Mao Bin Meng

Mesenchymal stem cells generate pericytes to promote tumor recurrence via vasculogenesis after stereotactic body radiation therapy.

BACKGROUND Stereotactic body radiation therapy (SBRT) is postulated to enhance the recruitment of mesenchymal stem cells (MSCs) into the tumor microenvironment, which promote tumor recurrence. The aim of this study is to determine the molecular mechanisms behind SBRT stimulating MSC migration and differentiation. METHODS In vitro, mediated factors and migrated MSCs (post-SBRT) were generated. In vivo, bone-marrow derived MSCs were identified and harvested from green fluorescent protein (GFP)-expressing transgenic male mice and transplanted into sub-lethally irradiated recipient female mice to establish a model of bone marrow transplantation. Lewis lung carcinoma and malignant melanoma-bearing recipient mice were treated with SBRT, 14 Gy/1 fraction. The migration and differentiation potential of MSCs were characterized. RESULTS SBRT increased the release of stromal cell derived factor-1α (SDF-1α) and platelet-derived growth factor-B (PDGF-B) by tumor cells; these ligands bound to chemokine (C-X-C motif) receptor 4 (CXCR4) and platelet-derived growth factor receptor-β (PDGFR-β), respectively, on circulating bone marrow-derived MSCs, resulting in engraftment of the MSCs into the tumor parenchyma. The newly-homed MSCs differentiated into pericytes, which induced the tumor vasculogenesis, and promoted tumor regrowth. Targeted therapies, AMD3100 and imatinib abrogated MSC homing, vasculogenesis, and tumor regrowth. CONCLUSION Bone-marrow derived MSCs migrate to the tumor parenchyma and differentiate into pericytes, inducing tumor vasculogenesis after SBRT, and promoting tumor recurrence. MSC migration and maturation may be abrogated with AMD3100 and imatinib. This novel treatment strategy warrants clinical investigation.

Targeting pyruvate kinase M2 contributes to radiosensitivity of non-small cell lung cancer cells in vitro and in vivo

Aerobic glycolysis, a metabolic hallmark of cancer, is associated with radioresistance in non-small cell lung cancer (NSCLC). Pyruvate kinase M2 isoform (PKM2), a key regulator of glycolysis, is expressed exclusively in cancers. However, the impact of PKM2 silencing on the radiosensitivity of NSCLC has not been explored. Here, we show a plasmid of shRNA-PKM2 for expressing a short hairpin RNA targeting PKM2 (pshRNA-PKM2) and demonstrate that treatment with pshRNA-PKM2 effectively inhibits PKM2 expression in NSCLC cell lines and xenografts. Silencing of PKM2 expression enhanced ionizing radiation (IR)-induced apoptosis and autophagy in vitro and in vivo, accompanied by inhibiting AKT and PDK1 phosphorylation, but enhanced ERK and GSK3β phosphorylation. These results demonstrated that knockdown of PKM2 expression enhances the radiosensitivity of NSCLC cell lines and xenografts as well as may aid in the design of new therapies for the treatment of NSCLC.

Pericytes: a double-edged sword in cancer therapy

Pericytes, which envelope the vascular endothelium throughout the body, are often targeted to promote vascular normalization and restore normal function of blood vessels in cancer treatment. The goals of pericyte-targeted therapy tend to promote proper vascular normalization of the tumor. Tumor vascular normalization prevents metastasis, increases tumor oxygenation (making radiation more effective in killing tumor cells), optimizes Starling forces to increase delivery of cancer cell-directed therapies (e.g., chemotherapy or targeted agents), increases the efficacy of focal therapies (e.g., surgery or radiation), and increases recognition by the host immune system. We review how approaches in pericyte-targeted therapy aim to reach a balance between pro-angiogenic and anti-angiogenic function (i.e., by targeting platelet-derived growth factor beta receptors, vascular endothelial growth factor receptors and Tie-2) for tumor vascular normalization.

Radiotherapy and chemotherapy are associated with improved outcomes over surgery and chemotherapy in the management of limited-stage small cell esophageal carcinoma

BACKGROUND This retrospective study evaluates the efficacy and safety of surgery and chemotherapy (S +CT) vs. radiotherapy and CT (RT+CT) in patients with limited stage small cell esophageal cancer (LS-SCEC). PATIENTS AND METHODS Patients included in analysis (from our hospital and the literature) were treated with S+CT or RT+CT between 1989 and 2012. The primary end point was overall survival (OS); secondary end points included tumor response and toxicity. Kaplan-Meier OS curves were compared with the log-rank test. Cox regression analysis was used to determine prognosticators for OS. RESULTS A total of 127 patients were included: 14 from our hospital and 113 from the literature. Fifty-four (43%) and 73 (57%) patients received S+CT or RT+CT, respectively. The median OS of all patients was 21.0 months. OS was longer for those who received RT+CT rather than S+CT (33.0 vs. 17.5 months, p=0.02), especially those with N1 disease. Uni- and multi-variate analyses showed tumor location (upper 1/3rd of esophagus) and type of treatment (S+CT) were poor prognostic factors of OS. CONCLUSION LS-SCEC patients treated with RT+CT had an improved OS compared to those treated with S+RT. Thus, RT+CT should be considered as a primary approach for these patients.

