Increased SOX2 expression in less differentiated breast carcinomas and their lymph node metastases

The multifaceted role of SOX2 in breast and lung cancer dynamics

Breast and lung cancers are leading causes of death among patients, with their global mortality and morbidity rates increasing. Conventional treatments often prove inadequate due to resistance development. The alteration of molecular interactions may accelerate cancer progression and treatment resistance. SOX2, known for its abnormal expression in various human cancers, can either accelerate or impede cancer progression. This review focuses on examining the role of SOX2 in breast and lung cancer development. An imbalance in SOX2 expression can promote the growth and dissemination of these cancers. SOX2 can also block programmed cell death, affecting autophagy and other cell death mechanisms. It plays a significant role in cancer metastasis, mainly by regulating the epithelial-to-mesenchymal transition (EMT). Additionally, an imbalanced SOX2 expression can cause resistance to chemotherapy and radiation therapy in these cancers. Genetic and epigenetic factors may affect SOX2 levels. Pharmacologically targeting SOX2 could improve the effectiveness of breast and lung cancer treatments.

Prognostic role of SOX2 and STAT3 expression on circulating T lymphocytes and CD44+/CD24neg cells in the locally advanced and metastatic breast cancer

BACKGROUND

Breast cancer (BC) is associated with a continuous increase in incidence, with high mortality rates in several countries. CD44, STAT3, and SOX2 are related to regulating of somatic cell division, tumorigenesis, and metastasis in BC.

METHODS

A cross-sectional study was carried out at the Hospital de Cancer de Pernambuco (HCP) between 2017 and 2018. Fifty-one women with locally advanced (LA) and 14 with metastatic BC were included in the study.

RESULTS

High CD44+/CD24neg and CD44+/CD24neg/SOX2+ levels in Luminal B (LB), HER2+, and triple-negative breast cancer (TNBC) compared with controls (p < 0.05). Low CD44+/CD24negSTAT3+ levels in LB, HER2+, and TNBC compared with controls (p < 0.05). High T lymphocytes, and low STAT3 + T, and SOX2 + T levels in BC patients (p < 0.05). High SOX2 + T levels in patients with axillary lymph node-negative (N0) compared with the axillary lymph node-positives (N1 and N2 groups; p < 0.05). High SOX2 + T levels in N1 compared to N2 (p < 0.05). High T lymphocytes and low SOX2 + T levels in the LA tumor compared to metastatic disease (p = 0.0007 and p = 0.02, respectively). High CD44 + /CD24negSTAT3+, and T lymphocyte levels in TNBC patients with LA tumor compared to metastatic (p < 0.05). Low STAT3 + T levels in TBNC patients with LA tumor compared to metastatic (p = 0.0266).

CONCLUSION

SOX2 and STAT3 expression on circulating T lymphocytes and CD44 + /CD24neg cells in peripheral blood have prognostic roles in breast cancer. SOX2 and STAT3 expression are potential predictive biomarkers of disease progression in breast cancer regardless of tumor subtype.

p53 isoform expression promotes a stemness phenotype and inhibits doxorubicin sensitivity in breast cancer

In breast cancer, dysregulated TP53 expression signatures are a better predictor of chemotherapy response and survival outcomes than TP53 mutations. Our previous studies have shown that high levels of Δ40p53 are associated with worse disease-free survival and disruption of p53-induced DNA damage response in breast cancers. Here, we further investigated the in vitro and in vivo implications of Δ40p53 expression in breast cancer. We have shown that genes associated with cell differentiation are downregulated while those associated with stem cell regulation are upregulated in invasive ductal carcinomas expressing high levels of Δ40p53. In contrast to p53, endogenous ∆40p53 co-localised with the stem cell markers Sox2, Oct4, and Nanog in MCF-7 and ZR75-1 cell lines. ∆40p53 and Sox2 co-localisation was also detected in breast cancer specimens. Further, in cells expressing a high ∆40p53:p53 ratio, increased expression of stem cell markers, greater mammosphere and colony formation capacities, and downregulation of miR-145 and miR-200 (p53-target microRNAs that repress stemness) were observed compared to the control subline. In vivo, a high ∆40p53:p53 ratio led to increased tumour growth, Ki67 and Sox2 expression, and blood microvessel areas in the vehicle-treated mice. High expression of ∆40p53 also reduced tumour sensitivity to doxorubicin compared to control tumours. Enhanced therapeutic efficacy of doxorubicin was observed when transiently targeting Δ40p53 or when treating cells with OTSSP167 with concomitant chemotherapy. Taken together, high Δ40p53 levels induce tumour growth and may promote chemoresistance by inducing a stemness phenotype in breast cancer; thus, targeting Δ40p53 in tumours that have a high Δ40p53:p53 ratio could enhance the efficacy of standard-of-care therapies such as doxorubicin.

