Continuous and low-energy 125I seed irradiation changes DNA methyltransferases expression patterns and inhibits pancreatic cancer tumor growth

Mechanistic insights into 125I seed implantation therapy for Cholangiocarcinoma: focus on ROS-Mediated apoptosis and the role of GPX2

OBJECTIVES

Cholangiocarcinoma (CCA) is a rare tumor with a poor prognosis and poses significant therapeutic challenges. Herein, we investigated the mechanism of efficacy of 125I seed implantation therapy in CCA, focusing on the induction of reactive oxygen species (ROS)-mediated apoptosis and the involvement of glutathione peroxidase 2 (GPX2).

MATERIALS AND METHODS

Human cholangiocarcinoma cell lines QBC939 and RBE were purchased for in vitro studies. In vivo studies were performed using a rabbit VX2 CCA model. Apoptosis and proliferation were detected by TUNEL staining and clone formation, respectively. ROS generation was detected by dihydroethidium staining. Histological evaluation was performed by hematoxylin and eosin staining. Protein expression was determined by Western blotting and immunohistochemistry.

RESULTS

Our results demonstrate that 125I seeds effectively inhibited tumor growth in the rabbit VX2 tumor model and promoted the apoptosis of CCA cells in vitro in a dose-dependent manner. Molecular analyses indicate a marked increase in reactive oxygen species (ROS) levels following treatment with 125I seeds, suggesting the involvement of ROS-mediated apoptosis in the therapeutic mechanism. Furthermore, the downregulation of glutathione peroxidase 2 (GPX2) was observed, indicating its potential role in modulating ROS-mediated apoptosis in CCA.

CONCLUSION

125I seed implantation therapy exerts therapeutic effects on CCA by inducing ROS-mediated apoptosis. The downregulation of GPX2 may contribute to enhanced ROS accumulation and apoptotic cell death. These findings provide mechanistic insights into the therapeutic potential of 125I seed implantation for CCA and highlight ROS-mediated apoptosis and GPX2 regulation as promising targets for further investigation and therapeutic intervention in this malignancy.

[MiR-132-3p negatively regulates CAMTA1 to promote Schwann cell proliferation and migration and alleviates I-125 seeds-induced exacerbation of facial nerve injury in rats]

OBJECTIVE

To investigate the regulatory effect of miR-132-3p on calmodulin-binding transcription activator 1 (CAMTA1) and Schwann cell activity in rats with facial nerve injury (FNI) treated with I-125 seeds.

METHODS

Rat Schwann cells were irradiated with I-125 seeds and transfected with miR-132-3p mimic, miR-132-3p inhibitor or sh-CAMTA1. The expressions of S100B and β-tubulin Ⅲ in the cells were detected with immunofluorescence assay, and the expressions of miR-132-3p and CAMTA1 protein were determined using RT-qPCR and Western blotting, respectively. EdU staining and Transwell assay were used to evaluate the changes in cell proliferation and migration ability. In a rat model of FNI, I-125 seeds were implanted into the facial tissues near the facial nerve 2 weeks before modeling, and miR-132-3p mimic was injected subcutaneously in the face after modeling. The pathologies of the facial nerve was assessed by HE, LFB and immunofluorescence staining. The targeting relationship between miR-132-3p and CAMTA1 was verified using StarBase v2.0 database and dual-luciferase reporter assay.

RESULTS

Rat Schwann cells showed high expressions of S100B and β-tubulin Ⅲ. I-125 seeds radiation significantly decreased miR-132-3p expression and repressed proliferation and migration of the cells (P < 0.001). Overexpression of miR-132-3p or CAMTA1 knockdown obviously enhanced proliferation and migration of the Schwann cells, while miR-132-3p knockdown produced the opposite effect. MiR-132-3p negatively regulated CAMTA1 expression. In the rat models of FNI, miR-132-3p injection significantly inhibited CAMTA1 expression and attenuated I-125 seeds-induced exacerbation of FNI.

CONCLUSION

Overexpression of miR-132-3p suppresses CAMTA1 expression and promotes Schwann cell proliferation and migration to alleviate I-125 seeds-induced exacerbation of FNI in rats.

AMIGO2 is a pivotal therapeutic target related to M2 polarization of macrophages in pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is a common kind of lethal cancer, with low early diagnostic rate and poor prognosis. In this study, we identified and verified the AMIGO2 with significant diagnostic and prognostic value in PDAC through LASSO regression combined with multiple machines learning methods, including RVM-RFE and Random Forest in TCGA and GEO datasets. The relevance between the expression of AMIGO2 and M2 polarization of macrophages was identified through pancancer, normal tissue, and cell lines data in TCGA, GTEx and CCLE datasets. The relevance between AMIGO2 and M2 polarization was then further identified in our local PDAC cohort. Finally, the role of AMIGO2 as cancer promoter and pivotal factor enrolled in M2 polarization was verified through siRNA transfection and M2 macrophages induction. These findings could facilitate diagnosis and treatment of PDAC. In addition, further research was deemed necessary on the deep mechanism between AMIGO2 and M2 polarization of macrophages in PDAC.

Iodine-125 seed implantation in the treatment of malignant tumors

Malignant tumors are major causes of morbidity and mortality in China. Despite advances in surgical, radiological, chemotherapeutic, molecular targeting, and immunotherapeutic treatments, patients with malignant tumors still have poor prognoses. Low-dose-rate brachytherapy, specifically 125I seed implantation, is beneficial because of its high local delivery dose and minimal damage to surrounding tissues. Consequently, it has gained increasing acceptance as a treatment modality for various malignant tumors. In this study, we explored the fundamental principles, clinical applications, and new technologies associated with 125I radioactive seed implantation.

Celiac plexus block combined with 125I seeds for refractory epigastric pain from abdominal malignancies: a retrospective case-control study

PURPOSE

To evaluate the clinical efficacy of celiac plexus block (CPB) combined with ¹²⁵I seeds implantation (ISI) for refractory epigastric pain from abdominal malignancies.

METHODS

The data of 81 patients with refractory epigastric pain [visual analog scale (VAS) score ≥ 4] from abdominal malignancies were collected in this retrospective case-control study. Group A (n = 40) was treated with CPB alone, while Group B (n = 41) underwent CPB combined with ISI. The primary study endpoints were the VAS score, quality of life (QoL), and local tumor control (LTC) rate. The secondary endpoints were complications, progression-free survival (PFS), and overall survival (OS).

RESULTS

The VAS scores at week 2 (T2), week 4 (T4), week 8 (T8), and week 12 (T12) in both groups were significantly lower compared with the pretreatment values (all P < 0.01). VAS scores in Group B showed a sustained decrease, especially for "mild pain" and "moderate pain," while the VAS scores in Group A rebounded at T8 and T12 (both P < 0.01). The QoL in Group B improved significantly from T4 until T12, which better than that at T12 in Group A (all P < 0.01). The LTC rates at T8 were 35.0% and 92.7% in Groups A and B, respectively, with a significant difference (P < 0.01). Group B had a slightly lower complication rate and a slightly longer median PFS/OS than group A, but neither was statistically different (P = 0.09 and P = 0.99, respectively).

CONCLUSION

CPB combined with ISI performs more sustained pain relief (up to 12 weeks) compared to CPB alone, and ultimately improves the patients' QoL.

