Hepatocyte growth factor disrupts cell contact and stimulates an increase in type 3 inositol triphosphate receptor expression, intracellular calcium levels, and apoptosis of rat ovarian surface epithelial cells

Inositol (1,4,5)-Trisphosphate Receptors in Invasive Breast Cancer: A New Prognostic Tool?

Simple Summary

The inositol-trisphosphate receptor (IP₃R) is a key player in physiological and pathological intracellular calcium signaling. The objective of the present study was to assess the putative value of the three IP₃R subtypes as prognostic biomarkers in breast cancer. We found that IP₃R3 is the most strongly expressed subtype in breast cancer tissue. Furthermore, IP₃R3 and IP₃R1 are significantly more expressed in invasive breast cancer tissue than in non-tumor tissue. In contrast to IP₃R1 and IP₃R2, the expression of IP₃R3 was positively correlated with prognostic factors including tumor size, regional node invasion, histologic grade, proliferation index, and hormonal status. By analyzing public databases, we found that the expression of all IP₃R subtypes is significantly correlated with the overall survival and disease-free survival of patients with breast cancer. We conclude that relative to the other two IP₃R subtypes, IP₃R3 expression is upregulated in breast cancer and is correlated with prognostic factors. We strongly believe that our results will open up new perspectives with regard to the link between IP₃Rs and breast cancer aggressiveness.

Abstract

Breast cancer is the leading cause of cancer death among women in worldwide and France. The disease prognosis and treatment differ from one breast cancer subtype to another, and the disease outcome depends on many prognostic factors. Deregulation of ion flux (especially Ca²⁺ flux) is involved in many pathophysiology processes, including carcinogenesis. Inside the cell, the inositol-trisphosphate receptor (IP₃R) is a major player in the regulation of the Ca²⁺ flux from the endoplasmic reticulum to the cytoplasm. The IP₃Rs (and particularly the IP₃R3 subtype) are known to be involved in proliferation, migration, and invasion processes in breast cancer cell lines. The objective of the present study was to evaluate the potential value of IP₃Rs as prognostic biomarkers in breast cancer. We found that expression levels of IP₃R3 and IP₃R1 (but not IP₃R2) were significantly higher in invasive breast cancer of no special type than in non-tumor tissue from the same patient. However, the IP₃R3 subtype was expressed more strongly than the IP₃R1 and IP₃R2 subtypes. Furthermore, the expression of IP₃R3 (but not of IP₃R1 or IP₃R2) was positively correlated with prognostic factors such as tumor size, regional node invasion, histologic grade, proliferation index, and hormone receptor status. In an analysis of public databases, we found that all IP₃Rs types are significantly associated with overall survival and progression-free survival in patients with breast cancer. We conclude that relative to the other two IP₃R subtypes, IP₃R3 expression is upregulated in breast cancer and is correlated with prognostic factors.

Altered Organelle Calcium Transport in Ovarian Physiology and Cancer

Calcium levels have a huge impact on the physiology of the female reproductive system, in particular, of the ovaries. Cytosolic calcium levels are influenced by regulatory proteins (i.e., ion channels and pumps) localized in the plasmalemma and/or in the endomembranes of membrane-bound organelles. Imbalances between plasma membrane and organelle-based mechanisms for calcium regulation in different ovarian cell subtypes are contributing to ovarian pathologies, including ovarian cancer. In this review, we focused our attention on altered calcium transport and its role as a contributor to tumor progression in ovarian cancer. The most important proteins described as contributing to ovarian cancer progression are inositol trisphosphate receptors, ryanodine receptors, transient receptor potential channels, calcium ATPases, hormone receptors, G-protein-coupled receptors, and/or mitochondrial calcium uniporters. The involvement of mitochondrial and/or endoplasmic reticulum calcium imbalance in the development of resistance to chemotherapeutic drugs in ovarian cancer is also discussed, since Ca²⁺ channels and/or pumps are nowadays regarded as potential therapeutic targets and are even correlated with prognosis.