Understanding the function and regulation of Sox2 for its therapeutic potential in breast cancer

Sox family of transcriptional factors play essential functions in development and are implicated in multiple clinical disorders, including cancer. Sox2 being their most prominent member and performing a critical role in reprogramming differentiated adult cells to an embryonic phenotype is frequently upregulated in multiple cancers. High Sox2 levels are detected in breast tumor tissues and correlate with a worse prognosis. In addition, Sox2 expression is connected with resistance to conventional anticancer therapy. Together, it can be said that inhibiting Sox2 expression can reduce the malignant features associated with breast cancer, including invasion, migration, proliferation, stemness, and chemoresistance. This review highlights the critical roles played by the Sox gene family members in initiating or suppressing breast tumor development, while primarily focusing on Sox2 and its role in breast tumor initiation, maintenance, and progression, elucidates the probable mechanisms that control its activity, and puts forward potential therapeutic strategies to inhibit its expression.

Polyploid giant cancer cells, stemness and epithelial-mesenchymal plasticity elicited by human cytomegalovirus

A growing body of evidence is recognizing human cytomegalovirus (HCMV) as a potential oncogenic virus. We hereby provide the first experimental in vitro evidence for HCMV as a reprogramming vector, through the induction of dedifferentiation of mature human mammary epithelial cells (HMECs), generation of a polyploid giant cancer cell (PGCC) phenotype characterized by sustained growth of blastomere-like cells, in concordance with the acquisition of embryonic stem cells characteristics and epithelial-mesenchymal plasticity. HCMV presence parallels the succession of the observed cellular and molecular events potentially ensuing the transformation process. Correlation between PGCCs detection and HCMV presence in breast cancer tissue further validates our hypothesis in vivo. Our study indicates that some clinical HCMV strains conserve the potential to transform HMECs and fit with a "blastomere-like" model of oncogenesis, which may be relevant in the pathophysiology of breast cancer and other adenocarcinoma, especially of poor prognosis.

Unfavorable Prognostic Effects of the Stem Cell Pluripotency Factor Sox2 in Feline Invasive Mammary Carcinomas

Background: Sex-determining Region Y (SRY)-box transcription factor-2 (Sox2) belongs to the "Yamanaka's factors," necessary and sufficient to convert somatic cells into pluripotent stem cells. In breast cancers, Sox2 expression has been associated with poor prognosis, and resistance to therapy. The aims of this study were to determine the frequency of Sox2 positivity in feline invasive mammary carcinomas (FMCs), its relationships with other clinical-pathologic variables, and with patient outcomes. Materials and Methods: This study relies on a previously described retrospective cohort of 180 FMCs, diagnosed in female cats treated by mastectomy alone, with 2-year follow-up. Sox2 (clone SP76), Estrogen Receptor alpha (ER), Progesterone Receptor (PR), Ki-67, Human Epidermal growth factor Receptor 2 (HER2), Androgen Receptor (AR), Bcl-2, Forkhead box protein A1 (FOXA1), basal markers and FoxP3-positive regulatory T cells (Tregs) were detected by automated immunohistochemistry. Sox2 expression was quantitated as an index (percentage of neoplastic cells demonstrating a positive nuclear signal). The FMCs were considered Sox2-positive at threshold >42%. Results: Sox2 was not expressed in the normal mammary gland or in mammary hyperplasia without atypia, but was occasionally detected in atypical hyperplasia. In FMCs, the mean Sox2 index was 38 ± 30%, and 79/180 FMCs (44%) were Sox2-positive. Sox2 expression was associated with older age at diagnosis, lymphovascular invasion, high Ki-67 proliferation indexes, low PR and FOXA1 expression, and increased numbers of tumor-associated Tregs, but was not significantly associated with the clinical stage, histological types, and histological grade. By multivariate survival analysis, Sox2 was associated with poor cancer-specific survival (Hazard Ratio = 1.48, 95% confidence interval 1.04-2.11, p = 0.0292), independently of the pathologic tumor size, pathologic nodal stage, distant metastasis, and AR expression. A rare subgroup of FMCs characterized by an AR+Sox2-phenotype (19/180 cases, 11%) was associated with very favorable outcomes. Conclusion: Sox2 expression was associated with poor cancer-specific survival of female cats with invasive mammary carcinomas, as previously reported in human breast cancer, but was more commonly expressed in cats than reported in breast cancers. Sox2 showed complementarity with AR in FMC prognostication.

Functional characterization of SOX2 as an anticancer target

SOX2 is a well-characterized pluripotent factor that is essential for stem cell self-renewal, reprogramming, and homeostasis. The cellular levels of SOX2 are precisely regulated by a complicated network at the levels of transcription, post-transcription, and post-translation. In many types of human cancer, SOX2 is dysregulated due to gene amplification and protein overexpression. SOX2 overexpression is associated with poor survival of cancer patients. Mechanistically, SOX2 promotes proliferation, survival, invasion/metastasis, cancer stemness, and drug resistance. SOX2 is, therefore, an attractive anticancer target. However, little progress has been made in the efforts to discover SOX2 inhibitors, largely due to undruggable nature of SOX2 as a transcription factor. In this review, we first briefly introduced SOX2 as a transcription factor, its domain structure, normal physiological functions, and its involvement in human cancers. We next discussed its role in embryonic development and stem cell-renewal. We then mainly focused on three aspects of SOX2: (a) the regulatory mechanisms of SOX2, including how SOX2 level is regulated, and how SOX2 cross-talks with multiple signaling pathways to control growth and survival; (b) the role of SOX2 in tumorigenesis and drug resistance; and (c) current drug discovery efforts on targeting SOX2, and the future perspectives to discover specific SOX2 inhibitors for effective cancer therapy.

