Cytokine-induced killer cells co-cultured with complete tumor antigen-loaded dendritic cells, have enhanced selective cytotoxicity on carboplatin-resistant retinoblastoma cells

Retinoblastoma: Review and new insights

Retinoblastoma (Rb), the most frequent malignant intraocular tumor in childhood, is caused by mutations in the retinoblastoma gene (RB1) situated on chromosome 13q14.2. The incidence of retinoblastoma is approximately 1 in 17,000 live births with approximately 8,000 new cases diagnosed each year worldwide. Rb is the prototypical hereditary cancer in humans. Autosomal dominant inheritance is seen in 30-40% of cases whereas the non-inherited sporadic type accounts for the remaining 60-70%. Rb arises due to inactivation of both alleles of the Rb tumor suppressor gene, which results in a defective Rb protein (pRB) with subsequent cell cycle impairment and uncontrolled cell proliferation. Patients with Rb have survival rates higher than 95-98% in industrialized countries but mortality remains high in developing countries. For example, the mortality rate in Africa is 70%. In all cases of intraocular and extraocular retinoblastoma, there is a need for new therapies that are more effective and carry less risk of toxicity. The Bruckner test is a practical and easy test for the detection of Rb, this test consists of assessing the fundus reflex through the pupil (red reflex) in both eyes simultaneously with a bright coaxial light produced with the direct ophthalmoscope. Rb can be detected by the Bruckner test showing a pupil that shines white or “Leukocoria”. Although the diagnosis of Rb remains essentially clinical, the newly identified biomarkers could contribute to early molecular detection, timely detection of micrometastases and establish new therapeutic options for Rb.

Establishment and Characterization of Carboplatin-Resistant Retinoblastoma Cell Lines

Carboplatin-based chemotherapy is the primary treatment option for the management of retinoblastoma, an intraocular malignant tumor observed in children. The aim of the present study was to establish carboplatin-resistant retinoblastoma cell lines to facilitate future research into the treatment of chemoresistant retinoblastoma. In total, two retinoblastoma cell lines, Y79 and SNUOT-Rb1, were treated with increasing concentrations of carboplatin to develop the carboplatin-resistant retinoblastoma cell lines (termed Y79/CBP and SNUOT-Rb1/CBP, respectively). To verify resistance to carboplatin, the degree of DNA fragmentation and the expression level of cleaved caspase-3 were evaluated in the cells, following carboplatin treatment. In addition, the newly developed carboplatin-resistant retinoblastoma cells formed in vivo intraocular tumors more effectively than their parental cells, even after the intravitreal injection of carboplatin. Interestingly, the proportion of cells in the G0/G1 phase was higher in Y79/CBP and SNUOT-Rb1/CBP cells than in their respective parental cells. In line with these data, the expression levels of cyclin D1 and cyclin D3 were decreased, whereas p18 and p27 expression was increased in the carboplatin-resistant cells. In addition, the expression levels of genes associated with multidrug resistance were increased. Thus, these carboplatin-resistant cell lines may serve as a useful tool in the study of chemoresistance in retinoblastoma and for the development potential therapeutics.

Linoleic and oleic acids enhance cell migration by altering the dynamics of microtubules and the remodeling of the actin cytoskeleton at the leading edge

Fatty acids (FA) have a multitude of biological actions on living cells. A target of their action is cell motility, a process of critical importance during cancer cell dissemination. Here, we studied the effect of unsaturated FA on ovarian cancer cell migration in vitro and its role in regulating cytoskeleton structures that are essential for cell motility. Scratch wound assays on human ovary cancer SKOV-3 cell monolayers revealed that low doses (16 μM) of linoleic acid (LA, 18:2 ω6) and oleic acid (OA; 18:1 ω9) promoted migration, while α-linolenic acid (ALA, 18:3 ω3), showed a migration rate similar to that of the control group. Single cell tracking demonstrated that LA and OA-treated cells migrated faster and were more orientated towards the wound closure than control. In vitro addition of those FA resulted in an increased number, length and protrusion speed of filopodia and also in a prominent and dynamic lamellipodia at the cell leading edge. Using time-lapse video-microscopy and FRAP we observed an increase in both the speed and frequency of actin waves associated with more mobile actin and augmented Rac1 activity. We also observed that FA induced microtubule-organizing center (MTOC)-orientation towards the cell front and affected the dynamics of microtubules (MT) in the direction of cell migration. We propose that environmental cues such as OA and LA present in ascitic fluid, should be taken into account as key factors for the regulation of cell migration.

