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Updated: Jun 27, 2026
Development and Maintenance of a Preclinical Patient Derived Tumor Xenograft Model for the Investigation of Novel Anti-Cancer Therapies
Published on: September 30, 2016
Synergistic Inhibition of Colorectal Cancer Growth by Combined PI3K and COX-2 Blockade in Cell Lines and
Emily Nghiem1,2, Ariel Tzamarot2,3,4, Terence Li2,3
1Department of Surgery, Albert Einstein College of Medicine, and Montefiore Medical Center, Bronx, NY 10467, USA.
Abstract:
Background/Objectives: PI3K/AKT/mTOR is a key pathway in cell proliferation, metabolism, and survival. Activating PIK3CA mutations are seen in up to 20% of colorectal cancers and are associated with increased cyclo-oxygenase-2 (COX-2) expression. Recent studies demonstrated a significant survival benefit from taking low-dose aspirin, a nonselective COX inhibitor, supporting further exploration of the synergistic effects of combined PI3Kα inhibitor (inavolisib) and COX-2 inhibitor (celecoxib) therapy. Methods: The effects of celecoxib-inavolisib combination treatment were tested on human colorectal cancer cell lines and patient-derived organoid models. Experiments included cell viability and colony formation assays, immunoblotting, and immunofluorescence. Results: We found that celecoxib and inavolisib demonstrated synergy in suppressing the growth of colorectal cancer cell lines, grown in both 2D and 3D cell culture, regardless of PIK3CA mutation status. In patient-derived organoid models, while synergy was seen in both organoids, growth of the PIK3CA mutated organoid was more potently suppressed. Immunoblotting of cells after combination treatment showed decreased expression of mitogenic signaling marker p-AKT across all 2D cell lines and in both cell lines grown as 3D spheroids, as well as increased expression of apoptotic marker cPARP in four out of five 2D cell lines and in both cell lines grown as 3D spheroids. Immunofluorescence staining of organoids after combination treatment, however, showed no significant increase in expression of apoptotic marker Cas-3 nor in mitogenic marker Ki-67 in either organoid. Furthermore, an apoptosis assay performed on two cell lines showed no significant increase in Annexin V or phosphatidylserine staining. Conclusions: Celecoxib and inavolisib demonstrated synergy in suppressing the growth of both colorectal cancer cell lines and patient-derived organoids, though PIK3CA mutation status did not appear to affect drug efficacy in cell lines as it did in patient-derived organoids. Potential compensatory or resistance mechanisms might include oncogene drivers in the MAPK/ERK pathway. When compared to monotherapy, combination therapy was the only drug condition to significantly increase the percentage of apoptotic cells based on Annexin V and phosphatidylserine staining, and this effect was only seen in the PIK3CA mutated cell line. Ultimately, our findings provide preliminary support for celecoxib-inavolisib combination treatment as a rational therapeutic avenue warranting further preclinical investigation.
Insights
Combining PI3Kα inhibitor inavolisib and COX-2 inhibitor celecoxib shows synergistic effects against colorectal cancer. This combination therapy potently suppresses tumor growth, particularly in PIK3CA-mutated models, offering a promising new therapeutic strategy.
Area of Science:
- Oncology
- Molecular Biology
- Pharmacology
Background:
- The PI3K/AKT/mTOR pathway is crucial for cancer cell survival and proliferation.
- Activating PIK3CA mutations are prevalent in colorectal cancer (CRC) and linked to increased COX-2 expression.
- Low-dose aspirin has shown survival benefits in CRC patients, suggesting potential synergy with PI3K inhibitors.
Purpose of the Study:
- To investigate the synergistic effects of combining a PI3Kα inhibitor (inavolisib) with a COX-2 inhibitor (celecoxib) in colorectal cancer.
- To evaluate the efficacy of this combination therapy in various colorectal cancer models, including cell lines and patient-derived organoids.
- To explore the impact of PIK3CA mutation status on treatment response.
Main Methods:
- Utilized human colorectal cancer cell lines (2D and 3D cultures) and patient-derived organoid models.
- Performed cell viability, colony formation, immunoblotting, and immunofluorescence assays.
- Assessed apoptosis using Annexin V and phosphatidylserine staining.
Main Results:
- Celecoxib and inavolisib demonstrated synergistic growth suppression in CRC cell lines and organoids, irrespective of PIK3CA mutation status.
- PIK3CA-mutated organoids showed more potent growth suppression compared to wild-type.
- Combination therapy decreased p-AKT expression and increased cPARP expression, indicating pathway inhibition and apoptosis induction.
- Apoptosis assays showed a significant increase in apoptotic cells with combination therapy, particularly in PIK3CA-mutated cell lines.
Conclusions:
- The combination of celecoxib and inavolisib exhibits synergistic anti-cancer effects in colorectal cancer models.
- PIK3CA mutation status influences drug efficacy in patient-derived organoids but not in cell lines.
- Potential resistance mechanisms may involve MAPK/ERK pathway activation.
- This combination therapy represents a promising preclinical strategy for colorectal cancer treatment, especially in PIK3CA-mutated cases.