The Clinical and Molecular Characteristics of Sex-Determining Region Y-Box 2 and its Prognostic Value in Breast Cancer: A Systematic Meta-Analysis

Objective

Transcription factor SOX2 (sex-determining region Y-box 2) has a crucial role in the maintenance of the stem cell state. However, current evidence regarding the role of SOX2 in breast cancer is conflicting. We conducted this meta-analysis to clarify the association of SOX2 expression with clinical and molecular features and its prognostic effect on breast cancer.

Methods

All relevant articles were searched using electronic databases. The pooled odds ratios (ORs) or hazard ratios (HRs: multivariate Cox survival analysis) with their 95% confidence intervals (CIs) were calculated.

Results

A final total of 18 studies containing 3,080 patients with breast cancer were included. SOX2 protein expression was not related to age, menopausal status, lymph node metastasis, lymphovascular invasion, molecular estrogen receptor status, progesterone receptor status, triple-negative status, and the overall survival in breast cancer, but was closely associated with advanced tumor grade (grade 3 vs. grade 1-2: OR = 2.74, 95% CI = 1.85-4.06, p < 0.001), clinical stage (stage 3-4 vs. stage 0-2: OR = 2.46, 95% CI = 1.37-4.40, p = 0.002), pT stage (T stage 2-4 vs. T stage 1: OR = 1.52, 95% CI = 1.07-2.17, p = 0.019), molecular human epidermal growth factor receptor 2 (HER2) status (positive vs. negative: OR = 1.61, 95% CI = 1.21-2.14, p = 0.001), epidermal growth factor receptor (EGFR) status (positive vs. negative: OR = 2.21, 95% CI = 1.13-4.33, p = 0.021), and worse disease-free survival (DFS) (HR = 2.66, 95% CI = 1.20-5.91, p = 0.016) of breast cancer.

Conclusions

SOX2 expression is correlated with breast cancer progression, HER2 status, and EGFR status, and may be an independent prognostic marker for predicting poor DFS.

Comparative Expression of RAGE and SOX2 in Benign and Malignant Prostatic Lesions

Background: Prostate cancer (PCa) is a common health problem in elderly. RAGE (Receptor for advanced glycation end products) is overexpressed in multiple human cancers. SOX2 (Sex-determining region Y box 2) also functions as an oncoprotein and promotes cancer progression but the mechanisms involved remain largely unknown. Aim: The current study investigated the expression patterns of RAGE and SOX2 in benign and malignant prostate samples in correlation with the histopathological findings in order to evaluate their role as prognostic markers or therapeutic targets. Methods: Immunohistochemical staining for RAGE and SOX2 antibodies was applied on 87 prostatic biopsies [16 of prostatitis, 20 of benign prostatic hyperplasia (BPH) and 51 of PCa]. Results: Expression of RAGE and SOX2 (percentage of positive cells) was significantly higher in PCa lesions compared with prostatitis (p<0.01) and BPH (p<0.0001) and was also significantly higher in prostatitis compared with BPH lesions (p<0.01). Also, percentage of positive RAGE and SOX2 cells showed a significant stepwise increase from Gleason Grade 3 to Grade 5 and were significantly higher in high Gleason Scores (≥8) compared to lower Scores (≤7) with statistical significance (p=0.001). Conclusion: RAGE and SOX2 were up-regulated in prostate cancer lesions, mainly in advanced grades, suggesting an active role of both antigens in the development and progression of prostate cancer and expecting the possibility of their use as therapeutic targets.

Prognostic Value of CD133 and SOX2 in Advanced Cancer

BACKGROUND

The prognostic value of CD133 and SOX2 expression in advanced cancer remains unclear. This study was first conducted to investigate the association between CD133 or SOX2 positivity and clinical outcomes for advanced cancer patients.

METHODS

Hazard ratios (HRs) with 95% confidence intervals (95% CIs) were calculated to evaluate the correlation between CD133 or SOX2 positivity and overall survival (OS), disease-free survival (DFS), progression-free survival (PFS), cancer-specific survival (CSS), or recurrence-free survival (RFS) from multivariable analysis. Trial sequential analysis (TSA) was also performed.

RESULTS

13 studies with 1358 cases (CD133) and five studies with 433 cases (SOX2) were identified. CD133 positivity was correlated with worse CSS and OS, but there was no correlation between CD133 positivity and DFS. SOX2 positivity was associated with poor DFS and RFS but was not linked to PFS. Stratified analysis by study source showed that only CD133 positivity can decrease OS for Chinese patients. Stratified analysis by treatment regimens indicated that CD133 positivity was linked to poor OS in patients treated with adjuvant therapy. TSA showed that additional studies were necessary.

