Knockdown of B7H6 inhibits tumor progression in triple-negative breast cancer

Cooperative Treatment of Gastric Cancer Using B7-H7 siRNA and Docetaxel; How Could They Modify Their Effectiveness?

Purpose

Despite the high prevalence of gastric cancer (GC), drug resistance is a major problem for effective chemotherapy. B7-H7 is a novel member of the B7 superfamily and is expressed in most common cancers. However, the role of B7-H7 on the aggressiveness of GC and chemosensitivity has remained unknown. Therefore, this study was designed to assess the effect of B7-H7 suppression using small interference RNA (siRNA) in combination with docetaxel on GC cells.

Methods

MTT test was applied to determine the IC50 of docetaxel and the combined effect of B7-H7 siRNA and docetaxel on the viability of the MKN-45 cells. To determine B7-H7, BCL-2, BAX, and caspase-3-8-9 genes expression, qRT-PCR was performed. Furthermore, flow cytometry was applied to evaluate apoptosis and the cell cycle status. Finally, to evaluate the effect of this combination therapy on migratory capacity and colony-forming ability, wound healing assay and colony formation test were employed, respectively.

Results

B7-H7 suppression increased the chemo-sensitivity of MKN-45 cells to docetaxel. The expression of B7-H7 mRNA was reduced after using B7-H7 siRNA and docetaxel in MKN-45 GC cells. Also, B7-H7 suppression alongside docetaxel reduced cell migration and colony formation rate, arrested the cell cycle at the G2-M phase, and induced apoptosis by modulating the expression of apoptotic target genes.

Conclusion

B7-H7 plays a significant role in the chemo-sensitivity and pathogenesis of GC. Therefore, B7-H7 suppression, in combination with docetaxel, may be a promising therapeutic approach in treating GC.

B7H6 Serves as a Negative Prognostic Marker and an Immune Modulator in Human Pancreatic Cancer

Pancreatic cancer (PC), the third leading cause of cancer-related death in the U.S., is frequently found too late to be cured by traditional chemotherapy. Expression of B7 homolog 6 (B7H6), a member of the B7 family of immunoreceptors, has been found in PC and several other cancers. B7H6 is a ligand for cytotoxicity triggering receptor 3 (NKp30), which is expressed on NK cells. Here, we demonstrate that B7H6 can be detected in PC tissues but not normal organs. Its expression in patients associated significantly with tumor differentiation grade and lymphatic metastasis. The soluble form of B7H6 was detected in the PC patients’ sera, and its concentration associated with tumor differentiation grade and tumor, node, metastasis (TNM) stages. Also, higher levels of B7H6 in PC patients’ malignant tissues or serum correlated with shorter overall survival. In vitro, downregulation of B7H6 by CRISPR/Cas9 or siRNA technology had no significant impact on the viability or mobility of PC cells. Instead, knocking out B7H6 sensitized PC cells to NK-mediated cytotoxicity and cytokine production. These results indicate that B7H6 not only serves as a negative prognostic marker but also acts as an immune modulator in PC.

Perception of breast cancer risk factors: Dysregulation of TGF-β/miRNA axis in Pakistani females

Breast cancer poses a serious health risk for women throughout the world. Among the Asian population, Pakistani women have the highest risk of developing breast cancer. One out of nine women is diagnosed with breast cancer in Pakistan. The etiology and the risk factor leading to breast cancer are largely unknown. In the current study the risk factors that are most pertinent to the Pakistani population, the etiology, molecular mechanisms of tumor progression, and therapeutic targets of breast cancer are studied. A correlative, cross-sectional, descriptive, and questionnaire-based study was designed to predict the risk factors in breast cancer patients. Invasive Ductal Carcinoma (90%) and grade-II tumor (73.2%) formation are more common in our patient’s data set. Clinical parameters such as mean age of 47.5 years (SD ± 11.17), disturbed menstrual cycle (> 2), cousin marriages (repeated), and lactation period (< 0.5 Y) along with stress, dietary and environmental factors have an essential role in the development of breast cancer. In addition to this in silico analysis was performed to screen the miRNA regulating the TGF-beta pathway using TargetScanHuman, and correlation was depicted through Mindjet Manager. The information thus obtained was observed in breast cancer clinical samples both in peripheral blood mononuclear cells, and biopsy through quantitative real-time PCR. There was a significant dysregulation (**P>0.001) of the TGF-β1 signaling pathway and the miRNAs (miR-29a, miR-140, and miR-148a) in patients’ biopsy in grade and stage specifically, correlated with expression in blood samples. miRNAs (miR-29a and miR-140, miR-148a) can be an effective diagnostic and prognostic marker as they regulate SMAD4 and SMAD2 expression respectively in breast cancer blood and biopsy samples. Therefore, proactive therapeutic strategies can be devised considering negatively regulated cascade genes and amalgamated miRNAs to control breast cancer better.

