Effect of Endostatin on Preventing Postoperative Progression of Distant Metastasis in a Murine Lung Cancer Model

Tumor refractoriness to endostatin anti-angiogenesis is associated with the recruitment of CD11b+Gr1+ myeloid cells and inflammatory cytokines

Aims and background

A major challenge in developing antiangiogenic therapies is tumor intrinsic refractoriness and the emergence of treatment-induced resistance. Recently, such resistance is considered to be associated with inflammatory changes in the tumor microenvironment. However, no information has been acquired about the effect of endostatin on tumor microenvironment in this field. We established two tumor models refractory to endostatin treatment and sought to determine the role of inflammatory changes in the development of tumor refractoriness to antiangiogenic therapy.

Methods

Three xenograft tumor murine models were treated with low-dose endostatin or high-dose endostatin for 10 days. The effect of endostatin on tumor growth was observed, and tumors refractory to endostatin treatment were defined. Flow cytometry were carried out to assess the presence of CD11b+Gr1+ myeloid cells in the peripheral blood and in the tumor. Inflammatory cytokine levels in peripheral blood were measured using the enzyme-linked immunosorbent assay. The expression of NF-κB, versican and hypoxia-inducible factor-1α in the tumor was evaluated using immunohistochemistry.

Results

LLC and B16F1 tumors were defined as animal models of refractoriness to endostatin treatment. CD11b+Gr1+ myeloid cells were inherently recruited into the peripheral blood and the tumor microenvironment in the LLC tumor-bearing mice, and levels of serum G-CSF and TNF-α were increased along with the progression of tumor growth. In the B16F1 tumor-bearing mice, CD11b+Gr1+ myeloid cells were acquiredly recruited by endostatin into the peripheral blood and the tumor microenvironment. Additionally, high levels of G-CSF and TNF-α in serum and high expression of NF-κB, versican and hypoxia-inducible factor-1α in tumor tissue were found in B16F1 tumor-bearing mice after endostatin administration.

Conclusions

A tumor can grow inherently or acquiredly with refractoriness to endostatin treatment in vivo. Recruitment of CD11b+Gr1+ myeloid cells and inflammatory cytokines may play an important role in the development of tumor refractoriness to endostatin anti-angiogenesis.

Effects of surgery and anesthetic choice on immunosuppression and cancer recurrence

Background

The relationship between surgery and anesthetic-induced immunosuppression and cancer recurrence remains unresolved. Surgery and anesthesia stimulate the hypothalamic–pituitary–adrenal (HPA) axis and sympathetic nervous system (SNS) to cause immunosuppression through several tumor-derived soluble factors. The potential impact of surgery and anesthesia on cancer recurrence was reviewed to provide guidance for cancer surgical treatment.

Methods

PubMed was searched up to December 31, 2016 using search terms such as, “anesthetic technique and cancer recurrence,” “regional anesthesia and cancer recurrence,” “local anesthesia and cancer recurrence,” “anesthetic technique and immunosuppression,” and “anesthetic technique and oncologic surgery.”

Results

Surgery-induced stress responses and surgical manipulation enhance tumor metastasis via release of angiogenic factors and suppression of natural killer (NK) cells and cell-mediated immunity. Intravenous agents such as ketamine and thiopental suppress NK cell activity, whereas propofol does not. Ketamine induces T-lymphocyte apoptosis but midazolam does not affect cytotoxic T-lymphocytes. Volatile anesthetics suppress NK cell activity, induce T-lymphocyte apoptosis, and enhance angiogenesis through hypoxia inducible factor-1α (HIF-1α) activity. Opioids suppress NK cell activity and increase regulatory T cells.

Conclusion

Local anesthetics such as lidocaine increase NK cell activity. Anesthetics such as propofol and locoregional anesthesia, which decrease surgery-induced neuroendocrine responses through HPA-axis and SNS suppression, may cause less immunosuppression and recurrence of certain types of cancer compared to volatile anesthetics and opioids.