CONCLUSIONS

CD133 and SOX2 might be associated with worse prognosis in advanced cancer. More prospective studies are strongly needed.

IMPACT

CD133 and SOX2 may be promising targeted molecular therapy for advanced cancer patients.

The organic ester O,O'-diethyl-(S,S)-ethylenediamine-N,N'-di-2-(3-cyclohexyl)propanoate dihydrochloride attenuates murine breast cancer growth and metastasis

Pharmacological treatment of cancer is mostly limited by drug-toxicity and resistance. It has been noticed that new organic ester ligand, O,O’-diethyl-(S,S)-ethylenediamine-N,N’-di-2-(3-cyclohexyl)propanoate dihydrochloride (named DE-EDCP) showed effective cytotoxic capacities against several human and mouse cancer cell lines. However, its effects on tumor growth and metastasis are unexplored. The aim of present study was to examine the ability of DE-EDCP to inhibit 4T1 murine breast cancer growth and progression and to explore possible molecular mechanisms. DE-EDCP exhibited significant tumoricidal activity on human and murine breast cancer cell lines. Further, marked reduction of murine breast cancer growth and progression by DE-EDCP was shown. DE-EDCP exhibits fewer side-effects compared to cisplatin as a conventional chemotherapeutic. Results obtained from in vivo and in vitro experiments indicate that DE-EDCP induces apoptosis and inhibits proliferation of 4T1 cells. DE-EDCP increases percentage of 4T1 cells in late apoptosis, expression of pro-apoptotic Bax and caspase-3, while decreases expression of anti-apoptotic Bcl-2. DE-EDCP treatment increased the percentage of TUNEL-positive nuclei and reduced Ki-67 expression in breast cancer tissue. DE-EDCP decreased expression of cyclin D3 and Ki-67, increased expression of cyclin-dependent kinase inhibitors p16, p21 and p27 and arrested 4T1 cells in G0/G1 cell cycle phase. Expression of STAT3 and downstream regulated molecules, NANOG and SOX2, was reduced in 4T1 cells after DE-EDCP treatment.

In conclusion, DE-EDCP impairs breast cancer growth and progression by triggering cancer cell death and inhibition of cancer cell proliferation. DE-EDCP might be of interest in the development of the new anticancer agent.

Limited utility of tissue micro-arrays in detecting intra-tumoral heterogeneity in stem cell characteristics and tumor progression markers in breast cancer

Background

Intra-tumoral heterogeneity has been recently addressed in different types of cancer, including breast cancer. A concept describing the origin of intra-tumoral heterogeneity is the cancer stem-cell hypothesis, proposing the existence of cancer stem cells that can self-renew limitlessly and therefore lead to tumor progression. Clonal evolution in accumulated single cell genomic alterations is a further possible explanation in carcinogenesis. In this study, we addressed the question whether intra-tumoral heterogeneity can be reliably detected in tissue-micro-arrays in breast cancer by comparing expression levels of conventional predictive/prognostic tumor markers, tumor progression markers and stem cell markers between central and peripheral tumor areas.

Methods

We analyzed immunohistochemical expression and/or gene amplification status of conventional prognostic tumor markers (ER, PR, HER2, CK5/6), tumor progression markers (PTEN, PIK3CA, p53, Ki-67) and stem cell markers (mTOR, SOX2, SOX9, SOX10, SLUG, CD44, CD24, TWIST) in 372 tissue-micro-array samples from 72 breast cancer patients. Expression levels were compared between central and peripheral tumor tissue areas and were correlated to histopathological grading. 15 selected cases additionally underwent RNA sequencing for transcriptome analysis.

Results

No significant difference in any of the analyzed between central and peripheral tumor areas was seen with any of the analyzed methods/or results that showed difference. Except mTOR, PIK3CA and SOX9 (nuclear) protein expression, all markers correlated significantly (p < 0.05) with histopathological grading both in central and peripheral areas.

Conclusion

Our results suggest that intra-tumoral heterogeneity of stem-cell and tumor-progression markers cannot be reliably addressed in tissue-micro-array samples in breast cancer. However, most markers correlated strongly with histopathological grading confirming prognostic information as expression profiles were independent on the site of the biopsy was taken.

Electronic supplementary material

The online version of this article (10.1186/s12967-018-1495-6) contains supplementary material, which is available to authorized users.

Expression of sex-determining region Y-box protein 2 in breast cancer and its clinical significance

Sex-determining region Y-box protein 2 (SOX2) is an embryo transcription factor located on chromosome 3q26.3-q27. It plays an important role in the maintenance of differentiation and self-renewal of pluripotent stem cells. Studies have shown that SOX2 is associated with multiple cancers and is overexpressed in many different phenotypes of breast cancer. To study the relationship between SOX2 and clinicopathological parameters of breast cancer patients, we found that the expression of SOX2 was closely related to the increase in tumor size, histological grade, lymph node metastasis, and high invasiveness. Therefore, studies on the role of SOX2 in breast cancer may provide effective biomarkers and potential therapeutic targets for the diagnosis and treatment of breast cancer. This article will discuss the role of SOX2 in breast cancer, including its occurrence, invasion and metastasis, diagnosis and treatment, relapse, resistance, and prognosis.

