Here, combining bioinformatics and life sciences, we first downloaded the gene expression, also with survival data related to cervical cancer patients through TCGA database, and also obtained the information of detectable secreted proteins in peripheral blood through MetazSecKB database, and obtained the related targets and signaling pathways of cervical cancer development and progression through combined analysis of difference and survival data, and detected by ELISA. The relationship between MMP3 and cervical cancer was verified by detecting the expression of MMP3 in the serum of CCA patients and normal controls, as well as pre- and postoperative cervical cancer patients. By transfecting HT-3 cells with MMP3 overexpression plasmid in vitro and inhibiting PI3K/Akt signaling pathway using wortmannin, followed by detecting apoptosis levels by TUNEL staining and expression of apoptosis-related proteins (Bcl-2, Cyt-c, Casepase3) by Western blot, to further study the relationship between MMP3- PI3K/Akt and apoptosis in CCA cells. It was found that MMP3 was identified as a biological target closely associated with cervical carcinogenesis and progression and apoptosis of cervical cancer cells, and KEGG enrichment analysis showed that MMP3 was closely associated with PI3K/Akt signaling pathway. Overexpression of MMP3 significantly inhibited cervical cancer cell apoptosis, while in vitro treatment of cervical cancer cells with wortmannin, which in turn inhibited the PI3K/Akt signaling pathway, significantly attenuated the inhibitory impact of MMP3 on cervical cancer cell apoptosis. The results suggested that MMP3 inhibits apoptosis through the PI3K/Akt signaling pathway and it was very vital in the development and progression of cervical canceit was r.
MMP3 is a member of the MMPs family of proteins, a group of proteasomes that require Zn2+, Ca2+, together with other metal ions for activation. MMPs proteins can be divided into four subclasses according to their structural domains, and they have different kinds of biological functions in animals like cell autophagy, proliferation, together with angiogenesis [8]. The proteins of MMPs in tumor tissues is consistent with the expression of different MMPs proteins. The proteins of MMPs in tumor tissues is associated with the function of different MMPs proteins together with the type of tumor. For example, MMP7 protein is selectively expressed in tumor epithelial cells, while stromal cells express stromelysin-3, stromelysin-1 and gelatinase A [9–10]. Stromelysin-3 as well as MMP13 is predominantly expressed in stromal cells in breast cancer[11], and MMP2 is expressed in malignant tumors [12]. MMP9 is expressed in brain malignant tumor cells [13]. In particular, a recent paper analyzed the expression of 24 MMPs based on patient data from 15 different cancers in the TCGA database (the Cancer Genome Atlas) and showed that MMP3 was remarkably upregulated in seven different cancer tissues, and MMP3 expression was strongly related to tumor progression [14]. In fact, positive correlations between MMP3 expression and tumor infiltration and metastasis probability have been reported in breast, colorectal, lung, and bone cancers [15–18]. Ectopic expression of MMP3 lead to extracellular matrix rearrangement (ECMR) and induce carcinogenesis of epithelia cells, which suggests the disrupted balance of signal factors could result in carcinogenesis in epithelia cells [19]. In addition, overexpression of MMP3 in breast epithelial cells causes shearing of E-cadherin and converts epithelial cells to mesenchymal cells [20–21]. Similarly, in the present study, ELISA of MMP3 in plasma of CCA patients as well as healthy volunteers showed a significant increase in MMP3 expression in the blood of CCA patients, while comparing MMP3 levels in plasma of patients before and after excisional surgery. The ELISA results showed a remarkably decrease in MMP3 expression after surgery. In addition, the results of survival curve analysis also showed that patients with MMP3 expression had higher 5-year and 10-year survival rates than those with high plasma expression.
