There was a 20-30 disparity on positive NAC response in this study compared to other studies. Based on the type of positive respones in this study,
from the 18 samples with positive NAC response, 16 samples 25.80 had PR and 2 samples 3.23 had cCR and pCR. This results were relatively lower
compared to the results from Alvarado-Cabrero et al 2009. Eight percent of their samples had pCR, while Tewari et al 2010 found a higher pCR of 14.
There were large disparities between the results from this study compared to other studies. These differences were probably caused by the relatively higher
tumor size, younger samples, and other biological nature of LABC in this study which is unpredictable Viale, 2011. There is still no agreement about the impact
of tumor size to chemotherapy response. Tewari et al 2008 stated that the bigger the tumor size, the less favourable the chemotherapy response compared to
smaller sized tumors. While Manuaba 2006 found no significant relationship between tumor diameter or tumor volume with NAC response.
Some studies stated there was no significant relationship between age and biological nature or feature in LABC. Some found that younger LABC patients
tend to have more agressive tumor with ER negative status and higher tumor grade. Several biomarkers have been significantly associated with younger
patients BRCA-1 and BRCA-2, p53, HER2Neu, ERPR, LVI, Ki-67 and they have been associated with negative chemotherapy response DeMore, 2006;
Evans,
et al
., 2006.
5.3 mRNA Caspase-3 Level Decrease Correlation with Chemotherapy Response Risk
The apoptosis event plays a crucial role in life of simple organisms to complex organisms. Apoptosis is an active programmed cell death mechanism,
physiologic in nature and involves a number of physical and chemical protein molecules reactions. This mechanism occurs in phases and is well organized, such
mechanisms take place at the cell membrane, cytoplasm, nucleus, and will end with cell death. Programmed cell death or apoptosis is a very strict controlled
process which acts as cells mechanism to maintain homeostasis Vermeulen,
et al
., 2005. Table 3 showed that mRNA Caspase-3 level decrease post first cycle NAC
was a risk for negative chemotherapy response in LABC patients p=0,007. Therefore, the role of Caspase-3 as the executor of apoptosis process was crucial
in chemotherapy or other cytotoxic therapy. mRNA Caspase-3 is a gene which actively translates Caspase-3 enzyme after first cycle of chemotherapy and
represents a linear relationship with Caspase-3 level decrease, in other words, an increase in mRNA Caspase-3 has a linear potential with the increase of Caspase-3
enzyme expression. That event was observed in this study from the decrease of mRNA Caspase-3 level prechemotherapy and postchemotherapy t-paired Test
0,87±1,96 pgmL, nilai
p
0,05. Several studies had similar finding, Parton et al 2002 conducted an in
vivo multi centered study London, California, and Tokyo to determine the relationship between key components in breast cancer apoptosis mechanism
before and 24 hours after induction chemotherapy. They found a significant
correlation between apoptosis component Active Caspase-3 with proliferation component Expression of Inhibitor of Apoptosis ProteinXIAP, with marked
increase in apoptosis and decrease in proliferation 24 hours after induction chemotherapy. Parton et al 2002 concluded that chemotherapy induction will
induce apoptosis process through Bax activation and Caspase-3 which will degrade DFF-40 protein substrate and will lead to DNA fragmentation inside the
nucleus. Based on Parton et al 2002 findings, a similar event was observed in our study.
Caspase-3 as an executoreffector in apoptosis process held a key role in determining cell’s response or resistance to chemotherapy or other cytotoxic
agents. Devarajan et al 2002 studied this potential by observing down regulation of Caspase-3 using MCF-7 breast cancer cell line culture. They found that a
deficiency in Caspase-3 expression will affect apoptosis process after chemotherapy Doxorubicin and was an important factor in tumor cell growth.
Vegran et al 2006 found that there was a contradictory function ratio between Caspase-3 transcription with its expression one of which was in favor for
cyclophosphamide based NAC in LABC. Based from Devarajan et al 2002 and Vegran et al 2006, a similar result was observed in our study. We also found that
Caspase-3 as an executor in chemotherapy induced apoptosis process.
Yang et al 2007 conducted a study on MCF-7 and MDA-MB-231 cell culture to observe the role of Caspase-3 in cell death mechanism due to genistein
Soy Isoflavone exposure as a cytotoxic agent. They found that Caspase-3 activation was crucial in cell apoptosis in cultured cells with estrogen receptor
status. This study had a clinical relevance where Caspase-3 regulation in breast cancer had a similar downregulation event which was also observed in cultured
cells. Similar event was also observed in our study compared to Yang et al in 2007.
A multi centered clinical study by Nigam et al 2008 about Cenchroman CC as a antineoplastic agent candidate for stage IIIIV breast cancer found that
CC mediates apoptosis on cultured breast cancer cells MCF-7 and MDA-MB- 231 with positivenegative estrogen receptor status. They used a previous study
using tamoxifen on cultured breast cancer cells MCF-7 with positive estrogen receptor status as control. This study showed that CC induced apoptosis through
caspase pathway on cultured breast cancer cells line while not dependent of estrogen receptor status, which was the same for Tamoxifen. Unfortunately,
Nigam et al 2008 did not elaborate on which Caspase played a role in their study.
Cappellini et al 2009 studied the role of Caspase-3 on apoptosis of MCF 7 cultured breast cancer cells using Roscovitine as Cyclin Dependent Kinase
Inhibitor and Sangivamycine, a nucleoside analog, which can induce Caspase-3 dependent breast cancer cell apoptosis through P-glycoprotein cleavage. This
study proved that Caspase-3 played a specific role n P-glycoproten cleavage in vivo and also in effective therapy for P-glycoprotein expressing tumors. In
accordance to Cappellini et al 2009, our study also found that Caspase-3 as played an important role as executor for apoptosis. Vegran et al 2011 used
cultured breast cancer cells MCF-7 and HBL1000 to determine the role of
Caspase-3 isoforms as variant of alternative splicing pre-mRNA caspase which acts as antagonist for Caspase-3 apoptosis executor function by inhibiting
apoptosome. Caspase-3 isoforms overexpression wil inhibit chemotherapy induced apoptosis using Etoposide and MTX. We did not evaluate the role of
Caspase-3 isoforms in our study, therefore the possibility of Caspase-3 isoforms in reducing chemotherapy induced apoptosis needs to be studied further.
An experimental study by Petanidis et al 2013 showerd the effects of cadmium Cd as carcinogen in breast cancer cultured cells line MCF-7 on cell
transformation and mestastasis. Their study result showed that Cd had a significant stimulation effect to H-Ras gene expression which will lead to
increased activity of Caspase-3 on apoptosis using 100-1000 nM Cd dose.
The role of Bcl-2, caspases family, and p53 have been established in programmed cell death, even so the role of caspase-9, -3,-7 were still discussed in
many studies. Brentnall et al 2013 studied the roles of capases-9, -3, -7 in apoptosis intrinsic process. Their results showed that three of those caspases had
different roles, Caspase-9 played a role in mitochondrial morphology changes and will be activated after cytochrome-c release and Bid into tBid in ROS forming.
While Caspase-7 was known as an effector caspase which is not involved in cell death but played a role in apoptotic cells detachment. Caspase-3 specificallya had
a role as executor after being activated by caspase-9 and another function of caspase-3 was to inhibit ROS production. A similar finding was also found in our
study.
5.4 Apoptosis Index Level Decrease Correlation with Chemotherapy Respons