Low SOX2 expression marks a distinct subset of adenoid cystic carcinoma of the head and neck and is associated with an advanced tumor stage

Introduction

The transcription factor SOX2 has been identified as a lineage survival oncogene in squamous cell carcinoma and copy number gain is a common event in several human malignancies including head and neck cancer. However, the regulation and function of SOX2 during carcinogenesis as well as its prognostic value appears to be highly context dependent. As an example, high SOX2 expression in lung squamous cell carcinoma (SCC) is related to a favorable prognosis, while it is associated with poor outcome in lung adenocarcinoma. More recently, higher SOX2 levels and improved survival was also reported for head and neck SCC (HNSCC), and silencing of SOX2 expression in HNSCC cell lines revealed a mesenchymal-like phenotype with prominent vimentin expression. So far, SOX2 expression and its clinical relevance for other head and neck cancers, such as adenoid cystic carcinoma (HNACC) have not been sufficiently investigated.

Material and methods

SOX2, vimentin and E-cadherin expression was assessed by immunohistochemical staining on serial sections from formalin fixed and paraffin embedded tissue samples of a patient cohort (n = 45) with primary ACC and correlated with patient and tumor characteristics as well as survival.

Results

High SOX2 expression was found in 14 (31%) primary tumor specimens and was significantly correlated with a N0 lymph node status (p = 0.04), while low SOX2 expression was correlated with a solid growth pattern (p = 0.031). Of the 45 patients, 27 tumor samples resembled an EMT-like phenotype, as assessed by high vimentin and low E-cadherin levels. However, in HNACC SOX2 levels were neither correlated with vimentin nor with E-cadherin expression, further supporting a context dependent regulation and function of SOX2 in distinct tumor entities.

Conclusion

The absence of SOX2 was predominantly found in solid HNACC, which are characterized by a more aggressive phenotype in ACC. However, the underlying molecular mechanisms of SOX2 regulation and function in distinct HNACC subgroups remain to be fully elucidated.

Expression of embryonal stem cell transcription factors in breast cancer: Oct4 as an indicator for poor clinical outcome and tamoxifen resistance

The transcription factors of embryonic stem cells, such as Oct4, Sox2, Nanog, Bmi1, and Klf4, are known to be associated with stemness, epithelial–mesenchymal transition and aggressive tumor behavior. This study was designed to evaluate the clinicopathological significance of their expression in breast cancer. Immunohistochemistry for Oct4, Sox2, Nanog, Bmi1, and Klf4 was performed in 319 cases of invasive breast cancer. The relationship between the expression of these markers and clinicopathologic features of the tumors, including breast cancer stem cell phenotype and epithelial–mesenchymal transition marker expression, and their prognostic value in breast cancer, were analyzed. Expression of Oct4 and Sox2 was commonly associated with high histologic grade and high Ki-67 index in the whole group and in the hormone receptor-positive subgroup. On the other hand, expression of Nanog, Bmi1, and Klf4 was inversely correlated with aggressive features of the breast cancer. Oct4 expression was associated with ALDH1 expression but not with epithelial–mesenchymal transition marker expression. In survival analysis, Oct4 expression was independently associated with poor prognosis in the whole group and in the hormone receptor-positive subgroup, but not in hormone receptor-negative subgroup. Particularly, Oct4 expression was associated with poor clinical outcome in patients with hormone receptor-positive breast cancer treated with tamoxifen. Our results indicate that Oct4 expression is associated with aggressive features, ALDH1 expression, tamoxifen resistance and poor clinical outcomes in hormone receptor-positive breast cancer, and thus may be useful as a predictive and prognostic marker in this subgroup of breast cancer.

Autocrine interleukin-23 promotes self-renewal of CD133+ ovarian cancer stem-like cells

Cancer stem cells (CSCs) are a group of cells which possess the ability of self-renewing and unlimited proliferation. And these CSCs are thought to be the cause of metastasis, recurrence and resistance. Recent study has found that pro-inflammatory cytokine and chemotactic factor mediate the self-renewing and differentiation of most of CSCs. Thus we speculate that ovarian cancer stem cells (OCSCs) can also maintain the ability of self-renewing and differentiation by releasing inflammatory factor. This report we discuss the biological characteristics and the specific molecular mechanism mediated by interleukin-23 (IL-23) and its receptor on the self-renewing of OCSCs. We found that OCSCs had high expression of IL-23 and IL-23R. IL-23 could promote the self-renewal ability of OCSCs and played a very important role to maintain the stable expression of stem cell markers in vitro. Moreover, we verified that IL-23 could maintain the potential tumorigenic of OCSCs in vivo and mediate the self-renewal ability and the formation of tumor in OCSCs by activating the signal pathways of STAT3 and NF-κB. In addition, human low differentiation tissues showed overexpression of IL-23. And IL-23 positively correlated to the expression level of CD133, Nanog and Oct4. In conclusion, Our discoveries demonstrate that autocrine IL-23 contribute to ovarian cancer malignancy through promoting the self-renewal of CD133+ ovarian cancer stem-like cells, and this suggests that IL-23 and its signaling pathway might serve as therapeutic targets for the treatment of ovarian cancer.

