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Title: SU-F-T-683: Cancer Stem Cell Hypothesis and Radiation Treatments

Abstract

Purpose: The tumor control probability in radiation therapy allows comparing different radiation treatments to each other by means of calculating the probability that a prescribed dose of radiation eradicates or controls the tumor. In the conventional approach, all cancer cells can divide unlimited number of times and the tumor control often means eradicating every malignant cell by the radiation. In recent years however, there is a mounting consensus that in a given tumor volume there is a sub-population of cells, known as cancer stem cells (CSCs) that are responsible for tumor initiation and growth. Other or progenitor cancer cells can only divide limited number of times. This entails that only cancer stem cells may nned to be eliminated in order to control the tumor. Thus one may define TCP as the probability of eliminating CSCs for the given dose of radiation. Methods: Using stochastic methods, specifically the birth-and-death Markov processes, an infinite system of equations is set for probabilities of having m cancer stem cells at time t after the start of radiation. The TCP is calculated as the probability of no cancer stem cells surviving the radiation. Two scenarios are studied. In the first situation, the TCP is calculatedmore » for a unidirectional case when CSC gives birth to another CSC or a progenitor cell. In the second scenario, a bidirectional model is studied where the progenitor cell gives rise to CSC. Results: The proposed calculations show that the calculated TCP for CSC depends on whether one adopts unidirectional or bidirectional conversion models. The bidirectional model shows significantly lower TCP values for the given dose delivered to the tumor. Conclusion: Incorporating CSC hypothesis into the TCP modeling may notably influence the dose prescription as well as the concept of the expected TCP after the radiation treatments.« less

Authors:
 [1]
  1. Pinnacle Health Cancer Center, Harrisburg, PA (United States)
Publication Date:
OSTI Identifier:
22649238
Resource Type:
Journal Article
Resource Relation:
Journal Name: Medical Physics; Journal Volume: 43; Journal Issue: 6; Other Information: (c) 2016 American Association of Physicists in Medicine; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
60 APPLIED LIFE SCIENCES; 61 RADIATION PROTECTION AND DOSIMETRY; MARKOV PROCESS; NEOPLASMS; RADIATION DOSES; RADIOTHERAPY; SIMULATION; STEM CELLS; TCP

