Epigenetic Modulation of SPCA2 Reverses Epithelial to Mesenchymal Transition in Breast Cancer Cells

Recent progress of mechanosensitive mechanism on breast cancer

The mechanical environment is important for tumorigenesis and progression. Tumor cells can sense mechanical signals by mechanosensitive receptors, and these mechanical signals can be converted to biochemical signals to regulate cell behaviors, such as cell differentiation, proliferation, migration, apoptosis, and drug resistance. Here, we summarized the effects of the mechanical microenvironment on breast cancer cell activity, and mechanotransduction mechanism from cellular microenvironment to cell membrane, and finally to the nucleus, and also relative mechanosensitive proteins, ion channels, and signaling pathways were elaborated, therefore the mechanical signal could be transduced to biochemical or molecular signal. Meanwhile, the mechanical models commonly used for biomechanics study in vitro and some quantitative descriptions were listed. It provided an essential theoretical basis for the occurrence and development of mechanosensitive breast cancer, and also some potential drug targets were proposed to treat such disease.

LINC01116 affects patient survival differently and is dissimilarly expressed in ER+ and ER- breast cancer samples

BACKGROUND

Breast cancer is the most commonly detected cancer and one of the leading causes of cancer mortality. Emerging evidence supports that aberrant expression of lncRNAs is correlated with tumor progression and various aspects of tumor development.

AIM

This study aimed to evaluate the expression pattern of LINC01116 in breast cancer tissues and investigate the impact of LINC01116 on patients' survival.

METHODS AND RESULTS

Microarray and qRT-PCR data analysis were performed, and the KM-plotter database was used in this study. In addition, the gain of function approach was performed to examine the effect of LINC01116 on breast cancer cells in-vitro. The results exhibited that LINC01116 is meaningfully upregulated in the ER+ tumor specimens compared to the ER- ones. Also, relative to normal tissues, the expression of LINC01116 in ER+ and ER- tumor tissues significantly increased and decreased, respectively. ROC curve analysis revealed the power of LINC01116 in distinguishing ER+ from ER- samples. Additionally, the Kaplan-Meier survival analysis showed that the LINC01116 expression positively correlates with survival probability in all as well as ER+ patients. However, this correlation was negative in ER- patients. Furthermore, our results showed that the overexpression of LINC01116 induces TGF-β signaling in ER- cells (MDA-MB-231), and microarray data analysis revealed that LINC01116 is significantly upregulated in 17β-Estradiol treated MCF7 cells.

CONCLUSION

In conclusion, our results suggest that LINC01116 can be a potential biomarker in distinguishing ER+ and ER- tissues and has different effects on patients' survival based on ER status by affecting TGF-β and ER signaling.

Intersection between calcium signalling and epithelial-mesenchymal plasticity in the context of cancer

Epithelial-mesenchymal transition (EMT) is a form of cellular phenotypic plasticity and is considered a crucial step in the progression of many cancers. The calcium ion (Ca²⁺) acts as a ubiquitous second messenger and is implicated in many cellular processes, including cell death, migration, invasion and more recently EMT. Throughout this review, the complex interplay between Ca²⁺ signalling and EMT will be explored. An overview of the Ca²⁺ pathways that are remodelled as a consequence of EMT is provided and the role of Ca²⁺ signalling in regulating EMT and its significance is considered. Ca²⁺ signalling pathways may represent a therapeutic opportunity to regulate EMT. However, as will be described in this review, the complexity of these signalling pathways represents significant challenges that must be considered if Ca²⁺ signalling is to be manipulated with the aim of therapeutic intervention in cancer.

Transcriptional Basis of Ca2+ Remodeling Reversal Induced by Polyamine Synthesis Inhibition in Colorectal Cancer Cells

Colorectal cancer (CRC) is associated with mutations in APC/Wnt leading to c-myc activation and the overexpression of ODC1, the limiting step in polyamine synthesis. CRC cells also display a remodeling of intracellular Ca²⁺ homeostasis that contributes to cancer hallmarks. As polyamines may modulate Ca²⁺ homeostasis during epithelial tissue repair, we investigated whether polyamine synthesis inhibition may reverse Ca²⁺ remodeling in CRC cells and, if so, the molecular basis for this reversal. To this end, we used calcium imaging and transcriptomic analysis in normal and CRC cells treated with DFMO, an ODC1 suicide inhibitor. We found that polyamine synthesis inhibition partially reversed changes in Ca²⁺ homeostasis associated with CRC, including a decrease in resting Ca²⁺ and SOCE along with an increased Ca²⁺ store content. We also found that polyamine synthesis inhibition reversed transcriptomic changes in CRC cells without affecting normal cells. Specifically, DFMO treatment enhanced the transcription of SOCE modulators CRACR2A; ORMDL3; and SEPTINS 6, 7, 8, 9, and 11, whereas it decreased SPCA2, involved in store-independent Orai1 activation. Therefore, DFMO treatment probably decreased store-independent Ca²⁺ entry and enhanced SOCE control. Conversely, DFMO treatment decreased the transcription of the TRP channels TRPC1 and 5, TRPV6, and TRPP1 while increasing TRPP2, thus probably decreasing Ca²⁺ entry through TRP channels. Finally, DFMO treatment enhanced the transcription of the PMCA4 Ca²⁺ pump and mitochondrial channels MCU and VDAC3 for enhanced Ca²⁺ extrusion through the plasma membrane and mitochondria. Collectively, these findings suggested the critical role of polyamines in Ca²⁺ remodeling in colorectal cancer.