Phosphorylation of Sox2 at Threonine 116 is a Potential Marker to Identify a Subset of Breast Cancer Cells with High Tumorigenecity and Stem-Like Features

We have previously identified a novel phenotypic dichotomy in breast cancer (BC) based on the response to a SRR2 (Sox2 regulatory region 2) reporter, with reporter responsive (RR) cells being more tumorigenic/stem-like than reporter unresponsive (RU) cells. Since the expression level of Sox2 is comparable between the two cell subsets, we hypothesized that post-translational modifications of Sox2 contribute to their differential reporter response and phenotypic differences. By liquid chromatography-mass spectrometry, we found Sox2 to be phosphorylated in RR but not RU cells. Threonine 116 is an important phosphorylation site, since transfection of the T116A mutant into RR cells significantly decreased the SRR2 reporter luciferase activity and the RR-associated phenotype. Oxidative stress-induced conversion of RU into RR cells was accompanied by Sox2 phosphorylation at T116 and increased Sox2-DNA binding. In a cohort of BC, we found significant correlations between the proportion of tumor cells immuno-reactive with anti-phosphorylated Sox2^T116 and a high tumor grade (p = 0.006), vascular invasion (p = 0.001) and estrogen receptor expression (p = 0.032). In conclusion, our data suggests that phosphorylation of Sox2^T116 contributes to the tumorigenic/stem-like features in RR cells. Detection of phospho-Sox2^T116 may be useful in identifying a small subset of tumor cells carrying stem-like/tumorigenic features in BC.

Phase I trial to evaluate the addition of alisertib to fulvestrant in women with endocrine-resistant, ER+ metastatic breast cancer

PURPOSE

In estrogen receptor-positive (ER+) breast cancer models, activation of Aurora A kinase (AURKA) is associated with downregulation of ERα expression and resistance to endocrine therapy. Alisertib is an oral selective inhibitor of AURKA. The primary objectives of this phase I trial were to determine the recommended phase II dose (RP2D) and evaluate the toxicities and clinical activity of alisertib combined with fulvestrant in patients with ER+ metastatic breast cancer (MBC).

METHODS

In this standard 3 + 3 dose-escalation phase I study, postmenopausal patients with endocrine-resistant, ER+ MBC previously treated with endocrine therapy were assigned to one of two dose levels of alisertib (40 or 50 mg) in combination with fixed-dose fulvestrant.

RESULTS

Ten patients enrolled, of which nine were evaluable for the primary endpoint. The median patient age was 59. All patients had secondary (acquired) endocrine resistance, and all had received prior aromatase inhibitor. Six had experienced disease progression on fulvestrant. There were no severe (grade 3+) toxicities reported during cycle 1 at either dose level. The median progression-free survival time was 12.4 months (95% CI 5.3-not met), and the 6-month clinical benefit rate was 77.8% (95% CI 40.0-87.2%).

CONCLUSIONS

In patients with endocrine-resistant, ER+ MBC, alisertib in combination with fulvestrant was well tolerated. A favorable safety profile was observed. The RP2D is 50 mg twice daily on days 1-3, 8-10, and 15-17 of a 28-day cycle with standard dose fulvestrant. Promising antitumor activity was observed, including activity among patients with prior progression on fulvestrant.

Increased SOX2 expression in salivary gland carcinoma ex pleomorphic adenoma progression: an association with adverse outcome

SOX2 is a regulatory factor of embryonic stem cells that has been implicated in carcinogenesis and cancer progression. We aimed to investigate the potential role of SOX2 in the stepwise progression from pleomorphic adenoma (PA) to invasive carcinoma ex pleomorphic adenoma (CXPA), evaluating its prognostic significance as well. Thirty PAs without malignant transformation and 25 CXPAs presenting both luminal or myoepithelial differentiation (7 intracapsular and 18 extracapsular) were evaluated immunohistochemically for SOX2 expression. Of these, 24 CXPAs (96%) were positive to SOX2, being 6 intracapsular carcinomas (85.7%) and all the 18 extracapsular carcinomas (100%). Residual PA areas and PA without malignant transformation were negative. High SOX2 expression levels (> 50% of positive cells) were correlated with high histological grade (p = 0.02), brisk mitotic activity (p = 0.01), advanced pT stage (p = 0.01), tumor recurrence (p = 0.01), and development of distant metastasis (p = 0.004). Still, overall survival rates were shorter in patients with extracapsular CXPA exhibiting diffuse SOX2 expression. These results suggest that SOX2 may play an important role in carcinogenesis and progression of CXPA and is also related with prognostic indicators in CXPAs with extracapsular invasion. Although direct therapeutic intervention in SOX2 may result in unwanted complications due to its constitutive functions, strategic approach to SOX2-related pathways may provide new therapeutic opportunities for patients with invasive CXPA.

