RB1 expression and targeting by CDK4/6 inhibitors in small cell lung cancer
Ontology highlight
ABSTRACT:
PROVIDER: PRJNA899882 | ENA |
REPOSITORIES: ENA
Similar Datasets
Project description:The canonical model of small cell lung cancer (SCLC) depicts tumors arising from dual inactivation of TP53 and RB1. However, many genomic studies have persistently identified tumors with no RB1 mutations. Here, we examined RB1 protein expression and function in SCLC. RB1 expression was examined by immunohistochemical analysis of 62 human SCLC tumors. These studies showed that ~14% of SCLC tumors expressed abundant RB1 protein, which is associated with neuroendocrine (NE) gene expression and is enriched in YAP1 expression, but no other lineage proteins that stratify SCLC. SCLC cells and xenograft tumors with RB1 protein expression were sensitive to growth inhibition by the CDK4/6 inhibitor palbociclib, and this inhibition was shown to be dependent on RB1 expression by CRISPR knockout. Furthermore, a patient with biopsy-validated wt RB1 SCLC who received the CDK4/6 inhibitor abemaciclib demonstrated a dramatic decrease in mutant TP53 ctDNA allelic fraction from 62.1% to 0.4% and decreased tumor mass on CT scans. Importantly, immunohistochemistry of the diagnostic biopsy specimen showed RB1 positivity. Finally, we identified a transcriptomics-based RB1 loss-of-function signature that discriminates between SCLC cells with or without RB1 protein expression and validated it in the patient who was responsive to abemaciclib, suggesting its potential use to predict CDK4/6 inhibitor response in SCLC patients. Our study demonstrates that RB1 protein is an actionable target in a subgroup of SCLC, a cancer that exhibits no currently targetable mutations.
2022-11-14 | GSE217646 | GEO
Project description:The efficacy of immunotherapy in prostate cancer is not satisfactory due to the “cold” tumor microenvironment and the paucity of neoantigens. The STING-TBK1-IRF3 signaling axis as core molecules of the innate immune system is increasingly recognized as a candidate target for cancer immunotherapy. Previou studies reported that CDK4/6 inhibitors induced DNA damage to activate the cGAS-STING pathway. However, the underlying mechanisms of how CDK4/6 inactivated the cGAS-STING pathway are still elusive. Here we revealed that treatment with CDK4/6 inhibitors enhance the anti-tumor effect of STING agonists in prostate cancer cells. Mechanically, CDK4/6 phosphorylated TBK1 at S527 to inactive the STING signaling pathway independent of RB1 in prostate cancer cell. Then, we also found that CDK4/6 phosphorylated RB1 at S249/T252 to induce the interaction of RB1 with TBK1 and diminish the phosphorylation of TBK1 at S172, which also suppresses the activation of the STING pathway. Collectively, we found that CDK4/6 inhibits the STING/TBK1/IRF3 axis through RB1-dependent and RB1-independent pathways in prostate cancer cells. These insights provide the novel evidence for CDK4/6 suppressing the innate immune response of prostate cancer.
2024-06-01 | GSE268848 | GEO
Project description:The efficacy of immunotherapy in prostate cancer is not satisfactory due to the heterogeneity of this cancer, the “cold” tumor microenvironment and the paucity of neoantigens. The STING-TBK1-IRF3 signaling axis as core molecules of the innate immune system is increasingly recognized as a candidate target for cancer immunotherapy. Inhibition of CDK4/6 has been reported to r increase T-cell activation to enhance antitumor immunity. However, little is known about the relationship between CDK4/6 and innate immune-related STING signaling. In this study, we revealed that combination treatment with CDK4/6 inhibitors and STING agonists is significantly more effective than treatment with STING agonists alone in eliminating prostate cancer cells. Then, we demonstrated that CDK4/6 phosphorylate TBK1 at S527 to inactive the STING signaling pathway independent of RB1 in prostate cancer cell. On the other hand, CDK4/6 phosphorylate RB1 at S249/T252 to promote the interaction of RB1 with TBK1 and diminish the phosphorylation of TBK1 at S172, which also suppresses the activation of the STING pathway. Collectively, we found that CDK4/6 inhibits the STING/TBK1/IRF3 axis through RB1-dependent and RB1-independent pathways and elucidated the detailed mechanism. These insights lay a solid foundation for the synergistic application of CDK4/6 inhibitors with STING activators in prostate cancer patients.
