Altered intracellular region of MUC1 and disrupted correlation of polarity-related molecules in breast cancer subtypes

Attempt to Substitute the Oncotype DX Breast Recurrence Score® Test by Histopathological Factors and MUC1 Protein Expression

Background/Aim

Oncotype DX Breast Recurrence Score® test (ODx) is a gene profiling assay predicting the benefit of adjuvant chemotherapy for early-stage hormone receptor (HR)-positive and human epidermal growth factor receptor 2 (HER2)-negative breast cancer. Meanwhile, to avoid unnecessary financial burden on the patient, many studies have attempted to establish alternatives to ODx using conventional clinicopathological factors, but these have not yet been successful. Thus, we retrospectively investigated clinicopathological factors to establish alternatives to ODx.

Patients and Methods

Data from 114 Japanese women who underwent ODx were retrospectively examined to investigate the relationship between ODx recurrence score (RS) and clinicopathological features, including MUC1 staining patterns on immunohistochemical assessment. An RS of 0-25 was defined as low, and 26-100 as high.

Results

Ninety patients (79%) had low RS and 24 patients (21%) had high RS. Univariate analysis revealed that low tumor grade, high progesterone receptor (PgR) expression, and low Ki67 labeling index (LI) were significantly associated with low RS (p=0.025, p<0.001, and p<0.001, respectively). Tumors with an apical pattern of MUC1 staining also frequently had a low RS (p=0.024). In multivariate analysis, PgR expression and Ki67 LI were independent factors associated with RS (p<0.001, for both). When the ODx results were categorized with a combination of these two factors, only 2% of the PgR-high and Ki67-low group (one in 51 cases) had a high RS.

Conclusion

PgR expression and Ki67 LI were independent factors correlated with RS. MUC1 staining pattern also has the potential to be a useful marker. We believe that it is crucial to continue attempts to identify patients who are unlikely to benefit from ODx.

Protein S-palmitoylation modification: implications in tumor and tumor immune microenvironment

Protein S-palmitoylation is a reversible post-translational lipid modification that involves the addition of a 16-carbon palmitoyl group to a protein cysteine residue via a thioester linkage. This modification plays a crucial role in the regulation protein localization, accumulation, secretion, stability, and function. Dysregulation of protein S-palmitoylation can disrupt cellular pathways and contribute to the development of various diseases, particularly cancers. Aberrant S-palmitoylation has been extensively studied and proven to be involved in tumor initiation and growth, metastasis, and apoptosis. In addition, emerging evidence suggests that protein S-palmitoylation may also have a potential role in immune modulation. Therefore, a comprehensive understanding of the regulatory mechanisms of S-palmitoylation in tumor cells and the tumor immune microenvironment is essential to improve our understanding of this process. In this review, we summarize the recent progress of S-palmitoylation in tumors and the tumor immune microenvironment, focusing on the S-palmitoylation modification of various proteins. Furthermore, we propose new ideas for immunotherapeutic strategies through S-palmitoylation intervention.

Possible correlation of apical localization of MUC1 glycoprotein with luminal A-like status of breast cancer

Adjuvant chemotherapy has played a major role in the treatment of hormone receptor-positive breast cancer for many years. To better determine which patient subsets need adjuvant chemotherapy, various gene expression analyses have been developed, but cost-effective tools to identify such patients remain elusive. In the present report, we retrospectively investigated immunohistochemical expression and subcellular localization of MUC1 in primary tumors and examined their relationship to tumor malignancy, chemotherapy effect and patient outcomes. We retrospectively examined three patient cohorts with hormone receptor-positive/human epidermal growth factor receptor 2-negative invasive breast cancer: 51 patients who underwent 21-gene expression analysis (multi-gene assay-cohort), 96 patients who received neoadjuvant chemotherapy (neoadjuvant chemotherapy-cohort), and 609 patients whose tumor tissue was used in tissue-microarrays (tissue-microarray-cohort). The immunohistochemical staining pattern of the anti-MUC1 monoclonal antibody, Ma695, was examined in cancer tissues, and subcellular localization was determined as apical, cytoplasmic or negative. In the multi-gene assay-cohort, tumors with apical patterns had the lowest recurrence scores, reflecting lower tumor malignancy, and were significantly lower than MUC1-negative tumors (P = 0.038). In the neoadjuvant chemotherapy-cohort, there was no correlation between MUC1 staining patterns and effects of chemotherapy. Finally, in the tissue-microarray-cohort, we found that patients with apical MUC1 staining patterns had significantly longer disease-free-survival and overall survival than other patterns (P = 0.020 and 0.039, respectively). Our data suggest that an apical MUC1 staining pattern indicates luminal A-likeness. Assessment of the subcellular localization of MUC1 glycoprotein may be useful for identifying patients who can avoid adjuvant chemotherapy.