CRAC and SK Channels: Their Molecular Mechanisms Associated with Cancer Cell Development

Cancer represents a major health burden worldwide. Several molecular targets have been discovered alongside treatments with positive clinical outcomes. However, the reoccurrence of cancer due to therapy resistance remains the primary cause of mortality. Endeavors in pinpointing new markers as molecular targets in cancer therapy are highly desired. The significance of the co-regulation of Ca²⁺-permeating and Ca²⁺-regulated ion channels in cancer cell development, proliferation, and migration make them promising molecular targets in cancer therapy. In particular, the co-regulation of the Orai1 and SK3 channels has been well-studied in breast and colon cancer cells, where it finally leads to an invasion-metastasis cascade. Nevertheless, many questions remain unanswered, such as which key molecular components determine and regulate their interplay. To provide a solid foundation for a better understanding of this ion channel co-regulation in cancer, we first shed light on the physiological role of Ca²⁺ and how this ion is linked to carcinogenesis. Then, we highlight the structure/function relationship of Orai1 and SK3, both individually and in concert, their role in the development of different types of cancer, and aspects that are not yet known in this context.

Targeting epigenetic regulators for inflammation: Mechanisms and intervention therapy

Emerging evidence indicates that resolution of inflammation is a critical and dynamic endogenous process for host tissues defending against external invasive pathogens or internal tissue injury. It has long been known that autoimmune diseases and chronic inflammatory disorders are characterized by dysregulated immune responses, leading to excessive and uncontrol tissue inflammation. The dysregulation of epigenetic alterations including DNA methylation, posttranslational modifications to histone proteins, and noncoding RNA expression has been implicated in a host of inflammatory disorders and the immune system. The inflammatory response is considered as a critical trigger of epigenetic alterations that in turn intercede inflammatory actions. Thus, understanding the molecular mechanism that dictates the outcome of targeting epigenetic regulators for inflammatory disease is required for inflammation resolution. In this article, we elucidate the critical role of the nuclear factor‐κB signaling pathway, JAK/STAT signaling pathway, and the NLRP3 inflammasome in chronic inflammatory diseases. And we formulate the relationship between inflammation, coronavirus disease 2019, and human cancers. Additionally, we review the mechanism of epigenetic modifications involved in inflammation and innate immune cells. All that matters is that we propose and discuss the rejuvenation potential of interventions that target epigenetic regulators and regulatory mechanisms for chronic inflammation‐associated diseases to improve therapeutic outcomes.

Secretory pathway Ca2+-ATPase SPCA2 regulates mitochondrial respiration and DNA damage response through store-independent calcium entry

A complex interplay between the extracellular space, cytoplasm and individual organelles modulates Ca2+ signaling to impact all aspects of cell fate and function. In recent years, the molecular machinery linking endoplasmic reticulum stores to plasma membrane Ca2+ entry has been defined. However, the mechanism and pathophysiological relevance of store-independent modes of Ca2+ entry remain poorly understood. Here, we describe how the secretory pathway Ca2+-ATPase SPCA2 promotes cell cycle progression and survival by activating store-independent Ca2+ entry through plasma membrane Orai1 channels in mammary epithelial cells. Silencing SPCA2 expression or briefly removing extracellular Ca2+ increased mitochondrial ROS production, DNA damage and activation of the ATM/ATR-p53 axis leading to G0/G1 phase cell cycle arrest and apoptosis. Consistent with these findings, SPCA2 knockdown confers redox stress and chemosensitivity to DNA damaging agents. Unexpectedly, SPCA2-mediated Ca2+ entry into mitochondria is required for optimal cellular respiration and the generation of mitochondrial membrane potential. In hormone receptor positive (ER+/PR+) breast cancer subtypes, SPCA2 levels are high and correlate with poor survival prognosis. We suggest that elevated SPCA2 expression could drive pro-survival and chemotherapy resistance in cancer cells, and drugs that target store-independent Ca2+ entry pathways may have therapeutic potential in treating cancer.

Expression and associated epigenetic mechanisms of the Ca2+-signaling genes in breast cancer subtypes and epithelial-to-mesenchymal transition

Breast cancer-associated deaths are related mainly to specific molecular subtypes and the presence of metastasis. The Epithelial-to-Mesenchymal Transition (EMT) and Ca²⁺ signaling pathways are involved in breast cancer metastasis, and they are regulated in part by epigenetic mechanisms. Moreover, activation of EMT modulates Ca²⁺ concentration and in turn, Ca²⁺ signaling regulates the expression of EMT markers. Also, activation of Ca²⁺ signaling genes with epigenetic inhibitors reverts the EMT. Thus, Ca²⁺ signaling might have an important role in breast cancer metastasis and EMT, particularly through the epigenetic regulation of genes involved in its signaling. However, little is known due to that an estimate of 1670 genes participate in the Ca²⁺ signaling and only a few genes have been studied. Here, we aimed to explore the expression of all genes involved in Ca²⁺ signaling in all breast cancer subtypes and EMT, and whether modulation of epigenetic mechanisms is related to their expression. Several genes of the Ca²⁺ signaling are altered in all breast cancer subtypes, being the cadherins and voltage channels the most frequent altered genes. Also, DNA methylation and histone posttranslational modifications showed a good correlation with their altered expression. The expression of the cadherins and voltage channels is also modulated during breast EMT, and ATAC-seq results suggest that chromatin rearrangement at their promoter is involved. In conclusion, the expression of the genes involved in Ca²⁺ signaling is altered in all breast cancer subtypes and during EMT, and epigenetic mechanisms are an attractive target to regulate their expression.