Administration of Iodine-125 Seeds Promotes Apoptosis in Cholangiocarcinoma through the PI3K/Akt Pathway

Purpose. We aimed to examine the effects of 125I seeds on the gene expression of Bcl-2, Bax, and PI3K/Akt pathway components in cholangiocarcinoma cells. Methods. In vitro, human cholangiocarcinoma RBE cells were treated with 125I seeds (0.39 mCi or 0.85 mCi) for 72 h, 120 h, and 168 h. Cell proliferation and apoptosis were assessed. The expression of Bcl-2 and Bax was detected by RT-PCR, and Western blotting was carried out to explore changes in Akt activity. Result. 125I seeds inhibited the proliferation of RBE cells. The apoptosis rate of the RBE cells in the low-activity group was significantly higher than that in the high-activity group at 120 h and 168 h, while no difference was found between the two groups at 72 h. After 120 h of culture, the gene expression of Bcl-2 and Bax decreased in both groups, the ratio of $\text{Bcl}-2/\text{Bax}$ in the low-activity group decreased, and the PI3K/Akt signaling pathway was inhibited in both groups. Conclusion. 125I seeds affect the proliferation and apoptosis of cholangiocarcinoma cells in a dose-dependent manner. The therapeutic effect of low-activity 125I seeds on cancer cells may be better. 125I seed brachytherapy may promote the apoptosis of cholangiocarcinoma cells by inhibiting the PI3K/Akt signaling pathway and regulating the $\text{Bcl}-2/\text{Bax}$ ratio.

Iodine-125 seed represses the growth and facilitates the apoptosis of colorectal cancer cells by suppressing the methylation of miR-615 promoter

BACKGROUND

Colorectal cancer (CRC) represents a common malignancy in gastrointestinal tract. Iodine-125 (¹²⁵I) seed implantation is an emerging treatment technology for unresectable tumors. This study investigated the mechanism of ¹²⁵I seed in the function of CRC cells.

METHODS

The CRC cells were irradiated with different doses of ¹²⁵I seed (0.4, 0.6 and 0.8 mCi). miR-615 expression in CRC tissues and adjacent tissues was detected by RT-qPCR. miR-615 expression was intervened with miR-615 mimic or miR-615 inhibitor, and then the CRC cells were treated with 5-AZA (methylation inhibitor). The CRC cell growth, invasion and apoptosis were measured. The methylation level of miR-615 promoter region was detected. The xenograft tumor model irradiated by ¹²⁵I seed was established in nude mice. The methylation of miR-615, Ki67 expression and CRC cell apoptosis were detected.

RESULTS

¹²⁵I seed irradiation repressed the growth and facilitated apoptosis of CRC cells in a dose-dependent manner. Compared with adjacent tissues, miR-615 expression in CRC tissues was downregulated and miR-615 was poorly expressed in CRC cells. Overexpression of miR-615 suppressed the growth of CRC cells. ¹²⁵I seed-irradiated CRC cells showed increased miR-615 expression, reduced growth rate and enhanced apoptosis. The methylation level of miR-615 promoter region in CRC cells was decreased after ¹²⁵I seed treatment. In vivo experiments confirmed that ¹²⁵I seed-irradiated xenograft tumors showed reduced methylation of the miR-615 promoter and increased miR-615 expression, as well as decreased Ki67 expression and enhanced apoptosis. The target genes of miR-615 and its regulatory downstream pathway were further predicted by bioinformatics analysis.

CONCLUSIONS

¹²⁵I seed repressed the growth and facilitated the apoptosis of CRC cells by suppressing the methylation of the miR-615 promoter and thus activating miR-615 expression. The possible mechanism was that miR-615-5p targeted MAPK13, thus affecting the MAPK pathway and the progression of CRC.

125I seeds inhibit proliferation and promote apoptosis in cholangiocarcinoma cells by regulating the AGR2-mediated p38 MAPK pathway

¹²⁵I seeds can effectively inhibit the growth of a variety of cancer cells. It has been used in the treatment of a variety of cancers, and has achieved certain curative effect. However, to the best of our knowledge, no report has described the effects of ¹²⁵I seeds on the biological functions of cholangiocarcinoma (CCA) and the mechanisms underlying the effects of the seeds on this cancer. In this study, we demonstrated that ¹²⁵I seeds could inhibit the proliferation, migration and invasion of CCA cells, as well as promoting apoptosis and blocking the cell cycle in these cells. Moreover, ¹²⁵I seeds inhibited the growth of CCA xenografts and promoted the apoptosis of CCA cells in vivo. Furthermore, transcriptome sequencing showed that ¹²⁵I seeds could inhibit the growth of CCA by inhibiting the expression of AGR2 and regulating p38 MAPK pathway. Finally, this finding indicated that ¹²⁵I seeds can inhibit proliferation and promote apoptosis in CCA cells by inhibiting the expression of AGR2 and DUSP1 and increasing the expression of p-p38 MAPK and p-p53. This study provides a new research direction for studies investigating the mechanisms underlying the effects of ¹²⁵I seeds on CCA.

Development of a Novel Endovascular Brachytherapy Stent: A Proof-of-concept Study

BACKGROUND AND AIMS

Endovascular implantation of iodine-125 (¹²⁵I) seeds strand combined with stent is an effective method of treatment for portal vein tumor thrombosis. The aim of this study was to develop a novel endovascular brachytherapy stent (EVB-Stent) and to evaluate its feasibility of use.

METHODS

An EVB-Stent was implanted into the main portal vein (MPV) in a live porcine model via the percutaneous transhepatic route. Blood samples were collected and tested before and after operation, as well as before euthanasia. Single-photon emission computed tomography (SPECT) combined with CT (SPECT/CT) scan were performed directly after operation and CT scan was performed 2 months after implantation. After the CT scan was performed, all animals were euthanized and histologically examined.

RESULTS

The novel stent was successfully positioned in all six pigs. No deterioration of liver function was observed during the 2-month follow-up period. SPECT/CT revealed the uniform distribution of radiation around the seeds strand, and the hottest spot was near the center of the MPV. The patency of the stented MPV was confirmed using CT scans. The tissue-accumulated absorbed dose was 31,822.11 mGy at 10 mm transversely away from the midpoint of the ¹²⁵I seeds strand, with a half-life of 59.4 days. Pathological examination results showed no significant atrophy or inflammation of adjunct liver tissue, and no obvious intima thickening or thrombosis were detected in the stented MPV.

CONCLUSIONS

A liver porcine model was used to demonstrate that the transhepatic placement of a novel endovascular brachytherapy stent, EVB-Stent, is both technically feasible and safe.

Locally advanced pancreatic carcinoma with jaundice: the benefit of a sequential treatment with stenting followed by CT-guided 125I seeds implantation

OBJECTIVES

To evaluate the role of sequential therapy with percutaneous biliary stenting and CT-guided iodine-125 seed implantation for locally advanced pancreatic carcinoma with concomitant obstructive jaundice.

METHODS

Between January 2016 and December 2018, 42 patients diagnosed with locally advanced pancreatic carcinoma with concomitant obstructive jaundice were enrolled retrospectively. All patients received biliary stenting via percutaneous transhepatic biliary drainage (PTBD) to alleviate obstructive jaundice. Thereafter, twenty-two patients underwent CT-guided iodine-125 seed implantation (treatment group), and 20 did not (control group). The prescribed dose in the treatment group was 110-130 Gy. The clinical data, duration of biliary stent patency, and overall survival (OS) were evaluated.