Antiangiogenic therapy using endostatin increases the number of ALDH+ lung cancer stem cells by generating intratumor hypoxia

Antiangiogenic therapy is becoming a promising option for cancer treatment. However, many investigations have recently indicated that these therapies may have limited efficacy, and the cancers in most patients eventually develop resistance to these therapies. There is considerable recently acquired evidence for an association of such resistance with cancer stem-like cells (CSLCs). Here, we used xenograft tumor murine models to further suggest that antiangiogenic agents actually increase the invasive and metastatic properties of lung cancer cells. In our experiments with murine lung cancer xenografts, we found that the antiangiogenic agent endostatin increased the population of ALDH+ cells, and did so by generating intratumoral hypoxia in the xenografts. We further showed endostatin to cause an increase in the CSLC population by accelerating the generation of tumor hypoxia and by recruiting TAMs, MDSCs and Treg cells, which are inflammatory and immunosuppressive cells and which can secrete cytokines and growth factors such as IL-6, EGF, and TGF-β into the tumor microenvironment. All these factors are related with increased CSLC population in tumors. These results imply that improving the clinical efficacy of antiangiogenic treatments will require the concurrent use of CSLC-targeting agents.

Hypoxia and TGF-β1 lead to endostatin resistance by cooperatively increasing cancer stem cells in A549 transplantation tumors

BACKGROUND

Lung cancer is the leading cause of cancer-related deaths worldwide, and treatments for lung cancer have a high failure rate. Anti-angiogenic therapy is also often ineffective because of refractory disease. Endostatin (ES) is one of the most widely-used anti-angiogenic drugs for lung cancer in China, and resistance to it is a barrier that needs to be resolved. It has been shown that myeloid-derived suppressor cells (MDSCs) are involved in resistance to ES. Whether other cells and/or cell factors in the tumor microenvironment that have been shown to be related to resistance to other anti-cancer drugs are also involved in ES resistance is unknown.

RESULTS

In this study, we showed that after continuously treatment with ES for 12 days, volumes of A549 transplantation tumors of mice reached the sizes of tumors which were borne by mice that were treated with normal saline and this meant that resistance to ES appeared. Cancer stem cells (CSCs), which have been widely accepted as one of reasons responsible for resistance to many anti-tumor drugs were also being discovered increased proportionally in A549 transplantation tumors after ES treatment for 12 days. During further exploration of reasons for this increase, we discovered that after ES treatment, microvessel density and vascular endothelial growth factor level was decreased in tumors, whereas transforming growth factor (TGF)-β1 level was elevated, and MDSCs, one of the sources of TGF-β1, were also increased. We speculate that hypoxia and TGF-β1 are responsible for the increased CSC number in A549 transplantation tumors. By using cobalt chloride to mimic hypoxia and human recombinant TGF-β1 in vitro, we found that hypoxia and TGF-β1can indeed enhance the stemness of A549 cells. In addition, the inductive effect of hypoxia is stronger than TGF-β1, and the combination of both is stronger than either alone, which is first report of such a finding, to our knowledge.

CONCLUSIONS

Increased TGF-β1 and strengthened hypoxia in A549 transplantation tumors, as a result of ES therapy, cooperatively increase proportion of CSCs that are involved in ES resistance which was revealed by failure of tumor volume repression after continuously treatment with ES for 12 days.

Versican silencing improves the antitumor efficacy of endostatin by alleviating its induced inflammatory and immunosuppressive changes in the tumor microenvironment

The systematic application of antiangiogenic therapy remains an issue of concern, mainly due to the hypoxic and inflammatory changes in the tumor microenvironment elicited by antiangiogenic therapy. Versican, a 'bridge' connecting inflammation with tumor progression as well as playing a central role in the generation of an inflammatory tumor microenvironment is a promising candidate for the intervention of inflammatory changes in the tumor microenvironment elicited by antiangiogenic therapy. To examine this hypothesis, a short-hairpin RNA targeting versican (shVCAN) was designed and shVCAN stable-transfected B16F1 and Lewis lung carcinoma (LLC) cell lines were established. Simultaneously, the established B16F1 and LLC tumor models were used to investigate the effect of versican silencing on the tumor burden of mice. The results showed that, versican silencing exerted an inhibitory effect on the proliferative and migratory ability of B16F1 cells, but did not affect LLC cells. Endostatin exhibited modest inhibition of tumor growth in tumor-bearing mice. Versican silencing alone effectively suppressed orthotopic tumor growth and significantly prolonged survival time of mice more effectively when combined with endostatin. Endostatin elicited inflammatory and immunosuppressive changes in the tumor microenvironment, including an accumulation of myeloid-derived suppressor cells (MDSCs), tumor-associated macrophages (TAMs) and inflammatory cytokines. In addition, NF-κB and HIF-1α were overexpressed in the tumor. Versican silencing improved the antitumor efficacy of endostatin by alleviating its induced changes in the tumor microenvironment. Thus, versican silencing in the tumor microenvironment offers a promising approach to reverse the tumor refractoriness to antiangiogenic therapies.

