| 1. |
- Semenas, Julius, 1987-
(författare)
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Targeted therapeutic strategies for prostate cancer treatment using novel lipid kinase inhibitors in combination with current drugs
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Prostate cancer (PCa) is one of the most common cancer types and the fifth cancer-related cause of death among Western world men. The sex steroid hormone, androgen and androgen receptor (AR) play important roles in PCa progression. Herewith, androgen deprivation therapy (ADT) is used as a regimen for PCa, but inevitably leads to development of castration-resistant PCa (CRPC) and distant metastasis. No effective treatment for metastatic PCa currently exists. Furthermore, it remains poorly understood whether and how the steroid hormone signaling in cooperation with multiple pathways that control proliferation, survival and invasion of cancer cells may contribute to metastatic dissemination and growth.The aims of my PhD thesis focused on: (i) studying the clinical importance of estrogen- and androgen-related signaling pathways in promoting homing and metastatic growth of PCa cells in bone, (ii) gaining deeper understanding of the underlying mechanisms that facilitate PCa metastasis and treatment resistance, with focus on phosphatidylinositol-4-phosphate 5-kinase type-1 alpha (PIP5K1α), estrogen- and androgen receptor signaling, (iii) testing and characterizing the therapeutic potential of PIP5K1α inhibitor in combination with anti-estrogen or anti-androgen agents to improve treatment and overcome treatment resistance in CRPC.In my thesis work we have shown that key biomarker genes exhibited unique expression profiles and signatures in PCa subtypes within large patient cohorts. Alterations in androgen- and estrogen-related biomarkers and PIP5K1α/Akt pathways were associated with poor patient outcome. We further discovered that CRPC cells and cancer stem-like cells utilized estrogen-associated factors including aromatase and estrogen receptor alpha (ERα), as well as cyclin A1, a key cell cycle regulator, to gain proliferative advantage, and to survive and metastasize to distant organs.We found that the interaction between PIP5K1α and AR splice variant AR-V7 contributed to enzalutamide resistance. In series of in vivo treatment experiments using tumor xenograft mice, we demonstrated that ISA-2011B alone or in combination with enzalutamide had great therapeutic potential to suppress growth of tumors that had elevated levels of PI3K/Akt and AR-V7, and that were resistant to enzalutamide monotherapy.We further showed that combination treatment using tamoxifen together with ISA-2011B selectively blocked elevated ERα/cyclin D1 and PIP5K1α/Akt, leading to tumor regression and had superior inhibitory effect over monotherapy in xenograft mice.My studies therefore suggest that steroid hormone receptors, PIP5K1α signaling cascade and multiple cellular pathways cooperatively promote PCa progression. Taken together, the reported findings are the first to suggest a new therapeutic potential to inhibit or utilize the mechanisms related to ERα and PIP5K1α/Akt network, and provide a new therapeutic strategy to treat castration-resistant ER-positive subtype of tumors with metastatic potential.
