Search Results (4)

Intra-tumor heterogeneity (ITH) poses a major obstacle in cancer therapy. In colorectal cancer (CRC), mutations in the transforming growth factor-β/bone morphogenetic protein (TGF-β/BMP) pathway, especially in the SMAD4 gene, have been correlated with decreased overall survival and are suspected to modulate chemoresistance. We have previously shown that SMAD4^R361H is associated with differential drug response towards EGFR, MEK and PI3K inhibitors. Here, we analyzed the mechanistic role of SMAD4^R361H using oncoproteomics in CRISPR-engineered SMAD4^R361H and CRC patient-derived organoids (PD3D^®). Utilizing DigiWest^® multiplex protein profiling analysis, we confirmed a stronger response to MEK inhibition in organoids harboring SMAD4^R361H as compared to SMAD4^wt PD3D. After 24 h of incubation with 0.03 µM trametinib, we observed a more pronounced decrease in proliferation markers, such as cyclin B1 and aurora kinase A in SMAD4^R361H cells. Interestingly, there was no noticeable accumulation of caspases 3 and 9 in any organoid culture; however, there was a conspicuous trend in the accumulation of Bcl-xL in presence of SMAD4^R361H. To understand the underlying mechanism of such a discrepancy, we analyzed the protein levels and phosphorylation status of other SMADs, as SMAD4^R361H disrupts TGF-β/BMP signal transduction. Out of all SMADs, only SMAD5 showed significant changes in protein level and phosphorylation status in response to the treatment only in SMAD4^wt organoids. As previously published, BMP signaling promotes cancer cell proliferation and tumor growth. It is plausible to assume that functional loss of SMAD4 and thus loss of SMAD5 signaling renders the SMAD4^R361H subpopulation of cells more sensitive to MEK inhibitors. Loss of SMAD4 was previously shown to promote chemoresistance and was associated with a higher recurrence rate in colorectal cancer. The heterogenic landscape of mutated SMAD4 within the same tumor, in this light, can give rise to multi-drug resistant disease. Full article

In cancer, the complex interplay between tumor cells and the tumor microenvironment results in the modulation of signaling processes. By assessing the expression of a multitude of proteins and protein variants in cancer tissue, wide-ranging information on signaling pathway activation and the status of the immunological landscape is obtainable and may provide viable information on the treatment response. Archived breast cancer tissues from a cohort of 84 patients (no adjuvant therapy) were analyzed by high-throughput Western blotting, and the expression of 150 proteins covering central cancer pathways and immune cell markers was examined. By assessing CD8α, CD11c, CD16 and CD68 expression, immune cell infiltration was determined and revealed a strong correlation between event-free patient survival and the infiltration of immune cells. The presence of tumor-infiltrating lymphocytes was linked to the pronounced activation of the Jak/Stat signaling pathway and apoptotic processes. The elevated phosphorylation of PPARγ (pS112) in non-immune-infiltrated tumors suggests a novel immune evasion mechanism in breast cancer characterized by increased PPARγ phosphorylation. Multiplexed immune cell marker assessment and the protein profiling of tumor tissue provide functional signaling data facilitating breast cancer patient stratification. Full article

Background: In colorectal cancer (CRC), mutations of genes associated with the TGF-β/BMP signaling pathway, particularly affecting SMAD4, are known to correlate with decreased overall survival and it is assumed that this signaling axis plays a key role in chemoresistance. Methods: Using CRISPR technology on syngeneic patient-derived organoids (PDOs), we investigated the role of a loss-of-function of SMAD4 in sensitivity to MEK-inhibitors. CRISPR-engineered SMAD4^R361H PDOs were subjected to drug screening, RNA-Sequencing, and multiplex protein profiling (DigiWest^®). Initial observations were validated on an additional set of 62 PDOs with known mutational status. Results: We show that loss-of-function of SMAD4 renders PDOs sensitive to MEK-inhibitors. Multiomics analyses indicate that disruption of the BMP branch within the TGF-β/BMP pathway is the pivotal mechanism of increased drug sensitivity. Further investigation led to the identification of the SFAB-signature (SMAD4, FBXW7, ARID1A, or BMPR2), coherently predicting sensitivity towards MEK-inhibitors, independent of both RAS and BRAF status. Conclusion: We identified a novel mutational signature that reliably predicts sensitivity towards MEK-inhibitors, regardless of the RAS and BRAF status. This finding poses a significant step towards better-tailored cancer therapies guided by the use of molecular biomarkers. Full article

Non-invasive physical plasma (NIPP) is a novel therapeutic tool, currently being evaluated for the treatment of cancer and precancerous lesions in gynecology and other disciplines. Additionally, patients with cervical intraepithelial neoplasia (CIN) may benefit from NIPP treatment due to its non-invasive, side-effect-free, and tissue-sparing character. However, the molecular impact of in vivo NIPP treatment needs to be further investigated. For this purpose, usually only very small tissue biopsies are available after NIPP treatment. Here, we adapted DigiWest technology, a high-throughput bead-based Western blot, for the analysis of formalin-fixed paraffin-embedded (FFPE) cervical punch biopsies with a minimal sample amount. We investigated the molecular effects of NIPP treatment directly after (0 h) and 24 h after in vivo application. Results were compared to in vitro NIPP-treated human malignant cervical cells. NIPP effects were primarily based on an inhibitory impact on the cell cycle and cell growth factors. DigiWest technology was suitable for detailed protein profiling of small, primary FFPE biopsies. Full article