Knockdown of PLC-gamma-2 and calmodulin 1 genes sensitizes human cervical adenocarcinoma cells to doxorubicin and paclitaxel

Targeting PLCG2 Suppresses Tumor Progression, Orchestrates the Tumor Immune Microenvironment and Potentiates Immune Checkpoint Blockade Therapy for Colorectal Cancer

Background: Tumor progression and limited benefits of immune checkpoint blockade (ICB) therapy have been two major challenges in the clinical management of colorectal cancer (CRC). The objective of our research was to explore the role of PLCG2 in CRC progression, tumor microenvironment, and potentiating ICB therapy. Methods: Based on bioinformatics analysis and a prospective clinical observational study, the expression, prognostic significance, and clinical relevance of PLCG2 in CRC were unveiled. The single-cell and spatial transcriptome revealed the role of PLCG2 in shaping the heterogeneity of the CRC tumor microenvironment. The biological function of PLCG2 was validated by in vivo and in vitro experiments. The underlying mechanisms were elucidated by RNA-seq, western blotting, qRT-PCR, and multicolor immunofluorescence. The multiplex immunohistochemistry and flow cytometry were adopted to clarify the immunomodulatory role of PLCG2 in facilitating CRC immune escape. The translational value of targeting PLCG2 to potentiate the efficacy of ICB therapy and synergistic therapy to improve prognosis was explored in the preclinical animal models. Results: In CRC, PLCG2 exhibited high expression levels and was strongly associated with poor prognosis and advanced clinicopathological characteristics of patients. The single-cell transcriptome shed light on its important role in cell communication and the development and differentiation of immune cells. The spatial transcriptome described the spatial distribution of PLCG2 in CRC tissues. Further mechanistic analysis demonstrated that PLCG2 could promote proliferation, invasion, metastasis, epithelial-mesenchymal transition, and cell cycle regulation and inhibit apoptosis of CRC cells via the Akt-mTOR pathway activation. Furthermore, PLCG2 was found to contribute greatly to the immunosuppressive microenvironment and enhanced immune escape as it significantly suppressed the infiltration and functional activation of CD8+ T cells and promoted the infiltration of Treg cells as well as PD-1 and PD-L1 expression. Meanwhile, knockdown of PLCG2 could potentiate the efficacy of ICB therapy. Conclusion: In summary, we have identified for the first time that PLCG2 could be considered a precise biomarker and promising therapeutic target for predicting CRC prognosis, optimizing individualized treatment, reversing CRC immune escape, and overcoming resistance to ICB therapy.

The role of PLCγ2 in immunological disorders, cancer, and neurodegeneration

Phosphatidylinositol-specific phospholipase Cγ2 (PLCγ2) is a critical signaling molecule activated downstream from a variety of cell surface receptors that contain an intracellular immunoreceptor tyrosine-based activation motif. These receptors recruit kinases such as Syk, BTK, and BLNK to phosphorylate and activate PLCγ2, which then generates 1D-myo-inositol 1,4,5-trisphosphate and diacylglycerol. These well-known second messengers are required for diverse membrane functionality including cellular proliferation, endocytosis, and calcium flux. As a result, PLCγ2 dysfunction is associated with a variety of diseases including cancer, neurodegeneration, and immune disorders. The diverse pathologies associated with PLCγ2 are exemplified by distinct genetic variants. Inherited mutations at this locus cause PLCγ2-associated antibody deficiency and immune dysregulation, in some cases with autoinflammation. Acquired mutations at this locus, which often arise as a result of BTK inhibition to treat chronic lymphocytic leukemia, result in constitutive downstream signaling and lymphocyte proliferation. Finally, a third group of PLCγ2 variants actually has a protective effect in a variety of neurodegenerative disorders, presumably by increased uptake and degradation of deleterious neurological aggregates. Therefore, manipulating PLCγ2 activity either up or down could have therapeutic benefit; however, we require a better understanding of the signaling pathways propagated by these variants before such clinical utility can be realized. Here, we review the signaling roles of PLCγ2 in hematopoietic cells to help understand the effect of mutations driving immune disorders and cancer and extrapolate from this to roles which may relate to protection against neurodegeneration.

