BACKGROUND:The objective of this study was to document the differences in testosterone (T) levels between crizotinib-treated and noncrizotinib-treated patients with metastatic nonsmall cell lung cancer (NSCLC). METHODS: Testosterone levels were measured in 19 men with metastatic NSCLC who received crizotinib and in 19 men with metastatic NSCLC who did not receive crizotinib. Clinical characteristics of the patients were compared, and additional hormone assays were performed as appropriate. Two patients who began crizotinib and 4 patients who had dose interruptions or who stopped crizotinib therapy had serial hormone measurements, permitting the documentation of dynamic hormone changes on and off crizotinib treatment. RESULTS: Total T levels were low (<241 ng/dL) in 19 of 19 (100%) crizotinib-treated men and in 6 of 19 men (32%) with metastatic NSCLC who did not receive crizotinib (mean T levels, 131 ng/dL and 311 ng/dL, respectively; P ¼ .0002). Only 1 in 5 patients who had anaplastic lymphoma kinase (ALK) gene rearrangements and had not yet received crizotinib had low T. The initiation of crizotinib in 2 patients who had previously normal T levels was associated with a rapid decreases in T and in luteinizing hormone and follicle stimulating hormone levels within 14 to 21 days. Discontinuation of crizotinib led to increases back to normal T levels. CONCLUSIONS: Crizotinib therapy caused rapid suppression of T levels in men. The current results indicated that the site of action must include a central (hypothalamic or pituitary) effect, but additional direct testicular effects could not be excluded. Further work is required to assess the correlation between low T levels and crizotinib side effects as well as the exact molecular mechanism and site of drug toxicity. Cancer 2012;118:5302-9. V C 2012American Cancer Society.KEYWORDS: crizotinib, nonsmall cell lung cancer, testosterone, anaplastic lymphoma kinase gene rearrangements, hypogonadism. INTRODUCTIONApproximately 4% of patients with nonsmall cell lung cancer (NSCLC) have rearrangements in the anaplastic lymphoma kinase (ALK) gene, leading to an oncogene-addicted state from aberrant ALK activation. 1-9 Crizotinib, an oral ALK and MET-directed tyrosine kinase inhibitor, has produced a high response rate and prolonged median progression-free survival in patients with ALK-positive NSCLC. 10 Side effects of crizotinib include grade 1/2 nausea (54%), diarrhea (48%), visual disturbance (41%), constipation (24%), dizziness (15%), and fatigue (10%). 10 Crizotinib (Xalkori; Pfizer, New York, NY) recently received US Food and Drug Administration approval for the treatment of patients with advanced, ALK-rearranged NSCLC, a group that potentially represents >10,000 patients per year in the United States alone. 11 The potential for crizotinib-related hypogonadism came to our attention through an index case. A man aged 35 years with metastatic NSCLC and an ALK rearrangement who received crizotinib (250 mg twice daily in 28-day cycles) for 14 cycles reported worsening fatigue...

The membrane tyrosine kinase receptors, AXL and MET, are implicated in GnRH neuron migration and/or survival. We hypothesized that the receptors with their ligands, GAS6 and HGF, respectively may cross-talk in GnRH neuronal function. In NLT GnRH neuronal cells, MET co-immunoprecipitated with AXL, although HGF or GAS6 did not transphosphorylate AXL or MET, respectively. Co-expression of a kinase dead AXL blocked HGF activation of MET and indirectly AKT and p38MAPK. Silencing of AXL decreased HGF’s ability to phosphorylate MET and activate AXL’s downstream effectors, p38MAPK and AKT. HGF/MET signaling modulated neuron migration dependent and independent of AXL co-expression and p38MAPK. Conversely, AXL’s control of GnRH neuronal survival was dependent on HGF/MET signaling. Together, these data support that the importance of membrane tyrosine kinase receptor crosstalk to regulate neuronal cell-specific developmental functions.

Functional consequences of AXL sequence variants in patients with idiopathic hypogonadotropic hypogonadism support the importance of AXL and the Tyro3, Axl, Mer (TAM) family in reproductive development.

Pituitary tumors of the gonadotrope lineage are often large and invasive, resulting in hypopituitarism. No medical treatments are currently available. Using a combined genetic and genomic screen of individual human gonadotrope pituitary tumor samples, we recently identified the mammalian sterile-20 like kinase 4 (MST4) as a protumorigenic effector, driving increased pituitary cell proliferation and survival in response to a hypoxic microenvironment. To identify novel inhibitors of the MST4 kinase for potential future clinical use, computational-based virtual library screening was used to dock the SelleckChem kinase inhibitor library into the ATP-binding site of the MST4 crystal structure. Several inhibitor candidates were identified with the potential to bind with high affinity. Using a TR-FRET in vitro recombinant kinase assay, hesperadin, initially described as an Aurora kinase inhibitor, exhibited potent inhibition of the MST4 kinase at nanomolar concentrations. The LβT2 gonadotrope pituitary cell hypoxic model was used to test the ability of this inhibitor to antagonize MST4 actions. Under short-term severe hypoxia (1% O2), MST4 protection from hypoxia-induced apoptosis was abrogated in the presence of hesperadin. Similarly, under chronic hypoxia (5%), hesperadin blocked the proliferative and colony-forming actions of MST4 as well as the ability to activate specific downstream signaling and hypoxia-inducible factor-1 effectors. Together, these data identify hesperadin as the first potent, selective inhibitor of the MST4 kinase with the capacity to block pituitary tumor cell growth in a hypoxic microenvironment.

Background: HDACs expression is increased in differentiated GnRH neuronal cells. Results: HDAC9/6 promotes GnRH neuronal cell survival and halts neuron movement. Conclusion: Class II HDACs can modulate GnRH neuronal functions. Significance: This study identifies a novel interaction of HDAC9 with HDAC6 in GnRH neuronal cells.