Increased expression after X-irradiation of MUC1 in cultured human colon carcinoma HT-29 cells

Prospects of Synergy: Local Interventions and CAR T Cell Therapy in Solid Tumors

Chimeric antigen receptor T cell therapy has been established in the treatment of various B cell malignancies. However, translating this therapeutic effect to treat solid tumors has been challenging because of their inter-tumoral as well as intratumoral heterogeneity and immunosuppressive microenvironment. Local interventions, such as surgery, radiotherapy, local ablation, and locoregional drug delivery, can enhance chimeric antigen receptor T cell therapy in solid tumors by improving tumor infiltration and reducing systemic toxicities. Additionally, ablation and radiotherapy have proven to (re-)activate systemic immune responses via abscopal effects and reprogram the tumor microenvironment on a physical, cellular, and chemical level. This review highlights the potential synergy of the combined approaches to overcome barriers of chimeric antigen receptor T cell therapy and summarizes recent studies that may pave the way for new treatment regimens.

CAR T cell-based immunotherapy and radiation therapy: potential, promises and risks

CAR T cell-based therapies have revolutionized the treatment of hematological malignancies such as leukemia and lymphoma within the last years. In contrast to the success in hematological cancers, the treatment of solid tumors with CAR T cells is still a major challenge in the field and attempts to overcome these hurdles have not been successful yet. Radiation therapy is used for management of various malignancies for decades and its therapeutic role ranges from local therapy to a priming agent in cancer immunotherapy. Combinations of radiation with immune checkpoint inhibitors have already proven successful in clinical trials. Therefore, a combination of radiation therapy may have the potential to overcome the current limitations of CAR T cell therapy in solid tumor entities. So far, only limited research was conducted in the area of CAR T cells and radiation. In this review we will discuss the potential and risks of such a combination in the treatment of cancer patients.

LINC01004-SPI1 axis-activated SIGLEC9 in tumor-associated macrophages induces radioresistance and the formation of immunosuppressive tumor microenvironment in esophageal squamous cell carcinoma

Radioresistance and immunosuppression remain the major obstacles in the anti-cancer treatments. This work studies the functions of sialic acid binding Ig like lectin 9 (SIGLEC9) and its related molecules in radioresistance and immunosuppression in esophageal squamous cell carcinoma (ESCC). The single-cell analysis showed that SIGLEC9 was mainly expressed on tumor-associated macrophages (TAMs). Monocytes-derived macrophages were co-cultured with ESCC cells and subjected to radiotherapy. High or low doses of radiotherapy induced SIGLEC9 upregulation and M2 polarization of TAMs. Artificial inhibition of SIGLEC9 in TAMs suppressed the radioresistance and immunosuppressive tumor microenvironment (TME) in the co-cultured ESCC cells. Upstream molecules of SIGLEC9 were predicted via bioinformatics. LINC01004 recruited Spi-1 proto-oncogene (SPI1) in nucleus of TAMs to induce transcriptional activation of SIGLEC9. SIGLEC9 interacted with mucin 1 (MUC1). MUC1 overexpression in ESCCs induced M2 skewing of TAMs, enhanced radioresistance and immunosuppression, and promoted nuclear translocation of β-catenin to suppress radiotherapy-induced ferroptosis of ESCC cells. These effects were blocked upon SIGLEC9 suppression. In vitro results were reproduced in the animal models with xenograft tumors. Taken together, this study demonstrates that the LINC01004-SPI1 axis-activated SIGLEC9 in TAMs induces radioresistance and the formation of immunosuppressive TME in ESCC.

MUC1 confers radioresistance in head and neck squamous cell carcinoma (HNSCC) cells

Mucin 1 (MUC1), a transmembrane glycoprotein, has shown to be as the possible prognostic marker to predict the risk of aggressive head and neck squamous cell carcinoma (HNSCC). In the present study, we investigated the effect of MUC1 in HNSCC cells and the response to X-ray irradiation (IR). Here, we examined the impact of MUC1 overexpression or downexpression on clonogenic survival and apoptosis in response to X-ray irradiation (IR). Radioresistance and radiosensitivity were also observed in HNSCC cells that are MUC1 overexpression and MUC1 downexpression. This enhanced resistance to IR in MUC1-overexpressing cells is primarily due to increased the number of radiation-induced γH2AX/53BP1-positive foci and DNA double-strand break (DSB) repair kinetics. MUC1 overexpression repaired more than 90% of DSBs after 2 Gy radiation by 24 h compared to the empty vector overexpressing cells with less than 50% of DSB repair. However, MUC1 downexpression repaired less than 20% of DSBs compared to the empty vector-overexpresing cells. MUC1 overexpression inhibited proapoptotic protein expression, such as caspase-3, caspase-8, and caspase-9, and induced antiapoptotic protein Bcl-2, followed by resistance to IR-induced apoptosis. Our results showed that targeting MUC1 may be as a promising strategy to counteract radiation resistance of HNSCC cells.

