SHON Is a Novel Estrogen-Regulated Oncogene in Mammary Carcinoma That Predicts Patient Response to Endocrine Therapy

Non-Invasive Biomarkers for Early Detection of Breast Cancer

Breast cancer is the most common cancer in women worldwide. Accurate early diagnosis of breast cancer is critical in the management of the disease. Although mammogram screening has been widely used for breast cancer screening, high false-positive and false-negative rates and radiation from mammography have always been a concern. Over the last 20 years, the emergence of "omics" strategies has resulted in significant advances in the search for non-invasive biomarkers for breast cancer diagnosis at an early stage. Circulating carcinoma antigens, circulating tumor cells, circulating cell-free tumor nucleic acids (DNA or RNA), circulating microRNAs, and circulating extracellular vesicles in the peripheral blood, nipple aspirate fluid, sweat, urine, and tears, as well as volatile organic compounds in the breath, have emerged as potential non-invasive diagnostic biomarkers to supplement current clinical approaches to earlier detection of breast cancer. In this review, we summarize the current progress of research in these areas.

SHON expression predicts response and relapse risk of breast cancer patients after anthracycline-based combination chemotherapy or tamoxifen treatment

Background

SHON nuclear expression (SHON-Nuc⁺) was previously reported to predict clinical outcomes to tamoxifen therapy in ERα⁺ breast cancer (BC). Herein we determined if SHON expression detected by specific monoclonal antibodies could provide a more accurate prediction and serve as a biomarker for anthracycline-based combination chemotherapy (ACT).

Methods

SHON expression was determined by immunohistochemistry in the Nottingham early-stage-BC cohort (n = 1,650) who, if eligible, received adjuvant tamoxifen; the Nottingham ERα⁻ early-stage-BC (n = 697) patients who received adjuvant ACT; and the Nottingham locally advanced-BC cohort who received pre-operative ACT with/without taxanes (Neo-ACT, n = 120) and if eligible, 5-year adjuvant tamoxifen treatment. Prognostic significance of SHON and its relationship with the clinical outcome of treatments were analysed.

Results

As previously reported, SHON-Nuc⁺ in high risk/ERα⁺ patients was significantly associated with a 48% death risk reduction after exclusive adjuvant tamoxifen treatment compared with SHON-Nuc⁻ [HR (95% CI) = 0.52 (0.34–0.78), p = 0.002]. Meanwhile, in ERα⁻ patients treated with adjuvant ACT, SHON cytoplasmic expression (SHON-Cyto⁺) was significantly associated with a 50% death risk reduction compared with SHON-Cyto⁻ [HR (95% CI) = 0.50 (0.34–0.73), p = 0.0003]. Moreover, in patients received Neo-ACT, SHON-Nuc⁻ or SHON-Cyto⁺ was associated with an increased pathological complete response (pCR) compared with SHON-Nuc⁺ [21 vs 4%; OR (95% CI) = 5.88 (1.28–27.03), p = 0.012], or SHON-Cyto⁻ [20.5 vs. 4.5%; OR (95% CI) = 5.43 (1.18–25.03), p = 0.017], respectively. After receiving Neo-ACT, patients with SHON-Nuc⁺ had a significantly lower distant relapse risk compared to those with SHON-Nuc⁻ [HR (95% CI) = 0.41 (0.19–0.87), p = 0.038], whereas SHON-Cyto⁺ patients had a significantly higher distant relapse risk compared to SHON-Cyto⁻ patients [HR (95% CI) = 4.63 (1.05–20.39), p = 0.043]. Furthermore, multivariate Cox regression analyses revealed that SHON-Cyto⁺ was independently associated with a higher risk of distant relapse after Neo-ACT and 5-year tamoxifen treatment [HR (95% CI) = 5.08 (1.13–44.52), p = 0.037]. The interaction term between ERα status and SHON-Nuc⁺ (p = 0.005), and between SHON-Nuc⁺ and tamoxifen therapy (p = 0.007), were both statistically significant.

Conclusion

SHON-Nuce⁺ in tumours predicts response to tamoxifen in ERα⁺ BC while SHON-Cyto⁺ predicts response to ACT.

Interferon-γ Promotes Inflammation and Development of T-Cell Lymphoma in HTLV-1 bZIP Factor Transgenic Mice

Human T-cell leukemia virus type 1 (HTLV-1) is an etiological agent of several inflammatory diseases and a T-cell malignancy, adult T-cell leukemia (ATL). HTLV-1 bZIP factor (HBZ) is the only viral gene that is constitutively expressed in HTLV-1-infected cells, and it has multiple functions on T-cell signaling pathways. HBZ has important roles in HTLV-1-mediated pathogenesis, since HBZ transgenic (HBZ-Tg) mice develop systemic inflammation and T-cell lymphomas, which are similar phenotypes to HTLV-1-associated diseases. We showed previously that in HBZ-Tg mice, HBZ causes unstable Foxp3 expression, leading to an increase in regulatory T cells (Tregs) and the consequent induction of IFN-γ-producing cells, which in turn leads to the development of inflammation in the mice. In this study, we show that the severity of inflammation is correlated with the development of lymphomas in HBZ-Tg mice, suggesting that HBZ-mediated inflammation is closely linked to oncogenesis in CD4+ T cells. In addition, we found that IFN-γ-producing cells enhance HBZ-mediated inflammation, since knocking out IFN-γ significantly reduced the incidence of dermatitis as well as lymphoma. Recent studies show the critical roles of the intestinal microbiota in the development of Tregs in vivo. We found that even germ-free HBZ-Tg mice still had an increased number of Tregs and IFN-γ-producing cells, and developed dermatitis, indicating that an intrinsic activity of HBZ evokes aberrant T-cell differentiation and consequently causes inflammation. These results show that immunomodulation by HBZ is implicated in both inflammation and oncogenesis, and suggest a causal connection between HTLV-1-associated inflammation and ATL.

SHON, a novel secreted protein, regulates epithelial-mesenchymal transition through transforming growth factor-β signaling in human breast cancer cells

The epithelial-mesenchymal transition (EMT) is one of the main mechanisms contributing to the onset of cancer metastasis, and has proven to be associated with breast cancer progression. SHON is a novel secreted hominoid-specific protein we have previously identified; it is specifically expressed in all human cancer cell lines tested and is oncogenic for human mammary carcinoma cells. Here, we show that ectopic overexpression of SHON in immortalized human mammary epithelial cells is sufficient for cells to acquire the mesenchymal traits, as well as the enhanced cell migration and invasion, along with the epithelial stem cell properties characterized by increased CD44(high) /CD24(low) subpopulation and mammosphere-forming ability. Moreover, we demonstrate that SHON positively activates the autocrine transforming growth factor-β (TGF-β) pathway to contribute to EMT, while SHON itself is induced by TGF-β in mammary epithelial cells. These data are in favor of a SHON-TGFβ-SHON-positive feedback loop that regulates EMT program in breast cancer progression. Finally, examination of the human clinic breast cancer specimens reveals that tumor cells may extracellularly release SHON protein to promote the cancerization of surrounding cells. Together, our findings define an important function of SHON in regulation of EMT via TGF-β signaling, which is closely associated with the invasive subtypes of human breast cancer.