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| 2. |
- Wang, Tianyan, 1983-
(författare)
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Utility of novel drug targets for treatment of metastatic cancer
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Metastasis is the leading cause of cancer death because of a lack of early diagnosis tools and efficient treatment drugs. The lipid kinase phosphatidylinositol 4-phosphate 5 kinase (PIP5K1α) has been shown to play a vital role in the PI3K/AKT and KRAS signaling pathways. My PhD work, therefore, aims: (i) to study the role of PIP5K1α as a potential target for cancer treatment and the utility of its inhibitor ISA-2011B for the treatment of castration-resistant prostate cancer (CRPC) and pancreatic cancer, (ii) to establish genetically engineered mouse models and murine syngeneic models to recapitulate pancreatic cancer progression and test targeted anticancer drugs, (iii) to utilize the state-of-the-art molecularly imprinting technique for cancer biomarker detection.My thesis work has shown a clear inhibitory effect of ISA-2011B on human CRPC cell lines C4-2, DU145, and PC-3. The siRNA-mediated downregulation of PIP5K1α and ISA-2011B treatments both showed inhibition of the in vitro growth in all three cell lines. The PC-3 cell and its xenograft tumor can be inhibited by tamoxifen or ISA-2011B treatment alone, and a combination treatment from both compounds can selectively block the ERα and PIP5K1α/AKT network. The results, therefore, suggest that it is possible to treat CRPC by targeting PIP5K1α/AKT and ERα pathways.We established the KPC [Krastm4Tyj Trp53tm1Brn Tg(Pdx1-Cre/Esr1*)] mouse model, in which spontaneous pancreatic ductal adenocarcinoma (PDAC) develops under tamoxifen induction. Three PDAC cell lines bearing KRASG12D and P53 mutations from spontaneous tumors were established and characterized. ISA-2011B in vitro treatment on those cell lines showed that KRASG12D and pErk were significantly decreased in at least one of the cell lines. It suggests that PIP5K1α is a potential target, and its inhibitor ISA-2011B is a promising drug for treating KRAS-mutated PDAC. The syngeneic PDAC model was also prepared by subcutaneous injection of the three cell lines back into the KPC mice, which will be used as an in vivo model to study the function of PIP5K1α in PDAC further.We developed molecularly imprinted polymers (MIPs) for the potential biomarker Neu5Acα2-6GalNAcα-O-Ser/Thr (STn), as well as the non-imprinted polymers(NIPs) as a control. We identified human PDAC cell lines CFPAC-1 and BxPC-3 are STn-positive and -negative cells, respectively. Although STn-MIPs have a higher affinity than NIPs to both cancer cell lines, STn-MIPs cannot differentiate the STn-positive CFPAC-1 cells from the STn-negative BxPC-3 cells. It remains challenging to apply MIPs to detect biological molecules.Our data provide a novel therapeutic strategy to treat advanced cancers such as CRPC and KRAS-mutated PDAC by targeting PIP5K1α-associate PI3K/AKT and/or KRAS signaling pathways.
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| 3. |
- Edin, Sofia, 1977-
(författare)
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Calmodulin mediated regulation of NF-kappaB in lymphocytes
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- NF-κB transcription factors are regulators of a wide spectrum of genes involved in immune responses and inflammation as well as cellular proliferation and survival. Transcriptionally competent NF-κB dimers are retained in the cytoplasm of resting cells by binding to inhibitors of NF-κB (IκBs). Stimuli that activate NF-κB converge on the activation of the IκB kinase (IKK), resulting in phosphorylation and subsequent proteasomal degradation of IκB. This releases functional NF-κB dimers that rapidly move to the nucleus where they regulate transcription of NF-κB-dependent target genes. The study of signalling to NF-κB from T and B lymphocyte antigen receptors is a field of intense investigation, and much attention is focused on the complex of the molecular scaffolding proteins Carma1, Bcl10 and MALT1. Together, these are crucial for the organisation of a structure beneath the activated receptor, termed the immunological synapse. IKK is recruited to this structure and becomes activated, subsequently leading to activation of NF-κB. Calcium (Ca2+) is a ubiquitous intracellular messenger that is involved in the regulation of numerous aspects of cellular function, including transcription. NF-κB activity is known to be regulated by changes in intracellular Ca2+ levels, such as those created by antigen receptor activation, but the mechanisms are to a large extent undefined. Ca2+ signals in cells are transmitted predominantly by the ubiquitous Ca2+ sensor protein calmodulin (CaM). Signalling that increases the intracellular Ca2+ concentration leads to binding of Ca2+ to CaM, which changes its structure, thereby allowing it to interact with a new range of target proteins. The studies of NF-κB signalling in lymphocytes presented here reveal that CaM is involved, both directly and indirectly, in the regulation of NF-κB. CaM was found to interact directly and in a Ca2+-dependent manner with the NF-κB proteins RelA and c-Rel after their signal-induced release from IκB. The interaction of CaM with c-Rel, but not RelA, was found to be inhibitory for its nuclear accumulation and transcriptional activity on Ca2+-regulated IL-2 and GM-CSF promoters; thus, CaM binding was found to differentially regulate c-Rel and RelA in lymphocytes. CaM was also shown to interact directly and in a Ca2+-dependent manner with Bcl10. The interaction was mapped to the Carma1-interacting CARD domain of Bcl10 and was found to have a negative effect on the ability of Bcl10 to bind to Carma1. Binding of CaM to Bcl10 also had a negative effect on activation of NF-κB after T cell receptor stimulation, since a point mutant of Bcl10 with reduced binding to CaM showed increased activation of an NF-κB reporter in Jurkat T cells, which was further enhanced by TCR-activating stimuli. In addition, CaM was found to positively regulate NF-κB activation indirectly through CaM-dependent kinase II (CaMKII). Inhibitors of CaM and CaMKII were shown to inhibit IκBα degradation in lymphocytes induced by phorbol ester or T cell receptor stimulation. The actions of CaMKII were mapped to a point upstream of IKK activation and further studies revealed that CaMKII is recruited to the immunological synapse, where it inducibly interacts with and phosphorylates Bcl10 at multiple sites. Phosphorylation of Bcl10 by CaMKII was shown to be important for the ability of Bcl10 to activate NF-κB, since mutation of the phosphorylation sites of Bcl10 inhibited Bcl10-induced transcriptional activity of NF-κB, in part by preventing signalinduced ubiquitination and degradation of Bcl10.