Beyond Programmed Death-Ligand 1: B7-H6 Emerges as a Potential Immunotherapy Target in SCLC

INTRODUCTION

The programmed death-ligand 1 (PD-L1) immune checkpoint inhibitors, atezolizumab and durvalumab, have received regulatory approval for the first-line treatment of patients with extensive-stage SCLC. Nevertheless, when used in combination with platinum-based chemotherapy, these PD-L1 inhibitors only improve overall survival by 2 to 3 months. This may be due to the observation that less than 20% of SCLC tumors express PD-L1 at greater than 1%. Evaluating the composition and abundance of checkpoint molecules in SCLC may identify molecules beyond PD-L1 that are amenable to therapeutic targeting.

METHODS

We analyzed RNA-sequencing data from SCLC cell lines (n = 108) and primary tumor specimens (n = 81) for expression of 39 functionally validated inhibitory checkpoint ligands. Furthermore, we generated tissue microarrays containing SCLC cell lines and patient with SCLC specimens to confirm expression of these molecules by immunohistochemistry. We annotated patient outcomes data, including treatment response and overall survival.

RESULTS

The checkpoint protein B7-H6 (NCR3LG1) exhibited increased protein expression relative to PD-L1 in cell lines and tumors (p < 0.05). Higher B7-H6 protein expression correlated with longer progression-free survival (p = 0.0368) and increased total immune infiltrates (CD45+) in patients. Furthermore, increased B7-H6 gene expression in SCLC tumors correlated with a decreased activated natural killer cell gene signature, suggesting a complex interplay between B7-H6 expression and immune signature in SCLC.

CONCLUSIONS

We investigated 39 inhibitory checkpoint molecules in SCLC and found that B7-H6 is highly expressed and associated with progression-free survival. In addition, 26 of 39 immune checkpoint proteins in SCLC tumors were more abundantly expressed than PD-L1, indicating an urgent need to investigate additional checkpoint targets for therapy in addition to PD-L1.

Bromodomain protein BRD4 is an epigenetic activator of B7-H6 expression in acute myeloid leukemia

B7-H6, a ligand for the NK activating receptor NKp30, has been identified as a biomarker of poor prognosis in several solid cancers. However, little is known about the role of B7-H6 and the mechanisms that control its expression in acute myeloid leukemia (AML). Epigenome modulation, including epigenomic reader dysregulation, is one of the hallmarks of AML. Bromodomain-containing protein 4 (BRD4), the best-known member of the BET family of epigenetic readers, is overexpressed in AML cells and regulates the transcription of genes involved in the pathogenesis of AML, as MYC oncogene. Here, we analyze the role of BRD4 in regulating B7-H6 in AML cells. Results demonstrated that the specific inhibition of BRD4 drastically reduces the expression of B7-H6 in AML cells. Histone acetylation mediated by CBP30/P300 facilitates the binding of BRD4 to the B7-H6 promoter, which recruits the P-TEFb elongation factor that phosphorylates RNA polymerase II, thereby activating B7-H6 transcription. BRD4 also co-bounded with JMJD6 at the distal enhancer of the B7-H6 gene. Metabolic modulation with metformin modifies the acetylation pattern in the B7-H6 promoter, impairing BRD4 binding, thereby inhibiting B7-H6 expression. B7-H6 knockdown induces the apoptosis in HEL-R cell line. Moreover, a high level of B7-H6 expression in AML patients is related to increased BRD4 levels, myelodysplastic-derived AML, and del5q, the two latter being associated with poor prognosis. Our data show that BRD4 is a positive regulator of the pro-tumorigenic molecule B7-H6 and that the blockage of the B7-H6 is a potential therapeutic target for the treatment of AML.