2024-05-21 | GSE248019 | GEO
Project description:Resistance to neoadjuvant chemotherapy is associated tumor recurrence of locally advanced rectal cancer (LARC), which remains an unmet demand to exploit potential therapeutic strategies to improve clinical outcomes. Here we demonstrated that aberrant activation of cell cycle pathways is correlated with resistance to neoadjuvant chemotherapy in LARC. A combinatorial drug screening of 130 kinase inhibitors targeting cell cycle regulators with oxaliplatin identified that CDK4/6 inhibitors synergistically enhanced anti-tumor effects of oxaliplatin both intrinsic and acquired chemo-resistant colon cancer cells. Functional studies in both in vitro and in vivo models showed that CDK4/6 inhibitors significantly increased sensitivity to oxaliplatin. Integrative transcriptomic and chromatin profiling analysis revealed that CDK4/6 inhibitors induced DNA repair defects to enhance sensitivity of oxaliplatin through epigenetically suppression of DNA repair related genes. Mechanistically, CDK4/6 inhibition impairs DNA damage repair through a previously unrecognized RB1/TEAD4/HDAC1 co-repressor complex which contributes to the resistance to neoadjuvant chemotherapy in LARC. Together, our work revealed an important role of CDK4/6 pathway in LARC patients with neoadjuvant chemotherapy, suggesting that targeting CDK4/6 could provide a potentially effective treatment strategy for LARC.
2024-02-26 | GSE205035 | GEO
Project description:Resistance to neoadjuvant chemotherapy is associated tumor recurrence of locally advanced rectal cancer (LARC), which remains an unmet demand to exploit potential therapeutic strategies to improve clinical outcomes. Here we demonstrated that aberrant activation of cell cycle pathways is correlated with resistance to neoadjuvant chemotherapy in LARC. A combinatorial drug screening of 130 kinase inhibitors targeting cell cycle regulators with oxaliplatin identified that CDK4/6 inhibitors synergistically enhanced anti-tumor effects of oxaliplatin both intrinsic and acquired chemo-resistant colon cancer cells. Functional studies in both in vitro and in vivo models showed that CDK4/6 inhibitors significantly increased sensitivity to oxaliplatin. Integrative transcriptomic and chromatin profiling analysis revealed that CDK4/6 inhibitors induced DNA repair defects to enhance sensitivity of oxaliplatin through epigenetically suppression of DNA repair related genes. Mechanistically, CDK4/6 inhibition impairs DNA damage repair through a previously unrecognized RB1/TEAD4/HDAC1 co-repressor complex which contributes to the resistance to neoadjuvant chemotherapy in LARC. Together, our work revealed an important role of CDK4/6 pathway in LARC patients with neoadjuvant chemotherapy, suggesting that targeting CDK4/6 could provide a potentially effective treatment strategy for LARC.
2024-02-26 | GSE207521 | GEO
Project description:Background: Advanced gastrointestinal stromal tumor (GIST) is characterized by genomic perturbations of key cell cycle regulators. Oncogenic activation of CDK4/6 results in RB1 inactivation and cell cycle progression. Given that single-agent CDK4/6 inhibitor therapy failed to show clinical activity in advanced GIST, we evaluated strategies for maximizing response to therapeutic CDK4/6 inhibition. Methods: Targeted next-generation sequencing and multiplexed protein imaging were used to detect cell cycle regulator aberrations in GIST clinical samples. The impact of inhibitors of CDK2, CDK4, and CDK2/4/6 was determined through cell proliferation and protein detection assays. CDK-inhibitor resistance mechanisms were characterized in GIST cell lines after long-term exposure. Results: We identify recurrent genomic aberrations in cell cycle regulators causing co-activation of the CDK2 and CDK4/6 pathways in clinical GIST samples. Therapeutic co-targeting of CDK2 and CDK4/6 is synergistic in GIST cell lines with intact RB1, through inhibition of RB1 hyperphosphorylation and cell proliferation. Moreover, RB1 inactivation and a novel oncogenic cyclin D1 resulting from an intragenic rearrangement (CCND1::chr11.g:70025223) are mechanisms of acquired CDK inhibitor resistance in GIST. Conclusions: These studies establish the biologic rationale for CDK2 and CDK4/6 co-inhibition as therapeutic strategy in patients with advanced GIST, including metastatic GIST progressing on tyrosine kinase inhibitors.