RESULTS

Overall, the total bilirubin level decreased from 275.89 ± 115.44 to 43.08 ± 43.35 μmol/L (p < 0.001) 1 month after percutaneous biliary stenting. In the treatment group, the postoperative median dose covering 90% of the target volume was 129.71 Gy. Compared with the control group, the treatment group had a long mean duration of biliary stent patency and median OS (11.42 vs. 8.57 months, p < 0.01; 11.67 vs. 9.40 months, p < 0.01, respectively). The overall positive response rates 6 months post-treatment in the treatment and control groups were 72.7% (16/22) and 30% (6/20), respectively. Adverse events of more than grade 3 were not observed during the follow-up.

CONCLUSION

Sequential therapy with percutaneous biliary stenting and CT-guided iodine-125 seed implantation is an effective and safe treatment alternative for locally advanced pancreatic carcinoma with concomitant obstructive jaundice, which is worthy of clinical application.

KEY POINTS

• Obstructive jaundice was alleviated after biliary stent placement in all patients, and the total bilirubin level decreased. • The overall positive response rates at 6 months post-treatment were higher in the treatment group than in the control group, and adverse events of more than grade 3 were not observed during the follow-up period. • Sequential therapy with percutaneous biliary stenting and CT-guided iodine-125 seed implantation can prolong biliary stent patency and improve survival.

125I seeds irradiation inhibits tumor growth and induces apoptosis by Ki-67, P21, survivin, livin and caspase-9 expression in lung carcinoma xenografts

BACKGROUND

Lung cancer is a fatal disease and a serious health problem worldwide. Patients are usually diagnosed at an advanced stage, and the effectiveness of chemotherapy for such patients is very limited. Iodine 125 seed (¹²⁵I) irradiation can be used as an important adjuvant treatment for lung carcinoma. The purpose of this study was to examine the role of irradiation by 125I seeds in human lung cancer xenograft model and to determine the underlying mechanisms involved, with a focus on apoptosis.

METHODS

40 mice with A549 lung adenocarcinoma xenografts were randomly divided into 4 groups: control group (n = 10), sham seed (0 mCi) implant group (n = 10), 125I seed (0.6 mCi) implant group (n = 10) and 125I seed (0.8 mCi) implant group (n = 10), respectively. The body weight and tumor volume, were recorded every 4 days until the end of the study. Apoptotic cells were checked by terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay and activities of caspase-3 and caspase-8 enzyme were tested. Expression of P21, survivin, livin, caspase-9 and proliferating cell nuclear antigen (Ki-67) was detected with immunohistochemical staining.

RESULTS

The results of TUNEL staining assays showed that 125I seed irradiation suppresses the growth of lung cancer xenografts in nude mice and induced apoptosis. The activity of caspase-3 and caspase-8 was significantly higher. The expression levels Ki67, survivin and livin were substantially downregulated, while P21 and caspase-9 protein expression were significantly increased following 125I seed irradiation. This study revealed that 125I seed irradiation could significantly change apoptosis-related protein in human lung cancer xenografts.

CONCLUSIONS

Overall, our study demonstrates that radiation exposure by 125I seeds could be a new treatment option for lung cancer.

A review on the efficacy and safety of iodine-125 seed implantation in unresectable pancreatic cancers

Background: Pancreatic cancers are the common digestive system tumors with poor prognosis and due to its late diagnosis, surgical resection does not remain a viable treatment option in about 80% of patients. Amongst different treatment options, radioactive 125I seed implantation therapy has also emerged as a good alternative in non-resectable pancreatic cancer patients.Purpose: The present review describes the efficacy and safety of iodine-125 seed implantation in unresectable pancreatic cancers in preclinical and clinical studies.Results: In this technique, small radioactive particles are implanted inside the tumor cells to produce the sustain effects. Due to the short radial distance of these radiations, there is a selective and efficient killing of cancer cells without any significant injury to the neighboring cells. Amongst the different methods for implanting 125I seeds in the pancreatic tissues, CT scan or ultrasound-guided percutaneous seed implantation is preferred as it offers shorter operative time, lesser bleeding, early recovery, lesser complications, and low medical costs. The clinical studies have shown that radioactive 125I seed implantation is a good option for the management of local tumor growth, pain palliation, and improvement in the life span of patients suffering from unresectable pancreatic cancer.Conclusion: It may be employed either alone or in combination with cryotherapy, existing chemotherapy, bypass surgery or radiations to achieve the optimal results in these patients. Nevertheless, there is a need to formulate a uniform dose and procedure to achieve homogeneity and develop references for clinical practices.

The role of seed implantation in patients with unresectable pancreatic carcinoma after relief of obstructive jaundice using ERCP

PURPOSE

The purpose of the study was to investigate the role of iodine-125 seed implantation, guided by endoscopic ultrasound (EUS) and/or percutanous ultrasound, in patients with unresectable pancreatic carcinoma after relief of obstructive jaundice using endoscopic retrograde cholangiopancreatography (ERCP).

METHODS AND MATERIALS

A total of 101 patients with obstructive jaundice due to unresectable pancreatic carcinoma were enrolled between January 2010 and December 2017 in this retrospective study. Of these patients, 50 underwent implantation of iodine-125 seeds under EUS and/or percutaneous ultrasound guidance after receiving a stent via ERCP (treatment group), and 51 received a stent via ERCP without undergoing seed implantation (control group). The clinical data and therapeutic outcomes of these patients were analyzed.

RESULTS

Compared with the control group, the treatment group obtained significant relief of abdominal pain at the 1-week, 1-month, and 3-month followup (p < 0.05), with a significantly lower visual analog scale pain score (p < 0.05). The treatment group obtained a longer median survival (8.8 vs. 6.5 months, p = 0.02), longer median duration of stent patency (10.8 ± 1.4 vs. 6.9 ± 0.8 months, p = 0.02), and prolonged average time to gastric outlet obstruction (6.8 ± 1.6 vs. 5.3 ± 1.3 months, p = 0.02). Differences between liver function and appetite for the two groups were not significant (p > 0.05 and p = 0.59, respectively).

CONCLUSIONS

Iodine-125 seed implantation after relief of obstructive jaundice via ERCP prolongs survival, biliary stent patency, and time to gastric outlet obstruction and improves patient quality of life by relieving pancreatic pain in patients with unresectable pancreatic carcinoma.

Percutaneous stenting and chemotherapy for unresectable pancreatic cancer: Comparison of irradiation stents vs conventional metal stents

OBJECTIVES

Percutaneous stenting is a palliative method to relieve obstructive jaundice caused by unresectable pancreatic carcinoma. In this study, we aimed to compare the safety and efficacy of irradiation stents and conventional metal stents.

METHODS

A total of 32 patients who received irradiation stents or conventional metal stents to treat obstructive jaundice caused by locally advanced pancreatic cancer were included in this retrospective study. Chemotherapy using gemcitabine was performed after jaundice subsided. Stent patency, technical success, survival, and complications were compared between groups.

RESULTS

Seventeen patients were enrolled in the irradiation stent group (ISG), and 15 patients were enrolled in the uncovered stent group (USG). Median and mean stent patency time were 9.8 months (95% CI, 7.682-11.981) and 9.506 months (95% CI, 8.0-11.012) in the ISG, respectively, vs 8.8 months (95% CI, 6.528-11.072) and 7.62 months (95% CI, 5.917-9.323) in the USG, respectively (P = 0.019). Median and mean overall survival were 10.4 months (95% CI, 8.383-12.417) and 9.953 months (95% CI, 8.408-11.498), respectively, in the ISG vs 9.7 months (95% CI, 7.901-11.499) and 8.14 months (95% CI, 6.44-9.84), respectively, in the USG (P = 0.027).