RPL41 sensitizes retinoblastoma cells to chemotherapeutic drugs via ATF4 degradation

Retinoblastoma is the most common intraocular cancer with metastatic potential affecting infants and children. Although chemotherapy is available for retinoblastoma, side effects and drug resistance are frequent. Rpl41, encoding ribosomal protein L41 (RPL41), has been identified as a tumor suppressor gene, and its targeted degradation of activating transcription factor 4 (ATF4) produces an antitumor effect. The goal of the present study is to provide experimental evidence for the clinical application of a small peptide regimen in combination with chemotherapy for the treatment of retinoblastoma and to investigate the mechanism of their combined cytotoxicity. It was observed that treatment with the RPL41 peptide alone decreased the viability, migration, and invasion of retinoblastoma Y79 and Weri-Rb1 cells, in addition to promoting cell apoptosis and cell cycle arrest. Furthermore, RPL41 protein levels showed a significantly decreased trend in retinoblastoma specimens, whereas ATF4 protein levels tended to be increased. Mechanistically, ATF4 degradation as a result of RPL41 peptide treatment was observed in retinoblastoma Y79 and Weri-Rb1 cells. Most important, low-dose administration of the RPL41 peptide significantly enhanced the antitumor effect of carboplatin, and further analysis confirmed their synergistic effect as anti-retinoblastoma therapy, indicating that RPL41 sensitized Y79 and Weri-Rb1 retinoblastoma cells to carboplatin. Thus, our data provide a preclinical rationale for the exploration of the RPL41 peptide as a potential adjuvant to carboplatin treatment in retinoblastoma.

Development of c‑MET‑specific chimeric antigen receptor‑engineered natural killer cells with cytotoxic effects on human liver cancer HepG2 cells

In recent years, cellular immunotherapy has served an important role in the combined treatment of hepatocellular carcinoma. The possibility of specific cell therapies for the treatment of solid tumours has been further explored following the success of chimeric antigen receptor (CAR)-T cell therapy in the treatment of haematological tumours. The present study aimed to evaluate the specificity and efficiency of c-MET-targeted CAR-NK cell immunotherapy on human liver cancer in vitro. A CAR structure that targeted and recognised a c-MET antigen was constructed. c-MET-CAR was transferred into primary NK cells using lentiviral infection. c-MET-positive HepG2 cells were used as an in vitro study model. The cytotoxicity assay results revealed that c-MET-CAR-NK cells exhibited more specific cytotoxicity for HepG2 cells with high c-MET expression compared with the lung cancer cell line H1299, which has low levels of c-MET expression. The results of the present study demonstrated that c-MET may be a specific and effective target for human liver cancer cell CAR-NK immunotherapy. Based on these results, CAR-NK cell-based immunotherapy may provide a potential biotherapeutic approach for liver cancer treatment in the future.

The antitumor function of arctigenin in human retinoblastoma cells is mediated by jagged‑1

