HOX transcription factors play an important role in determining body patterning and cell fate during embryogenesis. Accumulating evidence has shown that these genes act as positive and/or negative modulators in many types of cancer, including breast cancer, in a tissue-specific manner. We have previously reported that HOXB5 is aberrantly overexpressed in breast cancer tissues and cell lines. Here, we investigated the biological roles and clinical relevance of HOXB5 in breast cancer. Immunohistochemical analysis of HOXB5 on tissue microarray (TMA) including 34 normal and 67 breast cancer specimens revealed that HOXB5 was highly expressed in cancer tissues, particularly from estrogen receptor (ER)-positive breast cancer patients. An online survival analysis confirmed the correlation between HOXB5 expression and poor distant metastasis-free survival in ER-positive, but not in ER-negative, breast cancer. In vitro studies indicated that HOXB5 silencing in ER-positive cells significantly decreased cell proliferation and anchorage-independent cell growth. In contrast, overexpression of HOXB5 displayed EMT characteristics with a greater invasive ability, higher cell proliferation and colony formation in soft agar. HOXB5 knockdown or overexpression led to changes in the expression levels of RET, ERBB2, and EGFR, but not of ESR1. In conclusion, we suggest that HOXB5 acts as a positive modulator most likely by promoting cell proliferative response and invasiveness in ER-positive breast cancer. These results would help predict prognosis of breast cancer and identify a new valuable therapeutic target.
HOX genes encode a family of transcriptional regulators that are involved in pattern formation and organogenesis during embryo development. In addition, these genes play important roles in adult tissues and some of the dysregulated HOX genes are associated with cancer development and metastasis. Like many other HOX genes, HOXC9 is aberrantly expressed in certain breast cancer cell lines and tissues; however, its specific functions in breast cancer progression were not investigated. In the present study, we demonstrated that HOXC9 overexpression in breast cancer cell lines such as MDA-MB-231 and MCF7 increased the invasiveness but reduced the proliferation of cells, resembling a phenotype switch from a proliferative to an invasive state. Furthermore, the reciprocal result was detected in MCF7 and BT474 cells when the expression level of HOXC9 was reduced with siRNA. The clinical impact of HOXC9 in breast cancer was interpreted from the survival analysis data, in which high HOXC9 expression led to considerably poorer disease-free survival and distant metastasis-free survival, especially in lymph node-positive patients. Together, the prognostic relevance of HOXC9 and the HOXC9-derived phenotypic switch between proliferative and invasive states in the breast cancer cell lines suggest that HOXC9 could be a prognostic marker in breast cancer patients with lymph node metastasis and a target for therapeutic intervention in malignant breast cancer.
Tamoxifen (TAM) is commonly used to treat estrogen receptor (ER)-positive breast cancer. Despite the remarkable benefits, resistance to TAM presents a serious therapeutic challenge. Since several HOX transcription factors have been proposed as strong candidates in the development of resistance to TAM therapy in breast cancer, we generated an in vitro model of acquired TAM resistance using ER-positive MCF7 breast cancer cells (MCF7-TAMR), and analyzed the expression pattern and epigenetic states of HOX genes. HOXB cluster genes were uniquely up-regulated in MCF7-TAMR cells. Survival analysis of in slico data showed the correlation of high expression of HOXB genes with poor response to TAM in ER-positive breast cancer patients treated with TAM. Gain- and loss-of-function experiments showed that the overexpression of multi HOXB genes in MCF7 renders cancer cells more resistant to TAM, whereas the knockdown restores TAM sensitivity. Furthermore, activation of HOXB genes in MCF7-TAMR was associated with histone modifications, particularly the gain of H3K9ac. These findings imply that the activation of HOXB genes mediate the development of TAM resistance, and represent a target for development of new strategies to prevent or reverse TAM resistance.
Benzo[a]pyrene (B[a]P), a polycyclic aromatic hydrocarbon formed during the incomplete combustion of organic matter, has harmful effects. Therefore, much research is ongoing to develop agents that can mitigate the effects of B[a]P. The aim of this study was to examine the effect of maclurin, one component of the branches of Morus alba L., on the B[a]P-induced effects in HaCaT cells, a human keratinocyte cell line. Maclurin treatment inhibited aryl hydrocarbon receptor (AHR) signaling as evidenced by reduced xenobiotic response element (XRE) reporter activity, decreased expression of cytochrome P450 1A1 (CYP1A1), and reduced nuclear translocation of AHR. The B[a]P-induced dissociation of AHR from AHR-interacting protein (AIP) was suppressed by maclurin. Maclurin also inhibited the production of intracellular reactive oxygen species (ROS) induced by B[a]P. In addition, the antioxidant property of maclurin itself was demonstrated by the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay. Furthermore, maclurin activated antioxidant response element (ARE) signaling through enhancement of ARE luciferase reporter activity and the expression of ARE-dependent genes including nuclear factor (erythroid-derived 2)-like 2 (Nrf2) and heme oxygenase-1 (HO-1). Nrf2 activation and its nuclear translocation were promoted by maclurin through p38 MAPK activation. These data indicate that maclurin had antagonistic activity against B[a]P effects through activation of Nrf2-mediated signaling and inhibition of AHR signaling and, suggesting its potential in protecting from harmful B[a]P-containing pollutants.
Identifying materials contributing to skin hydration, essential for normal skin homeostasis, has recently gained increased research interest. In this study, we investigated the potential benefits and mechanisms of action of Aspergillus oryzae-fermented wheat peptone (AFWP) on the proliferation and hydration of human skin keratinocytes, through in vitro experiments using HaCaT cell lines. The findings revealed that compared to unfermented wheat peptone, AFWP exhibited an improved amino acid composition, significantly (p < 0.05) higher DPPH scavenging capability and cell proliferation activity, and reduced lipopolysaccharide-induced NO production in RAW 264.7 cells. Furthermore, we separated AFWP into eleven fractions, each ≤2 kDa; of these, fraction 4 (AFW4) demonstrated the highest efficacy in the cell proliferation assay and was found to be the key component responsible for the cell proliferation potential and antioxidant properties of AFWP. Additionally, AFW4 increased the expression of genes encoding natural moisturizing factors, including filaggrin, transglutaminase-1, and hyaluronic acid synthase 1–3. Furthermore, AFW4 activated p44/42 MAPK, but not JNK and p38 MAPK, whereas PD98059, a p44/42 MAPK inhibitor, attenuated the beneficial effects of AFW4 on the skin, suggesting that the effects of AFW4 are mediated via p44/42 MAPK activation. Finally, in clinical studies, AFW4 treatment resulted in increased skin hydration and reduced trans-epidermal water loss compared with a placebo group. Collectively, these data provide evidence that AFW4 could be used as a potential therapeutic agent to improve skin barrier damage induced by external stresses.
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