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| 4. |
- Hauser, Jannek, 1981-
(författare)
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Regulation of B cell development by antigen receptors
- 2011
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The developmental processes of lymphopoiesis generate mature B lymphocytes from hematopoietic stem cells through increasingly restricted intermediates. Networks of transcription factors regulate these cell fate choices and are composed of both ubiquitously expressed and B lineage-specific factors. E-protein transcription factors are encoded by the three genes E2A, E2-2 (SEF2-1), and HEB. The E2A gene is required for B cell development and encodes the alternatively spliced proteins E12 and E47. During B lymphocyte development, the cells have to pass several checkpoints verifying the functionality of their antigen receptors. Early in the development, the expression of a pre-B cell receptor (pre-BCR) with membrane-bound immunoglobulin (Ig) heavy chain protein associated with surrogate light chain (SLC) proteins is a critical checkpoint that monitors for functional Ig heavy chain rearrangement. Signaling from the pre-BCR induces survival and a limited clonal expansion. Here it is shown that pre-BCR signaling rapidly down-regulates the SLCs l5 and VpreB and also the co-receptor CD19. Ca2+ signaling and E2A were shown to be essential for this regulation. E2A mutated in its binding site for the Ca2+ sensor protein calmodulin (CaM), and thus with CaM-resistant DNA binding, makes l5, VpreB and CD19 expression resistant to the inhibition following pre-BCR stimulation. Thus, Ca2+ down-regulates SLC and CD19 gene expression upon pre-BCR stimulation through inhibition of E2A by Ca2+/CaM. A general negative feedback regulation of the pre-BCR proteins as well as many co-receptors and proteins in signal pathways from the receptor was also shown. After the ordered recombination of Ig heavy chain gene segments, also Ig light chain gene segments are recombined together to create antibody diversity. The recombinations are orchestrated by the recombination activating gene (RAG) enzymes, other enzymes that cleave/mutate/assemble DNA of the Ig loci, and the transcription factor Pax5. A key feature of the immune system is the concept that one lymphocyte has only one antigen specificity that can be selected for or against. This requires that only one of the alleles of genes for Ig chains is made functional. The mechanism of this allelic exclusion has however been an enigma. Here pre-BCR signaling was shown to down-regulate several components of the recombination machinery including RAG1 and RAG2 through CaM inhibition of E2A. Furthermore, E2A, Pax5 and the RAGs were shown to be in a complex bound to key sequences on the IgH gene before pre-BCR stimulation and instead bound to CaM after this stimulation. Thus, the recombination complex is directly released through CaM inhibition of E2A. Upon encountering antigens, B cells must adapt to produce a highly specific and potent antibody response. Somatic hypermutation (SH), which introduces point mutations in the variable regions of Ig genes, can increase the affinity for antigen, and antibody effector functions can be altered by class switch recombination (CSR), which changes the expressed constant region exons. Activation-induced cytidine deaminase (AID) is the mutagenic antibody diversification enzyme that is essential for both SH and CSR. The AID enzyme has to be tightly controlled as it is a powerful mutagen. BCR signaling, which signals that good antibody affinity has been reached, was shown to inhibit AID gene expression through CaM inhibition of E2A. SH increases the antigen binding strength by many orders of magnitude. Each round of SH leads to one or a few mutations, followed by selection for increased affinity. Thus, BCR signaling has to enable selection for successive improvements in antibodies (Ab) over an extremely broad range of affinities. Here the BCR is shown to be subject to general negative feedback regulation of the receptor proteins as well as many co-receptors and proteins in signal pathways from the receptor. Thus, the BCR can down-regulate itself to enable sensitive detection of successive improvements in antigen affinity. Furthermore, the feedback inhibition of the BCR signalosome and most of its protein, and most other gene regulations by BCR stimulation, is through inhibition of E2A by Ca2+/CaM. Differentiation to Ab-secreting plasmablasts and plasma cells is antigen-driven. The interaction of antigen with the membrane-bound Ab of the BCR is critical in determining which clones enter the plasma cell response. Genome-wide analysis showed that differentiation of B cells to Ab-secreting cell is induced by BCR stimulation through very fast regulatory events, and induction of IRF-4 and down-regulation of Pax5, Bcl-6, MITF, Ets-1, Fli-1 and Spi-B gene expressions were identified as immediate early events. Ca2+ signaling through CaM inhibition of E2A was essential for these rapid down-regulations of immediate early genes after BCR stimulation in initiation of plasma cell differentiation.