SOX2 regulates multiple malignant processes of breast cancer development through the SOX2/miR-181a-5p, miR-30e-5p/TUSC3 axis

BACKGROUND

High levels of SOX2 protein are correlated with increased dissemination of breast cancer. However, the underlying molecular mechanisms are not fully understood.

METHODS

In this study we investigate the role of SOX2 in breast cancer metastasis using multiple in vitro and in vivo assays including cell culture, shRNA-mediated knockdown, wound healing, colony formation, transwell chamber, xenograft and tail vein injection. Moreover, western blot, immunostaining, microarray and real-time PCR were used to determine the change of protein and miRNA levels. Luciferase assays were also used to evaluate activity which TUSC3 is a target of miR-181a-5p and miR-30e-5p, and the clinical survival relevance was analyzed by Kaplan-Meier analysis.

RESULTS

We identified a novel pathway involving SOX2 regulation of microRNAs to control the proliferation and migration of breast cancer cells. shRNA-mediated knockdown of SOX2 inhibits breast cancer cell expansion and migration. More importantly, we found that these changes are accompanied by significant reduction in the levels of two microRNAs, miR-181a-5p and miR-30e-5p. Overexpression of these two microRNAs leads to reduced protein levels of Tumor Suppressor Candidate 3 (TUSC3) in breast cancer cells; mutations of the potential binding sites in the 3'-UTR of TUSC3 abrogate the inhibitory effects of the microRNAs. We further found that upregulation of TUSC3 expression leads to reduced proliferation and migration of breast cancer cells. In human breast cancer samples the levels of TUSC3 protein are inversely correlated with those of SOX2 protein.

CONCLUSIONS

Taken together, our work reveals a novel SOX2-mediated regulatory axis that plays critical roles in the proliferation, migration and invasiveness of breast cancer cells. Targeting this axis may provide beneficial effect in the treatment of breast cancer.

FGFR1 is an adverse outcome indicator for luminal A breast cancers

Fibroblast growth factor receptor 1 (FGFR1) has been suggested to be the candidate gene for 8p11-12 amplification in breast cancer and its therapeutic/ prognostic value is explored. Most previous studies focused on FGFR1 gene amplification, which may not necessarily lead to protein expression. Therefore, analysis of protein level may have more clinical relevance. We evaluated FGFR1 expression in a large cohort of breast cancer by immunohistochemistry, correlated with the tumor clinic-pathologic features, biomarkers expression, and patient's survival. FGFR1 expression was associated mainly with luminal cancers, particularly luminal B subtype (23.5%; p < 0.001), and it also showed adverse prognostic impact on luminal A cancers. FGFR1 expression was associated with higher pN (p = 0.023), pT (p = 0.003) stages, lymphovascular invasion (p = 0.010), p-cadherin (p = 0.028), synaptophysin (p = 0.009) and SOX2 expression (p = 0.034) in luminal A cancers. FGFR1 expressing luminal A cancers showed a similar outcome as luminal B cancers. Multivariate Cox regression analysis demonstrated FGFR1 positive luminal A cancers to be an independently poor prognosticator for disease free survival in luminal cancers (hazard ratio = 3.341, p = 0.008). Thus FGFR1 could be useful in identifying the aggressive cases amongst heterogeneous luminal A cancers. Given the relevance of FGFR pathway in treatment resistance in luminal cancers, FGFR1 could be an important tumor biomarker and adverse prognostic factor potentially exploitable in the clinical management of luminal cancers.

Roles of sex-determining region Y-box 2 in cell pluripotency and tumor-related signaling pathways

The sex-determining region Y-box 2 (SOX2) gene, a member of the Sry-like high-mobility group box (SOX) gene family, encodes the transcription factor Sox2, which significantly contributes to the regulation of cell pluripotency. Sox2 is closely associated with early embryonic development, neural differentiation and other biological processes. An inreasing number of recent studies suggest that Sox2 exerts a positive effect on malignant tumors. According to these results, Sox2 is expected to become a novel target for cancer therapy by unveiling the mechanism through which it affects the biological behavior of tumors. Therefore, it is crucial to elucidate the detailed association of Sox2 with malignant tumors. The aim of this study was to review the role of Sox2 in pluripotency maintenance, early embryonic development and neural differentiation, as well as investigate the detailed mechanism through which Sox2 regulates cancer stem cells and tumorigenesis.

The network of pluripotency, epithelial-mesenchymal transition, and prognosis of breast cancer

Breast cancer is the leading female cancer in terms of prevalence. Progress in molecular biology has brought forward a better understanding of its pathogenesis that has led to better prognostication and treatment. Subtypes of breast cancer have been identified at the genomic level and guide therapeutic decisions based on their biology and the expected benefit from various interventions. Despite this progress, a significant percentage of patients die from their disease and further improvements are needed. The cancer stem cell theory and the epithelial-mesenchymal transition are two comparatively novel concepts that have been introduced in the area of cancer research and are actively investigated. Both processes have their physiologic roots in normal development and common mediators have begun to surface. This review discusses the associations of these networks as a prognostic framework in breast cancer.