MMP3 protein has several important biological functions, like cell growth, angiogenesis as well as cell invasion. It has been shown that MMP3 upregulates the expression of Rac1b, a homodimer of small GTPase Rac1 protein, in breast, lung, and pancreatic cancer cells, and further induces epithelial mesenchymal transition and genomic instability [22–23]. In addition, knockdown of MMP3 expression in MC-38 mouse colorectal cancer cells inhibited cell proliferation and infiltration by suppressing the Erk/κB pathway, and significantly reduced tumorigenic capacity and lung metastasis in a nude mouse model [24]. As a type of secreted protein, it was found that MMP3 in Extracellular vesicles (EVs) could enter the nucleus of recipient cells and interact with It has been found that MMP3 in EVs can enter the nucleus of recipient cells and bind to DNA and heterochromatin proteins HP1/CBXs to transactivate the Connective tissue growth factor (CTGF) gene CCN2, which causes the transformation of cells from normal to cancerous state [25–26]. EVs with high expression of MMP3 can transactivate the promoter of CCN2 gene, while those with knockdown of MMP3 in EVs can transactivate the promoter of CCN2 gene. knockdown of MMP3 expression in EVs inhibits this transactivation effect. In addition, CCN2 regulates the cell cycle by upregulating cyclin A. In malignant glioma cells, CTGF upregulates the expression of anti-apoptotic factors such as survivin, Bcl-xl and Flip [27–28]. The MMP3 protein in the nucleus also transactivates the HSP gene, which encodes a cytoprotective factor, by interacting with HP1/CBXs. Thus, MMP3 proteins in the nucleus can regulate a wide range of nuclear proteins and genes related to cell transformation. In fact, the functions of MMPs are not limited to degradation or inhibition of matrix proteins through proteasomal hydrolysis, but MMPs can regulate or increase the functions of certain matrix proteins [29]. MMP3 in EVs can activate the extracellular transduction signal TGF-β by shearing precursor proteins or degrading inhibitory factors. Many proteins can be activated by MMP3 hydrolysis, such as CCN2/ CTGF, Insulin-like growth factor binding proteins (IGFBPs), Fibroblast growth factor receptor (FGF-R), Heparin-binding epidermal growth factor (HB-EGF) and Fibroblast growth factor receptor (FGFR). Tumor necrosis factor-alpha (TNF-alpha), Fibroblast growth factor receptor 1 (FGGR1) and interleukin-1β (IL-1β) [30]. In the present study, MMP3 could affect the phosphorylation level of PI3K/Akt molecules by regulating In the present study, MMP3 could affect the cell proliferation ability of HT-3 cells by regulating the phosphorylation of PI3K/Akt molecules, which provided a new perspective on the molecular mechanism of MMP3 regulation of cancer cell proliferation process.
Recent studies have revealed that PI3K-Akt is aberrantly activated in prostate cancer cells and tissues, and that exogenous downregulation of PI3K-Akt axis expression or inhibition of PI3K-Akt axis activation can exert significant anti-tumor and anti-metastatic effects on prostate cancer [31]. Li et al. found that the PI3K/Akt pathway is closely associated with the migration and invasion of ovarian cancer cells [32]. PI3K/Akt is activated in ovarian cancer cell while inhibition of it could effectively inhibit ovarian cancer cell proliferation and facilitate tumor cell senescence and apoptosis. The expression of p-mTOR as well as p-PI3K/p-Akt was remarkably elevated in tissues and cells of cervical cancer, suggesting that PI3K-Akt is abnormally activated in cervical cancer, and exogenous inhibition of p-mTOR as well as p-PI3K/p-Akt can induce apoptosis through the mitochondrial pathway and have a significant inhibitory effect on the progression of cervical cancer [33]. The above studies illustrate that PI3K/Akt signaling pathway has closely relationship with tumor cell genesis and progression, and how to effectively inhibit PI3K/Akt signaling pathway can provide an effective strategy for the prevention and therapy of cervical carcinoma. In the present study, MMP3 could influence the PI3K/Akt signaling pathway with regulating the phosphorylation levels of PI3K and Akt proteins, thus regulating the level of apoptosis and affecting the proliferation of CCA cells.