Candidate protein biodosimeters of human exposure to ionizing radiation

PURPOSE

To conduct a literature review of candidate protein biomarkers for individual radiation biodosimetry of exposure to ionizing radiation.

MATERIALS AND METHODS

Reviewed approximately 300 publications (1973 - April 2006) that reported protein effects in mammalian systems after either in vivo or in vitro radiation exposure.

RESULTS

We found 261 radiation-responsive proteins including 173 human proteins. Most of the studies used high doses of ionizing radiation (>4 Gy) and had no information on dose- or time-responses. The majority of the proteins showed increased amounts or changes in phosphorylation states within 24 h after exposure (range: 1.5- to 10-fold). Of the 47 proteins that are responsive at doses of 1 Gy and below, 6 showed phosphorylation changes at doses below 10 cGy. Proteins were assigned to 9 groups based on consistency of response across species, dose- and time-response information and known role in the radiation damage response.

CONCLUSIONS

ATM (Ataxia telengiectasia mutated), H2AX (histone 2AX), CDKN1A (Cyclin-dependent kinase inhibitor 1A), and TP53 (tumor protein 53) are top candidate radiation protein biomarkers. Furthermore, we recommend a panel of protein biomarkers, each with different dose and time optima, to improve individual radiation biodosimetry for discriminating between low-, moderate-, and high-dose exposures. Our findings have applications for early triage and follow-up medical assessments.

Decreased c‐Myc expression and its involvement in X‐ray‐induced apoptotic cell death of human T‐cell leukaemia cell line MOLT‐4

PURPOSE

To investigate the possible involvement of c-Myc and ceramide-c-Jun N-terminal kinase (JNK) pathway in X-ray-induced apoptotic cell death of MOLT-4 cells.

MATERIALS AND METHODS

The expressions of c-Myc protein and c-myc mRNA after X-irradiation were analysed by Western blotting and RT-PCR between radiosensitive MOLT-4 and radioresistant variant Rh-1a cells with less JNK activation than the parental cells. Apoptotic cell death was determined by a dye exclusion test, the appearance of chromatin condensation and DNA fragmentation. The effect of a JNK activator anisomycin or c-Myc inhibitor peptides (Int-H1-S6A, F8A) on the amount of c-Myc protein and on the induction of apoptosis was investigated, respectively.

RESULTS

In X-irradiated MOLT-4 cells, amounts of both c-myc mRNA and c-Myc protein rapidly decreased, which was followed by apoptotic cell death, while little change or limited reduction of c-Myc protein was observed in X-irradiated Rh-1a cells with accompanying higher cell viability. Exposure of MOLT-4 and Rh-1a cells to c-Myc inhibitor peptides similarly induced apoptotic cell death with decreases of c-Myc protein. Anisomycin rapidly induced JNK activation and a subsequent decrease of c-Myc protein, causing cell death in MOLT-4 cells. On the other hand, Rh-1a cells were more resistant to anisomycin than parental MOLT-4 cells, showing less JNK activation and a delayed decrease of c-Myc protein.

CONCLUSION

A decrease of c-Myc protein was considered important in X-ray-induced apoptotic cell death of MOLT-4 cells; activation of the JNK pathway caused reduction in the amounts of c-myc mRNA and c-Myc protein, and finally induced apoptotic cell death.

Combination chemotherapy and radiation of human squamous cell carcinoma of the head and neck augments CTL-mediated lysis

PURPOSE

The combination of systemic multiagent chemotherapy (5-fluorouracil + cisplatin) and tumor irradiation is standard of care for head and neck squamous cell carcinoma (HNSCC). Furthermore, it has been shown that sublethal doses of radiation or chemotherapeutic drugs in diverse cancer types may alter the phenotype or biology of neoplastic cells, making them more susceptible to CTL-mediated cytotoxicity. However, little is known about the potential synergistic effect of drug plus radiation on CTL killing. Here, we examined whether the combination of two chemotherapeutics and ionizing radiation enhanced CTL-mediated destruction of HNSCC more so than either modality separately, as well as the basis for the enhanced tumor cell lysis.

