Biochemistry and Cell Biology

Bovine lactoferrin and lactoferrin peptides affect endometrial and cervical cancer cell lines

Cervical, uterine, and ovarian cancers are the most common malignancies of the female genital tract worldwide. Despite advances in prevention, early diagnosis, effective screening, and treatment programs, mortality remains high. Consequently, it is important to search for new treatments. The activity of bovine lactoferrin (bLF) and LF peptides against several types of cancer has been studied; however, only a few studies report the effect of bLF and LF peptides against cervical and endometrial cancers. In this study, we explored the effect of bLF as well as LF chimera and its constituent peptides LFcin17–30 and LFampin265–284 on the viability of cervical (HeLa, SiHa) and endometrial (KLE, HEC-1A) cancer cell lines. Cell proliferation was quantified with an MTT assay, cell morphological changes and damage were determined by Giemsa and phalloidin-TRITC and DAPI staining, and apoptotic and necrotic cells were identified by Alexa Fluor® 488 Annexin V and propidium iodide staining. Additionally, the effect of combinations of bLF and LF peptides with cisplatin was assessed. bLF and LF peptides inhibited the proliferation of uterine cancer cells and caused cellular morphological changes and damage to cell monolayers. bLF induced apoptosis, LFcin17–30 and LFampin265–284 induced apoptosis and necrosis, and LF chimera induced necrosis. Additionally, bLF and LF chimera showed an additive interaction with cisplatin against uterine cancer cells.

Divergent ERα co-factor landscapes in gynecological cancers: implications for disease progression and therapy

Estrogen receptor alpha (ERα) is an established biomarker for breast tumors, the loss of which is associated with poor cancer progression. Over 70% of breast cancers express ERα and targeting this protein has helped stem the progress of breast cancer. Therefore, it is paradoxical that only a small fraction of patients with ovarian and uterine cancers, which express ERα, are insensitive to antiestrogenic therapies. We propose the hypothesis that ERα association with different cofactors dictates the susceptibility of these cancers to therapies. To support this hypothesis, we analyzed data from cBioportal patient samples and showed that a strong positive correlation exists between ERα and its cofactors GATA3 and FOXA1 in breast cancer, but not in ovarian and uterine cancers. We further show that ERα genomic localization differs in the three cancer types, using available ChIP-seq datasets. Together, our analyses suggest that both localization and the nature of co-factors might be relevant for driving ERα-dependent cancer progression in different cell environments. We further discuss potential mechanisms for these differences in this commentary.

Upregulation of bromodomain PHD finger transcription factor in ovarian cancer and its critical role for cancer cell proliferation and survival

Bromodomain PHD finger transcription factor (BPTF) is a core subunit of the nucleosome-remodeling factor (NURF) complex, which plays an important role in the development of several cancers. However, it is unknown whether BPTF regulates the progression of ovarian cancer (OC). To investigate this, we measured the relative expression levels of BPTF in OC cell lines and tissues using Western blot and immunohistochemistry, respectively, and the results were analyzed using the χ2 test. We also examined the effects from BPTF knockdown on the proliferation, migration, invasiveness, and apoptosis of OC cell lines. Mechanistic studies revealed that these effects were achieved through simultaneous modulation of multiple signaling pathways. We found that BPTF was highly expressed in OC cell lines and tissues compared with a normal human ovarian epithelial cell line and non-cancerous tissues (P < 0.05). These results are also supported by the public RNA-seq data. BPTF overexpression was correlated with a poor prognosis for OC patient survival (P < 0.05). In vitro experiments revealed that the downregulation of BPTF inhibited OC cell proliferation, colony formation, migration, and invasiveness, and induced apoptosis. BPTF knockdown also affected the epithelial–mesenchymal transition (EMT) signaling pathways and induced the cleavage of apoptosis-related proteins. Consequently, BPTF plays a critical role in OC cell survival, and functions as a potential therapeutic target for OC.

