Ivan Ding

Pentoxifylline in the Treatment of Radiation-Induced Fibrosis

PURPOSE Fibrotic sequelae remain the most important dose-limiting toxicity of radiation therapy to soft tissue. Functionally, this is reflected in loss of range of motion and muscle strength and the development of limb edema and pain. Tumor necrosis factor alpha and fibroblast growth factor 2 (FGF2), which are abnormally elevated in irradiated tissues, may mediate radiation fibrovascular injury. PATIENTS AND METHODS In an open label drug trial, we studied the effects of pentoxifylline (400 mg orally tid for 8 weeks) on 30 patients who displayed late, radiation-induced fibrosis at 1 to 29 years posttreatment (40 to 84 Gy). The primary outcome measurement was change in physical impairments thought to be secondary to radiation, including active and passive range of motion (AROM and PROM), muscle strength, limb edema, and pain. Plasma levels of cytokines (tumor necrosis factor alpha and FGF2) also were measured. Twenty-seven patients completed baseline and 8-week assessments, and 24 patients completed baseline, 8-week, and 16-week assessments. RESULTS After 8 weeks of pentoxifylline intervention, 20 of 23 patients with impaired AROM and 19 of 22 with impaired PROM improved; 11 of 19 patients with muscle weakness showed improved motor strength; five of seven patients with edema had decreased limb girth; and nine of 20 patients had decreased pain. Pretreatment FGF2 levels dropped from an average of 44.9 pg/mL to 24.0 pg/mL after 8 weeks of treatment. CONCLUSION Patients receiving pentoxifylline demonstrated improved AROM, PROM, and muscle strength and decreased limb edema and pain. Reversal of these delayed radiation effects was associated with a decrease in circulating FGF2.

In Vivo Radioprotective Effects of Angiogenic Growth Factors on the Small Bowel of C3H Mice

This study was undertaken to determine if acidic or basic fibroblast growth factor (FGF1 or FGF2) or vascular endothelial growth factor (VEGF) alters the radiation response of small bowel after total-body irradiation (TBI). Female C3H mice were treated with various doses of angiogenic growth factor administered intravenously 24 h before or 1 h after TBI. Radiation doses ranged from 7 to 18 Gy. End points measured were the number of crypts in three portions of the small bowel, the frequency of apoptosis of crypt cells at various times after TBI, and the LD50/30 (bone marrow syndrome) and LD50/6 (GI syndrome). Fibroblast growth factors alone, without TBI, decreased the number of crypts per circumference significantly. Among the factors tested, FGF2 caused the greatest decline in baseline crypt number. Despite this decrease in the baseline crypt number, after irradiation the number of surviving crypts was greater in animals treated with growth factor. The greatest radioprotection occurred at intermediate doses of growth factor (6 to 18 pg/mouse). Mice treated with FGF1 and FGF2 had crypt survival curves with a slope that was more shallow than that for saline-treated animals, indicating radiation resistance of crypt stem cells in FGF-treated mice. The LD50/6 was increased by approximately 10% for all treatments with angiogenic growth factors, whether given before or after TBI. Apoptosis of crypt cells was maximum at 4 to 8 h after TBI. The cumulative apoptosis was decreased significantly in animals treated with angiogenic growth factors, and the greatest protection against apoptosis was seen in animals treated with FGF2 prior to TBI. All three angiogenic growth factors tested were radioprotective in small bowel whether given 24 h before or 1 h after irradiation. The mechanism of protection is unlikely to involve proliferation of crypt stem cells, but probably does involve prevention of radiation-induced apoptosis or enhanced repair of DNA damage of crypt cells.

