MicroRNA-615-5p regulates the proliferation and apoptosis of breast cancer cells by targeting HSF1

Heat Shock Factor 1 Inhibition: A Novel Anti-Cancer Strategy with Promise for Precision Oncology

Heat shock factor 1 (HSF1) is a transcription factor crucial for regulating heat shock response (HSR), one of the significant cellular protective mechanisms. When cells are exposed to proteotoxic stress, HSF1 induces the expression of heat shock proteins (HSPs) to act as chaperones, correcting the protein-folding process and maintaining proteostasis. In addition to its role in HSR, HSF1 is overexpressed in multiple cancer cells, where its activation promotes malignancy and leads to poor prognosis. The mechanisms of HSF1-induced tumorigenesis are complex and involve diverse signaling pathways, dependent on cancer type. With its important roles in tumorigenesis and tumor progression, targeting HSF1 offers a novel cancer treatment strategy. In this article, we examine the basic function of HSF1 and its regulatory mechanisms, focus on the mechanisms involved in HSF1's roles in different cancer types, and examine current HSF1 inhibitors as novel therapeutics to treat cancers.

MicroRNA-455-3p inhibits osteosarcoma progression via HSF1 downregulation

OBJECTIVE

This study was conducted to dissect the role and potential mechanism of microRNA (miR)-455-3p on osteosarcoma (OS) development.

METHODS

miR-455-3p and HSF1 expression in OS tissues were detected by RT-qPCR and western blot. Later, gain- and loss-of-function assays were implemented in OS cells U-2OS and MNNG. The expression of apoptosis-related genes was measured by RT-qPCR and western blot. MTT, Transwell, scratch test, and flow cytometry were utilized to test OS cell viability, invasion, migration, and apoptosis. The targeting relationship between miR-455-3p and HSF1 was assessed with a dual-luciferase reporter gene assay. The transplantation tumor experiment in nude mice was utilized for in vivo confirmation.

RESULTS

Downregulated miR-455-3p and upregulated HSF1 were displayed in OS tissues and cells. Mechanistically, miR-455-3p negatively targeted HSF1. MiR-455-3p inhibition or HSF1 overexpression increased MNNG and U-2OS cell proliferative, invasive, and migrating capabilities, while diminishing U-2OS cell apoptosis. Moreover, HSF1 overexpression negated the impacts of miR-455-3p upregulation on OS cell proliferative, invasive, migrating, and apoptotic abilities. Likewise, overexpressing miR-455-3p curtailed the growth of transplanted OS tumors through HSF1 repression.

CONCLUSION

MiR-455-3p inhibits the development of OS cells by downregulating HSF1, highlighting the possibility of miR-455-3p as an innovative indicator of prognosis and a therapeutic target for OS.

circRNA THBS1 silencing inhibits the malignant biological behavior of cervical cancer cells via the regulation of miR-543/HMGB2 axis

Circular RNA (circRNA) THBS1 has been shown to exist as an oncogene in non-small-cell lung cancer, but its role in cervical cancer is still unclear. Our experiment aimed to uncover the functions and specific mechanism of circRNA THBS1 in cervical cancer cells. Levels of circRNA THBS1 and miR-543 in cervical cancer tissues and cell lines were assessed by RT-qPCR. starBase and dual luciferase reporter gene assay were applied for investigating the correlation between miR-543 and circRNA THBS1/HMGB2. Cell proliferation and apoptosis were evaluated by MTT and flow cytometry, respectively. Furthermore, the levels of HMGB2, E-cadherin, and N-cadherin in HeLa cells were determined by RT-qPCR and western blot analysis. Our data revealed that circRNA THBS1 was significantly upregulated and miR-543 was low expressed in cervical cancer tissues and cell lines. circRNA THBS1 interacted with miR-543 and negatively regulated miR-543 expression in HeLa cells. Silencing of circRNA THBS1 remarkably suppressed HeLa cells' viability, accelerated cells' apoptosis, and inhibited the EMT of HeLa cells, while these changes were reversed by miR-543 inhibitor. Moreover, miR-543 affected HeLa cells by targeting HMGB2. In conclusion, circRNA THBS1 silencing inhibited the malignant biological behaviors of cervical cancer cells via the regulation of miR-543/HMGB2 axis.

Targeting HSF1 for cancer treatment: mechanisms and inhibitor development

Heat Shock Factor 1 (HSF1) is a master regulator of heat shock responsive signaling. In addition to playing critical roles in cellular heat shock response, emerging evidence suggests that HSF1 also regulates a non-heat shock responsive transcriptional network to handle metabolic, chemical, and genetic stress. The function of HSF1 in cellular transformation and cancer development has been extensively studied in recent years. Due to important roles for HSF1 for coping with various stressful cellular states, research on HSF1 has been very active. New functions and molecular mechanisms underlying these functions have been continuously discovered, providing new targets for novel cancer treatment strategies. In this article, we review the essential roles and mechanisms of HSF1 action in cancer cells, focusing more on recently discovered functions and their underlying mechanisms to reflect the new advances in cancer biology. In addition, we emphasize new advances with regard to HSF1 inhibitors for cancer drug development.

Skeletal muscle HSF1 prevents insulin resistance by improving glucose utilization

The regulation of muscle glucose utilization has significant potential for the treatment of type 2 diabetes mellitus (T2DM) and obesity. Heat shock factor 1 (HSF1) is involved in cellular metabolism and regulation of muscle metabolism. However, it is unclear how HSF1 regulates muscle glucose metabolism. In the present study, the development of obesity in mice was associated with HSF1 downregulation. Serum samples and muscle biopsies were obtained from obese and healthy humans. Fasting glucose and insulin levels and the homeostasis model assessment of insulin resistance value showed that obesity was associated with insulin resistance. The skeletal muscle level of HSF1 was decreased in obese and ob/ob mice. HSF1 was selectively over-expressed in the skeletal muscles of high fat diet (HFD)-fed mice. Muscle HSF1 over-expression successfully triggered glycolytic-to-oxidative myofiber switch and increased fatty acid metabolism and insulin sensitivity in the skeletal muscles of HFD-fed mice. Moreover, HSF1 improved energy expenditure and blocked muscle accumulation of triglycerides in HFD-fed mice. Consequently, muscle HSF1 mitigated the impaired muscle insulin signaling and insulin resistance in HFD-fed mice. In conclusion, T2DM and obesity in HFD-fed mice may be treated with selective HSF1-directed programming of exercise-like effects in skeletal muscle. These findings may aid the development of a new therapeutic approach for obesity and T2DM.