Relative Quantification of Proteins in Formalin-Fixed Paraffin-Embedded Breast Cancer Tissue Using Multiplexed Mass Spectrometry Assays

The identification of clinically relevant biomarkers represents an important challenge in oncology. This problem can be addressed with biomarker discovery and verification studies performed directly in tumor samples using formalin-fixed paraffin-embedded (FFPE) tissues. However, reliably measuring proteins in FFPE samples remains challenging. Here, we demonstrate the use of liquid chromatography coupled to multiple reaction monitoring mass spectrometry (LC-MRM/MS) as an effective technique for such applications. An LC-MRM/MS method was developed to simultaneously quantify hundreds of peptides extracted from FFPE samples and was applied to the targeted measurement of 200 proteins in 48 triple-negative, 19 HER2-overexpressing, and 20 luminal A breast tumors. Quantitative information was obtained for 185 proteins, including known markers of breast cancer such as HER2, hormone receptors, Ki-67, or inflammation-related proteins. LC-MRM/MS results for these proteins matched immunohistochemistry or chromogenic in situ hybridization data. In addition, comparison of our results with data from the literature showed that several proteins representing potential biomarkers were identified as differentially expressed in triple-negative breast cancer samples. These results indicate that LC-MRM/MS assays can reliably measure large sets of proteins using the analysis of surrogate peptides extracted from FFPE samples. This approach allows to simultaneously quantify the expression of target proteins from various pathways in tumor samples. LC-MRM/MS is thus a powerful tool for the relative quantification of proteins in FFPE tissues and for biomarker discovery.

Overexpression of Mucin 1 Suppresses the Therapeutical Efficacy of Disulfiram against Canine Mammary Tumor

Simple Summary

Canine mammary tumor is one of the most prevalent canine tumor types in China. Clinical studies showed that the high expression of mucin 1 (MUC1) protein is significantly associated with the malignancy and poor prognosis of canine mammary tumor. Therefore, it is worthwhile to investigate the expression of mucin 1 in developing treatments against canine mammary tumors. In the present study, it is demonstrated that disulfiram, an approved medication in treating human alcoholism, also has inhibitory effects on the growth of canine mammary tumor cells both in vitro and in vivo. With the overexpression of MUC1, the inhibitory effects of disulfiram decrease accordingly. Moreover, disulfiram is shown to inhibit phosphoinositide 3-kinase (PI3K)/serine/threonine protein kinase (Akt) signaling transduction, which is attenuated by MUC1 overexpression. Overall, these results indicate that the expression level of MUC1 is detrimental to determining the anti-tumor activity of disulfiram. Further consideration should be given when treating the canine mammary tumor with disulfiram or other PI3K/Akt inhibitors.

Abstract

Mucin 1 (MUC1), a transmembrane protein, is closely associated with the malignancy and metastasis of canine mammary tumors; however, the role of overexpressed MUC1 in the development of cancer cells and response to drug treatment remains unclear. To address this question, we developed a new canine mammary tumor cell line, CIPp-MUC1, with an elevated expression level of MUC1. In vitro studies showed that CIPp-MUC1 cells are superior in proliferation and migration than wild-type control, which was associated with the upregulation of PI3K, p-Akt, mTOR, Bcl-2. In addition, overexpression of MUC1 in CIPp-MUC1 cells inhibited the suppressing activity of disulfiram on the growth and metastasis of tumor cells, as well as inhibiting the pro-apoptotic effect of disulfiram. In vivo studies, on the other side, showed more rapid tumor growth and stronger resistance to disulfiram treatment in CIPp-MUC1 xenograft mice than in wild-type control. In conclusion, our study demonstrated the importance of MUC1 in affecting the therapeutical efficiency of disulfiram against canine mammary tumors, indicating that the expression level of MUC1 should be considered for clinical use of disulfiram or other drugs targeting PI3K/Akt pathway.