Retinoblastoma is an intraocular malignant tumor that may severely affect vision and represents a life‑threatening disease in children. Arctigenin (ATG) is an active compound that exhibits numerous pharmacological activities, which is isolated from the seeds of greater burdock (Arctium lappa Linnaeus), a plant used in traditional Chinese herbal medicine. The present study aimed to investigate the effects of ATG on cancer progression by analyzing the retinoblastoma cell line Y79. ATG exhibited a significant inhibitory effect on the viability of Y79 cells in a dose‑dependent manner. Furthermore, treatment with ATG promoted apoptosis, and increased the protein expression levels of B‑cell lymphoma 2 (BCL‑2)‑associated X protein and decreased the protein expression levels of BCL‑2. Cell migration was suppressed following treatment with ATG, as assessed by Transwell migration assay. Furthermore, the protein expression levels of jagged‑1 (JAG1) were decreased, and various factors involved in the Notch signaling pathway, including the Notch intracellular domain (NICD), transcription factor HES (HES)5 and HES1 were downregulated following treatment with ATG. The decreased expression levels of JAG1 were restored in response to JAG1 overexpression, alongside increases in the protein expression levels of NICD, HES5 and HES1. Furthermore, overexpression of JAG1 partly restored the cell viability and migration suppressed following treatment with ATG. In addition, ATG‑induced apoptosis was reduced by JAG1 overexpression. Collectively, the present results suggested that ATG may serve as an antitumor compound by suppressing the proliferation and migration of retinoblastoma cells, inducing apoptosis, downregulating the protein expression levels of JAG1, and decreasing the activity of the Notch signaling pathway.

Stimulation of DC-CIK with PADI4 Protein Can Significantly Elevate the Therapeutic Efficiency in Esophageal Cancer

Background

PADI4 has extensive expression in many tumors. This study applied PADI4 as a tumor marker to stimulate DC- (dendritic cell-) CIK (cytokine-induced killer), an immunotherapy approach.

Methods

A PADI4 expression plasmid was transfected into EC-originating ECA-109 cells. PADI4 gene was also inserted into a prokaryotic expression vector to produce recombinant protein. Lysate from PADI4-overexpressing cells or the purified recombinant PADI4 protein was used to load DCs, and the cells were then coincubated with CIK cells. DC and CIK cell phenotypes were determined using flow cytometry. The proliferation and viability of CIK cells were analyzed using trypan blue staining. The cytotoxic effect of DC-CIK cells on cultured ECA-109 cells was determined using CCK8 assays. Tumor-bearing mice were prepared by injection of ECA-109 cells. DC-CIK cells stimulated with lysate from PADI4-overexpressing cells or the PADI4 recombinant protein were injected into the tumor-bearing mice. The tumor growth was measured with magnetic resonance imaging (MRI).

Results

Following incubation with lysate from PADI4-overexpressing cells, the ratio of CD40⁺ DCs increased by 17.5%. Induction of CIK cells with PADI4-stimulated DCs elevated the cell proliferation by 53.2% and the ability of CIK cells to kill ECA-109 cells by 12.1%. DC-CIK cells stimulated with lysate from PADI4-overexpressing cells suppressed tumor volume by 18.6% in the tumor-bearing mice. The recombinant PADI4 protein showed a similar effect on CIK cell proliferation and cytotoxicity as that of the lysate from PADI4-overexpressing cells. Furthermore, the recombinant protein elevated the ratio of CD40⁺ DCs by 111.8%, CD80⁺ DCs by 6.3%, CD83⁺ DCs by 30.8%, and CD86⁺ DCs by 7.8%. Induction of CIK cells with rPADI4-stimulated DCs elevated the cell proliferation by 50.3% and the ability of CIK cells to kill ECA-109 cells by 14.7% and suppressed tumor volume by 35.1% in the animal model.

Conclusion

This study demonstrates that stimulation of DC-CIK cells with PADI4 significantly suppressed tumor growth in tumor-bearing mice by promoting DC maturation, CIK cell proliferation, and cytotoxicity. PADI4 may be a potential tumor marker that could be used to improve the therapeutic efficiency of DC-CIK cells.

The Antitumor Immunity and Tumor Responses of Chemotherapy with or without DC-CIK for Non-Small-Cell Lung Cancer in China: A Meta-Analysis of 28 Randomized Controlled Trials

OBJECTIVE

DC-CIK therapy included DC-CIK cells and Ag-DC-CIK cells. To further confirm whether DC-CIK reconstructs the antitumor immunity and improves the tumor responses and reveals its optimal usage and combination with chemotherapy, we systematically reevaluated all the related studies.

