IADR Abstract Archives
Combination of chemo-immunotherapy eliminates oral cancer stem cells
Objectives: To demonstrate the stage of differentiation dependent susceptibility of oral cancer cells to NK cell mediated cytotoxicity. To show the mechanisms by which regulatory Natural Killer cells (NK cells) differentiate cancer stem cells and to provide evidence that combination of chemotherapy and immunotherapy eliminate oral cancer stem cells.
Methods: Oral squamous cell carcinomas (OSCCs) and oral squamous carcinoma stem cells (OSCSCs) were used. Function of NK cells was assessed using chromium 51 release assay, ELISA, flow cytometry to analyze the surface expression of MHC-class I, B7H1, CD44 and CD54 and time lapse microscopy. Supernatant and fixed NK anergized NK cells were used to induce differentiation of cancer stem cells. Antibodies to IFN-gamma and TNF-alpha, and Cisplatin and Paclitaxel were used as chemotherapeutic agents.
Results: NK cells lysed stem-like tumors significantly more than the well-differentiated tumors. After lysis of a proportion of cancer stem cells, NK cells lost their cytotoxic function and were conditioned to release cytokines to differentiate the remaining of stem cells through the synergistic actions of IFN-gamma and TNF-alpha. CD16 receptors were responsible for conditioning of NK cells to support differentiation. Differentiated cancer stem cells did not metastasize, grew slower and were highly susceptible to chemotherapy whereas cancer stem cells grew faster, metastasized and were resistant to chemotherapy.
Conclusions: CD16+CD56dimCD69neg NK cells are important for the selection of stem cells whereas the regulatory CD16negCD56brightCD69+NK cells mediate differentiation. Based on our data, we propose combinatorial chemotherapy and immunotherapy with NK cells for the treatment of oral cancers since both stem cells and differentiated tumors are eliminated by such strategy. The concept of split anergy in NK cell, generation of regulatory NK and its contribution to tumor differentiation, tissue repair and regeneration, resolution of inflammation and tumor resistance will be discussed.
Methods: Oral squamous cell carcinomas (OSCCs) and oral squamous carcinoma stem cells (OSCSCs) were used. Function of NK cells was assessed using chromium 51 release assay, ELISA, flow cytometry to analyze the surface expression of MHC-class I, B7H1, CD44 and CD54 and time lapse microscopy. Supernatant and fixed NK anergized NK cells were used to induce differentiation of cancer stem cells. Antibodies to IFN-gamma and TNF-alpha, and Cisplatin and Paclitaxel were used as chemotherapeutic agents.
Results: NK cells lysed stem-like tumors significantly more than the well-differentiated tumors. After lysis of a proportion of cancer stem cells, NK cells lost their cytotoxic function and were conditioned to release cytokines to differentiate the remaining of stem cells through the synergistic actions of IFN-gamma and TNF-alpha. CD16 receptors were responsible for conditioning of NK cells to support differentiation. Differentiated cancer stem cells did not metastasize, grew slower and were highly susceptible to chemotherapy whereas cancer stem cells grew faster, metastasized and were resistant to chemotherapy.
Conclusions: CD16+CD56dimCD69neg NK cells are important for the selection of stem cells whereas the regulatory CD16negCD56brightCD69+NK cells mediate differentiation. Based on our data, we propose combinatorial chemotherapy and immunotherapy with NK cells for the treatment of oral cancers since both stem cells and differentiated tumors are eliminated by such strategy. The concept of split anergy in NK cell, generation of regulatory NK and its contribution to tumor differentiation, tissue repair and regeneration, resolution of inflammation and tumor resistance will be discussed.