Starving cancer cells to enhances DNA damage and immunotherapy response.

Prostate cancer (PCa) poses significant challenges in treatment, particularly when it progresses to a metastatic, castrate-resistant state. Conventional therapies, including chemotherapy, radiotherapy, and hormonal treatments, often fail due to toxicities, off-target effects, and acquired resistance. This research perspective defines an alternative therapeutic strategy focusing on the metabolic vulnerabilities of PCa cells, specifically their reliance on non-essential amino acids such as cysteine. Using an engineered enzyme cyst(e)inase to deplete the cysteine/cystine can induce oxidative stress and DNA damage in cancer cells. This depletion elevates reactive oxygen species (ROS) levels, disrupts glutathione synthesis, and enhances DNA damage, leading to cancer cell death. The combinatorial use of cyst(e)inase with agents targeting antioxidant defenses, such as thioredoxins, further amplifies ROS accumulation and cytotoxicity in PCa cells. Overall, in this perspective provides a compressive overview of the previous work on manipulating amino acid metabolism and redox balance modulate the efficacy of DNA repair-targeted and immune checkpoint blockade therapies in prostate cancer.

Codelivery of TGFß and Cox2 siRNA inhibits HCC by promoting T-cell penetration into the tumor and improves response to Immune Checkpoint Inhibitors.

Upregulation of TGFß and Cox2 in the tumor microenvironment results in blockade of T-cell penetration into the tumor. Without access to tumor antigens, the T-cell response will not benefit from administration of the immune checkpoint antibodies. We created an intravenous polypeptide nanoparticle that can deliver two siRNAs (silencing TGFß and Cox2). Systemic administration in mice, bearing a syngeneic orthotopic hepatocellular carcinoma (HCC), delivers the siRNAs to various cells in the liver, and significantly reduces the tumor. At 2 mg/kg (BIW) the nanoparticle demonstrated a single agent action and induced tumor growth inhibition to undetectable levels after five doses. Reducing the siRNAs to 1mg/kg BIW demonstrated greater inhibition in the presence of PD-L1 mAbs. After only three doses BIW, we could still recover a smaller tumor and, in tumor sections, showed an increase in penetration of CD4+ and CD8+ T-cells deeper into the remaining tumor that was not evident in animals treated with non-silencing siRNA. The combination of TGFß and Cox2 siRNA co-administered in a polypeptide nanoparticle can act as a novel therapeutic alone against HCC and may augment the activity of the immune checkpoint antibodies. Silencing TGFß and Cox2 converts an immune excluded (cold) tumor into a T-cell inflamed (hot) tumor.

The SH2 domain and kinase activity of JAK2 target JAK2 to centrosome and regulate cell growth and centrosome amplification.

JAK2 is cytokine-activated non-receptor tyrosine kinase. Although JAK2 is mainly localized at the plasma membrane, it is also present on the centrosome. In this study, we demonstrated that JAK2 localization to the centrosome depends on the SH2 domain and intact kinase activity. We created JAK2 mutants deficient in centrosomal localization ΔSH2, K882E and (ΔSH2, K882E). We showed that JAK2 WT clone strongly enhances cell proliferation as compared to control cells while JAK2 clones ΔSH2, K882E and (ΔSH2, K882E) proliferate slower than JAK2 WT cells. These mutant clones also progress much slower through the cell cycle as compared to JAK2 WT clone and the enhanced proliferation of JAK2 WT cells is accompanied by increased S -> G2 progression. Both the SH2 domain and the kinase activity of JAK2 play a role in prolactin-dependent activation of JAK2 substrate STAT5. We showed that JAK2 is an important regulator of centrosome function as the SH2 domain of JAK2 regulates centrosome amplification. The cells overexpressing ΔSH2 and (ΔSH2, K-E) JAK2 have almost three-fold the amplified centrosomes of WT cells. In contrast, the kinase activity of JAK2 is dispensable for centrosome amplification. Our observations provide novel insight into the role of SH2 domain and kinase activity of JAK2 in centrosome localization of JAK2 and in the regulation of cell growth and centrosome biogenesis.

Overexpression of microRNA-30a inhibits hepatitis B virus X protein-induced autophagosome formation in hepatic cells.

Hepatitis B virus (HBV) enters the host and survives by using several mechanisms. One of the ways that HBV survives and replicates in the host cells is by inducing autophagy. Previous reports have shown that microRNA (miRNA)-30a inhibits autophagosome formation in cancer cells. Hence, we hypothesized that overexpression of miRNA-30a could inhibit HBV-induced autophagosome formation in hepatic cells. To study this, both HepG2 cells and HepG2.2.1.5 cells (HBV-expressing stable cell line) were transfected with miRNA-30a, and the cells were collected either for RNA isolation or protein isolation after 72 h of transfection. Beclin-1 expression was significantly higher in untransfected HepG2.2.1.5 cells than in HepG2 cells. Western blots showed that miRNA-30a overexpression resulted in a significant decrease in beclin-1 expression (eight-fold and four-fold in HepG2 and HepG2.2.1.5 cells, respectively) and c-myc expression, whereas the numbers of terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL)-positive cells were increased. In contrast, overexpression of HBV X protein (HBx) in HepG2 cells resulted in the enhancement of beclin-1 (six-fold increase as compared with the empty vector-transfected cells) and c-myc expression, whereas the numbers of TUNEL-positive cells were reduced. To confirm these findings, HBx and miRNA-30a were coexpressed in HepG2 cells, and the results showed significant inhibition of autophagosome formation and beclin-1 and c-myc expression, whereas apoptosis increased. These data demonstrate that HBx induces autophagosome formation via beclin-1 expression, whereas miRNA-30a overexpression could successfully inhibit the beclin-1 expression induced by HBx, thereby modulating autophagosome formation in hepatic cells.