CITED2 attenuates macrophage recruitment concordant with the downregulation of CCL20 in breast cancer cells

Transcriptional co-activators: emerging roles in signaling pathways and potential therapeutic targets for diseases

Specific cell states in metazoans are established by the symphony of gene expression programs that necessitate intricate synergic interactions between transcription factors and the co-activators. Deregulation of these regulatory molecules is associated with cell state transitions, which in turn is accountable for diverse maladies, including developmental disorders, metabolic disorders, and most significantly, cancer. A decade back most transcription factors, the key enablers of disease development, were historically viewed as 'undruggable'; however, in the intervening years, a wealth of literature validated that they can be targeted indirectly through transcriptional co-activators, their confederates in various physiological and molecular processes. These co-activators, along with transcription factors, have the ability to initiate and modulate transcription of diverse genes necessary for normal physiological functions, whereby, deregulation of such interactions may foster tissue-specific disease phenotype. Hence, it is essential to analyze how these co-activators modulate specific multilateral processes in coordination with other factors. The proposed review attempts to elaborate an in-depth account of the transcription co-activators, their involvement in transcription regulation, and context-specific contributions to pathophysiological conditions. This review also addresses an issue that has not been dealt with in a comprehensive manner and hopes to direct attention towards future research that will encompass patient-friendly therapeutic strategies, where drugs targeting co-activators will have enhanced benefits and reduced side effects. Additional insights into currently available therapeutic interventions and the associated constraints will eventually reveal multitudes of advanced therapeutic targets aiming for disease amelioration and good patient prognosis.

Rat prostate tumors induce DNA synthesis in remote organs

Advanced cancers induce systemic responses. However, if such systemic changes occur already when aggressive tumors are small, have not been thoroughly characterized. Here, we examined how localized prostate cancers of different sizes and metastatic potential affected DNA synthesis in the rest of the prostate and in various remote organs. Non-metastatic Dunning R-3327 G (G) tumor cells, metastatic MatLyLu (MLL) tumor cells, or vehicle were injected into the prostate of immunocompetent rats. All animals received daily injections of Bromodeoxyuridine (BrdU), to label cells/daughter cells with active DNA synthesis. Equal sized G- and MLL-tumors, similarly increased BrdU-labeling in the prostate, lymph nodes and liver compared to tumor-free controls. Prior to metastasis, MLL-tumors also increased BrdU-labeling in bone marrow and lungs compared to animals with G-tumors or controls. In animals with MLL-tumors, BrdU-labeling in prostate, lungs, brown adipose tissue and skeletal muscles increased in a tumor-size-dependent way. Furthermore, MLL-tumors induced increased signs of DNA damage (γH2AX staining) and accumulation of CD68 + macrophages in the lungs. In conclusion, small localized prostate cancers increased DNA synthesis in several remote tissues in a tumor type- and size-dependent way. This may suggest the possibility for early diagnosis of aggressive prostate cancer by examining tumor-induced effects in other tissues.

Liposomal formulation of HIF-1α inhibitor echinomycin eliminates established metastases of triple-negative breast cancer

Hypoxia-inducible factor 1α (HIF-1α) is recognized as a prime molecular target for metastatic cancer. However, no specific HIF-1α inhibitor has been approved for clinical use. Here, we demonstrated that in vivo efficacy of echinomycin in solid tumors with HIF-1α overexpression is formulation-dependent. Compared to previously-used Cremophor-formulated echinomycin, which was toxic and ineffective in clinical trials, liposomal-echinomycin provides significantly more inhibition of primary tumor growth and only liposome-formulated echinomycin can eliminate established triple-negative breast cancer (TNBC) metastases, which are the leading cause of death from breast cancer, as available therapies remain minimally effective at this stage. Pharmacodynamic analyses reveal liposomal-echinomycin more potently inhibits HIF-1α transcriptional activity in primary and metastasized TNBC cells in vivo, the latter of which are HIF-1α enriched. The data suggest that nanoliposomal-echinomycin can provide safe and effective therapeutic HIF-1α inhibition and could represent the most potent HIF-1α inhibitor in prospective trials for metastatic cancer.

SFMBT2-Mediated Infiltration of Preadipocytes and TAMs in Prostate Cancer

Infiltration of diverse cell types into tumor microenvironment plays a critical role in cancer progression including metastasis. We previously reported that SFMBT2 (Scm-like with four mbt domains 2) regulates the expression of matrix metalloproteinases (MMPs) and migration and invasion of cancer cells in prostate cancer. Here we investigated whether the down-regulation of SFMBT2 regulates the infiltration of preadipocytes and tumor-associated macrophages (TAMs) in prostate cancer. We found that the down-regulation of SFMBT2 promotes the infiltration of preadipocytes and TAMs through up-regulation of CXCL8, CCL2, CXCL10, and CCL20 expression in prostate cancer. Expression of CXCL8, CCL2, CXCL10, and CCL20 was also elevated in prostate cancer patients having a higher Gleason score (≥8), which had substantially lower SFMBT2 expression. We also found that the up-regulation of CXCL8, CCL2, CXCL10, and CCL20 expression is dependent on NF-κB activation in prostate cancer cells expressing a low level of SFMBT2. Moreover, increased IL-6 from infiltrated preadipocytes and TAMs promoted migration and invasion of prostate cancer cells expressing a low level of SFMBT2. Our study may suggest that SFMBT2 a critical regulator for the infiltration of preadipocytes and TAMs into the prostate tumor microenvironment. Thus, the regulation of SFMBT2 may provide a new therapeutic strategy to inhibit prostate cancer metastasis, and SFMBT2 could be used as a potential biomarker in prostate cancer metastasis.