Changes in protein expression due to metformin treatment and hyperinsulinemia in a human endometrial cancer cell line

The incidence of endometrial cancer (EC) has increased over the past years and mainly affects women above the age of 45 years. Metabolic diseases such as obesity and type II diabetes mellitus as well as associated conditions like polycystic ovary syndrome (PCOS), insulin resistance and hyperinsulinemia lead to elevated levels of circulating estrogens. Increased estrogen concentrations, in turn, further trigger the proliferation of endometrial cells and thus promote EC development and progression, especially in the absence of progesterone as seen in postmenopausal women. Elevated blood glucose levels in diabetic patients further contribute to the risk of EC development. Metformin is an insulin-sensitizing biguanide drug, commonly used in the treatment of type II diabetes mellitus, especially in obese patients. Besides its effects on glucose metabolism, metformin displayed anti-cancer effects in various cancer types, including EC. Direct anti-cancer effects of metformin target signaling pathways that are involved in cellular growth and proliferation, e.g. the AKT/PKB/mTOR pathway. Further proteins and pathways have been suggested as potential targets, but the underlying mechanism of action of metformin's anti-cancer activity is still not completely understood. In the present study, the effects of metformin on protein expression were investigated in the human EC cell line HEC-1A using an affinity proteomic approach. Cells were treated with 0.5 mmol/L metformin over a period of 7 days and changes in the expression pattern of 1,300 different proteins were compared to the expression in untreated control cells as well as insulin-treated cells. Insulin treatment (100 ng/mL) was incorporated into the study in order to implement a model for insulin resistance and associated hyperinsulinemia, conditions that are often observed in obese and diabetic patients. Furthermore, the culture medium was supplemented with 10 nmol/L ß-estradiol (E2) during treatments to mimic increased estrogen levels, a common risk factor for EC development. Based on the most prominent and significant changes in expression, a set of 80 proteins was selected and subjected to a more detailed analysis. The data revealed that metformin and insulin targeted similar pathways in the present study and mostly acted on proteins related to proliferation, migration and tumor immune response. These pathways may be affected in a tumor-promoting as well as a tumor-suppressing way by either metformin treatment or insulin supplementation. The consequences for the cells resulting from the detected expression changes were discussed in detail for several proteins. The presented data helps identify potential targets affected by metformin treatment in EC and allows for a better understanding of the mechanism of action of the biguanide drug's anti-cancer activity. However, further investigations are necessary to confirm the observations and conclusions drawn from the presented data after metformin administration, especially for proteins that were regulated in a favorable way, i.e. AKT3, CCND2, CD63, CD81, GFAP, IL5, IL17A, IRF4, PI3, and VTCN1. Further proteins might be of interest, where metformin counteracted unfavorable effects that have been induced by hyperinsulinemia.

Loss of 9p21 Regulatory Hub Promotes Kidney Cancer Progression by Upregulating HOXB13

Loss of chromosome 9p21 is observed in one-thirds of clear-cell renal cell carcinoma (ccRCC) and is associated with poorer patient survival. Unexpectedly, 9p21 LOH does not lead to decreased expression of the 9p21 tumor suppressor genes, CDKN2A and CDKN2B, suggesting alternative mechanisms of 9p-mediated tumorigenesis. Concordantly, CRISPR-mediated 9p21 deletion promotes growth of immortalized human embryonic kidney epithelial cells independently of the CDKN2A/B pathway inactivation. The 9p21 locus has a highly accessible chromatin structure, suggesting that 9p21 loss might contribute to kidney cancer progression by dysregulating genes distal to the 9p21 locus. We identified several 9p21 regulatory hubs by assessing which of the 9p21-interacting genes are dysregulated in 9p21-deleted kidney cells and ccRCCs. By focusing on the analysis of the homeobox gene 13 (HOXB13) locus, we found that 9p21 loss relieves the HOXB13 locus, decreasing HOXB13 methylation and promoting its expression. Upregulation of HOXB13 facilitates cell growth and is associated with poorer survival of patients with ccRCC. IMPLICATIONS: The results of our study propose a novel tumor suppressive mechanism on the basis of coordinated expression of physically associated genes, providing a better understanding of the role of chromosomal deletions in cancer.

Identification of Targetable Pathways in Oral Cancer Patients via Random Forest and Chemical Informatics

Treatment of head and neck cancer has been slow to change with epidermal growth factor receptor (EGFR) inhibitors, PD1 inhibitors, and taxane-/plant-alkaloid-derived chemotherapies being the only therapies approved by the U.S. Food and Drug Administration (FDA) in the last 10 years for the treatment of head and neck cancers. Head and neck cancer is a relatively rare cancer compared to breast or lung cancers. However, it is possible that existing therapies for more common solid tumors or for the treatment of other diseases could also prove effective against oral cancers. Many therapies have molecular targets that could be appropriate in oral cancer as well as the cancer in which the drug gained initial FDA approval. Also, there may be targets in oral cancer for which existing FDA-approved drugs could be applied. This study describes informatics methods that use machine learning to identify influential gene targets in patients receiving platinum-based chemotherapy, non-platinum-based chemotherapy, and genes influential in both groups of patients. This analysis yielded 6 small molecules that had a high Tanimoto similarity (>50%) to ligands binding genes shown to be highly influential in determining treatment response in oral cancer patients. In addition to influencing treatment response, these genes were also found to act as gene hubs connected to more than 100 other genes in pathways enriched with genes determined to be influential in treatment response by a random forest classifier with 20 000 trees trying 320 variables at each tree node. This analysis validates the use of multiple informatics methods to identify small molecules that have a greater likelihood of efficacy in a given cancer of interest.

