1. Electrotransfer of plasmid DNA radiosensitizes B16F10 tumors through activation of immune responseMonika Savarin, Urška Kamenšek, Maja Čemažar, Richard Heller, Gregor Serša, 2017, original scientific article Abstract: Tumor irradiation combined with adjuvant treatments, either vascular targeted or immunomodulatory, is under intense investigation. Gene electrotransfer of therapeutic genes is one of these approaches. The aim of this study was to determine, whether gene electrotransfer of plasmid encoding shRNA for silencing endoglin, with vascular targeted effectiveness, can radiosensitize melanoma B16F10 tumors. Materials and methods. The murine melanoma B16F10 tumors, growing on the back of C57Bl/6 mice, were treated by triple gene electrotransfer and irradiation. The antitumor effect was evaluated by determination of tumor growth delay and proportion of tumor free mice. Furthermore, histological analysis of tumors (necrosis, apoptosis, proliferation, vascularization, presence of hypoxia and infiltration of immune cells,) was used to evaluate the therapeutic mechanisms. Results. Gene electrotransfer of plasmid silencing endoglin predominantly indicated vascular targeted effects of the therapy, since significant tumor growth delay and 44% of tumor free mice were obtained. In addition, irradiation had minor effects on radioresistant melanoma, with 11% of mice tumor free. The combined treatment resulted in excellent effectiveness with 88% of mice tumor free, with more than half resistant to secondary tumor challenge, which was observed also with the plasmid devoid of the therapeutic gene. Histological analysis of tumors in the combined treatment group, demonstrated similar mode of action of the gene electrotransfer of plasmid encoding shRNA for silencing endoglin and devoid of it, both through the induction of an immune response. Conclusions. The results of this study indicate that irradiation can in radioresistant melanoma tumors, by release of tumor associated antigens, serve as activator of the immune response, besides directly affecting tumor cells and vasculature. The primed antitumor immune response can be further boosted by gene electrotransfer of plasmid, regardless of presence of the therapeutic gene, which was confirmed by the high radiosensitization, resulting in prolonged tumor growth delay and 89% of tumor free mice that were up to 63% resistant to secondary challenge of tumor. In addition, gene electrotransfer of therapeutic plasmid for silencing endoglin has also a direct effect on tumor vasculature and tumors cells; however in combination with radiotherapy this effect was masked by pronounced immune response.
Keywords: gene therapy, electrotransfer, plasmid, irradiation, immune response, melanoma
Published in DiRROS: 24.05.2024; Views: 79; Downloads: 31
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2. Adjuvant TNF-a therapy to electrochemotherapy with intravenous cisplatin in murine sarcoma exerts synergistic antitumor effectivenessMaja Čemažar, Vesna Todorović, Janez Ščančar, Urša Lampreht Tratar, Monika Savarin, Urška Kamenšek, Simona Kranjc Brezar, Andrej Cör, Gregor Serša, 2015, original scientific article Abstract: Background. Electrochemotherapy is a tumour ablation modality, based on electroporation of the cell membrane, allowing non-permeant anticancer drugs to enter the cell, thus augmenting their cytotoxicity by orders of magnitude. In preclinical studies, bleomycin and cisplatin proved to be the most suitable for clinical use. Intravenous administration of cisplatin for electrochemotherapy is still not widely accepted in the clinics, presumably due to its lower antitumor effectiveness, but adjuvant therapy by immunomodulatory or vascular-targeting agents could provide a way for its potentiation. Hence, the aim of the present study was to explore the possibility of adjuvant tumour necrosis factor % (TNF-%) therapy to potentiate antitumor effectiveness of electrochemotherapy with intravenous cisplatin administration in murine sarcoma. Materials and methods. In vivo study was designed to evaluate the effect of TNF-% applied before or after the electrochemotherapy and to evaluate the effect of adjuvant TNF-% on electrochemotherapy with different cisplatin doses. Results. A synergistic interaction between TNF-% and electrochemotherapy was observed. Administration of TNF-% before the electrochemotherapy resulted in longer tumour growth delay and increased tumour curability, and was significantly more effective than TNF-% administration after the electrochemotherapy. Tumour analysis revealed increased platinum content in tumours, TNF-% induced blood vessel damage and increased tumour necrosis after combination of TNF-% and electrochemotherapy, indicating an anti-vascular action of TNF-%. In addition, immunomodulatory effect might have contributed to curability rate of the tumours. Conclusion. Adjuvant intratumoural TNF-% therapy synergistically contributes to electrochemotherapy with intravenous cisplatin administration. Due to its potentiation at all doses of cisplatin, the combined treatment is predicted to be effective also in tumours, where the drug concentration is suboptimal or in bigger tumours, where electrochemotherapy with intravenous cisplatin is not expected to be sufficiently effective.
