsworth Lecture

PURPOSE

This lecture honors the memory of Dr. Robert M. Ellsworth, an important figure in the development of current treatments of retinoblastoma (RB), and reviews our studies of vitamin D analogs as treatments for retinoblastoma in two experimental mouse models. We identified vitamin D receptors in retinoblastoma and examined the effectiveness and mechanism of action of these analogs.

METHODS

Reverse-transcriptase polymerase chain reaction (RT-PCR) amplification was used to detect vitamin D receptor mRNAs in human and mouse retinoblastomas. The effectiveness and toxicity of vitamin D(2), calcitriol, and synthetic analogs were studied in the athymic/Y-79 xenograft and transgenic mouse models of RB. Dosing was 5X/week for five weeks. Dose-response studies focused on tumor inhibition; toxicity studies investigated survival and serum calcium. The mechanism of action of vitamin D was investigated using terminal transferase dUTP labeling 3'-overhang ligation to measure apoptosis; immunohistochemistry measured p53-dependent gene expression and cell proliferation.

RESULT

Vitamin D receptor mRNAs were detectable in Y-79 RB cells, LH beta-Tag tumors, and human RB specimens using RT-PCR. Calcitriol inhibited cell growth in vitro. Calcitriol and vitamin D(2) inhibited in vivo growth in xenograft and transgenic models, but therapeutic levels were toxic due to hypercalcemia. Two analogs, 16,23-D(3) and 1 alpha-OH-D( 2), inhibited tumors in animal models of RB with reduced toxicity. The mechanism of action appears related to increased p53-related gene expression resulting in increased apoptosis.

CONCLUSION

16,23-D(3) and 1 alpha-OH-D(2) are effective in tumor reduction in two mouse models of RB with low toxicity. These results warrant initiating phase 1 and phase 2 clinical studies in children.

Chemoreduction plus focal therapy for retinoblastoma: factors predictive of need for treatment with external beam radiotherapy or enucleation

PURPOSE

To report the results of chemoreduction and focal therapy for retinoblastoma with determination of factors predictive of the need for treatment with external beam radiotherapy or enucleation.

DESIGN

Interventional case series.

METHODS

One-hundred three patients with retinoblastoma (158 eyes with 364 tumors) at the Ocular Oncology Service at Wills Eye Hospital of Thomas Jefferson University in conjunction with the Division of Oncology at Children's Hospital of Philadelphia from June 1994 to August 1999 were enrolled for this prospective clinical trial. The patients received treatment for retinoblastoma with six planned cycles (one cycle per month) of chemoreduction using vincristine, etoposide, and carboplatin combined with focal treatments (cryotherapy, thermotherapy, or plaque radiotherapy). The two main outcome measures after chemoreduction and focal therapy were the need for external beam radiotherapy and the need for enucleation. The clinical features at the time of patient presentation were analyzed for impact on the main outcome measures using a series of Cox proportional hazards regressions.

RESULTS

Using Reese-Ellsworth (RE) staging for retinoblastoma, there were nine (6%) eyes with group I disease, 26 (16%) eyes with group II disease, 16 (10%) eyes with group III disease, 32 (20%) eyes with group IV disease, and 75 (48%) eyes with group V retinoblastoma. All eyes showed initial favorable response with tumor regression. The median follow-up was 28 months (range, 2-63 months). Failure of chemoreduction and need for treatment with external beam radiotherapy occurred in 25% of eyes at 1 year, 27% at 3 years, and no further increase at 5 years. More specifically, external beam radiotherapy was necessary at 5 years in 10% of RE groups I-IV eyes and 47% of RE group V eyes. Multivariate factors predictive of treatment with external beam radiotherapy included non-Caucasian race, male sex, and RE group V disease. Failure of chemoreduction and the need for treatment with enucleation occurred in 13% eyes at 1 year, 29% at 3 years, and 34% at 5 years. More specifically, enucleation was necessary in 15% of RE groups I-IV eyes at 5 years and in 53% of RE group V at 5 years. Multivariate factors predictive of treatment with enucleation included patient age older than 12 months, single tumor in eye, and tumor proximity to foveola within 2 mm. Overall, of the 158 eyes, 50% required external beam radiotherapy or enucleation and 50% were successfully managed without these treatments. No patient developed retinoblastoma metastasis, pinealoblastoma, or second malignant neoplasms over the 5-year follow up.

CONCLUSIONS

Chemoreduction offers satisfactory retinoblastoma control for RE groups I-IV eyes, with treatment failure necessitating additional external beam radiotherapy in only 10% of eyes and enucleation in 15% of eyes at 5-year follow-up. Patients with RE group V eyes require external beam radiotherapy in 47% and enucleation in 53% at 5 years.