Junaid Abdulghani

Stat3 promotes metastatic progression of prostate cancer.

There are currently no effective therapies for metastatic prostate cancer because the molecular mechanisms that underlie the metastatic spread of primary prostate cancer are unclear. Transcription factor Stat3 is constitutively active in malignant prostate epithelium, and its activation is associated with high histological grade and advanced cancer stage. In this work, we hypothesized that Stat3 stimulates metastatic progression of prostate cancer. We show that Stat3 is active in 77% of lymph node and 67% of bone metastases of clinical human prostate cancers. Importantly, adenoviral gene delivery of wild-type Stat3 (AdWTStat3) to DU145 human prostate cancer cells increased the number of lung metastases by 33-fold in an experimental metastasis assay compared with controls. Using various methods to inhibit Stat3, we demonstrated that Stat3 promotes human prostate cancer cell migration. Stat3 induced the formation of lamellipodia in both DU145 and PC-3 cells, further supporting the concept that Stat3 promotes a migratory phenotype of human prostate cancer cells. Moreover, Stat3 caused the rearrangement of cytoplasmic actin stress fibers and microtubules in both DU145 and PC-3 cells. Finally, inhibition of the Jak2 tyrosine kinase decreased both activation of Stat3 and prostate cancer cell motility. Collectively, these data indicate that transcription factor Stat3 is involved in metastatic behavior of human prostate cancer cells and may provide a therapeutic target to prevent metastatic spread of primary prostate cancer.

TRAIL receptor signaling and therapeutics

Importance of the field: TNF-related apoptosis-inducing ligand (TRAIL) is a member of the TNF family of cytokines, which can induce apoptotic cell death in a variety of tumor cells by engaging specific death receptors, TRAIL-R1 and TRAIL-R2, while having low toxicity towards normal cells. There is interest in cancer therapy inducing cell death by activation of the death-receptor-mediated apoptotic pathway while avoiding decoy-receptor-mediated neutralization of the signal. This has led to the development of a number of receptor-specific TRAIL-variants and agonistic antibodies. Some of these soluble recombinant TRAIL and agonist antibodies targeting TRAIL-R1 and/or TRAIL-R2 are progressing in clinical trials. In addition, TRAIL-resistant tumors can be sensitized to TRAIL by a combination of TRAIL or agonistic antibodies with chemotherapeutic agents, targeted small molecules or irradiation. Areas covered in this review: Recent advances in developing TRAIL or its agonist receptor antibodies in cancer therapy. We also discuss combination therapies in overcoming TRAIL resistance in cancer cells. What the reader will gain: Knowledge of current clinical trials, the promise and obstacles in the future development of therapies affecting TRAIL signaling pathways. Take home message: Cancer therapeutics targeting the TRAIL/TRAIL receptor signaling pathway hold great promise for molecularly targeted pro-apoptotic anti-cancer therapy.

Transcription Factor Stat5 Synergizes with Androgen Receptor in Prostate Cancer Cells

The molecular mechanisms underlying progression of prostate cancer to the hormone-independent state are poorly understood. Signal transducer and activator of transcription 5a and 5b (Stat5a/b) is critical for the viability of human prostate cancer cells. We have previously shown that Stat5a/b is constitutively active in high-grade human prostate cancer, but not in normal prostate epithelium. Furthermore, activation of Stat5a/b in primary human prostate cancer predicted early disease recurrence. We show here that transcription factor Stat5a/b is active in 95% of clinical hormone-refractory human prostate cancers. We show for the first time that Stat5a/b synergizes with androgen receptor (AR) in prostate cancer cells. Specifically, active Stat5a/b increases transcriptional activity of AR, and AR, in turn, increases transcriptional activity of Stat5a/b. Liganded AR and active Stat5a/b physically interact in prostate cancer cells and, importantly, enhance nuclear localization of each other. The work presented here provides the first evidence of synergy between AR and the prolactin signaling protein Stat5a/b in human prostate cancer cells.

Quinacrine sensitizes hepatocellular carcinoma cells to TRAIL and chemotherapeutic agents.

Quinacrine has been widely explored in treatment of malaria, giardiasis, and rheumatic diseases. We find that quinacrine stabilizes p53 and induces p53-dependent and independent cell death. Treatment by quinacrine alone at concentrations of 10–20 mM for 1–2 d cannot kill hepatocellular carcinoma cells, such as HepG2, Hep3B, Huh7, which are also resistant to TRAIL. However, quinacrine renders these cells sensitive to treatment by TRAIL. Co-treatment of these cells with quinacrine and TRAIL induces overwhelming cell death within 3–4 h. Levels of DR5, a pro-apoptotic death receptor of TRAIL, are increased upon treatment with quinacrine, while levels of Mcl-1, an anti-apoptotic member of the Bcl-2 family, are decreased. While the synergistic effect of quinacrine with TRAIL appears to be in part independent of p53, knockdown of p53 in HepG2 cells by siRNA results in more cell death after treatment by quinacrine and TRAIL. The mechanism by which quinacrine sensitizes hepatocellular carcinoma cells to TRAIL and chemotherapies, and the potential for clinical application currently are being further explored. Lastly, quinacrine synergizes with chemotherapeutics, such as adriamycin, 5-FU, etoposide, CPT11, sorafenib, and gemcitabine, in killing hepatocellular carcinoma cells in vitro and the drug enhances the activity of sorafenib to delay tumor growth in vivo.

