TAp73 represses NF-κB-mediated recruitment of tumor-associated macrophages in breast cancer.

Infiltration of tumor-promoting immune cells is a strong driver of tumor progression. Especially the accumulation of macrophages in the tumor microenvironment is known to facilitate tumor growth and to correlate with poor prognosis in many tumor types. TAp73, a member of the p53/p63/p73 family, acts as a tumor suppressor and has been shown to suppress tumor angiogenesis. However, what role TAp73 has in regulating immune cell infiltration is unknown. Here, we report that low levels of TAp73 correlate with an increased NF-κB-regulated inflammatory signature in breast cancer. Furthermore, we show that loss of TAp73 results in NF-κB hyperactivation and secretion of Ccl2, a known NF-κB target and chemoattractant for monocytes and macrophages. Importantly, TAp73-deficient tumors display an increased accumulation of protumoral macrophages that express the mannose receptor (CD206) and scavenger receptor A (CD204) compared to controls. The relevance of TAp73 expression in human breast carcinoma was further accentuated by revealing that TAp73 expression correlates negatively with the accumulation of protumoral CD163+ macrophages in breast cancer patient samples. Taken together, our findings suggest that TAp73 regulates macrophage accumulation and phenotype in breast cancer through inhibition of the NF-κB pathway.

LncRNA TP73-AS1/miR-539/MMP-8 axis modulates M2 macrophage polarization in hepatocellular carcinoma via TGF-ß1 signaling.

PURPOSE: Our study aimed to study the role of lncRNA TP73-AS1/miR-539/MMP-8 axis in modulating M2 macrophage polarization in hepatocellular carcinoma (HCC). METHODS: The gene expression levels of TP73-AS1, miR-539 and MMP-8 were modified by transfection with the overexpression or knockdown vectors. The patient survival rate was analyzed using Kaplan-Meier method. The levels of TP73-AS1, miR-539, MMP-8 and M1/2 macrophage polarization markers were analyzed by qRT-PCR, western blot, and flow cytometry. The release of TGF-ß1 in the supernatant was determined by ELISA assay. The interaction between TP73-AS1, miR-539 and MMP-8 was analyzed by bioinformatics analysis and dual-luciferase reporter assays. Mouse xenograft model was further established to examine the therapeutic effects of the TP73-AS1 knockdown and miR-539 overexpression in vivo. RESULTS: We found TP73-AS1 and MMP-8 upregulation, and miR-539 downregulation in HCC tissues and cell lines. Lower TP73-AS1 and MMP-8 expressions and higher miR-539 expression were associated with higher survival rate of patients. M2-macrophage markers CD206, Arg-1 and CD163 were significantly upregulated in the tumor tissues. TP73-AS1 negatively and directly regulated miR-539 and knockdown of TP73-AS1 inhibited MMP-8 expression and M2 macrophage polarization. Also, overexpression of miR-539 suppressed M2 macrophage polarization by negatively regulating MMP-8. Furthermore, knockdown of MMP-8 also restrained M2 macrophage polarization via inhibiting TGF-ß1 signaling. We also found knockdown of TP73-AS1 or overexpression of miR-539 inhibited HCC tumor growth and M2 macrophage infiltration in vivo. CONCLUSION: Our study demonstrated lncRNA TP73-AS1 negatively regulated miR-539 to promote MMP-8 expression, which activated TGF-ß1 signaling to induce M2 macrophage polarization in HCC.

The specific seroreactivity to ∆Np73 isoforms shows higher diagnostic ability in colorectal cancer patients than the canonical p73 protein.

The p53-family is tightly regulated at transcriptional level. Due to alternative splicing, up to 40 different theoretical proteoforms have been described for p73 and at least 20 and 10 for p53 and p63, respectively. However, only the canonical proteins have been evaluated as autoantibody targets in cancer patients for diagnosis. In this study, we have cloned and expressed in vitro the most upregulated proteoforms of p73, ΔNp73α and ΔNp73ß, for the analysis of their seroreactivity by a developed luminescence based immunoassay test using 145 individual plasma from colorectal cancer, premalignant individuals and healthy controls. ∆Np73α seroreactivity showed the highest diagnostic ability to discriminate between groups. The combination of ∆Np73α, ∆Np73ß and p73 proteoforms seroreactivity were able to improve their individual diagnostic ability. Competitive inhibition experiments further demonstrated the presence of unique specific epitopes in ΔNp73 isoforms not present in p73, with several colorectal patients showing unique and specific seroreactivity to the ΔNp73 proteoforms. Overall, we have increased the complexity of the humoral immune response to the p53-family in cancer patients, showing that the proteoforms derived from the alternative splicing of p73 possess a higher diagnostic ability than the canonical protein, which might be extensive for p53 and p63 proteins.