CONCLUSIONS

Irradiation stents extend stent patency and overall survival compared with conventional biliary stents for the treatment of pancreatic carcinoma complicated by obstructive jaundice. Irradiation stents combined with chemotherapy may be a better choice for the treatment of obstructive jaundice caused by unresectable pancreatic carcinoma.

Evaluation of Iodine-125 Interstitial Brachytherapy Using Micro-Positron Emission Tomography/Computed Tomography with 18F-Fluorodeoxyglucose in Hepatocellular Carcinoma HepG2 Xenografts

BACKGROUND Iodine-125 interstitial brachytherapy (125I-IBT) is a promising treatment option for unresectable hepatocellular carcinoma (HCC). This study evaluated the usefulness of micro-positron emission tomography/computed tomography (micro-PET/CT) with 18F-fluorodeoxyglucose (18F-FDG) in assessing response to 125I-IBT in HCC HepG2 xenograft. MATERIAL AND METHODS Twelve mice with bilateral HepG2 xenografts were divided into 3 equal groups implanted with iodine-125 seeds into the left xenografts with a dose of 30, 50, and 80 Gy, respectively, and the right xenografts were used as internal controls. Before and 28 days after treatment, the 18F-FDG micro-PET/CT was performed. The ratios of left to right xenografts of tumor volume (RTV), maximum standardized uptake value (RSUVmax), mean optical density of caspase-3 expression (RMODcaspase-3), and apoptosis index (RAI) were compared. RESULTS The RTV means of the 50 and 80 Gy groups were significantly lower than in the 30 Gy group after treatment (P<0.01) and the RTV means after treatment were lower than baseline in the 50 and 80 Gy groups (P<0.05). The RSUVmax mean after treatment was lower than baseline in the 80 Gy group (P<0.05). The RMODCaspase-3 and RAI means of the 80 Gy group were higher than in the 30 Gy group (P<0.05). The RSUVmax was correlated negatively to RMODcaspase-3 (r=-0.624, P<0.05) and RAI (r=-0.651, P<0.05). CONCLUSIONS This study suggest that 125I-IBT inhibits tumor growth via upregulating caspase-3 expression and prompting apoptosis in HCC HepG2 xenografts. The 18F-FDG micro-PET/CT may be a useful functional imaging modality to assess early response to 125I-IBT in HCC HepG2 xenograft.

Preliminary application of 3D-printed coplanar template for iodine-125 seed implantation therapy in patients with advanced pancreatic cancer

AIM

To evaluate a 3D-printed coplanar template for iodine-125 seed implantation therapy in patients with pancreatic cancer.

METHODS

A retrospective analysis of our database was performed, and a total of 25 patients with pancreatic cancer who underwent iodine-125 seed implantation between January 2014 and November 2017 were analyzed. Of these, 12 implantations were assisted by a 3D-printed coplanar template (group A), and 13 implantations performed freehand were selected as a control group (group B). A 3D coplanar template was designed and printed according to a preoperative CT scan and treatment planning system. The iodine-125 seeds were then implanted using the template as a guide. Dosimetric verification was performed after implantation. Pre- and postoperative D90, V100, and V150 were calculated. The success rate of iodine-125 seed implantation, dosimetric parameters, and complications were analyzed and compared between the two groups.

RESULTS

Iodine-125 seed implantation was successfully performed in both groups. In group A, the median pre- and postoperative D90 values were 155.32 ± 8.05 Gy and 154.82 ± 16.43 Gy, respectively; the difference between these values was minimal and not statistically significant (P > 0.05). Postoperative V100 and V150 were 91.05% ± 4.06% and 64.54% ± 13.40%, respectively, which met the treatment requirement. A better dosimetric parameter was observed in group A than in group B, and the difference was statistically significant (V100: 91.05% ± 4.06% vs 72.91% ± 13.78%, P < 0.05). No major procedure-related complications were observed in either group. For group A, mild hemorrhage was observed in 1 patient with a peritoneal local hematoma due to mesenteric vein damage from the iodine-125 seed implantation needle. The hematoma resolved spontaneously without treatment. Postoperative blood amylase levels remained within the normal range for all patients.

CONCLUSION

A 3D-printed coplanar template appears to be a safe and effective iodine-125 seed implantation guidance tool to improve implantation accuracy and optimize dosimetric distribution.

The effects of ultrasound exposure on P-glycoprotein-mediated multidrug resistance in vitro and in vivo

Background

Multidrug resistance (MDR) is often responsible for the failure of chemotherapy treatment, and current strategies for cancer MDR are not adequately satisfying as to their efficacy and safety. In this study, we sought to determine the anti-MDR effects of ultrasound (US) irradiation and its underlying mechanisms against drug-resistance.

Methods

MDR variant MCF-7/ADR cell lines and endothelial cell lines were used to determine the appropriate ultrasound intensity for in vitro experiments. MCF-7/ADR cell and HEPG2/ADM cells were used to assess the anti-MDR effect of US irradiation. Intracellular adriamycin (ADM) accumulation, Cell viability, cell proliferation and cell apoptosis were evaluated after ADM + US treatment or ADM treatment alone. MCF-7/ADR xenograft mice were used to investigate the appropriate ultrasound intensity for in vivo experiments and its effect on the long-term prognosis. Underlining mechanisms by which ultrasound exposure reversing MDR phenotype were investigated both in vitro and in vivo.

Results

Combination of ADM and 0.74 W/cm² US irradiation enhanced ADM intracellular concentration and nuclear accumulation in MCF-7/ADR and HEPG2/ADM cells, compared to those treated with ADM alone. Enhanced cellular ADM uptake and nuclei localization was associated with increased cytotoxicity of ADM to ADM-resistant cells, lower ADM-resistant cell viability and proliferative cell ratio, and higher apoptotic cell ratio. More importantly, US exposure increased the effectiveness of ADM to inhibit tumor growth in MCF-7/ADR xenograft mice. Mechanistically, US exposure promoted ADM accumulation in MDR cells mainly through down-regulation of P-glycoprotein (P-gp), which is dependent on US-induced intracellular reactive oxygen species (ROS) production. US-induced oxidative stress promoted miR-200c-3p and miR-34a-3p expression by forming miR-200c/34a/ZEB1 double-negative feedback loop. Finally, US-induced miR-200c/34a overexpression decreased P-gp expression and reversed MDR phenotype.

Conclusion

US irradiation could reverse MDR phenotype by activating ROS-ZEB1-miR200c/34a-P-gp signal pathway. Our findings offer a new and promising strategy for sensitizing cells to combat MDR and to improve the therapeutic index of chemotherapy.

Electronic supplementary material

The online version of this article (10.1186/s13046-018-0900-6) contains supplementary material, which is available to authorized users.