B7-H6, an immunoligand for the natural killer cell activating receptor NKp30, reveals inhibitory effects on cell proliferation and migration, but not apoptosis, in cervical cancer derived-cell lines

Background

Although great progress has been made in treatment regimens, cervical cancer remains as one of the most common cancer in women worldwide. Studies focusing on molecules that regulate carcinogenesis may provide potential therapeutic strategies for cervical cancer. B7-H6, an activating immunoligand expressed by several tumor cells, is known to activate NK cell-mediated cytotoxicity once engaged with its natural receptor NKp30. However, the opposite, that is, the effects in the tumor cell triggered by B7-H6 after interacting with NKp30 has not yet been well explored.

Methods

In this study, we evaluated the surface expression of B7-H6 by flow cytometry. Later, we stimulated B7-H6 positive cervical cancer derived-cell lines (HeLa and SiHa) with recombinant soluble NKp30 (sNKp30) protein and evaluated biological effects using the impedance RTCA system for cell proliferation, the scratch method for cell migration, and flow cytometry for apoptosis. Cellular localization of B7-H6 was determined using confocal microscopy.

Results

Notably, we observed that the addition of sNKp30 to the cervical cancer cell lines decreased tumor cell proliferation and migration rate, but had no effect on apoptosis. We also found that B7-H6 is selectively maintained in tumor cell lines, and that efforts to sort and purify B7-H6 negative or positive cells were futile, as negative cells, when cultured, regained the expression of B7-H6 and B7-H6 positive cells, when sorted and cultivated, lost a percentage of B7-H6 expression.

Conclusions

Our results suggest that B7-H6 has an important, as of yet undescribed, role in the biology of the cervical tumor cells themselves, suggesting that this protein might be a promising target for anti-tumor therapy in the future.

Positive staining of the immunoligand B7-H6 in abnormal/transformed keratinocytes consistently accompanies the progression of cervical cancer

Background

B7-H6 has been revealed as an endogenous immunoligand expressed in a variety of tumors, but not expressed in healthy tissues. Heretofore, no studies have been reported describing B7-H6 in women with cervical cancer. To investigate this question, our present study was conducted.

Results

This retrospective study comprised a total of 62 paraffinized cervical biopsies, which were distributed in five groups: low-grade squamous intraepithelial lesions (LSIL), high-grade squamous intraepithelial lesions (HSIL), squamous cervical carcinoma (SCC), uterine cervical adenocarcinoma (UCAC), and a group of cervicitis (as a control for non-abnormal/non-transformed cells). Cervical sections were stained by immunohistochemistry to explore the expression of B7-H6, which was reported according to the immunoreactive score (IRS) system. We observed a complete lack of B7-H6 in LSIL abnormal epithelial cells. Interestingly, B7-H6 began to be seen in HSIL abnormal epithelial cells; more than half of this group had B7-H6 positive cells, with staining characterized by a cytoplasmic and membranous pattern. B7-H6 in the SCC group was also seen in the majority of the sections, showing the same cytoplasmic and membranous pattern. Strong evidence of B7-H6 was notably found in UCAC tumor columnar cells (in 100% of the specimens, also with cytoplasmic and membranous pattern). Moreover, consistent B7-H6 staining was observed in infiltrating plasma cells in all groups.

Conclusions

B7-H6 IRS positively correlated with disease stage in the development of cervical cancer; additionally, B7-H6 scores were found to be even higher in the more aggressive uterine cervical adenocarcinoma, suggesting a possible future therapeutic target for this cancer type.

Cytisine-Pterocarpan-Derived Compounds: Biomimetic Synthesis and Apoptosis-Inducing Activity in Human Breast Cancer Cells

Cytisine-pterocarpan derived compounds were biomimetically synthesized with (-)-cytisine and (-)-maackiain via a N,N-4-dimethyl-4-aminopyridine (DMAP)-mediated synthetic strategy in a mild manner. In the present study, tonkinensine B (4) was elaborated in good and high yields with the optimized reaction conditions. The in vitro cytotoxicity of compound 4 was evaluated against breast cancer cell lines and showed that 4 had a better cytotoxicity against MDA-MB-231 cells (IC₅₀ = 19.2 μM). Depending on the research on cytotoxicities of 4 against RAW 264.7 and BV2 cells, it was suggested that 4 produced low cytotoxic effects on the central nervous system. Further study indicated that 4 demonstrated cytotoxic activity against MDA-MB-231 cells and the cytotoxic activity was induced by apoptosis. The results implied that the apoptosis might be induced by mitochondrion-mediated apoptosis via regulating the ratio of Bax/Bcl-2 and promoting the release of cytochrome c from the mitochondrion to the cytoplasm in MDA-MB-231 cells.