Stereotactic body radiation therapy using the CyberKnife(®) system for patients with liver metastases.

The aim of this study was to evaluate the efficacy and toxicity of stereotactic body radiation therapy (SBRT) in the treatment of patients with liver metastases. Between August 2006 and July 2011, patients with 1–4 liver metastases were enrolled and treated with SBRT using the CyberKnife® system at Tianjin Medical University Cancer Institute and Hospital. The metastases were from different primary tumors, with a maximum tumor diameter of less than 6 cm. The primary endpoint was local control. Secondary endpoints were overall survival, progression-free survival, distant progression-free survival, and adverse events. Fifty-seven patients with 80 lesions were treated with SBRT. The 1-year and 2-year local control rates were 94.4% and 89.7%, respectively. The difference in local control between patients who received adjuvant treatment before SBRT and those who did not reached statistical significance (P=0.049). The median overall survival for the entire cohort was 37.5 months. According to the primary tumor sites, the median overall survival was not reached. The 2-year overall survival rate was 72.2% in the favorable group (primary tumors originating from the colon, breast, or stomach, as well as sarcomas); however, in the unfavorable group (primary tumors originating from the pancreas, lung, ovary, gallbladder, uterus, hepatocellular carcinoma, as well as olfactory neuroblastoma), the median overall survival and 2-year overall survival rates were 37.5 months and 55.9%, respectively (P=0.0001). Grade 1–2 fatigue, nausea, and vomiting were the most common adverse events, and no grade 3 and higher adverse events were observed. With excellent local control in the absence of severe toxicity, SBRT provides an alternative for patients with 1–4 liver metastases who cannot undergo surgery or other treatments.

Necroptosis in tumorigenesis, activation of anti-tumor immunity, and cancer therapy.

While the mechanisms underlying apoptosis and autophagy have been well characterized over recent decades, another regulated cell death event, necroptosis, remains poorly understood. Elucidating the signaling networks involved in the regulation of necroptosis may allow this form of regulated cell death to be exploited for diagnosis and treatment of cancer, and will contribute to the understanding of the complex tumor microenvironment. In this review, we have summarized the mechanisms and regulation of necroptosis, the converging and diverging features of necroptosis in tumorigenesis, activation of anti-tumor immunity, and cancer therapy, as well as attempts to exploit this newly gained knowledge to provide therapeutics for cancer.

Stereotactic body radiation therapy for patients with recurrent pancreatic adenocarcinoma at the abdominal lymph nodes or postoperative stump including pancreatic stump and other stump

Background and aim The aim of this study is to evaluate the efficacy and safety of stereotactic body radiation therapy (SBRT) using CyberKnife in the treatment of patients with recurrent pancreatic adenocarcinoma at the abdominal lymph node or stump after surgery. Patients and methods Between October 1, 2006 and May 1, 2015, patients with recurrent pancreatic adenocarcinoma at the abdominal lymph node or stump after surgery were enrolled and treated with SBRT at our hospital. The primary end point was local control rate after SBRT. Secondary end points were overall survival, time to symptom alleviation, and toxicity, assessed using the Common Terminology Criteria for Adverse Events version 4.0. Results Twenty-four patients with 24 lesions (17 abdominal lymph nodes and seven stumps) were treated with SBRT, of which five patients presented with abdominal lymph nodes and synchronous metastases in the liver and lung. The 6-, 12-, and 24-month actuarial local control rates were 95.2%, 83.8%, and 62.1%, respectively. For the entire cohort, the median overall survival from diagnosis and SBRT was 28.9 and 12.2 months, respectively. Symptom alleviation was observed in eleven of 14 patients (78.6%) within a median of 8 days (range, 1–14 days) after SBRT. Nine patients (37.5%) experienced Common Terminology Criteria for Adverse Events version 4.0 grade 1–2 acute toxicities; one patient experienced grade 3 acute toxicity due to thrombocytopenia. Conclusion SBRT is a safe and effective treatment for patients with recurrent pancreatic adenocarcinoma at the abdominal lymph node or stump after surgery. Further studies are needed before SBRT can be recommended routinely.

