title: Differential expression of a novel voltage gated potassium channel--Kv 1.5 in astrocytomas and its impact on prognosis in glioblastoma.
abstract: BACKGROUND
  Ion channels are subjects of intense research, due to their easy access and potential for being drug targets. Kv1.5 is a voltage gated potassium channel, earlier thought to be cardiac specific. Recent studies have revealed that K(+) channels play an important role in apoptosis, glial cell proliferation and biology of various cancers. No study has so far been performed to assess their expression in astrocytomas and correlate its impact on the clinical behaviour of gliomas.
  
  
  METHODS
  Sixty samples of astrocytoma which included 9 diffuse astrocytoma (DA) grade II, 11 anaplastic astrocytoma (AA) grade III and 40 glioblastoma (GBM), along with normal brain tissue (cerebral cortex; n = 5) were analysed for their Kv1.5 protein expression. Immunohistochemical expression of Kv1.5 in various grades was assessed semi quantitatively. The patients with GBM (n = 40) were treated with uniform protocol and their survival was documented.
  
  
  RESULTS
  The mean expression of Kv1.5 in DA, AA and GBM was 22.2 ± 9.71%, 11.81 ± 12.3% and 10.37 ± 11.05%, respectively, the difference being statistically significant (p = 0.004). The mean expression in low grade astrocytoma (WHO II) was significantly higher than higher grades (22.2% and 10.7%; p = 0.005). On analysing the influence of Kv1.5 expression on survival of GBM patients, we noted that increasing Kv1.5 labelling index (LI) correlated with a favourable prognosis, albeit not being significant (p = 0.310; HR = 0.901).
  
  
  CONCLUSIONS
  Kv1.5 expression occurs more in DA, when compared to high grade astrocytoma. GBM patients with higher Kv1.5 expression had better survival, though not reaching statistical significance.
authors.affiliation: Department of Neurosurgery, National Institute of Mental Health and Neurosciences, Bangalore, India.
authors.forename: S
authors.initials: S
authors.lastname: Arvind
authors.forename: A
authors.initials: A
authors.lastname: Arivazhagan
authors.forename: V
authors.initials: V
authors.lastname: Santosh
authors.forename: B A
authors.initials: BA
authors.lastname: Chandramouli
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D001254:Astrocytoma / Q000378:metabolism* / Q000628:therapy; D001932:Brain Neoplasms / Q000378:metabolism* / Q000628:therapy; D003131:Combined Modality Therapy; D005500:Follow-Up Studies; D005909:Glioblastoma / Q000378:metabolism* / Q000628:therapy; D006801:Humans; D007150:Immunohistochemistry; D051666:Kv1.5 Potassium Channel / Q000378:metabolism*; D008875:Middle Aged; D016019:Survival Analysis; D016896:Treatment Outcome; D055815:Young Adult
chemical_list: D051666:Kv1.5 Potassium Channel