MATERIALS AND METHODS

All studies about DC-CIK plus chemotherapy for NSCLC were collected from the published and ongoing database as CBM, CNKI, VIP, Wanfang, ISI, Embase, MEDLINE, CENTRAL, WHO-ICTRP, Chi-CTR, and US clinical trials (established on June 2017). We evaluated their methodological bias risk according to the Cochrane evaluation handbook of RCTs (5.1.0), extracted data following the predesigned data extraction form, and synthesized the data using meta-analysis.

RESULTS

We included 28 RCTs (phase IV) with 2242 patients, but most trials had unclear bias risk. The SMD and 95% CI of meta-analysis for CD3+ T cells, CD3+ CD4+ T cells, CD3+ CD8+ T cells, CD4+/CD8+ T cell ratio, CIK cells, NK cells, and Treg cells were as follows: 1.85 (1.39 to 2.31), 0.87 (0.65 to 1.10), 1.04 (0.58 to 1.50), 0.75 (0.27 to 1.22), 3.87 (2.48 to 5.25), 1.51 (0.99 to 2.03), and -2.31(-3.84 to -0.79). The RR and 95% CI of meta-analysis for ORR and DCR were as follows: 1.38 (1.24 to 1.54) and 1.27 (1.20 to 1.34). All differences were statistically significant between DC-CIK plus chemotherapy and chemotherapy alone. Subgroup analysis showed that only DC-CIK cells could increase the CD3+T cells, CD3+ CD4+T cells, CD3+ CD8+T cells, and CD4+/CD8+ T cell ratio. In treatment with one cycle or two cycles and combination with NP or GP, DC-CIK could increase the CD4+/CD8+ T cell ratio. All results had good stability.

CONCLUSIONS

DC-CIK therapy can simultaneously improve the antitumor immunity and tumor responses. DC-CIK therapy, especially DC-CIK cells, can improve antitumor immunity through increasing the T lymphocyte subsets, CIK cell, and NK cells in peripheral blood. The one cycle to two cycles may be optimal cycle, and the NP or GP may be optimal combination.

Co-culture of dendritic cells and cytokine-induced killer cells effectively suppresses liver cancer stem cell growth by inhibiting pathways in the immune system

BACKGROUND

Application of dendritic cells (DC) for cancer immunotherapy involves tumor-associated immunogenic antigens for effective therapeutic strategies. The present study investigated whether DC co-cultured with autologous cytokine-induced killer cells (CIK) could induce a more specific immune response against liver cancer stem cells (LCSC) generated from human hepatocellular carcinoma (HCC) cells in vitro and in vivo.

METHODS

Human DC and CIK were generated from peripheral blood mononuclear cells (PBMCs) taken from consenting liver cancer patients. Flow cytometry was used to determine the phenotypes of DC and CIK, and cell proliferation. The tumor growth and anti-tumor activity of these cells were further evaluated using a nude mouse tumor model.

RESULTS

We demonstrated that DC and CIK significantly enhanced the apoptosis ratio, depending on DC-CIK cell numbers, by increasing caspase-3 protein expression and reducing proliferating cell nuclear antigen (PCNA) protein expression against LCSC. The in vivo data indicated that DC-CIK exhibited significant LCSC cell-induced tumor growth inhibition in nude mice, which was most significant with LCSC antigen loaded DCs.

CONCLUSIONS

The results showed, that DC-CIK cells could inhibit HCC and LCSC growths in vitro and in vivo and the most successful DC triggering of cell cytotoxic activity could be achieved by their LCSC antigen loading.

SYK-targeted dendritic cell-mediated cytotoxic T lymphocytes enhance the effect of immunotherapy on retinoblastoma

PURPOSE

Retinoblastoma (RB) is the most common primary intraocular tumor in children. Chemotherapy is currently the main method of RB treatment. Unfortunately, RB often becomes chemoresistant and turns lethal. Here, we used in vitro cell immunotherapy to explore whether adoptive immunotherapy could be used as a potential treatment for RB. We focused on spleen tyrosine kinase (SYK), which is significantly upregulated in RB cells and serves as a marker for RB cells.