Inverse association of rab31 and mucin-1 (CA15-3) antigen levels in estrogen receptor-positive (ER+) breast cancer tissues with clinicopathological parameters and patients' prognosis

Dysregulated expression of rab31, a member of the large Rab protein family of the Ras superfamily of small GTPases, has been observed in several types of cancer, including breast cancer. Rab31, depending on its expression level, may regulate the switch between an invasive versus proliferative phenotype of breast cancer cells in vitro. Moreover, gene expression of rab31 is induced by the C-terminal subunit of mucin-1 (MUC1-C) and estrogen receptors (ER). To gain further insights into the clinical relevance of rab31 and mucin-1 expression in breast cancer, we analyzed the relation between rab31 and mucin-1 (CA15-3) antigen levels in detergent tissue extracts of ER-positive (ER+) tumors and clinicopathological parameters as well as patients' prognosis. No significant correlation was observed between rab31 and CA15-3 antigen levels. Elevated rab31 antigen levels in tumor tissue extracts were significantly associated with higher tumor grade (P = 0.021). Strikingly, an inverse significant association was observed for CA15-3 with tumor grade (P = 0.032). Furthermore, high rab31 antigen levels were significantly associated with a high S-phase fraction (SPF, P = 0.047), whereas a trend for lower CA15-3 antigen levels in tumor tissue displaying higher SPF was observed. High rab31 antigen levels were significantly associated with poor 5-year disease-free survival (DFS) of ER+ breast cancer patients in univariate Cox regression analysis (HR = 1.91, 95% CI = 1.14-3.17, P = 0.013). In contrast, high levels of CA15-3 antigen levels were associated with better patients' prognosis (HR = 0.56, 95% CI = 0.33-0.95, P = 0.031). In multivariable analysis, rab31 antigen levels contributed independent prognostic information for DFS when adjusted for prognostically relevant clinicopathological parameters with a HR for high versus low values of 1.97 (95% CI = 1.09-3.54, P = 0.024), whereas CA15-3 antigen levels were not significant. Our results strongly suggest that rab31 antigen levels in tumor tissue are associated with the proliferative status, and rab31 represents an independent biomarker for prognosis in ER+ breast cancer patients. Total mucin-1 (CA 15-3) levels are rather inversely associated with tumor grade and SPF, and elevated levels even indicate prolonged DFS in ER+ breast cancer patients.

Palmitoylation: a protein S-acylation with implications for breast cancer

Protein S-acylation is a reversible post-translational lipid modification that involves linkage of a fatty acid chain predominantly to a cysteine amino acid via a thioester bond. The fatty acid molecule is primarily palmitate, thus the term 'palmitoylation' is more commonly used. Palmitoylation has been found to modulate all stages of protein function including maturational processing, trafficking, membrane anchoring, signaling range and efficacy, and degradation. In breast cancer, palmitoylation has been shown to control the function of commonly dysregulated genes including estrogen receptors, the epidermal growth factor (EGF) family of receptors, and cancer stem cell markers. Importantly, palmitoylation is a critical factor controlling the formation of complexes at the plasma membrane involving tetraspanins, integrins, and gene products that are key to cell-cell communication. During metastasis, cancer cells enhance their metastatic capacity by interacting with stroma and immune cells. Although aberrant palmitoylation could contribute to tumor initiation and growth, its potential role in these cell-cell interactions is of particular interest, as it may provide mechanistic insight into metastasis, including cancer cell-driven immune modulation. Compelling evidence for a role for aberrant palmitoylation in breast cancer remains to be established. To this end, in this review we summarize emerging evidence and highlight pertinent knowledge gaps, suggesting directions for future research.

Perinatal Considerations in Women With Previous Diagnosis of Cancer

As the average age that women have their first child increases and cancer therapies improve survival, obstetricians are more likely to care for pregnant women who have survived cancer. Managing these pregnancies can be challenging, as they may be associated with higher risks of maternal and neonatal morbidity and mortality. Different types of cancer require different types of intervention, including surgery, chemotherapy, radiation, or combinations of these. Prior cancer treatments therefore present different potential complications during pregnancy. Although for most women who survive cancer carrying a pregnancy does not seem to increase mortality rates, there are some associated neonatal morbidities. The most common perinatal complication associated with pregnancy after cancer is prematurity. Women who desire pregnancy after cancer survival should not be discouraged, but appropriate counseling and follow-up should be provided.