Associations between SOX2 and miR-200b expression with the clinicopathological characteristics and prognosis of patients with glioma

The aim of the present study was to investigate the associations between microRNA (miR)-200b and sex determining region Y-box 2 (SOX2) expression with gender, age, clinical staging and pathological staging in 123 patients with glioma. The results revealed higher miR-200b expression levels in the glioma tissue than in the normal brain tissues, and a reduction in miR-200b expression with increasing pathological grading of the gliomas. Immunohistochemistry revealed a 53.7% gross expression rate of SOX2 in the glioma tissues. SOX2 and miR-200b expression levels were significantly correlated with the histological grading of the gliomas (P<0.05); however, no associations were observed with patient gender, age, pathological classification or clinical staging of the glioma (P>0.05). In patients with grade I and II gliomas, no correlation was detected between miR-200b and SOX2, while a significant correlation was observed in grade III and IV gliomas. A median 52-month follow-up revealed 1-, 3- and 5-year gross survival rates of 82.1, 50.0 and 30.7%, respectively, in the 123 patients with a glioma. Univariate analysis revealed no association between survival rate and patient age, gender, Karnofsky Performance Scale score, histological grading or clinical staging (P>0.05). However, miR-200b and SOX2 were independent prognostic factors for glioma (P<0.05). Patients with positive SOX2 expression exhibited a significantly reduced 5-year survival rate, compared with those with negative SOX2 expression (P<0.001). Furthermore, a significantly higher 5-year survival rate was observed in patients with high miR-200b expression than those with low miR-200b expression (P<0.001). The results indicated that SOX2 and miR-200b expression levels are associated with the histological grading of gliomas, but do not correlate with patient gender or age, or the pathological classification or clinical staging of the gliomas. Thus, miR-200b and SOX2 offer useful independent prognostic factors for glioma.

Bcl2 and Ki67 refine prognostication in luminal breast cancers

Combined B-cell lymphoma 2 (Bcl2) and Ki67 expression for breast cancer prognostication has been proposed recently. However, the combinatorial relationship with patient outcome, clinico-pathologic features, and various biomarkers has not been fully explored. Bcl2 and Ki67 expression were examined in a large cohort of breast cancers. Differential Bcl2 and Ki67 combinatorial analysis, particularly in luminal cancers, were evaluated with respect to the clinico-pathologic features, biomarkers profile and outcome. Combined Bcl2/Ki67 phenotypes classified by Bcl2 and Ki67 cutoffs showed a better correlation with outcome. Multivariate analysis revealed this to be an independent prognostic factor in luminal cancers. Both Ki67 and Bcl2 contributed to the prognostic implications of different subgroups defined by Bcl2/Ki67 combination phenotypes with clinico-pathologic features and biomarkers profile. Ki67low/Bcl2high cases showed better DFS (HR = 2.17, P = 0.015) and OS (HR = 3.217, P = 0.015) compared to Ki67high/Bcl2low cases. Interestingly, Ki67low/Bcl2high cases also showed better outcome than other phenotypes in grade 2 cancers (log-rank = 4.844, P = 0.028) and TNM stage 2 cancers (log-rank = 8.161, P = 0.004). This classification by Bcl2/Ki67 combination phenotypes, together with PR expression, can also refine luminal A cancers prognostication. Not all PR low luminal A cases had poorer outcome compared to the PR high luminal A cases; poor prognosis was only limited to those with also low Bcl2 (log-rank = 23.568, P < 0.001 compared to PR high Bcl2 high cases). The combined Ki67/Bcl2 phenotyping was useful in luminal cancers prognostication. It also refined prognostication in intermediate groups (grade 2 and stage 2 cancers) of luminal cancers; and aided in further classification of luminal A cancers.

Epithelial-mesenchymal transition transcription factors and miRNAs: “Plastic surgeons” of breast cancer

Growing evidence suggests that breast cancer cell plasticity arises due to a partial reactivation of epithelial-mesenchymal transition (EMT) programs in order to give cells pluripotency, leading to a stemness-like phenotype. A complete EMT would be a dead end program that would render cells unable to fully metastasize to distant organs. Evoking the EMT-mesenchymal-to-epithelial transition (MET) cascade promotes successful colonization of distal target tissues. It is unlikely that direct reprogramming or trans-differentiation without passing through a pluripotent stage would be the preferred mechanism during tumor progression. This review focuses on key EMT transcriptional regulators, EMT-transcription factors involved in EMT (TFs) and the miRNA pathway, which are deregulated in breast cancer, and discusses their implications in cancer cell plasticity. Cross-regulation between EMT-TFs and miRNAs, where miRNAs act as co-repressors or co-activators, appears to be a pivotal mechanism for breast cancer cells to acquire a stem cell-like state, which is implicated both in breast metastases and tumor recurrence. As a master regulator of miRNA biogenesis, the ribonuclease type III endonuclease Dicer plays a central role in EMT-TFs/miRNAs regulating networks. All these EMT-MET key regulators represent valuable new prognostic and predictive markers for breast cancer as well as promising new targets for drug-resistant breast cancers.