Iodine-125 interstitial brachytherapy reduces tumor growth via Warburg effect inhibition in non-small cell lung cancer A549 ×enografts

Iodine-125 interstitial brachytherapy (125I-IBT) is an alternative and effective treatment option for unresectable non-small cell lung cancer (NSCLC), and the Warburg effect is a determinant of tumor growth. The present study aimed to explore the influence of 125I-IBT on tumor growth and the Warburg effect, and the potential mechanisms underlying NSCLC progression. Mice with A549 cell xenografts were evenly divided into a control group without 125I-IBT, and three treatment groups receiving 125I-IBT with 20, 40 and 60 Gy. Tumor volume (TV), maximum standardized uptake value (SUVmax) determined by 18F-fluorodeoxyglucose (18F-FDG) micro-positron emission tomography/computed tomography and mean optical density (MOD) of mammalian target of rapamycin (mTOR), c-Myc, hypoxia inducible factor-1α (HIF-1α) and glucose transporter 1 (GLUT1) staining were compared among groups. Tumor inhibition rate (TIR), 18F-FDG uptake attenuation rate (FUAR) and expression suppression rate (ESR) were also calculated on day 14 and 28. The results demonstrated that the mean TV in the 60 and 40 Gy groups was smaller compared with the control TVs since days 14 and 16, respectively. The mean SUVmax value of the 60 Gy group at day 14, and all treatment group SUVmax values at day 28 were lower compared with the controls. In addition, the MOD of mTOR and GLUT1 was lower in the 60 Gy group, compared with the other groups, and c-Myc and HIF-1α values were lower in the 40 and 60 Gy groups, compared with the control and 20 Gy group (P<0.05). SUVmax positively correlated to TV (day 14, r=0.711; day 28, r=0.586) and the MOD of c-Myc and GLUT1 (r=0.621 and 0.546, respectively; P<0.01). Furthermore, dose dependent increases were observed for TIR, FUAR and ESR. In conclusion, 125I-IBT reduced tumor growth by inhibiting the Warburg effect, which may have resulted from downregulation of mTOR, c-Myc, HIF-1α and GLUT1 expression, particularly c-Myc and GLUT1, in NSCLC A549 ×enografts.

Permeable gastric ulcer caused by radioactive 125I seed implantation for adrenal metastasis: A case report and literatures review

Radioactive ¹²⁵I seed implantation as a means of radiotherapy for malignant tumors has been proved to be safe and effective. Although the effectiveness of ¹²⁵I seed implantation in the treatment of tumor metastases has been widely recognized, there is still no standard for the selection of radiation doses. Adrenal blood supply is abundant, and it is a common metastatic site for malignant tumors. CT-guided radioactive ¹²⁵I seed implantation is effective in treating adrenal metastases. However, it may cause certain damage to surrounding organs, especially the stomach. Clinically, for patients with left adrenal metastatic carcinoma and concurrent radioactive seed implantation, the occurrence of permeable gastric ulcer should not be neglected. In order to reduce the effect of radioactive particles on the normal tissue structure around the tumor, low-activity particles should be used.

Multiparametric MR imaging detects therapy efficacy of radioactive seeds brachytherapy in pancreatic ductal adenocarcinoma xenografts

OBJECTIVE

To investigate the therapeutic efficacy of Iodine-125 (¹²⁵I) seeds brachytherapy to pancreatic ductal adenocarcinoma (PDAC) xenografts via multiparametric magnetic resonance imaging (MRI) analysis.

MATERIALS AND METHODS

Twenty mice were implanted subcutaneously with SW-1990 PDAC xenografts. The tumor-bearing mice were randomly divided into ¹²⁵I seeds group (n = 10) and blank control group (n = 10). Treatment response was monitored by diffusion-weighted magnetic resonance imaging (DW-MRI) and dynamic contrast-enhanced MRI (DCE-MRI) obtained 1 day before, 14 and 60 days after treatment. Imaging results were correlated with histopathology.

RESULTS

¹²⁵I seeds brachytherapy resulted in a significant increase in mean tumor apparent diffusion coefficient (ADC) values compared to the control at 14 and 60 days after treatment (p < 0.05). DCE-MRI showed a significant decrease in the perfusion parameters including K^trans and K_ep (p < 0.05). The mean ADCs within the peripheral region of the tumors were linearly proportional to the mean apoptotic cell density (p = 0.015; Spearman's coefficient = 0.945). The K^trans and K_ep were linearly proportional to microvessel density (MVD) (p = 0.043, 0.047; Spearman's coefficient = 0.891, 0.884).

CONCLUSION

¹²⁵I seeds brachytherapy leads to effective inhibition of PDAC cell proliferation, higher degree of necrosis and necroptosis, and lower MVD. Both DW-MRI and DCE-MRI are feasible to monitor a response to ¹²⁵I seeds brachytherapy in the PDAC xenografts. This paper shows an original project concerning about a possible palliative treatment not only in a murine model (preclinical setting) but also in humans.

Surgical bypass and permanent iodine-125 seed implantation vs. surgical bypass for the treatment of pancreatic head cancer

The present study aimed to investigate the efficacy and safety of Iodine-125 (¹²⁵I) seed implantation in the treatment of locally advanced unresectable pancreatic head cancer. A prospective nonrandomized study was performed using data collected from patients between January 2009 and December 2012. A total of 34 patients underwent surgical bypass and permanent ¹²⁵I seed implantation (group A), and 32 patients underwent biliary and gastric bypass (group B). The preoperative variables, operative data, postoperative complications and follow-up information were examined. No significant differences were identified in clinical characteristics, mortality, morbidity and length of hospital stay between the two groups. Tumor responses were significantly different between between patients in group A and B (partial response, 56 vs. 0%, P<0.001; progression, 24 vs. 84%, P=0.013). The time until disease progression was significantly longer in group A compared to group B (8±1 vs. 5±2 months; P<0.001). The median survival time was significantly longer in group A compared to group B (11 vs. 7 months; P<0.001). The quality of life was improved significantly in group A compared to group B. In the first month following surgery, pain scores were improved (24±10 vs. 54±19; P<0.001). Following repeated measure analysis, pain scores were significantly lower in group A compared to group B (P<0.05) at 9 months following surgery. The results of the present study suggest that ¹²⁵I seed implantation is feasible, safe and effective for the treatment of unresectable pancreatic head cancer.

Combination of 125I brachytherapy and chemotherapy for unresectable recurrent breast cancer: A retrospective control study

Recurrent breast cancer remains an incurable malignancy and cannot be removed by surgery in the majority of cases. This study aimed to explore the feasibility and efficacy of the combination of I brachytherapy and chemotherapy for the treatment of unresectable recurrent breast cancer. Patients with unresectable recurrent breast cancer treated between January 2011 and December 2014 with a combination of I brachytherapy and capecitabine or gemcitabine were evaluated and outcomes were compared with those of women treated with capecitabine or gemcitabine in conventional dose as a monotherapy. Of 61 patients evaluated, 28 received the combination treatment and 33 received capecitabine or gemcitabine monotherapy. The combination of I brachytherapy and chemotherapy resulted in a significant improvement in progression-free survival versus capecitabine or gemcitabine monotherapy (median, 17.8 vs 11.4 months; hazard ratio [HR], 0.44; 95% confidence interval [CI], 0.23-0.84; P = 0.013). The objective response rate (ORR) was significantly higher with the combination (82.1%) than with monotherapy (54.5%; P = 0.022), and the rate of pain relief was higher in the combination arm (100% vs 73.6%; P = 0.038). There was no significant improvement for overall survival (median, 30.1 vs 27.2 months; HR, 0.82; 95% CI, 0.47-1.44; P = 0.496). There were no serious complications detected during the follow-up period, any grade toxicities were comparable between treatment arms. In conclusion, the combination of I brachytherapy and second-line chemotherapy is superior to chemotherapy alone and is an effective and safe therapy for unresectable recurrent breast cancer. However, further investigation and much larger scale randomized controlled trials with long-term follow-up are needed.