METHODS

Using lentiviruses, we genetically modified dendritic cells (DCs) to express and present the SYK peptide antigen to cytotoxic T lymphocytes (CTLs) in vitro. We used SYK-negative cell lines (MDA-MB-231, MCF-10A, and hTERT-RPE1) and SYK-positive cell lines (MCF-7 and RB-Y79) to evaluate the specificity and cytotoxicity of DC presented CTLs using FACS, live-cell imaging, and RNA interference.

RESULTS

The cytotoxicity of CTLs induced by SYK-overexpressing DCs (SYK-DC-CTLs) was enhanced more than three times in SYK-positive cell lines compared with SYK-negative cell lines. DCs primed with SYK could drive CTL cytotoxicity against SYK-positive cell lines but not against SYK-negative cell lines. Moreover, SYK-silenced RB-Y79 cells successfully evaded the cytotoxic attack from SYK-DC-CTLs. However, SYK-DC-CTLs could target SYK overexpressed hTERT-RPE1 cells, suggesting that SYK is a specific antigen for RB. Furthermore, SYK-DC-CTL exhibited specific cytotoxicity against carboplatin-resistant RB-Y79 cells in vitro.

CONCLUSIONS

Our data showed that SYK could be a potential immunotherapy target mediated by DCs. We propose SYK as a candidate target for treatment of chemoresistant RB.

Innovative Clinical Perspectives for CIK Cells in Cancer Patients

Cytokine-induced killer (CIK) cells are T lymphocytes that have acquired, in vitro, following extensive manipulation by Interferon gamma (IFN-γ), OKT3 and Interleukin 2 (IL-2) addition, the expression of several Natural Killer (NK) cell-surface markers. CIK cells have a dual "nature", due to the presence of functional TCR as well as NK molecules, even if the antitumoral activity can be traced back only to the NK-like structures (DNAM-1, NKG2D, NKp30 and CD56). In addition to antineoplastic activity in vitro and in several in-vivo models, CIK cells show very limited, if any, GvHD toxicity as well as a strong intratumoral homing. For all such reasons, CIK cells have been proposed and tested in many clinical trials in cancer patients both in autologous and allogeneic combinations, up to haploidentical mismatching. Indeed, genetic modification of CIK cells as well as the possibility of combining them with specific monoclonal antibodies will further expand the possibility of their clinical utilization.

Characterization and functional analysis of a slow-cycling subpopulation in colorectal cancer enriched by cell cycle inducer combined chemotherapy

The concept of cancer stem cells has been proposed in various malignancies including colorectal cancer. Recent studies show direct evidence for quiescence slow-cycling cells playing a role in cancer stem cells. There exists an urgent need to isolate and better characterize these slow-cycling cells. In this study, we developed a new model to enrich slow-cycling tumor cells using cell-cycle inducer combined with cell cycle-dependent chemotherapy in vitro and in vivo. Our results show that Short-term exposure of colorectal cancer cells to chemotherapy combined with cell-cycle inducer enriches for a cell-cycle quiescent tumor cell population. Specifically, these slow-cycling tumor cells exhibit increased chemotherapy resistance in vitro and tumorigenicity in vivo. Notably, these cells are stem-cell like and participate in metastatic dormancy. Further exploration indicates that slow-cycling colorectal cancer cells in our model are less sensitive to cytokine-induced-killer cell mediated cytotoxic killing in vivo and in vitro. Collectively, our cell cycle inducer combined chemotherapy exposure model enriches for a slow-cycling, dormant, chemo-resistant tumor cell sub-population that are resistant to cytokine induced killer cell based immunotherapy. Studying unique signaling pathways in dormant tumor cells enriched by cell cycle inducer combined chemotherapy treatment is expected to identify novel therapeutic targets for preventing tumor recurrence.