siRNAs targeting multidrug transporter genes sensitise breast tumour to doxorubicin in a syngeneic mouse model

Chemotherapy, the commonly favoured approach to treat cancer is frequently associated with treatment failure and recurrence of disease as a result of development of multidrug resistance (MDR) with concomitant over-expression of drug efflux proteins on cancer cells. One of the most widely used drugs, doxorubicin (Dox) is a substrate of three different ATP-binding cassette (ABC) transporters, namely, ABCB1, ABCG2 and ABCC1, predominantly contributing to MDR phenotype in cancer. To silence these transporter-coding genes and thus enhance the therapeutic efficacy of Dox, pH-sensitive carbonate apatite (CA) nanoparticles (NPs) were employed as a carrier system to co-deliver siRNAs against these genes and Dox in breast cancer cells and in a syngeneic breast cancer mouse model. siRNAs and Dox were complexed with NPs by incubation at 37 °C and used to treat cancer cell lines to check cell viability and caspase-mediated signal. 4T1 cells-induced breast cancer mouse model was used for treatment with the complex to confirm their action in tumour regression. Smaller (∼200 nm) and less polydisperse NPs that were taken up more effectively by tumour tissue could enhance Dox chemosensitivity, significantly reducing the tumour size in a very low dose of Dox (0.34 mg/kg), in contrast to the limited effect observed in breast cancer cell lines. The study thus proposes that simultaneous delivery of siRNAs against transporter genes and Dox with the help of CA NPs could be a potential therapeutic intervention in effectively treating MDR breast cancer.

A systems medicine approach for finding target proteins affecting treatment outcomes in patients with non-Hodgkin lymphoma

Autoantibody profiling with a systems medicine approach can help identify critical dysregulated signaling pathways (SPs) in cancers. In this way, immunoglobulins G (IgG) purified from the serum samples of 92 healthy controls, 10 pre-treated (PR) non-Hodgkin lymphoma (NHL) patients, and 20 NHL patients who underwent chemotherapy (PS) were screened with a phage-displayed random peptide library. Protein-protein interaction networks of the PR and PS groups were analyzed and visualized by Gephi. The results indicated AXIN2, SENP2, TOP2A, FZD6, NLK, HDAC2, HDAC1, and EHMT2, in addition to CAMK2A, PLCG1, PLCG2, GRM5, GRIN2B, GRIN2D, CACNA2D3, and SPTAN1 as hubs in 11 and 7 modules of PR and PS networks, respectively. PR- and PS-specific hubs were evaluated in the Kyoto Encyclopedia of Genes and Genomes (KEGG) and Reactome databases. The PR-specific hubs were involved in Wnt SP, signaling by Notch1 in cancer, telomere maintenance, and transcriptional misregulation. In contrast, glutamate receptor SP, Fc receptor-related pathways, growth factors-related SPs, and Wnt SP were statistically significant enriched pathways, based on the pathway analysis of PS hubs. The results revealed that the most PR-specific proteins were associated with events involved in tumor development, while chemotherapy in the PS group was associated with side effects of drugs and/or cancer recurrence. As the findings demonstrated, PR- and PS-specific proteins in this study can be promising therapeutic targets in future studies.

Differentially expressed genes and gene networks involved in pig ovarian follicular atresia

Ovarian folliculogenesis corresponds to the development of follicles leading to either ovulation or degeneration, this latter process being called atresia. Even if atresia involves apoptosis, its mechanism is not well understood. The objective of this study was to analyze global gene expression in pig granulosa cells of ovarian follicles during atresia. The transcriptome analysis was performed on a 9,216 cDNA microarray to identify gene networks and candidate genes involved in pig ovarian follicular atresia. We found 1,684 significantly regulated genes to be differentially regulated between small healthy follicles and small atretic follicles. Among them, 287 genes had a fold-change higher than two between the two follicle groups. Eleven genes ( DKK3, GADD45A, CAMTA2, CCDC80, DAPK2, ECSIT, MSMB, NUPR1, RUNX2, SAMD4A, and ZNF628) having a fold-change higher than five between groups could likely serve as markers of follicular atresia. Moreover, automatic confrontation of deregulated genes with literature data highlighted 93 genes as regulatory candidates of pig granulosa cell atresia. Among these genes known to be inhibitors of apoptosis, stimulators of apoptosis, or tumor suppressors INHBB, HNF4, CLU, different interleukins ( IL5, IL24), TNF-associated receptor ( TNFR1), and cytochrome-c oxidase ( COX) were suggested as playing an important role in porcine atresia. The present study also enlists key upstream regulators in follicle atresia based on our results and on a literature review. The novel gene candidates and gene networks identified in the current study lead to a better understanding of the molecular regulation of ovarian follicular atresia.