MCF-7 breast carcinoma cells overexpressing FGF-1 form vascularized, metastatic tumors in ovariectomized or tamoxifen-treated nude mice

FGF-1 is expressed in a high proportion of breast tumors. While overexpression of FGF-4 in the MCF-7 breast carcinoma cell line confers the ability to form spontaneously metastasizing tumors in ovariectomized nude mice without estrogen supplementation and in mice that receive tamoxifen pellets, the response of a cell to individual FGFs can be controlled at multiple levels, and the significance of FGF-1 expression in human breast tumors is uncertain. To study the role of FGF-1, MCF-7 human breast cancer carcinoma cells, previously transfected with bacterial β-galactosidase, were retransfected with FGF-1 expression vectors. FGF-1 transfectants formed large, vascularized tumors in ovariectomized nude mice without estrogen supplementation as well as in mice that received tamoxifen pellets. Lymphatic and pulmonary micrometastases were detected as deposits of X-gal-stained cells as early as 17 days after cell inoculation whereas no metastases were detected in estrogen-supplemented mice bearing similar-sized control tumors. When compared with controls, both clonal and polyclonal populations of FGF-1 overexpressing cells exhibited increased anchorage-independent growth and decreased population doubling times in estrogen-depleted or 4-hydroxytamoxifen containing medium. These results suggest that FGF signaling may be important in the transition of breast cancer cells from hormone-dependent to hormone-independent and from nonmetastatic to metastatic.

Interleukin 1β (IL1B) signaling is a critical component of radiation-induced skin fibrosis

Abstract Liu, W., Ding, I., Chen, K., Olschowka, J., Xu, J., Hu, D., Morrow, G. and Okunieff, P. Interleukin 1β (IL1B) Signaling is a Critical Component of Radiation-Induced Skin Fibrosis. Radiat. Res. 165, 181–191 (2006). Interleukin 1 beta (IL1B), a potent pro-inflammatory cytokine, is directly up-regulated by radiation and is known to regulate other inflammation-related molecules, such as the matrix metalloproteinases (MMPs) and their endogenous inhibitors (TIMPs). However, the nature of the interaction of IL1B with MMPs and TIMPs in radiation-induced skin fibrosis is unknown. We examined the response of primary dermal keratinocytes, fibroblasts and endothelial cells to single-fraction radiation (10 Gy) and compared the results to a temporal sequence of histology from irradiated C57BL/6 and IL1R1 knockout mice. These studies showed that keratinocytes are the major IL1-producing cells in vitro and that radiation induces an immediate and chronic elevation in the expression of IL1B mRNA in the skin of C57BL/6 mice. This elevation was principally early and was less pronounced in the IL1R1 knockout strain, which also demonstrated reduced late radiation fibrosis. Radiation also increased expression of MMP mRNA in C57BL/6 mice. Finally, exogenous IL1B protein induced robust endogenous IL1B mRNA expression, along with a brisk increase in MMPs and collagen III, but only in the C57BL/6 mice. In conclusion, these data suggest that IL1B plays a critical role in radiation-induced fibrosis and that the increased MMPs fail to block the IL1-related collagen accumulation.

Celecoxib reduces skin damage after radiation: selective reduction of chemokine and receptor mRNA expression in irradiated skin but not in irradiated mammary tumor.

Inflammatory cytokine and chemokine production is mediated, at least in part, by prostaglandin E (PGE2). Cyclooxygenases, COX-1 and COX-2, are two key enzymes in the conversion of arachidonic acid to PGE2. Radiation induces the overproduction of cytokines and chemokines, and it also increases PGE2 production, both locally and systemically. In this study, we tested the effects of a COX-2 inhibitor (celecoxib) after 50 Gy radiation of MCa-35 tumor and cutaneous tissues of C3H/He mice. Preclinical toxicity endpoints and associated alterations in chemokine production and cellular infiltrates were measured. Celecoxib was given by daily gavage (50 mg/kg for 15 days), with the first dose delivered either 2 hours before, 2 days after, or 7 days after a single dose of radiation. Celecoxib-treated animals had less inflammation of the dermis compared with saline-treated controls. Severe skin dermatitis occurred in 23.8% (5/21) of mice treated with 50 Gy, whereas only 17.6%, 5.3%, and 11.1% of mice in the 2-hour pre-, or the 2-day post-, and 7-day postirradiation groups, respectively, had severe dermatitis on day 20. The decreased skin toxicity scores were associated with a reduction of both blood vessels and focal necrosis in MCa-35 tumors. Celecoxib also significantly decreased C-C family chemokine (Rantes and MCP-1) mRNA expression in irradiated skin tissues, but not in tumor tissues, which was accompanied by a decrease in skin mRNA expression of both C-C (CCR2 and CCR5) and C-X-C (CXCR2 and CXCR4) chemokine receptors. A significant positive correlation was also found between skin damage (skin scores) and chemokine and its receptor mRNA expression in radiation-treated mice. Finally, celecoxib also decreased the infiltration of monocytes and neutrophils in locally irradiated tumor and surrounding normal tissue. The differential effects of celecoxib on inflammation help to explain the selective protection by celecoxib of irradiated cutaneous tissues without a concurrent protection of MCa-35 tumors.