Influence of the number and interval of treatment cycles on cytokine-induced killer cells and their adjuvant therapeutic effects in advanced non-small-cell lung cancer (NSCLC)

OBJECTIVE

Cytokine-induced killer (CIK) cells have important therapeutic effects in adoptive cell transfer (ACT) for the treatment of various malignancies. In this study, we focused on in vitro expansion of CIK cells and their clinical efficacy in combination with chemotherapy in patients with advanced non-small-cell lung cancer (NSCLC).

METHODS

A total of 64 patients with NSCLC (enrolled from 2011 to 2012), including 32 patients who received chemotherapy alone or with sequential radiotherapy (conventional treatment, control group) and 32 patients who received conventional treatment and sequential CIK infusion (study group), were retrospectively analyzed. The time to progression (TTP), overall survival (OS) and adverse effects were analyzed and the phenotype of lymphocytes in CIK population was also determined by flow cytometry.

RESULTS

After in vitro expansion, the average percentage of CIK cells was 26.35%. During the 54-month follow up, the median OS and TTP were significantly longer in the study group than in the control group (P=0.0189 and P=0.0129, respectively). The median OS of the ACT≥4cycles subgroup was significantly longer than that of the ACT<4cycles subgroup (P=0.0316). The percentage of CIK cells in patients who received ≥4cycles of ACT was higher than that in patients treated with <4cycles of ACT (P=0.0376). Notably, CIK cells were difficult to expand in vitro in some patients after the first ACT cycle but became much easier as the treatment cycles increased monthly. Longer treatment interval negatively impacted the expansion of CIK cells.

CONCLUSIONS

Systematic immune levels can be increasingly boosted by reinfusion of ACT. Conventional treatment plus CIK cells is an effective therapeutic strategy to prevent progression and prolong survival of patients with advanced NSCLC.

Cytokine-Induced Killer Cells As Pharmacological Tools for Cancer Immunotherapy

Cytokine-induced killer (CIK) cells are a heterogeneous population of effector CD3⁺CD56⁺ natural killer T cells, which can be easily expanded in vitro from peripheral blood mononuclear cells. CIK cells work as pharmacological tools for cancer immunotherapy as they exhibit MHC-unrestricted, safe, and effective antitumor activity. Much effort has been made to improve CIK cells cytotoxicity and treatments of CIK cells combined with other antitumor therapies are applied. This review summarizes some strategies, including the combination of CIK with additional cytokines, dendritic cells, check point inhibitors, antibodies, chemotherapeutic agents, nanomedicines, and engineering CIK cells with a chimeric antigen receptor. Furthermore, we briefly sum up the clinical trials on CIK cells and compare the effect of clinical CIK therapy with other immunotherapies. Finally, further research is needed to clarify the pharmacological mechanism of CIK and provide evidence to formulate uniform culturing criteria for CIK expansion.

Efficient killing of radioresistant breast cancer cells by cytokine-induced killer cells

Recurrence of breast cancer after radiotherapy may be partly explained by the presence of radioresistant cells. Thus, it would be desirable to develop an effective therapy against radioresistant cells. In this study, we demonstrated the intense antitumor activity of cytokine-induced killer cells against MCF-7 and radioresistant MCF-7 cells, as revealed by cytokine-induced killer-mediated cytotoxicity, tumor cell proliferation, and tumor invasion. Radioresistant MCF-7 cells were more susceptible to cytokine-induced killer cell killing. The stronger cytotoxicity of cytokine-induced killer cells against radioresistant MCF-7 cells was dependent on the expression of major histocompatibility complex class I polypeptide-related sequence A/B on radioresistant MCF-7 cells after exposure of cytokine-induced killer cells to sensitized targets. In addition, we demonstrated that cytokine-induced killer cell treatment sensitized breast cancer cells to chemotherapy via the downregulation of TK1, TYMS, and MDR1. These results indicate that cytokine-induced killer cell treatment in combination with radiotherapy and/or chemotherapy may induce synergistic antitumor activities and represent a novel strategy for breast cancer.