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| 5. |
- Oruganti, Sreenivasa Rao, 1981-
(författare)
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Regulation of activation of NF-κB by Calmodulin in T-lymphocytes
- 2011
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Nuclear factor kappa B (NF-kB) is a widely expressed family of transcription factors that are involved in a diverse number of processes. These include inflammation or differentiation, survival or apoptosis, and proliferation or cell cycle arrest. NF-kB is usually associated with inhibitory kB proteins (IkB), which mask the nuclear localisation sequence (NLS) of NF-kB and renders it in the cytoplasm. Various stimuli result in the activation of the I kappa B kinase (IKK) protein complex, which phosphorylates IκB proteins and thereby marks them for degradation by the ubiquitin-proteasome pathway. Thereby NF-kB enters the nucleus and acts on its target genes. The study of T- and B-lymphocyte antigen receptor signalling to NF-kB is a field of intense investigation, with much attention being focused on the molecular scaffolding proteins Carma1, Bcl10 and MALT1 and their post-translational modifications. These have been shown to be crucial for the organization of the immunological synapse structure under the activated receptor, to which IKK is recruited and becomes activated, which subsequently leads to the activation of NF-kB. T cell receptor (TCR) activation results in a rapid increase in the intracellular Ca2+ level and NF-kB activation is known to be regulated by those increases, but the mechanisms have remained unclear. Calmodulin (CaM) is a calcium sensory protein that responds to increases in intracellular Ca2+ levels. When CaM binds Ca2+ ions, it leads to structural changes that directly as well as indirectly, through CaM dependent kinases (CaMKs), phosphatases and other enzymes, alters a variety of cellular processes, among them transcriptional regulation. Here CaM is shown to interact directly with Bcl10 in a Ca2+ dependent manner. Increases in the intracellular Ca2+ level are shown to induce the proximity of Bcl10 and CaM in vivo. Carma1 associates with Bcl10 through a CARD-CARD domain interaction that is known to be crucial for TCR signalling to NF-kB. The interaction of CaM with Bcl10 was mapped to the CARD domain and was shown to be a negative regulator for the Bcl10-Carma1 interaction. Inhibition of the CaM interaction by a point mutation within the CaM binding site of Bcl10 results in decreased binding of CaM to Bcl10 in vivo, as well as an increased ability of Bcl10 to induce NF-kB transcriptional activity, which is further enhanced by TCR activating stimuli. NF-kB activation is also shown here to be regulated by CaM indirectly through actions of CaMKII. The CaMKII is recruited to the immunological synapse where it interacts with Bcl10 in an inducible fashion and phosphorylates Bcl10. Phosphorylations of Bcl10 by CaMKII are shown to be important for the ability of Bcl10 to induce NF-κB transcriptional activity. Upon mutation of its most important CaMKII site, Bcl10 fails to activate an NF-kB reporter and an NF-kB target gene (IL-2). This mutated Bcl10 also fails to induce activating phosphorylations of IKKa/b and the kinase JNK2 but not JNK1. Furthermore, phosphorylation of Bcl10 by CaMKII regulates the interactions within the important Carma1, Bcl10, Malt1 signaling complex and the essential signal induced ubiquitinations of Bcl10 and IKKg. Phosphorylation of IKK by TAK1 is also regulated by CaMKII, and serine 82 is a putative CaMKII target site of TAK1 that appears to be important for IκBα degradation. In summary, this thesis explores that not only NF-kB but also CaM is a double-edged sword, since the multi-functional NF-kB family of transcription factors is regulated by CaM both negatively and positively.