Iodine-125 irradiation inhibits invasion of gastric cancer cells by reactivating microRNA-181c expression

Iodine-125 (¹²⁵I) seed implantation has been widely used for the treatment of unresectable advanced tumors. However, the molecular mechanisms underlying the tumor-suppressive effects of ¹²⁵I irradiation have not been fully elucidated. The present study demonstrated that ¹²⁵I irradiation suppresses cell viability and inhibits cell invasiveness of gastric cancer KATO-III and MKN45 cells. Further mechanistic analysis suggested the involvement of microRNA (miR)-181c in the inhibitory effects induced by ¹²⁵I irradiation. Methylated DNA immunoprecipitation coupled with quantitative-polymerase chain reaction demonstrated that treatment with ¹²⁵I irradiation, at the dose of 4 Gy, induced promoter demethylation of the miR-181c gene in KATO-III and MKN45 cells. Following irradiation, the expression of miR-181c was significantly increased, which may be attributed to the demethylation caused by ¹²⁵I irradiation. In addition, upregulation of miR-181c by administration of miR-181c mimics decreased cell invasion, suggesting the role of miR-181c as a tumor suppressor. More importantly, the tumor-suppressive effects of ¹²⁵I irradiation were significantly compromised by the introduction of miR-181c inhibitors. Overall, these results reveal that ¹²⁵I irradiation inhibits invasiveness of gastric cancer cells by reactivating miR-181c at the epigenetic level, thereby providing important molecular evidence for the anticancer effects of ¹²⁵I irradiation.

Advancement in treatment and diagnosis of pancreatic cancer with radiopharmaceuticals

Pancreatic cancer (PC) is a major health problem. Conventional imaging modalities show limited accuracy for reliable assessment of the tumor. Recent researches suggest that molecular imaging techniques with tracers provide more biologically relevant information and are benefit for the diagnosis of the cancer. In addition, radiopharmaceuticals also play more important roles in treatment of the disease. This review summaries the advancement of the radiolabeled compounds in the theranostics of PC.

Novel Silicone-Coated 125I Seeds for the Treatment of Extrahepatic Cholangiocarcinoma

125I seeds coated with titanium are considered a safe and effective interstitial brachytherapy for tumors, while the cost of 125I seeds is a major problem for the patients implanting lots of seeds. The aim of this paper was to develop a novel silicone coating for 125I seeds with a lower cost. In order to show the radionuclide utilization ratio, the silicone was coated onto the seeds using the electro-spinning method and the radioactivity was evaluated, then the anti-tumor efficacy of silicone 125I seeds was compared with titanium 125I seeds. The seeds were divided into four groups: A (control), B (pure silicone), C (silicone 125I), D (titanium 125I) at 2 Gy or 4 Gy. Their anti-tumour activity and mechanism were assessed in vitro and in vivo using a human extrahepatic cholangiocarcinoma cell line FRH-0201 and tumor-bearing BALB/c nude mice. The silicone 125I seeds showed higher radioactivity; the rate of cell apoptosis in vitro and the histopathology in vivo demonstrated that the silicone 125I seeds shared similar anti-tumor efficacy with the titanium 125I seeds for the treatment of extrahepatic cholangiocarcinoma, while they have a much lower cost.

Enhanced EJ Cell Killing of (125)I Radiation by Combining with Cytosine Deaminase Gene Therapy Regulated by Synthetic Radio-Responsive Promoter

Aim: To investigate the enhancing effect of radionuclide therapy by the therapeutic gene placed under the control of radio-responsive promoter.

Methods: The recombinant lentivirus E8-codA-GFP, including a synthetic radiation-sensitive promoter E8, cytosine deaminase (CD) gene, and green fluorescent protein gene, was constructed. The gene expression activated by ¹²⁵I radiation was assessed by observation of green fluorescence. The ability of converting 5-fluorocytosine (5-FC) to 5-fluorourial (5-FU) by CD enzyme was assessed by high-performance liquid chromatography. The viability of the infected cells exposed to ¹²⁵I in the presence of 5-FC was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, and the infected cells exposed to ¹²⁵I alone served as negative control and 5-FU as positive control.

Results: The recombinant lentiviral vector was constructed successfully. On exposure of infected cells to ¹²⁵I, green fluorescence can be observed and 5-FU can be detected. MTT assay showed that the survival rate for infected cells treated with ¹²⁵I was lower compared with the ¹²⁵I control group, but higher than the positive control group.

Conclusion: The synthetic promoter E8 can induce the expression of downstream CD gene under ¹²⁵I radiation, and the tumor killing effect of ¹²⁵I can be enhanced by combining CD gene therapy with radiosensitive promoter.

The clinical utility of image-guided iodine-125 seed in patients with unresectable pancreatic cancer

In the present study, we investigated the clinical effects of image-guided iodine-125 ((125)I) seed on unresectable pancreatic cancer. Twenty-five patients with unresectable pancreatic cancer were enrolled in this study, including 13 patients with seed implantation and 12 patients as control. The survival status, clinical benefits, objective curative effects, and relevant tumor markers were analyzed to assess the feasibility and safety of interstitial (125)I seed implantation. We found that the clinical benefit rate of the seed implantation group is 92.3 % (12/13), compared with 41.7 % (5/12) in the control, and the difference was statistically significant (p < 0.01). Compared with control, patients with seed implantation had significantly shorter operative time, less bleeding, higher albumin, shorter periods to bowel movement, and normal diet as well as lower risk of complications (p < 0.001). The differences of objective curative effects adverse effects, complications, and median survival between these two groups were not significant statistically (p > 0.05). In conclusion, (125)I seed implantation provides a safe and effective method to inhibit the tumor development, relieve pain, and improve quality of life for unresectable pancreatic cancer. These findings need to be validated by conducting further studies with larger cohorts.

Biological effects of low-dose-rate irradiation of pancreatic carcinoma cells in vitro using 125I seeds

AIM: To determine the mechanism of the radiation-induced biological effects of ¹²⁵I seeds on pancreatic carcinoma cells in vitro.

METHODS: SW1990 and PANC-1 pancreatic cancer cell lines were cultured in DMEM in a suitable environment. Gray’s model of iodine-125 (¹²⁵I) seed irradiation was used. In vitro, exponential phase SW1990, and PANC-1 cells were exposed to 0, 2, 4, 6, and 8 Gy using ¹²⁵I radioactive seeds, with an initial dose rate of 12.13 cGy/h. A clonogenic survival experiment was performed to observe the ability of the cells to maintain their clonogenic capacity and to form colonies. Cell-cycle and apoptosis analyses were conducted to detect the apoptosis percentage in the SW1990 and PANC-1 cells. DNA synthesis was measured via a tritiated thymidine (³H-TdR) incorporation experiment. After continuous low-dose-rate irradiation with ¹²⁵I radioactive seeds, the survival fractions at 2 Gy (SF2), percentage apoptosis, and cell cycle phases of the SW1990 and PANC-1 pancreatic cancer cell lines were calculated and compared.

RESULTS: The survival fractions of the PANC-1 and SW1990 cells irradiated with ¹²⁵I seeds decreased exponentially as the dose increased. No significant difference in SF2 was observed between SW1990 and PANC-1 cells (0.766 ± 0.063 vs 0.729 ± 0.045, P < 0.05). The ¹²⁵I seeds induced a higher percentage of apoptosis than that observed in the control in both the SW1990 and PANC-1 cells. The rate of apoptosis increased with increasing radiation dosage. The percentage of apoptosis was slightly higher in the SW1990 cells than in the PANC-1 cells. Dose-dependent G2/M cell-cycle arrest was observed after ¹²⁵I seed irradiation, with a peak value at 6 Gy. As the dose increased, the percentage of G2/M cell cycle arrest increased in both cell lines, whereas the rate of DNA incorporation decreased. In the ³H-TdR incorporation experiment, the dosimetry results of both the SW1990 and PANC-1 cells decreased as the radiation dose increased, with a minimum at 6 Gy. There were no significant differences in the dosimetry results of the two cell lines when they were exposed to the same dose of radiation.