EXPERIMENTAL DESIGN

Several HNSCC cell lines with distinct biological features were treated with sublethal doses of cisplatin and 5-fluorouracil for 24 hours and with 10-Gy irradiation. Seventy-two hours postirradiation, tumor cells were exposed to an antigen-specific CD8+ CTL directed against carcinoembryonic antigen or MUC-1.

RESULTS

In three of three tumor cell lines tested, enhanced CTL activity was observed when the two modalities (chemotherapy and radiation) were combined as compared with target cells exposed to either modality separately. CTL-mediated lysis was MHC restricted and antigen specific and occurred almost entirely via the perforin pathway. Moreover, the combination treatment regimen led to a 50% reduction in Bcl-2 expression whereas single modality treatment had little bearing on the expression of this antiapoptotic gene.

CONCLUSIONS

Overall, these results reveal that (a) CTL killing can be enhanced by combining multiagent chemotherapy and radiation and (b) combination treatment enhanced or sensitized HNSCC to the perforin pathway, perhaps by down-regulating Bcl-2 expression. These studies thus form the rational basis for clinical trials of immunotherapy concomitant with the current standard of care of HNSCC.

Sublethal irradiation of human tumor cells modulates phenotype resulting in enhanced killing by cytotoxic T lymphocytes

Local radiation of tumor masses is an established modality for the therapy of a range of human tumors. It has recently been recognized that doses of radiation, lower than or equal to those that cause direct cytolysis, may alter the phenotype of target tissue by up-regulating gene products that may make tumor cells more susceptible to T-cell-mediated immune attack. Previously, we demonstrated that radiation increased Fas (CD95) gene expression in carcinoembryonic antigen (CEA)-expressing murine tumor cells, which consequently enhanced their susceptibility to CEA-specific CTL-mediated killing. The present study was designed to determine whether these phenomena also occur with human tumor cells. Here, 23 human carcinoma cell lines (12 colon, 7 lung, and 4 prostate) were examined for their response to nonlytic doses of radiation (10 or 20 Gy). Seventy-two hours postirradiation, changes in surface expression of Fas (CD95), as well as expression of other surface molecules involved in T-cell-mediated immune attack such as intercellular adhesion molecule 1, mucin-1, CEA, and MHC class I, were examined. Twenty-one of the 23 (91%) cell lines up-regulated one or more of these surface molecules postirradiation. Furthermore, five of five irradiated CEA(+)/A2(+) colon tumor cells lines demonstrated significantly enhanced killing by CEA-specific HLA-A2-restricted CD8(+) CTLs compared with nonirradiated counterparts. We then used microarray analysis to broaden the scope of observed changes in gene expression after radiation and found that many additional genes had been modulated. These up-regulated gene products may additionally enhance the tumor cells' susceptibility to T-cell-mediated immune attack or serve as additional targets for immunotherapy. Overall, the results of this study suggest that nonlethal doses of radiation can be used to make human tumors more amenable to immune system recognition and attack and form the rational basis for the combinatorial use of cancer vaccines and local tumor irradiation.

Short-term preoperative radiotherapy interferes with the determination of pathological parameters in rectal cancer

Short-term preoperative radiotherapy in combination with surgery has been shown to decrease the rate of local recurrence in rectal cancer patients. The effects of this type of radiotherapy on the histopathology of rectal carcinoma has been hitherto unknown. Since various histopathological factors are associated with prognosis, the study of alterations induced by irradiation is an important issue. This paper examines the histopathology of resection specimens from 1306 patients who were treated in a randomized trial that evaluated the benefits of preoperative radiotherapy. In this trial, patients were treated with short-term radiotherapy (5 x 5 Gy) and operated on within 5 days after radiation. Histopathological parameters were determined by the Pathology Review Committee of the trial and we compared tumours of patients with and without preoperative radiotherapy. Tumours of patients who were treated with preoperative radiotherapy were smaller, more often mucinous carcinomas (13% versus 7%, p < 0.001) and more often poorly differentiated (35% versus 24%, p<0.001). After radiotherapy, there was less inflammatory reaction around the tumour (extensive in 7% versus 18%, p<0.001), which was mainly caused by a decrease in T lymphocytes and neutrophil granulocytes. The fibroblastic reaction was more pronounced in the radiotherapy group (extensive in 22% versus 10%, p <0.001). Remarkable histological alterations occurred within a week after 5 days of irradiation of rectal carcinomas. The prognostic value of these factors therefore needs to be re-evaluated for irradiated patients.