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| 6. |
- Antonsson, Åsa, 1972-
(författare)
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Regulation of NF-κB by Calmodulin
- 2003
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Cells experience numerous external signals which they must respond to. Such signals arriving at the cell surface are transduced via various signal transduction pathways and often ultimately result in regulation of transcription. NF-κB is a family of transcription factors involved in the regulation of genes important for processes such as immune and inflammatory responses, cell growth, development and cell survival. NF-κB proteins are normally kept inactive in the cytoplasm due to masking of their nuclear localisation signal (NLS) by inhibitory IκB proteins. A large number of stimuli lead to the activation of IκB-kinase (IKK). Active IKK phosphorylates IκB and thereby labels it for ubiquitination and, subsequently, degradation by the proteasome. Liberated NF-κB enters the nucleus, where it takes part in the regulation of its target genes.Calmodulin (CaM) is a ubiquitous Ca2+-binding protein which is considered to be the predominant intracellular Ca2+ sensor. CaM plays a major role in the Ca2+-dependent regulation of a wide variety of cellular processes, including transcription. CaM regulates transcription both indirectly through CaM-dependent kinases and phosphatases and directly through interaction with transcription factors.CaM was found to bind directly and in a Ca2+-dependent fashion to the two NF-κB family members c-Rel and RelA. The CaM-NF-κB interactions were strongly enhanced by NF-κB activating stimuli and this enhancement was blocked by the addition of IκB, suggesting that c-Rel and RelA can bind CaM after their signal-induced release from IκB. Compared to wild-type c-Rel, CaM binding-deficient mutants were shown to exhibit an increased nuclear accumulation and transcriptional activity on Ca2+-regulated cytokine promoters. The results suggest that CaM can inhibit transport of c-Rel, but not of RelA, to the nucleus and thereby differentially regulate the activation of NF-κB proteins following cell stimulation. CaM was also found to affect NF-κB activity indirectly through the action of a CaM-dependent kinase (CaMK). Studies of the events leading to IκBα phosphorylation revealed that CaM and CaMKII inhibitors blocked phorbol ester induced activation of IKK. Furthermore, CaM and CaMKII inhibitors also blocked T cell receptor/CD3 induced IκBα degradation, and expression of an inhibitor-resistant derivative of the γ isoform of CaMKII caused the inhibitors lose their effect on phorbol ester induced IκBα degradation. Finally, expression of a constitutively active CaMKII resulted in the activation of NF-κB. These results identify CaMKII as a mediator of IKK activation, specifically in response to T cell receptor/CD3 and phorbol ester stimulation.In conclusion, this thesis describes the identification of CaM as a dual regulator of NF-κB proteins, acting both directly and indirectly to affect the activity of this family of transcription factors.
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| 7. |
- Flodbring Larsson, Per, et al.
(författare)
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FcγRIIIa receptor interacts with androgen receptor and PIP5K1α to promote growth and metastasis of prostate cancer
- 2022
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Ingår i: Molecular Oncology. - : John Wiley & Sons. - 1574-7891 .- 1878-0261.