Keywords: electrochemotherapy, TNF, adjuvant immunotherapy, cisplatin
Published in DiRROS: 17.04.2024; Views: 160; Downloads: 30
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3. Gene immunotherapy of colon carcinoma with IL-2 and IL-12 using gene electrotransferTilen Komel, Maša Omerzel, Urška Kamenšek, Katarina Žnidar, Urša Lampreht Tratar, Simona Kranjc Brezar, Klemen Dolinar, Sergej Pirkmajer, Gregor Serša, Maja Čemažar, 2023, original scientific article Abstract: Gene immunotherapy has become an important approach in the treatment of cancer. One example is the introduction of genes encoding immunostimulatory cytokines, such as interleukin 2 and interleukin 12, which stimulate immune cells in tumours. The aim of our study was to determine the effects of gene electrotransfer of plasmids encoding interleukin 2 and interleukin 12 individually and in combination in the CT26 murine colon carcinoma cell line in mice. In the in vitro experiment, the pulse protocol that resulted in the highest expression of IL-2 and IL-12 mRNA and proteins was used for the in vivo part. In vivo, tumour growth delay and also complete response were observed in the group treated with the plasmid combination. Compared to the control group, the highest levels of various immunostimulatory cytokines and increased immune infiltration were observed in the combination group. Long-term anti-tumour immunity was observed in the combination group after tumour re-challenge. In conclusion, our combination therapy efficiently eradicated CT26 colon carcinoma in mice and also generated strong anti-tumour immune memory.
Keywords: colon carcinoma, gene electrotransfer, gene immunotherapy
Published in DiRROS: 21.03.2024; Views: 174; Downloads: 77
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4. Evaluation of shRNA-mediated gene silencing by electroporation in LPB fibrosarcoma cellsSuzana Vidic, Urška Kamenšek, Maja Čemažar, 2008, original scientific article Abstract: Background. Silencing oncogenes or other genes that contribute to tumor malignancy and progression offers a promising approach to treating cancer. Specific and efficient silencing of gene expression can be achieved by RNA interference (RNAi) technology using small interfering RNA (siRNA) or short hairpin RNA (shRNA). However, a major challenge in RNAi technology is effective delivery of interfering molecules into target cells. The aim of our study was to evaluate electroporation as a perspective method for efficient invitro transfection of LPB fibrosarcoma cells with plasmid DNA expressing shRNA. Methods. Induction of shRNA-mediated gene silencing by electroporation was determined by fluorescence microscopy, flow cytometry and western blot analysis. The effect of electroporation conditions on cell survival and proliferation was determined by clonogenic assay. Results and conclusions. Ourresults demonstrated that electroporation is a feasible and effective method for delivery of plasmid DNA expressing shRNA into cancer cells in vitro. Electrotransfection of murine LPB fibrosarcoma cells, continuously expressing green fluorescence protein - GFP (LPBGFP), with plasmid DNA encoding shRNA-GFP, reduced GFP expression, which was determined on the protein level, as well as by measurement of GFP fluorescence intensity. A pronounced reduction in GFP expression level was detected from the second to the fifth day after treatment. Moreover, the method is easy to perform and showed low cell damaging effects, which are the most important and preferential factors for further in vivo studies.
