Project description:Rectal cancer is most frequently diagnosed at a locally advanced stage and treated by neoadjuvant chemoradiation. Current efforts to improve treatment outcome are focused on intensifying neoadjuvant chemotherapy, which is however associated with higher levels of toxicity. To discover alternative strategies, we established patient-derived rectal cancer organoids (PDOs) that reflect clinical radiosensitivity and used these organoids to screen 1596 drug-radiation combinations. We found that inhibitors of RAS-MAPK signaling, especially MEK inhibitors, strongly enhance radiation response. Mechanistically, MEK inhibitors suppressed radiation-induced activation of RAS-MAPK signaling, and selectively downregulated RAD51, a key component of the homologous recombination DNA repair pathway. Through testing drug-drug-radiation combinations in organoids and cell lines, we identified that a combined PARP and MEK inhibition can further enhance radiosensitivity of colorectal cancers, which was confirmed in mouse xenograft models. Our data support clinical testing of MEK and PARP combination therapy with radiation in locally advanced rectal cancers as an alternative to chemoradiation Microarrays were used to investigate the effect of radiation treatment on gene expression in three patient-derived colorectal cancer organoid lines.
Project description:Locally advanced rectal cancer is usually treated by neoadjuvant chemoradiotherapy. However, tumor response rates to this treatment vary greatly. Thus, most patients do not reach a complete remission and have to undergo tumor resection. In the present study, we introduce a patient-derived rectal cancer organoid platform that reflects clinical radiosensitivity and use this to screen 1596 drug-radiation combinations. We identify inhibitors of RAS-MAPK signaling, especially MEK inhibitors, strongly synergizing with radiation response. Mechanistically, MEK inhibitors suppressed radiation-induced activation of RAS-MAPK signaling, and selectively downregulated the homologous recombination DNA repair pathway component RAD51, thereby achieving radio-enhancement. Through testing drug-drug-radiation combinations in organoids and cell lines, we identified synergism between PARP and MEK inhibitors to further enhance the effect of radiation. Our data support clinical testing of combined MEK and PARP inhibition with radiotherapy in locally advanced rectal cancers.
Project description:KRAS mutation is a common driver in solid tumors, and KRAS-mutated tumors are relatively resistant to radiotherapy. Therefore, we investigated the combined effect of radiation and KRAS-MEK inhibitors (AMG510 and trametinib) in KRAS-mutated tumors.
Project description:KRAS mutation is a common driver in solid tumors, and KRAS-mutated tumors are relatively resistant to radiotherapy. Therefore, we investigated the combined effect of radiation and KRAS-MEK inhibitors (AMG510 and trametinib) in KRAS-mutated tumors.
Project description:Patients with BRAF-mutated colorectal cancer (BRAFV600E CRC) are currently treated by a combination of BRAF inhibitor and anti-EGFR antibody with or without MEK inhibitor. A fundamental problem in treating patients with BRAFV600E CRC is intrinsic and/or acquired resistance to this combination therapy. By screening 78 compounds, we identified tretinoin, a retinoid, as a compound that synergistically enhances the antiproliferative effect of a combination of BRAF inhibition and MEK inhibition with or without EGFR inhibition on BRAFV600E CRC cells. This synergistic effect was also exerted by other retinoids. Tretinoin, added to BRAF inhibitor and MEK inhibitor, upregulated PARP, BAK, and p-H2AX. When either RARα or RXRα was silenced, the increase in cleaved PARP expression by the addition of TRE to ENC/BIN or ENC/BIN/CET was canceled. Our results suggest that the mechanism of the synergistic antiproliferative effect involves modulation of the Bcl-2 family and the DNA damage response that affects apoptotic pathways, and this synergistic effect is induced by RARα- or RXRα-mediated apoptosis. Tretinoin also enhanced the antitumor effect of a combination of BRAF inhibitor and anti-EGFR antibody with or without MEK inhibitor in a BRAFV600E CRC xenograft mouse model. Our data provide a rationale for developing retinoids as a new combination agent to overcome resistance to the combination therapy for patients with BRAFV600E CRC.
Project description:Patients with BRAF-mutated colorectal cancer (BRAFV600E CRC) are currently treated by a combination of BRAF inhibitor and anti-EGFR antibody with or without MEK inhibitor. A fundamental problem in treating patients with BRAFV600E CRC is intrinsic and/or acquired resistance to this combination therapy. By screening 78 compounds, we identified tretinoin, a retinoid, as a compound that synergistically enhances the antiproliferative effect of a combination of BRAF inhibition and MEK inhibition with or without EGFR inhibition on BRAFV600E CRC cells. This synergistic effect was also exerted by other retinoids. Tretinoin, added to BRAF inhibitor and MEK inhibitor, upregulated PARP, BAK, and p-H2AX. When either RARα or RXRα was silenced, the increase in cleaved PARP expression by the addition of TRE to ENC/BIN or ENC/BIN/CET was canceled. Our results suggest that the mechanism of the synergistic antiproliferative effect involves modulation of the Bcl-2 family and the DNA damage response that affects apoptotic pathways, and this synergistic effect is induced by RARα- or RXRα-mediated apoptosis. Tretinoin also enhanced the antitumor effect of a combination of BRAF inhibitor and anti-EGFR antibody with or without MEK inhibitor in a BRAFV600E CRC xenograft mouse model. Our data provide a rationale for developing retinoids as a new combination agent to overcome resistance to the combination therapy for patients with BRAFV600E CRC.
Project description:Radiotherapy constitutes a pivotal approach in the management of pelvic malignant tumors. Despite notable strides in radiation technology, the incidence of collateral damage to neighboring normal tissues remains a prominent concern. Radiation-induced rectal injury (RRI) significantly impacts the postoperative quality of life of patients undergoing pelvic radiotherapy. We gathered RRI tissues alongside non-irradiated rectal tissues for a quantitative proteomic examination employing data-independent acquisition proteomics. Our analysis unveiled differentially expressed proteins (DEPs). Gene Ontology and Kyoto Encyclopedia of Genes and Genome enrichment analyses of DEPs uncovered conventional pathway modifications such as cytokine activation and extracellular matrix alterations, alongside emerging potential biological mechanisms implicated in RRI, including neutrophil extracellular traps, macrophage-to-myofibroblast transition, and metabolic reprogramming.
Project description:Biopsy specimens were collected from rectal cancer before starting preoperative radiotherapy.The expression profiles were determined using Affymetrix Human Genome U95 version 2 arrays.Comparison between the sample groups allow to identify a set of discriminating genes that can be used for characterization of responders and nonresponders to preoperative radiotherapy in rectal cancer. Keywords: repeat