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Tidskriftsartikel (refereegranskat)abstract
- Low-affinity immunoglobulin gamma Fc region receptor III-A (FcγRIIIa) is a cell surface protein that belongs to a family of Fc receptors that facilitate the protective function of the immune system against pathogens. However, the role of FcγRIIIa in prostate cancer (PCa) progression remained unknown. In this study, we found that FcγRIIIa expression was present in PCa cells and its level was significantly higher in metastatic lesions than in primary tumors from the PCa cohort (P = 0.006). PCa patients with an elevated level of FcγRIIIa expression had poorer biochemical recurrence (BCR)-free survival compared with those with lower FcγRIIIa expression, suggesting that FcγRIIIa is of clinical importance in PCa. We demonstrated that overexpression of FcγRIIIa increased the proliferative ability of PCa cell line C4-2 cells, which was accompanied by the upregulation of androgen receptor (AR) and phosphatidylinositol-4-phosphate 5-kinase alpha (PIP5Kα), which are the key players in controlling PCa progression. Conversely, targeted inhibition of FcγRIIIa via siRNA-mediated knockdown or using its inhibitory antibody suppressed growth of xenograft PC-3 and PC-3M prostate tumors and reduced distant metastasis in xenograft mouse models. We further showed that elevated expression of AR enhanced FcγRIIIa expression, whereas inhibition of AR activity using enzalutamide led to a significant downregulation of FcγRIIIa protein expression. Similarly, inhibition of PIP5K1α decreased FcγRIIIa expression in PCa cells. FcγRIIIa physically interacted with PIP5K1α and AR via formation of protein-protein complexes, suggesting that FcγRIIIa is functionally associated with AR and PIP5K1α in PCa cells. Our study identified FcγRIIIa as an important factor in promoting PCa growth and invasion. Further, the elevated activation of FcγRIII and AR and PIP5K1α pathways may cooperatively promote PCa growth and invasion. Thus, FcγRIIIa may serve as a potential new target for improved treatment of metastatic and castration-resistant PCa.
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| 8. |
- Karlsson, Richard, et al.
(författare)
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Establishment of Prostate Tumor Growth and Metastasis Is Supported by Bone Marrow Cells and Is Mediated by PIP5K1α Lipid Kinase
- 2020
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Ingår i: Cancers. - : MDPI. - 2072-6694. ; 12:9
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Tidskriftsartikel (refereegranskat)abstract
- Cancer cells facilitate growth and metastasis by using multiple signals from the cancer-associated microenvironment. However, it remains poorly understood whether prostate cancer (PCa) cells may recruit and utilize bone marrow cells for their growth and survival. Furthermore, the regulatory mechanisms underlying interactions between PCa cells and bone marrow cells are obscure. In this study, we isolated bone marrow cells that mainly constituted populations that were positive for CD11b and Gr1 antigens from xenograft PC-3 tumor tissues from athymic nu/nu mice. We found that the tumor-infiltrated cells alone were unable to form tumor spheroids, even with increased amounts and time. By contrast, the tumor-infiltrated cells together with PCa cells formed large numbers of tumor spheroids compared with PCa cells alone. We further utilized xenograft athymic nu/nu mice bearing bone metastatic lesions. We demonstrated that PCa cells were unable to survive and give rise to colony-forming units (CFUs) in media that were used for hematopoietic cell colony-formation unit (CFU) assays. By contrast, PC-3M cells survived when bone marrow cells were present and gave rise to CFUs. Our results showed that PCa cells required bone marrow cells to support their growth and survival and establish bone metastasis in the host environment. We showed that PCa cells that were treated with either siRNA for PIP5K1α or its specific inhibitor, ISA-2011B, were unable to survive and produce tumor spheroids, together with bone marrow cells. Given that the elevated expression of PIP5K1α was specific for PCa cells and was associated with the induced expression of VEGF receptor 2 in PCa cells, our findings suggest that cancer cells may utilize PIP5K1α-mediated receptor signaling to recruit growth factors and ligands from the bone marrow-derived cells. Taken together, our study suggests a new mechanism that enables PCa cells to gain proliferative and invasive advantages within their associated host microenvironment. Therapeutic interventions using PIP5K1α inhibitors may not only inhibit tumor invasion and metastasis but also enhance the host immune system.
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| 9. |
- Semenas, Julius, et al.