Knockdown of E-cadherin induces cancer stem-cell-like phenotype and drug resistance in cervical cancer cells

Cervical cancer is one of the leading causes of mortality amongst women in developing countries, and resistance to therapy is the main reason for treatment failure. Recent advances suggest that cancer stem cells (CSCs) are critically involved in regulating the chemo-resistant behavior of cervical cancer cells. In our study, cells with the CSC phenotype were isolated, and we examined the expression levels of stem cell markers and genes associated with epithelial–mesenchymal transition (EMT) using different assays. However, the cells with the CSC phenotype could not be cultured for further cytotoxicity studies, so we established a model of CSC in cervical cancer cells. We performed siRNA-mediated knockdown of E-cadherin in these cells, and studied them for EMT-associated stem-cell-like properties. We also performed dose-dependent cell viability assays using clinically relevant drugs such as cisplatin, cyclopamine, and GANT58 to analyze the drug resistant behavior of these cancer cells. We found that knockdown of E-cadherin induces EMT in cervical cancer cells, imparting stem-cell like characteristics along with enhanced tumorsphere formation, cell migration, invasiveness, and drug resistance. This is the first study to establish a CSC model in cervical cancer cells by knockdown of E-cadherin, which can be used to develop anti-cancer therapies.

AKT1 participates in ferroptosis vulnerability by driving autophagic degradation of FTH1 in cisplatin-resistant ovarian cancer

Resistance to cisplatin (DDP)-based chemotherapy is an important reason for the failure of ovarian cancer treatment. However, tumor cells resistant to chemotherapy may expose vulnerability to other cell death pathways. Here, we found that DDP-resistant ovarian cancer cells are more susceptible to erastin-induced ferroptosis. It should be noted that this vulnerability does not depend on the weakening of classical ferroptosis defense proteins, but is caused by the reduction of ferritin heavy chain (FTH1). DDP-resistant ovarian cancer cells maintain a high level of autophagy to escape the pressure of chemotherapy, which ultimately leads to increased autophagic degradation of FTH1. We further revealed that the loss of AKT1 was the reason for the increased autophagy level of DDP-resistant ovarian cancer cells. Our study provides new insights into reversing DDP resistance in ovarian cancer by targeting ferroptosis pathway, and AKT1 may be a molecular marker of susceptibility to ferroptosis.

Nisin induces apoptosis in cervical cancer cells via reactive oxygen species generation and mitochondrial membrane potential changes

Nisin, an antimicrobial peptide produced by Lactococcus lactis, is widely used as a safe food preservative and has recently attracted the attention of researchers as a potential anticancer agent. The cytotoxicity of nisin against human cervical cancer cell lines (HeLa), human ovarian carcinoma cell lines (OVCAR-3 and SK-OV-3), and human umbilical vein endothelial cells (HUVECs) was evaluated using an MTT assay. The apoptotic effect of nisin was identified by Annexin-V/propidium iodide assay, which was further confirmed by western blotting analysis, mitochondrial membrane potential (ΔΨm) analysis, and reactive oxygen species (ROS) assay. The MTT assay showed concentration-dependent cytotoxicity of nisin towards cancer cell lines, with IC50 values of 11.5–23 µM, but less toxicity against normal endothelial cells. Furthermore, the treatment of cervical cancer cells with 12 µM nisin significantly (P < 0.05) increased the Bax/Bcl-2 ratio (4.9 fold), reduced ΔΨm (70%), and elevated ROS levels (1.7 fold). These findings indicate that nisin may have anticancer and apoptogenic activities through mitochondrial dysfunction and oxidative stress damage in cervical cancer cells.