Published in DiRROS: 08.03.2024; Views: 148; Downloads: 38
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5. Targeted gene therapy in radiotherapyUrška Kamenšek, Gregor Serša, 2008, review article Abstract: The dramatic pace in development of gene therapy over the past decades has made it a realistic alternative for the treatment of cancer. Radiotherapy, on the other hand, is one of the most commonly used and well established cancer treatment modalities. The latest improvements in the physical targeting ability of radiotherapy and understanding of the molecular mechanism involved in the cellular response to ionizing radiation have presented an opportunity to combine radiotherapy with gene therapy. This review article will focus on gene therapy strategies that can be used to enhance the effectiveness of radiotherapy, with an emphasis on transcriptional targeting approaches.
Published in DiRROS: 07.03.2024; Views: 167; Downloads: 41
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6. Radiosenzibilizacija tumorjev z elektroprenosom plazmida za dve antiangiogeni tarčiMonika Savarin, Katarina Žnidar, Gregor Serša, Tilen Komel, Maja Čemažar, Urška Kamenšek, 2023, published scientific conference contribution abstract Keywords: miši, elektroprenos genov, gensko zdravljenje
Published in DiRROS: 19.06.2023; Views: 383; Downloads: 146
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7. Maintenance and gene electrotransfer efficiency of antibiotic resistance gene-free plasmids encoding mouse, canine and human interleukin-12 orthologuesUrška Kamenšek, Andrej Renčelj, Tanja Jesenko, Tinkara Remic, Gregor Serša, Maja Čemažar, 2022, original scientific article Abstract: Interleukin 12 (IL-12) is a cytokine used as a therapeutic molecule in cancer immunotherapy. Gene electrotransfer mediated delivery of IL-12 gene has reached clinical evaluation in the USA using a plasmid that in addition to IL- 12 gene also carry an antibiotic resistance gene needed for its production in bacteria. In Europe however, Eu- ropean Medicines Agency recommends against the use of antibiotics during the production of clinical grade plasmids. We have prepared several antibiotic resistance gene-free plasmids using an antibiotic-free selection strategy called operator-repressor titration, including plasmids encoding mouse, canine and human IL-12 orthologues. The aim of this study was to evaluate the maintenance of these plasmids in bacterial culture and test their transfection efficiency using gene electrotransfer. Plasmid maintenance was evaluated by determining plasmid yields and topologies after subculturing transformed bacteria. Transfection efficiency was evaluated by determining the plasmid copy number, expression and cytotoxicity after gene electrotransfer to mouse, canine and human melanoma cells. The results demonstrated that our IL-12 plasmids without an antibiotic resistance gene are stably maintained in bacteria and provide sufficient IL-12 expression after in vitro gene electrotransfer; therefore, they have the potential to proceed to further in vivo evaluation studies.
Keywords: electrotransfer, interleukin-12, immunotherapy, mammals
Published in DiRROS: 23.09.2022; Views: 620; Downloads: 279
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8. Potentiation of electrochemotherapy effectiveness by immunostimulation with IL-12 gene electrotransfer in mice is dependent on tumor immune statusKatja Uršič Valentinuzzi, Špela Kos, Urška Kamenšek, Maja Čemažar, Simona Miceska, Boštjan Markelc, Simon Buček, Barbara Starešinič, Veronika Kloboves-Prevodnik, Richard Heller, Gregor Serša, 2021, original scientific article Abstract: Electrochemotherapy (ECT) exhibits high therapeutic effectiveness in the clinic, achieving up to 80% local tumor control but without a systemic (abscopal) effect. Therefore, we designed a combination therapy consisting of ECT via intratumoral application of bleomycin, oxaliplatin or cisplatin with peritumoral gene electrotransfer of a plasmid encoding interleukin-12 (p. t. IL-12 GET). Our hypothesis was that p. t. IL-12 GET potentiates the effect of ECT on local and systemic levels and that the potentiation varies depending on tumor immune status. Therefore, the combination therapy was tested in three immunologically different murine tumor models. In poorly immunogenic B16F10 melanoma, IL-12 potentiated the antitumor effect of ECT with biologically equivalent low doses of cisplatin, oxaliplatin or bleomycin. The most pronounced potentiation was observed after ECT using cisplatin, resulting in a complete response rate of 38% and an abscopal effect. Compared to B16F10 melanoma, better responsiveness to ECT was observed in more immunogenic 4%T1 mammary carcinoma and CT26 colorectal carcinoma. In both models, p. t. IL-12 GET did not significantly improve the therapeutic outcome of ECT using any of the chemotherapeutic drugs. Collectively, the effectiveness of the combination therapy depends on tumor immune status. ECT was more effective in more immunogenic tumors, but GET exhibited greater contribution in less immunogenic tumors. Thus, the selection of the therapy, namely, either ECT alone or combination therapy with p. t. IL-12, should be predominantly based on tumor immune status.