(författare)
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Targeted inhibition of ERα signaling and PIP5K1α/Akt pathways in castration‐resistant prostate cancer
- 2021
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Ingår i: Molecular Oncology. - : John Wiley & Sons. - 1574-7891 .- 1878-0261. ; 15:4, s. 968-986
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Tidskriftsartikel (refereegranskat)abstract
- Selective ERα modulator, tamoxifen, is well tolerated in a heavily pretreated castration‐resistant prostate cancer (PCa) patient cohort. However, its targeted gene network and whether expression of intratumor ERα due to androgen‐deprivation therapy (ADT) may play a role in PCa progression is unknown. In this study, we examined the inhibitory effect of tamoxifen on castration‐resistant PCa in vitro and in vivo. We found that tamoxifen is a potent compound that induced a high degree of apoptosis and significantly suppressed growth of xenograft tumors in mice, at a degree comparable to ISA‐2011B, an inhibitor of PIP5K1α that acts upstream of PI3K/AKT survival signaling pathway. Moreover, depletion of tumor‐associated macrophages using clodronate in combination with tamoxifen increased inhibitory effect of tamoxifen on aggressive prostate tumors. We showed that both tamoxifen and ISA‐2011B exert their on‐target effects on prostate cancer cells by targeting cyclin D1 and PIP5K1α/AKT network and the interlinked estrogen signaling. Combination treatment using tamoxifen together with ISA‐2011B resulted in tumor regression and had superior inhibitory effect compared with that of tamoxifen or ISA‐2011B alone. We have identified sets of genes that are specifically targeted by tamoxifen, ISA‐2011B or combination of both agents by RNA‐seq. We discovered that alterations in unique gene signatures, in particular estrogen‐related marker genes are associated with poor patient disease‐free survival. We further showed that ERα interacted with PIP5K1α through formation of protein complexes in the nucleus, suggesting a functional link. Our finding is the first to suggest a new therapeutic potential to inhibit or utilize the mechanisms related to ERα, PIP5K1α/AKT network and MMP9/VEGF signaling axis, providing a strategy to treat castration‐resistant ER‐positive subtype of prostate cancer tumors with metastatic potential.
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| 10. |
- Wang, Tianyan, et al.
(författare)
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PIP5K1α is Required for Promoting Tumor Progression in Castration-Resistant Prostate Cancer
- 2022
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Ingår i: Frontiers in Cell and Developmental Biology. - : Frontiers Media S.A.. - 2296-634X. ; 10
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Tidskriftsartikel (refereegranskat)abstract
- PIP5K1α has emerged as a promising drug target for the treatment of castration-resistant prostate cancer (CRPC), as it acts upstream of the PI3K/AKT signaling pathway to promote prostate cancer (PCa) growth, survival and invasion. However, little is known of the molecular actions of PIP5K1α in this process. Here, we show that siRNA-mediated knockdown of PIP5K1α and blockade of PIP5K1α action using its small molecule inhibitor ISA-2011B suppress growth and invasion of CRPC cells. We demonstrate that targeted deletion of the N-terminal domain of PIP5K1α in CRPC cells results in reduced growth and migratory ability of cancer cells. Further, the xenograft tumors lacking the N-terminal domain of PIP5K1α exhibited reduced tumor growth and aggressiveness in xenograft mice as compared to that of controls. The N-terminal domain of PIP5K1α is required for regulation of mRNA expression and protein stability of PIP5K1α. This suggests that the expression and oncogenic activity of PIP5K1α are in part dependent on its N-terminal domain. We further show that PIP5K1α acts as an upstream regulator of the androgen receptor (AR) and AR target genes including CDK1 and MMP9 that are key factors promoting growth, survival and invasion of PCa cells. ISA-2011B exhibited a significant inhibitory effect on AR target genes including CDK1 and MMP9 in CRPC cells with wild-type PIP5K1α and in CRPC cells lacking the N-terminal domain of PIP5K1α. These results indicate that the growth of PIP5K1α-dependent tumors is in part dependent on the integrity of the N-terminal sequence of this kinase. Our study identifies a novel functional mechanism involving PIP5K1α, confirming that PIP5K1α is an intriguing target for cancer treatment, especially for treatment of CRPC.
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