2022-11-01 | GSE206257 | GEO
Project description:CDK4/6 inhibitors (CDK4/6i) are effective in metastatic breast cancer, but they have been only modestly effective in most other tumor types. Here we show that tumors expressing low CDK6 rely on CDK4 function, and are exquisitely sensitive to CDK4/6i. In contrast, tumor cells expressing both CDK4 and CDK6 have increased reliance on CDK6 to ensure cell cycle progression. We discovered that CDK4/6i and CDK4/6 degraders potently bind and inhibit CDK6 selectively in tumors in which CDK6 is highly thermo-unstable and strongly associated with the HSP90/CDC37 complex. In contrast, CDK4/6i and CDK4/6 degraders are ineffective in antagonizing tumor cells expressing thermostable CDK6, due to their weaker binding to CDK6 in these cells. Thus, we uncover a general mechanism of intrinsic resistance to CDK4/6i and CDK4/6i-derived degraders and the need for novel inhibitors targeting the CDK4/6i-resistant, thermostable form of CDK6 for application as cancer therapeutics.
2022-02-16 | PXD023137 | Pride
Project description:Inactivating mutations in SMARCA4 (BRG1), a key SWI/SNF chromatin remodelling gene, underlie small cell carcinoma of the ovary, hypercalcemic type (SCCOHT). To reveal its druggable vulnerabilities, we perform kinase-focused RNAi screens and uncover that SMARCA4-deficient SCCOHT cells are highly sensitive to the inhibition of cyclin-dependent kinase 4/6 (CDK4/6). SMARCA4 loss causes profound downregulation of cyclin D1, which limits CDK4/6 kinase activity in SCCOHT cells and leads to in vitro and in vivo susceptibility to CDK4/6 inhibitors. SCCOHT patient tumors are deficient in cyclin D1 yet retain the retinoblastoma-proficient/p16INK4a-deficient profile associated with positive responses to CDK4/6 inhibitors. Thus, our findings indicate that CDK4/6 inhibitors, approved for a breast cancer subtype addicted to CDK4/6 activation, could be repurposed to treat SCCOHT. Moreover, our study suggests a novel paradigm whereby critically low oncogene levels, caused by loss of a driver tumor suppressor, may also be exploited therapeutically.
2019-02-04 | GSE120298 | GEO
Project description:Inactivating mutations in SMARCA4 (BRG1), a key SWI/SNF chromatin remodelling gene, underlie small cell carcinoma of the ovary, hypercalcemic type (SCCOHT). To reveal its druggable vulnerabilities, we perform kinase-focused RNAi screens and uncover that SMARCA4-deficient SCCOHT cells are highly sensitive to the inhibition of cyclin-dependent kinase 4/6 (CDK4/6). SMARCA4 loss causes profound downregulation of cyclin D1, which limits CDK4/6 kinase activity in SCCOHT cells and leads to in vitro and in vivo susceptibility to CDK4/6 inhibitors. SCCOHT patient tumors are deficient in cyclin D1 yet retain the retinoblastoma-proficient/p16INK4a-deficient profile associated with positive responses to CDK4/6 inhibitors. Thus, our findings indicate that CDK4/6 inhibitors, approved for a breast cancer subtype addicted to CDK4/6 activation, could be repurposed to treat SCCOHT. Moreover, our study suggests a novel paradigm whereby critically low oncogene levels, caused by loss of a driver tumor suppressor, may also be exploited therapeutically.
2019-02-04 | GSE120297 | GEO
Project description:Despite overall good prognosis associated to thyroid cancer, poorly differentiated carcinomas (PDTC) and anaplastic carcinomas (ATC) represent major clinical challenges. We have shown that the presence of active T172-phosphorylated CDK4 predicts sensitivity to CDK4/6 inhibitory drugs (CDK4/6i) including palbociclib. Here, CDK4 phosphorylation was detected in all well-differentiated thyoid carcinomas (n=29), 19/20 PDTC, 16/23 ATC, and 18/21 thyroid cancer cell lines including 11 ATC-derived ones. The cell lines lacking CDK4 phosphorylation were insensitive to CDK4/6i. RNA-sequencing and immunohistochemistry revealed that tumors and cell lines without phosphorylated CDK4 presented very high p16CDKN2A levels that were associated with proliferative activity. One of the main mechanisms of resistance to CDK4/6i is RB1 defects or inactivation. RB1 mutations were present in the 3 insensitive cell lines but were not found in 5 of the 7 tumors without phosphorylated CDK4. p16/KI67 immunohistochemistry and a previously developed 11-gene signature identified the likely insensitive tumors and cell lines lacking CDK4 phosphorylation. In cell lines, palbociclib synergized with dabrafenib/trametinib, completely and irreversibly arresting proliferation. The combined drugs prevented resistance mechanisms induced by palbociclib, most notably Cyclin E1-CDK2 activation and a paradoxical stabilization of phosphorylated CDK4 complexes. Our study supports the evaluation of CDK4/6i for ATC/PDTC treatment, including in combination with MEK/BRAF inhibitors.
2023-10-10 | GSE235468 | GEO