Citation Formats

Fourkal, E. SU-F-T-683: Cancer Stem Cell Hypothesis and Radiation Treatments. United States: N. p., 2016. Web. doi:10.1118/1.4956869.
Fourkal, E. SU-F-T-683: Cancer Stem Cell Hypothesis and Radiation Treatments. United States. doi:10.1118/1.4956869.
Fourkal, E. 2016. "SU-F-T-683: Cancer Stem Cell Hypothesis and Radiation Treatments". United States. doi:10.1118/1.4956869.
@article{osti_22649238,
title = {SU-F-T-683: Cancer Stem Cell Hypothesis and Radiation Treatments},
author = {Fourkal, E},
abstractNote = {Purpose: The tumor control probability in radiation therapy allows comparing different radiation treatments to each other by means of calculating the probability that a prescribed dose of radiation eradicates or controls the tumor. In the conventional approach, all cancer cells can divide unlimited number of times and the tumor control often means eradicating every malignant cell by the radiation. In recent years however, there is a mounting consensus that in a given tumor volume there is a sub-population of cells, known as cancer stem cells (CSCs) that are responsible for tumor initiation and growth. Other or progenitor cancer cells can only divide limited number of times. This entails that only cancer stem cells may nned to be eliminated in order to control the tumor. Thus one may define TCP as the probability of eliminating CSCs for the given dose of radiation. Methods: Using stochastic methods, specifically the birth-and-death Markov processes, an infinite system of equations is set for probabilities of having m cancer stem cells at time t after the start of radiation. The TCP is calculated as the probability of no cancer stem cells surviving the radiation. Two scenarios are studied. In the first situation, the TCP is calculated for a unidirectional case when CSC gives birth to another CSC or a progenitor cell. In the second scenario, a bidirectional model is studied where the progenitor cell gives rise to CSC. Results: The proposed calculations show that the calculated TCP for CSC depends on whether one adopts unidirectional or bidirectional conversion models. The bidirectional model shows significantly lower TCP values for the given dose delivered to the tumor. Conclusion: Incorporating CSC hypothesis into the TCP modeling may notably influence the dose prescription as well as the concept of the expected TCP after the radiation treatments.},
doi = {10.1118/1.4956869},
journal = {Medical Physics},
number = 6,
volume = 43,
place = {United States},
year = 2016,
month = 6
}
  • Purpose: To investigate the significance of CD44 protein expression on the treatment outcomes of radiation therapy in patients with oropharyngeal squamous cell carcinoma (OPSCC) with or without p16 protein expression in the tumor tissue. Methods and Materials: We reviewed the medical records of 58 OPSCC patients who had undergone radiation therapy and examined the tumor tissue expressions of CD44 and p16 protein by immunohistochemical staining. The correlations between the expressions of these proteins and the patients' treatment outcomes were analyzed. Results: The data of 58 consecutive OPSCC patients who had undergone definitive intensity modulated radiation therapy were analyzed. The male/femalemore » ratio was 55:3, and the median age was 64 years. The clinical stage of the disease was stage II in 7 patients, stage III in 5 patients, stage IVA in 35 patients, and stage IVB in 11 patients. Of the patients, 79% received additional induction and/or concurrent chemotherapy. The median follow-up duration was 34 months. The 3-year overall survival, progression-free survival (PFS) and locoregional control (LRC) rates of all the patients, regardless of the results of immunohistochemistry, were 73%, 64% and 76%, respectively. The PFS and LRC rates in the CD44{sup −} patients (86% and 93%, respectively) were significantly higher than those in the CD44{sup +} patients (57% and 70%, respectively). The PFS and LRC rates in the p16{sup +} patients (83% and 90%, respectively) were significantly higher than those in the p16{sup −} patients (45% and 61%, respectively). Patients who were CD44{sup −}/p16{sup +} showed the best LRC rates, and those who were CD44{sup +}/p16{sup −} showed the worst PFS and LRC rates among all the groups. Conclusions: Profiling of CD44 and p16 protein expressions by immunohistochemical staining is useful for predicting the treatment outcomes in patients with OPSCC undergoing definitive intensity modulated radiation therapy.« less
  • Purposes: The presence of cancer stem cells (CSCs) in a solid tumor could result in poor tumor control probability. The purposes are to study CSC radiosensitivity parameters α and β and their correlation to CSC levels to understand the underlying radioresistance mechanisms and enable individualized treatment design. Methods: Four established breast cancer cell lines (MCF-7, T47D, MDA-MB-231, and SUM159PT) were irradiated in vitro using single radiation doses of 0, 2, 4, 6, 8 or 10 Gy. The fractions of CSCs in each cell lines were determined using cancer stem cell markers. Mammosphere assays were also performed to better estimate themore » number of CSCs and represent the CSC repopulation in a human solid tumor. The measured cell surviving fractions were fitted using the Linear-quadratic (LQ) model with independent fitting parameters: α-TC, β-TC (TCs), α-CSC, β-CSC (CSCs), and fs (the percentage of CSCs in each sample). Results: The measured fs increased following the irradiation by MCF-7 (0.1%), T47D (0.9%), MDA-MB-231 (1.18%) and SUM159T (2.46%), while decreasing surviving curve slopes were observed, indicating greater radioresistance, in the opposite order. The