Current study was done to assess possible anti-proliferative effect of nanomicelle curcumin (NMCM) against germ cells in testicular tissue. For this purpose, 24 mature male Wistar rats were divided into control and test groups. The animals in test groups received 7.5 mg/kg, 15 mg/kg and 30 mg/kg of NMC (NO = 6 rats in each group). Following 48 days, the expression of Bcl-2, Bax, caspase-3, P53 and proliferating cell nuclear antigen (PCNA) were evaluated by using reverse transcription-PCR and immunohistochemistry. Histological changes, tubular differentiation index (TDI), tissue cellularity and serum level of testosterone were analyzed. Finally, the DNA laddering test was used to assess the DNA fragmentation as hallmark for apoptosis. The NMCM significantly (P < 0.05) diminished the Bcl-2, p53 and PCNA and enhanced the Bax and caspase-3 mRNA levels. The NMCM significantly (P < 0.05) elevated the percentage of Bax and caspase-3-positive tubules and remarkably reduced the percentage of tubules with positive reaction for Bcl-2, p53 and PCNA. The NCMN-received animals exhibited remarkable (P < 0.05) reduction in cell population, TDI ratio and serum level of testosterone. Severe DNA fragmentation was observed in 30 mg/kg NMCM-received group. In conclusion, the NMCM by reducing the testicular endocrine status, down-regulating Bcl-2 expression and by enhancing the Bax and caspase-3 expression initiates the intrinsic apoptosis pathway. On the other hand, inhibited expression of p53 and PCNA (at dose level of 30 mg/kg) suppresses the p53 and PCNA-related hemostasis/preservative reactions. All these alterations adversely affect the spermatogenesis.
Curcumin (CMN), primary ingredient of Tumeric (Curcuma Longa), has been known as the main part of Indians condiment (Choudhary and Sekhon, 2012). Multiple therapeutic properties of the CMN are well established in several investigations. Accordingly, anti-inflammatory, antioxidant and anticancer effects have been reported for CMN-related remedial traits (Malani and Ichikawa, 2007). Among several characteristics of CMN, its anti-proliferative impact on carcinogenic cells has attracted a lot of attentions. Earlier study by Mehta et al. (1997) showed that, the CMN results in cell cycle arrest at G2/S phase in breast tumor cell lines in vitro (Mehta et al., 1997).More recent studies have shown the CMN-induced anti-proliferative/anti-growth impacts at other stages as G2/M in breast tumor cells (Kumaravel et al., 2012) as well as G0/G1 stages in pancreatic stellate cells (Gundewar et al., 2015). More characteristics including; inhibiting ornithine decarboxylase activity (Mehta et al., 1997), downregulating p21WAF1/Cip1 expression (Gundewar et al., 2015) and diminishing of cyclin D1, cyclin E, cyclin A, cyclin-dependent kinase 2 (CDK2) and CDK4 expression as well as inducing cell cycle inhibitor p21 and p27 expression are reported, representing the anti-proliferative effect of CMN (Kumaravel et al., 2012; Zhou et al., 2011). Aside the anti-proliferative impacts, the CMN has been known as pro-apoptotic agent in various studies. Accordingly, the CMN by activating the JNK/ERK (Yang et al., 2012), p38 mitogenactivated protein kinase (Hu et al., 2005), miR-192-5p/215 induction and the p53-miR-192-5p/215-XIAP pathways (Ye et al., 2015) stimulates or initiates apoptosis in different cell lines. Moreover, last researches have shown the involvement of CMN in p53-dependent apoptosis pathways (Keshavarz et al., 2016; Li et al., 2015). In another study, Cao et al. (2006), have illustrated the impressive effect of CMN on mitochondrial and nuclear DNA integrity by illustrating impressive DNA damage in human hepatoma G2 cells (Cao et al., 2006).