The type III inositol 1,4,5-trisphosphate receptor is associated with aggressiveness of colorectal carcinoma

The inositol 1,4,5-trisphosphate receptor (InsP3R) mediates Ca(2+) signaling in epithelia and regulates cellular functions such as secretion, apoptosis and cell proliferation. Loss of one or more InsP3R isoform has been implicated in disease processes such as cholestasis. Here we examined whether gain of expression of InsP3R isoforms also may be associated with development of disease. Expression of all three InsP3R isoforms was evaluated in tissue from colorectal carcinomas surgically resected from 116 patients. Type I and II InsP3Rs were seen in both normal colorectal mucosa and colorectal cancer, while type III InsP3R was observed only in colorectal cancer. Type III InsP3R expression in the advancing margins of tumors correlated with depth of invasion, lymph node metastasis, liver metastasis, and TNM stage. Heavier expression of type III InsP3R also was associated with decreased 5-year survival. shRNA knockdown of type III InsP3R in CACO-2 colon cancer cells enhanced apoptosis, while over-expression of the receptor decreased apoptosis. Thus, type III InsP3R becomes expressed in colon cancer, and its expression level is directly related to aggressiveness of the tumor, which may reflect inhibition of apoptosis by the receptor. These findings suggest a previously unrecognized role for Ca(2+) signaling via this InsP3R isoform in colon cancer.

Activity-dependent hepatocyte growth factor expression and its role in organogenesis and cancer growth suppression

Studies by Murphy et al. have shown that neuronal stimulation can activate immediate early genes that code for transcription factors. Recent data suggest that Ca(2+) elevation in both neuronal cytoplasmic and nuclear compartments is responsible for the coupling of synaptic excitation to gene expression. Deisseroth et al. suggest that Ca(2+) influx through L-type voltage-sensitive Ca(2+) channels (VSCCs) activates cytoplasmic Ca(2+) targets such as calmodulin (CaM). The Ca(2+)-CaM complex then translocates to the nucleus leading to Ca(2+) and cAMP response element-binding protein (CREB) phosphorylation and gene expression. Reports have shown that L-type VSCCs are found on the vagus nerve. Other studies have suggested that activation of L-type VSCCs leads to a Ca(2+) store-dependent elevation of nuclear [Ca(2+)] that triggers gene expression by more direct activation of nuclear Ca(2+)/CaM-dependent protein kinase (CaMK). Moreover, nuclear transcription factors such as DREAM are themselves Ca(2+)-dependent, further supporting the importance of both nuclear and cytoplasmic Ca(2+) elevation in regulating gene expression. Our simulation studies suggest that intense synaptic stimulation in combination with amplification by release from intracellular Ca(2+) stores can produce elevations in nuclear Ca(2+) concentration and CaMK phosphorylation leading to CREB phosphorylation and gene expression. One of the downstream events would be the production of hepatocyte growth factor (HGF). HGF has trophic, repair, therapeutic or mitotic effect on kidney, pancreas, spleen, liver, lung, heart and spinal cord. These organs and systems' regeneration can be achieved by either upregulation of HGF release from the vagus nerve or upregulation of HGF production within the system (spinal cord). Conversely, inhibition of HGF release from the vagus nerve can inhibit cancer growth. Vagus nerve seems to be the nerve that nature intends to regulate organ growth and regeneration, it is very possible that other than HGF and injurin, other growth factors could be found in the vagus nerve. Electrical depolarization and hyperpolarization of the vagus nerve would be the most natural and effective way to induce organ regeneration and suppress cancer growth, respectively. A similar pathway seems to exist for different organs as HGF has trophic, repair, therapeutic or mitotic effect on different vagally innervated organs.

Early events in ovarian epithelial carcinogenesis: progress and problems in experimental approaches

The etiology and early events in the progression of epithelial ovarian carcinomas are among the least understood of all major human malignancies. There are no adequate means for early detection of these neoplasms and, as a result, they are usually diagnosed in late stages. The purpose of this review is to point out some of the peculiar problems and limitations that have hampered progress in ovarian carcinogenesis research and to summarize new approaches and recent advances in our understanding of this process. The review first presents an overview of the properties of the ovarian surface epithelium (OSE) which is thought to be the source of epithelial ovarian carcinomas, followed by a discussion of recent research based on human OSE. This includes sections on methodology for the attainment and study of OSE, investigations of OSE from women with predisposing mutations, and attempts to convert normal OSE to malignancy. This overview is followed by a discussion of the contributions, potential, and limitations of animal models. The knowledge gained by these approaches will likely lead to improvements in our ability to prevent, diagnose, and treat ovarian cancer.