Cytokine-induced killer cells interact with tumor lysate-pulsed dendritic cells via CCR5 signaling

The antitumor activity of cytokine-induced killer (CIK) cells can be increased by co-culturing them with tumor lysate-pulsed dendritic cells (tDCs); this phenomenon has been studied mainly at the population level. Using time-lapse imaging, we examined how CIK cells gather information from tDCs at the single-cell level. tDCs highly expressed CCL5, which bound CCR5 expressed on CIK cells. tDCs strongly induced migration of Ccr5(+/+) CIK cells, but not that of Ccr5(-/-) CIK cells or Ccr5(+/+) CIK cells treated with the CCR5 antagonist Maraviroc. Individual tDCs contacted Ccr5(+/+) CIK cells more frequently and lengthily than with Ccr5(-/-) CIK cells. Consequently, tDCs increased the antitumor activity of Ccr5(+/+) CIK cells in vitro and in vivo, but did not increase that of Ccr5(-/-) CIK cells. Taken together, our data provide insight into the mechanism of CIK cell activation by tDCs at the single-cell level.

Enhanced specific antitumor immunity of dendritic cells transduced with the glypican 3 gene and co-cultured with cytokine-induced killer cells against hepatocellular carcinoma cells

Dendritic cell (DC)‑based cancer immunotherapy requires an immunogenic tumor‑associated antigen and an effective therapeutic strategy. Glypican 3 (GPC3) is a valuable diagnostic marker and a potential therapeutic target in hepatocellular carcinoma (HCC). The present study investigated whether DCs transduced with the GPC3 gene (DCs‑GPC3) and co‑cultured with autologous cytokine‑induced killer cells (CIKs) may induce a marked specific immune response against GPC3‑expressing HCC cells in vitro and in vivo. Human DCs were transfected with a green fluorescent protein plasmid with GPC3 by nucleofection and then co‑cultured with autologous CIKs. Flow cytometry was used to measure the phenotypes of DCs and CIKs. The co‑cultured cells were harvested and incubated with HCC cells and the cytotoxicity of the CIKs was assessed by nonradioactive cytotoxicity assay. The anti-tumor activity of these effector cells was further evaluated using a nude mouse tumor model. The results demonstrated that DCs‑GPC3 significantly promoted the autologous CIKs differentiation, as well as anti‑tumor cytokine interferon‑γ secretion. In addition, DCs‑GPC3‑CIKs significantly enhanced the cytotoxic activity against GPC3‑expressing HepG2 cells, indicating a GPC3‑specific marked immune response against HCC cells. The in vivo data indicated that DCs‑GPC3‑CIKs exhibited significant HepG2 cell‑induced tumor growth inhibition in nude mice. The results of the present study provided a new insight into the design of personalizing adoptive immunotherapy for GPC3‑expressing HCC cells.

A killer choice for cancer immunotherapy

The promise of cell-based immunotherapies for the treatment of cancer offers the potential of therapeutic synergy with chemo- and radiotherapies that may overcome current limitations leading to durable responses and prevention of recurrence. There is a wide array of cell-based immunotherapies that are either poised to enter cancer clinical trials or are in clinical trials, and many are showing some success. Yet within this field, there are clear obstacles that need to be overcome, including limited access across tissue barriers, development of antigen tolerance, and the immunosuppressive microenvironment of tumors. Through an understanding of immune cell signaling and trafficking, immune cell populations can be selected for adoptive transfer, and delivery strategies can be developed that circumvent these obstacles to effectively direct populations of cells with robust anti-tumor efficacy to the target. Within the realm of immune cell therapies, cytokine-induced killer (CIK) cells have demonstrated promising trafficking patterns, effective delivery of synergistic therapeutics, and stand-alone efficacy. Here, we discuss the next generation of CIK therapies and their application for the effective treatment of a wide variety of cancers.