CONCLUSION: The pancreatic cancer cell-killing effects induced by ¹²⁵I radioactive seeds mainly occurred via apoptosis and G2/M cell cycle arrest.

Loss of EGF-dependent cell proliferation ability on radioresistant cell HepG2-8960-R

Acquired radioresistance of cancer cells interferes with radiotherapy and increases the probability of cancer recurrence. HepG2-8960-R, which is one of several clinically relevant radioresistant (CRR) cell lines, has a high tolerance to the repeated clinically relevant doses of X-ray radiation. In this study, HepG2-8960-R had slightly lower cell proliferation ability than HepG2 in the presence of FBS. In particular, epidermal growth factor (EGF) hardly enhanced cell proliferation and DNA synthesis in HepG2-8960-R. Additionally, EGF could not induce the activation of Erk1/2, because the expression of EGF receptor (EGFR) protein decreased in HepG2-8960-R in accordance with the methylation of the EGFR promoter region. Therefore, cetuximab did not inhibit HepG2-8960-R cell proliferation. Our study showed that HepG2-8960-R had radioresistant and cetuximab-resistant abilities.

ATL

Objective

The aim of this study was to evaluate the effectiveness and safety of percutaneous interstitial implantation with125I seed under computed tomographic (CT) guidance for recurrent ovarian cancer (ROC).

Materials and Methods

A retrospective review was performed on 17 patients with ROC who were treated with125I seed brachytherapy. Treatment planning system was used preoperatively to determine the estimated seeds number and distribution;125I seeds were implanted into recurrent lesions under CT guidance. Therapeutic effectiveness and complications were noted during follow-up time.

Results

Months are counted from the time of125I seed brachytherapy, and the median duration of follow-up was 10.5 months (3-23 months). The objective response rates after 1, 3, 6, 12, and 18 months were 76.5%, 75.0%, 61.5%, 42.9%, and 40%, respectively. The pain relief rate was 61.5%, and the general living quality was improved dramatically. The median progression-free survival time was 5.4 months, the median overall survival time was 11.3 months, and the 1-year survival rate was 41.2%. Complications in this study were very mild; severe adverse events such as massive bleeding, intestinal fistula, and treatment-related deaths did not occur.

Conclusions

Our initial experience showed that CT-guided125I seed interstitial implantation is safe and feasible in the treatment of patients with ROCs after multiple therapies.

Effect of brachytherapy on NF-κB and VEGF in gastric carcinoma xenografts

Iodine-125 (125I) seed irradiation can be used as an important supplementary treatment for unresectable advanced gastric cancer. However, the radiobiological mechanism underlying brachytherapy remains unclear. Therefore, we investigated the influence of continuous and low-energy 125I irradiation on the cell cycle distribution, apoptosis, expression of NF-κB and VEGF and tumor growth in a human gastric cancer xenograft model. To create an animal model of gastric cancer, SGC-7901 cells were surgically implanted into mice. The 60 mice bearing SGC-7901 gastric cancer xenografts were randomly separated into 2 groups. Sham seeds (0 mCi) were implanted into the control group (n=30); 125I seeds (0.6 mCi) were implanted into the treatment group (n=30). At 28 days after irradiation, apoptosis was detected by flow cytometry. fluorescence micrograph detected intense VEGF and NF-κB immunofluorescence in the tumor samples, and changes in NF-κB and VEGF mRNA and protein expression were assessed by real-time PCR and western blot analysis, respectively. The tumor volume and weight were measured 0-28 days after 125I seed implantation. 125I seed irradiation induced significant apoptosis and G2/M phase arrest. Reduction in the intensities of VEGF and NF-κB immunofluorescence in tumor vessels was observed after treatment. NF-κB and VEGF mRNA and protein expression levels were substantially lower in the implantation treatment group than in the control group. Consequently, 125I seed implantation inhibited cancer growth and reduced cancer volume. The present study revealed that 125I seed irradiation significantly induced apoptosis and cell cycle arrest in the human gastric cancer xenografts. 125I-induced changes in NF-κB and VEGF expression are suggested as potential mechanisms underlying effective brachytherapy.

The investigation of 125I seed implantation as a salvage modality for unresectable pancreatic carcinoma

BACKGROUND

To assess the efficacy of intraoperative ultrasound-guided implantation of 125I seeds for the treatment of unresectable pancreatic carcinoma, and analyze the associated prognostic factors.

METHODS

Twenty-eight patients with pancreatic carcinoma who underwent laparotomy and were considered to have unresectable tumors were included in this study. Nine patients were pathologically diagnosed with Stage II disease, and nineteen patients with Stage III disease. Twenty-eight patients received intraoperative ultrasound-guided 125I seed implantation and received a D90 (at least 90% of the tumor volume received the reference dose) ranging from 60 to 163 Gy, with a median of 120 Gy. Seven patients received an additional 35-50 Gy external beam radiotherapy after seed implantation, and ten patients received two to ten cycles of chemotherapy. Overall survival of the patients was calculated and prognostic factors were evaluated.

RESULTS

Of the patients, 94.1% (16/17) achieved good to medium pain relief. The tumor response rate was 78.6% (22/28), and local control was achieved in 85.7% (24/28) of patients. The 1-, 2- and 3-year survival rates were 30%, 11% and 4%, and the median survival was 10.1 months (95% CI: 9.0-10.9). Analysis using the Cox proportional hazards model suggested that patients younger than 60 years and patients who received a D90 higher than 110 Gy may survive for a longer period.

CONCLUSIONS

I seed implantation provides a safe and effective method to relieve pain, control local tumor growth and, to some extent, prolong the survival of patients with stage II and III pancreatic disease, without additional complications. Age and accumulated dose may be factors predictive of a favorable outcome for patients with unresectable pancreatic carcinoma treated with 125I seeds. These findings need to be validated by conducting further studies with larger cohorts.

Aberrant DNA methyltransferase expression in pancreatic ductal adenocarcinoma development and progression

BACKGROUND

Altered gene methylation, regulated by DNA methyltransferases (DNMT) 1, 3a and 3b, contributes to tumorigenesis. However, the role of DNMT in pancreatic ductal adenocarcinoma (PDAC) remains unknown.

METHODS

Expression of DNMT 1, 3a and 3b was detected in 88 Pancreatic ductal adenocarcinoma (PDAC) and 10 normal tissue samples by immunohistochemistry. Changes in cell viability, cell cycle distribution, and apoptosis of PDAC cell lines (Panc-1 and SW1990) were assessed after transfection with DNMT1 and 3b siRNA. Levels of CDKN1A, Bcl-2 and Bax mRNA were assessed by qRT-PCR, and methylation of the Bax gene promoter was assayed by methylation-specific PCR (MSP).