Role of CITED2 in stem cells and cancer

Cbp/P300 interacting transactivator with Glu/Asp-rich carboxy-terminal domain 2 (CITED2) is a transcription co-factor that interacts with several other transcription factors and co-factors, and serves critical roles in fundamental cell processes, including proliferation, apoptosis, differentiation, migration and autophagy. The interacting transcription factors or co-factors of CITED2 include LIM homeobox 2, transcription factor AP-2, SMAD2/3, peroxisome proliferator-activated receptor γ, oestrogen receptor, MYC, Nucleolin and p300/CBP, which regulate downstream gene expression, and serve important roles in the aforementioned fundamental cell processes. Emerging evidence has demonstrated that CITED2 serves an essential role in embryonic and adult tissue stem cells, including hematopoietic stem cells and tendon-derived stem/progenitor cells. Additionally, CITED2 has been reported to function in different types of cancer. Although the functions of CITED2 in different tissues vary depending on the interaction partner, altered CITED2 expression or altered interactions with transcription factors or co-factors result in alterations of fundamental cell processes, and may affect stem cell maintenance or cancer cell survival. The aim of this review is to summarize the molecular mechanisms of CITED2 function and how it serves a role in stem cells and different types of cancer based on the currently available literature.

CITED2 and the modulation of the hypoxic response in cancer

CITED2 (CBP/p300-interacting transactivator with Glu/Asp-rich C-terminal domain, 2) is a ubiquitously expressed protein exhibiting a high affinity for the CH1 domain of the transcriptional co-activators CBP/p300, for which it competes with hypoxia-inducible factors (HIFs). CITED2 is particularly efficient in the inhibition of HIF-1α-dependent transcription in different contexts, ranging from organ development and metabolic homeostasis to tissue regeneration and immunity, being also potentially involved in various other physiological processes. In addition, CITED2 plays an important role in inhibiting HIF in some diseases, including kidney and heart diseases and type 2-diabetes. In the particular case of cancer, CITED2 either functions by promoting or suppressing cancer development depending on the context and type of tumors. For instance, CITED2 overexpression promotes breast and prostate cancers, as well as acute myeloid leukemia, while its expression is downregulated to sustain colorectal cancer and hepatocellular carcinoma. In addition, the role of CITED2 in the maintenance of cancer stem cells reveals its potential as a target in non-small cell lung carcinoma and acute myeloid leukemia, for example. But besides the wide body of evidence linking both CITED2 and HIF signaling to carcinogenesis, little data is available regarding CITED2 role as a negative regulator of HIF-1α specifically in cancer. Therefore, comprehensive studies exploring further the interactions of these two important mediators in cancer-specific models are sorely needed and this can potentially lead to the development of novel targeted therapies.

Targeting Macrophage-Recruiting Chemokines as a Novel Therapeutic Strategy to Prevent the Progression of Solid Tumors

Solid tumors are initiated by genetic mutations in non-hematopoietic cells and progress into invasive malignant tumors. This tumor progression often culminates in metastatic disease that is largely refractory to current therapeutic modalities and thus dramatically reduces survival of tumor patients. As solid tumors account for more than 80% of cancer-related deaths, it is necessary to develop novel therapeutic strategies to treat the diseases. An attractive strategy is to target macrophages in both primary tumors [known as tumor-associated macrophages (TAMs)] and metastatic tumors [called metastasis-associated macrophages (MAMs)]. TAMs and MAMs are abundant in most solid tumors and can promote tumor metastasis. Several studies in various models of solid tumors suggest that the accumulation of TAMs, MAMs, and their progenitor cells is regulated by chemokine ligands released by tumor and stromal cells. Consequently, these macrophage-recruiting chemokines could be potential therapeutic targets to prevent malignant tumor development through disruption of the accumulation of pro-metastatic macrophages. This review will discuss the role of chemokine ligands and their receptors in TAM and MAM accumulation in primary and secondary tumor sites, and finally discuss the therapeutic potential of inhibitors against these macrophage-recruiting chemokines.

CCL20 is overexpressed in hepatocellular carcinoma with bile duct tumor thrombus and correlates negatively with surgical outcome

There is not yet a consensus regarding prognosis of hepatocellular carcinoma (HCC) with bile duct tumor thrombus (BDTT) versus without bile duct tumor thrombus. Chemokine (C-C motif) ligand 20 (CCL20) plays critical roles in the progress of many types of tumor. But the clinicopathological and prognostic value of this marker in HCC with BDTT is unceratin. In this study, we reported that the overall survival (OS) and disease-free survival (DFS) in HCC with BDTT were significantly shorter than in those without BDTT (P<0.05). CCL20 was expressed at a significantly higher level in bile duct tumor thrombus by real-time PCR, western blot, and immunohistochemistry. Patients with high CCL20 expression levels had a poor prognosis. Multivariate survival analysis indicated that CCL20 was an independent prognostic factor for OS. The presence of bile duct tumor thrombus indicateda poor prognosis in HCC patients, but was not a surgical contraindication. CCL20 was associated with tumor progression and high CCL20 expression was correlated with worse surgical outcomes in HCC with BDTT. Inhibition of CCL20 expression might offer novel promising molecular targets for treatment.