Phenotypic and functional characterization of cytokine-induced killer cells derived from preterm and term infant cord blood

Cord blood has gradually become an important source for hematopoietic stem cell transplantation (HSCT) in the human, particularly in pediatric patients. Adoptive cellular immunotherapy of patients with hematologic malignancies after umbilical cord blood transplant is crucial. Cytokine‑induced killer (CIK) cells derived from cord blood are a new type of antitumor immune effector cells in tumor prevention and treatment and have increasingly attracted the attention of researchers. On the other hand, it has been suggested that preterm infant cord blood retains an early differentiation phenotype suitable for immunotherapy. Therefore, we determined the phenotypic and functional characterization of CIK cells derived from preterm infant cord blood (PCB-CIK) compared with CIK cells from term infant cord blood (TCB-CIK). Twenty cord blood samples were collected and classified into two groups based on gestational age. Cord blood mononuclear cells (CBMCs) were isolated, cultured and induced to CIK cells in vitro. We used flow cytometry to detect cell surface markers, FlowJo software to analyze the proliferation profile and intracellular staining to test the secretion of cytokines. Finally, we evaluated the antitumor activity of CIK cells against K562 in vitro. Compared with TCB-CIK, PCB-CIK cells demonstrated faster proliferation and higher expression of activated cell surface markers. The secretion of IL-10 was lower in PCB-CIK cells while the expression of perforin and CD107a had no significant difference between the two cell groups. PCB-CIK cells exhibited a high proliferation rate while the cytotoxic activity had no difference between the PCB-CIK and TCB-CIK cells. Hence preterm infant cord blood may be a potential source for immunotherapy.

An update on new adoptive immunotherapy strategies for solid tumors with cytokine-induced killer cells

INTRODUCTION

Cytokine-induced killer (CIK) cells are mainly CD3(+)CD56(+) NKT cells exhibiting non-MHC-restricted cytotoxicity against a broad range of tumors. Much research is going on to improve CIK cell effectivity and to evaluate the clinical benefit of different combinations with conventional therapies.

AREAS COVERED

This review provides an update on in vitro/in vivo studies and clinical trials applying CIK cells for the treatment of solid tumors. This comprises attempts using additional cytokines, genetic engineering and combinations with different conventional and modern therapies.

EXPERT OPINION

Since our last review, much effort has been made to improve CIK cell cytotoxicity and clinical effectivity. Targeted CIK cell therapy and combinations of CIK cells with antiangiogenic drugs or oncolytic viruses are examples of recent outstanding achievements in the field of adoptive CIK cell therapy. The clinical application of CIK cells in combination with conventional therapies, especially, obtained promising results. However, the best combination and the optimal therapy schedule have yet to be defined.

Optimized treatment with RF thermotherapy and immunotherapy combined with CyberKnife for advanced high-risk tumors: A clinical trial report

This study was conducted to evaluate the application value of optimized treatment with radiofrequency (RF) thermotherapy and immunotherapy combined with CyberKnife for advanced high-risk tumors. The database of 1,013 patients with 2,136 tumor lesions and 1,237 target areas who underwent treatment with CyberKnife between November, 2010 and November, 2012, was retrospectively reviewed. We randomly assigned 505 eligible patients (observation group) to RF thermotherapy and adoptive immunotherapy with cytokine-induced killer cells and the remaining 508 patients (control group) to no adjuvant treatment. The patients in the two groups were recorded on efficacy assessment according to imageological examination, World Health Organization criteria, Karnofsky performance status, or radioimmunoassay (RIA) detection. The effective rate of the observation group was 75.05%, whereas that of the control group was 58.06% (P<0.05). The results revealed that CyberKnife combined with hyperthermia and biological therapy are highly effective in improving the local tumor control rate. Further analysis of the Karnofsky score and RIA detection confirmed that this type of combination therapy significantly improved the quality of life. The optimized treatment of RF thermotherapy and immunotherapy combined with CyberKnife may act synergistically in eliminating tumor cells, confirming the efficacy of this type of treatment for patients with advanced malignant tumors.