fitting yielded the radiosensitive parameters for the MCF-7: α-TC=0.1±0.2Gy{sup −1}, β-TC= 0.08 ±0.14Gy{sup −2}, α-CSC=0.04±0.07Gy{sup −1}, β-CSC =0.02±0.3Gy{sup −2}; for the SUM159PT, α-TC=0.08±0.25 Gy{sup −1}, β-TC=0.02±0.02Gy{sup −2}, α-CSC=0.04±0.18Gy{sup −1}, β-CSC =0.004±0.24Gy{sup −2}. In the mammosphere assay, where fs were higher than the corresponding cell line assays, there was almost no shoulder found in the surviving curves (more radioresistant in mammosphere assays) yielding β-CSC of approximately 0. Conclusion: Breast cancer stem cells were more radioresistant characterized by smaller α and β values compared to differentiated breast cancer cells. Percentage of breast cancer stem cells strongly correlated to overall tumor radioresistance. This observation suggested the feasibility of individualized radiotherapy prescription based on the fractions of cancer stem cells found in biopsy.« less
  • Purpose: A subpopulation of cancer stem-like cells (CSLC) is hypothesized to exist in different cancer cell lines and to mediate radioresistance in solid tumors. Methods and Materials: Cells were stained for CSLC markers and sorted (fluorescence-activated cell sorter/magnetic beads) to compare foci and radiosensitivity of phosphorylated histone H2AX at Ser 139 (gamma-H2AX) in sorted vs. unsorted populations in eight cell lines from different organs. CSLC properties were examined using anchorage-independent growth and levels of activated Notch1. Validation consisted of testing tumorigenicity and postirradiation enrichment of CSLC in xenograft tumors. Results: The quantity of CSLC was generally in good agreement withmore » primary tumors. CSLC from MDA-MB-231 (breast) and Panc-1 and PSN-1 (both pancreatic) cells had fewer residual gamma-H2AX foci than unsorted cells, pointing to radioresistance of CSLC. However, only MDA-MB-231 CSLC were more radioresistant than unsorted cells. Furthermore, MDA-MB-231 CSLC showed enhanced anchorage-independent growth and overexpression of activated Notch1 protein. The expression of cancer stem cell surface markers in the MDA-MB-231 xenograft model was increased after exposure to fractionated radiation. In contrast to PSN-1 cells, a growth advantage for MDA-MB-231 CSLC xenograft tumors was found compared to tumors arising from unsorted cells. Conclusions: CSLC subpopulations showed no general radioresistant phenotype, despite the quantities of CSLC subpopulations shown to correspond relatively well in other reports. Likewise, CSLC characteristics were found in some but not all of the tested cell lines. The reported problems in testing for CSLC in cell lines may be overcome by additional techniques, beyond sorting for markers.« less
  • The echinoderm microtubule-associated protein-like 4(EML4) – anaplastic lymphoma kinase (ALK) fusion gene has been identified as a driver mutation in non-small-cell lung cancer (NSCLC). However, the role of EML4-ALK in malignant transformation is not entirely clear. Here, for the first time, we showed that H1299 NSCLC cells stably expressing EML4-ALK acquire EMT phenotype, associated with enhanced invasive migration and increased expression of EMT-inducing transcription factors. H1299-EML4-ALK cells also displayed cancer stem cell-like properties with a concomitant up-regulation of CD133 and enhanced ability of mammospheres formation. Moreover, we found that inhibition of ERK1/2 reversed EMT induced by EML4-ALK in H1299 cells.more » Taken together, these results suggested that EML4-ALK induced ERK activation is mechanistically associated with EMT phenotype. Thus, inhibition of ERK signaling pathway could be a potential strategy in treatment of NSCLC patients with EML4-ALK translocation. - Highlights: • EML4-ALK induced epithelial–mesenchymal transition in H1299 cells. • Expression of EML4-ALK promotes invasion and migration in vitro. • EML4-ALK enhanced sphere formation and stem cell-like properties in H1299 cells. • Blockage of ERK1/2 reverse Epithelial–Mesenchymal transition induced by EML4-ALK.« less
  • Research highlights: {yields} Four oral squamous cancer cell lines (OSCCL) were analyzed for cancer stem cells (CSCs). {yields} Single cell derived colonies of OSCCL express CSC-marker CD133 differentially. {yields} Monoclonal cell lines showed reduced sensitivity for Paclitaxel. {yields} In situ CD133{sup +} cells are slow cycling (Ki67-) indicating a reduced drug sensitivity. {yields} CD133{sup +} and CSC-like cells can be obtained from single colony forming cells of OSCCL. -- Abstract: Resistance of oral squamous cell carcinomas (OSCC) to conventional chemotherapy or radiation therapy might be due to cancer stem cells (CSCs). The development of novel anticancer drugs requires a simplemore » method for the enrichment of CSCs. CSCs can be enriched from OSCC cell lines, for example, after cultivation in serum-free cell culture medium (SFM). In our study, we analyzed four OSCC cell lines for the presence of CSCs. CSC-like cells could not be enriched with SFM. However, cell lines obtained from holoclone colonies showed CSC-like properties such as a reduced rate of cell proliferation and a reduced sensitivity to Paclitaxel in comparison to cells from the parental lineage. Moreover, these cell lines differentially expressed the CSC-marker CD133, which is also upregulated in OSCC tissues. Interestingly, CD133{sup +} cells in OSCC tissues expressed little to no Ki67, the cell proliferation marker that also indicates reduced drug sensitivity. Our study shows a method for the isolation of CSC-like cell lines from OSCC cell lines. These CSC-like cell lines could be new targets for the development of anticancer drugs under in vitro conditions.« less