Keywords: electrochemotherapy, gene electrotransfer, interleukin-12
Published in DiRROS: 21.09.2022; Views: 617; Downloads: 212
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9. Evaluation of a novel plasmid for simultaneous gene electrotransfer-mediated silencing of CD105 and CD146 in combination with irradiationMonika Savarin, Urška Kamenšek, Katarina Žnidar, Vesna Todorović, Gregor Serša, Maja Čemažar, 2021, original scientific article Abstract: Targeting tumor vasculature through specific endothelial cell markers represents a promising approach for cancer treatment. Here our aim was to construct an antibiotic resistance gene-free plasmid encoding shRNAs to simultaneously target two endothelial cell markers, CD105 and CD146, and to test its functionality and therapeutic potential in vitro when delivered by gene electrotransfer (GET) and combined with irradiation (IR). Functionality of the plasmid was evaluated by determining the silencing of the targeted genes using qRT-PCR. Antiproliferative and antiangiogenic effects were determined by the cytotoxicity assay tube formation assay and wound healing assay in murine endothelial cells 2H-11. The functionality of the plasmid construct was also evaluated in malignant melanoma tumor cell line B16F10. Additionally, potential activation of immune response was measured by induction of DNA sensor STING and proinflammatory cytokines by qRT-PCR in endothelial cells 2H-11. We demonstrated that the plasmid construction was successful and can efficiently silence the expression of the two targeted genes. As a consequence of silencing, reduced migration rate and angiogenic potential was confirmed in 2H-11 endothelial cells. Furthermore, induction of DNA sensor STING and proinflammatory cytokines were determined, which could add to the therapeutic effectiveness when used in vivo. To conclude, we successfully constructed a novel plasmid DNA with two shRNAs, which holds a great promise for further in vivo testing.
Keywords: CD105, CD146, plasmid, gene electrotransfer
Published in DiRROS: 21.09.2022; Views: 575; Downloads: 327
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10. Mutational burden, MHC-I expression and immune infiltration as limiting factors for in situ vaccination by TNF[alfa] and IL-12 gene electrotransferUrška Kamenšek, Katja Uršič Valentinuzzi, Boštjan Markelc, Maja Čemažar, Vita Šetrajčič Dragoš, Gregor Serša, 2021, original scientific article Abstract: In situ vaccination is a promising immunotherapeutic approach, where various local ablative therapies are used to induce an immune response against tumor antigens that are released from the therapy-killed tumor cells. We recently proposed using intratumoral gene electrotransfer for concomitant transfection of a cytotoxic cytokine tumor necrosis factor-% (TNF%) to induce in situ vaccination, and an immunostimulatory cytokine interleukin 12 (IL-12) to boost the primed immune response. Here, our aim was to test the local and systemic effectiveness of the approach in tree syngeneic mouse tumor models and associate it with tumor immune profiles, characterized by tumor mutational burden, immune infiltration and expression of PD-L1 and MHC-I on tumor cells. While none of the tested characteristic proved predictive for local effectiveness, high tumor mutational burden, immune infiltration and MHC-I expression were associated with higher abscopal effectiveness. Hence, we have confirmed that both the abundance and presentation of tumor antigens as well as the absence of immunosuppressive mechanisms are important for effective in situ vaccination. These findings provide important indications for future development of in situ vaccination based treatments, and for the selection of tumor types that will most likely benefit from it.
Keywords: in situ vaccination, gene electrotransfer, interleukin 12, tumor necrosis factor [alfa]
Published in DiRROS: 19.09.2022; Views: 587; Downloads: 190
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