Abrogation of USP7 is an alternative strategy to downregulate PD-L1 and sensitize gastric cancer cells to T cells killing

Targeting immune checkpoints such as programmed cell death protein 1 (PD-1) and programmed death ligand-1 (PD-L1) have been approved for treating melanoma, gastric cancer (GC) and bladder cancer with clinical benefit. Nevertheless, many patients failed to respond to anti-PD-1/PD-L1 treatment, so it is necessary to seek an alternative strategy for traditional PD-1/PD-L1 targeting immunotherapy. Here with the data from The Cancer Genome Atlas (TCGA) and our in-house tissue library, PD-L1 expression was found to be positively correlated with the expression of ubiquitin-specific processing protease 7 (USP7) in GC. Furthermore, USP7 directly interacted with PD-L1 in order to stabilize it, while abrogation of USP7 attenuated PD-L1/PD-1 interaction and sensitized cancer cells to T cell killing in vitro and in vivo. Besides, USP7 inhibitor suppressed GC cells proliferation by stabilizing P53 in vitro and in vivo. Collectively, our findings indicate that in addition to inhibiting cancer cells proliferation, USP7 inhibitor can also downregulate PD-L1 expression to enhance anti-tumor immune response simultaneously. Hence, these data posit USP7 inhibitor as an anti-proliferation agent as well as a novel therapeutic agent in PD-L1/PD-1 blockade strategy that can promote the immune response of the tumor.

Enhanced immortalization, HUWE1 mutations and other biological drivers of breast invasive carcinoma in Black/African American patients

Black/African-American (B/AA) breast cancer patients tend to have more aggressive tumor biology compared to White/Caucasians. In this study, a variety of breast tumor molecular expression profiles of patients derived from the two racial groupings were investigated. Breast invasive carcinoma sample data (RNASeq version 2, Reverse Phase Protein Array, mutation, and miRSeq data) from the Cancer Genome Atlas were examined. The results affirm that B/AA patients are more likely than Caucasian patients to harbor the aggressive basal-like or the poor prognosis-associated HER2-enriched molecular subtypes of breast cancer. There is also a higher incidence of the triple-negative breast cancer (TNBC) among B/AA patients than the general population, a fact reflected in the mutation patterns of genes such as PIK3CA and TP53. Furthermore, an immortalization signature gene set, is enriched in samples from B/AA patients. Among stage III patients, TERT, DRAP1, and PQBP1, all members of the immortalization gene signature set, are among master-regulators with increased activity in B/AA patients. Master-regulators driving differences in expression profiles between the two groups include immortalization markers, senescence markers, and immune response and redox gene products. Differences in expression, between B/AA and Caucasian patients, of RB1, hsa-let-7a, E2F1, c-MYC, TERT, and other biomolecules appear to cooperate to enhance entry into the S-phase of the cell cycle in B/AA patients. Higher expression of miR-221, an oncomiR that facilitates entry into the cell cycle S-phase, is regulated by c-MYC, which is expressed more in breast cancer samples from B/AA patients. Furthermore, the cell migration- and invasion-promoting miRNA, miR-135b, has increased relative expression in B/AA patients. Knock down of the immortalization marker TERT inhibited triple-negative breast cancer cell lines (MDA-MB-231 and MDA-MB-468) cell viability and decreased expression of TERT, MYC and WNT11. For those patients with available survival data, prognosis of stage II patients 50 years of age or younger at diagnosis, was distinctly poorer in B/AA patients. Also associated with this subset of B/AA patients are missense mutations in HUWE1 and PTEN expression loss. Relative to Caucasian non-responders to endocrine therapy, B/AA non-responders show suppressed expression of a signature gene set on which biological processes including signaling by interleukins, circadian clock, regulation of lipid metabolism by PPARα, FOXO-mediated transcription, and regulation of TP53 degradation are over-represented. Thus, we identify molecular expression patterns suggesting diminished response to oxidative stress, changes in regulation of tumor suppressors/facilitators, and enhanced immortalization in B/AA patients are likely important in defining the more aggressive molecular tumor phenotype reported in B/AA patients.

Miltirone induces cell death in hepatocellular carcinoma cell through GSDME-dependent pyroptosis

Pyroptosis is a form of programmed cell death, and recently described as a new molecular mechanism of chemotherapy drugs in the treatment of tumors. Miltirone, a derivative of phenanthrene-quinone isolated from the root of Salvia miltiorrhiza Bunge, has been shown to possess anti-cancer activities. Here, we found that miltirone inhibited the cell viability of either HepG2 or Hepa1-6 cells, and induced the proteolytic cleavage of gasdermin E (GSDME) in each hepatocellular carcinoma (HCC) cell line, with concomitant cleavage of caspase 3. Knocking out GSDME switched miltirone-induced cell death from pyroptosis to apoptosis. Additionally, the induction effects of miltirone on GSDME-dependent pyroptosis were attenuated by siRNA-mediated caspase three silencing and the specific caspase three inhibitor Z-DEVD-FMK, respectively. Miltirone effectively elicited intracellular accumulation of reactive oxygen species (ROS), and suppressed phosphorylation of mitogen-activated and extracellular signal-regulated kinase (MEK) and extracellular regulated protein kinases 1/2 (ERK1/2) for pyroptosis induction. Moreover, miltirone significantly inhibited tumor growth and induced pyroptosis in the Hepa1-6 mouse HCC syngeneic model. These results provide a new insight that miltirone is a potential therapeutic agent for the treatment of HCC via GSDME-dependent pyroptosis.

Inactivation of TFEB and NF-κB by marchantin M alleviates the chemotherapy-driven pro-tumorigenic senescent secretion

It is critical to regulate the senescence-associated secretory phenotype (SASP) due to its effect on promoting malignant phenotypes and limiting the efficiency of cancer therapy. In this study, we demonstrated that marchantin M (Mar-M, a naturally occurring bisbibenzyl) suppressed pro-inflammatory SASP components which were elevated in chemotherapy-resistant cells. Mar-M treatment attenuated the pro-tumorigenic effects of SASP and enhanced survival in drug-resistant mouse models. No toxicity was detected on normal fibroblast cells or in animals following this treatment. Inactivation of transcription factor EB (TFEB) and nuclear factor-κB (NF-κB) by Mar-M significantly accounted for its suppression on the components of SASP. Furthermore, inhibition of SASP by Mar-M contributed to a synergistic effect during co-treatment with doxorubicin to lower toxicity and enhance antitumor efficacy. Thus, chemotherapy-driven pro-inflammatory activity, seen to contribute to drug-resistance, is an important target for Mar-M. By decreasing SASP, Mar-M may be a potential approach to overcome tumor malignancy.