Sorafenib Sensitizes Solid Tumors to Apo2L/TRAIL and Apo2L/TRAIL Receptor Agonist Antibodies by the Jak2-Stat3-Mcl1 Axis

Background Approximately half of tumor cell lines are resistant to the tumor-selective apoptotic effects of tumor necrosis factor-related apoptosis-inducing ligand (Apo22L/TRAIL). Previously, we showed that combining Apo2L/TRAIL with sorafenib, a multikinase inhibitor, results in dramatic efficacy in Apo2L/TRAIL-resistant tumor xenografts via inhibition of Mcl-1. Soluble Apo2L/TRAIL is capable of binding to several surface receptors, including the pro-apoptotic death receptors, DR4 and DR5, and decoy receptors, DcR1 and DcR2. Monoclonal antibodies targeting either of these death receptors are being investigated as antitumor agents in clinical trials. We hypothesized that sorafenib and Apo2L/TRAIL or Apo2L/TRAIL death receptor agonist (TRA) antibodies against DR4 (mapatumumab) and DR5 (lexatumumab) will overcome resistance to Apo2L/TRAIL-mediated apoptosis and as increase antitumor efficacy in Apo2L/TRAIL-sensitive solid tumors. Methodology/Principal Findings We found that Apo2L/TRAIL or TRA antibodies combined with sorafenib synergistically reduce cell growth and increase cell death across a panel of solid tumor cell lines in vitro. This panel included human breast, prostate, colon, liver and thyroid cancers. The cooperativity of these combinations was also observed in vivo, as measured by tumor volume and TUNEL staining as a measure of apoptosis. We found that sorafenib inhibits Jak/Stat3 signaling and downregulates their target genes, including cyclin D1, cyclin D2 and Mcl-1, in a dose-dependent manner. Conclusions/Significance The combination of sorafenib with Apo2L/TRAIL or Apo2L/TRAIL receptor agonist antibodies sensitizes Apo2L/TRAIL-resistant cells and increases the sensitivity of Apo2L/TRAIL-sensitive cells. Our findings demonstrate the involvement of the Jak2-Stat3-Mcl1 axis in response to sorafenib treatment, which may play a key role in sorafenib-mediated sensitization to Apo2L/TRAIL.

Nuclear Stat5a/b predicts early recurrence and prostate cancer-specific death in patients treated by radical prostatectomy.

There is an urgent need for reliable markers to identify patients whose prostate cancer (PCa) will recur after initial therapy and progress to lethal disease. Gleason score (GS) is considered the most accurate predictive marker for disease-specific mortality after primary treatment of localized PCa. Most PCas cluster into groups of GS 6 and 7 with considerable variation in the disease recurrence and disease-specific death. In preclinical PCa models, Stat5a/b promotes PCa growth and progression. Stat5a/b is critical for PCa cell viability in vitro and for tumor growth in vivo and promotes metastatic dissemination of cancer in nude mice. Here, we analyzed the predictive value of high nuclear Stat5a/b protein levels in 2 cohorts of PCas: Material I (n = 562) PCas treated by radical prostatectomy (RP), and Material II (n = 106) PCas treated by deferred palliative therapy. In intermediate GS PCas treated by radical prostatectomy, high levels of nuclear Stat5a/b predicted both early recurrence (univariable analysis; P < .0001, multivariable analysis; HR = 1.82, P = .017) and early PCa-specific death (univariable analysis; P = .028). In addition, high nuclear Stat5a/b predicted early disease recurrence in both univariable (P < .0001) and multivariable (HR = 1.61; P = .012) analysis in the entire cohort of patients treated by RP regardless of the GS. Patients treated by deferred palliative therapy, elevated nuclear Stat5a/b expression was associated with early PCa-specific death by univariable Cox regression analysis (HR = 1.59; 95% CI = [1.04, 2.44]; P = .034). If confirmed in future prospective studies, nuclear Stat5a/b may become a useful independent predictive marker of recurrence of lethal PCa after RP for intermediate GS PCas.