Persistent IKKα phosphorylation induced apoptosis in UVB and Poly I:C co-treated HaCaT cells plausibly through pro-apoptotic p73 and abrogation of IκBα.

Toll-like receptor 3 (TLR3), a member of pattern recognition receptors, is reported to initiate skin inflammation by recognizing double-strand RNA (dsRNA) released from UVB-irradiated cells. Recently, we have discovered the NF-κB pathway activated by TLR3 is involved in apoptosis of UVB-Poly I:C-treated HaCaT cells. The real culprit for apoptosis has not been precisely identified since the system of NF-κB pathway is complex. In this study, we silenced main transcriptional factors in NF-κB family, RelA, RelB and c-Rel, but to our surprise the results show that none of them participate in apoptosis induction in UVB-Poly I:C-treated HaCaT cells. Therefore, we moved to investigate the apoptosis-associated molecules in the upstream of NF-κB pathway. We firstly checked the expression of IκBα, an NF-κB inhibitor. UVB (4.8 mJ/cm2) and Poly I:C (0.3 µg/mL) co-treatment decreased IκBα expression level in a time-dependent manner. Silencing IκBα with siRNA further enhanced UVB-Poly I:C-induced cell death. We then investigated IκB kinase (IKK) complex that contributes to the degradation of IκBα. IKK is composed of IKKα, IKKß and NEMO. Treatment with IKK-16, an IKKα/ß inhibitor, significantly diminished UVB-Poly I:C-induced IκBα degradation and thus apoptosis. Silencing either IKKα or NEMO but not IKKß with corresponding siRNA inhibited apoptosis. Tumor repressor p73, a homologue of p53, is reported to mediate IKKα-induced apoptosis in DNA damage response. Silencing p73 reduced cell apoptosis in UVB-Poly I:C-treated HaCaT cells. In summary, UVB and Poly I:C co-treatment activates IKKα and NEMO, which diminishes anti-apoptotic IκBα, resulting in enhancement of apoptosis through p73. The findings partially clarify the possible molecular mechanism of pro-apoptotic NF-κB pathway activated by TLR3 in the fate of UVB-irradiated epidermis.

Keratinocytes in atopic dermatitis express abundant ΔNp73 regulating thymic stromal lymphopoietin production via NF-κB.

BACKGROUND: Atopic dermatitis (AD) is a chronic inflammatory skin disease that often cannot be completely controlled by modern medicine. Since multiple factors are intricately involved in the pathogenesis of AD, wide-ranging research is required for further advancement of AD treatment. Epidermal keratinocytes are the forefront to the external environment and play a pivotal role in the initiation of immune reaction against exogenous invasion. OBJECTIVE: Thymic stromal lymphopoietin (TSLP) is a keratinocyte-derived cytokine that induces differentiation and activation of type 2 helper T cells and innate lymphoid cells, cardinal effectors in pathophysiology of AD. We previously reported that ΔNp63, a p53-related molecule, regulates the expression of TSLP receptors and suggested the entity of a potential TSLP autocrine loop in the AD epidermis. In this study, we further explored the significance of p53 family transcription factors in TSLP production from human keratinocytes. METHOD: Expression profile of p73, a p53-related molecule, was evaluated in human AD tissue by immunohistochemistry. In addition, the function of p73 in producing TSLP was investigated with in vitro cultured keratinocytes via molecular biological analysis. RESULTS: ΔNp73 was abundantly expressed in the AD epidermis and increased the release of TSLP via NF-κB activation. Furthermore, the Toll-like receptor 3 signal enhanced ΔNp73 expression and thereby induced TSLP expression. CONCLUSION: Our results indicate that ΔNp73 is an additional participant in the mechanism of TSLP production. Amending the aberrant state of keratinocytes, represented by overexpression of ΔNp73, can be a novel therapeutic target of AD.