RESULTS

DNMT1, 3a and 3b proteins were expressed in 46.6%, 23.9%, and 77.3% of PDAC tissues, respectively, but were not expressed in normal pancreatic tissues. There was a co-presence of DNMT3a and DNMT3b expression and an association of DNMT1 expression with alcohol consumption and poor overall survival. Moreover, knockdown of DNMT1 and DNMT3b expression significantly inhibited PDAC cell viability, decreased S-phase but increased G1-phase of the cell cycle, and induced apoptosis. Molecularly, expression of CDKN1A and Bax mRNA was upregulated, and the Bax gene promoter was demethylated. However, a synergistic effect of combined DNMT1 and 3b knockdown was not observed.

CONCLUSION

Expression of DNMT1, 3a and 3b proteins is increased in PDAC tissues, and DNMT1 expression is associated with poor prognosis of patients. Knockdown of DNMT1 and 3b expression arrests tumor cells at the G1 phase of the cell cycle and induces apoptosis. The data suggest that DNMT knockdown may be a novel treatment strategy for PDAC.

Continuous low-dose irradiation by I-125 seeds induces apoptosis of gastric cancer cells regardless of histological origin

The efficacy of conventional radiation therapy for gastric cancer is controversial. In this study, we evaluated the in vitro and in vivo effects of continuous low-dose-rate irradiation by I-125 seeds on different histological types of gastric cancer cell lines. Three human gastric cancer cell lines (MKN74, MKN45, and NUGC4) were treated with or without continuous low-dose irradiation by I-125 seeds in vitro and in vivo. Cell viability, apoptosis, caspase-3 assay, and cell-cycle distribution were examined in vitro. Body weight and tumor volumes of BALB/c nude mice bearing MKN74, MKN45, and NUGC4 gastric cancer xenografts were measured, and in vivo cell proliferation and apoptosis assays were performed by Ki67 and TUNEL staining, respectively. Continuous low-dose-rate irradiation by I-125 seeds reduced cell viability and induced cell apoptosis through the activation of caspase-3, and led to the accumulation of cells in the G 2/M phase in vitro. It also suppressed the growth of gastric cancer xenografts in nude mice, while inhibiting cell proliferation and inducing apoptosis as demonstrated by Ki67 and TUNEL staining. Therefore, our data suggest that continuous low-dose-rate irradiation by I-125 seeds could be a promising new option for gastric cancer treatment, regardless of histological origin.

Effects of iodine-125 seeds on the methylation of SFRP2 and P16 in colorectal cancer

The current study investigated the effects of iodine-125 seeds on the gene methylation of SFRP₂ and P16 in colorectal cancer. Mouse models of human colorectal cancer were randomly divided into an experimental group (n=25) and a control group (n=25). The control group was implanted with blank seeds (0 MBq) and the experimental group with iodine-125 seeds (14.8 MBq). At 20 days after implantation, the animals were sacrificed. The methylation levels of SFRP₂ and P16 were detected using methylation-specific polymerase chain reactions (MSPs). Following iodine-125 seed irradiation, the level of SFRP₂ methylation decreased. The methylation index of the experimental group (0.67±0.05) was significantly lower than that of the control group (0.84±0.07; P<0.05). In the experimental group, 10 samples (40%) displayed methylation in the P16 promoter region compared with 14 (56%) in the control group, which was a significant difference (P<0.05). Iodine-125 seeds induce the downregulation of methylated tumor suppressor gene promoters, thereby inhibiting the proliferation and growth of tumor cells.

Iodine-125 seeds strand for treatment of tumor thrombus in inferior vena cava: an experimental study in a rabbit model

OBJECTIVE

The purpose of this study was to establish an animal model of implanted inferior vena cava tumor thrombus (IVCTT) and to evaluate the effect of linear iodine-125 seeds strand in treating implanted IVCTT.

METHODS

Tumor cell line VX2 was inoculated subcutaneously into New Zealand rabbit to develop the parent tumor. The tumor strip was inoculated into inferior vena cava (IVC) to establish the IVCTT model. The IVCTT was confirmed by multidetector computed tomography (MDCT) after 2 weeks. Twelve rabbits with IVCTT were randomly divided into two groups. Treatment group (group T; n = 6) underwent Iodine-125 seeds brachytherapy, and the control group (group C; n = 6) underwent blank seeds strand. The blood laboratory examination (including blood routine examination, hepatic and renal function), body weight, survival time, and IVCTT volume by MDCT were monitored. All rabbits were dissected postmortem, and the therapeutic effects were evaluated on the basis of histopathology. The proliferating cell nuclear antigen index (PI) and apoptosis index (AI) of IVCTT were compared between two groups. T test, Wilcoxon rank test, and Kaplan-Meier survival curve analysis were used.

RESULTS

The success rate of establishing IVCTT was 100 %. The body weight loss and cachexia of rabbits in group C appeared earlier than in group T. Body weight in the third week, the mean survival time, PI, AI in groups T and C were 2.23 ± 0.12 kg, 57.83 ± 8.68 days, (16.73 ± 5.18 %), (29.47 ± 7.18 %), and 2.03 ± 0.13 kg, 43.67 ± 5.28 days, (63.01 ± 2.01 %), (6.02 ± 2.93 %), respectively. There were statistically significant differences between group T and group C (P < 0.05). The IVCTT volume of group T was remarkably smaller than that of group C.

CONCLUSIONS

Injecting and suspensory fixing VX2 tumor strip into IVC is a reliable method to establish IVCTT animal model. The linear Iodine-125 seeds strand brachytherapy was a safe and effective method for treating IVCTT in rabbit model.

125I seed irradiation induces up-regulation of the genes associated with apoptosis and cell cycle arrest and inhibits growth of gastric cancer xenografts

Background

Iodine 125 (125I) seed irradiation can be used as an important supplementary treatment for unresectable advanced gastric cancer. Here, we aim to comprehensively elucidate the biological effects induced by 125I seed irradiation in human gastric cancer xenograft model by using global expression and DNA methylation analyses.

Methods

The 48 mice bearing NCI-N87 gastric cancer xenografts were randomly separated into 2 groups: sham seeds (O mCi) were implanted into the control group (n = 24); 125 l seeds (0.9 mCi) were implanted into the treatment group (n = 24). The mitotic index and apoptotic index were evaluated by quantitative morphometric analysis of the expression of proliferating cell nuclear antigen (PCNA) and in situ terminal transferase-mediated fluorescein deoxy- UTP nick end labeling (TUNEL), respectively. Global gene expression changes induced by 125I seed irradiation were analyzed by using Nimblegen Human gene expression array. DNA methylation profile in the tumors from control group was investigated with methylated DNA immunoprecipitation (MeDIP) and Nimblegen CpG promoter microarrays. The changes in the methylation status of selected genes were further investigated by using MeDIP-PCR.

Results

125I seed irradiation suppresses the growth of gastric cancer xenografts in nude mice. PCNA staining and tissue TUNEL assays showed that both inhibition of cell proliferation and induction of apoptosis contribute to the 125I-induced tumor suppression in nude mouse model. Gene expression profiles revealed that the expression levels of several hundred genes, many of which are associated with apoptosis or cell cycle arrest, including BMF, MAPK8, BNIP3, RFWD3, CDKN2B and WNT9A, were upregulated following 125I seed irradiation. Furthermore, the up-regulation of some of these genes, such as BNIP3 and WNT9A, was found to be associated with irradiation-induced DNA demethylation.

Conclusions

This study revealed that 125I seed irradiation could significantly induce the up-regulation of apoptosis- and cell cycle-related genes in human gastric cancer xenografts. And some of the up-regulation might be attributed to 125I-irradiation induced demethylation in gene promoter regions. Collectively, these findings provided evidence for the efficacy of this modality for the treatment of gastric cancer.