Reduced hGC-1 Protein Expression Is Associated with Malignant Progression of Colon Carcinoma

Purpose: hGC-1 (human granulocyte colony–stimulating factor–stimulated clone 1) is a gastrointestinal protein that is a member of the olfactomedin glycoprotein family. Its biological function remains poorly understood. Aberrant expression of hGC-1 in some human carcinomas has been recently reported. The purpose of this study was to examine hGC-1 expression in colon carcinoma and explore the relationship between hGC-1 expression and the clinicopathologic features of patients with colon cancer. Experimental Design: The expression of hGC-1 in colon adenocarcinoma tissues was examined by dot-blot analysis, in situ hybridization, and immunohistochemistry. The association of hGC-1 expression pattern with patient differentiation grade, tumor stage, metastasis, and survival were examined. To further investigate the involvement of hGC-1 in colon cancer progression, human colon carcinoma (HT-29) cells overexpressing hGC-1 were established and cell proliferation, adhesion, and migration were studied. Results: Compared with normal colon mucosa, the up-regulation of hGC-1 was more frequently detected in more differentiated colon cancers, whereas down-regulation or no expression was associated with poorly differentiated colon cancers. Interestingly, hGC-1 down-regulation was also found in late tumor-node-metastasis stage, metastasis, and in patients with shorter survival. The morphology and cortical actin distribution of HT-29 cells were altered by hGC-1 overexpression. However, this did not change cell proliferation, but decreased cell adhesion and migration. Conclusion: Our findings indicate that hGC-1 is involved in colon cancer adhesion and metastasis, and that hGC-1 may be a useful marker for tumor differentiation and progression of human colon carcinoma.

Combination of radiation and celebrex (celecoxib) reduce mammary and lung tumor growth.

The selective cyclooxygenase (COX)-2 inhibitor, celecoxib, alone and in combination with radiation was investigated in vitro and in vivo. Murine mammary tumor line (MCa-35) and human lung carcinoma line (A549) have high and low basal levels of COX-2 protein, respectively. Treatment of both tumor cells with celecoxib alone resulted in a dose- and time-dependent reduction of cell number (clonogenic cell death) and tumor cell growth rate in vitro; however, inhibition of tumor cell growth by celecoxib was not correlated with the reduction of COX-2 protein in tumor cells. Although both tumor cell types had similar DNA damage after celecoxib treatment, significant induction of tumor cell apoptosis was only observed in MCa-35. Celecoxib-mediated radiation sensitization also occurred in MCa-35 cells determined by clonogenic assay, in part due to a G2/M arrest at 8 to 24 hours after treatment. The tumor growth inhibitory effects of celecoxib were also studied in vivo. It was found that celecoxib inhibited both tumor growth after intragastric administration of celecoxib (5 daily doses of 50 mg/kg). Combined with a single 30-Gy dose of radiation, celecoxib resulted in additive effects on A549 tumors. Celecoxib-treated A549 tumors had marginal reduction of total and perfused blood vessels compared with untreated controls. Reduction of tumor angiogenic cytokine and growth factor mRNA was associated with decreased perfused vessels. Finally, reduction of vascular endothelial growth factor protein after celecoxib was also observed in both tumor lines by Western blot. Our results indicate that the selective inhibition of COX-2 combined with radiation has potential application in radiotherapy, and celecoxib-mediated antitumor effects may act through different mechanisms including direct inhibition of tumor cell proliferation, alteration of tumor cell cycle, and antiangiogenesis.