Pharmacologic Suppression of JAK1/2 by JAK1/2 Inhibitor AZD1480 Potently Inhibits IL-6–Induced Experimental Prostate Cancer Metastases Formation

Metastatic prostate cancer is lethal and lacks effective strategies for prevention or treatment, requiring novel therapeutic approaches. Interleukin-6 (IL-6) is a cytokine that has been linked with prostate cancer pathogenesis by multiple studies. However, the direct functional roles of IL-6 in prostate cancer growth and progression have been unclear. In the present study, we show that IL-6 is produced in distant metastases of clinical prostate cancers. IL-6–activated signaling pathways in prostate cancer cells induced a robust 7-fold increase in metastases formation in nude mice. We further show that IL-6 promoted migratory prostate cancer cell phenotype, including increased prostate cancer cell migration, microtubule reorganization, and heterotypic adhesion of prostate cancer cells to endothelial cells. IL-6–driven metastasis was predominantly mediated by Stat3 and to lesser extent by ERK1/2. Most importantly, pharmacologic inhibition of Jak1/2 by AZD1480 suppressed IL-6–induced signaling, migratory prostate cancer cell phenotypes, and metastatic dissemination of prostate cancer in vivo in nude mice. In conclusion, we demonstrate that the cytokine IL-6 directly promotes prostate cancer metastasis in vitro and in vivo via Jak–Stat3 signaling pathway, and that IL-6–driven metastasis can be effectively suppressed by pharmacologic targeting of Jak1/2 using Jak1/2 inhibitor AZD1480. Our results therefore provide a strong rationale for further development of Jak1/2 inhibitors as therapy for metastatic prostate cancer. Mol Cancer Ther; 13(5); 1246–58. ©2014 AACR.

Sorafenib and Quinacrine Target Anti-Apoptotic Protein MCL1: A Poor Prognostic Marker in Anaplastic Thyroid Cancer (ATC).

Purpose and Experimental Design: Anaplastic thyroid cancer (ATC) comprises approximately 2% of all thyroid cancers, and its median survival rate remains poor. It is responsible for more than one third of thyroid cancer–related deaths. ATC is frequently resistant to conventional therapy, and NFκB signaling has been proposed to be a feature of the disease. We aimed to assess the activity of the antimalaria drug quinacrine known to target NFκB signaling in combination with the clinically relevant kinase inhibitor sorafenib in ATC cells. The presence of NFκB-p65/RELA and its target MCL1 was demonstrated in ATC by meta-data gene set enrichment analysis and IHC. We assessed the responses of a panel of human ATC cell lines to quinacrine and sorafenib in vitro and in vivo. Results: We detected increased expression of NFκB-p65/RELA and MCL1 in the nucleus of a subset of ATC compared with non-neoplastic thyroid. ATC cells were found to respond with additive/synergistic tumor cell killing to the combination of sorafenib plus quinacrine in vitro, and the drug combination improves survival of immunodeficient mice injected orthotopically with ATC cells as compared with mice administered either compound alone or doxorubicin. We also demonstrate that the combination of sorafenib and quinacrine is well tolerated in mice. At the molecular level, quinacrine and sorafenib inhibited expression of prosurvival MCL1, pSTAT3, and dampened NFκB signaling. Conclusions: The combination of quinacrine and sorafenib targets emerging molecular hallmarks of ATC and shows promising results in clinically relevant models for the disease. Further testing of sorafenib plus quinacrine can be conducted in ATC patients. Clin Cancer Res; 22(24); 6192–203. ©2016 AACR.

Molecular and Genetic Markers of Follicular-Cell Thyroid Cancer: Etiology and Diagnostic and Therapeutic Opportunities

Thyroid cancer has an increasing incidence in the US population and worldwide, with 95% of the cancers being of follicular cell origin-papillary, follicular, or anaplastic thyroid carcinomas. Both follicular and papillary thyroid cancers portend good survival rates, with estimated 5-year survival amongst differentiated thyroid cancer approaching 97%. On the other hand, the median survival for a patient with anaplastic thyroid carcinoma is measured in months. Despite the optimistic survival rates for papillary and follicular thyroid carcinoma, a subset of this population demonstrates resistance to radioactive iodine, and a proclivity for more aggressive tumors with higher rates of recurrence and metastasis.As there is an increased understanding of the molecular etiology of thyroid cancer, there is also a new interest in alternative treatment methods for those nonresponsive to typical treatment. Multiple signaling pathways have been identified, including the mitogen activated protein kinase pathway, as crucial to thyroid tumor formation and progression. Additionally, particular oncogenes have been identified as prevalent in anaplastic thyroid carcinoma and thought to be involved in the transformation from differentiated to anaplastic histology.We review the current literature and evidence describing the molecular and genetic etiology of non-medullary (follicular cell derived) thyroid carcinomas including papillary, follicular, and anaplastic thyroid carcinoma. Additionally, we evaluate the current literature on emerging and established therapies of molecular and genetic targets in these cancers.

Impact of Genetic Targets on Prostate Cancer Therapy

Given the global incidence of prostate cancer and its sociological impact, it remains a challenging disease to clinicians and researchers alike. In the last few years several new drugs have been added to the armamentarium of prostate cancer therapy and offers survival benefit to patients with prostate cancer. However, effective drugs are still needed that offer extended survival benefit and alter the natural history of the disease. Recent efforts have focused on better understanding the underlying biology and genetic heterogeneity of the disease and identified novel targets that can be utilized for drug development and therapeutics in the future. In this review we present an overview of the genetic landscape of prostate cancer, novel targets in the prostate cancer therapy and the results of key clinical trials of these novel drugs.