Biology Reference
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From the Table 4.14 , we see that the number of chloroplast small subsequences,
we are calling chloromiRs, in the noncoding chloroplast genome of a C 4 plant, the
sorghum (Sorghum bicolor, for a total length of 15,852 bases) susceptible to
hybridize the chloroplast tRNAs inside the chloroplast matrix is highly significantly
less than the same number observed in a C 3 plant, the wheat (Triticum æstivum, for
a total length of 16014 bases).
A classical normal test of equality between empirical means shows that the
number of the C 4 plant chloromiRs is significantly (with a threshold of 10 3 ) less
than that of the C 3 plant. The diminution of possibility of inhibition of the tRNA
transcription inside the chloroplast of the sorghum can participate to the better
efficacy of the cell diurnal respiration in this C 4 plant with respect to the less
efficient C 3 plant, the wheat.
4.5.2 Pathological Role in Cancer
For example, we can notice in patients with melanoma the presence of microRNAs
like miR-221 reducing the isomerase activity in melanoma cells (Segura
et al. 2012 ), hence increasing the high glycolysis rate [and favoring the pentose
phosphate pathway and the Warburg effect (Tennant et al. 2010 ; Diaz-Ruiz et al.
2011 ; Demetrius and Simon 2012 ; Davies et al. 2012 )] as well as the proliferative
growth rate of the melanoma cells by targeting c-kit, p27 and p57, and in the
patients with prostate cancer the presence of microRNAs like miR-34a, repressing
the oxidative phosphorylation through the enzymes Translocase and ATPase
(favoring the Warburg effect) and the cell cycle through E2F and CD44, inhibits
the prostate cancer stem cells and prevents metastasis (Liu et al. 2011 ).
In the numerous papers devoted to microRNAs and cancer, we can notice the
possibility of an under-expression of the microRNA hsa-miR-320 which reduces
the PFK activity (Tang et al. 2012 ), favoring the high glycolysis rate. Associated
like in the melanoma data with a blockage of the oxidative phosphorylation or with
an over-expression of hsa-miR-19a which inhibits the Pyruvate Dehydrogenase, we
have another example reinforcing the Warburg hypothesis concerning the energetic
origin of cancer. The last example of miR-dependent cancer is the Hepatocellular
Carcinoma (HCC), the major primary liver cancer. The glypican-3 (GPC3) is one of
the most abnormally expressed genes in this cancer, which could play a role in liver
carcinogenesis. In (Maurel et al. 2012 ; Huang et al. 2012 ) using a functional
screening, the authors found that miR-96, miR-129-1-3p, miR-219-5p miR-1271,
miR-1291, and miR-1303 differentially control the GPC3 expression in HCC cells.
More precisely, miR-219-5p exerts its tumor-suppressive effect in hepatic carcino-
genesis through its negative regulation of GPC3 expression.
Eventually, we can notice the role of the tumor suppressors like p53, p63, and
p73, which are highly controlled by and are controlling numerous micro-RNAs
[cf. Figs. 4.15 and 4.17 and Boominathan ( 2010a ) and Boominathan ( 2010b )]. The
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