Cholecalciferol induces apoptosis via autocrine metabolism in epidermoid cervical cancer cells

The anti-cancer effects of vitamin D are of fundamental interest. Cholecalciferol is sequentially hydroxylated endogenously to calcidiol and calcitriol. Here, SiHa epidermoid cervical cancer cells were treated with cholecalciferol (10–2600 nmol/L). Cell count and viability were assayed using Crystal Violet and Trypan Blue, respectively. Apoptosis was assessed using flow cytometry for early and late biomarkers along with brightfield microscopy and transmission electron microscopy. Autocrine vitamin D metabolism was analysed by reverse transcription-quantitative PCR and immunoblotting for activating enzymes: 25-hydroxylases (CYP2R1 and CYP27A1) and 1α-hydroxylase (CYP27B1), the catabolic 24-hydroxylase (CYP24A1), and the vitamin D receptor (VDR). Data were analysed using one-way ANOVA and Bonferroni post-hoc test, and p < 0.05 was considered significant. After cholecalciferol, cell count ( p = 0.011) and viability ( p < 0.0001) decreased, apoptotic biomarkers were positive, mitochondrial membrane potential decreased ( p = 0.0145), and phosphatidylserine externalisation ( p = 0.0439), terminal caspase activity ( p = 0.0025), and nuclear damage ( p = 0.004) increased. Microscopy showed classical features of apoptosis. Gene and protein expression were concordant. Immunoblots revealed increased CYP2R1 ( p = 0.021), VDR ( p = 0.04), and CYP24A1 ( p = 0.0274) and decreased CYP27B1 ( p = 0.031). The authors conclude that autocrine activation of cholecalciferol to calcidiol may mediate VDR signalling of growth inhibition and apoptosis in SiHa cells.

TRIM46 promotes chemoresistance of ovarian cancer via activating PHLPP2/PI3K/AKT pathway

Ovarian cancer is one of the most common and lethal malignancy tumors in women. Chemoresistance is one of the main reasons for ovarian cancer relapsing. Understanding the regulatory mechanisms of chemoresistance generation is critical to develop novel therapeutic strategies. Here, we found that TRIM46 was upregulated in ovarian cancer cells and tissues with chemoresistance and associated with poor outcomes. Functional assays showed that TRIM46 promoted cisplatin (CDDP) chemoresistance. Furthermore, TRIM46 interacts with PI3K/AKT pathway inactivator pleckstrin homology domain leucine-rich repeat protein phosphatase 2 (PHLPP2) and downregulated PHLPP2 level. Treating with PI3K/AKT pathway inhibitor significantly reversed the effects of TRIM46-overexpressing on chemoresistance. In summary, our study reveals that TRIM46 promoted chemoresistance via downregulating PHLPP2, leading to activating PI3K/AKT pathway. This study provides a novel potential target for ovarian cancer therapy.

Unveiling stem-like traits and chemoresistance mechanisms in ovarian cancer cells through the TGFβ1-PITX2A/B signaling axis

Ovarian cancer (OC) is the deadliest gynecological malignancy, having a high mortality rate due to its asymptomatic nature, chemoresistance, and recurrence. However, the proper mechanistic knowledge behind these phenomena is still inadequate. Cancer recurrence is commonly observed due to cancer stem cells which also show chemoresistance. We aimed to decipher the molecular mechanism behind chemoresistance and stemness in OC. Earlier studies suggested that PITX2, a homeobox transcription factor and, its different isoforms are associated with OC progression upon regulating different signaling pathways. Moreover, they regulate the expression of drug efflux transporters in kidney and colon cancer, rendering chemoresistance properties in the tumor cell. Considering these backgrounds, we decided to look for the role of PITX2 isoforms in promoting stemness and chemoresistance in OC cells. In this study, PITX2A/B has been shown to promote stemness and to enhance the transcription of ABCB1. PITX2 has been discovered to augment ABCB1 gene expression by directly binding to its promoter. To further investigate the regulatory mechanism of PITX2 gene expression, we found that TGFβ signaling could augment the PITX2A/B expression through both SMAD and non-SMAD signaling pathways. Collectively, we conclude that TGFβ1-activated PITX2A/B induces stem-like features and chemoresistance properties in the OC cells.