Stereotactic radiation therapy for oligometastases or oligorecurrence within mediastinal lymph nodes

Aims This study evaluated the safety and efficacy of stereotactic radiation therapy (SRT) for the treatment of patients with oligometastases or oligorecurrence within mediastinal lymph nodes (MLNs) originating from different tumors. Methods Between October 2006 and May 2015, patients with MLN oligometastases or oligorecurrence were enrolled and treated with SRT at our hospital. The primary endpoint was MLN local control (LC). Secondary endpoints were time to symptom alleviation, overall survival (OS) after SRT, and toxicity using the Common Terminology Criteria for Adverse Events (CTCAE v4.0). Results Eighty-five patients with 98 MLN oligometastases or oligorecurrences were treated with SRT. For the entire cohort, the 1-year and 5-year actuarial LC rates were 97% and 77%, respectively. Of 53 symptomatic patients, symptom alleviation was observed in 47 (89%) after a median of 5 days (range, 3-30 days). The median OS was 27.2 months for all patients. For patients with non-small cell lung cancer, univariate and multivariate analyses revealed that a shorter interval between diagnosis of primary tumors and SRT and larger MLN SRT volume were associated with worse OS. CTCAE v4.0 ≥ Grade 3 toxicities occurred in six patients (7%), with Grade 5 in three patients (all with RT history to MLN station 7). Conclusions SRT is a safe and efficacious treatment modality for patients with oligometastases or oligorecurrence to MLNs originating from different tumors, except for patients who received radiotherapy to MLN station 7. Further investigation is warranted to identify the patients who benefit most from this treatment modality.

Multimodality therapy is recommended for limited-stage combined small cell esophageal carcinoma

Background and aim Limited-stage combined small cell esophageal carcinoma (LS-C-SCEC) is a rare, poorly understood, underdiagnosed disease, with components of both small cell esophageal cancer and non–small cell esophageal cancer. We investigated the optimal treatment strategy and prognostic factors in patients with LS-C-SCEC. Patients and methods LS-C-SCEC patients included in the analysis (from our hospital and the literature) were treated between January 1966 and December 2013. Patient treatment strategies included surgery (S), chemotherapy (CT), and radiation therapy (RT). The primary end point was overall survival (OS); the secondary end points included tumor complete response rates, patterns of failure, and toxicity. Kaplan–Meier curves were compared with the log-rank test. Univariate and multivariate analyses were used to determine prognosticators for OS. Results A total of 72 patients were included in the analysis: 24 (33%) from our hospital and 48 (67%) from the literature. The median OS of all patients was 15.0 months. Patients who received CT had a significantly longer median OS than did those who did not (OS 22.8 months vs 10.0 months) (P=0.03). Patients treated with multimodality therapy (including RT+CT [18%], S+CT [40%], or S+RT+CT [17%]) vs monotherapy (typically, S [18%]) had significantly improved OS (15.5 months vs 9.3 months) (P=0.02) and complete response rates. On multivariate analysis, tumor location (upper third of the esophagus) and type of treatment (monotherapy) were the only factors predictive of poor OS. Conclusion Multimodality therapy (including RT+CT, S+CT, or S+RT+CT) improves OS for patients with LS-C-SCEC compared with monotherapy (typically, S). Additional studies are necessary to personalize multimodal treatment approaches to individual patients.

The prognosis factor of adjuvant radiation therapy after surgery in uterine sarcomas.

Objective This retrospective study evaluated the role of adjuvant radiotherapy (AR) after surgery in patients with uterine sarcoma and analyzed the prognostic factors of local-regional failure-free survival (LRFFS) and overall survival (OS). Patients and methods A study of a total of 182 patients with uterine sarcoma was conducted between June 1994 and October 2014. Adjuvant radiotherapy was defined as postoperative external beam radiation to the pelvis (30–50 Gray/10–25 fractions at five fractions/week). The primary end point was LRFFS, and the secondary end point was OS. Kaplan–Meier curves were compared using the log-rank test. Cox regression analyses were used to determine prognosticators for LRFFS and OS. Results The median follow-up time of all patients was 75 months, with a 5-year LRFFS of 62.1%. The 2-year and 5-year LRFFS rates were longer for those who received AR than for those who did not receive AR (83.4% vs 70.3%; 78% vs 55.3%; P=0.013). The 5-year OS of all patients was 56.2%, and no significant differences were observed in the 2-year and 5-year OS rates between these two groups (82.7% vs 71.4%; 64.1% vs 51.7%; P=0.067). Importantly, in patients with leiomyosarcoma, the 2-year and 5-year LRFFS and OS rates were longer for those who received AR than for those who did not receive AR (P=0.04 and P=0.02 for the 2-year and 5-year LRFFS, respectively). Conclusion Patients with uterine sarcoma who were treated with AR after surgery demonstrated an improved LRFFS compared with those who were treated with surgery alone, especially those patients with leiomyosarcoma. Therefore, the role of personalized adjuvant radiation for patients with uterine sarcoma still requires further discussion.