Enhanced recovery after surgery protocols for open hepatectomy--physiology, immunomodulation, and implementation

There has been recent interest in enhanced-recovery after surgery (ERAS®) or "fast-track" perioperative protocols in the surgical community. The subspecialty field of colorectal surgery has been the leading adopter of ERAS protocols, with less data available regarding its adoption in hepato-pancreato-biliary surgery. This review focuses on available data pertaining to the application of ERAS to open hepatectomy. We focus on four fundamental variables that impact normal physiology and exacerbate perioperative inflammation: (1) the stress of laparotomy, (2) the use of opioids, (3) blood loss and blood product transfusions, and (4) perioperative fasting. The attenuation of these inflammatory stressors is largely responsible for the improvements in perioperative outcomes due to the implementation of ERAS-based pathways. Collectively, the data suggest that the implementation of ERAS principles should be strongly considered in all patients undergoing hepatectomy.

Does regional anaesthesia and analgesia or opioid analgesia influence recurrence after primary cancer surgery? An update of available evidence

Cancer continues to be a key cause of morbidity and mortality worldwide and its overall incidence continues to increase. Anaesthetists are increasingly faced with the challenge of managing cancer patients, for surgical resection to debulk or excise the primary tumour, or for surgical emergencies in patients on chemotherapy or for the analgesic management of disease- or treatment-related chronic pain. Metastatic recurrence is a concern. Surgery and a number of perioperative factors are suspected to accelerate tumour growth and potentially increase the risk of metastatic recurrence. Retrospective analyses have suggested an association between anaesthetic technique and cancer outcomes, and anaesthetists have sought to ameliorate the consequences of surgical trauma and minimise the impact of anaesthetic interventions. Just how anaesthesia and analgesia impact cancer recurrence and consequent survival is very topical, as understanding the potential mechanisms and interactions has an impact on the anaesthetist's ability to contribute to the successful outcome of oncological interventions. The outcome of ongoing, prospective, randomized trials are awaited with interest.

Vascular endothelial growth factor as a biomarker for endostatin gene therapy

Renal cell carcinoma (RCC) is characterized by high vascular endothelial growth factor (VEGF) production and, consequently, excessive angiogenesis. Several strategies have been developed to target angiogenesis as a method for treating metastatic RCC (mRCC). Endostatin (ES) is a C-terminal fragment of collagen XVIII that has antiangiogenic activity. The aim of this study was to investigate the predictive value of circulating VEGF-A in a murine model of mRCC after ES gene therapy. ES therapy did not affect the levels of collagen XVIII/ES or ES in the tissue. The circulating level of ES was increased in the control and ES-treated groups (normal vs. control, P<0.05 and ES-treated vs. control, P<0.001), and the intratumoral vessels were significantly decreased (ES-treated vs. control, P<0.05). ES therapy decreased the VEGF mRNA levels. The tissue and circulating levels of VEGF in the control group were significantly higher than normal (P<0.01 and P<0.05, respectively). Treatment with ES significantly reduced the VEGF concentrations in both compartments (P<0.001 for tissue and P<0.05 for plasma). Our findings indicate that in addition to the directly targeted tumor vessels, ES exerts its antitumor effect by down-regulating VEGF gene expression in renal tumor cells. Additionally, our findings point to the predictive value of VEGF for ES therapy.

Can anaesthetic and analgesic techniques affect cancer recurrence or metastasis?

Cancer is a leading cause of morbidity and mortality worldwide and the ratio of incidence is increasing. Mortality usually results from recurrence or metastases. Surgical removal of the primary tumour is the mainstay of treatment, but this is associated with inadvertent dispersal of neoplastic cells into the blood and lymphatic systems. The fate of the dispersed cells depends on the balance of perioperative factors promoting tumour survival and growth (including surgery per se, many anaesthetics per se, acute postoperative pain, and opioid analgesics) together with the perioperative immune status of the patient. Available evidence from experimental cell culture and live animal data on these factors are summarized, together with clinical evidence from retrospective studies. Taken together, current data are sufficient only to generate a hypothesis that an anaesthetic technique during primary cancer surgery could affect recurrence or metastases, but a causal link can only be proved by prospective, randomized, clinical trials. Many are ongoing, but definitive results might not emerge for a further 5 yr or longer. Meanwhile, there is no hard evidence to support altering anaesthetic technique in cancer patients, pending the outcome of the ongoing clinical trials.