TRIM3 modulates cisplmatin-resistant of cervical squamous cell carcinoma via endoplasmic reticulum stress signaling in vitro

TRIM3 is widely recognized as a tumor suppressor gene. However, its precise role in cervical squamous cell carcinoma (CESC) remains elusive. Here, we observed a significant decrease in the expression of TRIM3 in CESC cells. Overexpression of TRIM3 suppresses cell proliferation and clonal formation. Through the establishment of cisplatin (cDDP)-resistant CESC cell lines, we discovered that the expression of TRIM3 was further downregulated in cDDP-resistant cells, while overexpression of TRIM3 enhanced cellular sensitivity to cDDP. Mechanistic investigations revealed that TRIM3 directly interacts with GRP78, a crucial protein involved in endoplasmic reticulum stress (ERS) pathway, promoting its ubiquitination degradation. Under cDDP treatment, the overexpression of TRIM3 in cDDP-resistant cells suppressed cell proliferation and downregulated the expression of drug-resistant genes, while simultaneously enhancing the activation of apoptosis signaling pathways. However, co-expression of TRIM3 and GRP78 restored cellular sensitivity to cDDP back to normal levels. Consequently, overexpressing TRIM3 in drug-resistant cells facilitates PERK activation and subsequent induction of apoptosis through inhibition of GRP78, ultimately suppressing drug resistance and inducing apoptosis in CESC cells. In conclution, our study suggests that the TRIM3/GRP78 axis regulates cDDP resistance in CESC cells by modulating the downstream apoptotic pathway of ERS.

hCINAP is potentially a direct target gene of HIF-1 and is required for hypoxia-induced EMT and apoptosis in cervical cancer cells

The early metastasis of cervical cancer is a multistep process requiring the cancer cells to adapt to the signal input from different tissue environments, including hypoxia. Hypoxia-induced epithelial-to-mesenchymal transition (EMT) plays a critical role in the ability to invade surrounding tissues. However, the molecular mechanisms underlying EMT in cervical cancer remain to be elucidated. Herein, we show that hypoxia-inducible factor-1alpha (HIF-1α) and aryl hydrocarbon receptor nuclear translocator (ARNT) are recruited to the human coilin-interacting nuclear ATPase protein (hCINAP) promoter and initiate hCINAP expression in hypoxia. Ablation of hCINAP decreased the migratory capacity and EMT of cervical cancer cells under hypoxic conditions. Furthermore, hCINAP regulated EMT through the Akt–mTOR signaling pathway, and inhibits hypoxia-induced p53-dependent apoptosis. Our data collectively show that hCINAP may have essential roles in the metastasis of cervical cancer and could be a potential target for curing cervical cancer.

LINP1 promotes the progression of cervical cancer by scaffolding EZH2, LSD1, and DNMT1 to inhibit the expression of KLF2 and PRSS8

There is a growing body of evidence indicating that long non-coding RNAs (lncRNAs) are associated with a variety of cancers. LncRNA LINP1 has been shown to be a key factor in tumor malignancy. However, the role of LINP1 in cervical cancer (CC) it is unclear. In our research, we found that the levels of LINP1 were significantly elevated in CC tissues by comparison with adjacent normal tissue. Further, the expression level of LINP1 was upregulated in CC cells compared with healthy human cervical epithelial cell lines (HUCEC). Surprisingly, we found that downregulation of LINP1 significantly reduced the proliferation of CC cells and promoted apoptosis. Additionally, downregulation of LINP1 significantly decreased CC tumor growth in vivo. Further, we observed that LINP1 recruits EZH2, LSD1, and DNMT1, thereby reducing the expression of KLF2 and PRSS8. The results from our qRT–PCR analyses showed that silencing LINP1 uprgulated the expression of KLF2 and PRSS8 in CC cells. The results from our loss-of-function assays showed that upregulation of KLF2 and PRSS8 inhibits cell proliferation and boosts cell apoptosis in CC. We also found that inhibition of KLF2 and PRSS8 reversed the inhibitory effect on cell proliferation associated with silencing LINP1. In short, LINP1 facilitates the progression of CC by suppressing KLF2 and PRSS8, and thus could provide a promising target for CC therapy.