Knockdown of ROS1 gene sensitizes breast tumor growth to doxorubicin in a syngeneic mouse model

Treatment of breast cancer, the second leading cause of female deaths worldwide, with classical drugs is often accompanied by treatment failure and relapse of disease condition. Development of chemoresistance and drug toxicity compels compromising the drug concentration below the threshold level with the consequence of therapeutic inefficacy. Moreover, amplification and over-activation of proto-oncogenes in tumor cells make the treatment more challenging. The oncogene, ROS1 which is highly expressed in diverse types of cancers including breast carcinoma, functions as a survival protein aiding cancer progression. Thus we speculated that selective silencing of ROS1 gene by carrier-mediated delivery of siRNA might sensitize the cancer cells to the classical drugs at a relatively low concentration. In this investigation we showed that intracellular delivery of c-ROS1-targeting siRNA using pH-sensitive inorganic nanoparticles of carbonate apatite sensitizes mouse breast cancer cells (4T1) to doxorubicin, but not to cisplatin or paclitaxel, with the highest enhancement in chemosensitivity obtained at 40 nM of the drug concentration. Although intravenous administrations of ROS1-loaded nanoparticles reduced growth of the tumor, a further substantial effect on growth retardation was noted when the mice were treated with the siRNA- and Dox-bound particles, thus suggesting that silencing of ROS1 gene could sensitize the mouse breast cancer cells both in vitro and in vivo to doxorubicin as a result of synergistic effect of the gene knockdown and the drug action, eventually preventing activation of the survival pathway protein, AKT1. Our findings therefore provide valuable insight into the potential cross-talk between the pathways of ROS1 and doxorubicin for future development of effective therapeutics for breast cancer.

Preeclampsia serum-induced collagen I expression and intracellular calcium levels in arterial smooth muscle cells are mediated by the PLC-γ1 pathway

In women with preeclampsia (PE), endothelial cell (EC) dysfunction can lead to altered secretion of paracrine factors that induce peripheral vasoconstriction and proteinuria. This study examined the hypothesis that PE sera may directly or indirectly, through human umbilical vein ECs (HUVECs), stimulate phospholipase C-γ1-1,4,5-trisphosphate (PLC-γ1-IP₃) signaling, thereby increasing protein kinase C-α (PKC-α) activity, collagen I expression and intracellular Ca²⁺ concentrations ([Ca²⁺]_i) in human umbilical artery smooth muscle cells (HUASMCs). HUASMCs and HUVECs were cocultured with normal or PE sera before PLC-γ1 silencing. Increased PLC-γ1 and IP₃ receptor (IP₃R) phosphorylation was observed in cocultured HUASMCs stimulated with PE sera (P<0.05). In addition, PE serum significantly increased HUASMC viability and reduced their apoptosis (P<0.05); these effects were abrogated with PLC-γ1 silencing. Compared with normal sera, PE sera increased [Ca²⁺]_i in cocultured HUASMCs (P<0.05), which was inhibited by PLC-γ1 and IP₃R silencing. Finally, PE sera-induced PKC-α activity and collagen I expression was inhibited by PLC-γ1 small interfering RNA (siRNA) (P<0.05). These results suggest that vasoactive substances in the PE serum may induce deposition in the extracellular matrix through the activation of PLC-γ1, which may in turn result in thickening and hardening of the placental vascular wall, placental blood supply shortage, fetal hypoxia–ischemia and intrauterine growth retardation or intrauterine fetal death. PE sera increased [Ca²⁺]_i and induced PKC-α activation and collagen I expression in cocultured HUASMCs via the PLC-γ1 pathway.

The many faces of calmodulin in cell proliferation, programmed cell death, autophagy, and cancer

Calmodulin (CaM) is a ubiquitous Ca(2+) receptor protein mediating a large number of signaling processes in all eukaryotic cells. CaM plays a central role in regulating a myriad of cellular functions via interaction with multiple target proteins. This review focuses on the action of CaM and CaM-dependent signaling systems in the control of vertebrate cell proliferation, programmed cell death and autophagy. The significance of CaM and interconnected CaM-regulated systems for the physiology of cancer cells including tumor stem cells, and processes required for tumor progression such as growth, tumor-associated angiogenesis and metastasis are highlighted. Furthermore, the potential targeting of CaM-dependent signaling processes for therapeutic use is discussed.