Keratinocyte growth factors radioprotect bowel and bone marrow but not KHT sarcoma

Various members of the fibroblast growth factor (FGF) family of proteins have been shown to protect against acute and late radiation damage of normal tissues. Protection of the small bowel, for example, occurs via both increased proliferation and reduced apoptosis. Other beneficial effects of FGFs include promotion of bone growth, pneumonitis prevention, and apoptosis suppression of endothelium in vivo and in vitro after irradiation. This protection against radiation requires only low and infrequent doses of FGFs. Two newly identified members of the FGF family, FGF7 and FGF10, have effects similar to many of the other FGF family proteins, but with more specificity for normal epithelial structures. For this reason, they have also been named keratinocyte growth factors one and two (KGF1 and KGF2, respectively). We therefore examined the potential utility of KGFs for radioprotection of the bone marrow and small bowel and examined safety issues concerning their adverse effects on KHT sarcoma. The results suggest that KGFs could be safely used to prevent radiation toxicity of the abdomen or pelvis and may in fact improve tumor response to radiation.

Enhanced Antitumor Effect of Combined Triptolide and Ionizing Radiation

Purpose: The lack of effective treatment for pancreatic cancer results in a very low survival rate. This study explores the enhancement of the therapeutic effect on human pancreatic cancer via the combination of triptolide and ionizing radiation (IR). Experimental Design:In vitro AsPC-1 human pancreatic cancer cells were treated with triptolide alone, IR alone, or triptolide plus IR. Cell proliferation was analyzed with sulforhodamine B (SRB) method and clonogenic survival; comparison of apoptosis induced by the above treatment was analyzed by annexin V–propidium iodide (PI) staining. Furthermore, the expression of apoptotic pathway intermediates was measured by the assay of caspase activity and Western blot. Mitochondrial transmembrane potential was determined by JC-1 assay. In vivo, AsPC-1 xenografts were treated with 0.25 mg/kg triptolide, 10 Gy IR, or triptolide plus IR. The tumors were measured for volume and weight at the end of the experiment. Tumor tissues were tested for terminal nucleotidyl transferase–mediated nick end labeling (TUNEL) and immunohistochemistry. Results: The combination of triptolide plus IR reduced cell survival to 21% and enhanced apoptosis, compared with single treatment. In vivo, tumor growth of AsPC-1 xenografts was reduced further in the group treated with triptolide plus IR compared with single treatment. TUNEL and immunohistochemistry of caspase-3 cleavage in tumor tissues indicated that the combination of triptolide plus IR resulted in significantly enhanced apoptosis compared with single treatments. Conclusions: Triptolide in combination with ionizing radiation produced synergistic antitumor effects on pancreatic cancer both in vitro and in vivo and seems promising in the combined modality therapy of pancreatic cancer.

Olfactomedin 4 suppresses prostate cancer cell growth and metastasis via negative interaction with cathepsin D and SDF-1

The human olfactomedin 4 gene (OLFM4) encodes an olfactomedin-related glycoprotein. OLFM4 is normally expressed in a limited number of tissues, including the prostate, but its biological functions in prostate are largely unknown. In this study, we found that OLFM4 messenger RNA was reduced or undetectable in prostate cancer tissues and prostate cancer cell lines. To study the effects of OLFM4 on prostate cancer progression, we transfected PC-3 prostate cancer cells with OLFM4 to establish OLFM4-expressing PC-3 cell clones. The OLFM4-expressing PC-3 cell clones were found to have decreased proliferation and invasiveness compared with vector-transfected control PC-3 cells in vitro. In addition, nude mice injected with OLFM4-expressing PC-3 cells demonstrated reduced tumor growth and bone invasion and metastasis compared with mice injected with vector-transfected control cells. Mechanistic studies revealed that OLFM4 may exhibit its anticancer effects through regulating cell autophagy by targeting cathepsin D, as OLFM4 reduced cathepsin D protein levels and enzymatic activity and attenuated cathepsin D-induced cancer cell proliferation. In addition, overexpression of OLFM4 abrogated stromal cell derived factor-1 (SDF-1)-induced PC-3 cell invasiveness in a Matrigel invasion assay, partially through blocking SDF-1-mediated AKT phosphorylation. Coimmunoprecipitation and immunofluorescence staining studies in OLFM4-expressing PC-3 cells demonstrated a direct interaction between OLFM4 and cathepsin D or SDF-1. Taken together, these results suggest that OLFM4 negatively interacts with cathepsin D and SDF-1 and inhibits prostate cancer growth and bone metastasis.