BERKELEY, CA (UroToday.com) - In prostate cancer, the first line of treatment is adopted by causing androgen deprivation to cancer cells, which are initially dependent on androgen for rapid proliferation and growth. But the cancer cells soon become resistant to this therapy as they become independent of androgen for growth. So the current targeted therapeutic approach against this fatal disease has been shifted to a pharmacological inhibition of 5-LOX, the enzyme responsible for de-oxygenation of arachidonic acid (a common omega-6poly-unsaturated fatty acid). This enzymatic reaction produces 5-HETE and leukotriene, which principally get activated by binding with OXER1 to induce uncontrolled proliferation in cancer cells. Lycopodium extract is used as a medication against enlarged prostate in homeopathy. The bioactive component of this crude extract, namely lycopodine, had earlier been shown to have a remarkable anti-cancer effect against HeLa cervix cancer cell in our laboratory.
In continuation to that, the present study was designed to evaluate the efficacy of lycopodine against prostate cancer of both androgen dependent (LnCaP) and independent (PC3) cell types, along with understanding its molecular mechanism of action. Lycopodine decreased viability of prostate cancer cells by bringing down OXER1 activity. Further, when 5-LOX activity was checked in presence and absence of arachidonic acid, it was revealed that lycopodine could down-regulate/block the activity of 5-LOX in presence of its substrate. Thus, this drug could down-regulate LOX action in fatty acid metabolism, irrespective of whether there was androgen dependency or independency of the cancer cells, rendering advantage in an effective drug design for prostate cancer or any other disease where 5-LOX activity is reported to play a central role.
In fact, 5-LOX is known to play a dynamic role in many metabolic disorders. If the activity of this gene could be blocked or silenced, further cell cycle would get arrested. In this study, reduction in EGF expression with cell cycle arrest at G0/G1 stage was a clear indication of reduction in proliferation with an up-regulated p21 activity. The increase in the activity of p21 supports action of the drug in hindering the cellular growth and cell cycle blockage. So the interactive potential of the drug with cellular DNA was checked by CD spectroscopy. CD data revealed the ability of lycopodine to intercalate with calf thymus DNA and drug-treated cellular DNA. So another way lycopodine could inhibit cell proliferation might be through its interference with the replication process of DNA and production of cytotoxic hindrances that also could have z serious effect on the normal process of DNA synthesis and transcription. This blocking capacity of lycopodine in DNA synthesis has tremendous implication in anti-cancer DNA-targeted drug designing. p53 also plays a central regulatory role in the process of apoptosis. p53 gene gets mutated in some types of cancers and becomes incompatible for inducing apoptosis. In this experiment, therefore, two types of cell lines have been chosen, of which PC3 is p53 mutated and LnCaP is p53 non-mutated. Results suggested that lycopodine had the capability to induce apoptosis through mitochondrial membrane depolarization, without the involvement of p53.
In conclusion, our present study suggests that lycopodine can intercalate well with the cellular DNA and thus inhibit proliferation and induce type-1 apoptosis in human prostate cancer cells. Concrete evidences of its possible mechanism and pathways of action in causing death to both hormone-sensitive and -refractory prostate carcinoma cells have been provided. The mechanism involved seems to be mediated through down-regulating 5-lipoxygenase activity, disruption of the mitochondrial membrane potential without involvement of p53, modulating mitochondrial pro- and anti-apoptotic proteins, and activation of caspase-3 in a sequential manner.
Written by:
Kausik Bishayee as part of Beyond the Abstract on UroToday.com. This initiative offers a method of publishing for the professional urology community. Authors are given an opportunity to expand on the circumstances, limitations etc... of their research by referencing the published abstract.
Cytogenetics and Molecular Biology Laboratory, Department of Zoology, University of Kalyani, Kalyani 741235, India
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